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  • 1990-1994  (10,794)
  • 1965-1969
  • 1960-1964  (4,297)
  • 1905-1909
  • 1890-1899
  • 1993  (10,794)
  • 1962  (4,297)
  • Chemistry  (15,069)
  • Polymer and Materials Science  (5,654)
  • Biochemistry and Biotechnology  (846)
  • Insulin
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  • 1990-1994  (10,794)
  • 1965-1969
  • 1960-1964  (4,297)
  • 1905-1909
  • 1890-1899
Year
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  • 1
    Electronic Resource
    Electronic Resource
    Influence of fiber, xylitol and fructose in enteral formulas on glucose and lipid metabolism in normal subjects (1993)
    Springer
    Journal of molecular medicine 71 (1993), S. 290-293 
    Details
    ISSN: 1432-1440
    Keywords: Diabetes mellitus ; Enteral formula ; Fructose ; Insulin ; Xylitol
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary To verify the benofit of nonglucose carbohydrates and fiber in enteral formula diets we studied the postprandial metabolism of eight healthy subjects after the intake of two helpings (25 g carbohydrates each) of five commonly used enteral formulas over 4 h. There were no significant differences in postprandial concentrations of blood glucose among the formulas. The area under the curve of postprandial insulin values, however, was significantly smaller after consumption of the fructose-containing formula (1948±285 μU min ml−1, P〈0.05) than after fiber-free (3222 ±678 μU min ml−1) or two fiber-containing products (2664±326 μU min ml−1, P〈0.05; and 3040±708 μU min ml−1, P〈0.05). The insulin area of the xylitol-containing formula (2307±364 μU min ml−1) was significantly smaller compared to the fiber-free product (P〈0.05). In addition, we found the postprandial increase in triglycerides to be significantly higher after the xylitol-containing formula (from 0.93±0.14 to 1.25±0.22 mmol/1) than after the fiber-free product (from 0.82±0.13 to 0.97±0.16 mmol/1, P〈0.05) or the two fiber-containing products (from 0.88±0.16 to 0.96±0.18 mmol/1, P〈0.05; and from 0.80±0.08 to 0.95±0.10 mmol/l, P〈0.05). We conclude that a patient with type 11 diabetes may benefit from replacing glucose and glucose-equivalent carbohydrates with fructose or xylitol.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00184729
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  • 2
    Electronic Resource
    Electronic Resource
    Insulin enhances angiotensin II induced DNA synthesis in vascular smooth muscle cells of the rat (1993)
    Springer
    Journal of molecular medicine 71 (1993), S. 379-382 
    Details
    ISSN: 1432-1440
    Keywords: Angiotensin II ; Insulin ; Smooth muscle cell ; Vascular
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Hypertension has a high prevalence among subjects with decreased insulin sensitivity and/or hyperinsulinemia. Furthermore, angiotensin II plays a pivotal role in the regulation of vascular tone and is known to induce hypertrophy and/or hyperplasia in vascular smooth muscle cells. In the present study, the effect of insulin on angiotensin II induced smooth muscle cell growth (Wistar-Kyoto rat) was investigated. Cell growth was assessed by the measurement of [3H]thymidine incorporation into cell DNA. Insulin in a concentration range of 1.7 × 10−10–1.7 × 10−6 M lacked any effect on cell DNA synthesis. However, insulin enhanced the angiotensin 11 induced DNA synthesis in a concentration-dependent manner. This effect was similar in cells with a weak and in cells with a marked response in DNA synthesis to stimulation with 100 nM angiotensin 11. In conclusion, insulin is able to enhance angiotensin 11 induced DNA synthesis and may therefore function as a growth cofactor in vascular smooth muscle cells.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00186627
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  • 3
    Electronic Resource
    Electronic Resource
    Bromocriptine treatment over 12 years in acromegaly: effect on glucose tolerance and insulin secretion (1993)
    Springer
    Journal of molecular medicine 71 (1993), S. 372-378 
    Details
    ISSN: 1432-1440
    Keywords: Acromegaly ; Blood glucose ; Bromocriptine ; Glucose tolerance test ; Insulin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary It is not known whether the beneficial effect of bromocriptine on glucose homeostasis in acromegaly is limited by a certain duration of therapy. To elucidate this problem, oral glucose tolerance tests were performed in 12 acromegaly patients before bromocriptine medication, under therapy (15.0 ± 6.8 mg/day for 12 ± 3 years), and during a 2-week drug withdrawal after long-term treatment. Initially altered glucose tolerance was normalized in 4 of 5 patients under bromocriptine therapy. During drug withdrawal the mean fasting glucose level and the mean glucose concentration at 120 min after oral glucose load increased from 5.05 ± 0.61 to 5.77 ± 0.78 mmol/1 and from 5.61 ±2.05 to 7.55 ± 3.05 mmol/1, respectively. A deterioration in glucose homeostasis was observed in 9 patients, and impaired glucose tolerance was ameliorated (but not to normal range) in 2 when bromocriptine was withdrawn. The proportion of alterations in glucose tolerance during drug withdrawal corresponded to that before the beginning of long-term bromocriptine treatment. Impaired glucose tolerance, observed in 2 patients under bromocriptine treatment, seemed to be compensated because a distinct elevation of glycosylated hemoglobin A1c was not observed. Bromocriptine led to a significant decrease in basal as well as glucose-stimulated insulin levels, and growth hormone secretion during oral glucose load was reduced in all 12 patients. Similarly to the increased growth hormone secretion after drug withdrawal in 11 patients, a rise in glucose-stimulated insulin secretion was found in all patients; hereby, the mean insulin levels at 0 and 120 min during oral glucose load rose significantly from 7.5 ± 2.6 to 12.1 ± 5.1 mU/1 (P〈0.01) and from 71.3±52.1 to 101.4±50.7 mU/1 (P〈0.02), respectively. A direct relationship between disturbance in glucose homeostasis and degree of hypersomatotropism was not observed. Our data confirm that the beneficial effect of bromocriptine therapy on glucose homeostasis in selected patients with acromegaly is still present after dopaminergic treatment over a mean period of 12 years. Compared with the published rates on improved glucose homeostasis under octreotide, the effect of bromocriptine seems to be more favorable.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00186626
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  • 4
    Electronic Resource
    Electronic Resource
    Insulin enhances the growth of cartilage in organ and tissue cultures of mouse neonatal mandibular condyle (1993)
    Springer
    Calcified tissue international 52 (1993), S. 291-299 
    Details
    ISSN: 1432-0827
    Keywords: Insulin ; Cartilage ; Growth ; Condyle ; Mandible ; Mouse ; In vitro
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary Condylar cartilages were cultured in the form of organ cultures on top of collagen sponges in medium containing 2% fetal calf serum and were treated with 3.5–350 nM insulin for 6 days. Doses of 175 nM of insulin caused a marked increase (+96%) in DNA synthesis and in proteoglycan production (+74%), features that manifested themselves structurally by a 60% increase in overall size of the cultured explants. Using a tissue culture system comprised of cartilage progenitor cells, insulin was found to enhance the differentiation of the progenitor cells so that by 6 days in culture and appreciable nodule of differentiated chondrocytes developed. The latter was surrounded by perichondrial cells whereas the extracellular matrix within the newly formed, insulin-induced, nodule reacted positively for cartilagespecific antigens (type II collagen and bone sialoprotein). It is suggested that insulin induces a direct stimulatory effect on progenitor cell proliferation, cartilage differentiation, and extracellular matrix deposition.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00296654
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  • 5
    Electronic Resource
    Electronic Resource
    Serum insulin/glucose ratio and urinary loss of insulin after trauma in young animals: effect of adrenergic blockade (1993)
    Springer
    Pediatric surgery international 8 (1993), S. 210-214 
    Details
    ISSN: 1437-9813
    Keywords: Parenteral hyperalimentation ; Insulin ; Adrenergic alpha-receptor blockers ; adrenergic beta-receptor blockers
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Hyperglycemia and relative hypoinsulinemia are characteristic in the post-traumatic period. The altered insulin kinetics in this phase are dependent on many factors, which include stimulation of adrenoreceptors of pancreatic beta-cells and increased urinary clearance of insulin. Using the young rabbit as an experimental model, two series of experiments were designed. In study 1 (effect of trauma on serum insulin/glucose [I/G] ratio and urinary loss of insulin) two groups of animals (control and trauma) on parenteral nutrition were studied during 4 days. In study 2, in an acute 3-h period the effects of alpha- and beta-adrenoceptor blockers on insulin secretion were investigated. The animals were divided into four groups: control, trauma, trauma + phentolamine, and trauma + propranolol. In study 1 it was demonstrated that after trauma there was a decrease in I/G ratio and an increase in urinary loss of insulin, but no alteration in absolute levels of serum insulin. In study 2 we could demonstrate that treatment with adrenoceptor blockers did not prevent the lowering effect of trauma on I/G ratio. It is suggested that the diabetes-like state of the post-injury period is a complex phenomenon that is dependent on other important factors, as well as catecholamine inhibition of insulin secretion.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00182520
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  • 6
    Electronic Resource
    Electronic Resource
    Fetal antigen 1 (FA1) in the human pancreas: cell type expression, topological and quantitative variations during development (1993)
    Springer
    Anatomy and embryology 187 (1993), S. 335-341 
    Details
    ISSN: 1432-0568
    Keywords: Fetal antigen 1 ; Insulin ; Pancreas ; Development ; Exocrine ; Endocrine ; Immunohistochemistry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Monospecific rabbit anti-human fetal antigen 1 (FA1), was used to examine the distribution of FA1 during the development of the human fetal pancreas and liver using an indirect immunoperoxidase technique. FA1 was expressed by 94% of the glandular epithelial cells of the branching ducts in the pancreatic anlage at week 7 of gestation. This pattern changed during the development of the human pancreas, 64% of the glandular cells being FA1 positive at week 17 of gestation, decreasing to 11% in the infant (4 months after birth). In the infant and adults the FA1 expression was restricted to a subpopulation of β-cells within the islets of Langerhans. Insulin immunoreactive cells were scattered throughout the epithelium of primitive branching pancreatic ducts at week 7 of gestation, well before the formation of islets. From the 7th through to the 17th week of gestation, FA1 was found in the cytoplasm of fetal hepatocytes, whereas no staining was observed in the liver from a 4-month-old infant. No FA1 expression was found in the epithelium of the developing gut. The present findings indicate that the glandular epithelial cells in the developing pancreas may serve as stem cells, which, if appropriately induced, may differentiate into endocrine cells. Fetal antigen 1 (FA1) may take part in or be a result of this differentiation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00185891
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  • 7
    Electronic Resource
    Electronic Resource
    Insulin excess counteracts the effects of HDL on intracellular sterol accumulation in cultured human skin fibroblasts (1993)
    Springer
    Diabetologia 36 (1993), S. 942-947 
    Details
    ISSN: 1432-0428
    Keywords: Insulin ; HDL ; cholesterol ; atherosclerosis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Both Type 1 (insulin-dependent) and Type 2 (non-insulin-dependent) diabetic individuals are at increased risk of developing ischaemic heart disease. Insulin excess, present in both diabetic groups, may play an important pathophysiologic role in accelerating the atherogenic process. In this study, cultured human skin fibroblasts were incubated with varying concentrations of insulin to test the role of insulin on cell cholesterol homeostasis and on HDL3-mediated removal of excess cholesterol from cells. Insulin excess (1-2-100 nmol/l) resulted in a significant dose-dependent reduction in HDL3-mediated cholesterol efflux from the intracellular unesterified cholesterol pool of cultured human skin fibroblasts. Similar insulin concentrations resulted in impaired HDL-mediated cholesterol efflux from the cell membrane but had no effect on non-HDL-mediated efflux. The effect of insulin on cholesterol esterification and biosynthesis was assessed by14C-oleate labelling. The addition of HDL3 (50 μg) resulted in a significant decrease in14C-labelled cholesterol ester, reflecting a decrease in intracellular unesterified cholesterol, which was partially reversed by the addition of insulin. Insulin had no effect on the incorporation of14C-oleate into unesterified cholesterol. During simultaneous incubation of fibroblasts with LDL and HDL, insulin resulted in an increase in cholesterol esterification and inhibited ability of HDL to promote the decrease in esterification. Thus, we have shown that insulin exess counteracts the beneficial effects of HDL that involve removal of cellular cholesterol and may in part promote atherogenesis by this mechanism
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02374477
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  • 8
    Electronic Resource
    Electronic Resource
    Cellular ionic effects of insulin in normal human erythrocytes: a nuclear magnetic resonance study (1993)
    Springer
    Diabetologia 36 (1993), S. 146-149 
    Details
    ISSN: 1432-0428
    Keywords: Insulin ; calcium ; magnesium ; pH ; nuclear magnetic resonance spectroscopy ; erythrocytes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Elevated erythrocyte cytosolic free calcium, and suppressed free magnesium and pH values are associated with the hyperinsulinaemia and insulin resistance of hypertension, obesity, and Type 2 (non-insulin-dependent) diabetes mellitus. To determine the role of insulin in this process, we utilized 19F- and 31P-nuclear magnetic resonance spectroscopy to study the cellular ionic effects of insulin in vitro on normal human erythrocytes. Insulin elevated cytosolic free calcium levels in a dose- and time-dependent manner. The effect began at 10 μU/ml, peaked at 200 μU/ml, and continued at both the 500 μU/ml and 1000 μU/ml doses. At 200 μU/ml, free calcium levels rose from 24.6±2.5 nmol/l to a peak value at 120 min of 66.4±11 nmol/l (p〈0.05 vs basal), levels remaining elevated throughout the incubation (45.7±5.6 nmol/l at 60 min, and 47.9±9.1 nmol/l at 180 min, p〈0.05 vs basal, respectively). Similarly, insulin also increased intracellular free magnesium at all time points (basal: 177± 11 μmol/l; 60 min: 209±19 μmol/l; 120 min: 206±22 μmol/l; and 180 min: 202±12 μmol/l; p〈0.05 vs basal at all times). No insulin-induced changes in pH were observed. We conclude (i) that insulin in physiological concentrations may participate in regulating divalent cations in the mature human erythrocyte, (ii) that insulin per se cannot account for the previously described cellular ionic lesions of hypertension and diabetes, and (iii) that future clinical studies of cell ion metabolism should be conducted in the fasting state, be controlled for ambient circulating insulin levels, or both.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00400696
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  • 9
    Electronic Resource
    Electronic Resource
    Demonstration of a novel apamin-insensitive calcium-activated K+ channel in mouse pancreatic B cells (1993)
    Springer
    Pflügers Archiv 422 (1993), S. 443-448 
    Details
    ISSN: 1432-2013
    Keywords: K+-channel ; Ca2+ ; Apamin ; Pancreas ; Insulin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The whole-cell configuration of the patchclamp technique was used to characterize the biophysical and pharmacological properties of an oscillating K+-current that can be induced by intracellular application of GTP[γS] in mouse pancreatic B cells (Ämmälä et al. 1991). These K+ conductance changes are evoked by periodic increases in the cytoplasmic Ca2+ concentration ([Ca2+]i) and transiently repolarize the B cell, thus inhibiting action-potential firing and giving rise to a bursting pattern. GTP[γS]-evoked oscillations in K+ conductance were reversibly suppressed by a high (300 μM) concentration of carbamylcholine. By contrast, α2-adrenoreceptor stimulation by 20 μM clonidine did not interfere with the oscillatory behaviour but evoked a small sustained outward current. At 0 mV membrane potential, the oscillating K+-current elicited by GTP[γS] was highly sensitive to extracellular tetraethylammonium (TEA; 70% block by 1 mM). The TEA-resistant component, which carried approximately 80% of the current at −40 mV, was affected neither by apamin (1 μM) nor by tolbutamide (500 μM). The current evoked by internal GTP[γS] was highly selective for K+, as demonstrated by a 51-mV change in the reversal potential for a sevenfold change in [K+]o. Stationary fluctuation analysis indicated a unitary conductance of 0.5 pS when measured with symmetric (≈ 140mM) KCl solutions. The estimated singlechannel conductance with physiological ionic gradients is 0.1 pS. The results indicate the existence of a novel Ca2+-gated K+ conductance in pancreatic B cells. Activation of this K+ current may contribute to the generation of the oscillatory electrical activity characterizing the B cell at intermediate glucose concentrations.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00375069
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  • 10
    Electronic Resource
    Electronic Resource
    Arachidonate activation of protein kinase C may be involved in the stimulation of protein synthesis by insulin in L6 myoblasts (1993)
    Springer
    Bioscience reports 13 (1993), S. 359-366 
    Details
    ISSN: 1573-4935
    Keywords: Insulin ; L6 myoblast ; protein synthesis ; protein kinase C ; arachidonate ; DAG
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Insulin stimulated protein synthesis in L6 myoblasts but did not increase the labelling of DAG or the release of phosphocholine from phosphatidylcholine. The DAG lipase inhibitor, RHC 80267, more than doubled the amount of label appearing in DAG but did not stimulate protein synthesis. Even in the presence of the DAG lipase inhibitor insulin failed to have any effect on DAG labelling, and conversely RHC 80267 did not modify the insulin-induced increase in protein synthesis. These results suggest that endogenous DAG production is not involved in the stimulation of protein synthesis by insulin. However, exogenous diacylglycerols (1-oleoyl-2-acetyl glycerol and 1-stearoyl-2-arachidonoyl glycerol) both stimulated protein synthesis in L6 myoblasts. The efficacy of the former (arachidonatefree) DAG suggested that their action was by activation of protein kinase C rather than by arachidonate release and prostaglandin formation. Ibuprofen, an inhibitor of cyclo-oxygenase failed to block the effects of insulin whereas a second cyclo-oxygenase inhibitor, indomethacin had only a partial inhibitory effect. The protein kinase C (PKC) inhibitor, RO-31-8220, totally blocked the effect of insulin. Since indomethacin is also recognised to inhibit phospholipase A2, the data suggests that insulin acts on protein synthesis in myoblasts by arachidonate activation of PKC.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01150480
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  • 11
    Electronic Resource
    Electronic Resource
    Fluorescence anisotropy and light-scattering studies of the interaction of insulin with liposomes (1993)
    Springer
    Journal of fluorescence 3 (1993), S. 215-217 
    Details
    ISSN: 1573-4994
    Keywords: Insulin ; lecithin liposomes ; light scattering ; fluorescence anisotropy ; 1,6-diphenyl-1,3,5-hexatriene
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The interaction between zinc-stabilized insulin and lecithin liposomal membranes was studied using DPH fluorescence anisotropy and light-scattering techniques. To ascertain a possible influence of a charge on the insulin molecule, experiments were performed at pH 4.5 (insulin possesses a positive charge) and at pH 7.4 (the charge of insulin is negative). Measurements at pH 4.5 revealed significant changes in scattered light intensity induced by the addition of insulin to lecithin liposomes. With increasing time of storage of liposomes the insulin effect became faster and more pronounced. At pH 7.4, significant changes in scattered light were registered only in the case of liposomes stored for 5 days. In these liposomes a peroxidation process of lecithin was revealed. No significant changes induced by insulin were observed in DPH fluorescence anisotropy either at pH 4.5 or at pH 7.4, which suggested the absence of an interaction of insulin with the hycrophobic core of liposomes. Thus, the observed changes in scattered light could be interpreted in terms of the insulin association to the liposomal surface in the case of phospholipid peroxidation and/or acidic pH.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00865264
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  • 12
    Electronic Resource
    Electronic Resource
    Metabolic regulation of glucose transport (1993)
    Springer
    The journal of membrane biology 135 (1993), S. 1-10 
    Details
    ISSN: 1432-1424
    Keywords: Glucose transporter ; GLUT ; GLUT isoforms ; Oxidative phosphorylation ; Insulin ; Transporter activation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00234646
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  • 13
    Electronic Resource
    Electronic Resource
    Quantitation of Na+/K+-ATpase and glucose transporter isoforms in rat adipocyte plasma membrane by immunogold labeling (1993)
    Springer
    The journal of membrane biology 136 (1993), S. 63-73 
    Details
    ISSN: 1432-1424
    Keywords: Insulin ; Immuno-electron microscopy ; Caveolae ; Na+/K+-ATPase ; Glucose transporters
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract We have quantitated and studied the topology of isoforms of the Na+/K+-ATPase and of the glucose transporter in rat adipocyte plasma membranes. Adipocytes were incubated with or without insulin for 15 min. Sheets of native plasma membrane, with the cytoplasmic face exposed, were prepared by adsorption to EM grids. Grids were incubated in parallel with monoclonal antibodies against the Na+/ K+-ATPase isoforms α1 and α2, and the glucose transporter isoforms GLUT1 and GLUT4, followed by immunogold labeling, negative staining and quantitation by counting of the gold particles in electron micrographs. In addition, the distribution of glucose transporters and Na+/K+-ATPase isoforms in subcellular membrane fractions prepared by an established fractionation procedure was monitored by Western blotting. We found that the Na+/K+-ATPases and the glucose transporters were confined to the planar part of the plasma membrane, without association to caveolar invaginations. The vast majority of the Na+/K+-ATPase molecules in the adipocyte plasma membrane were of the α2 isoform; GLUT4 was the dominating glucose transporter isoform. The total number of Na+/K+-ATPase molecules labeled in the plasma membrane was 3.5×105 per cell, independent of insulin stimulation. Concomitantly, insulin increased GLUT4 labeling sevenfold to a value of 3.5×105 per cell.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00241490
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  • 14
    Electronic Resource
    Electronic Resource
    Comparison of in situ hybridization and immunocytochemistry for the detection of residual beta cells in the pancreas of streptozotocin-treated diabetic rats (1993)
    Springer
    Acta diabetologica 30 (1993), S. 118-122 
    Details
    ISSN: 1432-5233
    Keywords: Diabetes mellitus ; Immunocytochemistry ; In situ hybridization ; Insulin ; Streptozotocin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The relative efficacy of immunocytochemistry versus in situ hybridization in identifying residual beta cells was studied in rats with streptozotocin-induced diabetes. Consecutive sections of pancreas of streptozotocin-treated diabetic rats and control animals were alternately subjected to in situ hybridization (synthetic oligonucleotides complementary to rat preproinsulin mRNA) and immunocytochemistry (monoclonal antibodies to insulin). The results obtained with both methods were quantitated with the use of computer-assisted image analysis, and the ratio of cells positive by immunocytochemistry to those positive by in situ hybridization was determined. Under normoglycaemic conditions the values obtained by immunocytochemistry correlated well with those obtained by in situ hybridization (immuno/in situ 〉 95%). In the streptozotocin diabetic animals, however, immunocytochemistry resulted in a distinct underestimation of the number of residual beta cells (immuno/in situ 〈 80%). This difference was even more striking in small islet cell clusters (〈100 μm) immuno/in situ 20%). These results suggest that in situ hybridization for prohormone mRNA is the method of choice for the identification of residual or regenerating beta cells with very low insulin content. Caution should be used when interpreting quantitative data in diabetic conditions that are based exclusively on immunocytochemical detection methods.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00572853
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  • 15
    Electronic Resource
    Electronic Resource
    Proportional proinsulin responses in first-degree relatives of patients with type 2 diabetes mellitus (1993)
    Springer
    Acta diabetologica 30 (1993), S. 132-137 
    Details
    ISSN: 1432-5233
    Keywords: C-peptide ; Diabetes mellitus ; Glucose clamp ; Insulin ; Proinsulin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Elevated fasting proinsulin immunoreactive material (PIM) has previously been found in patients with type 2 (non-insulin-dependent) diabetes mellitus. It is not known whether this is a genetic trait or whether it is related to the manifestation of type 2 diabetes. Neither is it clear whether the raised fasting insulin immunoreactivity previously observed in first-degree relatives of patients with type 2 diabetes is due to raised PIM. Furthermore, it has not been investigated whether first-degree relatives have altered PIM responses to different secretagogoues. To study this, PIM, insulin and C-peptide were measured in patients with type 2 diabetes, in their first-degree relatives and in healthy control subjects in the fasting state and in relatives and controls during a hyperglycemic clamp. At the end of the hyperglycemic clamp, 0.5 mg of glucagon was given intravenously to stress the beta cells further. Fasting PIM concentrations were significantly higher in patients with type 2 diabetes (P〈0.05). These patients did not have significantly elevated fasting insulin levels when corrected for PIM. In the relatives, fasting insulin concentrations were elevated but PIM levels were normal suggesting that the increase in fasting insulin concentrations reflected an increase in true insulin. The incremental PIM, insulin and C-peptide responses to glucose and glucagon in the relatives were not different from those in the controls. We conclude that elevated fasting PIM levels in patients with type 2 diabetes seem not to be a genetic trait. First-degree relatives of patients with type 2 diabetes are truly hyperinsulinemic in the fasting state, and they have proportional PIM, insulin and C-peptide responses to glucose and glucagon.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00572856
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  • 16
    Electronic Resource
    Electronic Resource
    The endogenous cyclic AMP antagonist, cyclic PIP: its ubiquity, hormone-stimulated synthesis and identification as prostaglandylinositol cyclic phosphate (1993)
    Springer
    Acta diabetologica 30 (1993), S. 220-232 
    Details
    ISSN: 1432-5233
    Keywords: Cyclic AMP antagonist ; Inositol phosphates ; Insulin ; Noradrenaline ; Prostaglandin E
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract This report shows that the cyclic AMP antagonist cyclic PIP is present in all organs and tissues of the rat so far examined: brain, heart, lung, intestine, kidney, liver, spleen, skeletal muscle and fat. The synthesis of cyclic PIP is stimulated by insulin or noradrenaline (α-adrenergic action) in a dose-dependent fashion. Increasing cyclic PIP synthesis with increasing insulin concentrations matches the insulin receptor binding curves. Cyclic PIP levels in blood serum remain low after hormonal stimulation and no cyclic PIP can be detected in urine. As an indication of its ubiquity, cyclic PIP was even detected in yeast. Prostaglandin E (as shown by incorporation of [3H]PGE into cyclic PIP and demonstration of a constant specific activity), myo-inositol (as shown by acid hydrolysis of the dephosphorylated cyclic PIP and mass spectrometric identification of the products) and one phosphate (as shown by the ionic nature of cyclic PIP and its inactivation by phosphodiesterase plus phosphatase) are components of cyclic PIP. Chemical derivatization experiments of cyclic PIP suggest the phosphate to be bound to myo-inositol and the myo-inositol phosphate to the prostaglandin E by its C15-hydroxyl group.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00569933
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  • 17
    Electronic Resource
    Electronic Resource
    Comparative experimental study of autologous adipose tissue processed by different technqiues (1993)
    Springer
    Aesthetic plastic surgery 17 (1993), S. 113-115 
    Details
    ISSN: 1432-5241
    Keywords: Autologous adipose tissue ; Techniques ; Insulin ; Centrifugation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Different techniques for processing adipose tissue were tested in 40 Swiss Albino female mice. Our study established that the use of insulin did not show any positive effect on survival of adipocytes during their transplantation. Likewise, the use of a centrifuge machine, at high or low speed, for separating the adipose tissue components, completely destroyed the adipose cells and did not allow their survival.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02274731
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  • 18
    Electronic Resource
    Electronic Resource
    Islet amyloid polypeptide gene expression in the endocrine pancreas of the rat: a combined in situ hybridization and immunocytochemical study (1993)
    Springer
    Cell & tissue research 274 (1993), S. 467-474 
    Details
    ISSN: 1432-0878
    Keywords: IAPP (islet amyloid polypeptide) ; Endocrine pancreas ; In situ hybridization ; Immunocytochemistry ; Somatostatin ; Insulin ; Rat (Sprague Dawley)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The expression of the islet amyloid polypeptide (IAPP) gene within the endocrine pancreas and its correlation with insular neuroendocrine peptide localization were investigated in the rat. In situ hybridization with a 35S-labelled IAPP-mRNA specific oligonucleotide probe was combined with immunocytochemistry. In situ hybridization alone showed strong autoradiographic labelling of the pancreatic islets. In situ hybridization combined with immunocytochemistry for IAPP, revealed labelling of the IAPP-immunoreactive cells. However, when in situ hybridization was combined with immunocytochemistry for proinsulin, we noted a lack of proinsulin immunoreactivity in some peripherally located autoradiographically labelled islet cells. Furthermore, combination of in situ hybridization and immunocytochemistry for somatostatin showed autoradiographic labelling of somatostatin cells to a varying degree. This was further confirmed by showing cellular co-localization of IAPP and somatostatin by immunocytochemical double staining. We conclude that IAPP is mainly synthesized in insulin cells. Additionally, a subpopulation of the somatostatin cells is capable of IAPP synthesis. This may account for the relatively small reduction in the content of IAPP-mRNA in islets compared to the marked reduction of insulin mRNA after streptozotocin-induced diabetes in rats as previously reported.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00314543
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  • 19
    Electronic Resource
    Electronic Resource
    Immunohistochemical localization of insulin-like growth factor 1 and 2 in the endocrine pancreas of rat, dog, and man, and their coexistence with classical islet hormones (1993)
    Springer
    Cell & tissue research 273 (1993), S. 249-259 
    Details
    ISSN: 1432-0878
    Keywords: Endocrine pancreas ; IGF-1 ; IGF-2 ; Insulin ; Glucagon ; Somatostatin ; Pancreatic polypeptide ; Man ; Dog ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Immunohistochemical techniques were used to study the occurrence and distribution of insulin-like growth factor 1 (IGF-1) and IGF-2 in the pancreas of man, dog, and rat and their possible coexistence with insulin (INS), glucagon (GLUC), somatostatin (SOM) and pancreatic polypeptide (PP). All control experiments, including pre-absorption of the antisera with synthetic peptide hormones, indicated the specificity of the immunoreactions obtained. In all species investigated, IGF-2-immunoreactivity occurred exclusively in INS-immunoreactive cells as was found by the use of consecutive sections and double immunofluorescence on identical sections. In contrast, IGF-1-immunoreactivity co-existed with GLUC-immunoreactivity. In man, singular SOM-immunoreactive cells also contained IGF-1-immunoreactivity. Thus, IGF-1 and IGF-2 can be localized by means of immunohistochemistry in the mammalian pancreas, and can be shown to occur in different islet cell populations. It is presumed that IGF-1 derived from A-cells and/or D-cells acts on the B-cells in a paracrine manner. The co-existence of IGF-2-immunoreactivity and INS-immunoreactivity in the human, rat, and dog endocrine pancreas indicates that mammalian IGF-2 and INS genes are regulated simultaneously.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00312826
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  • 20
    Electronic Resource
    Electronic Resource
    Factors affecting myocardial 2-[F-18]fluoro-2-deoxy-d-glucose uptake in positron emission tomography studies of normal humans (1993)
    Springer
    European journal of nuclear medicine 20 (1993), S. 308-318 
    Details
    ISSN: 1619-7089
    Keywords: Positron emission tomography ; Myocardial glucose utilization rates ; Glucose ; Insulin ; Free fatty acids ; Glucagon
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The goal of this study was to identify the anatomic and physiologic factors affecting left ventricular myocardial 2-[F-18]fluoro-2-deoxy-d-glucose (FDG) uptake and myocardial glucose utilization rates (MRGlc) in normal humans. Eighteen healthy male volunteers were studied in the fasting state (4–19 h) and 16 after oral glucose loading (100 g dextrose) with positron emission tomography (PET) and FDG. Substrate and hormone concentrations were measured in each study. The kinetics of myocardial FDG uptake were evaluated using both a three-compartment model and Patlak graphical analysis. Systolic blood pressures and rate pressure products were similar in the fasting and postglucose states. MRGlc averaged 0.24±0.17 μmol/min/g in fasting subjects and rose to 0.69±0.11 μmol/min/g after glucose loading. Phosphorylation rate constant, k3, and MRGlc were linearly related (P 〈 0.001). Increases in MRGIc following glucose loading were correlated with plasma glucose, insulin and free fatty acid concentrations, ratios of insulin to glucagon levels, and influx rate constants of FDG. Glucose loading improved the diagnostic image quality due to more rapid clearance of tracer from blood and higher myocardial FDG uptake. When MRGlc, glucose and insulin concentrations, and insulin to glucagon ratios exceeded 0.2 μmol/min/g, 100 mg/dl, 19 μU/ml, and 0.2 μU/pg, respectively, myocardial uptake of FDG was always adequate for diagnostic use. FDG image quality and MRGlc were similar after relatively short (6 ±2 h) and overnight (16 ± 2 h) fasting. Significant (P〈0.05) regional heterogeneity of myocardial FDG uptake and MRGlc was observed in both the fasting and the postglucose studies. MRGlc and FDG uptake values in the posterolateral wall were higher than those in the anterior wall and septum. Thus, both 6-h and overnight fasts resulted in similarly low myocardial glucose utilization rates. While MRGlc and myocardial FDG uptake depended on plasma glucose, free fatty acid, and insulin concentrations, the results also suggest an additional dependency on plasma glucagon levels. Regional heterogeneities in myocardial FDG uptake and MRGlc are evident and independent of the subjects' dietary state. These regional heterogeneities need to be considered in studies of patients with cardiac disease.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00169806
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  • 21
    Electronic Resource
    Electronic Resource
    Serum LP(A) levels in randomized healthy men from different European countries (1993)
    Springer
    European journal of epidemiology 9 (1993), S. 497-503 
    Details
    ISSN: 1573-7284
    Keywords: Lipoprotein(a) ; Risk factors ; Blood lipids ; Insulin ; Anthropometry ; Europe
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Serum lipoprotein(a) [Lp(a) ], blood lipids, serum insulin and anthropometric parameters were determined in randomized samples of 38-year-old men living in six European cities: Ede (The Netherlands), Deinze (Belgium), Warsaw (Poland), Lumiar (Portugal), Verona and Naples (respectively in northern and in southern Italy). In total, 406 healthy men were studied. Serum Lp(a), blood lipids and serum insulin were measured in one laboratory. All the anthropometric and metabolic variables considered were statistically different among the participating sites, with the exception of Lp(a) serum levels. In spite of the lack of overall significant inter-center differences (Kruskal-Wallis test), the subjects from the two Italian cities had significantly lower Lp(a) serum levels than the subjects from Belgium and Portugal (Mann-Whitney U test, p 〈 0.01). In all cities the distribution of serum Lp(a) levels were highly skewed; the percentage of subjects with serum Lp(a) levels higher than 30 mg/dl (i.e., the commonly accepted risk level of cardiovascular disease) was 6% in both Verona and Naples (Italy), 12% in The Netherlands, 16% in Poland, 18% in Belgium and 19% in Portugal (for the last two cities, respectively, p 〈 0.02 and p 〈 0.01 vs Italian cities, chi-square test). Neither anthropometric (body mass index, waist/hip circumference ratio) nor metabolic (serum lipids and insulin) parameters showed any significant relationship with serum Lp(a) levels in any of the sites (Spearman's rank correlation). These data support the possibility of a difference in serum Lp(a) levels among different European countries.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00209527
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  • 22
    Electronic Resource
    Electronic Resource
    Frequency dependence of the complex dielectric constant of sodium carboxymethyl cellulose (1993)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 204 (1993), S. 51-61 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Dielektrizitätskonstante (ε′) nd dielektrischer Verlust (ε″) von drei Carboxymethylcellulose-Proben mit verschiedenem Substitutions- und Polymerisationsgrad wurden im Frequenzbereich 0,1 - 10000kHz bei Temperaturen zwischen 10 und 60oC gemessen. Im Gegensatz zu nativer Baumwollecellulose, die zwei Relaxztionsprozesse (β und γ) zeigt, wurde nur jeweils ein Relaxationsprozeß zwischen 0,1 und 1kHz gefundern. Die dielektrischen Eigenschaften hängen dabei nicht nur vo Substritutionsgrad, sondern auch vom gewichtsmittleren Polymerisationsgrad und der Homogenität der Substitution ab.
    Notes: The dielectric constant, ε′, and dielectric loss, ε″, were determined for three solid carboxymethyl cellulose samples having different levels of substitution and different degrees of polymerization over a frequency range of 0.1 - 10 000 kHz at temperatures from 10-60°C. In contrast to the two relaxation processes, γ and β, previously observed in native cotton cellulose, only one relaxation process within a frequency range of 0.1 - 1 kHz was identified. It was found that the dielectric properties do not only depend on the degree of substitution, but also on the weight-average degree of polymerization and uniformity of distribution.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1993.052040104
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  • 23
    Electronic Resource
    Electronic Resource
    An automated high pressure capillary rheometer with hydraulic driveDedicated to Prof. Dr. Otto Vogl on the occasion of his 65th birthday (1993)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 204 (1993), S. 63-71 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Es wird ein neues Kapillar-Rheometer beschrieben, bei dem der Druck, mit dem die Meßflüssigkeit durch die Kapillaren gepreßt wird, durch eine hydraulische Vorrichtung erzeugt wird. Das Gerät ist voll zautomatisiert und wird durch einen PC gesteuert. Verschiedene Meß-Moden können vorgewählt und dann automatisch ausgeführt werden. Einige vorläufige Ergebnisse an Newtonschen Flüssigkeiten und an Polymerlösungen zeigen das Funktionieren des neuen Rheometers.
    Notes: A new capillary rheometer design is described, in which a hydraulic device is used to produce the pressure driving the sample fluid through capillaries. The device is fully automated and controlled by a PC unit. Various measuring modes can be preselected and are automatically executed. Some preliminary results with New tonian fluids and with polymer solutions show the functioning of the new rheometer.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1993.052040105
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  • 24
    Electronic Resource
    Electronic Resource
    A redox reaction mediated by polymeric membranes containing electron carriers (1993)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 204 (1993), S. 73-83 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Naphthochinonderivate wurden als Elektronen- und Protonenüberträger in Polymermembranen für Redoxreaktionen eingesetzt. Eine solche, Vitamin K1 enthaltende Membran, läßt den Oxidations-Reduktions-Prozeß zwischen zwei wäßrigen Lösungen von Eisen(III) cyanid bzw. Natriumdithionit nur ziemlich langsam ablaufen. Ein effektiverer Überträger war Vitamin K3; die Reaktion verlief zunächst rasch, jedoch beiweideerholten Anwendungen immer langsamer, da ein Teil dieses, in senier reduzierten Form wasserlöslichen Überträgers während der Reaktion aus der Membran herausgelöst wurde. 2-Alkyloxy-1,4-naphthochinone wie z.B. das Hexyloxyderivat erwiesen sich als wirksame, die Reaktion unterstützende Elektronen- und Protonenüberträger, und in diesen Fällen führten wiederholte Anwendungen nicht zu Verzögerungen.
    Notes: A redox reaction was mediated by polymeric membranes which contain naphthoquinone derivatives as electron and proton carriers. When such a membrane containing vitamin K1 was placed between two aqueous solutions of potassium ferricyanide and sodium dithionite, the oxidation-reduction of them took place, but the reaction was rather slow. Although vitamin K3 was a more effective carrier and the reaction proceeded fast, the reaction rate decreased in the repeated runs. Since the reduced form of this carrier is slightly soluble in water, a part of the carrier got dissolved in the aqueous phase from the membrane during the reaction. 2-Alkyloxy-1,4-naphthoquinones such as 2-hexyloxy-1,4-naphthoquinone effectively transported electrons and protons through the polymeric membranes, promoting the membrane-mediated reaction; in these cases no retardation was observed in the repeated runs.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1993.052040106
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  • 25
    Electronic Resource
    Electronic Resource
    Zinkacrylat und andere feste Monomere als Vernetzungsmittel für ungesättigte PolyesterNach einem Beitrag zur Tagung der Arbeitsgemeinschaft „Verstärkte Kunststoffe“, Berlin, September 1991. (1993)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 204 (1993), S. 85-89 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: The peroxide-initiated copolymerisation of an unsaturated polyester with zinc acrylate, diallyl phthalate prepolymer and a solid vinyl ester resin was investigated. The curing was followed by means of gelation curves and differential scanning calorimetry. The studies showed that zinc acrylate has the highest reactivity.
    Notes: Die Peroxid-initiierte Copolymerisation eines ungesättigten Polyesters mnit Zinkacrylat, Diallylphthalat-Prepolymer und einem Vinylesterharz wurde untersucht. Der Härtungsverlauf wurde anhand der Gelierungskurven und mitels Differentialkalorimetrie verfolgt. Die Prüfungen zeigten, daß Zinkacrylat die größte Reaktivität hat.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1993.052040107
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  • 26
    Electronic Resource
    Electronic Resource
    Copolymers of anionic polymerization of octanelactam with laurolactam. II. Kinetics of isothermal crystallizationPart I cf.1. (1993)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 204 (1993), S. 91-100 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Die Kinetik der isothermen Kristallisation des anionisch hergestellten Copolyamids PA 8/12 aus ω-Octanlactam (OL) und ω-Laurinlactam (12-Dodecanlactam) (LL) wurde nach der Avrami-Gleichung über den gesamten Zusammensetzungsbereich mittels DSC untersucht. Die Kristallisationsparameter Halbwertszeit (t1/2), Avrami-Index (n), Geschwindigkeitskonstante (k) und Kristallinitätsgrad wurden für verschiedene Kristallisationstemperaturen bestimmt. Eine Beziehung dieser Parameter zur Copolyamidzusammensetzung sowie zu Kristallisations- und Unterkühlungstemperaturen wurde untersucht und die Ergebnisse diskutiert. Desweiteren wurden die Werte de hier behandelten mit denen der in der Literaturgeschriebenen Homopolymeren verglichen.
    Notes: The isothermal crystallization kinetics of the anionic copolyamides of ω-octanelactam (OL) with ω-laurolactam (LL) (nylon-8/nylon-12), covering a wide composition range (0/100 - 100/0 OL/LL, mol/mol), was established according to the Avrami equation by the use of differential scanning calorimetry. The crystallization parameters half-time crystallization (t1/2), Avrami index (n), rate constant (k), and reduced crystallinity were determined for various crystallization temperatures. These parameter values are correlated to the composition of the copolyamides, the crystallization and supercooling temperature, and the results are discussed.Differences in kinetic parameter values between the homopolymers of this paper and those for the hydrolytic nylon-8 and nylon-12 reported in literature were observed and discussed.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1993.052040108
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  • 27
    Electronic Resource
    Electronic Resource
    Possibilities for the formation and characterization of solid-state-structures in aromatic polyoxadiazoles (1993)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 204 (1993), S. 111-118 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Abhängig von den Fällbedingungen tritt Poly(p-phenylen-1,3,4-oxadiazole) in zwei Modifikationen auf. Dies kann sowohl durch FTIR-Spektroskopie als auch mit Röntgenweitwinkelstreuung nachgewiesen werden. In beiden Fällen zeigt jede Modifikation charakteristische Peaks. Bei der Verarbeitung zu Fäden oder Filmen aus Lösungen in konzentrierter Schwefeläure durch Fällen in Wasser wird die im thermodynamischen Ungleichgweicht stehende β-Modifikation erhalten. Unter speziellen Bedingungen ist es möglich, die dreidimensional geordnete Gleichgewichtsstruktur direkt herzustellen. Verarbeitungsprodukte aus dieser α-Modifikation weisen merklich höhere Festigkeiten auf.
    Notes: Depending on the coagulation conditions, poly(p-phenylene-1,3,4-oxadiazole) in the solid state forms two modifications, as can be evidenced by FTIR spectroscopy and by wide-angle X-ray scattering curves (WAXS). In both cases each modification is detectable by characteristic peaks. Processing of fibers or films from solutions in concentrated sulfuric acid by coagulation in water results in the formation of a thermodynamically non-equilibrium form, defined as β-modification. Under special conditions it is possible to obtain the three-dimensionally ordered equilibrium α-structure that leads to processing products with markedly higher tenacities.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1993.052040110
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  • 28
    Electronic Resource
    Electronic Resource
    Zur Optimierung der Synthese von Poly(p-phenylen-1,3,4-oxadiazol) in Oleum (1993)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 204 (1993), S. 101-110 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: By a new technique for the addition of monomers it is possible to increase the reproducibility of the synthesis of poly(1,4-phenylene-1,3,4-oxadiazoles) by one order of magnitude in relation to the known method, measured by the standard deviation of the relative viscosity of polymer solutions in concentrated sulfuric acid. This method leads to polymers with very high molecular weights under markedly milder reaction conditions and in shorter reaction times than by the classic method.The influence of the most important reaction parameters on the reaction rate and equilibrium of the polycondensation was investigated. An [η]/Mw-relation was established based on light-scattering and viscometric investigations of polymer solutions in concentrated sulfuric acid.
    Notes: Die Reproduzierbarkeit der Synthese von Poly(p-phenylen-1,3,4-oxadiazolen) in Oleum Kann durch eine veränderte Monomerzugabetechnik, gemessen an der Standardabweichung der relativen Lösungsviskosität, um eine Größenordunung verbessert werden. Die Polykondensation verläft unter deutlich milderen Bedingungen in kürzeren Reaktionszeiten zu Polymeren mit höheren Molmassen als nach der bekannten Methode.Der Einfluß verschiedener Parameter auf die Reaktionsgeschwindigkeit und das Polykondensationsgleichgewicht wurde eingehend untersucht. Auf der Basis streulicht photometrischer und viskosimetrischer Messungen an Polymerlösungen in konzentrierter Schwefelsäure wurde eine [η]/Mw-Bezeihung ermittelt.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1993.052040109
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  • 29
    Electronic Resource
    Electronic Resource
    Ölfettsäremodifizierte wäßrige Polymethacrylatdispersionen (1993)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 204 (1993), S. 127-137 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Water-borne paints have received greater attention. Existing concepts related to suitable binders are polymethacrylate dispersions crosslinkable by autoxidation. Essential synthesis steps of such dispersions and characteristic properties also of adequate coatings are described.Oil fatty acid structure units are enriched in the shell-region of the dispersed particles and the rest of nearly 30% is localized in the water phase as substituent of a water-soluble copolymer.
    Notes: Wäßrige Anstrichsysteme setzen sich in zunehmendem Maße durch. Als eine Entwicklungsvariante für diesbezüglich geeignete Bindemittel kommen autoxidativ vernet zende Polymethacfrylatdispersionen in Betracht. Es werden wesentliche Schritte der Synthese derartiger Dispersionen un dcharakteristische Eigenschaften auchvon Beschichtungen vorgestellt.Die Ölfettsäurestruktureinheiten sind im Schalenbereich der disperigierten Teilchen angereichert, und sie befinden sich außerden zu etwa 30% in der wäßrigen Phase als Substituenten eines löslichen Copolymeren.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1993.052040112
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  • 30
    Electronic Resource
    Electronic Resource
    A new supertough epoxy formulation with high crosslinking density (1993)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 204 (1993), S. 153-159 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Ein hochvernetztes duroplastisches Epoxidharz wurde durch “reactive blending” in Gegenwart von Bisphenol A-Polycarbonat (PC) modifiziert. FTIR-Untersuchungen zeigten, daß der Umsatz nach dem Härtungs- und Nachhärtungsprozeß durch den PC-Anteil im Blend erniedrigt wird. Darüber hinaus wurde beobachtet, daß Bruch festigkeit des Blendsystems mit wachsendem PC-Gehalt merklich steigt. Für die Phasentrennung der Unterschußkomponente während der Vernetzung wurden keine Beweise gefunden.
    Notes: A highly crosslinked thermosetting epoxy resin was modified by a reactive blending process carried out in the presence of bisphenol-A polycarbonate (PC). FTIR spectroscopy investigations demonstrated that the presence of PC in the blend decreases the reactants conversion after the curing and postcuring processes. Moreover, it was found that the fracture toughness of this blend system increases markedly by increasing the PC content in the blend. No evidence of phase separation of the minor component during the crosslinking reaction steps was observed.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1993.052040114
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  • 31
    Electronic Resource
    Electronic Resource
    Antibacterial activity of copolymers of trialkyl(4-vinylbenzyl)ammonium chlorides with acrylonitrile (1993)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 204 (1993), S. 119-125 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Die antibakterielle Wirkung von Homopolymeren von Cetyldimethyl(4-vinylbenzyl)ammoniumchlorid (VB16), Lauryldimethyl(4-vinylbenzyl) ammoniumchlorid (VB12) und TRimethyl(4-vinylbenzyl)ammoniumchlorid (VB1) und deren Copolymeren mit Acrylnitril wurde untersucht. Alle Homo- und Copolymeren wirkten bei den getesteten Bakterienarten-B. subtilis, S. aureus, E. coli und P. aeruginosa - keimtötend. Besondrs stake Effekte zeigten sich bei gram-positiven B.-subtilis- und S.-aureus-Kulturen. Die keimtötende Wirkung nahim in der Reihe VB16 〉 VB12 ≫ VB1 ab.
    Notes: Homopolymers of cetyldimethyl(4-vinylbenzyl)ammonium chloride (VB16), lauryl-dimethyl(4-vinylbenzyl)ammonium chloride (VB12), and trimethyl (4-vinylbenzyl)ammonium chloride (VB1), and copolymers of these compounds with acrylonitrile were examined for antibacterial activity using B. subtilis, S. aureus, E. coli, and P. aeruginosa. All homopolymers and copolymers showed germicidal action to the bacterias, especially strong action to gram-positive B. subtilis and S. aureus. The strength of the germicidal action of the quaternary ammonium branches was in the order: VB16 〉 VB12 ≫ VB1.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1993.052040111
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  • 32
    Electronic Resource
    Electronic Resource
    Permeation von Gasen in Polymermembranen aus thermoplastischer Stärke (1993)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 204 (1993), S. 161-175 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: The permeability of gases in films and membranes of thermoplastic starch (TPS) was investigated. The permeability- and diffusion coefficients were measured with the time-lag method on films on TPS with different plasticizer contents and at different temperatures. The experimentally determined low permeabilities were comparable to those of synthetic polymers available on the market. TPS shows at low water activities permeabilities similar to good gasbarrier materials. With increasing water content - as it is already shown for other hydrophilic polymers - the gasbarrier property of TPS gets lost. Together with earlier works on the structure and the thermodynamical behaviour of the starch, the molecular parameters and their influence on the permeability were discussed.
    Notes: Als Alternative zu den heutigen Massenkunststoffen wurde die Möglichkeit eines Einsatzes von thermoplastischer Stärke (TPS) als Barrierewerkstoff in Filmen und Membranen untersucht. Die Permeations- und Diffusionskoeffizienten wurden mitels der Induktionszeit-Methode an Filmen aus TPS in Abhängigkeit von Temperatur und Weichmachergehalt ermitelt. Die expermentell gefundence gute Gasbarriereeigen schaft der Stärke gegenüber Sauerstoff und Stickstoff wurde durch vergleichende Messungen an Handelsprodukten ergänzt. Die TPS zeigt bei nieedrigen Wassergehalten denhandelsüblichen Barrierepolymeren vergleichbare Gaspermeationsraten. Mit steigen dem Wassergehalt verliert sie- wie die meisten hydrophilen Polymere - ihre Gasbarrierewirkung.Gemeinsam mit früheren Arbeiten über die Struktur und die Eigenschaften von thermoplastischer Stärke wurden die molekularen Parameter und ihr Einfluß auf die Gasdurchlässigkeit diskutiert.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1993.052040115
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    Electronic Resource
    Electronic Resource
    Linear polythioesters, XX. Products of interfacial polycondensation of 4,4′-bis(mercaptomethyl)-biphenyl with some aliphatic and isophthaloyl dichlorides (1993)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 204 (1993), S. 139-152 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Durch Phasengrenzflächenpolykondensation von 4,4'-Bis(mercaptomethyl)biphenyl mit ausgewählten aliphatischen und isomeren Phthalsäuredichloriden wurden neue Polythioester erhalten.Um die optimalen Bedingungen der Phasengrenzflächenploykondensation zu bestimmen, wurde der Einfluß folgender Faktoren auf die reduzierte Viskosität and die Ausbeute der Polythioester ermittelt: Art der organischen Phase, Konzentration der Reagenzien. Verhältnis der wässeigen zur organischen Phase, Art und Konzentration des HCI-Akzeptors, Reaktionstemperatur und -zeit. Die Polykondensation von Dithiol mit Adipinisäuredichlorid und Isophthalsäuredichlorid wurde als Modellsystem genauer untersucht. Die Polythioesterstrukturen wurden mittels Elementaranalyse, IR-Spektroskopie und Röntgenstrukturanalyse bestätigt. Aus der thermogravimetrischen Analyse wurde die Zersetzungstemperatur, der Gewichtsverlust bei dieser Temperatur und das Maximum der Zersetzungsgeschwindigkeit erhalten. Es wurden weiterhin einige physikalisch-chemische, mechanische und dielektrische Eigenschaften ermittelt. Aufgrund der schlechten Löslichkeit der Polythioester konnten die mittleren Molekulargewichte nicht bestimmt werden.
    Notes: New polythioesters were synthesized by interfacial polycondensation of 4,4'-bis(mercaptomethyl)biphenyl with selected aliphatic and isomeric phthaloyl dichlorides.To determine optimum polycondensation conditions, the influence of the following factors on reduced viscosity and yield were studied: type of organic phase, concentration of reagents, aqueous/organic phase ratio, type and concentration of hydrogen chloride acceptor, rate of acid chloride addition, reaction temperature and reaction time.A thorough examination was carried out only for the polycondensation of dithiol with adipoyl and isophthaloyl dichlorides chosen as a model system. The structures of polythioesters were confirmed by elemental analysis, X-ray analysis and infrared spectroscopy. The temperature of initial decomposition, the percentage of its mass loss, and temperature of the fastest decomposition process from curves of differential and thermogravimetric analysis were determined. Some physicochemical, mechanical and electrical properties were determined. The molecular weights were not measured because of the low solubility of the obtained polythioesters.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1993.052040113
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  • 34
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    Electronic Resource
    Chemische Kopplung von Polystyrol und Polybutadien in Schmelzemischungen durch Verwendung eines organischen Sulfonylazids (1993)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 204 (1993), S. 177-189 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Investigations on chemical coupling of heterogeneous polystyrene-polybutadiene blends were carried out using an organic sulfonylazide. The coupling process was realized in the melt mixing process on a laboratory melt kneader. The efficiency of the coupling agent was evaluated by IR-spectroscopical, microscopical, and dynamic-mechanical analysis and by mechanical properties of the blends. The graft copolymers forming in the melt cause an increase of the stress-strain properties and the impact strength of the blends.
    Notes: Es wurden Untersuchungen zur chemischen Kopplung heterogener Polystyrol-Polybutadien-Blends bei Einsatz eines organischen Sulfonylazids während des Schmelzemischens im Laborinnenmischer angestellt. Die Wirksamkeit des Kopplungsagens wurde anhand infrarotspektroskopischer, mikroskopischer und dynamisch-mechanischer Analysen sowie anhand des merchanischen Eigenschaftsbildes der Belends beurteilt. Die sich in der Schmelze bildenden Pfropfcopolymeren führen zu einer Erhöhung der Phasenwechselwirkungen un dami zu einer Verbesserung der Festigkeits- und Zähigkeits-eigenschaften der Blends.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1993.052040116
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  • 35
    Electronic Resource
    Electronic Resource
    Interpenetrierende Polymernetzwerke aus ungesättigten Polyesterharzen und Dian-Dicyanat (1993)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 205 (1993), S. 19-30 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Interpenetrating polymer networks (IPN) were obtained by the simultaneous crosslinking of unsaturated polyester resins and Bisphenol A dicyanate. The copolymerization of the unsaturated polyester with styrene occurred according to the radical mechanism, whereas Bisphenol A dicyanate underwent a cyclotrimerization, thus forming a polytriazine (polycyanurate) network. The IPNs are characterized by elevated glass transition temperature and increased mechanical strength in comparison with corresponding unsaturated polyester resin without Bisphenol A dicyanate.
    Notes: Interpenetrierende Polymernetzwerke (IPN) wurden durch die gleichzeitige Vernetzung ungesättigter Polyesterharze und Dian-Dicyanat erhalten. Die Copolymerisation von ungesättigtem Polyester mit Styrol erfolgte nach dem radikalischen Mechanismus, während das Dian-Dicyanat cyclotrimerisierte, wodurch sich ein Polytriazin(Polycyanurant)- Netzwerk bildete. Die IPN zeichnen sich durch erhöhte Glastemperatur und mechanische Festigkeit im Vergleich zum entsprechenden ungesättigten Polyesterharz ohne Dian-Dicyanat-Zusatz aus.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1993.052050102
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  • 36
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    Electronic Resource
    Zur Bestimmung des Modifikatorgehaltes von Stearinsäure- und Titanat-modifizierten CaCO3-Füllstoffen (1993)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 205 (1993), S. 1-17 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Simultaneous TG/DTA analysis has been used for determination of surface coating of CaCO3-filler with stearic acid (STS) or isopropyl triisostearoyl titanate (titanate). The method has been used for several model samples as well as for commercial fillers with surface coating concentrations of 0-2.7% for stearic acid and 0-4.0% for titanate. A reliable agreement of surface coating concentration of STS determined by simultaneous TG/DTA analysis and C-analysis was achieved if the temperature range of decomposition of the surface-modifying agent was taken into account. This was found for stearic acid between 180 and 450°C (〉1% STS at 500°C) and for titanate between 120 and 450°C (〉 1% titanate at 500°C) from the slopes of the TG- and DTA curves. The mass loss in the range of decomposition is equal to the concentration of surface coating in the case of STS. For titanate-modified fillers an amount of 10% of the mass loss must be added. For determination of surface coating of CaCO3-fillers having higher contents of humidity (〉 0.2%) it is necessary to know this amount, otherwise the STS determination has to be performed by oxidation heat.
    Notes: Zur Bestimmung des Modifikatorgehaltes von Stearinsäure(STS)-bzw. Isopropyltriisostearyltitanat(Titanat)-modifizierten CaCO3-Füllstoffen wurde die simultane TG/DTA-Analyse genutzt. die Methode wurde für Modellproben sowie für verschiedene kommerzielle Füllstoffe mit einem Konzentrationsbereich von 0 - 2,7% STS bzw. 0 - 4% Titanat angewendet. Eine ausreichende Übereinstimmung der Modifikatorkonzentrationen für STS, bestimmt durch simultane TG/DTA-Analyse sowie eine C-Analyse, wird erreicht, wenn der Zersetzungsbereich des Modifikators berücksichtigt wird. Dieser liegt für Stearinsäurezwischen180°C und 450°C (bei STS 〉 1% bei 500°C) und für Isopropyltriisostearyltitanat zwischen 120 und 450°C (Titanat 〉 1% bei 500°C) und wird aus dem Anstieg der TG-bzw. DTA-Kurve erhalten. Der diesem Zersetzungsbereich zuzuordnende Masseverlust entspricht bei STS-modifizierten Füllstoffen dem Stearinsäuregehalt. Bei Titanat-modifizierten CaCo3-Füllstoffen ist ein Betrag von 10% des Masseverlustes hinzuzufügen. Für die Modifikatorgehaltsbestimmung von CaCo3-Füllstoffen, die einen höheren Feuchtigkeitsgehalt (〈 0,2%) aufweisen, ist die Kenntnis dieser Größe notwendig, anderenfalls ist die STS-Bestimmung über die Oxidationswärme zu realisieren.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1993.052050101
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    Electronic Resource
    Announcements (1993)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 204 (1993), S. 191-191 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1993.052040117
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  • 38
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    Electronic Resource
    Removal of methyl orange by systems of insoluble poly(glycidyl methacrylate)-g-tetraethylene-pentamine and -g-polyethyleneimines (1993)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 205 (1993), S. 31-45 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Die Entfernung von Methylorgane (MO) aus Wasser oder einer Pufferlösung (pH7) durch Adsorption and Reaktionsprodukten von Poly(gylcidylmethacrylat) (PGMA) mit Tetraethylenpentamin oder mit einem Polyethylenimin mit einem Molekulargewicht von 600 (PE1600) wurde untersucht. Das Adsorptionsverhalten läßt sich besser mit der Freundlich-Gleichung als mit der Klotz-Gleichung beschreiben. Adsorptionsgeschwindigkeit und adsorbierte Menge waren in Wasser größer als in der Pufferlösung, in der durch Salzbildung die Adsorption vermindert wird. Die adsorbierte Menge hängt nicht immer von der Menge der an PGMA gebundenen PE1600-Gruppen ab.
    Notes: A study was made of the removal of methyl orange (MO) solutes in water and in a pH 7 buffer solution by the reaction products of insoluble poly(glycidyl methacrylate) (PGMA) with tetraethylenepentamine (TEP) or polyethylenimine (PEI) having molecular weight of about 600 (PEI600). An examination was made of the adaptability of the Freundlich adsorption formula and the Klotz equation to removal behaviour of these polymers, which was noted to conform better to the Klotz equation than to the Freundlich adsorption formula. The removal rate and the amount removed were greater in water than in a pH 7 buffer solution, and decreased due to coexisting salts. The amount removed does not always depend on the amount of PEI600 groups bound to PGMA.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1993.052050103
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  • 39
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    Electronic Resource
    Effect of strain rate and temperature on stress-strain properties of EVA-LDPE blends and the mechanism of strain hardening (1993)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 205 (1993), S. 59-74 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Das Zug-Dehnungs-Verhalten von verschiedenen Blends aus Poly(ethylen-co-vinylacetat) (EVA, 28 wt.-% VA-Anteil) und Polyethylen (LDPE) wurde bei unterschiedlichen Dehnungsgeschwindigkeiten und Temperaturen untersucht. Die Zug-Dehungs-Kurven solcher semikristalliner Polymerblends bestehen aus drei Teilen - elastischer oder Hookescher Bereich, Bereich des Aneinanderabgleitens der Ketten sowie Dehnungshärtungsbereich. Eine Verminderung der Dehnungsgeschwindigkeit bewirkt eine Vergrößerung des Dehnungshärtungsbereiches. Die Erhöhung der Meßtemperatur beeinflußt der Dehnungshärtung bei erhöhten Temperaturen vom Kristallschmelzpunkt der Hauptkomponente des Blends abhängt. Röntgen- und DSC-Untersuchun-gen zeigen, daß die Dehnungshärtung von einer Veränderung der Kristallistruktur in LDPE und LDPE-reichen Blends ausgeht, während sie in EVA und EVA-reichen Blends auf eine induzierte Kristallisation in der amorphen Phase zurückzuführen ist.
    Notes: Stress-strain behaviour of different blends of poly(ethylene-co-vinyl acetate) (EVA) (28 wt.-% VA content) and low density polyethylene (LDPE) is studied under various strain rates and temperatures. It is found that stress-strain plots of such semicrystalline polymer blends consist of three parts, namely, elastic or Hookeian region, region of chain slippage and region of strain hardening. Decrease in strain rate has an increasing effect on the strain hardening region. Increase in measurement temperature adversely affects the whole stress-strain plot. It is apparent from the study that at an elevated temperature the process of strain hardening is dependent on the crystalline melting point of the major component in the blend. The X-ray and DSC studies reveal that the process of strain hardening is mainly due to a change in internal order of crystallites in LDPE and LDPE-rich blends, whereas in EVA and EVA-rich blends it is due to induced crystallization in the amorphous phase.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1993.052050105
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  • 40
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    Electronic Resource
    Effect of structure and composition on physico-mechanical properties of methyl methacrylate/alkyl (meth)acrylate copolymers (1993)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 205 (1993), S. 47-58 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Methylmethacrylat (MMA) mit einem Prepolymergehalt von 6-8% wurde mit unterschiedlichen Anteilen (1-20%) 2-Ethylhexylmethacrylat (EMMA), n-Hexylmethacrylat (HMA), 2-Ethylhexylacrylat (EHA) oder n-Hexylacrylat (HA) copolymerisiert. Aus den erhaltenen Copolymeren wurden Folien hergestellt, an denen der Einfluß der Copolymerstruktur auf Lichtdurchlässigkeit, Dichte und mechanische Eigenschaften ermittelt wurde. zugsfestigkeit and Speichermodul nahmen mit zunehmendem Comonomergehalt ab. Die Dehnung stieg im Fall von MMA/EHA- und MMA/HA-Copolymerfolien mit 15 und 20 Gew.-% Comonomeranteil merklich an. Mittels DMTA wurde die Erweichungstemperatur der Copolymeren bestimmt. Die HDT und die Erweichungstemperatur nahmen unter Biegebelastung mit steigendem Comonomergehalt de Copolymeren ab.
    Notes: The paper describes the fabrication of cast acrylic sheets by copolymerizing a prepolymer syrup of methyl methacrylate (MMA) with varying amounts (1-20 wt.-%) of 2-ethylhexyl methacrylate (EHMA), n-hexyl methacrylate (HMA), 2-ethylhexyl acrylate (EHA) and n-hexyl acrylate (HA). The effect of structure of copolymer on light transmittance, density and mechanical properties was evaluated. Tensile strength and storage modulus decreased with increasing comonomer content. Strain increased significantly in the case of MMA/EHA and MMA/HA copolymer sheets having 15 and 20 wt.-% of comonomer. Softening temperature of copolymer samples was determined using dynamic mechanical thermal analysis. Heat deflection temperature under flexural load and softening temperature decreased with increasing comonomer content in copolymer.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1993.052050104
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  • 41
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    Electronic Resource
    Preparation and properties of silicon-containing copolymers for near-UV resists, IIPart I, cf.12.. Poly[(N-(4-hydroxyphenyl)maleimide)-alt-(p-trimethylsilyl-α-methylstyrene)] (1993)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 205 (1993), S. 75-90 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Poly[(N-(4-hydroxyphenyl)maleimid)-alt-(p-trimethylsilyl-a-methylstryol)] (a-PHTMMS) und einige N-(4-hydroxyphenyl)maleimid-alt-p-trimethylisilyl-a-methylstyrol-enthaltende Copolymere wurden synthetisiert, um mit Diazonaphtochinonsulfonat neue Resists für den nahen UV-Bereich (DNS) zu entwickeln.Durch die kettenversteifende Wirkung der Maleimid-Gruppe wurde eine hohe thermische Stabilität mit einer Glasübergangstemperatur von 240°C und einer Zersetzungstemperatur von 425°C erreicht. Daraus hergestellte lithographische Biler widerstanden noch bei 250°C thermischer Verformung. Die hergestellten siliciumhaltigen Resists wurden auch als oberste Schicht in zweischichtigen Materialien für die Anwendung in der Mikrolithographie untersucht.
    Notes: Poly[(N-(4-hydroxyphenyl)maleimide)-alt-(p-trimethylsilyl-α-methylstyrene)] (α-PHTMMS) and several N-(4-hydroxyphenyl)maleimide -alt-p-α-methylstyrene related copolymers were synthesized for novel positive near-UV resists containing diazonaphthoquinone sulfonate (DNS). The chain-stiffening effect of the maleimide group was responsible for high thermal resistance. Thus, a high glass transition temperature of 240°C and thermal decomposition temperature of 425°C were obtained. Lithographic positive images were obtained which resisted thermal deformation at 250°C. The prepared silicon-containing resists were also used as the top imaging layer of a bilayer resist for microlithographic application.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1993.052050106
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  • 42
    Electronic Resource
    Electronic Resource
    On the polymerization of styrene in the presence of some benzanthrone dyes (1993)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 205 (1993), S. 91-95 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Die Polymerisation von Styrol in Anwesenheit von Fluoreszenzfarbstoffen, Derivaten des Benzanthrons, wurde untersucht. Die Abhängigkeit der Polymerisationsgeschwindigkeit des Styrols vom Charakter des Farbstoffs wurde ermittelt. Spektrophotometrisch wurde festgestellt, daß 70-80% des Farbstoffs in das Polymere eingebaut werden, ohne daß dies zu einer bedeutenden Veränderung des Molekulargewichts und der Molekulargewichtsverteilung führt.
    Notes: The polymerization of styrene in the presence of some fluorescent dyes, benzanthrone derivatives, has been investigated. The dependence of the polymerization rate of styrene on the character of the dye was determined. It was found spectrophotometrically that 70 - 80% of the dye reacted in the polymerization, thus the coloured fluorescent polymers were obtained. They are resistant to wet treatment and decolouration by solvent. The incorporation of the dye into the polymer chain does not significantly affect the molecular weight and polydispersity of the coloured polymers.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1993.052050107
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  • 43
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    Electronic Resource
    The influence of sepiolite on the dynamic moduli and thermal transition of compatible and incompatible blends based on poly(vinylidene fluoride) (1993)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 205 (1993), S. 97-106 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Im vorliegenden Beitrag wird über die Veränderungen der dynamischen Moduli und der thermiscen Übergänge von Polyvinylidenfluorid in kompatiblen Blends mit Polymethylmethacrylat und in nicht kompatiblen Blends mit Polystyrol berichtet. Die Wirkung des Sepioliths auf die Kompatibilität dieser Blends wurde untersucht.
    Notes: This paper reports on a study of dynamic moduli and thermal transitions of poly(vinylidene fluoride) in compatible blends with poly(methylmethacrylate) and in non-compatible blends with polystyrene. The effects of sepiolite on the compatibility of these blends have been studied.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1993.052050108
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  • 44
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    Electronic Resource
    Improvement of ageing properties of rubber films prepared from radiation-vulcanized natural rubber latex (1993)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 205 (1993), S. 107-115 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Die Strahlungsvulkanisation von Naturgummilatex (NRL) mit n-Butylacrylat führt bei daraus hergestellten Filmen zu höheren Zugfestigkeiten. Die Alterungseigenschaften von strahlungsvulkanisiertem Naturgummi (RVNRL) wurden in Gegenwart unterschiedlicher Antioxidantien untersucht. Um für die Filme aus RVNRL geeignete Antioxidantien zu finden, wurde die Gelfraktion mit Xylol in Gegenwart von 1-Gew.-% Antioxidans unter einem Luftstrom extrahiert. Antioxidantien, die während der Extraktion einer durch oxidativen Abbau bedingten Verringerung des Gelanteils entgegenwirken, sind für die Alterungssuntersuchungen mit RVNRL geeignet. Es zeigte sich, daß Tris(nonylphenyl)phosphit (Nonflex TNP) und 2,5-Di-tert-amylhydrochinon (Antage DAH) unter 12 getesteten Antioxidantien am effektivsten waren.
    Notes: Radiation-vulcanization of natural rubber latex (NRL) with n-butyl acrylate gives a higher tensile strength for films obtained after casting. The ageing properties of radiation-vulcanized natural rubber in the presence of various antioxidants have been investigated. In order to find out suitable antioxidants for radiation-vulcanized natural rubber latex (RVNRL) films, extraction of the gel fraction was carried out in xylene with 1 wt.-% antioxidant and air bubbling. Antioxidants which give less reduction in gel fraction due to oxidative degradation during extraction are effective for ageing tests of RVNRL films. It was found that tris(nonylated phenyl) phosphite (Nonflex TNP) and 2,5-di-tert-amylhydroquinone (Antage DAH), among 12 different antioxidants tested, were the most effective antioxidants for RVNRL films.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1993.052050109
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    Electronic Resource
    Electronic Resource
    Porous ion-exchange membranes, 2Part 1 cf.1.. Effect of adhesion promoters (1993)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 205 (1993), S. 131-139 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Stearinsäure bzw. Dibutylphthalat wurden als Adhäsionsverbesserer zu mit Calciumcarbonat gefüllten ternären Blends, bestehend aus einem Polyethylen/Poly(strol-co-divinylbenzol)-Interpolymeren und Polypropylen, zugegeben. Daraus wurden nach einem bereits beschriebenen Verfahren poröse Ionenaustauschermembranen (PIEM) hergestelt. Die Adhäsionsverbesserer führen dabei zu einer beträchtlichen Erhöhung des Porendurchmessers, da die Diffusion von Chlorsulfonsäure zu den Calciumcarbonatkörnern und damit die Bildung großer Mengen Kohlendioxid erleichtert wird. Andere PIEM-Eigenschaften werden nicht sigifikant beeinflußt.
    Notes: The previously described preparation of porous ion-exchange membranes (PIEM's) from the ternary blends of polyethylene interpolymer with poly(styrene-co-divinylbenzene) and polypropylene and calcium carbonate filler has been supplemented with the use of stearic acid and dibutyl phthalate as adhesion promoters. It was noted that both promoters govern the huge increase of pore diameter without any significant disturbances in the other PIEM's properties. The facilitating effect of chlorosulfonic acid diffusion toward calcium carbonate grains and large amounts of carbon dioxide volatilization was concluded. This is the basic point of pore creation to be discussed in this paper.
    Additional Material: 1 Ill.
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    URL: http://dx.doi.org/10.1002/apmc.1993.052050111
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    Macroporous membranes, IV. Synthesis and properties of poly[(2,3-epoxypropyl methacrylate)-co-(N-vinyl-2-pyrrolidone)-co-(ethylene dimethacrylate)] membranesPart III see1. (1993)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 205 (1993), S. 141-149 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Makroporöse Membranen aus Terpolymeren von 2,3-Epoxypropylmethacrylat, N-Vinyl-2-pyrrolidon und Ethylendimethacrylat, wurden durch radikalische Suspensionscopolymerisation hergestellt und danach mit Ammoniak modifiziert. Charakteristische Eigenschaften der Membranen wei Porosität, spezifische Oberfläche, Porengröße, Wasserdurchlässigkeit und mechanische Eigenschaften wurden bestimmt. Ein niedriger Gehalt an N-Vinyl-2-pyrrolidon verbessert die mechanischen Eigenschaften der Membranen. Der Mechanismus der Bildung der makroporösen Struktur und der Heterogenitäten wird diskutiert.
    Notes: Macroporous membranes based on terpolymers of 2,3-epoxypropylmethacrylate, N-vinyl-2-pyrrolidone, and ethylenedimethacrylate were prepared by radical suspension copolymerization and subsequently modified with ammonia. The membranes were characterized by their porosity, specific surface area, pore size, water permeability and mechanical properties. The low content of N-vinyl-2-pyrrolidone improves the mechanical properties of the membranes. The mechanism of formation of the macroporous structure and heterogeneities is discussed.
    Additional Material: 4 Ill.
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    URL: http://dx.doi.org/10.1002/apmc.1993.052050112
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    Photomodifizierung von Ultrafiltrationsmembranen, 2. Ultrafiltrationseigenschaften von mit Arylaziden photochemisch modifizierten Polyacrylnitril-membranenTeile dieser Arbeit wurden präsentiert auf der 23. Hauptversammlung der Gesellschaft Deutscher Chemiker, München, 9.-13.9.1991. Teil 1 cf. Angew. Makromol. Chem. 210 (1993) 69. (1993)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 210 (1993), S. 97-117 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: The aim of the studies was to characterize the ultrafiltration properties of a variety of photochemically modified membranes, made by a new approach starting with two types of PAN-UF membranes and using nine aromatic azides bearing different more or less hydrophilic or hydrophobic substituents. The influence of the surface functionalization (hydrophilization, introduction of charges/hydrophobization) realized by this means onto the water permeability, the dextrane selectivity, and the permeabilities during and after UF, resp., after simple contact with solutions of ovalbumine and lysozyme was the major subject. Modified membranes made using the aryl azides with hydrophilic groups, 4-azidobenzoic acid, Ib, (4-azidophenyl)trimethylammonium iodide, If, sodium (4-azido)-benzene sulfonate, Id, showed enhanced water fluxes and reduced dextrane retention. All the other azides caused reduced water permeability, enhanced dextrane selectivity, and significant flux reductions as a consequence of contact with ovalbumin solutions (pH = 5.0). The strongest effects were achieved with the two expecially hydrophobic compounds, 2-naphthyl azide, Ih, and 2-naphthoyl azide, IX. On the other hand, a pronounced positive effect of photo-modification on the protein fouling behaviour became evident in the UF of lysozyme (0.05%, pH = 10.5). Using the membranes modified with Id a much higher filtrate flux (Jv = 48.1 l/m2h) was observed as compared with the original PAN membrane (Jv = 13.1 I/m2h). The perspectives and the limitations of the developed modification strategy are discussed.
    Notes: Nach einem neuartigen Verfahren mit Hilfe von neun, mit verschieden hydrophilen bzw. hydrophoben Substituenten synthetisierten aromatischen Aziden unterschiedlich photochemisch modifizierten Polyacrylnitril-Ultrafiltrations-Membranen wurden in UF-Versuchen charakterisiert. Dabei sollte der Einfluß der so erzielten Oberflächenfunktionalisierungen (Hydrophilierung, Einführung von Ladungen oder Hydrophobierung) auf das Trennverhalten (Wasserdurchläassigkeit und Selektivitäat für Dextrane, Permeabilität während und nach der UF bzw. nach einfachem Kontakt mit Ovalbuminund mit Lysozym-Lösungen) studiert werden. Die Modifizierung mit den Arylaziden, die hydrophile Gruppen enthalten (4-Azidobenzoäure, Ib, (4-Azidophenyl)-tri-methylammoniumiodid, If, Natrium-4-azidobenzolsuflfonat, Id), führt zu einer erhöhten Durchlässigkeit der Membranen für Wasser und Dextrane. Alle anderen Azide, darunter besonders stark die deutlich hydrophoben 2-Naphthoylazid, Ih, und 2-Naphthoylazid, IX, verringern die Wasserpermeabilität, erhöhen das Rückhaltevermögen für Dextrane und verstärken die Effekte der Wechselwirkungen mit Ovalbumin (pH = 5,0). Das wird in Flußreduzierungen verglichen mit der unmodifizierten PAN-UF-Membran sichtbar. Ein positiver Effekt der Photomodifizierung wird besonders deutlich bei der UF von Lyasozym (0,05%, pH = 10,5) mit der mit Id modifizierten Membran (Jv = 48,1 l/m2h) im Vergleich zur Ausgangs-Membran (Jv = 13,1 1/m2h). Die Perspektiven und die Grenzen des Modifizierungsverfahrens werden abschließend diskutiert.
    Additional Material: 6 Ill.
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    URL: http://dx.doi.org/10.1002/apmc.1993.052100108
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    Membranen aus poly(p-phenylen-1,3,4-oxadiazol) (1993)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 210 (1993), S. 197-205 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: For solving specific problems of separation, high demands on membrane materials will be made in relation to thermal stability and resistance in a wide pH-range and against organic solvents. Membranes from poly(p-phenylen-1,3,4-oxadiazole) are prepared by different methods and their separation properties in ultrafiltration are investigated.
    Notes: Poly(p-phenylen-1,3,4-oxadiazol) (POD) ist aufgrund seiner thermischen Stabilität, pH- und Lösungsmittelbeständigkeit ein interessanter Werkstoff zur Herstellung von Membranen. Die Herstellung von POD-Membranen und deren Trenneigenschaften im Prozeß der Ultrafiltration werden untersucht.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1993.052100115
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    Poly(sulfide sulfone) by activated nucleophilic displacement polymerization (1993)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 211 (1993), S. 79-87 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Ein Poly(sulfidsulfon) wurde durch aktivierte nucleophile Substitution der Nitrogruppen von Bis(4-nitrophenyl)sulfon mit wasserfreiem Natriumsulfid bei 200 C in N-Methyl-2-pyrrolidon (NMP) hergestellt. Das Polymere löst sich in NMP, Dimethylformamid (DMF), Dimethylsulfoxid und anderen hochpolaren Lösungsmitteln. Das Molekulargewicht des Polymeren mit einer inhärenten Viskosität von 15 ml/g bei 30°C in DMF wurde mittels 1H-NMR-Spektroskopie zu Mn = 2500 bestimmt. Die Glastemperatur liegt bei ca. 73°C; der Veraschungsrückstand bei 600°C in Luft beträgt 36%, der Sauerstoffindex (LOI) ca. 37.
    Notes: A poly(sulfide sulfone) was synthesized by activated nucleophilic displacement reaction between bis(4-nitrophenyl)sulfone and anhydrous sodium sulfide at 200°C in N-methyl-2-pyrrolidone (NMP). The polymer is soluble in NMP, dimethylformamide, dimethylsulfoxide and other highly polar solvents. The molecular weight of the polymer (M̄n = 2.500) having an inherent viscosity of 15 mL/g at 30°C in DMF was determined by 1H-NMR spectroscopy. The polymer has a glass transition at approx. 73°C and char residue of 36% at 600°C in air. The limiting oxygen index of the polymer is ∼37.
    Additional Material: 5 Ill.
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    URL: http://dx.doi.org/10.1002/apmc.1993.052110107
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    Agitation scale-up model for the suspension polymerization of vinyl chloride (1993)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 211 (1993), S. 35-51 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Es wurden Untersuchungen durchgeführt, um ein auf experimentellen Ergebnissen basierendes mathematisches Modell zu entwickeln, welches die Durchmischung und andere Polymerisationsparameter mit der Partikelgröße von PVC korreliert und die Grenzen der Rührgeschwindigkeit in einem definierten Rührersystem festlegt.Dazu wurde eine Computer-Regressionsanalyse von etwa 30 in Reaktoren von 10L bis 27 m3 Volomen durchgeführten Vinylchlorid-Polymerisationen berechnet. Die Partikelgröße (d50) hängt dabei ab von den Polymerisationsparametern Rührerdurchmesser (D), Rührergeschwindigkeit (N), Durchmesser des Reaktorbehälters (T), Flüssigkeitsstand (H1) und Volumen des Reaktorbehälters (V) (NWe = Weber-Zahl): d50 = 4346.8 (N)-0.905 (D)-0.901 (T)-0.514 (H1)-0.131d50/D = 273292.1 NWe-0.51 undNmin = 3049.1 D-1.1 (T/D)-0.113In diesen Gleichungen sind nur die Werte 3049, 1, -0,113, 4346, 8 und 273 292, 1 abhängig von der Zusammensetzung des Polymerisationsgemisches. Wird dieses geändert, müssen diese Variablen anhand von einer oder zweier Polymerisationen im Pilotmaßstab ermittelt werden, um die Beziehungen an die neue Zusammensetzung anzupassen und so eine Übertragung auf einen größeren Reaktor zu ermöglichen.
    Notes: Studies were carried out to develop a mathematical model based on experimental results to correlate agitation and other polymerization parameters with the particle size of PVC and to specify the limits of agitation speed within the defined agitation system. Computer regression analysis of about 30 vinyl chloride polymerizations in reactors with 10 L to 27 m3 tank volume are carried out. The particle size of PVC (d50) is correlated to various polymerization parameters such as impeller diameter (D), impeller speed (N), reactor tank diameter (T), liquid height (H1) and tank volume (V) (NWe = Weber number): d50 = 4346.8 (N)-0.905 (D)-0.901 (T)-0.514 (H1)-0.131d50/D = 273292.1 NWe-0.51Nmin = 3049.1 D-1.1 (T/D)-0.113In these equations only the values 3049.1, -0.113, 4346.8 and 273 292.1 depend on the recipe. When the recipe is changed these variables must be determined by one or two bench-scale polymerizations to adjust the correlations to the new recipe conditions so that they can be also used for scale-up purposes with the new recipe.
    Additional Material: 2 Ill.
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    URL: http://dx.doi.org/10.1002/apmc.1993.052110104
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    Modelluntersuchungen zur topologie der härtung geordneter epoxidnetzwerke (1993)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 211 (1993), S. 61-77 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: 4-Phenyl-4-(2,3-expoxypropyl)benzoate (I) can be cured to thermoset networks with a different degree of order by using isomeric aminophenyl aminobenzoates II to V as curing agents. The formation of intermediates during the curing reaction was studied by means of model compounds. From the reaction of the monoamino-substituted phenylbenzoates VI to IX the reactivities for the primary and the secondary aminoprotons towards epoxide was determined. The kinetic data were used for a stepwise simulation of the curing reaction. Arguments were found that in case of diamines with 4-aminobenzoate structure well ordered intermediates are formed, which crosslink in an early stage of the reaction.
    Notes: Die Härtung von 4-Phenyl-4-(2,3-epoxypropoxy)benzoat (I) mit den isomeren Aminophenylaminobenzoaten II bis V führt zu unterschiedlich geordneten Epoxidnetzwerken. Die Bildung verschiedener Intemediate während der Härtungsreaktion wurde anhand von Modellverbindungen studiert. Aus der Reaktion der monoamino-substituierten Phenylbenzoate VI bis IX mit Epoxid wurden die Reaktionskostanten für die Addition an das primäre und das sekundäre Wasserstoffatom der Aminogruppen bestimmt. Die kinetischen Daten lassen sich für eine schrittweise Simulation des Härtungsverlaufs verwenden. Es wurden Argumente dafür gefunden, daß sich bei Verwendung der Amine mit 4-Aminobenzoat-Strukturen gut geordnete, schnell vernetzende Intermediate bilden.
    Additional Material: 5 Ill.
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    URL: http://dx.doi.org/10.1002/apmc.1993.052110106
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    Modelling the polymerization of 1,3-butadiene in solution with a neodymium catalyst (1993)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 211 (1993), S. 89-101 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Die diskontinuierliche Polymerisation von Butadien in Hexan bei 45°C mit einem in-situ-aktivierten Ziegler-Katalysator aus Neodymversatat, Ethylaluminiumsesquichlorid und Triisobutylauminium wurde untersucht. Die Polymerisationsgeschwindigkeit wurde durch Dichtemessungen verfolgt. Zur Beschreibung der Polymerisationskinetik bei verschiedenen Katalysatorzusammensetzungen wurde ein mathematisches Modell entwickelt. Bei einem molaren Aluminium/Neodym-Verhältnis über 40 kann mittels Gelpermeationschromatographie eine bimodale Molmassenverteilung beobachtet werden, was zu der Annahme führt, daß im Polymerisationssystem mehr als eine aktive Spezies anwesend ist.
    Notes: The batch polymerization of butadiene in hexane with an in-situ-activated Ziegler-Catalyst containing neodymium versatate, ethylaluminium sesquichloride and triisobutylaluminium was studied at 45°C. The rate of polymerization was determined by online density measurements. A mathematical model has been developed which is able to describe the kinetics of polymerization at different catalyst ratios. At molar ratios of aluminium/neodymium above 40 a bimodal molar mass distribution can be observed by gel permeation chromatography which leads to the assumption of more than one active species being present in the polymerization system.
    Additional Material: 8 Ill.
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    URL: http://dx.doi.org/10.1002/apmc.1993.052110108
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    Removal of escherichia coli from water by systems based on insoluble poly(glycidyl methacrylate)-G-tetraethylenepentamine and -G-polyethylenimine (1993)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 206 (1993), S. 1-9 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Die Fähigkeit von zwei Polymeren zur Adsorption von Escherichia coli (E. coli) in sterilisierter physiologischer Kochsalzlösung wurde untersucht. Als Polymere wurden die Reaktionsprodukte von unlöslichen Poly(glycidylmethacrylat)-Kügelchen (PGMA) mit Tetraethylenpentamin (TEP) bzw. Polyethylenimin mit einem Molekulargewicht von 60 (PEI600) verwendet. Die Zahl der vermehrungsfähigen Zellen nahm in Gegenwart dieser Polymeren ab. Elektronenmikroskopisch konnte nachgewiesen werden, daß diese Abnahme durch Adsorption der Bakterien auf der Polymeroberfläche verursacht wird. Die Koeffizienten (D) der Abnahme der vermehrungsfähigen Zellen (E. coli) betragen 53 und 62 ml g-1 h-1 für PGMA-TEP bzw. PGMA-PEI600. Sie werden mit den Koeffizienten bereits untersuchter Polymerer verglichen.
    Notes: A study was made of the removal of Escherichia coli (E. coli) from water by systems based on insoluble poly(glycidyl methacrylate)-g-tetraethylenepentamine and -g-polyethylenimine, i.e., the reaction products of insoluble poly(glycidyl methacrylate) (PGMA) beads with tetraethylenepentamine (TEP) or polyethylenimine having molecular weights of about 600 (PEI600). The polymers (PGMA-TEP and PGMA-PEI600) were brought into contact with E. coli in sterilized physiological saline. These polymers made the viable cell numbers decrease in this medium. It was confirmed by observation of polymer surfaces with a scanning electron microscope that this decrease was caused by adsorption of the bacterial cells onto these polymers. The decrease coefficients of viable cell numbers (D) for E. coli by these polymers were 53 ml g-1 h-1 for PGMA-TEP and 62 ml g-1h-1 for PGMA-PEI600, being compared with D by other polymers studied previously.
    Additional Material: 4 Ill.
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    URL: http://dx.doi.org/10.1002/apmc.1993.052060101
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    Thermal dehydrochlorination of PVC in the presence of rubber seed oil (1993)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 206 (1993), S. 11-20 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Die Dehydrochlorierungsgeschwindigkeit von PVC in Gegenwart von Gummisamenöl (RSO), epoxydiertem Gummisamenöl (ERSO) sowie Metallseifen der daraus hergestellten Fettsäuren wurde unter Stickstoff gemessen. Die Anfangsgeschwindigkeiten der Dehydrochlorierung und die Zeit bis zu einem Abbauumsatz von 1% zeigen einen stabilisierenden Effekt der RSO-Derivate mit der Reihenfolge ERSO-Metalseifen 〈 RSO-Metalliseifen 〈 ERSO 〈 RSO.
    Notes: Dehydrochlorination rates of PVC in nitrogen atmosphere were determined in the presence of rubber seed oil (RSO), epoxidized rubber seed oil (ERSO), barium soap of rubber seed oil fatty acids and barium soap of epoxidized fatty acid of rubber seed oil. The initial rates of dehydrochlorination and the time required for the degradation to attain 1% conversion showed that the rubber seed oil derivatives exert a stabilizing effect on the degradation of PVC. The order of the stabilizing effect was found to be metal soaps of ERSO 〈 metal soaps of RSO 〈 ERSO 〈 RSO.
    Additional Material: 6 Ill.
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    URL: http://dx.doi.org/10.1002/apmc.1993.052060102
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    Wirkung von Diisocyanat als reaktiver Koppler in TPU/PA6-Blends (1993)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 206 (1993), S. 21-38 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: To improve materials performance like the temperature of deformation under flexural load of thermoplastic polyurethanes (TPU) blending with thermoplastics is sensible. A good compatibilization and phase adhesion of thermodynamical incompatible blend-components can be achieved by the use of the right coupling agents. In the case of blends with TPU and PA6 diisocyanate is given into the melt during the extrusion. Through the chemical reactions effects of compatibilization are achieved in the cases of blends with polyesterpolyurethanes and PA6 produced by extrusion and injection moulding and by reactions in solution, too. These could be perceived as consequence of MDI-initiated reactions within the phase boundary layer. The possible reactions with the PA6-phase will be discussed by the use of a model-system made in solution. No effects of compatibilization by MDI could be proved in the polyetherpolyurethan/PA6-system. The chemical characterization of the blends was realized by GPC and FTIR whereas the properties of the morphology are proved with the help of DSC, DMA and transmission electron microscopy (TEM).
    Notes: Zur Verbesserung der Werkstoffeigenschaften von thermoplastischen Polyurethanen (TPU), wie etwa der Wärmeformbeständigkeit, ist es sinnvoll, ein Blending mit Thermoplasten vorzunehmen. Eine gute Phasenverträglichkeit und Phasenhaftung bei thermodynamisch unverträglichen Blendkomponenten kann durch geeignete reaktive Koppler erreicht werden. Bei den Blends aus TPU and PA6 wird Diisocyanat während der Extrusion in der Schmelze eingebracht. Durch die ablaufenden chemischen Reaktionen werden bei extrudierten und verspritzten Blends und bei aus der Lösung erzeugten Systemen aus Polyesterpolyurethan und PA6 verträglichkeitsverbessernde Wirkungen erreicht. Diese wurden als Folge von mit 4,4′-Diphenylmethandiisocyanat (MDI) initiierten Reaktionen in der Grenzschicht erkannt, wobei die möglichen Reaktionen mit der PA6-Phase anhand eines Modellsystems aus der Lösung diskutiert werden. Bei Blends aus Polyetherpolyurethan und PA6 wurde keine Verträglichkeitsvermittlung durch MDI nachgewiesen. Die chemische Charakterisierung der Blends erfolgte durch GPC und FTIR, während die morphologischen Eigenschaften mittels DSC, DMA und Elektronenmikroskopie dokumentiert wurden.
    Additional Material: 10 Ill.
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    URL: http://dx.doi.org/10.1002/apmc.1993.052060103
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    Kinetics analysis of the curing of a diepoxy-diamine system (1993)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 206 (1993), S. 39-52 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Die Reaktion von 4,9-Dioxa-1,12-dodecandiamin (DDDD) mit dem Diglycidylether von Bisphenol A (DGEBA) wurde mittels isothermer und dynamischer Differentialkalorimetrie untersucht. Die Enthalpie der Reaktion einer Epoxygruppe mit einem Amin-Wasserstoff wurde zu 112 ± 5 kJ/mol bestimmt.Die Gültigkeit eines kinetischen Modells wurde bestätigt. Es beinhaltet zwei konkurrierende Mechanismen: zum einen die Katalyse durch Hydroxy-Gruppen, die entweder an die Epoxykette gebunden sind oder während der Reaktion gebildet werden (Aktivierungsenergie 77 ± 5 kJ/mol), zum anderen eine nicht katalysierte Reaktion mit einer höheren Aktivierungsenergie (103 ± 3 kJ/mol).Eine Gelierung beeinflußt die Kinetik der isothermen Härtung nicht. Aus den Gelzeiten wurde die Bruttoaktivierungsenergie ermittelt (62 ± 2 kJ/mol).
    Notes: The reaction between the diglycidylether of bisphenol A (DGEBA) and 4,9-dioxa-1,12-dodecanediamine (DDDD) has been studied by means of isothermal and dynamic differential scanning calorimetry. The enthalpy of the reaction of an epoxy group with an amino-hydrogen has been determined to be 112 ± 5 kJ/mol. A kinetic model has been validated. It involves two competitive mechanisms: one is catalysed by the hydroxy groups initially present on the epoxy chain or generated during the reaction (activation energy 77 ± 5 kJ/mol), the other is not catalysed with a higher activation energy (103 ± 3 kJ/mol).For each isothermal curing, the kinetics are not modified by gelation. Evaluated from the gel times, the overall activation energy of the reaction is equal to 62 ± 2 kJ/mol.
    Additional Material: 8 Ill.
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    New flame-retardant poly(pyromellitic imide aryl phosphoramide-ester)s (1993)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 206 (1993), S. 63-68 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Durch Grenzflächen-Polykondensation von N,N′-bis(4-hydroxyphenyl)pyromellitsäurediimid mit Dichloriden verschiedener Phosphoramide wurden flammhemmende Polymere erhalten. Diese wurden mittels IR- und 1H-NMR-Spektroskopie und Elementaranalyse charakterisiert. Thermische Stabilität und Entflammbarkeit wurden thermogravimetrisch bzw. durch Bestimmung des Sauerstoff-Indexes untersucht.
    Notes: Flame-retardant poly(pyromellitic imide aryl phosphoramide-ester)s were synthesized by interfacial polycondensation of N,N′-bis(p-hydroxyphenyl)pyromellitic diimide with aryl phosphoramidic dichlorides. The polymers were characterized by IR and 1H-NMR spectroscopy. The molecular composition was confirmed by elemental analysis. The thermal stability and flammability of the polymers were studied by thermogravimetry and limiting oxygen index, respectively.
    Additional Material: 3 Ill.
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    URL: http://dx.doi.org/10.1002/apmc.1993.052060106
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    Studies on simultaneous curing of nadimides and allyl nadic-imidesNadic imide: Bicyclo[2.2.1]hept-5-ene-2,3-dicarboximide. and thermal behaviour of cured resinsPaper presented at VIIIth National Symposium and Workshop on Thermal Analysis held at Bhubaneshwar on December 19-21, 1991. (1993)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 206 (1993), S. 53-62 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Der Einfluß von Zusammensetzung und chemischer Struktur auf die thermischen Eigenschaften von Polyimiden aus handelsüblichen Allyl-„Nadimid“-Harzen und Phosphor enthaltenden “Nadimid”-Harzen wurde untersucht. Thermogravimetrische Messungen unter Stickstoff an Harzen, die 1 h bei 300 gehärtet wurden, ergaben eine Erhöhung der thermischen Stabilität.
    Notes: The effect of composition and chemical structure of addition polyimides on thermal characteristics was investigated using commercially available allyl nadic-imide resins and phosphorus-containing nadimide resins. Thermogravimetric analysis, in N2 atmosphere, of resins cured at 300°C for 1 h revealed improvement of thermal stability.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1993.052060105
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    Graft copolymers having hydrophobic backbone and hydrophilic branches, 8For Part 6, cf.7, for Part 7, cf.6.. Effect of temperature on the dispersion copolymerization of poly(ethylene glycol) macromonomer with styrene (1993)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 206 (1993), S. 69-75 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Polyethylenglykol-Makromonomere mit Methacryloyl-Endgruppen wurden in Gegenwart von 2,2′-Azo(N,N′-dimethylenisobutyramidin) in einem Ethanol/Wasser-Gemisch (4:1, v/v) bei verschiedenen Temperaturen mit Styrol copolymerisiert. Die Gesamtaktivierungsenergie dieser Dispersionscopolymerisation beträgt 48 kJ/mol.
    Notes: Copolymerization of poly(ethylene glycol) macromonomers with terminal meth-acryloyl groups with styrene was carried out in the presence of 2,2′-azobis(N,N′-dimethyleneisobutyramidine) in ethanol/water mixture (4:1, v/v) at various temperatures. The overall activation energy for the dispersion copolymerization was obtained as 48 kJ/mol.
    Additional Material: 3 Ill.
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    URL: http://dx.doi.org/10.1002/apmc.1993.052060107
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    Magnetic bead cellulose (1993)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 212 (1993), S. 147-155 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Magnetische Zellulosepartikel wurden aus Viskose und Eisenpulver mit einer den thermischen Sol-Gel-Übergang nutzenden Suspensionsmethode hergestellt. Die so erhaltenen Teilchen konnen mit einem von außen angelegten, rotierenden Magnetfeld eines üblichen Permanentmagneten durchmischt werden. Die Abtrennung der Partikel von der Reaktionssuspension sollte in einer dünnen Schicht des Materials durch ein starkes Magnetfeld erfolgen. Magnetische Zellulosepartikel, die mit einer SmCoFe-Legierung anstelle des Ferrits hergestellt wurden, besitzen bessere magnetische Eigenschaften.
    Notes: Mangetic bead cellulose was prepared from viscose and ferrite powder by employing the suspension procedure using the thermal sol-gel transition. The particles thus obtained can be stirred if acted upon by an external rotary magnetic field of a common permanent magnet. Isolation of the particles from reaction suspensions should proceed in a thin layer using a strong magnetic field. Magnetic bead cellulose prepared from supermagnetic powder of the SmCoFe alloy shows a better behaviour in the magnetic field than ferrite materials.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1993.052120113
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    Methodological investigations on the thermal stability of polypropylene (1993)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 212 (1993), S. 103-119 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Unterschiedliche Methoden zur Messung der thermo-oxidativen Stabilität von Polypropylen wurden verglichen. Die Induktionszeiten des oxidativen Abbaus wurden mittels Differentialkalorimetrie (DSC) zwischen 160 und 240°C bis zu 10000 min gemessen. Die gleichen Proben wurden bei 130 bis 160°C 13000 h einer Alterung im Heizofen ausgesetzt.Unterschiedlich stabilisierte Proben ergaben bei dynamischen DSC-Messungen unterschiedliche Ergebnisse. Die Übereinstimmung zwischen dynamischen und statischen Experimenten waren bei kleinen Heizraten am besten.Die Arrhenius-Diagramme der isothermen DSC-Messungen unterscheiden sich von denen der Alterungsversuche; die erhaltenen Geraden schneiden sich entweder in der Nähe der Polypropylen-Schmelzpunkte oder verschieben sich bei den durch Temperung gealterten Proben zu längeren Zeiten. Die scheinbaren Aktivierungsenergien aus den Ofen-Temperungsmessungen sind sehr vie1 niedriger als die aus den DSC-Messungen berechneten und liegen bei allen Proben in einem einheitlichen Bereich, während bei den DSC-Experimenten ein Einfluß des Stabilisators zu erkennen ist.Die thermische Stabilität von Polypropylen wird auch von Antistatika und Farbpigmenten beeinflufßt. Besonders Rot-Pigment wirkt als Stabilisator für Polypropylen, was aus den Ofen-Alterungsversuchen hervorgeht; es verliert diesen Effekt aber bei höheren Temperaturen.
    Notes: The correlation between different methods of measuring thermo-oxidative stability of polypropylene has been studied. The oxidation induction times were measured using differential scanning calorimetry (DSC) in the temperature range from 160°C to 240°C up to 10000 min. The same samples were oven-aged in the temperature range from 130°C to 160°C up to 13000 h.The dynamic experiments performed by DSC show different results for differently stabilized samples. At slow heating rates the results of the dynamic experiments corresponded best to the results of the isothermal experiments.The straight-line Arrhenius plots of the isothermal DSC measurements do not correlate with the straight-line Arrhenius plots of the oven-aging tests. The Arrhenius plots obtained by these two methods either intersect close to the melting temperature of polypropylene or show jumps towards longer times when switching from DSC to oven-aging. It was found that the apparent activation energies obtained from the oven-aging tests are much lower than these obtained by DSC measurements. Almost the same activation energies were obtained for all the samples in oven-aging, while for the differently stabilized samples the activation energies from DSC measurements showed different results.Antistatic additives and colour pigments influence the thermal stability of polypropylene. Especially red pigment acts like a stabilizer for polypropylene, which is noticed at oven-aging testing, but at higher temperatures it loses this stabilizing effect.
    Additional Material: 6 Ill.
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    URL: http://dx.doi.org/10.1002/apmc.1993.052120110
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    Announcement (1993)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 212 (1993), S. 201-202 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1993.052120118
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    Removal of escherichia coli from water by systems based on polystyrene-g- and poly(glycidyl methacrylate)-g-amines (1993)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 207 (1993), S. 31-41 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Aktiviertes Aluminiumoxid wurde mit den Produkten der Reaktionen von chlormethyliertem Polystyrol mit Diethylamin, von Poly(styro1-co-chlormethylstyrol) mit Diethanolamin und von Poly(styro1-co-glycidylmethacrylat) mit Diethanolamin belegt und zur Adsorption von Escherichia-coli-Bakterien aus Wasser eingesetzt. 100 mg belegtes Trägermaterial wurden mit einer E.-coli-Suspension (20 ml, 107-8 Zellen/ml) gerührt, wobei die Zahl der lebensfähigen Zellen durch Adsorption abnahm; das Adsorptionsgleichgewicht wurde nach etwa 2 h erreicht. Der Abnahme-Koeffizient D (entspricht der Adsorptionsgeschwindigkeitskonstante) wurde aus der Abnahme der Zahl der lebensfähigen Zellen nach 2 h Adsorption gemessen.
    Notes: Reaction products of soluble chloromethylated polystyrene with diethylamine, poly(styrene-co-chloromethylstyrene) with diethanolamine, and poly(styrene-co-glycidyl methacrylate) with diethanolamine were prepared and supported on activated alumina granules. A study was made of removal of Escherichia coli cells from water by these supported alumina granules. When these granules (0.100 g) were stirred in a viable cell suspension (107-8 cells/ml, 20 ml), the viable cell number decreased by the adsorption of the cells to the granules. The adsorption attained approximately to the equilibrium (saturated adsorption) after about 2 h from the start of the adsorption. The decrease coefficient (D, which corresponds to the adsorption rate constant) was determined from the decrease in the viable cell number in the adsorption for about 2 h from the start.
    Additional Material: 3 Ill.
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    URL: http://dx.doi.org/10.1002/apmc.1993.052070104
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    Radical polymerization of mono- and di-methacrylic esters containing bisphenol-S (1993)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 207 (1993), S. 43-52 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Die radikalische Polymerisation von Bisphenol-S enthaltenden Mono- und Dimethacrylsaureestern (BPS-M und BPS-DM) wurde bezüglich Polymerisationsgeschwindigkeit, Läsungsmitteleinfluß, Copolymerisation und Kinetik der Photovernetzung untersucht. Es zeigte sich, daß das Lösungsmittel die Polymerisationsgeschwindigkeit signifikant beeinflußt; polare Lösungsmittel wie DMSO und Acetonitril verlangsamen die Polymerisationsgeschwindigkeit. Die Copolymerisation von BPS-M (M1) mit MMA (M1) wurde in Aceton bei 60°C untersucht. Die Copolymerisationsparameter wurden nach der Fineman-Ross-Methode zu r1 = 3,72 ± 0,0l und r2 = 0,80 ± 0,0l berechnet. Die hohe Reaktivität von BPS-M in diesem Copolymerisationssystem kann vermutlich dem „Matrix-Effekt“ zugeschrieben werden. Funktionelle Polymere mit Methacrylat- Seitengruppen wurden erfolgreich modifiziert und durch Bestrahlung in Gegenwart von Benzoinisopropylether photovernetzt. Die Kinetik der Photovernetzung ist zweiter Ordnung.
    Notes: Radical polymerizations of mono- and di-methacrylic esters containing bisphenol-S (BPS-M and BPS-DM) were studied in terms of polymerization rate, solvent effect, copolymerization and kinetic measurements of photocrosslinking. The solvents were found to affect significantly the polymerization rate. Polar solvents such as DMSO and acetonitrile were found to slow down the polymerization rate. Copolymerization of BPS-M(M1) with MMA(M2) was studied in acetone at 60°C. The monomer reactivity ratios were calculated to be r1 = 3.72 ± 0.01 and r2 = 0.80 ± 0.01 by the Fineman-Ross method. The high reactivity of BPS-M observed in this copolymerization system may be due to the “matrix effect”. Functional polymers containing methacrylate side-groups were successfully modified and photocrosslinked by irradiation in the presence of benzoin isopropyl ether. The photocrosslinking process is found to be of second order kinetics.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1993.052070105
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    Supported titanium catalyst for propylene polymerization. Convenient synthesis of unsolvated anhydrous magnesium chloride from MgCl2 · 6 H2OIPCL Communication No. 220. (1993)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 207 (1993), S. 53-63 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Die Reaktion von Chlorsilanen (Me3SiCl, R2SiCl2, SiCl4; R=Me, Ph) mit MgCl2 · 6 H2O wurde bezüglich der Entfernung des Kristallwassers untersucht. Die Dehydratisierungsgeschwindigkeit hängt von der Art des Chlorsilans ab. Bei der Reaktion mit Dichlordiphenylsilan entsteht in hoher Ausbeute ungelöstes, wasserfreies Magnesiumchlorid, das als Trägermaterial für die Herstellung eines Titan-Katalysators verwendet wurde. Dieser zeigt mit Et3Al und Ph2Si(OMe), als Cokatalysatoren eine hohe Aktivität für die Propylenpolymerisation.
    Notes: Reaction of chlorosilanes (Me3SiCl, R2SiCl2, SiCl4; R=Me, Ph) with MgCl2 · 6 H2O were investigated for the efficiency of removal of water. The nature of chlorosilane is found to govern the rate of dehydration. The treatment of hydrated magnesium chloride with dichlorodiphenylsilane gives unsolvated anhydrous magnesium chloride in high yields. Anhydrous MgCl2 is used as support for the preparation of titanium catalyst. The catalyst in conjunction with Et3Al and Ph2Si(OMe)2 as cocatalyst system shows high activity for propylene polymerization.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1993.052070106
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    Syntheses and reactions of photopolymers, I. New photosensitive azo monomers, photolysis, interfacial polycondensation, viscosity measurements, photodegradation (1993)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 207 (1993), S. 65-79 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Es wird die Synthese verschiedener, mindestens bifunktioneller Azoverbindungen und deren Einbau in eine Polymerhauptkette mittels Grenzflächenpolykondensation beschrieben. Die thermischen und photochemischen Eigenschaften von Modellverbindungen sowie der Polymeren wurden durch UV-Spektroskopie und DSC-Messungen untersucht. Mit Hilfe von Viskositätsmessungen wurde der Kettenabbau eines Azopolymeren nachgewiesen.
    Notes: The synthesis of new, unsymmetrically functionalized azo compounds and their incorporation into polymers is described. Their photochemical decomposition and thermal stability was studied by UV spectroscopy and differential scanning calorimetry (DSC), respectively. Chemical degradation was followed by viscosity measurements.
    Additional Material: 5 Ill.
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    URL: http://dx.doi.org/10.1002/apmc.1993.052070107
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    Linear polythioesters, XXIII. Products of interfacial polycondensation of 4,4′-dimercaptobiphenyl with acid dichlorides (1993)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 207 (1993), S. 173-186 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Durch Phasengrenzflächenpolykondensation von 4,4′-Dimercaptobiphenyl mit ausgewählten aliphatischen und isomeren Phthalsäuredichloriden wurden neue Polythioester erhalten. Um die optimalen Bedingungen der Phasengrenzflachenpolykondensation zu bestimmen, wurde der Einfluß folgender Faktoren auf die reduzierte Viskosität und Ausbeute der Polythioester ermittelt: Art der organischen Phase, Konzentration der Reagenzien, Verhältnis der wässrigen zur organischen Phase, Art und Konzentration des HC1-Akzeptors, Reaktionstemperatur und -zeit. Die Polykondensation von Dithiol mit Isophthalsäuredichlorid wurde als Modellsystem speziell untersucht. Die Polythioesterstrukturen wurden mittels Elementaranalyse, IR-Spektroskopie und Riöntgenspektroskopie bestimmt. Aus der thermogravimetrischen Analyse wurden die Anfangszersetzungstemperatur, die Gewichtsabnahme bei dieser Temperatur und das Maximum der Zersetzungsgeschwindigkeit erhalten. Es wurden weiterhin einige physikalisch-chemische, mechanische und dielektrische Eigenschaften ermittelt. Aufgrund der geringen Löjslichkeit der Polythioester konnten die mittleren Molekulargewichte nicht bestimmt werden.
    Notes: New polythioesters were obtained by interfacial polycondensation of 4,4′-dimercaptobiphenyl with selected aliphatic and isomeric phthaloyl dichlorides.To determine the optimum polycondensation conditions, the influence of the following factors on reduced viscosity and yield were studied: type of organic phase, concentration of hydrogen chloride acceptor, type of catalyst, reaction temperature and rate of acid dichloride addition.A thorough examination was carried out only for the polycondensation of dithiol with isophthaloyl dichloride chosen as a model system. The structures of polythioesters were determined by elemental analysis, X-ray and infrared spectra. The temperature of initial decomposition, the percentage of its mass loss, and temperature of the fastest decomposition process were determined from curves of differential and thermogravimetric analysis.Some physicochemical, mechanical and electrical properties were determined. The molecular weights were not measured because of the low solubility of the obtained polythioesters.
    Additional Material: 6 Ill.
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    URL: http://dx.doi.org/10.1002/apmc.1993.052070116
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    Announcements (1993)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 207 (1993), S. 215-216 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1993.052070120
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    Cationic surface modification by polyelectrolytes: Polyelectrolyte complex formation at inorganic particle surfaces (1993)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 207 (1993), S. 203-213 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Die negativ geladene Oberfläche von feindispersen anorganischen Materialien wie Kieselgur, Perlit, Kaolin oder Glas kann durch die Adsorption von kationischen Polyelektrolyten umgeladen werden. Bei hohen Mengen an adsorbiertem Polykation besitzen die Oberflächen der unterschiedlichen Materialien dann gleiche elektrokinetische Eigenschaften. An den derart modifizierten Grenzflächen können anionische Farbstoffe adsorbiert werden. Bei Zugabe eines Polyanions, resultierend in der Bildung eines Polyelektrolytkomplexes, kann die Zahl der kationischen Zentren in der Grenzfläche und damit die Adsorptionskapazität für den Farbstoff erhöht werden. Die experimentellen Resultate deuten darauf hin, daß das Zetapotential bestimmt wird durch die außeren Bereiche der PEC-Schicht, wahrend die Farbstoffadsorption auch durch die inneren Regionen der Oberfläche mitbestimmt wird. Unmittelbar nach der Modifizierung mit Poly(diallyldimethylammoniumchlorid) und Poly(maeinsäure-co-α-methylstyrol) besitzen die modifizierten Materialien bei einem hohen Überschuß des Poly-anions ein negatives Zetapotential, aber ein positives nach der Abtrennung der überstehenden Lösung. Dieses Verhalten steht in Übereinstimmung mit der Bildung eines nichtstochiometrischen PEC mit Polykation im Überschuß und einer reversiblen Wechselwirkung mit überschüssigem Polyanion in der Lüsung. Die Ergebnisse deuten an, daß die Oberflache als fest-analoger Polyelektrolyt in Konkurrenz zu dem Polyanion an der Reaktion beteiligt ist.
    Notes: The surface charge of inorganic finely dispersed materials like diatom earth, perlite, glass or clay may be changed from negative to positive by the adsorption of cationic polyelectrolytes. Different materials exhibit equivalent electrokinetic surface properties with high amounts of the polycation adsorbed. Interfaces modified this way are able to adsorb anionic dye stuffs. Their adsorption capability for the dye stuff may be enhanced by addition of polyanions due to the formation of a nonstoichiometric polyelectrolyte complex (PEC) and therefore an increased number of cationic centres in the interface. Experimental results indicate that the zeta potential is correlated to the outer PEC layer whereby dye stuff adsorption measurements are sensitive for the more inner surface regions, too. Immediately after modification, materials modified with poly(diallyldimethylammonium chloride) and poly(maleic acid-co-α-methylstyrene) have negative zeta potentials at high excess of added polyanion and a positive one after separation of the solid. This behaviour is attributed to the formation of a nonstoichiometric PEC with polycation in excess and reversible interaction with polyanion in the surrounding solution. Experimental results indicate that the surface may act as “solid-like” polyelectrolyte in competition to the polyanion.
    Additional Material: 6 Ill.
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    URL: http://dx.doi.org/10.1002/apmc.1993.052070119
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    Sulfobetaine polyurethane ionomers, 2. Dielectric relaxation in polyether-based polymer and related compounds with Co2+ (1993)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 207 (1993), S. 195-202 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Die dielektrischen Relaxationsprozesse in Sulfobetain-Polyurethanionomeren mit Polyethersegmenten (Co2+ -komplexierte und H,S-behandelte Formen) wurden mit der TSDC-Methode untersucht und mit denen nichtionischer Polyurethane und verwandter Verbindungen verglichen. Vier mit c, βs, β′ und βh bezeichnete Relaxationsprozesse wurden in Polyurethanionomeren im Temperaturbereich von 110 bis 370 K beobachtet und mit möglichen molekularen Bewegungsprozessen korreliert. Die Einflüsse des Gehalts an Hartsegmenten, der Komplexierung sowie der H2S-Behandlung auf die Relaxationsprozesse wurden unter Berücksichtigung der strukturellen Modifikationen der harten und der weichen Mikrophasen erklärt.
    Notes: Dielectric relaxation processes in sulfobetaine polyurethane ionomers based on polyether, were studied comparatively to nonionic polyurethane and related compounds with Co2+ (complexed and H2S-treated forms) by using thermally stimulated depolarization currents (TSDC).Four relaxation processes denoted as γ, βs, β′ and βh in polyurethane ionomers over the 110-370 K range were observed. Molecular origin of these processes was suggested. The effects of the hard segments content, complexation and H2S treatment on the relaxation processes were explained in terms of the structural modifications of the hard and soft microphases.
    Additional Material: 5 Ill.
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    URL: http://dx.doi.org/10.1002/apmc.1993.052070118
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    Metal ion complexation of poly(acrylamide)-supported amines crosslinked with N,N′-methylene-bis-acrylamideSystematic name: N-(acrylamidomethyl)acrylamide. (1993)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 208 (1993), S. 1-15 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Die Komplexierung von Co(II), Ni(II), Cu(II), Zn(II) und Hg(II) in Amin-funktionalisierten, mit N-(Acrylamidomethyl)acrylamid (NNMBA) vernetzten Polyacrylamiden wurde untersucht. Die Metallionenaufnahme hängt vom Vernetzungsgrad ab und nimmt in der Reihenfolge Hg(II) ≫ Cu(II) 〉 Zn(II) 〉 Ni(II) 〉 Co(II) ab. Die Kinetik der Komplexierung ist erster Ordnung. Die Metallkomplexe wurden mittels IR- und EPR-Spektroskopie charakterisiert. Die Harze können ohne Kapazitätsverlust nach Dekomplexierung mehrmals verwendet werden; die desorbierten Harze komplexieren bevorzugt das vorher gebundene Metallion. Das Quellvermögen der komplexierten ist geringer als das der nichtkomplexierten Harze und hängt vom Vernetzungsgrad ab.
    Notes: The complexation of amino functions supported on poly(acrylamides) with 2-20 mol-% of N-(acrylamidomethyl)acrylamide (NNMBA) crosslinks towards Co(II), Ni(II), Cu(II), Zn(II), and Hg(II) ions was investigated. The metal ion uptake was found to be dependent on the extent of the NNMBA crosslinking. The observed trend in complexation is Hg(II) ≫ Cu(II) 〉 Zn(II) 〉 Ni(II) 〉 Co(II). The kinetics of complexation was found to be of first order. The derived metal complexes were characterised by IR and EPR. The complexed resins can be recycled several times without capacity loss. The metal-desorbed resins showed specificity to the metal ion which was initially present. The extent of swelling of the complexed resins is lower than that of the uncomplexed resins and it varies with the extent of crosslinking.
    Additional Material: 8 Ill.
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    URL: http://dx.doi.org/10.1002/apmc.1993.052080101
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    Conduction mechanism of polycarbonate doped with different transition metals (1993)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 208 (1993), S. 17-23 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Die elektrische Leitung von mit verschiedenen Übergangsmetallen (Fe, Co, Cu, Cr) dotiertem Polycarbonat (PC) wurde im Temperaturbereich von 293 bis 493 K untersucht. Die Leitfähigkeit von PC mit FeCl, war siebenmal höher als jene der anderen Proben. Die effektive Potentialschwelle Φ wurde zu 0,2 eV berechnet. Weiterhin wurde die Dielektrizitätskonstante bei verschiedenen Temperaturen untersucht.
    Notes: The electrical conduction of polycarbonate (PC) doped with different transition metals was studied in the temperature range of 293-493 K. The conductivity of PC doped with FeCl3 is 7 orders higher in comparison with the other samples. The effective potential barrier (Φ) for pure PC was calculated (0.2 eV). Also, the dielectric constant at different temperatures was studied.
    Additional Material: 4 Ill.
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    URL: http://dx.doi.org/10.1002/apmc.1993.052080102
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    Photooxidative ageing of low density polyethylene. Kinetics determined by an electrical method (1993)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 208 (1993), S. 25-38 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Die Wirkung von Lichtstabilisatoren im ersten Stadium der Alterung von Polyethylen niedriger Dichte (LDPE) wurde mit elektrischen Methoden untersucht. Drei verschiedene UV-Stabilisatoren wurden verwendet: ein Phosphit-Derivat (3,9-Bis[(2,4-di-tert-butyl)phenoxy]-2,4,8,l0-tetraoxa-3,9-diphosphaspiro[5.5]undecane), ein Benzophenon-Derivat (2-Hydroxy-4-octyloxybenzophenon) und ein Chelat [2,2′-Thiobis(4-tert-octylphenolato)(n-butylamino)nickel(II)]. Diese Stabilisatoren, speziell das Chelat, verbesserten die UV-Stabilität von LDPE für elektrische Anwendungen.
    Notes: The efficiency of light stabilizers is investigated by electric methods in the initial stage of photooxidative ageing of low density polyethylene (LDPE). Three types of UV light stabilizers are tried to improve the UV stability of LDPE: a phosphite type (3,9-bis-[(2,4-di-tert-butyl)phenoxy]-2,4,8,10-tetraoxa-3,9-diphosphaspiro[5.5]undecane) a benzophenone type [2-hydroxy-4-octyloxy-benzophenone] and a stabilizer based on chelate salt [2,2′-thiobis(4-tert-octyl phenolato) (n-butylamine) nickel (II)]. LDPE is very susceptible to ultraviolet light. UV light stabilizers improve the stability of low density polyethylene for electrical applications, especially the UV stabilizer based on chelate salt.
    Additional Material: 7 Ill.
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    URL: http://dx.doi.org/10.1002/apmc.1993.052080103
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    Volume change by solvent and temperature of poly(vinyl alcohol) crosslinked by electron irradiation (1993)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 208 (1993), S. 39-46 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Ein Poly(vinylalkohol)-Film (PVA) wurde nach Erhitzen in siedendem Wasser gequollen und durch Bestrahlen mit Elektronen vernetzt. Das so erhaltene PVA-Hydrogel weist eine höhere Elastizität und bessere mechanische Eigenschaften auf, obwohl es noch quellbar ist. Das Volumen des vernetzten Hydrogels reagiert sehr empfindlich auf einen Wechsel des Quellungsmittels und eine Temperaturänderung. Nach Kontraktion durch Eintauchen in Aceton nimmt die Zugfestigkeit zu. Durch wiederholtes Erhitzen des Hydrogels in siedendem Wasser und anschließendes Abkühlen wurden Kontraktions-Quellungs-Zyklen durchlaufen. Bei Temperaturen oberhalb 40°C nimmt das Quellungsverhältnis stark ab.
    Notes: Responsive poly(vinyl alcohol) PVA hydrogels obtained by electron irradiation after heating of a water-swollen film show higher elasticity and tougher properties even after boiling in water, although some swelling did occur. The volume of the hydrogel after boiling was very sensitive to solvent (acetone) and temperature. The crosslinked hydrogels show higher tensile strength after rapid contraction by immersion in acetone. The crosslinked PVA was boiled and cooled to induce contraction and swelling cycles. The swelling ratio of hydrogel decreased remarkably at temperatures higher than 40°C.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1993.052080104
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    The interfacial polycondensation of tetrabromobisphenol-A polycarbonate. I. Model reaction and mechanism studies (1993)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 208 (1993), S. 65-77 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Die Umsetzung von 2,2′,6,6′-Tetrabrombisphenol A (TBBPA) mit Phosgen in einer mit Trialkylamin katalysierten Grenzflächenpolykondensation liefert nur Polymere mit niedrigem Molekulargewicht. Die geringe Reaktivität von TBBPA wird auf dessen sterisch anspruchsvolle Struktur und den elektronenziehenden Charakter der o-Bromsubstituenten zurückgeführt. Aus der Bildung von Carbamaten bei der Reaktion einer Modellverbindung (2,4,6-Tribromophenylchlorformat, TBPC) mit Trialkylaminen geht hervor, daß durch Zerfall des Katalysator-TBPC-Komplexes die Polymerisation abgebrochen wird. Das Carbamat wird durch Zersetzung des Acylammoniumsalzes gebildet, wobei eine nucleophile Substitution durch das Chloridion an dem an das positiv geladene Stickstoffatom gebundenen Kohlenstoffatom stattfindet.
    Notes: 2,2′,6,6′-Tetrabromobisphenol-A (TBBPA), a sterically hindered bisphenol, is known to give only low-molecular-weight polymers using the interfacial phosgenation process. The low reactivity is attributed to the bulkiness and electron-withdrawing character of bromine substituents at the ortho positions. From the formation of carbamate products in model compound (2,4,6-tribromophenyl chloroformate, TBPC) reactions with trialkylamines, the trialkylamine catalyst was found to act as a terminator by the degradation of the chloroformate-trialkylamine complex. The generation of carbamate occurs through the decomposition of the acyl ammonium salt proceeding via nucleophilic displacement by Cl- at the carbon attached to the positive nitrogen center. The relative catalytic abilities of trialkylamines and pyridine derivatives were determined in the homogeneous (dichloromethane) and interfacial (dichloromethane/water) systems. From the results of model reactions with TBPC and sodium tribromophenolate, 4-dimethylaminopyridine (DMAP) was found to be the best catalyst.
    Additional Material: 7 Ill.
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    URL: http://dx.doi.org/10.1002/apmc.1993.052080106
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    Change of mechanical properties of crosslinked polyethylene during its thermo-oxidative aging (1993)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 208 (1993), S. 47-64 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Die thermische Alterung von extrudierten Proben von mit Elektronenstrahlen vernetztem linearem Polyethylen wurde im Temperaturbereich von 110-170°C untersucht. Kurz- und langfristige Veränderungen der mechanischen (Dehnungs-)Eigenschaften wurden beobachtet; die entsprechenden Alterungsmechanismen werden auf der Basis ergänzender Sol-Gel-, Dichte-, FTIR- sowie gravimetrischer Messungen und Zugversuche an Mikrotomschnitten diskutiert.Zwei Mechanismen führen zu kurzfristigen Eigenschaftsänderungen: eine Nachvernetzung und eine Änderung der Kristallstruktur (bei Proben oberhalb ihrer Schmelztemperatur). Im vorliegenden Fall wurden die Polymeren im festen Zustand vernetzt, so daß die Änderung der Kristallstruktur zu einer erkennbaren Abnahme der Streckspannung (ca. 5 MPa) führte.Die langfristigen Veränderungen treten nach dem Ende der Oxidationsinduktionsperiode auf. Sie können als Übergang vom zähen in den spröden Zustand interpretiert werden, der durch Strukturänderungen sowohl auf molekularer (durch Kettenspaltung) als auch makroskopischer Ebene (durch diffusionskontrollierte Kinetik der Oxidation verursachte Kern-Schale-Struktur) hervorgerufen wird. Durch IR- und DSC-Analysen wurde festgestellt, daß wahrnehmbare Änderungen in der Dehnung erst kurz vor dem Ende der Induktionsperiode auftreten.
    Notes: The thermal aging of extruded samples of electron beam-crosslinked linear polyethylene has been studied in the 110-170°C temperature range. Short and long term changes of mechanical (tensile) properties were observed, and the corresponding mechanisms are discussed on the basis of complementary sol-gel and gravimetric measurements on whole samples, and density, FTIR and tensile testing on microtome sections.Two mechanisms are involved in short term changes: a post-crosslinking and a change of the crystalline morphology (for samples exposed above the melting point). The latter effect is especially important in the case under study where the polymer was crosslinked in the solid state and leads to a noticeable decrease (∼5 MPa) of the yield stress.The long term changes take place after the end of the induction period of oxidation. They can be interpreted in terms of ductile-brittle transition induced by structural changes occurring on the macromolecular level (chain scission) as well as macroscopically (core-shell structure resulting of the diffusion control of oxidation kinetics). It appears that noticeable changes of ultimate elongation occur just before the end of the induction period as detected by IR or DSC method.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1993.052080105
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    Chemical modification of poly(epichlorohydrin) with unsaturated potassium carboxylates (1993)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 209 (1993), S. 95-109 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Poly(epichlorhydrin) wurde durch nukleophile Substitution mit aliphatischen Kaliumcarboxylaten mit endstandigen Doppelbindungen (10-Undecenoat, 4-Pentenoat und 3-Butenoat) modifiziert. Die Reaktionsbedingungen wurden variiert, um ihren Einfluß auf den erreichten Substitutionsgrad zu untersuchen. Die hergestellten Polyether wurden mittels Elementaranalyse, spektroskopischen und thermischen Methoden sowie Viskositäts- und osmometrischen Messungen charakterisiert. Es wurde sowohl eine geringe Vernetzung als auch die bereits bekannte Hauptkettenspaltung beobachtet. Während der Substitutionsreaktion isomerisierte das Vinylacetat zum Crotonsäureester.
    Notes: Poly(epichlorohydrin) was modified by nucleophilic substitution with some aliphatic potassium carboxylates containing terminal double bonds (10-undecenoate, 4-pentenoate and 3-butenoate). In order to monitor the degree of substitution achieved, different reaction conditions were tested. The polyethers obtained were characterized by spectroscopic techniques, elemental analysis, thermal methods, viscosity determinations and osmometric measurements. A slight crosslinking and the reported main chain cleavage were both detected. Finally, it must be pointed out that, during the substitution reaction with the vinylacetate, isomerization to crotonic ester took place.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1993.052090109
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    Surface modification of a polypropylene film by low-pressure discharge and the adhesion of a vacuum-deposited layer of aluminium (1993)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 210 (1993), S. 21-32 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Polypropylen wurde mittels Gasentladung unter niedrigem Druck behandelt. Die Oberflaäachenmodifizierung wurde durch ESCA-Analysen, Messungen der Benetzbarkeit und Adhäasionsunterschungen in Abhäangigkeit von der Behandlungszeit und der Art des verwendeten Gases (Luft oder Argon) charakterisiert. Die Ergebnisse von “advancing”- und “receding” -Kontaktwinkelmessungen mit Wasser (sehr polar) und Diiodmethan (unpoler) in einem automatischen dynamischen Tensiometer ziegen eine Zunahme der Benetzbarkeit nach der Oberfläachenbehandlung. Dier wird auf die entstehung hochenergetisch polarer Stellen auf der Oberfläache zuräuckgefäuhrt. Die ESCA-Analyse belegt, daß die modifizierte Oberfläahe aud niedermolekularem Material besteht; sie ist in Methanol läolich.Die Adhäsion von Aluminium an der Polypropylen-Oberfläche wird bereits durch eine wenige Sekunden dauernde Gasentladungsbehandlung verbessert. Sie hängt von der polaren Komponente der Oberflächenenergie des Polymeren ab.
    Notes: Low-pressure discharge treatments were applied to the surface of polypropylene. ESCA analyses, wettability measurements and adhesion tests were carried out to characterize surface modifications as a function of treatment time and nature of gas (air or argon). Advancing and receding contact angles were measured with an automatic dynamical tensiometer. The liquids used were water (very polar liquid) and methylene iodide (apolar liquid). The results show an increase in wettability by the surface treatment. This is due to the creation of high-energy polar sites. ESCA analysis also shows that the modified surface layer is soluble in methanol and is made up of low-molecular-weight material.Adhesion of polypropylene/aluminium is also increased by the low pressure discharge treatment from the few first seconds of the treatment. This adhesion increase is a function of the polar component of the polymer surface energy.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1993.052100103
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    Poly-ε-caprolactone/poly(Methylmethacrylate) reactive blends: Correlation between synthesis, morphology and physical properties (1993)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 210 (1993), S. 47-59 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Blends aus Poly-ε-caprolacton (PCL) und Polymethylmethacrylat (PMMA) wurden durch Polymerisation von Methylmethacrylat in Gegenwart von PCL hergestellt. Die thermeischen, morphologischen, dynamisch-mechanischen und mechanischen Eigenschaften der Blends wurden ermittelt. Zum Vergleich wurden Blends durch mechanisches Mischen von PCL-und PMMA-Homopolymerschmelzen hergestellt und charakterisiert. Die nach beidenMethoden hergestellten Blends unterscheiden sich wesentlich in der phasenstrukturund den mechanischen eigenschafte, was wahrscheinlich auf die bildung von gepfropften Anteilen bei der erstgenannten Methode zuräuckgefäuhrt werden kann.
    Notes: Blends of poly-ε-caprolactone (PCL) and poly(methylmethacrylate) (PMMA) were prepared by a reactive method and characterized by thermal, morphological, dynamic mechanical and mechanical analyses. For comparison, “mechanical” blends, obtained by melt-mixing of preformed polymers, have been prepared and characterized. The two series of blends are different in phase structure and in mechanical tensile properties, probably due to the formation of grafted species during reactive blending.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1993.052100105
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    Composites of surface-treated wood fiber and recycled polypropylene (1993)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 210 (1993), S. 33-46 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Der Einfluß der Oberfläachenbehandlung von Säagemehl auf die physikalisch mechanischen Eigenschaften von mit Säagemehl gefäulltem Polypropylen wurde untersucht. Wäahrend mit Elastomerem beschichtetes Säagemehl die Festigkeit der Compostie veschlechtert, fäuhrt diein-situ-Addition von Oberfläachenmodifikatoren (mit Maleinsäaureanhydrid oder N-(3-Maleimidophenyl) maleimid modifiziertes Polypropylen) wäahrend des Knetens des Polypropylens mit unbehandeltem odermit Elastomerem vorbehandeltem Säagemehl zu einer Verbesserung der mechanischen Eigenschaften bei nurgeringer Beeinträachtigung der Schlagzäahigkeit. Die chemische Natur des Oberfläachenmodifikators ist dabei von besonderer Bedeutung, d.h. mit Maleinsäaurenhydrid modifiziertes Polypropylen erwies sich als der effektivste der untersuchten Modifikatoren. Halogenierte Elastomere und mit einem Phenolharz modifiziertes Polypropylen verbessern das Brandverhalten der Composite. Außerdem häangen die Eigenschaften von der Größe der Holzfasern ab. Die morphologische Untersuchung von Bruchfläachen der Composite zeigte, daß die Grenzfläachenadhäasion durch das mit Maleinsäaureanhydrid modifizierte Polypropylen verbessert wird.
    Notes: The effect of surface treatment of saw dust on the physico-mechanical properties of saw dust-filled polypropylene composites was studied. Whereas the elastomer-pretreated saw dust decreases the strength of composites, in-situ addition of interface modifiers, such as maleated polypropylene, m-phenylene bismaleimideSystematic name: N-(3-maleimidophenyl)maleimide.-modified polypropylene, during kneading of polypropylene with untreated or elastomer-pretreated saw dust improved the mechanical properties with a marginal sacrifice of impact strength. The chemical nature of interphase modifiers played an important role on the mechanical properties of the composites, e.g., maleated polypropylene was most effective among the modifiers used in this study. Halogenated elastomers and phenolic modified polypropylene improved the flame resistant properties of the composites. More over, properties varied with the particle size of wood fiber. The morphological study of the fracture surfaces of composites revealed that interfacial adhesion is improved by adding maleated polypropylene.
    Additional Material: 2 Ill.
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    URL: http://dx.doi.org/10.1002/apmc.1993.052100104
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    Synthesis, conformation, and activity of HCO-Met-ΔZ Leu-Phe-Ome, an active analogue of chemotactic N-formyltripeptides (1993)
    New York : Wiley-Blackwell
    Biopolymers 33 (1993), S. 437-451 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: In order to induce a β-turn conformation into the chemotactic linear tripeptide N-formyl-L-methionyl-L-leucyl-L-phenylalanine (fMLP), the new analogue N-formyl-L-methionyl-ΔZleucyl-L-phenylalanine methyl ester [ ΔZLeu]2f MLP-OMe (1) has been synthesized. The conformational and biochemical consequences of this chemical modification have been determined. Analogue 1 has been synthesized by using N-carboxy-(Z)-α,β-didehydroleucine anhydride as key compound to introduce the unsaturated residue at the central position of the tripeptide 1. The x-ray analysis shows that 1 adopts in the crystal a type II β-turn conformation in which the new residue occupies the (i + 2) position, and an intramolecular H bond is formed between the formylic oxygen and the Phe NH. 1H-nmr analysis based on nuclear Overhauser effect measurements suggests that the same folded conformation is preferred in CDCl3 solution; this finding is also supported by molecular dynamics simulation. The biological activity of 1 has been determined on human neutrophils (polymorphonuclear leukocytes) and compared to that shown by f MLP-OMe. Chemotactic activity, granule enzyme release, and superoxide anion production have been determined. Analogue 1 is practically inactive as chemoattractant, highly active in the superoxide generation, and similar to the parent in the lysozyme release. The conformational restriction imposed on the backbone by the presence of the unsaturated residue is discussed in relation with the observed bioselectivity. © 1993 John Wiley & Sons, Inc.
    Additional Material: 8 Ill.
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    URL: http://dx.doi.org/10.1002/bip.360330310
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    Masthead (1993)
    New York : Wiley-Blackwell
    Biopolymers 33 (1993) 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360330401
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  • 83
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    Effects of molecular association on structure and dynamics of a collagenous peptide (1993)
    New York : Wiley-Blackwell
    Biopolymers 33 (1993), S. 521-533 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Peptide GVKGDKGNPGWPGAPY from the triple-helix domain of type IV collagen aggregates in solution at a critical aggregation concentration of 18 mM. This molecular self association process is investigated by 1H- and 13C-nmr spectroscopy. As a function of increasing peptide concentration, selective 1H resonances are cooperatively chemically shifted by up to 0.04 ppm to apparently saturable values at high concentration. Pulsed field gradient nmr was used to derive translation diffusion constants that, as the peptide concentration is increased, also cooperatively and monotonically decrease to an apparent limiting value. An average number of 6 monomer units per aggregate have been estimated from diffusion constant and 13C relaxation data. Comparative 1H nuclear Overhauser effect spectroscopy (NOESY) spectra accumulated at high and low peptide concentrations suggest that average internuclear distances are decreased as a result of peptide association. 13C-nmr multiplet spin-lattice relaxation and 13C- {1H} NOE effects on 13C-enriched glycine methylene positions in the peptide demonstrate that overall molecular tumbling and backbone internal motions are attenuated in the aggregate state. Lowering the solution pD from pD 6 to pD 2 disrupts the aggregate state, suggesting a role for electrostatic interactions in the association process. Based on thermodynamic considerations, hydrophobic interactions also probably act to stabilize the aggregate state. These data are discussed in terms of an nmr/NOE constrained computer-modeled structure of the peptide. © 1993 John Wiley & Sons, Inc.
    Additional Material: 8 Ill.
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    URL: http://dx.doi.org/10.1002/bip.360330403
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    Reversible effects of medium dielectric constant on structural transformation of β-lactoglobulin and its retinol binding (1993)
    New York : Wiley-Blackwell
    Biopolymers 33 (1993), S. 589-598 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The secondary structure transformation of β-lactoglobulin from a predominantly β-structure into a predominantly α-helical one, under the influence of solvent polarity changes is reversible. Independent of the alcohol used  -  methanol, ethanol, or 2-propanol  -  the midpoints of the observed structural transformation occur around dielectric constant ε ≈ 60. The structural change destroying the hydrophobic core formed by the β-barrel structure leads, at room temperature, to the dissociation of the retinol/β-lactoglobulin complex in the neighborhood of dielectric constant ε ≈ 50. However, when the dielectric constant of the medium is raised back to ε ≈ 70 by the decrease of the temperature, both the refolding of BLG into a β-structure and the reassociation of the retinol/β-lactoglobulin complex are observed. The esterification of β-lactoglobulin carboxyl groups has two effects: on the one hand it accelerates the β-strand → α-helix transition induced by alcohols. On the other hand, the esterification of β-lactoglobulin strengthens its interaction with retinol as it may be deduced from the smaller apparent dissociation constant of retinol/methylated β-lactoglobulin complex. The binding of retinol to modified or unmodified β-lactoglobulin has no influence (stabilizing or destabilizing) on the folding changes induced by alcohol. © 1993 John Wiley & Sons, Inc.
    Additional Material: 5 Ill.
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    URL: http://dx.doi.org/10.1002/bip.360330408
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    Design of peptides: Crystal and molecular structure of a 310-helical peptide N-Boc-L-Phe-dehydro-Phe-L-Val-L-Phe-dehydro-Phe-L-Val-Och3 (1993)
    New York : Wiley-Blackwell
    Biopolymers 33 (1993), S. 613-619 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Highly specific peptide structures can be designed by inserting dehydro residues into peptide sequences. The peptide N-Boc-L-Phe-dehydro-Phe-L-Val-L-Phe-dehydro-Phe-L-Val-OCH3, synthesized by conventional procedures, crystallizes from methanol--water mixtures at 4°C in the tetragonal space group P43 with cell parameters a = b = 13.829 ± 0.003 Å, c = 27.587 ± 0.008 Å, V = 5275.5 ± 0.2 Å3, Z = 4, dm = 1.152 ± 0.005 g cm-3, dcal = 1.150 ± 0.005 g cm-3. The overall residual factor R = 0.084 for 2342 reflections, with 2θmax = 140° using CuKα radiation. The backbone torsion angles are θ1 = -171(1)°, ω0 = 168 (1)°, φ1 = 77 (2)°, ψ1 = 41 (2)°, ωl = 169 (1)°, φ2 = -46 (2)°, ψ2 = -24 (2)°, ω2 = 179 (1)°, φ3 = -63 (2)°, φ3 = -19 (2)°, ω3 = 171 (1)°, φ4 = -67 (2)°, ψ4 = -8 (1)°, ω4 = 169 (1)°, ψ5 = -61 (1)°, φ5 = -26(1)°, ω5 = 177(1)°, ψ6 = -122 (1)°, φ6T = 26 (2)°. The peptide adopts a 310-helical conformation with three intramolecular hydrogen bonds (i + 3 → i) involving carbonyl oxygen atoms of Phe1, dehydro-Phe2, Val3, and the NH groups of Phe4, dehydro-Phe5, and Val6 with distances of 3.01 (1), 2.82 (1), and 3.09 (2) Å, respectively. The structure determination revealed that a hexapeptide with two dehydro-Phe residues at (i + 2) and (i + 5) positions generates a 310-helical conformation. The helical peptide molecules are arranged in a major helical arrangement about the 43axis. These helices are packed parallel to the c axis and form several interdigitating hydrogen bonds. The interhelix hydrogen-bonding regions are separated by van der Waals interactions involving the side chains of Phe, dehydro-Phe, and Val residues. © 1993 John Wiley & Sons, Inc.
    Additional Material: 3 Ill.
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  • 86
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    Cyanogen as a selective probe for carbonic anhydrase hydrolase activity (1993)
    New York : Wiley-Blackwell
    Biopolymers 33 (1993), S. 687-692 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The salt bridge probe cyanogen (ethanedinitrile, C2N2; N≡C--C≡N) inhibits the bovine carbonic anhydrase (EC 4.2.1.1.) hydrolase activity toward various types of esters without significant effect on its hydrolyase activity. Two sets of pyridine derivatives that were isosteric substrates for the two activities were differentially affected. Acetazolamide and salamide are reversible inhibitors of the enzyme; only salamide affords protection of the hydrolase activity against the action of C2N2. Since each is known to bind in different positions within the active site, the selective effect of salamide may arise from its position covering one CO2 site as well as a site important for hydrolase activity. The C2N2 concentration dependence of the time course of hydrolase inhibition is consistent with the existence of a high C2N2 affinity site with slow covalent change and a second site with lower C2N2 affinity, but higher rate of covalent modification of the enzyme. © 1993 John Wiley & Sons, Inc.
    Additional Material: 3 Ill.
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    URL: http://dx.doi.org/10.1002/bip.360330417
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  • 87
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    Masthead (1993)
    New York : Wiley-Blackwell
    Biopolymers 33 (1993) 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360330501
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  • 88
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    Molecular dynamics of sickle and normal hemoglobins (1993)
    New York : Wiley-Blackwell
    Biopolymers 33 (1993), S. 735-742 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Molecular dynamics (MD) simulations have been carried out for 62.5 ps on crystal structures of deoxy sickle cell hemoglobin (HbS) and normal deoxy hemoglobin (HbA) using the CHARMM MD algorithm, with a time step of 0.001 ps. In the trajectory analysis of the 12.5-62.5 (50 ps) simulation, oscillations of the radius of gyration and solvent-accessible surface area were calculated. HbS exhibited a general contraction during the simulation, while HbA exhibited a nearly constant size. The average deviations of simulated structures from the starting structures were found to be 1.8 Å for HbA and 2.3 Å for HbS. The average rms amplitudes of atomic motions (atomic flexibility) were about 0.7 Å for HbA and about 1.0 Å for HbS. The amplitudes of backbone motion correlate well with temperature factors derived from x-ray crystallography. A comparison of flexibility between the α- and β-chains in both HbA and HbS indicates that the β-chains generally exhibited greater flexibility than the α-chains, and that the HbS β-chains exhibit greater flexibility in the N-terminal and D- and F-helix regions than do those of HbA. The average amplitude of backbone torsional oscillations was about 9°, a value comparable with that of other simulations, with enhanced torsional oscillation occurring primarily at the ends of helices or in loop regions between helices. Comparison of atomic flexibility and torsional oscillation results suggests that the increased β-chain flexibility results from relatively concerted motions of secondary structure elements. The increased flexibility may play an important role in HbS polymerization. Time course analysis of conformational energy of association, hydrogen bonding and hydrophobic bonding (as calculated from solvent accessibility) shows that all three of these factors contribute to the stability of subunit association for both hemoglobins. © 1993 John Wiley & Sons, Inc.
    Additional Material: 7 Ill.
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    URL: http://dx.doi.org/10.1002/bip.360330503
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  • 89
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    Hydrodynamic modes of arbitrarily shaped flexible macromolecules: Influence on dynamic light scattering (1993)
    New York : Wiley-Blackwell
    Biopolymers 33 (1993), S. 409-436 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The diffusional motions of flexible macromolecules are analyzed with an increasingly realistic Rouse-Zimm model, i.e., by modeling the molecule as an arbitrary set of spheres connected by nearly harmonic springs. New features include (1) nearly arbitrary arrangements of spheres, (2) arbitrary arrangements of translational and torsional springs, (3) significant anharmonic corrections to the elastic potential surface, and (4) inclusion of torsional damping and various hydrodynamic cross-coupling effects (including two types of translational-rotational coupling) with no additional fitted parameters.The hydrodynamic interactions [R. F. Goldstein (1985) Journal of Chemical Physics, Vol. 83, pp. 2390-2397] contain no adjustable parameters other than temperature, viscosity, and the radii and positions of the spheres. These hydrodynamic interactions allow accurate calculations of rigid body diffusion as well as flexible motions.Given the positions, radii, and spring constant matrix, one can calculate a full set of three-dimensional diffusional modes. Because one uses an off-diagonal hydrodynamic resistance matrix instead of a diagonal mass matrix, the diffusional modes are different in structure from vacuum normal modes, and give rise to different rms motions in the laboratory frame. These hydrodynamic modes include the effects of vibrational-translational cross-coupling (i.e., motion along a vibrational coordinate may give rise to a translational force, and vice versa).The diffusional modes are used to simulate dynamic light scattering (DLS). I examine various molecules with different shapes, flexibilities, and with different scattering vectors. Radial and angular motions influence DLS decays differently. These effects are dependent upon the molecular shape (straight, bent, or curved) and type of flexibility (stretching or bending). Furthermore, small cubic corrections to the potential surface can be significant for DLS of certain geometries such as straight rods and semicircles. © 1993 John Wiley & Sons, Inc.
    Additional Material: 12 Ill.
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    URL: http://dx.doi.org/10.1002/bip.360330309
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  • 90
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    Calcium-dependence of laminin binding to phospholipid membranes (1993)
    New York : Wiley-Blackwell
    Biopolymers 33 (1993), S. 475-477 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Laminin is the most abundant noncollagenous protein in basement membranes. Its selfassembly has been studied in solution, and it has been established that calcium ions induce partially reversible aggregation. The behavior at a lipid membrane surface is of greater biological significance, but it is difficult to study quantitatively binding kinetics at a surface. The present work uses a powerful new integrated optics technique to measure the absorption and aggregation of the laminin-nidogen at a bilayer lipid membrane surface. It is found that the binding of a single layer of laminin at the lipid membrane is independent of the presence of calcium, but that the building up of multilayer laminin membranes requires calcium, and that these may not be destroyed by a calcium-complexing agent. © 1993 John Wiley & Sons, Inc.
    Additional Material: 1 Ill.
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    URL: http://dx.doi.org/10.1002/bip.360330313
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  • 91
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    Second international conference on “Polymers for advanced technologies” (PAT '93) oxford, United Kingdom (1993)
    New York : Wiley-Blackwell
    Biopolymers 33 (1993), S. 511-511 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360330317
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  • 92
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    1H, 13C, and 15N assignments and secondary structure of the FK506 binding protein when bound to ascomycin (1993)
    New York : Wiley-Blackwell
    Biopolymers 33 (1993), S. 535-550 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The 1H, 13C, and 15N resonances of FKBP when bound to the immunosuppressant, ascomycin, were assigned using a computer-aided analysis of heteronuclear double and triple resonance three-dimensional nmr spectra of [U-15N] FKBP/ascomycin and [U-15N, 13C] FKBP/ascomycin. In addition, from a preliminary analysis of two heteronuclear four-dimensional data sets, 3JHN,Hα coupling constants, amide exchange data, and the differences between the Cα and Cβ chemical shifts of FKBP to random coil values, the secondary structure of FKBP when bound to ascomycin was determined. The secondary structure of FKBP when bound to ascomycin in solution closely resembled the x-ray structure of the FKBP/FK506 complex but differed in some aspects from the structure of uncomplexed FKBP in solution. © 1993 John Wiley & Sons, Inc.
    Additional Material: 9 Ill.
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    URL: http://dx.doi.org/10.1002/bip.360330404
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  • 93
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    Physicochemical properties of (1 → 6)-branched (1 → 3)-β-D-glucans. 1. Physical dimensions estimated from hydrodynamic and electron microscopic data (1993)
    New York : Wiley-Blackwell
    Biopolymers 33 (1993), S. 561-573 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The physical dimensions of several (1 → 6) branched (1 → 3) -β-D-glucan samples obtained from different organisms and their derivatives have been studied by electron microscopy, light scattering measurements, viscometry, and gel permeation chromatography. The electron micrographs indicate that in most samples these biopolymers are adequately described as linear worm-like coils. A sample reconstituted from alkaline media appeared as a blend of the linear, circular, and aggregated polymer morphologies. The average mass per unit length, ML = Mw/Lw for the macroscopically linear samples, was estimated to be 2100 ± 200 g mol-1 nm-1. The parameter mL was determined from the contour lengths obtained by electron microscopy and the molecular weight by light scattering measurements. The observed ML was consistent with the triple-helical structure reported from x-ray diffraction studies and observed degree of side-chain substitution. From the molecular snapshots shown in the electron micrographs, the persistence lengths of these β-D-glucans were determined to be 140 ± 30 nm. The experimentally determined intrinsic viscosities were consistent with these estimates of ML and persistence length. Comparison of the molecular weight distributions obtained from gel permeation chromatography and those deduced from the electron micrographs indicates that number and weight average contour lengths are more reliable than z and z + 1 averages. © 1993 John Wiley & Sons, Inc.
    Additional Material: 9 Ill.
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    URL: http://dx.doi.org/10.1002/bip.360330406
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  • 94
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    Rayleigh scattering of Mössbauer radiation in hydrated oriented DNA fibers (1993)
    New York : Wiley-Blackwell
    Biopolymers 33 (1993), S. 633-638 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The Rayleigh scattering of Mössbauer radiation has been measured on oriented hydrated fibres of A-NaDNA. The elastic and inelastic scattering intensities have been determined at different temperatures from 275 to 310 K in the Q range 0.7-3.3 Å-1. The elastic intensity has a main maximum at Q = 1.92 Å-1 due to an ordered structure of water along the DNA double helices. From the temperature dependence of the elastic intensity under the water peak maximum, the mean square displacement of water oxygens in the direction parallel to the DNA axis has been deduced. It varies from 0.110 Å2 at 275 K up to 0.345 Å2 at 310 K. The thermal diffuse scattering intensity is also peaked at the same Q value of the elastic intensity, indicating the presence of coherent vibrational excitations propagating along the ordered water filaments. © 1993 John Wiley & Sons, Inc.
    Additional Material: 7 Ill.
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    URL: http://dx.doi.org/10.1002/bip.360330412
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  • 95
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    Characterization of the bioactive form and molecular determinants of recognition of cyclic enkephalin peptides at the δ-opioid receptor (1993)
    New York : Wiley-Blackwell
    Biopolymers 33 (1993), S. 647-657 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: An extensive and systematic search strategy to determine the conformational profile of 12 cyclic disulfide-bridged opioid peptides with varying affinities at the δ receptor has been carried out to identify the structure that is recognized by the δ receptor for each analogue. The methods and procedures used here for the conformational search have already been validated for [D-Pen2, D-Pen5] enkephalin (DPDPE), one member of this family. Use of these methods led to a low-energy solution conformation of DPDPE in excellent agreement with all the geometric properties deduced from its solution nmr spectra. Each of the analogue was subjected to the same procedure, involving a combination of molecular dynamics simulations at high and low temperature. The study was repeated in two environmental conditions, an apolar environment, simulated by using a distance-dependent dielectric constant, and a polar environment by embedding the peptides in a high constant dielectric ( ε = 80). An automated comparison of the different conformers based on their backbone rms and average distance between the key aromatic moieties was followed by graphic analysis using maximum structural overlap. The cross-comparison of the conformations for each analogue revealed a unique conformer that may be recognized by the δ receptor for each high-affinity analogue that permitted maintaining the critical elements required for recognition in a simple spatial orientation, while maximizing similarity in other regions. © 1993 John Wiley & Sons, Inc.
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    URL: http://dx.doi.org/10.1002/bip.360330414
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  • 96
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    Second International Conference on “Polymers for Advanced Technologies” (PAT '93) Oxford, United Kingdom (1993)
    New York : Wiley-Blackwell
    Biopolymers 33 (1993), S. 723-723 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360330421
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  • 97
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    Lattice vibrations in crystalline L-alanine (1993)
    New York : Wiley-Blackwell
    Biopolymers 33 (1993), S. 725-733 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Zwitterionic L-alanine forms crystals containing strong hydrogen-bonding and methyl-methyl interactions. Well-defined low-frequency lattice vibrations exist in the crystals involving correlated intermolecular motions on the picosecond timescale. A characterization of these vibrations is expected to provide useful information on the nature of nonbonded interactions in peptides and proteins. We examine some of the vibrations using coherent inelastic neutron scattering and computer simulation techniques. The neutron scattering measurements are used to determine phonon dispersion relations for the acoustic and some low-frequency optic modes in the crystal. There is evidence for interaction between the two lowest frequency optical phonons and the longitudinal acoustic mode. The velocity of sound is anisotropic and can be correlated with the hydrogen-bonding arrangement in the crystal. Corresponding phonon dispersion relations are derived from normal mode analyses of the crystal using the program CHARMM. Although some calculated vibrational frequencies are somewhat too high, the form of the calculated dispersion relations are in good agreement with experiment. © 1993 John Wiley & Sons, Inc.
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    URL: http://dx.doi.org/10.1002/bip.360330502
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    A proton magnetic resonance study of two synthetic agonist-antagonist pairs of bradykinin analogues (1993)
    New York : Wiley-Blackwell
    Biopolymers 33 (1993), S. 769-780 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The conformation of two agonist-antagonist pairs of bradykinin (Arg1-Pro2-Pro3-Gly4-Phe5-Ser6-Pro7-Phe8-Arg9) analogues were studied in CD3OH/H2O solution by 1H-nmr techniques. The first agonist peptide studied, D-Arg0-Arg1-Pro2-Hyp3-Gly4-Thi5-Ser6-Pro7-Thi8-Arg9, differs from the bradykinin sequence by the addition of D-Arg0, the replacement of the Phe moieties in positions 5 and 8 by Thi (Thi = β-(2-thienyl)-L-alanine), and Hyp3 (Hyp = L-4-hydroxy-L-proline) in position 3. In the corresponding antagonist sequence, Pro7 is replaced by D-Phe7. The second agonist-antagonist pair studied does not contain the D-Arg0 residue, which is present only to slow down the rate of metabolism. Based on complete resonance assignments from two-dimensional total correlation spectroscopy and rotating frame nuclear Overhauser effect spectroscopy spectra at 500 MHz, the peptides were analyzed in terms of intraresidue, sequential, and medium-range nuclear Overhauser effects, amide proton temperature coefficients, and vicinal coupling constants. Both agonist peptides show clear evidence for the existence of a type I β-turn comprising the C-terminal residues Ser6-Pro7-Thi8-Arg9 in fast conformational equilibrium with extended structures throughout. Although the conformational space is dominated by extended structures, the presence of the β-turn is spectroscopically clearly discernible. The two antagonist peptides, on the other hand, do not show evidence of turn formation but rather the presence of an extended conformation with some irregularities in the N-terminal region of the peptide. While the existence of a turn at the C-terminal end of bradykinin and its analogues with agonist activity has been predicted by empirical calculations and measurements in very apolar solvents, this study, for the first time, provides evidence based on physical data in a polar solvent environment that the turn is present, that it is type I and that it is essential for agonist activity. In the particular solvent used in these studies, the Pro7 to D-Phe7 substitution precluded the formation of the turn for the C-terminal residues of the antagonist. © 1993 John Wiley & Sons, Inc.
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    URL: http://dx.doi.org/10.1002/bip.360330506
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  • 99
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    Editorial (1993)
    New York : Wiley-Blackwell
    Biopolymers 33 (1993), S. 1001-1001 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360330702
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  • 100
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    Improved molecular dynamics simulations for the determination of peptide structures (1993)
    New York : Wiley-Blackwell
    Biopolymers 33 (1993), S. 1003-1017 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: In this article a few methods or modifications proven to be useful in the conformational examination of peptides and related molecules by molecular dynamics are illustrated. The first is the explicit use of organic solvents in the simulations. For many cases such solvents are appropriate since the nmr measurements (or other experimental observations) were carried out in the same solvent. Here, the use of dimethylsulfoxide and chloroform in molecular dynamics is described, with some advantages of the use of these solvents highlighted.A constant allowing for the scaling of the nonbonded interactions of the force field, an idea previously employed in distance geometry and simulated annealing, has been implemented. The usefulness of this method is that when the nonbonded term is turned to zero, atoms can pass through each other, while the connectivity of the molecule is maintained. It will be shown that such simulations, if a sufficient driving force is present (i.e., nuclear Overhauser effects restraints), can produce the correct stereoconfiguration (i.e., chiral center) as well as configurational isomer (i.e., cis/trans isomers).Lastly, a penalty term for coupling constants directly related to the Karplus curve has been plemented into the potential energy force field. The advantages of this method over the commonly used dihedral angle restraining are discussed. In particular, it is shown that with more than one coupling constant about a dihedral angle a great reduction of the allowed conformational space is obtained. © 1993 John Wiley & Sons, Inc.
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    URL: http://dx.doi.org/10.1002/bip.360330703
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