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  • 1990-1994  (4,234)
  • 1975-1979
  • 1960-1964
  • 1992  (4,234)
  • Polymer and Materials Science  (4,164)
  • Electron microscopy
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  • 1990-1994  (4,234)
  • 1975-1979
  • 1960-1964
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  • 1
    Electronic Resource
    Electronic Resource
    Cell populations in the lesion of human cutaneous leishmaniasis: A light microscopical, immunohistochemical and ultrastructural study (1992)
    Springer
    Virchows Archiv 421 (1992), S. 239-247 
    Details
    ISSN: 1432-2307
    Keywords: Human cutaneous leishmaniasis ; Skin ; Immunohistochemistry ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary To characterize the in situ cellular immune response in localized cutaneous leishmaniasis (LCL), the authors studied frozen skin biopsies from 50 patients with LCL due toLeishmania braziliensis guyanensis. A panel of 31 monoclonal antibodies was used, which defined the number and distribution of inflammatory cell subsets. Skin inflammatory infiltrates were composed of T cells (with a local CD4/CD8 ratio of 1.05±0.7 vs 1.48±0.3 in peripheral blood), macrophages and a smaller number of B cells, natural killer cells and granulocytes. Most of the T cells expressed activation markers (interleukin-2 and transferrin receptors, HLA-DR+) and an increase in T-cell-receptorγδ expression was noted. Analysis of the CD4+ subpopulations with newly available reagents showed that helper T cells (CD4+CD45RO+) exceeded the suppressor/inducer subset (CD4+CD45RA+) by 1.4∶1. There were no differences between local immune variables from patients with primary infection (45 patients) and those with recurrence (5). In 7 patients, biopsies were analysed before and 1 month after specific treatment, and did not show significant differences except for a small increase of dermal CD1a+ (Langerhans) cells/mm2. The observed pattern of cellular skin infiltration suggests an immune-mediated tissue injury including T-cell-mediated cytotoxicity and delayed hypersensitivity reactions in addition to direct parasitic action.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01611181
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  • 2
    Electronic Resource
    Electronic Resource
    The glomerular mesangium: capillary support function and its failure under experimental conditions (1992)
    Springer
    Journal of molecular medicine 70 (1992), S. 843-856 
    Details
    ISSN: 1432-1440
    Keywords: Kidney ; Glomerulus ; Mesangium ; Mesangial failure ; Electron microscopy ; Animal models
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary We present a structural analysis of the ability of the biomechanical unit consisting of mesangium and glomerular basement membrane to maintain normal capillary architecture in the face of mechanical challenges due to high intraglomerular pressures. Capillary support function may be considered in terms of the stabilization of local form (development of wall tension against capillary dilation) and global form (centripetal fixation of capillary loops to maintain higher order form). The pathologic consequences of the loss of this support are illustrated by way of experimental models of mechanical mesangial failure. Such failure may express itself as mesangial widening, increased transmesangial macromolecule “traffic,” ballooning of capillary segments, and unfolding of capillary loops. Mechanisms are described by which these structural changes may lead to segmental glomerular sclerosis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00180755
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  • 3
    Electronic Resource
    Electronic Resource
    A unique case of naturally occurring mummification of human brain tissue (1992)
    Springer
    International journal of legal medicine 105 (1992), S. 173-175 
    Details
    ISSN: 1437-1596
    Keywords: Human brain tissue ; Natural mummification ; Histology ; Histochemistry ; Electron microscopy ; Elemetal analysis ; Gehirn ; Mensch ; Naturaliche Mumifikation ; Histologie ; Histochemie ; Elektronenmikroskopie ; Atmospektralanalyse
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Law
    Description / Table of Contents: Zusammenfassung Bei Ausgrabungen in Bulgarien wurden Schädel und Knochen von 39 Individuen im Alter zwischen 35 und 60 Jahren, die vor ca. 45–50 Jahren begraben wurden, gefunden. Bei der nachfolgenden gerichtsmedizinischen Experitse wurden in zwei intakten Schädeln und zwischen den Knochen anderer Schädel sieben harte Gebilde (zwei ganze und fünf Fragmente), die wie geschrumpfte menschliche Gehirne aussahen, identifiziert. Entsprechende Proben von diesem Material wurden für 3–4 Tage mit 15% wässriger Lösung von Glycerol weicher gemacht und danach lichtmikroskopisch und elektronenmikroskopisch untersucht. An entsprechenden Stückchen von frischem menschlichem Gehirn und den gefundenen Proben wurde eine Atomspektral-analyse zur Bestimmung des chemischen Bestandes an Elementen durchgeführt. Die komplexe Untersuchung des Materials ergab, daß es sich bei diesem Fund um einen Sonderfall von natürlich mumifizierten menschlichen Gehirnen handelt, die durch sonderbare Bedingungen nur im Schädel der begrabenen Individuen entstanden sind.
    Notes: Summary When skulls and bones were exhumed from a mass grave in Bulgaria and subjected to medicolegal examination they were found to originate from 39 humans aged 36–60 years old who had been buried approximately 45–50 years ago. Solid structures which strongly resembled shrunken human brain tissue were found inside 2 intact skulls. Among other bones 5 similar structures were found one of which was an almost entirely preserved human brain, and the others were fragments from different regions of the human brain. Samples of these structures were immersed in 15% aqueous glycerol solution to soften and were examined by light and electron microscopy. Sampels of this material and of fresh human brain were subjected to elementary atomic spectral analysis. These complex studies indicated the samples to be naturally mummified human brain tissue and that this process had occurred due to specific conditions within the cranial cavities after burial.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01625172
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  • 4
    Electronic Resource
    Electronic Resource
    Vascular and myofibrillar lesions in acute myoglobinuria associated with carnitine-palmityl-transferase deficiency (1992)
    Springer
    Virchows Archiv 421 (1992), S. 57-64 
    Details
    ISSN: 1432-2307
    Keywords: Carnitine-palmityl-transferase deficiency ; Acute vascular lesions ; Acute myofibrillar lesions ; Ischaemia ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary A case of severe exercise-induced myoglobinuria in a 14-year-old boy suffering from a carnitine-palmityl-transferase (CPT) defect is reported. Biopsies of the forearm muscle were examined using light and electron microscopy in the acute and recovery phases of the illness. The first biopsy showed the presence of scattered foci of necrosis where necrotic fibres with occasional disruptions of the basal lamina were seen around injured capillaries. Various degrees of damage and different stages of evolution were found in these foci, which also contained regenerating muscle fibres. In the second biopsy, performed 2 weeks later, most of the fibres displayed a normal structure. Necrosis was no longer present. However, in some areas perivascular fibrosis was prominent, the fibres were small and irregularly shaped, and their nuclei often centrally located. These data strongly suggest that circulatory disorders and ischaemia, brought about by premature acute metabolic imbalance, could be involved in the development of exerciseinduced myolysis observed in CPT deficiency. The risk of fibrous cardiomyopathy in these patients is pointed out.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01607140
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  • 5
    Electronic Resource
    Electronic Resource
    The pathobiology of salivary gland (1992)
    Springer
    Virchows Archiv 421 (1992), S. 105-113 
    Details
    ISSN: 1432-2307
    Keywords: Parotid gland ; ras ; Transgenic mouse ; Electron microscopy ; Immunocytochemistry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary In the transgenic TG.SH (mouse mammary tumour virus/v-Ha-ras) mouse, designed to develop mammary tumours, occasional spontaneous salivary gland tumours have been reported, predominantly in males. The incidence and histomorphology of salivary gland tumours in 73 TG.SH mice were surveyed and in total, 21.9% developed both overt and microscopic parotid tumours. The majority developed between 73 and 150 days of age. In 31.5% of the TG.SH mice, occasional unilateral, but more frequently bilateral exophthalmos due to hyperplasia of the intraorbital (Harderian) lacrimal gland was observed. In 70% of these animals, parotid tumours developed later. Since Harderian gland hyperplasia, occurring as early as 5 weeks of age, preceded the development of palpable salivary gland lesions, this stigma is useful for the early selection of animals likely to progress to tumour formation. Before tumour-bearing transgenic mice are considered to be suitable models of human neoplastic disease, morphological characterization is necessary to ensure that the tumours are histologically representative of the human lesions for which they are potential models. In this study, all parotid tumours consisted of acinar-like glandular structures with central lumina discernible by electron microscopy. Ultrastructurally, secretory granules evident in the apical cytoplasm of the tumour cells resembled the zymogen granules of the normal parotid acinar cell, and some cells had a prominent complement of rough endoplasmic reticulum. These features, along with focal amylase expression detected immunohistochemically in some parotid tumours, identified these neoplasms as acinic cell carcinomas that mimic the human salivary gland acinic cell carcinoma faithfully.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01607042
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  • 6
    Electronic Resource
    Electronic Resource
    Electron microscopic study of paired helical filaments and cerebral amyloid using a novel en bloc silver staining method (1992)
    Springer
    Virchows Archiv 420 (1992), S. 519-525 
    Details
    ISSN: 1432-2307
    Keywords: Silver staining ; Paired helical filaments ; Cerebral amyloid ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary A one step en bloc silver staining method which was originally established to study nucleolar organizer regions has been applied for the demonstration of both paired helical filaments (PHF) and extracellular cerebral amyloids in semi-thin sections and at the electron microscopic level. The three forms of PHF can be visualized: (1) neurofibrillary tangles are shown in all stages from first appearance in form of intracellular patches of PHF to severely degenerated shadow-like “ghost” tangles; (2) neuropil threads are distinctly stained in great numbers; and (3) PHF are easily detected as neuritic components in amyloid plaques. All forms of fibrillar extracellular amyloid structures, i.e. “diffuse”, “classical” and “burnt out” plaques, are well demonstrated; congophilic angiopathy reveals amyloid preferentially in arteries and arterioles of the leptomeninges and cortex ranging from small circumscribed patches to large circumferential amounts with occasional plaque-like condensations or broad loose accumulations of amyloid; perivascular cuffs and laminar subpial deposits of amyloid are stained as well. At the electron microscopic level all lesions are clearly visible in non uranyl/lead-stained specimens, characterized by varying numbers of silver grains on a pale background. The detailed demonstration of structures in archival material, which had been stored in paraffin and re-embedded for electron microscopy, is due to the demonstration of argyrophilic structures by the protective colloidal developer of gelatin and formic acid and to the proteolytic resistance of insoluble PHF and extracellular amyloids in plaques and congophilic angiopathy.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01600257
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  • 7
    Electronic Resource
    Electronic Resource
    Malignant paraganglioma of the uterus (1992)
    Springer
    Virchows Archiv 420 (1992), S. 453-457 
    Details
    ISSN: 1432-2307
    Keywords: Uterus ; Paraganglioma ; Intracytoplasmic hyaline globules ; Immunohistochemistry ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary We report a malignant uterine paraganglioma in a 40-year-old female, who died 7 months after the initial diagnosis. On light microscopy the tumour showed a typicalzellballen pattern as well as a pronounced cellular pleomorphism. In many tumour cells hyaline globules were demonstrated within the cytoplasm. Immunohistochemically the lesion was characterized by the presence of neuron-specific enolase, protein gene product 9.5 and synaptophysin, and electron microscopically by the occurrence of neurosecretory granules.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01600518
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  • 8
    Electronic Resource
    Electronic Resource
    Occlusive microangiopathy by immunoglobulin (IgM-kappa) precipitation: pathogenetic relevance in paraneoplastic cryoglobulinemic neuropathy (1992)
    Springer
    Acta neuropathologica 83 (1992), S. 423-426 
    Details
    ISSN: 1432-0533
    Keywords: Peripheral neuropathy ; Cryoglobulinemia ; Immunohistochemistry ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Histological, immunohistochemical and ultrastructural sural nerve and skin biopsy findings in a case of cryoglobulinemia secondary to an IgM-kappa-producing non-Hodgkin lymphoma are described. The main finding was an occlusive microangiopathy present in both the sural nerve and the skin. Widespread cryoglobulin deposits of the proliferated vasa nervorum were associated with pronounced changes probably evoked by ischemia. Moderate perivascular inflammation, but no florid vasculitis was additionally present. Our observations indicate that occlusive microangiopathy by precipitated cryoglobulins may be a relevant pathogenetic factor in cryoglobulinemic peripheral neuropathy.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00713536
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  • 9
    Electronic Resource
    Electronic Resource
    Presenile dementia with progressive supranuclear palsy tangles and Pick bodies: an unusual degenerative disorder involving the cerebral cortex, cerebral nuclei, and brain stem nuclei (1992)
    Springer
    Acta neuropathologica 84 (1992), S. 128-134 
    Details
    ISSN: 1432-0533
    Keywords: Progressive supranuclear palsy ; Neurofibrillary tangles ; Pick body ; Immunocytochemistry ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Degeneration of heterogeneous systems in the central nervous system, with widespread distribution of argyrophilic neuronal fibrillary inclusions, was found in a patient with presenile dementia. Atrophy was circumscribed in the frontal and temporal lobes. Neuronal loss was severe in the basal ganglia, subthalamic nucleus, and substantia nigra. Immunocytochemical study using anti-phosphorylated tau and anti-ubiquitin antibodies in conjunction with ultrastructural observations revealed two types of inclusions: neurofibrillary tangles (NFTs) of progressive supranuclear palsy (PSP) in the Edinger-Westphal nucleus, locus coeruleus, cerebellar dentate nucleus, inferior olivary nucleus, and posterior horn of the spinal cord; and Pick bodies (PBs) in the atrophied cerebral cortex and red nucleus. PSP-type NFTs and PBs have been demonstrated in a single case for the first time. Despite their pathognomonic significance in certain disorders, we suggest that these inclusions may reflect a form of cytoskeletal disorganization, which is not entirely restricted to a single disease entity.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00311384
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  • 10
    Electronic Resource
    Electronic Resource
    Sural nerve immunoreactivity for nerve growth factor receptor in a case of localized hypertrophic neuropathy (1992)
    Springer
    Acta neuropathologica 83 (1992), S. 547-553 
    Details
    ISSN: 1432-0533
    Keywords: Localized hypertrophic neuropathy ; Electron microscopy ; Immunohistochemistry ; Nerve growth factor receptor ; Schwann cells
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Immunoreactivity for nerve growth factor receptor (NGFR) was examined using a monoclonal antibody against human NGFR in the sural nerve of a 24-year-old woman, affected by localized hypertrophic neuropathy (LHN). NGFR expression was correlated with electron microscopy and with immunoreactivity for S-100 protein, laminin, HLA-DR, HNK-1, P0 glycoprotein and neurofilament peptides. Our results indicate that in LHN most of whorl-forming cells are NGFR positive and S-100 protein or HLA-DR negative. These data along with the ultrastructural features suggest their origin from perineurium.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00310035
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  • 11
    Electronic Resource
    Electronic Resource
    Immunohistochemistry of cholinergic receptors (1992)
    Springer
    Anatomy and embryology 186 (1992), S. 407-429 
    Details
    ISSN: 1432-0568
    Keywords: Acetylcholine receptors ; Immunocytochemistry ; Electron microscopy ; Human motor endplate ; Human cerebral cortex ; Neurodegenerative disorders
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Acetylcholine and its receptors are involved in a variety of important signal transduction processes. As shown here paradigmatically for the human neuromuscular junction and the cerebral cortex, acetylcholine receptors can be visualized immunohistochemically at the cellular and subcellular level under physiological and pathological conditions. At normal motor endplates nicotinic cholinoceptors are localized at the surface of the postsynaptic junctional folds. In myasthenic syndromes investigation of muscle biopsies enables the diagnosis of receptor deficiencies at the ultrastructural level. In normal cerebral cortex pyramidal neurons are equipped with both nicotinic and muscarinic acetylcholine receptors localized to postsynaptic densities. In neuropsychiatric diseases cholinoceptor expression can be monitored at the cellular level by quantititative assessment of immunolabeled cortical neurons.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00185457
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  • 12
    Electronic Resource
    Electronic Resource
    Ultrastructural study of ascending projections to the lateral mammillary nucleus of the rat (1992)
    Springer
    Anatomy and embryology 185 (1992), S. 547-557 
    Details
    ISSN: 1432-0568
    Keywords: Dorsal tegmental nucleus of Gudden ; Laterodorsal tegmental nucleus ; Synaptic organization ; Anterograde tracing study ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary We examined the synaptic organization of ascending projections from the pars ventralis of the dorsal tegmental nucleus of Gudden (TDV) and the laterodorsal tegmental nucleus to the lateral mammillary nucleus (LM). The LM neuropil consists of terminals containing pleomorphic synaptic vesicles and forming symmetric synaptic contact, and terminals containing round synaptic vesicles and forming asymmetric synaptic contact. They make up 63% and 37%, respectively, of all axodendritic terminals. All axosomatic terminals contain pleomorphic vesicles and make symmetric contact. Following injection of WGA-HRP into the TDV, many anterogradely labeled terminals and retrogradely labeled cells are found in the LM. Labeled terminals contact mainly proximal (more than 2 μm diameter) and intermediate (1–2 μm diameter) dendrites. Serial ultrathin sections of the LM show that 55% of axosomatic terminals are labeled anterogradely. Following injection of WGA-HRP into the laterodorsal tegmental nucleus, many anterogradely labeled terminals are found in the LM, but no retrogradely labeled cells are present. Labeled terminals contact mainly distal (less than 1 μm diameter) and intermediate dendrites as well as somata. In the LM neurons, 46% of axosomatic terminals are labeled anterogradely. All labeled terminals from these nuclei contain pleomorphic vesicles and make symmetric synaptic contact. These results indicate that almost all axosomatic terminals come from the TDV and the laterodorsal tegmental nucleus, which send inhibitory inputs to the lateral mammillary nucleus.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00185614
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  • 13
    Electronic Resource
    Electronic Resource
    Neuronal autophagic vacuoles in experimental scrapie and Creutzfeldt-Jakob disease (1992)
    Springer
    Acta neuropathologica 83 (1992), S. 134-139 
    Details
    ISSN: 1432-0533
    Keywords: Scrapie ; Creutzfeldt-Jakob disease ; Neuronal autophagy ; Neuropathology ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary We report the presence of autophagic vacuoles (AV) in neuronal perikarya and neuronal processes of rodents with experimental scrapie and Creutzfeldt-Jakob disease. AV were composed of sequestrated cytoplasmic areas containing ribosomes and occasionally mitochondria and small secondary vacuoles. The formation of AV may contribute to neuronal degeneration and ultimately to neuronal loss.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00308472
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  • 14
    Electronic Resource
    Electronic Resource
    Paired helical filaments in astrocytes: electron microscopy and immunohistochemistry in a case of atypical Alzheimer's disease (1992)
    Springer
    Acta neuropathologica 83 (1992), S. 228-232 
    Details
    ISSN: 1432-0533
    Keywords: Alzheimer's disease ; Astrocytes ; Electron microscopy ; Immunohistochemistry ; Paired helical filaments
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary A 54-year-old man who had cerebellar ataxia and pseudobulbar palsy at the age of 29 years, and soon developed dementia, myoclonus and convulsions, died after about 20 years in a vegetative state. Histological examination of the extensively atrophic and devastated brain (680 g) revealed the almost total loss of cerebral cortical neurons associated with numerous β-protein amyloid plaques, many extracellular tangles and a large number of hypertrophic astrocytes, and prominent amyloid angiopathy. The astrocytes were frequently immunopositive for anti-human tau antibody (anti-htau) and anti-ubiquitin antibody (anti-ubi). Double immunostaining with anti-htau and anti-glial fibrillary acidic protein (GFAP) antibody clearly demonstrated htau-positive domains within the GFAP-positive perikarya/and processes of several astrocytes. Electron microscopy of the hippocampal CA1, which was completely devoid of pyramidal neurons, revealed, in astrocytes, abnormal filaments indistinguishable from the paired helical filaments (PHFs) seen in neurons. On immunoelectron microscopy, the filaments were observed to be labeled with anti-htau and anti-ubi, exhibiting the same immunohistochemical features as neuronal PHFs. This is the first demonstration of clearly constricted and both tau- and ubiquitin-positive PHFs in astrocytes, indicating that, in some special conditions like in our case, processes similar to those that attack neurons also affect astrocytes and ultimately make the latter form PHFs.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00296783
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  • 15
    Electronic Resource
    Electronic Resource
    Retinal photoreceptor fine structure in the velvet cichlid (Astronotus ocellatus) (1992)
    Springer
    Anatomy and embryology 186 (1992), S. 363-370 
    Details
    ISSN: 1432-0568
    Keywords: Retinal photoreceptors ; Electron microscopy ; Teleost ; Astronatus ocellatus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The structure and arrangement of the retinal photoreceptors of the velvet cichlid fish (Astronotus ocellatus) have been studied by light and electron microscopy. Rods, single cones and double (twin) cones are present. In the light-adapted state, rods are very tall cells that reach deep into the retinal epithelial (RPE) layer. The long outer segment is composed of discs of uniform diameter displaying one or two incisures. The rod inner segment shows a distal ellipsoid of mitochondria, and then narrows dramatically in the myoid region. Rod nuclei are electron dense and located deep in the outer nuclear layer. Rod synaptic spherules are small and show two to three invaginated synaptic sites as well as superficial synapses. Single cones are similar to the individual members of a double cone and all display a short tapering outer segment, a large ellipsoid of mitochondria and a myoid rich in rough endoplasmic reticulum, polysomes, Golgi zones and autophagic vacuoles. Double cones have extensive subsurface cisternae along their entire contiguous surfaces. Cone nuclei are large and vesicular and located close to or through the external limiting membrane. The synaptic pedicles of cones are larger, more electron lucent, and display more invaginated (ribbon) synapses as well as conventional (superficial) synaptic sites than do the rod spherules. Rod photoreceptors certainly undergo retinomotor movements and it is probable that cones do as well. In the light-adapted state the cone photoreceptors are arranged in a repeating square mosaic pattern with one single cone surrounded by four double (twin) cones.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00185986
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  • 16
    Electronic Resource
    Electronic Resource
    Intraventricular infusion of N-methyl-D-aspartate (1992)
    Springer
    Acta neuropathologica 84 (1992), S. 630-637 
    Details
    ISSN: 1432-0533
    Keywords: Dentrites ; Excitotoxicity ; Glutamate ; N-Methyl-d-aspartate ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary This study documents the ultrastructural features of acute neuronal injury following N-methyl-d-aspartate (NMDA) receptor activation. NMDA (100 nmol/μl) or vehicle was infused over a 15-min period into the lateral ventricle of adult rats. After perfusion fixation, specimens demonstrating normal and abnormal patterns of vascular permeability to horserdish peroxidase were sampled for ultrastructural analysis. In NMDA-infused rats, brain regions exhibiting protein extravasation contained swollen dendritic profiles and abnormal neuronal perikarya. Although periventricular regions were most severely affected, parenchymal abnormalities were also detected in the cerebral cortex, septum, striatum, thalamus, hypothalamus and cerebellum. Mildly affected dendrites contained dark compact mitochondria, while in severely swollen dendrites mitochrondia were enlarged with ruptured cristae. Focal sites of plasma membrane disruption were also detected within swollen dendrites. Swollen neurons commonly displayed peripheral pallor and increased numbers of cytoplasmic vacuoles. Other neurons appeared dark and shrunken, some containing disrupted mitochrondria and pyknotic nuclei. Pretreatment with the NMDA antagonist MK-801 (2 mg/kg) attenuated the neuronal and dendritic alterations. In conditions where cerebrospinal fluid levels of glutamate are abnormally elevated, excessive NMDA receptor activation may lead to early vascular and neuronal complications which could work in concert to promote brain injury.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00227740
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  • 17
    Electronic Resource
    Electronic Resource
    Intraventricular infusion of N-methyl-d-aspartate (1992)
    Springer
    Acta neuropathologica 84 (1992), S. 621-629 
    Details
    ISSN: 1432-0533
    Keywords: Blood-brain barrier ; Endothelium ; Excitotoxicity ; N-Methyl-d-aspartate ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The purpose of this study was to document the early cerebrovascular consequences of excessive N-methyl-d-aspartate (NMDA) receptor activation. Five microliters of NMDA (100 nmol/μl) or vehicle was infused over a 15-min period into the lateral ventricle of adult rats. The protein tracer horseradisch peroxidase (HRP) was injected intravenously for blood-brain bartier (BBB) studies. The intraventricular infusion of vehicle (n=5) caused no alterations in arterial blood pressure or microvascular damage away from the intraventicular probe tract. In contrast, NMDA infusion (n=8) led to a gradual increase in arterial blood pressure (mean 36 mm Hg). Multifocal regions of HRP extravasation were observed bilaterally throughout the neuraxis following NMDA infusion. Sites of BBB disruption and hemorrhage included brain regions bordering ventricular spaces. In addition, isolated foci of protein extravasation were commonly detected in the cerebral cortex, thalamus, basal forebrain, septum and cerebellum. Pretreatment with the noncompetitive NMDA antagonist MK-801 (2 mg/kg) substantially reduced the BBB responses to NMDA. However, microvascular abnormalities were seen in NMDA-infused rats where blood pressure elevations were inhibited by blood removal. In addition to neurons, cerebral blood vessels are also acutely affected by NMDA receptor activation. Blockage of NMDA receptor channels following brain injury may potentially provide protection by attenuating BBB breakdown and subsequent brain edema.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00227739
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  • 18
    Electronic Resource
    Electronic Resource
    Increased iron content in the putamen of patients with striatonigral degeneration (1992)
    Springer
    Acta neuropathologica 84 (1992), S. 328-330 
    Details
    ISSN: 1432-0533
    Keywords: Striatonigral degeneration ; Putaminal pigment ; Iron ; Atomic absorption spectroscopy ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary We measured the total content of iron, cooper, zinc and manganese in the putamen of four patients with striatonigral degeneration (SND) and age-and gender-matched normal controls. The iron content in the SND patients was five times greater than in the controls. Electron microscopic histochemistry revealed the iron reaction products in the pigments showing a triphasic pattern of coarse, electron-dense globules, fine granular and fibrillary materials, and lamellated structures. These findings suggest that increased iron deposition may be related to pigment formation in the putament of SND.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00227827
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  • 19
    Electronic Resource
    Electronic Resource
    Cerebral granular cell tumors: report of a case and a note on their nature and expected behavior (1992)
    Springer
    Acta neuropathologica 84 (1992), S. 680-685 
    Details
    ISSN: 1432-0533
    Keywords: Histiocytic markers ; Astrocytoma ; Electron microscopy ; Glial fibrillary acidic protein ; Granular cell tumor
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary A case of cerebral granular cell tumor (GCT) is reported. Histologically, the growth was composed of benign astrocytes, granular cells and transitional forms between both elements. Glial fibrillary acidic protein was detected in the glial component and, to a lesser extent, in the granular cells. Alpha-1-antichymotrypsin was demonstrated in the latter component only. Ultrastructural study also supported the evidence that neoplastic astrocytes became granular cells. The survey of the literature and our own results suggest that GCTs in this particular location, even when histologically benign, seem to have a worse prognosis than the low-grade supratentorial astrocytomas.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00227746
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  • 20
    Electronic Resource
    Electronic Resource
    Retinal pigment epithelial fine structure in the velvet cichlid (Astronotus ocellatus) (1992)
    Springer
    Anatomy and embryology 186 (1992), S. 371-377 
    Details
    ISSN: 1432-0568
    Keywords: Retinal pigment epithelium (RPE) ; Electron microscopy ; Teleost ; Astronatus ocellatus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The morphology of the retinal pigment epithelium (RPE), choriocapillaris and Bruch's membrane (complexus basalis) have been studied by light and electron microscopy in the velvet cichlid (Astronotus ocellatus). The RPE is composed of a single layer of large columnar cells. The basal (scleral) border of these cells is minimally infolded, whereas the apical (vitreal) surface displays numerous pigment-laden processes which in light-adaptation surround both rod and cone outer segments. Laterally the RPE cells are joined by a series of basally located tight junctions. Wandering phagocytes are a constant feature within this epithelial membrane. The RPE cells display a large, vesicular nucleus, numerous mitochondria, much smooth endoplasmic reticulum, polysomes, myeloid bodies, phagosomes and melanosomes. Rough endoplasmic reticulum is relatively scarce within these cells. Although only light-adapted specimens were examined, it is thought that the melanosomes are capable of extensive retinomotor movement. The endothelium of the choriocapillaris facing Bruch's membrane is typically very thin but shows few fenestrations. Bruch's membrane is typical of other teleost species in that it is composed of only three layers.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00185987
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  • 21
    Electronic Resource
    Electronic Resource
    The cellular network of interstitial cells associated with the deep muscular plexus of the guinea pig small intestine (1992)
    Springer
    Anatomy and embryology 186 (1992), S. 519-527 
    Details
    ISSN: 1432-0568
    Keywords: Intestine ; Interstitial cells ; Innervation ; Electron microscopy ; Guinea pig
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Systematic examination using electron microscopic montages and serial sections has demonstrated that three types of interstitial cell, namely gap junction-rich cells, glycogen-rich cells and fibroblast-like cells, are densely located along the whole extent of the deep muscular plexus of the guinea pig small intestine. They tend to be distributed in an alternating fashion in the cellular network, connected with muscle cells of the outer, circular layer by means of gap junctions. These three types of interstitial cell show close relations to two types of nerve varicosity: one type is characterized by clear round vesicles with diameters of about 50 nm, and the other by flattened vesicles measuring about 35 nm by 70 nm. Electron-dense patches have been observed at the cytoplasmic side of the axonal membranes. Muscle cells of both inner and outer circular layers also show close relations to these two types of nerve varicosity. These morphological features are discussed with the implication that they may have some regulatory role in intestinal movement.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00186974
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  • 22
    Electronic Resource
    Electronic Resource
    Effects of cepharanthine and minoxidil on proliferation, differentiation and keratinization of cultured cells from the murine hair apparatus (1992)
    Springer
    Archives of dermatological research 284 (1992), S. 290-296 
    Details
    ISSN: 1432-069X
    Keywords: Cepharanthine ; Minoxidil ; Culture ; Hair cells ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The effects of cepharanthine and minoxidil on proliferation, differentiation and keratinization of cultured cells from the murine hair apparatus were examined electron microscopically. Both cepharanthine and minoxidil stimulated cell proliferation and delayed initiation of differentiation and keratinization of the cultured cells. On day 6, most control cells (87%) cultured in a 0.03 mM calcium medium without cepharanthine and minoxidil were differentiated into several subpopulations corresponding to those of in vivo cell layers of the hair apparatus, while most of the cells cultured with cepharanthine (71%) or minoxidil (70%) were still immature. On day 13, the number of degenerated cells increased (63%) in the control culture, whereas in the culture treated with cepharanthine or minoxidil, cell degeneration scarcely occurred (5% and 8%, respectively). Differentiated cells having tonofilaments were often observed in the cepharanthine- and minoxidil-treated cultures (76% and 72%, respectively). Elevation of extracellular calcium up to 1.0 mM induced keratinization (34%) in the control culture on day 6, while no keratinized cells were observed in the cepharanthine- or minoxidil-treated culture. On day 13 keratinization similarly occurred in the cultures with cepharanthine (30%) or minoxidil (48%). These results show that both cepharanthine and minoxidil may directly influence proliferation, differentiation and keratinization of cultured cells from the hair apparatus.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00372583
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  • 23
    Electronic Resource
    Electronic Resource
    Ultrastructural localization of actin in normal human skin (1992)
    Springer
    Archives of dermatological research 284 (1992), S. 242-245 
    Details
    ISSN: 1432-069X
    Keywords: Immunogold ; Electron microscopy ; Human skin ; Actin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Normal human skin was embedded in Lowicryl K4M. Actin microfilaments were localized by applyinga postembedding immunogold technique using the monoclonal anti-actin antibody HHF35. Actin microfilaments are part of the cytoskeleton in muscle and nonmuscle cells. Together with myosin they produce contraction. The antibody labelled myofilaments in smooth muscle arrector pili cells, myoepithelial cells and pericytes. In sweat gland cells the microvilli system, a zone beneath the cytoplasma membrane correponding to the adhesion belt region, and apocrine decapitation formations showed labelling.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00375802
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  • 24
    Electronic Resource
    Electronic Resource
    Basal lamina-like material and hemidesmosome-like structures associated with dermal papilla cells in the normal human anagen hair follicle (1992)
    Springer
    Archives of dermatological research 284 (1992), S. 303-306 
    Details
    ISSN: 1432-069X
    Keywords: Hair follicle ; Basal lamina ; Dermal papilla cells ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00372585
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  • 25
    Electronic Resource
    Electronic Resource
    Electron-microscopic description of accretions occurring on tips of infected and non-infected central venous catheters (1992)
    Springer
    Intensive care medicine 18 (1992), S. 464-468 
    Details
    ISSN: 1432-1238
    Keywords: Catheter ; Electron microscopy ; Infection ; Adherence ; Candida albicans
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Objective The purpose of the study was do describe the architecture of accretions occurring on the tips of central venous catheters (CVC). Design A conservative procedure was used followed by two different techniques of electron microscopy Setting and patients the study included 19 catheters which have been used on intensive cared adults, and which were chosen among those of parallel 300 CVC study. Measurements and results CVC were considered sterile, contaminated, colonized or infected according to microbiological and clinical criteria. CVC were found to remain much cleaner than in past clescriptions. When present, accretions were located on the olive-shaped end, and displayed stratified structures with three types of material: amorphous material, thrombus components and inflammatory cells. Bacteria were not seen, even on culture positive CVC. Candida albicans was found on one CVC in the cytoplasm of ganulocytes, and made xio direct contact with the plastic surface. Conclusion This technique should contribute to the understanding of the pathobiology of CVC infection and provide information proving or precluding the involvement of microbial adherence to polymers in vivo.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01708582
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  • 26
    Electronic Resource
    Electronic Resource
    Calcium binding protein (calbindin D28k) immunoreactivity in the hamster superior colliculus: ultrastructure and lack of co-localization with GABA (1992)
    Springer
    Experimental brain research 89 (1992), S. 115-124 
    Details
    ISSN: 1432-1106
    Keywords: Immunocytochemistry ; Visual pathways ; Electron microscopy ; Hamster
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The expression of specific calcium binding proteins is being used increasingly as a potential neuroanatomical marker for neurons with similar functions. In this study, the distribution of calbindin D28k in the superior colliculus (SC) of adult hamsters was examined by light and electron microscopy. Calbindin immunoreactivity was prominent in specific regions and laminae of the SC throughout its rostrocaudal extent, and was found to label horizontal, vertical and stellate cell types. In addition, calbindin label highlighted “bridges” of neuronal processes in the intermediate layers. The most frequent calbindin-immunoreactive profiles seen in the electron microscope were dendrites, some of which were post-synaptic to apparent retinal ganglion cell axon terminals. Labelled axons and axon terminals were less frequently encountered. There was considerable overlap between the size distribution of calbindin D28k-immunoreactive neurons and that of GABA-immunoreactive or Nissl stained neurons in the SC. However, using a double fluorescent labelling technique, and examination of the tissue with confocal laser microscopy, no neurons were observed in the hamster SC that showed immunoreactivity for both calbindin and GABA. In this regard, the SC is similar to the mammalian lateral geniculate nucleus and the pretectum, but differs from the neocortex, where calbindin and GABA are colocalized. The demonstration in the SC, as well as other parts of the nervous system, of sub-populations of neurons that contain distinct calcium-binding proteins suggests that these neurons have different functional properties. Correlative studies may clarify the relevance of these cytoplasmic components as cell markers, as well as their different patterns of association with neurotransmitters and peptides.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00229008
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  • 27
    Electronic Resource
    Electronic Resource
    High-pressure freezing of soybean nodules leads to an improved preservation of ultrastructure (1992)
    Springer
    Planta 188 (1992), S. 155-163 
    Details
    ISSN: 1432-2048
    Keywords: Bradyrhizobium ; Electron microscopy ; Glycine (root nodules) ; High-pressure freezing ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract High-pressure freezing of chemically untreated nodules of soybean (Glycine max (L.) Merr.), in sharp contrast to chemical fixation and prefixation, appears to preserve the ultrastructure close to the native state. This is supported by the observation that the peribacteroid membrane of high-pressure-frozen samples is tightly wrapped around the bacteroids, a finding that is fully consistent with the current views on the physiology of oxygen and metabolite transport between plant cytosol and bacteroids. In soybean root nodules, the plant tissue and the enclosed bacteria are so dissimilar that conventional aldehyde-fixation procedures are unable to preserve the overall native ultrastructure. This was demonstrated by high-pressure freezing of nodules that had been pre-fixed in glutaraldehyde at various buffer molalities: no buffer strength tested preserved all ultrastructural aspects that could be seen after high-pressure freezing of chemically untreated nodules.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00216809
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  • 28
    Electronic Resource
    Electronic Resource
    Studies on the hepatotoxicity induced by bis (tributyltin) oxide (1992)
    Springer
    Archives of toxicology 66 (1992), S. 182-187 
    Details
    ISSN: 1432-0738
    Keywords: Bis(tributyltin) oxide ; Liver ; Electron microscopy ; X-ray microanalysis ; Biochemistry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The toxic effects of bis (tributyltin) oxide (TBTO) on the rat liver were studied with an electron microscope and the accumulation sites of tin were determined with an X-ray microanalyzer. The activities of serum enzymes and the concentration of serum bilirubin were also analyzed. Male Wistar rats received an intramuscular injection of 0.5 ml/kg of TBTO. Marked swelling of the mitochondria appeared in the hepatocytes 4 h after injection of TBTO. Cytoplasmic vacuoles, which contained degenerated mitochondria, gradually increased in number in these hepatocytes. This in turn may have caused a decrease in the volume of hepatic cell cords and an enlargement of sinusoids in the entire hepatic lobule. However, fine structures of intrahepatic bile ducts were not altered. By X-ray microanalysis, tin peaks were preferentially obtained from swollen mitochondria of the hepatocytes. By polarographic analysis of the respiratory responses of mitochondria, it was demonstrated that rates of state 4 respiration and respiratory control ratio were significantly disturbed in TBTO-treated rats in comparison with those of controls. The activities of AST (aspartate aminotransferase) and ALT (alanine aminotransferase) were significantly increased after TBTO treatment, but those of ALP (alkaline phosphatase), LAP (leucine aminopeptidase) and total bilirubin were not changed. These results indicated that parenterally administered TBTO accumulated in the liver cell mitochondria and disturbed oxidative phosphorylation. Mitochondrial dysfunction might induce severe damage of the hepatocytes. Four days after injection of TBTO, hepatic structures and chemical indices were almost restored by the regeneration of hepatocytes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01974012
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  • 29
    Electronic Resource
    Electronic Resource
    Dynamics of PhiX174 protein E-mediated lysis of Escherichia coli (1992)
    Springer
    Archives of microbiology 157 (1992), S. 381-388 
    Details
    ISSN: 1432-072X
    Keywords: PhiX174 ; Bacterial lysis ; Escherichia coli ; Electron microscopy ; Membranes ; Cell envelope
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Expression of cloned gene E of bacteriophage PhiX174 induces lysis by formation of a transmembrane tunnel structure in the cell envelope of Escherichia coli. Ultrastructural studies of the location of the lysis tunnel indicate that it is preferentially located at the septum or at polar regions of the cell. Furthermore, the diameter and shape of individual tunnel structures vary greatly indicating that its structure is not rigid. Apparently, the contours of individual lysis tunnels are determined by enlarged meshes in the peptidoglycan net and the force produced at its orifice, by the outflow of cytoplasmic content. Once the tunnel is formed the driving force for the lysis process is the osmotic pressure difference between cytoplasm and medium. During the lysis process areas of the cytoplasmic membrane which are not tightly attached to the envelope are extended inward by the negative pressure produced during lysis. After cell lysis external medium can diffuse through the lysis tunnel filling the inner cell space of the still rigid bacterial ghosts.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00248685
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  • 30
    Electronic Resource
    Electronic Resource
    Age-related immunoreactivity pattern in medulloblastoma (1992)
    Springer
    Child's nervous system 8 (1992), S. 326-331 
    Details
    ISSN: 1433-0350
    Keywords: Medulloblastomas ; Immunohistochemistry ; Cytokeratins ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Thirty-five paraffin-embedded medulloblastomas (19 from children and 16 from adults; 24 classic medulloblastomas, 10 desmoplastic medulloblastomas, 1 tumor with neuronal differentiation) were examined for reactions with antibodies against glial fibrillary acidic protein (GFAP), cytokeratins KL1 and MNF116, desmin, and vimentin. Only the tumor from the youngest patient, a 152-day-old boy, showed a positive immunoreaction for cytokeratins. Because of this age-related expression of cytokeratins in medulloblastomas primarily in very young children, cytokeratin positivity was interpreted as a sign of tumor immaturity. Five medulloblastomas showed scattered GFAP-positive reactive astrocytes and/or other positive, probably neoplastic, cells. Only two tumors showed GFAP immunoreactivity in unequivocally neoplastic cells. Of six tumors that reacted with vimentin, three showed strong reactivity throughout, one being the tumor from the 152-day-old boy. The remaining three demonstrated nests of vimentin-positive cells with weak or intense somatic immunoreactivity for vimentin. None of the 35 cases showed positivity for desmin, indicating that mesenchymal differentiation is restricted to the rare so-called medullomyoblastomas.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00296563
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  • 31
    Electronic Resource
    Electronic Resource
    The human placental transferrin receptor: Reconstitution into liposomes and electron microscopy (1992)
    Springer
    Bioscience reports 12 (1992), S. 471-482 
    Details
    ISSN: 1573-4935
    Keywords: Transferrin ; Receptor ; Isolation ; Reconstitution ; Liposomes ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Human transferrin receptor was isolated from Triton X-100 solubilized placental plasma membranes by a rapid one-step chromatographic procedure based on immunoadsorption of the receptortransferrin complex on anti-transferrin Sepharose and lectin-affinity on wheat germ agglutinin. Following exchange of Triton X-100 with CHAPS or n-octylglucoside, the purified receptor was incorporated into egg phosphatidylcholine liposomes upon, detergent removal by dialysis (lipid/protein ratio 15:1 to 45:1 (w/w) Reconstitution of the receptor was confirmed by trypsin cleavage to dissociate the large extracellular receptor domain from the liposomal membranes. Electron micrographs of the receptor-lipid recombinants negatively stained with sodium sillicotungstate, showed ographs of the receptor-lipid recombinants negatively stained with sodium sillicotungstate, showed that the receptor molecules distributed very inhomogeneously on the liposomes, most receptors being clustered. Single copies of the receptor were seen as elongate structures (5×10 nm) oriented with their long axis parallel to the liposome surface and separated from this by a 2–3 nm gap. This result provides evidence for a narrow connecting link between the globular extracellular receptor domain and the membrane spanning segment.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01122035
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  • 32
    Electronic Resource
    Electronic Resource
    Exo-endocytosis in isolated peptidergic nerve terminals occurs in the sub-second range (1992)
    Springer
    Bioscience reports 12 (1992), S. 495-501 
    Details
    ISSN: 1573-4935
    Keywords: Electron microscopy ; secretion ; neuropeptides ; exocytosis ; endocytosis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Exo- and endocytotic processes induced by depolarization of isolated neurosecretory nerve terminals show a close temporal correlation, which suggests a short time of integration of the neurosecretory granule membrane with the plasma membrane. In order to determine minimal time requirements for exocytosis-coupled endocytosis to occur, we have analyzed by electron microscopy uptake of horserdish peroxidase (HRP) as a fluid phase marker at the onset of depolarization. We have applied rapid mixing and sampling (quenched flow) to assess events in subsecond time peroids after stimulation. A significant number of labelled endocytotic vacuoles was observed during the first second of depolarization. This number then further increased by a factor of about 2 (within 5 s) and 4 (within 50s). Thus, as for exocytosis, the rate of endocytosis decreased considerably during prolonged stimulation. These data indicate i) that a substantial proportion of secretory granules undergoes exocytosis very shortly after stimulation, and ii) that, following exocytosis, the minimal time required for consecutive membrane retrieval is in the sub-second range.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01122037
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  • 33
    Electronic Resource
    Electronic Resource
    Effect of haloperidol and clozapine on the density of “perforated” synapses in caudate, nucleus accumbens, and medial prefrontal cortex (1992)
    Springer
    Psychopharmacology 106 (1992), S. 45-52 
    Details
    ISSN: 1432-2072
    Keywords: Haloperidol ; Clozapine ; Perforated synapses ; Electron microscopy ; Tardive dyskinesia ; Extrapyramidal syndrome
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Perforated synapses, which contain a discontinuous density along the postsynaptic membrane, can increase or decrease in numbers following various behavioral and biochemical manipulations. We have previously established that 14-day treatment with haloperidol causes an increase in the number of perforated synapses within the caudate nucleus (dorsolateral region) but not the nucleus accumbens (Meshul and Casey 1989). This effect was reversed if the animals were withdrawn from the drug for an equivalent period of time. We have now further examined the effects of haloperidol administration, which is associated with a high incidence of extrapyramidal side effects (EPS) and tardive dyskinesia (TD), and assessed the effects of clozapine, which appears to have a lower potential for inducing EPS and TD. Administration of haloperidol for 2 weeks significantly increased the percentage of perforated synapses in the caudate, but not in the nucleus accumbens or layer VI of medial prefrontal cortex (MPCx). There was an increase in specific [125I]epidepride binding to D-2 receptors in the caudate nucleus and MPCx following haloperidol. Administration of clozapine for 2 weeks did not affect the percentage of perforated synapses in any of the three dopamine (DA)-rich regions that were examined. There was an increase in specific [3H]SCH 23390 binding to D-1 receptors and in specific [125I]epidepride binding to D-2 receptors only within MPCx following clozapine. The absence of any change in the density of perforated synapses within the dorsolateral caudate nucleus following clozapine correlates with: 1) the lack of effect on specific DA receptor binding or down regulation of serotonin (5-HT2) receptors (as reported by others), or 2) the inability in clozapine-treated animals to depolarize block substantia nigra (A9) DA neurons. These results may be related to the low incidence of EPS and TD observed with clozapine.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02253587
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  • 34
    Electronic Resource
    Electronic Resource
    The metathoracic wing-hinge chordotonal organ of an atympanate moth, Actias luna (Lepidoptera, Saturniidae): a light- and electron-microscopic study (1992)
    Springer
    Cell & tissue research 267 (1992), S. 455-471 
    Details
    ISSN: 1432-0878
    Keywords: Chordotonal organ ; Scolopidium ; Homology ; Electron microscopy ; Sensilla ; Evolution ; Actias luna (Insecta)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The structure of a simple chordotonal organ, the presumed homologue of the noctuoid moth tympanal organ, is described in the atympanate moth, Actias luna. The organ consists of a proximal scolopidial region and a distal strand, which attaches peripherally to the membranous cuticle ventral to the hindwing alula. The strand is composed of elongate, microtubule-rich cells encased in an extracellular connective tissue sheath. The scolopidial region houses three mononematic, monodynal scolopidia, each comprised of a sensory cell, scolopale cell, and attachment cell. The dendritic apex is octagonally shaped in transverse section, its inner membrane lined by a laminated structure reminiscent of the noctuoid tympanal organ ‘collar’. A 9+0-type cilium emerges from the dendritic apex, passes through both the scolopale lumen and cap, and terminates in an extracellular space distal to the latter. Proximal extensions of the attachment cell and distal prolongations of the scolopale cell surrounding the cap are joined by an elaborate desmosome, with which is associated an extensive electron-dense fibrillar plaque. Within the scolopale cell, this plaque constitutes the scolopale ‘rod’ material. The data are discussed in terms of both the organ's potential function, and its significance as the evolutionary proto-type of the noctuoid moth ear.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00319368
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  • 35
    Electronic Resource
    Electronic Resource
    Synaptic contacts of tyrosine hydroxylase-immunoreactive elements in the inner plexiform layer of the retina of Bufo marinus (1992)
    Springer
    Cell & tissue research 267 (1992), S. 525-534 
    Details
    ISSN: 1432-0878
    Keywords: Retina ; Dopaminergic neurons ; Synapses ; Inner plexiform layer ; Immunocytochemistry ; Electron microscopy ; Bufo marinus (Anura)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Tyrosine hydroxylase (TH) immunocytochemistry was utilized to quantify dopaminergic synapses in the inner plexiform layer of the retina of Bufo marinus. Since dopaminergic cells have bistratified dendritic arborisation in the inner plexiform layer, attention was given to the segregation of synapses between the scleral and the vitreal sublaminae. Light-microscopically, a more elaborate dendritic branching was observed in the scleral than in the vitreal sublamina. In contrast, about 55% of synapses occurred in the vitreal one fifth of the inner plexiform layer, 30% in the scleral fifth, and 15% in the intermediate laminae. Input sources and output targets showed only minor quantitative differences between sublaminae 1 and 5. TH-immunoreactive processes were found in presynaptic (62.8%) and postsynaptic (37.2%) positions. Synapses to the stained dendrites derived from bipolar (40.4%) and amacrine (59.6%) cells, whereas outputs from the TH-positive processes were directed to amacrine cells (56.8%) and to small and medium-sized dendrites (35.4%); at least some of these can be considered as ganglion cell dendrites. TH-positive profiles neither formed synapses with each other nor were presynaptic to bipolar cell terminals. Junctional appositions of the immunoreactive profiles were occasionally seen on non-stained amacrine and ganglion cell dendrites in the scleral sublamina of the inner plexiform layer and on optic axons in the optic fibre layer. Although dopaminergic cells are mainly involved in amacrine-amacrine interactions, inputs from bipolar terminals and outputs to ganglion cell dendrites were also substantial, suggestive of a role also in vertical information processing.
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    URL: http://dx.doi.org/10.1007/BF00319375
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  • 36
    Electronic Resource
    Electronic Resource
    Cellular differences in the regeneration of murine skeletal muscle: a quantitative histological study in SJL/J and BALB/c mice (1992)
    Springer
    Cell & tissue research 269 (1992), S. 159-166 
    Details
    ISSN: 1432-0878
    Keywords: Regeneration ; Skeletal muscle ; Injury ; Autoradiography ; Morphometry ; Electron microscopy ; Mouse (SJL/J BALB/c)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Skeletal muscle regeneration in SJL/J and BALB/c mice subjected to identical crush injuries is markedly different: in SJL/J mice myotubes almost completely replace damaged myofibres, whereas BALB/c mice develop fibrotic scar tissue and few myotubes. To determine the cellular changes which contribute to these differential responses to injury, samples of crushed tibialis anterior muscles taken from SJL/J and BALB/c mice between 1 and 10 days after injury were analysed by light and electron microscopy, and by autoradiography. Longitudinal muscle sections revealed about a 2-fold greater total mononuclear cell density in SJL/J than BALB/c mice at 2 to 3 days after injury. Electron micrographs identified a similar proportion of cell types at 3 days after injury. Autoradiographic studies showed that the proportions of replicating mononuclear cells in both strains were similar: therefore greater absolute numbers of cells (including muscle precursors and macrophages) were proliferating in SJL/J muscle. Removal of necrotic muscle debris in SJL/J mice was rapid and extensive, and by 6 to 8 days multinucleated myotubes occupied a large part of the lesion. By contrast, phagocytosis was less effective in BALB/c mice, myotube formation was minimal, and fibrotic tissue conspicuous. These data indicate that the increased mononuclear cell density, more efficient removal of necrotic muscle, together with a greater capacity for myotube formation in SJL/J mice, contribute to the more successful muscle regeneration seen after injury.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00384736
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  • 37
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    Electronic Resource
    Differential localization of leu-enkephalin and hyperglycemic hormone in axon terminals of the sinus gland of the crabsCarcinus maenas, eriocheir sinensis, andUca pugilator (1992)
    Springer
    Cell & tissue research 270 (1992), S. 521-526 
    Details
    ISSN: 1432-0878
    Keywords: Enkephalins ; Neuropeptides ; Neurohemal organ ; Immunogold ; Electron microscopy ; Carcinus maenas, Uca pugilator, Eriocheir sinensis (Crustacea)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Leu-enkephalin containing secretory granules were demonstrated in axon terminals of immunogoldlabeled electron-microscopic sections of the sinus gland of three brachyuran crustaceans. These granules have a diameter of 120+-15 nm and differ in electron density from those located in adjacent terminals containing hyperglycemic or molt-inhibiting hormone. These neurohormones do not show co-localization with leu-enkephalin. The cross-reactivity of leu-enkephalin antiserum with met-enkephalin is less than 1%. The sinus glands of the three species examined show no immunoreactivity for FMRF-amide. A modulatory activity of endogenous enkephalin by paracrine mechanisms is suggested.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00645054
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  • 38
    Electronic Resource
    Electronic Resource
    Immuno-electron-microscopic localization of basic fibroblast growth factor in the dystrophic mdx mouse masseter muscle (1992)
    Springer
    Cell & tissue research 270 (1992), S. 569-576 
    Details
    ISSN: 1432-0878
    Keywords: Basic fibroblast growth factor ; Regeneration ; Degeneration ; Immunohistochemistry ; Electron microscopy ; Masseter muscle ; Myoneural junction ; Mouse (dystrophic mdx)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The localization of basic fibroblast growth factor (bFGF)-like immunoreactivity in the masseter muscle of dystrophic mdx mice on postnatal day 28 was investigated by immunoblot analysis and electron microscopy. Crude homogenate of the masseter muscle, when subjected to immunoblotting with a bFGF antiserum, exhibited a main band with the same molecular weight (18 kDa) as bovine bFGF. By electron microscopy, bFGF immunoreactivity was detected in small regenerating myocytes; the smaller cells were the premature myocytes, the most intense staining was the immunoreactivity within the cytoplasm. Putative precursors of the muscle cells with a few myofilaments, which were most intensely labeled with anti-bFGF, contacted each other and possibly developed into multinucleated myocytes through cell fusion. Mature myocytes with densely packed myofilaments and peripherally located nuclei did not exhibit bFGF immunoreactivity; they formed myoneural junctions with motor nerve endings immunoreactive for bFGF. Early differentiating myocytes with intense bFGF-like immunoreactivity did not make contact with immunoreactive nerve terminals. Degenerating large myocytes with a limited number of distorted and/or disrupted myofilaments exhibited electron-dense deposits in the cristae of mitochondria; these deposits were not abolished by immunoadsorption control experiments. Thus, the cell-size-dependent decrease in bFGF immunoreactivity in regenerating but not in degenerating myocytes provides a morphological basis for an autoregulatory role of bFGF in muscle regeneration. This study suggests that neuronal bFGF is not involved in initial muscle regeneration in the dystrophic mdx mouse.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00645060
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  • 39
    Electronic Resource
    Electronic Resource
    Ovarian innervation develops before initiation of folliculogenesis in the rat (1992)
    Springer
    Cell & tissue research 270 (1992), S. 87-93 
    Details
    ISSN: 1432-0878
    Keywords: Ovarian nerves ; Development ; Folliculogenesis ; Tyrosine hydroxylase ; Immunohistochemistry ; Electron microscopy ; Rat (Sprague Dawley)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Sympathetic neurotransmitters have been shown to be present in the ovary of the rat during early postnatal development and to affect steroidogenesis before the ovary becomes responsive to gonadotropins, and before the first primordial follicles are formed. This study was undertaken to determine if development of the ovarian innervation is an event that antedates the initiation of folliculogenesis in the rat, Rattus norvegicus. Serial sections of postnatal ovaries revealed a negligible frequency of follicles 24 h after birth (about 1 primordial follicle per ovary). Twelve hours later there were about 500 follicles per ovary, a number that more than doubled to about 1300 during the subsequent 12 h, indicating that an explosive period of follicular differentiation occurs between the end of postnatal days 1 and 2. Electron microscopy demonstrated that before birth the ovaries are already innervated by fibers containing clear and dense-core vesicles. Immunohistochemistry performed on either fetal (day 19) or newborn (less than 15h after birth) ovaries showed the presence of catecholaminergic nerves, identified by their content of immunoreactive tyrosine hydroxylase (TH), the rate-limiting enzyme in catecholamine biosynthesis. While some of these fibers innervate blood vessels, others are associated with primordial ovarian cells, thereby suggesting their participation in non-vascular functions. Since prefollicular ovaries are insensitive to gonadotropins, the results suggest that the developing ovary becomes subjected to direct neurogenic influences before it acquires responsiveness to gonadotropins.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00381883
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  • 40
    Electronic Resource
    Electronic Resource
    The effects of ageing on the morphology and function of the zonae fasciculata and reticularis of the rat adrenal cortex (1992)
    Springer
    Cell & tissue research 270 (1992), S. 265-272 
    Details
    ISSN: 1432-0878
    Keywords: Adrenal cortex ; Ageing ; Steroidogenesis ; Electron microscopy ; Morphometry ; Rat (Wistar)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The morphological counterpart of the well-known age-dependent marked impairment of glucocorticoid secretion of rat adrenals was investigated by use of morphometric techniques. For this purpose 4-, 8-, 16- and 24-month-old rats were studied. Despite the notable lowering of both basal and ACTH-stimulated production of corticosterone by collagenase-dispersed inner adrenocortical cells, ACTH and corticosterone plasma concentrations displayed significant increases with ageing. Zona fasciculata (ZF) and zona reticularis (ZR) showed a notable hypertrophy in aged rats, which was due to rises in both the average volume and number of their parenchymal cells. The hypertrophy of ZF and ZR cells was in turn associated with increase in the volume of the mitochondrial compartment and proliferation of smooth endoplasmic reticulum, i.e., the two organelles involved in steroid-hormone synthesis. All these morphologic changes, conceivably due to the chronic exposure to high levels of circulating ACTH, are interpreted as a response enabling ZF and ZR to compensate for their age-dependent lowering in glucocorticoid secretion. Stereology also demonstrated that ZF and ZR cells underwent a striking age-related lipid-droplet repletion. Lipid droplets are the intracellular stores of cholesterol esters, the obligate precursors of steroid hormones in rats. This finding is in keeping with the contention that the mechanism underlying the age-dependent decline in rat-adrenal glucocorticoid secretion mainly involves impairments of the utilization of intracellular cholesterol previous to its intramitochondrial transformation to pregnenolone.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00328012
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  • 41
    Electronic Resource
    Electronic Resource
    Characterization of macrophage-like cells in the external layers of human small and large intestine (1992)
    Springer
    Cell & tissue research 270 (1992), S. 273-279 
    Details
    ISSN: 1432-0878
    Keywords: Macrophages ; Small intestine ; Large intestine ; External muscle layer ; Immunohistochemistry ; Histochemistry ; Electron microscopy ; Man
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary In the external layers of human small and large intestine macrophage-like cells were characterized by immunohistochemical, histochemical and electronmicroscopical methods. Using immunohistochemistry and a number of monoclonal antibodies, the presence and distribution of phenotypic subpopulations of macrophages were evaluated. In all locations macrophage-like cells were identified with antibody EBM11, which recognizes CD68 antigen, C3bi which recognizes CD11b, and partly with an antibody which recognizes protein 150,95 (CD11c). Macrophage-like cells in the external muscle layer were HLA-DR-positive (expressing the MHC class-II antigen), in contrast to macrophage-like cells in the subserosa and submucosa. Macrophage-like cells in the external muscle layer were mostly acid phosphatase-negative, and at the electron-microscopic level they were found to have features of macrophages: primary lysosomes, coated vesicles and pits. However, very few secondary lysosomes were present. Birbeck granules were not observed. It is concluded that in the external muscle layer of human small and large intestine numerous macrophages of a special type are present. It is discussed whether this cell type plays a role in gastrointestinal motility and/or has an immunological function.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00328013
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  • 42
    Electronic Resource
    Electronic Resource
    Initial formation of cellular intrinsic fiber cementum in developing human teeth (1992)
    Springer
    Cell & tissue research 267 (1992), S. 321-335 
    Details
    ISSN: 1432-0878
    Keywords: Teeth ; Cementum ; Cementoblasts ; Matrix production ; Electron microscopy ; Human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The present study describes the formative process of the initiation of cellular intrinsic fiber cementum (CIFC) in still growing human teeth. From 29 premolars and molars with incomplete roots developed to 60–90% of their final length, 8 premolars (with roots formed to three quarters of their final length) were selected for electron-microscopic investigation. All teeth were clinically intact and prefixed in Karnovsky's fixative immediately after extraction. Most of them were decalcified in ethylene diaminetetraacetic acid (EDTA), and the apical part of the roots was divided axially into mesial and distal portions that were subdivided in about 5 slices each. Following osmication and embedding in Epon, these blocks were cut for light- and electron-microscopic examination. In addition, 5 teeth with incomplete roots were freed from organic material and processed for scanning electron microscopy. It was found that CIFC-initiation commenced very close to the advancing root edge and resulted in a rapid cementum thickening. Thereafter, appositional growth continued on the already established cementum surface. Large, basophilic and rough endoplasmic reticulum-rich cementoblasts, some of which became cementocytes, were responsible for both fast and slow CIFC-formation. The CIFC-matrix was free of Sharpey's fibers and composed of more or less organized intrinsic collagen fibrils, in part fibril bundles, that ran roughly parallel to the root surface. Initially, the cementum fibrils intermingled with those of the dentinal collagen fibrils, which were not yet mineralized. This boundary subsequently underwent calcification. The development of collagen fibril bundles and their extracellular arrangement were associated with cytoplasmic processes probably involved in fibril formation and fibril assembly. Many cementoblasts contained intracytoplasmic, membrane-bounded collagen fibrils, which probably were related to fibril formation rather than degradation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00302971
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  • 43
    Electronic Resource
    Electronic Resource
    Development of cytoplasmic digitations between Leydig cells and testicular macrophages of the rat (1992)
    Springer
    Cell & tissue research 267 (1992), S. 385-389 
    Details
    ISSN: 1432-0878
    Keywords: Leydig cells ; Macrophages ; Development, ontogenic ; Electron microscopy ; Testis ; (Rat Wistar)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Testicular macrophages and Leydig cells from adult animals are known to be functionally coupled. For example, secreted products from macrophages stimulate testosterone secretion by Leydig cells. In adult rat testes, structural coupling also exists between these cells. This coupling consists of cytoplasmic projections from Leydig cells located within cytoplasmic invaginations of macrophages. Although macrophages are known to exist in the testis in immature animals, it is not known when these digitations develop. The purpose of the present study was to determine whether the time of their development coincides with known maturational events that occur in Leydig cells, particularly during the peripubertal period. Testes from rats at 20, 30 and 40-days-of-age as well as testes from mature rats weighing more than 500 gm were prepared for ultrastructural analysis. It was found that digitations form between 20 and 30-days-of-age. These structures varied from simple tubular projections to complicated branched structures, suggesting that digitations are more than simple invaginations of microvilli into coated vesicles as previously described. Subplasmalemmal linear densities were also observed within macrophages juxtaposed to Leydig cells. Collagen was commonly observed between macrophages and Leydig cells in animals 20 days old. These studies demonstrate that although macrophages are present in the testis in maximal numbers at 20 days-of-age, they do not form junctions with Leydig cells until day 30. This is just prior to the major increase in secretory activity of rat Leydig cells that occurs during puberty.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00302977
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  • 44
    Electronic Resource
    Electronic Resource
    Interstitial cells associated with the deep muscular plexus of the guinea-pig small intestine, with special reference to the interstitial cells of Cajal (1992)
    Springer
    Cell & tissue research 268 (1992), S. 205-216 
    Details
    ISSN: 1432-0878
    Keywords: Intestine ; Interstitial cells ; Pacemaker ; Electron microscopy ; Guinea-pig
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Interstitial cells associated with the deep muscular plexus of the guinea-pig small intestine were studied by electron microscopy, and three-dimensional cell models were reconstructed from serial ultrathin sections with a computer graphic system. Three types of cells were recognized. The first type was similar in shape to smooth muscle cells, but did not contain an organized contractile apparatus. Many large gap junctions comprising about 4% of the cell surface were present; they connected cells of the first type to each other, to the second type of cell and to smooth muscle cells of the outer circular layer. The second type of cell had a welldemarcated cell body with long slender processes and was characterized by a large amount of glycogen comprising about 9% of the cell volume. The third type of cell was similar to fibroblasts, and contained well-developed Golgi apparatus and rough endoplasmic retiulum. Some of these fibroblast-like cells (a possible subtype) formed small gap junctions. All three types of cells showed close relationships with nerve varicosities. This cellular network consisting of gap-junction-rich cells, glycogen-rich cells and smooth muscle cells may be involved in the pacemaking activity of intestinal movement.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00318788
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  • 45
    Electronic Resource
    Electronic Resource
    12-O-tetradecanoylphorbol-13-acetate induces selective desquamation of superficial cells in rat urinary bladder epithelium (1992)
    Springer
    Cell & tissue research 268 (1992), S. 239-245 
    Details
    ISSN: 1432-0878
    Keywords: Urinary bladder ; Epithelial desquamation ; TPA ; Electron microscopy ; Rat (Donryu)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary 12-O-tetradecanoylphorbol-13-acetate (TPA) is known to affect the proliferation and/or differentiation of several types of cells. We injected TPA directly into the lumen of rat bladder to determine, using scanning and transmission electron microscopy, its effects on the bladder epithelium in vivo. At 1 h after TPA injection (1μg/ml), the superficial cells of the epithelium had changed their morphology, and large spherical vacuoles occupied their cytoplasm. In some areas, the underlying intermediate cells were exposed by the desquamation of the superficial cells. During the next few hours, TPA was excreted from the bladder lumen by voluntary micturition, but the desquamation of the superficial cells proceeded further. All the superficial cells were lost from the luminal surface by 24 h after TPA injection. The changes noted were specific for the superficial cells and were not observed in the intermediate or basal cells. After 24h, part of the epithelium had a three-layer structure, indicating that regeneration was taking place. These results demonstrate that TPA selectively affects and desquamates superficial cells in a short period of time. This experimental system may be useful for studying in vivo cell proliferation and/or differentiation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00318792
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  • 46
    Electronic Resource
    Electronic Resource
    Histochemical localization of nucleoside triphosphatase activity in assimilate conducting plant tissue (1992)
    Springer
    Protoplasma 167 (1992), S. 145-151 
    Details
    ISSN: 1615-6102
    Keywords: ATPase ; UTPase ; Electron microscopy ; Energy-dispersive X-ray microanalysis ; Gomphrena globosa ; Histochemistry ; Hordeum distichon ; Monstera deliciosa ; Phloem
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary For the histochemical localization of nucleoside triphosphatases at the electron microscopic level, prefixed tissues were incubated with lead nitrate in addition to substrate (GOMORI reaction). While ATP and UTP as substrates gave electron-dense reaction products at the plasmalemma of sieve tubes, companion cells and phloem parenchyma cells, and at plasmodesmata in primary pitfields, AMP gave reaction products only at the tonoplast of parenchyma cells. Since electron-dense deposits also occur in cell walls and vacuoles, energy dispersive X-ray microanalysis was used to distinguish between lead deposits and lead-phosphate deposits. The latter were restricted to the symplast. Among the three plant species used, the leaf bundle phloem ofHordeum distichon showed ATPase activity largely restricted to the phloem cells, except for the thickwalled sieve tubes. Some activity also bordered the chloroplasts of the bundle sheath cells. In the C4 plantGomphrena globosa, ATPase and UTPase activities appeared to be the greater in phloem parenchyma cells than in sieve tubes. In the phloem of youngMonstera deliciosa roots, ATPase occurred not only at the plasmalemma of sieve tubes, but also around sieve-tube plastids. When compared with AMP as substrate, it appears that nucleoside triphosphates are the natural substrates of the enzyme(s) in the plasmalemma of sieve tubes and phloem parenchyma cells.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01403377
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  • 47
    Electronic Resource
    Electronic Resource
    Effects of organic acids on stria vascularis ultrastructure and function in the chinchilla (1992)
    Springer
    European archives of oto-rhino-laryngology and head & neck 249 (1992), S. 168-171 
    Details
    ISSN: 1434-4726
    Keywords: Cochlea-Stria vascularis ; Electron microscopy ; Endocochlear potential ; Loop diuretics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The purpose of this study was to compare the effects of several organic acids (probenecid, sodium salicylate and penicillin G) on the endocochlear potential (EP) and the ultrastructure of the stria vascularis of the chinchilla with the effects of furosemide on these parameters. chinchillas received 50 mg/kg i.v. doses of probenecid, sodium salicylate or penicillin G, or 25 mg/kg i.v. furosemide. The EP was monitored continuously before and for 60 min afterwards. The stria vascularis was removed at 10-min intervals from animals and from 10 to 60 min after the injection of these agents. Specimens were then processed for transmission electron microscopy. Only furosemide had an effect on the EP, causing a reversible reduction. The reduction of the EP was accompanied by the appearance of edema in the intercellular spaces of the stria vascularis. No significant edema was found after probenecid, sodium salicylate or penicillin G. This was consistent with the finding that none of these latter three agents affected the endocochlear potential.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00183494
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  • 48
    Electronic Resource
    Electronic Resource
    Muscle pathology in idiopathic cricopharyngeal dysphagia (1992)
    Springer
    European archives of oto-rhino-laryngology and head & neck 249 (1992), S. 216-223 
    Details
    ISSN: 1434-4726
    Keywords: Cricopharyngeal dysphagia ; Muscle biopsy ; Electron microscopy ; Enzyme histochemistry ; Myositis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The structural changes in the cricopharyngeal muscle (CM) were examined ultrastructurally and by enzyme histochemistry in five patients suffering from idiopathic cricopharyngeal dysphagia (ICD). Diagnosis was established by fiberoptic esophagoscopy, esophageal manometry and cineradiography. Cricopharyngeal myotomy was performed with marked improvement in all patients. Intraoperatively, a biopsy was taken from the CM. Additionally, all patients underwent neurological examination for possible generalized muscle disease, and a biopsy was taken from a limb muscle. CM from nine cadavers without known history of dysphagia served as control. The control samples disclosed structural changes which were considered to be pathological in other skeletal muscles, and required that the criteria for CM pathology we modified accordingly. In three patients changes in CM histology suggested specific pathogenesis: one patient had evidence for a generalized myositis but was only symptomatic for dysphagia. Another patient had muscle fiber atrophy and slight inflammation in her CM, possibly due to alcohol abuse. The third patient had loss of CM fibers with replacement by connective tissue enough to cause functional disturbances. In two patients no cause for dysphagia was found in either immunohistochemistry or electron microscopic studies. These results demonstrate the special structural features of the CM and indicate that ICD can have multiple etiologies.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00178473
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  • 49
    Electronic Resource
    Electronic Resource
    Extracellular matrix in the rat spiral limbus (1992)
    Springer
    European archives of oto-rhino-laryngology and head & neck 249 (1992), S. 224-230 
    Details
    ISSN: 1434-4726
    Keywords: Inner ear ; Rat spiral limbus ; Intercellular matrix ; Electron microscopy ; Immunomorphology
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The matrix of the spiral limbus is obviously a special form of the intercellular substance. In the present study, the rat's spiral limbus was investigated by electron microscopy after fixation with ruthenium red and tannic acid and immunofluorescence to demonstrate matrix components. Collagen types I, II, V, VI, VII, IX and XI and fibronectin were not observed. Collagen type II and cartilage-specific proteoglycans, however, occurred in large quantities. The basal lamina of interdental cells and inner sulcus cells did not contain any collagen type IV. while the basal lamina of the capillaries had only minor amounts. Laminin and nidogen appeared in large amounts in the basal lamina. After fixation with tannic acid, the matrix between the interdental cells and the capillaries contained 20- to 22-nm-thick single and irregularly running fibrils as well as plaques of a fine granular material. After fixation with ruthenium red, 30-to 60-nm-thick, electron-dense granules occurred and most probably consisted of proteoglycans. These findings indicate that the composition of the matrix of the spiral limbus is similar to that of cartilage but not identical.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00178474
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  • 50
    Electronic Resource
    Electronic Resource
    Neural and infranuclear region changes in outer hair cells in acoustically exposed rabbits (1992)
    Springer
    European archives of oto-rhino-laryngology and head & neck 249 (1992), S. 287-292 
    Details
    ISSN: 1434-4726
    Keywords: Nerve endings ; Outer hair cells ; Acoustic exposure ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Rabbits were exposed to 100 dB pure-tone sound at 2 kHz for 2 h. Electron microscopy was used to study the relationship between changes in the outer hair cells, afferent nerve endings and efferent nerve endings. There was no relationship found between the degree of changes produced in the afferent nerve endings and that the outer hair cells. However, there was a relationship demonstrable between the degree of changes seen in the efferent nerve endings and the infranuclear region of the outer hair cells. These findings show that acoustic trauma will damage most the infranuclear region of the outer hair cells, while efferent nerve endings are injured next and least affected are afferent nerve endings.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00714495
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  • 51
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    Electronic Resource
    Chromatographic properties of macroporous beads from poly(GMA-co-EDMA) (1992)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 195 (1992), S. 139-150 
    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: Eine Reihe makroporöser Glycidylmethacrylat-Ethylendimethacrylat-Copolymerer (GMA-co-EDMA) wurde durch Suspensionspolymerisation hergestellt; dabei wurden nach einer statistisch geplanten experimentellen Durchführung die Ethylendimethacrylatkonzentration und die Heizrate der Polymerisationstemperatur von 20 auf 70°C variiert. Die Porositätseigenschaften der hydrolysierten Copolymeren wurden mit Hilfe der Größenausschlußchromatographie unter Verwendung von Polystyrolstandards in Tetrahydrofuran charakterisiert. Das Porenvolumen, die spezifische Oberfläche und die Porengröße werden dabei durch die Konzentration des Vernetzungsmittels stärker beEinflußt als durch die Heizrate während der Polymerisation.
    Notes: A series of macroporous glycidyl methacrylate-ethylene dimethacrylate copolymers have been prepared by the suspension polymerization according to a statistical design of experimental approach in which concentration of ethylene dimethacrylate and time needed for raising the polymerization temperature from 20 to 70°C have been varied. The porous properties of hydrolyzed copolymers have been characterized by means of size exclusion chromatography using polystyrene standards in tetrahydrofuran. Pore volume, specific surface area, and pore size are affected by the crosslinking agent concentration rather than by the rate of temperature increase during the polymerization reaction.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1992.051950111
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  • 52
    Electronic Resource
    Electronic Resource
    Synthese und koagulationsverhalten von hydrophilen copolymeren des acrylnitrils (1992)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 195 (1992), S. 171-190 
    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: Copolymers of AN were prepared with variable molecular masses and with variable contents of methylacrylate (ASME) and sodiumallylsulfonate (NaAS), acrylamide (AA), itaconic acid (IS), polyethyleneglycol acrylate (600) (PEGA), vinylacetate (VA), 2-hydroxyethyl acrylate, (HEE) or sodium acrylamido-2-methylpropanesulfonate (NaAMPS), respectively, by using a mathematical model for the calculation of the polymerization conditions needed. Precipitation studies by light scattering showed the predominant influence of NaAS and NaAMPS on the precipitation properties. Acrylonitrile homopolymers show a hard precipitation behaviour. The originating particles have a density of between 0.2 and 0.4 g/cm3. An increasing content of NaAS or NaAMPS leads for example beginning from 0.8 wt.-% NaAS in the monomer composition to a soft precipitation behaviour and to highly swollen particles possessing a density of less than 1 · 10-2 g/cm3. The molar mass and the ASME-content show no significant influence. For the acrylonitrile/acrylamide system already 0.5 wt.-% allylsulfonate is sufficient to get a soft precipitation behaviour with formation of highly swollen particles. All samples with the other cocomponents and without NaAS- or NaAMPS-comonomer show a hard precipitation behaviour with little swollen particles.
    Notes: Copolymere des Acrylnitrils (AN) mit variabler Molmasse bzw. mit variablem Anteil von Acrylsäuremethylester (ASME) und Natriumallylsulfonat (NaAS), Acrylamid (AA), Itaconsäure (IS), Polyethylenglykolacrylat (600) (PEGA), Vinylacetat (VA), Acrylsäure-2-hydroxyethylester (HEE) oder Natrium-2-acrylamido-2-methylpropansulfonat (NaAMPS) wurden hergestellt, wobei die erforderlichen Polymerisations-bedingungen mit Hilfe eines mathematischen Polymerisationsmodells ermittelt wurden.Die Fällungsuntersuchungen mit der Methode der Lichtstreuung zeigten, daß NaAS und NaAMPS einen dominierenden Einfluß haben. Bei Acrylnitril-Homopolymeren tritt eine harte Fällung auf, und die entstehenden Partikel haben eine Dichte zwischen 0,2 und 0,4 g/cm3. Zunehmender NaAS-bzw. NaAMPS-Gehalt führt ab einem Gehalt von beispielsweise ca. 0,8 Gew.-% NaAS im Monomergemisch zu einer weichen Fällung, bei der hochgequollene Partikel mit einer Dichte in der Größenordnung von 〈 1.10-2 g/cm3 entstehen. Ein Einfluß der Molmassen und des ASME-Gehaltes Konnte nicht nachgewiesen werden. Beim Acrylnitril/Acrylamid-System genügen offensichtlich 0,5 Gew.-% Allylsulfonat im Monomeransatz, um eine stabile, weiche Fällung unter Bildung hochgequollener Strukturen zu gewährleisten. Alle Proben mit den übrigen hydrophilen Cokomponenten zeigen ohne NaAS bzw. NaAMPS-Comonomer ein hartes Fäungsverhalten mit wenig gequollenen Partikeln.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1992.051950114
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    Mitteilungen (1992)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 195 (1992), S. 213-213 
    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.1992.051950117
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  • 54
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    Photolytic crosslinking of poly(p-hydroxystyrene) (1992)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 195 (1992), S. 191-204 
    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 Photovernetzung von Poly(p-hydroxystyrol) (PPHS) wird durch O2 beachtlich beschleunigt. Dies ergab sich aus der Bestimmung der Molmasse (mit Hilfe der Lichtstreumethode) und des Gelanteils nach kontinuierlicher Bestrahlung bei λinc = 254 nm. Aufgrund von Ergebnissen aus Blitzphotolyseversuchen wird der folgende Reaktionsmechanismus aufgestellt: Die Vernetzung sowohl in An-als auch Abwesenheit von O2 kommt im wesentlichen durch Kombination von Radikalen des Phenoxyltyps zustande. In Abwesenheit von O2 werden Phenoxylradikale ausschließlich durch Spaltung von O—H-Bindungen phenolischer Gruppen, die sich im angeregten Singulettzustand befinden, erzeugt. Triplett-angeregte phenolische Gruppen, die sich auch bilden, desaktivieren nicht durch Spaltung der O—H-Bindungen. Sie reagieren allerdings sehr effektiv, sofern vorhanden, mit O2. Bei dieser Reaktion entstehen HO·2- und zusätzliche Phenoxylradikale. Alle handelsüblichen und die meisten im Labor synthetisierten PPHS-Proben enthalten chemisch gebundene, chinoidartige Verunreinigungen. Durch Versuche mit niedermolekularen Modellverbindungen wurde nachgewiesen, daß triplett-angeregte chinoide Gruppen einerseits mit phenolischen Gruppen unter Bildung von Phenoxylradikalen reagieren und daß sie andererseits unreaktiv sind bezüglich der Abstraktion aliphatischer Wasserstoffatome. Die Bestrahlung von PPHS bei λinc = 254 nm bewirkt die Bildung chinoider Gruppen, die bei dieser Wellenlänge auch stark absorbieren. Die Lichtabsorption dieser Gruppen wird im Laufe der weiteren Bestrahlung zum bestimmenden Faktor hinsichtlich der photochemischen Veränderung des Polymeren.
    Notes: Light-induced crosslinking of poly(p-hydroxystyrene) (PPHS) is significantly enhanced by O2. This was evidenced by molar mass (light scattering measurements) and by gel content determinations which were performed on various polymer samples before and after continuous irradiation at λinc = 254 nm. The following mechanism was elucidated with the aid of flash photolysis studies: Crosslinking in the absence or presence of O2 is mainly due to the combination of phenoxyl type radicals. In the absence of O2 the latter are exclusively formed by O—H bond cleavage of singlet excited phenolic groups. Triplet excited phenolic groups which are also formed do not deactivate via O—H bond cleavage but react very effectively with O2. This reaction leads to the formation of HO2· and additional phenoxyl type radicals. All Commercial and most laboratory-prepared PPHS samples contain chemically bound impurities of quinoid nature. On the basis of results performed with model compounds of low molar mass, it is concluded that triplet excited quinoid groups react effectively with phenolic groups forming phenoxyl type radicals and that they are quite unreactive with respect to the abstraction of alphatic hydrogen atoms. Irradiation of PPHS at λinc = 254 nm causes the formation of quinoid groups which absorb strongly at this wavelength. Light absorption by these groups becomes a determining factor with respect to photochemical alteration in the course of further irradiation.
    Additional Material: 9 Ill.
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    URL: http://dx.doi.org/10.1002/apmc.1992.051950115
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  • 55
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    Polyacetal/poly(tetrafluoroethylene) blends, I. The effect of Na-treated poly(tetrafluoroethylene) on polyacetal (1992)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 196 (1992), S. 21-35 
    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 verschiedenartigen Eigenschaften von Polymerlegierungen aus Polyoxymethylen (POM) und bis zu 20 Gew.-% chemische oberf;ächenbehandeltem Poly(tetrafluorethylen) (CPTFE) wurden untersucht und denen unbahandelter POM/PTFE- Blends gegenübergestellt. PTFE iwrd POM zugesetzt, um dessen Oberflächenabriebseigenschaften Anteil zunehmend verschlechtert. Durch die bessere Phasenanbindung in den oberflächenbehandelten POM/CPTFE- Blends konnten die doppelten Zugfestigkeiten und EModuli wie bei unbehandelten POM/PTEF- Blends erreicht werden. Mit Hilfe der Elektronenmikroskopie (SEM) konnte gezeigt werden, daß die PTEF-Agglomerate in der POM-Matrix eine Größe von 30 bis 100 μm haben, während die CPTFE-Teilchengrößbe unter 1 μum liegt.
    Notes: The various properties of the blends of polyacetal (POM) with up to 20 wt.-% chemically surface-treated poly(tetrafluoroethylene) (CPTFE) were investigated and compared with those of POM/PTFE blends. The PTFE is added to POM to improve the wear properties, however, the mechanical properties of POM/PTFE blends decrease with increasing PTFE content, but tensile strength and Young's modulus of POM/CPTFE blends are more than 2 times higher than that of the POM/PTFE blends. SEM shows that the size of inherent agglomerative PTFE is in the range of 30 to 100 μm. The particle size of major CPTFE dispersed in POM is smaller than 1 μm.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1992.051960102
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  • 56
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    Synthesis and chemo-physical properties of hydrogels (1992)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 196 (1992), S. 49-61 
    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: Hydrogele wurden aus methylmethacrylat (MMA) and N-Vinyl-2-pyrrolidon (NVP) mit 1,2,2-Trimethylolpropantrimethacrylat (TPTA) als Vernetzungsmittel hergestellt. Die Terplymerisation wurden mittels UV-strahlung (365 nm) initiiert, wobei kleine Mengen an Diethoxycetophenon (DEAP) als Photosensibilisator sowie Triethanolamin(TEA)als Beschleuniger und Verdünner verwendet wurden. Die Hydrogele wurden durch Messung des Wasserrückhaltevermögens, der Sauerstodiffusions- und permitionskoeffizienten, der mechanischen Eigenschaften und der Lichtdurchlässigkeit charakterisiert. Dabei zeigte sich, daß die Hydrogele bis zu 80 Gew.-% Wasser aufnehmen können, wobei mit steigendem Wassergtehalt deren mechanische Festigkeit drastisch sinkt. Der Ssuerstoffdiffusionskoeffizient der gequollenen Hydrogele beträgt 10-6 cm2s-1, der Sauerstoffpermeationskoeffizient 1013 cm2s-1Pa-1, und die Lichtdurchlässigkeit liegt im Bereich von 500 bis 700 nm bei über 90%.
    Notes: Hydrogels are synthesized from methyl methacrylate (MMA) and N-vinyl-2-pyrrolidone (NVP) with 1,1,1-trimethylol propane trimethacrylate (TPTA) as a crosslinking agent. It was polymerized under UV radiation (365nm) with a small amount of photosensitizer, diethoxy acetophenone (DEAP), acclerator and diluent, triethanol amine (TEA). The hydrogels were characterized by measuring the water retention, dissolved oxygen diffusivity and permeability, mechanical strength, and light transparency. The hydrogels can retain water up to 80 wt.-% and the mechanical strenght is weakened as the water content is increased in the gel. The dissolved oxygen diffusivity and permeability in the swelling hydrogels are determined to be 10-6 cm2/sec and 1013 cm2s-1 Pa-1, respectively. The light transparency is over 90% in the wave lenght ranging from 500 to 700 nm.
    Additional Material: 5 Ill.
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    URL: http://dx.doi.org/10.1002/apmc.1992.051960104
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    Synthesis and properties of cationic amine-epoxy adducts and their use in electrodeposition, IIPart I cf. 12.. Diethanolamine/diketimine terminated cationic epoxy resins with pendent 2-ethylhexanol-blocked TDI groups (1992)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 196 (1992), S. 73-87 
    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 Bisphenol-A-Epoxidharz wurde zunächst mit Toluylendiisocyanat, dessen eine Isocyanatgruppe mit 2-Ethylhexanol blockiert war, und dann mit unterschiedlichen Mischungen on Diethanolamin und Bis(2-methyl-isobutylketiminoethyl)amin (DKI)umgesetzt. Aus diesen Harzen mit Triethanolamin- und DKI-Endgruppen wurden durch Hydrolyse und Neutralisieren mit Essigsäure kationische Harze mit primären Amin-Endgruppen erhalten, aus denen mit geeigneten Lösungsmitteln und deionisiertem Wasser Emulsionen hergestellt wurden. Deren Eigenschaften und die Elektroabscheidung der Harze aus den Emulsionen wurden untrsucht. Der Effekt der Zugabe von hydrophoben Lösungsmitteln wie Toluol oder Hexylcellosolv (HCS) auf die Abscheidungseigenschaften wird diskutiert.
    Notes: A diglycidylether of bisphenol A epoxy resin (DGEBA) was first reacted with 2,4-toluene diisocyanate partially blocked with 2-ethylhexanol (2-EH P. B. TDI) to form modified epoxy resins, and subsequently reacted with different molar ratios of diethanolamine and bis(2-methylisobutylketiminoethyl)amine (DKI) (used as ring opening agents) to give diethanolamine/diketimine terminated resins. These resins were hydrolyzed and neutralized with acetic acid to give cationic resins containing various contents of primary amine groups in the terminal polymeric chain. These cationic resins can be dissolved in a suitable solvent and mixed with deionized water to obtain emulsions. The electrodeposition properties and characteristics of the resulting cationic resins were investigated in detail. The effects of hydrophobic solvents, such as hexyl cellosolve (HCS) and toluene, on the deposition properties of the emulsions are discussed.
    Additional Material: 11 Ill.
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    URL: http://dx.doi.org/10.1002/apmc.1992.051960106
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    On the polymerization of acrylonitrile in the presence of some unsaturated triazine derivatives (1992)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 196 (1992), S. 107-111 
    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 Acrylnitril in Gegonwart verschiedener ungesättigter optischer Aufheller (FB) (Derivate des 1,3,5-Triazins) wurde untersucht. Kolorimetrische Messungen ergaben, daß mehr als 80% des optischen Aufhellers in die Polymerkette eingebaut werden. Zur Erzielung eines intensiven optischen Effektes genügt eine FB-Anfangskonzentration von 0,1 Gew.-%, bezogen auf Acrylnitril.
    Notes: The polymerization of acrylonitrile in the presence of some unsaturated, triazinebased fluorescent brighteners (FB) has been investigated. It was found colourimetrically that more than 80% of the FB is incorporated in the polymer. The initial concentration of 0.1 wt.-% is sufficient to obtain a good bleaching effect without significant decrease of the molecular weight.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1992.051960109
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  • 59
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    Tough thermoplastic polyesters by reactive extrusion with epoxy-containing copolymersPaper presented at the Sixth Annual Meeting of the Polymer Processing Society at Nice, April 17-20, 1991. (1992)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 196 (1992), S. 89-99 
    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: Les polyesters thermoplastiques (PBT et PET) sont des polymères fragiles avec une résistance au choc entaillée faible. Leur renforcement peut être obtenu par extrusion réactive avec dirrérents types de copolymères élastomères de l'éthylène, contenant des fonctons à réactivité potentielle avec extrémités de chaîne acide et hydroxyle des polyesters.Deux types de copolymères ont été étudiés: Ethylène(acrylate d'éthyle/méthacrylate de glycidyle (E/EA/GMA), et éthylène/acrylate d'éthyle/anhydride maléique (E/EA/MAH). Les alliages ont été obtenu par malaxage de 10 à 25% de coppolymères avec du PBT.Le PBT présente une transition fragile, ductile lorsqu'on passe de 10 à 20% de particules dispersées de copolymère au GMA. Les gains les plus importants en résistance au choc sont obtenus en réticulant partiellement la phase dispersée, par association de copolymères en GMA et de copolymères avec MAH et catalyseur de réaction.
    Notes: Poly(butylene terephthalate) (PBT) and poly(ethylene terephthalate) (PET) are brittle polymers with poor notched impact strength. Their toughening can be achieved by melt blending with different types of rubbery ethylene copolymers containing functions having potential reactivity with the hydroxy and carboxy end groups in polyesters.Two types of ethylene copolymers were investigated: ethylene/ethyle acrylate/glycidyl methacrylate (E/EA/GMA) and ethylene/ethyl acrylate/maleic anhydride (E/EA/MAH) copolymers. The blends were obtained by reactive extrusion of PBT with 10 to 25% of copolymers.PBT blends undergo a brittle to ductile transition by toughening with GMA copolymer between 10 and 20% of rubbery phase. The most effective toughening could be achieved by a partial crosslinking of the rubbery particles obtained by associating GMA and MAH copolymers and a reaction catalyst.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1992.051960107
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    Relation between polymer surface tension and orientation of thermotropic liquid crystals (1992)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 196 (1992), S. 101-106 
    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: Die Orientierung (Neigungswinkel ϕ) von thermotropen Flüssigkristallen (LC) an der Grenzfläche zu polymerbeschichteten Substraten wird nicht nur durch den numerischen Wert der Oberflächenspannung \documentclass{article}\pagestyle{empty}\begin{document}${\rm \gamma }_{\rm S} {\rm }\left( {{\rm \gamma }_{\rm S} {\rm = \gamma }_{\rm S}^{\rm d} {\rm + \gamma }_{\rm S}^{\rm p} } \right)$\end{document} bestimmt. Das Verhältnis zwischenden dispersiven und polaren Anteilen an \documentclass{article}\pagestyle{empty}\begin{document}${\rm \gamma }_{\rm S} {\rm }\left( {{\rm \gamma }_{\rm S}^{\rm d} {\rm : \gamma }_{\rm S}^{\rm p} } \right)$\end{document} beeinflußt ebenfalls die Orientierung der LC-Moleküle an der Substratoberfläche. Als Polymere wurden ein Polyimid und ein Midgruppenhaltiges Styrol/Maleinsäureanhydrid-Copolymeres verwendet.
    Notes: The orientation (tilt angle ϕ) of thermotropic liquid crystals (LC) on the interface to a polymer-coated surface is not only determined by the numerical value \documentclass{article}\pagestyle{empty}\begin{document}${\rm \gamma }_{\rm S} {\rm }\left( {{\rm \gamma }_{\rm S} {\rm = \gamma }_{\rm S}^{\rm d} {\rm + \gamma }_{\rm S}^{\rm p} } \right)$\end{document} of the substrate surface tension. However, the ratio between the dispersive and the polar part of \documentclass{article}\pagestyle{empty}\begin{document}${\rm \gamma }_{\rm S} {\rm }\left( {{\rm\gamma }_{\rm S}^{\rm d} {\rm : \gamma }_{\rm S}^{\rm p} } \right)$\end{document} also influences the LC orientation on the substrate surface. A polyimide and an amide-modified styrene/maleic anhydride copolymer were used as polymers.
    Additional Material: 1 Tab.
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    URL: http://dx.doi.org/10.1002/apmc.1992.051960108
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    Preparation of prepolymers from diglycidylether of bisphenol A containing imide groups (1992)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 195 (1992), S. 129-137 
    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: Epoxidharze aus Bisphenol A wurden mit neuen Diphenolen, die Imidgruppen enthalten, modifiziert, um die thermischen Eigenschaften zu verbessern. Die verwendeten Diimiddiphenole wurden aus Dianhydriden und Aminophenolen durch Kondensation hergestellt. Die Diimiddiphenole und die modifizierten Harze wurden durch IR- und NMR-spektroskopische Messungen charakterisiert. Das thermische Verhalten wurde anhand von DSC- und TGA-Messungen untersucht.
    Notes: Epoxy resins derived from Bisphenol A have been modified with new diphenols containing imide moieties in order to improve their thermal properties. The diphenols have been synthesized from dianhydrides and aminophenols by condensation reactions. Diphenols as well as modified resins have been characterized by IR and NMR spectroscopy. The thermal characteristics were evaluated by DSC and TGA.
    Additional Material: 3 Ill.
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    URL: http://dx.doi.org/10.1002/apmc.1992.051950110
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  • 62
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    Die kristallisation eines geschmolzenen molekülkomplexes aus hochmolekularem polyoxyethylen und harnstoff (1992)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 195 (1992), S. 165-170 
    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 structural transformation of a molecular complex (MC) of polyoxyethylene and urea on cooling from the molten state has been investigated by DSC and X-ray analysis. A high-temperature polymorphic from of the MC was found to be formed, which transforms into the known crystal form of the MC with a hexagonal crystal modification on cooling.
    Notes: Die Strukturveränderungen eines Molekülkomplexes (MK) aus Polyoxyethylen und Harnstoff beim Abkühlen aus dem geschmolzenen Zustand werden kalorimetrisch und röntgenographisch untersucht. Es wird festgestellt, daß eine polymorphe Hochtemperaturform des MK entsteht, die beim Abkühlen in die bekannte Kristallform des MK mit hexagonaler Kristallmodifikation übergeht.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1992.051950113
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    Effect of ring size on the oxidizability of lactams (1992)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 196 (1992), S. 143-154 
    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 Anfangsstadium der Oxidation von Lactamen wurden im Temperaturbereich 70-120°C Cuntersucht. Es wurde festgestellt, daß Pyrrolidon und Piperidon bedeutend schneller oxidiert werden als die sieben-, acht- und dreizehngliedrigen Lactame sowie lineare N-Alkylamide. Die hohe Oxidierbarkeit der fünf- und sechsgliedrigen Lactame kann der leichteren homolytischen Spaltung der N- vicinalen C—H Bindung und der unterschiedlichen Reaktivität der Lactamradikale im Wachstuschritt der Kettenoxidation zugeschrieben werden.
    Notes: The initial stage of oxidation of lactams was studied in the temperature range 70-120°C. It was found that pyrrolidone and piperidone are oxidized essentially more easily than the seven-, eight-, nine- and thirteen-membered lactams as well as linear N-alkylamides. The high oxidizability of the five- and six-membered lactams may be attributed to the easier homolytic splitting of the N-vicinal C—H bond and to the different reactivity of lactam radicals in the propagation step of the chain oxidation.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1992.051960112
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    Reaktionsverhalten des Natriumallylsulfonats in der Lösungscopolymerisation des Acrylnitrils in Dimethylformamid (1992)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 196 (1992), S. 127-141 
    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 relative chain transfer constant for sodium allylsulfonate (NaAS) in the copolymer system acrylonitrile (AN)/methylacrylate (MA) in dimethylformamide (DMF) was determined to be Cx = 0,04 ± 0.01, independent of the initiator used (azoisobutyronitrile, ammoniumperoxodisulfate).The chain transfer reaction explains the influence of NaAS on the polymerization degree, but not the concentration dependence of the copolymerization reactivity ratio r1 · r1 depends on the transfer reaction only in a range of 1 - 5%.The extended Debye-Hückel theory for dilute electrolytes has been successfully tested for a quantitative dependence of r1 from NaAS concentration. The resultant r10-value for infinite dilution of NaAS obviously depends on the acrylonitrile concentration, but only to a small extent (e.g. r10 = 0.32 for [AN] =- 4.26 mol/l). This theory provides comfortable access to resolve the nonideal AN/NaAS copolymerization. This approach may be generally applicable to copolymerizations of monomers with dissociated groups.
    Notes: Im Copolymerisationssystem Acrylnitril (AN)/Methylacrylat(MA) mit Natriumallylsulfonat (NaAS) in Dimethylformamid wurde die relative Übertragunskonstante zum NaAS Cx = 0,04 ± 0,01 unabhängig vom verwendeten Initiator (Azoisobuttyronitril, Ammoniumperoxodisulfat) ermittelt. Die Übertragunsreaktion beschreibt den Einfluß des NaAS auf den Polymerisationsgrad, sie beeinflußt jedoch den Copolymerisationsparameter r1 nur in der Größenordung von 1 bis 5% und kann damit die Konzentrationsabhängigkeit von r1 nicht erklären.Mit Hilfe der erweiterten Debye-Hückel-Theorie für verdünnte Elektrolyte wird die Abhängigkiet des r1-Wertes von der NaAS- Konzentration beschrieben. Der sich daraus für unendliche Verünnung des NaAS ergebende r10-Wert ist offensichtlich noch gerinfügig von der Acrylnitrilkonzentration abhägig. Er liegt beispielsweise für [AN] = 4, 26 mol/1 bei r10 = 0, 32. Damit wurde zum ersten Mal das nichtideale Copolymerisationsverhalten im untersuchten System erkärl. Das Vorgehen sollte verallemeinerungsfähig sein und generell auf das Copolymerisationsverhalten von Monomeren mitdissoziierten Gruppen angewendet werden können.
    Additional Material: 4 Ill.
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    URL: http://dx.doi.org/10.1002/apmc.1992.051960111
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    Photosynthetic membranes, 21. Immobilization of catalase by photochemically grafted ultrafiltration membranes (1992)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 196 (1992), S. 169-177 
    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: Katalase wurde durch photoinduzeirte Propfpolymerisation auf mikroporöse polymere Trägermembranen immobilisiert. Die katalytische Aktivität für Zersetzung von Wasserstoffperoxid unter Ultrafitrationsbedingungen wurde mittels eines Rezirkulationsapparates untersucht. Die Membranen zeigten ein sehr gutes katalytisches Verhalten; die Enzymreaktion fand ausschließlich in der Membranstruktur statt. Anfangsreaktionsgeschwindigkeiten, gemessen in einem Temperaturbereich von 5-35°C als Funkation der Substratkonzentration und der Menge des immobilisierten Enzyms pro Einheit Membranoberfäche zeigten, daß sich der Reaktionsmechanismus der Katalase durch die Immobilisierung nicht verädert.
    Notes: Catalase has been immobilized in membranes prepared by photoinduced grafting onto microporous polymeric supports and its catalytic activity on hydrogen peroxide decomposition has been studied under ultrafiltration conditions by means of a recirculation apparatus. The membranes showed a very good catalytic performance and the enzyme reaction took place exclusively within the membrane structure. Initial reaction rates measured in the temperature range 5 - 35°C as a function of both substrate concentration and enzyme amount immobilized per unit membrane surface indicate that the mechanism of action of catalase is not altered after immobilization.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1992.051960114
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    Untersuchungen zum Netzwerkbildungsprozeß bei der Reaktion von Bisphenol A-Diglycidylether mit 4,4′-Diaminodiphenylmethan (1992)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 196 (1992), S. 195-206 
    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 network formation process of bisphenol A-diglycidylether and 4,4′-diaminodiphenylmethane was investigated by measuring the torque, the conductivity and the soluble part of the crosslinking system. The activation energy for the curing process was estimated from gel time. The volume shrinkage during network formation was measured. The influence of N,N-dimethylbenzylamine as accelerator was discussed.
    Notes: Der Aufbau von Netwerken aus Bisphenol A-Diglycidylether und 4,4′-Diaminodiphenylmethan wurde durch Messung des Drehmomentes, der Leitfähigkeit und durch Bestimmung der löslichen Anteile des vernetzenden System untersucht. Aus den Gelzeiten wurden die Aktivierungsenergie für den Vernetzungsprozeß bestimmt. Außerdem wurde die während der Vernetzung aufretende Volumenschwindung gemessen. Der Einfluß von N, N-Dimethylbenzylamin als Beschleuniger auf den Vernetzungsprozeß wird diskutiert.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1992.051960116
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    Oberflächenstrukturierung polymerer Fasern durch UV-Laserbestrahlung. 13. Oberflächenstrukturierung von HochleistungsfasernTeil 12 cf. Lit.5. (1992)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 196 (1992), S. 179-194 
    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 UV-laser induced surface modification of various types of high-performance fibers is investigated. Due to the high UV-absorption coefficients, the well-known effect of UV-laser induced etching (ablation) is observed with all fiber types. Furthermore, the relaxation of orientated macromolecules leads to a characteristic structuring of the fiber surface. For a possible controlled use of this physical surface modification, exact conditions for the treatment in view of textile applications are determined. Useful constants like threshold of ablation, etching rate and structuring constants are measured for all fiber types.
    Notes: Die Oberflächenbehandlung von unterschiedlichen Hochleistungsfasertypen mit gepulstem UV- Laserlicht wird untersucht. Bedingt durch die hohen UV-Absorptionskoeffizienten dieser Materialien wird der bekannte Effekt des UV-laserinduzierten Abtrags (Ablation) bei allen Fasern beobachtet. Zusätzlich werden durch die Relaxation der orientierten Makromoleküle charakteristische Strukturierungen auf der Faseroberfläche ausgebildet. Für einen möglichen kontrollierten und gezielten Einsatz dieser physikalischen Oberflächenmodifizierung in textilen Anwendungen werden die gnaunen Bedingungen der Laserbestrahlung ermittelt und beschieben. Darüber hinaus werden geeignete Konstanten der Laserbearbeitung wie Ablationsschwellenenergie, Ätzraten und Strukturierungskonstanten für verschiedene Fasertypen bestimmt.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1992.051960115
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    Kinetics of the free radical polymerization of dimethyl diallyl ammonium chloride, 5Part 4 cf. Acta Polym. 35 (1984) 350.. Kinetic model with persulfate as initiator (1992)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 198 (1992), S. 165-178 
    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 Dimethyl-diallyl-ammoniumchlorid in konzentrierter wäßriger Lösung mit Persulfat als Initiator kann bis zu hohen Umsätzen mit einem Modell beschrieben werden, in dem folgende Teilreaktionen berücksichtigt werden: a)Primärradikalbildung durch aktivierten Initiatorzerfall sowie Redoxreaktion von S2O2-8 und Cl-b)Kettenwachstum über Monomerkationassoziate undc)Kettenabbruch durch Kombination von cyclisierten Polymerradikalen untereinan der und mit Chloratomen.Für die Polymerisationsgeschwindigkeit wird ein Zeitgesetz hergeleitet, für dessen Konstanten und Parameter numerische Werte ermittelt wurden.
    Notes: The polymerization of dimethyl diallyl ammonium chloride in concentrated aqueous solution with persulfate as an initiator can be described up to high conversion by a kinetic model including a)formation of primary radicals by activated initiator decomposition as well as by redox reaction of S2O82- and Cl-,b)chain propagation via monomer cation associates andc)termination by combination of cyclized polymer radicals between each other or with chlorine atoms.A kinetic expression for the rate of polymerization is presented; rate constants and model parameters have been determined.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1992.051980114
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    Announcements (1992)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 198 (1992), S. 199-199 
    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.1992.051980117
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  • 70
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    Synthesis and transition metal complex binding of amines and amides covalently bound to crosslinked polystyrene (1992)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 198 (1992), S. 179-190 
    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: Polymere mit über eine C—C-Verknüpfung an hochvernetztem Polystyrol kovalent gebundenen, makrocyclischen Amiden wurden durch die Reaktion polymergebundener Malonsäureester-Gruppen mit offenkettigen Diaminen dargestellt. Die Reaktion von vernetztem, chlormethyliertem Polystyrol mit makrocyclischen und offenkettigen Aminen führt zu Polymeren mit kovalenter Bindung über eine C—N-Verknüpfung. Die erhaltenen funktionalisierten Polymeren wurden hinsichtlich der Adsorption von Cu(II)-, Ni(II)- und Co(II)-Ionen aus wäßriger Lösung untersucht.
    Notes: Polymers containing moieties of amides covalently bound to highly crosslinked polystyrene by C—C connections were prepared via a polymer-bound malonic ester group in the reaction with open-chain diamines. The reaction of crosslinked, chloromethylated polystyrene with macrocyclic and open-chain amines results in covalent binding by C—N-connection. The synthesized functionalized polymers were investigated for uptake of Cu(II), Ni(II) and Co(II) ions from aqueous solutions.
    Additional Material: 1 Ill.
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    URL: http://dx.doi.org/10.1002/apmc.1992.051980115
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    Synthesis of a poly(terephthaloylphosphine) (1992)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 199 (1992), S. 1-6 
    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(phenylphosphindiylterephthaloyl), ein neues phosphorhaltiges Polymeres, wurde durch Lösungspolykondensation von Dilithium(phenyl)phosphin mit Terephthaloylchlorid bei niedriger Temperatur hergestellt. Es ist in polaren aprotischen Lösungsmitteln löslich; die inhärente Viskosität in DMF bei 30°C beträgt 19 ml/g. Das Polymere wurde mittels Elementaranalyse sowie IR- und 1H-NMR-Spektroskopie charakterisiert. TGA-Messungen ergeben, daß das Polymere in Luft bis 250°C stabil ist; es ist selbstverlöschend.
    Notes: Poly(phenylphosphinediylterephthaloyl), a novel phosphorus-containing polymer, was synthesized by low-temperature solution polycondensation of dilithio(phenyl)-phosphine with terephthaloyl chloride. The resulting polymer is soluble in polar aprotic solvents, having inherent viscosity of 19 ml/g in DMF at 30°C. The polymer was characterized by elemental analysis, IR and 1H-NMR spectroscopy. TGA data show that the polymer is stable up to 250°C in air. The polymer was found to be self-extinguishing.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1992.051990101
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    Extension of the measuring range in size exclusion chromatography to higher molar mass by use of a light scattering detectorDedicated to Professor Dr. Dr. h. c. mult. Otto Kratky on the occasion of his 90th birthday (1992)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 199 (1992), S. 7-14 
    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 eine neue Methode für die Erweiterung des Meßbereiches der Ausschlußchromatographie, gekoppelt mit Lichtstreuung (SEC/LALLS), zu höherer molarer Masse, vorgestellt. Diese Methode nützt den Effekt, daß das Lichtstreusignal oft schon bei wesentlich kleineren Werten des Elutionsvolumens, also hoheren Werten der molaren Masse erfaßbar ist als das Konzentrationssignal und berücksichtigt dabei die Peakverbreiterung in der SEC. Das betreffende Rechenverfahren wird für den Fall einer logarithmischen Normalverteiung und einer wahrscheinlichsten Verteilung getestet. Im Falle von Polypropylen mit logarithmischer Normalverteilung (M̄W = 420 000 und M̄n = 99 000) kann der durch SEC/LALLS erfaßte Bereich der molaren Masse um einen Faktor von ca. 10 erweitert werden; bei einer wahrscheinlichsten Verteilung (M̄n = 100 000) liegt die erreichbare Erweiterung des Meßbereiches der molaren Masse beieinem Faktor von ca. 2.
    Notes: A new method for the extension of the measuring range of size exclusion chromatography coupled with light scattering (SEC/LALLS) to higher molar mass is presented. This method uses the fact that the light scattering signal can often be detected already at considerable smaller values of the elution volume (i. e. higher values of molar mass) than the concentration signal; furthermore, it takes into account the peak broadening effect in SEC. This procedure is tested for the case of a logarithmic normal distribution and a most probable distribution of molar mass. In the case of polypropylene with a logarithmic normal distribution (M̄w = 420 000, M̄n = 99 000), the range of molar mass covered by SEC/LALLS can be extended by a factor of about 10; with a most probable distribution (M̄n = 100 000), the attainable extension in molar mass assumes a factor of about 2.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1992.051990102
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    Sorptionsverhalten von nativer und thermoplastischer stärke (1992)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 199 (1992), S. 45-63 
    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: Because of the interest in their possible application as biologically degradable polymers, the isotherms of sorption of water vapour by native and thermoplastic starch were measured. The thermomechanical treatment of starch and the insertion of glycerol as softener lead to the disappearance of the hysteresis and to the transition from a Type II to Type III isotherm. A theory, describing the sorption behaviour of swellable sorbents, is introduced and its statements are discussed by means of experimental results. The theory allows to draw conclusions on the molecular behaviour during sorption.
    Notes: Es wurden Wasserdampf-Sorptionsisothermen von nativer und thermoplastischer Stärke gemessen. Die thermisch-mechanische Behandlung der Stärke und das Einfähren von Glyzerin als Weichmacher fährt zum Verschwinden der Hysterese und zum Übergang von der Typ II in eine Typ III Isotherme. Eine Theorie, welche das Sorptionsverhalten von quellbaren Sorbentien gut beschreibt, wird kurz eingeführt und anhand der experimentellen Daten ihre Aussagen diskutiert. Die vorgestellte Theorie erlaubt wegen der physikalischen Bedeutung der Parameter Rückschlüsse auf die molekularen Vorgänge während der Sorption. Die Motivation zur Untersuchung des Sorptionsverhaltens von thermoplastischer Stärke ist deren möglicher Einsatz als biologisch abbaubarer Kunststoff.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1992.051990105
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    Etudes microlithographiques de résines négatives renfermant des unités tétrathiafulvalènes sensibles aux UV (1992)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 199 (1992), S. 15-31 
    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: In order to solve the problem of polymer swelling which limits the resolution of negative resists, we have developed new resists where the swelling does not appear. For our study, we developed resists including polymers containing the tetrathiafulvalenylcarbonyloxymethyl radical and dibromotetrachloroethane. In order to study the influence of the nature of the radical bearing the tetrathiafulvalene unit in the polymers on the microlithographic properties of these resists, we also studied polymers containing the tetrathiafulvalenylphenoxymethyl radical. The resists have been tested under UV irradiation. The dependence of resist sensitivity on molecular weight is reported.
    Notes: Pour résoudre le phéomène de gonflement qui limite la résolution des résines microlithographiques classiques, nous nous sommes intéressés à de nouvelles résines avec lesquelles ce phénomène n'apparait pas. Nous avons retenu pour notre étude les résines R qui renferment en mélange un polymère porteur de radicaux tétrathiafulvalénylcarbonyloxyméthyles et le dibromotétrachloroéthane. Afin de voir l'influence de la nature du radical porteur de l'unité tétrathiafulvalène dans le polymtrè sur les propriétés microlithographiques des résines R, nous nous sommes également intéressés aux polymères renfermant des radicaux tétrathiafulvalénylphénoxymethyles. Les résines R ont été testées sous irradiation UV. Leurs sensibilités dépendent en outre de la valeur de la masse molaire du polymèr.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1992.051990103
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    Photoinitiated surface grafting of synthetic fibers, IV. Applications of textile dyes onto surface-photografted synthetic fibers (1992)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 199 (1992), S. 33-44 
    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: Hochfeste Polyethylen- (HSPE), Polypropylen- (PP), Polyethylenterephthalat-(PET) und Polyvinylalkohol-(PVA) Textilgarne wurden unter Anwendung des entwickelten kontinuierlichen Einweichprozesses mit verschiedenen funktionellen Monomeren, wie beispielsweise Acrylsäure (AA), Acrylamid (AM), Glycidylacrylat (GA) und 4-Vinylpyridin (VP) oberflächenfotogepfropft. Die Einfärbbarkeit der oberflächenmodifizierten Garne mit verschiedenen Textilfarbstoffen wurde untersucht. Im allgemeinen wurde eine erhebliche Verbesserung der Einfärbbarkeit beobachtet. Die Farbstoffaufnahme der oberflächenfotogepfropften Fasern wird von vielen Faktoren beeinflußt, beispielsweise von der Art der Faser, der Menge und den Eigenschaften des auf die Oberfläche der Fasern gepfropften funktionellen Monomeren, der Art des Textilfarbstoffs usw. Die Faseroberflächen, auf die ein Monomeres mit basischen Gruppen wie Acrylamid und 4-Vinylpyridin gepfropft wurde, lassen sich mit einem sauren Farbstoff wirkungsvoll einfärben. Dagegen läßt sich eine Faseroberfläche, auf die ein saures funktionelles Monomeres gepfropft wurde, leicht mit basischen Farbstoffen in tiefen Farbtönen einfärben. Die Farbstoffaufnahme steigt stetig mit zunehmender Pfropfung, in ESCA-Spectren als relative Intensitaten relevanter Linien gemessen. Die nicht gepfropften HSPE-, PP-, und PET-Fasern können mit bestimmten Farbstoffen in gewissem Maße eingefärbt werden. Bei der vorliegenden Arbeit erhöhte sich die Farbstoffaufnahme bei HSPE-Fasern, die mit GA gepfropft und mit dem Metallkomplexfarbstoff IO eingefärbt wurden, um das 3,4fache, bei PP-Fasern, die mit AA gepfropft und mit dem basischen Farbstoff MB eingefärbt wurden, um das 7,9fache, bei PET mit AM und dem Direktfarbstoff SL um das 6,1fache, bei PVA mit VP und dem sauren Farbstoff TE um das 15,3fache.
    Notes: High-strength polyethylene (HSPE), polypropylene (PP), poly(ethylene terephthalate) (PET), and poly(vinyl alcohol) (PVA) textile yarns have been surface-photografted with various functional monomers, such as acrylic acid (AA), acrylamide (AM), glycidyl acrylate (GA) and 4-vinyl pyridine (VP), by means of the continuous presoaking process developed. The dyeing of these surface-modified yarns with various textile dyes has been investigated. In general, considerable improvements of dyeability have been observed. The dye adsorption of the surface-photografted fibers is influenced by many factors, such as type of fiber, amount and properties of the functional monomer grafted on the surface of the fibers, type of textile dye, etc. The fibers surface-grafted with a monomer containing basic groups, such as acrylamide and 4-vinyl pyridine, are efficiently dyed with an acid dye. Conversely, a fiber surface-grafted with acidic functional monomer is easily dyed to deep shades with basic dyes. The dye adsorption increases monotonically with increasing grafting measured in ESCA spectra as relative intensities of relevant lines. The ungrafted HSPE, PP and PET fibers can be dyed to some extent with certain dyes. In the present work, the dye adsorption increased by 3.4 times for HSPE fiber grafted with GA and dyed with the metal complex dye IO, by 7.9 times for PP fiber grafted with AA and dyed with the basic dye MB, by 6.1 times for PET with AM and with the direct dye SL, and by about 15.3 times for PVA with VP and with the acid dye TE.
    Additional Material: 1 Ill.
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    URL: http://dx.doi.org/10.1002/apmc.1992.051990104
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    Study on the thermal behaviour of copolymers of acrylonitrile with halogenated carboxylic acids (1992)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 199 (1992), S. 65-74 
    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: Die thermische Stabilität von Acrylnitril-Copolymeren wurde mittels DSC untersucht, um den Einfluß von halogenierten Comonomeren mit Carboxygruppen auf die Stabilisierung von PAN zu präfen. Es wird gezeigt, daß die Aktivierungsenergie fär die Cyclisierung des AN/Bromacrylsäure(BrAA)-Copolymeren (86,2 kJ/mol) deutlich niedriger als die der Copolymeren mit Chloracrylsäure (ClAA, 158 kJ/mol), Acrylsäure (AA, 128 kJ/mol) und Itaconsäure (IA, 102 kJ/mol) ist. Das erlaubt eine Stabilisierung bei häherer Temperatur und eine Verkürzung der Stabilisierungszeit. ClAA ist BrAA bezäglich der Stabilisierungseffektivität nicht überlegen. Der Mechanismus der Cyclisierung von AN-Copolymeren mit halogenierten, carboxygruppenhaltigen Comonomeren wird diskutiert.
    Notes: The thermal stability of AN copolymers was studied by DSC technique in order to get information on the influence of comonomers containing halogenated carboxylic acid on the stabilization of PAN. It is shown that the activation energy of cyclization is reduced in the case of the copolymer with bromoacrylic acid (BrAA, 86.2 kJ/mol) compared with chloroacrylic acid (ClAA, 158 kJ/mol), acrylic acid (AA, 128 kJ/mol) and itaconic acid (IA, 102 kJ/mol). Copolymer AN/BrAA permits the stabilization at higher temperature than AN/IA and AN/AA, helping to shorten the stabilization time. It is proved that comonomer ClAA is not superior to BrAA in the effectiveness of thermal stabilization. The mechanism of the cyclization reaction of AN copolymer containing halogenated carboxylic acid is discussed.
    Additional Material: 3 Ill.
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    URL: http://dx.doi.org/10.1002/apmc.1992.051990106
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    New unsymmetrical cycloaliphatic epoxypolyesterimides (1992)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 199 (1992), S. 75-85 
    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 neue unsymmetrische cycloaliphatische Bisepoxyderivative hergestellt. Die unterschiedliche Reaktionsfahigkeit der zwei Oxiranringe (cycloaliphatisch und glycidylisch) gegenüber Carbonsäure wurde untersucht, wobei eine normale und anomale Ringöffnung der Glycidylgruppen beobachtet wurde. Eine Homopolymerisation des Oxirans wurde ebenfalls beobachtet. Mit Hilfe der 13C-NMR-Spektroskopie wurde die Struktur der Polymeren ermittelt. Die neuen Epoxidharze zeigen gute thermische Eigenschaften.
    Notes: New bisepoxy unsymmetrical cycloaliphatic derivatives have been synthesized. The different reactivity of both oxirane rings (cycloaliphatic and glycidylic) has been tested against carboxylic acids giving rise to normal and abnormal opening to the glycidyl group. Homopolymerization reaction was also observed. Polymer structures were identified by 13C-NMR spectroscopy. Thermal analysis carried out allowed to confirm their good thermal properties.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1992.051990107
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    Struktur und eigenschaften von simultanvernetzten bismaleimidmodifizierten novolak-epoxidharzen (1992)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 194 (1992), S. 119-131 
    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: N,N′-4,4′-Diphenylmethane-bismaleimide (BMI) was oligomerized in semisolid phenolnovolak epoxide-resin (EP) up to P̄n = 10. The morphology of the novolakcured EP-BMI solid resins is a two-phase structure. It consists in a homogeneous EP-BMI phase of an interpenetrating polymer network (IPN) and a BMI phase. The dynamic-mechanical properties depend on the overall weight fraction w2 of BMI and on the degree of oligomerization (P̄)n of BMI. The relative shear modulus of the EP-EMI resin in the rubber state shows that both phases can be coherent. The glass transition temperature (Tg) can be correlated with the degree of oligomerization of the BMI, for instance Δ P̄n ≡ 10 corresponds to Δ Tg ≡ 35 K and Δ wx2 ≡ 0,25 (weight fraction of BMI in the homogeneous EP-BMI phase). Surprisingly, the breaking strength remains constant.
    Notes: N,N′-4,4′-Diphenylmethan-bismaleimid (BMI) wurde in halbfesten Phenolnovolak-Epoxidharzen (EP) bis P̄, = 10 oligomerisiert. Die novolakgehärteten EP-BMI-Festharze bilden eine Zweiphasenstruktur, bestehend aus einer EP-BMI-Mischphase der beiden sich durchdringenden Netzwerke (interpenetrating polymer network, IPN) und einer BMI-Phase. Die dynamisch-mechanischen Eigenschaften hängen vom Gesamt-BMI-Anteil w2 und vom Oligomerisierungsgrad P̄n des BMI ab. Der relative Schubmodul des EP-BMI-Harzes im kautschukelastischen Zustand zeigt, daß beide Phasen kohärent sein können. Die Glastemperatur Tg korreliert mit dem Oligomerisierungsgrad, z. B. entspricht ΔPn ≡ 10 einem ΔTg ≡ 35 K und einem BMI-Anteil Δ wx2 ≡ 0,25 in der Mischphase. Die Bruchzahigkeit bleibt unerwartet konstant.
    Additional Material: 8 Ill.
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    URL: http://dx.doi.org/10.1002/apmc.1992.051940110
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    Studies on new non-shrinking, thermally stable, aralditeRegistered trade mark of CIBA-GEIGY AG.-type photopolymers with pendent arylacryloyl groups III. Photopolymers with pendent cinnamic acid ester and furan acrylic ester groups and their reactions with low molar mass modifiersPart II: Angew. Makromol. Chem. 191 (1991) 191. (1992)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 194 (1992), S. 103-117 
    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: Handelsübliche Araldit™-Polymere wurden mit Zimtsäure- bzw. Furanacrylsäurechlorid modifiziert und über [2 + 2]-Cycloaddition photochemisch vernetzt. Die Glasübergangstemperaturen der entstandenen Polymeren betragen bis zu 130°C bei Dielektrizitätskonstanten von ∊r = 3.0. Daher können diese Polymeren in Mehrlagenmikroverdrahtungen verwendet werden. Zahlreiche wohldefinierte, multifunktionelle Modifikatoren wurden synthetisiert und deren Einfluß auf die Polymerisation und die Eigenschaften der Araldit™-Polymeren eingehend untersucht.
    Notes: Commercially available Araldite™-type polymers have been modified with cinnamic and furan acrylic acid chlorides. The polymers were photochemically crosslinked via a [2 + 2] cycloaddition. The resulting polymers show glass transition temperatures up to 130°C and dielectrical constants of ∊r = 3.0. Therefore, these polymers can be applied as permanent resists in multi-layered wiring structures. Numerous well-defined multifunctional modifiers have been synthesized. The effect of those modifiers on the polymerization and properties of the araldite-type polymers has been studied in some detail.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1992.051940109
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    Photovernetzung von siliconen, 8. Netzwerkcharakterisierung photovernetzter siliconacrylate7. Mitteilung vgl.1. (1992)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 200 (1992), S. 61-76 
    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 photoinduced free radical crosslinking of silicone containing pendent acrylate or methacrylate groups was investigated by swelling measurements. A modified swelling test was applied to observe the network formation as a function of several parameters. The results show that the network density of the crosslinked polymers is a function of the light intensity, the exposure time, the acrylate content, the molecular weight of the uncrosslinked silicone acrylate and also of the length of the spacer group between the acrylate unit and the silicone backbone. Oxygen has only an influence on the polymerization kinetics, but it does not influence the network density.From the δB, -values of crosslinked silicone acrylates and silicone containing vinyl groups it is possible to analyze the structure of the network as a function of the olefinic group. The χ-parameters of both silicone types are of the same magnitude in the same concentration range.Kinetics investigations demonstrate that the order of the network formation is nearly unity. This result agrees with the polymerization kinetics.By means of swelling measurements it is also possible to study the influence of hydrogen siloxane additives as hydrogen transfer reagents.
    Notes: Die photoinduzierte radikalische Vernetzung von Siliconacrylaten bzw. -methacrylaten wurde mit Hilfe von Quellungsmessungen untersucht, wobei ein modifizierter Quellungstest erlaubt, die Netzwerkbildung als Funktion verschiedener Parameter zu betrachten. Die Ergebnisse zeigen, daß die Netzwerkdichte eine Funktion der Lichtintensität, der Bestrahlungszeit, des Acrylatgehalts, der Molmasse des unvernetzten Silicons und auch der Länge der Spacergruppe zwischen Acrylateinheit und dem Siliconrückgrat ist. Sauerstoff besitzt dagegen nur einen Einfluß auf die Polymerisationskinetik, nicht aber auf die Netzwerkdichte.Aus dem Vergleich der δB, -Werte der vernetzten Siliconacrylate und der vernetzten Vinylsilicone kann geschlossen werden, daß die Netzwerkstruktur auch vom Typ der olefinischen Gruppen abhängt. Die χ-Parameter besitzen jedoch im gleichen Konzentrationsbereich die gleiche Größe.Kinetische Untersuchungen zeigen, daß die Netzwerkbildung nach einem Zeitgesetz erster Ordnung verläuft. Dieses Ergebnis steht im Einklang mit der Polymerisationskinetik.Mit Hilfe der Quellexperimente ist es auch moglich, den Einfluß von H-Siloxanzusätzen als Wasserstoffüberträger zu untersuchen.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1992.052000106
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  • 81
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    Synthese und charakterisierung von butadien-divinylbenzol-copolymeren (1992)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 194 (1992), S. 133-148 
    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 copolymerization of butadiene with a technical divinylbenzene fraction was investigated to study the modification of cis-1,4 polybutadiene. Beside the Ziegler-Natta-catalyst nickeloctanoate/bortrifluoride/aluminiumtriethyl, another catalytic system consisting of nickeloctanoate/titaniumtetrachloride/aluminiumtriethyl was used, which allows to polymerize more divinylbenzene because of its higher activity toward vinylaromates. With the help of spectroscopical, pyrolysis-gaschromatographical and thermoanalytical methods one can obtain relations between glass-, crystallization- and melting temperature and the microstructure of the polymer. It can be shown that not only the divinylbenzene but also the trans-1,4- and the 1,2-vinyl units are statistically distributed in the polymer. By this, beside the pyrolysis-gaschromatography, particularly the differential scanning calorimetry is a useful tool to characterize the structure of partially crosslinked polymers obtained from polymerization of technical fractions.
    Notes: Im Rahmen von Arbeiten zur Modifizierung des cis-1,6Polybutadiens wurde die Copolymerisation von Butadien und einer Divinylbenzolfraktion, insbesondere der Bereich mit kleinen Divinylbenzolgehalten, untersucht. Neben dem Ziegler-Natta-Katalysator Nickeloctanoat/Bortrifluoridetherat/Aluminiumtriethyl kam auch ein Nickeloctanoat/Titantetrachlorid/Aluminiumtriethyl-System zur Anwendung, welches es durch seine höhere Aktivität gegenüber Vinylaromaten ermöglicht, großere Mengen der Divinylbenzolfraktion zu polymerisieren. Durch die Anwendung von spektroskopischen, pyrolysegaschromatographischen und thermoanalytischen Charakterisierungsmethoden können Beziehungen zwischen den erhaltenen Glas-, Kristallisations- und Schmelztemperaturen und der Mikrostruktur des Polymeren hergestellt werden. Es zeigt sich, daß sowohl das Divinylbenzol als auch die trans-1,4 bzw. die 1,2-Vinyl-Einheiten statistisch in das Polymere eingebaut werden. Damit eignet sich neben der Pyrolysegaschromatographie besonders die Differential Scanning Calorimetry als eine einfache Methode zur Charakterisierung der Struktur von aus technischen Fraktionen erhaltenen und teilweise vernetzten Polymerproben.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1992.051940111
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  • 82
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    Effects of composition and plastifier on the light scattering of polymer glasses and properties of polymeric optical fibers made from styrene-methyl methacrylate copolymers (1992)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 194 (1992), S. 149-158 
    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: Optisch hochreine Gläser wurden aus Polystyrol (PS), Polymethylmethacrylat (PMMA) und statistischen Styrol-Methylmethacrylat-Copolymeren (S-MMA) hergestellt. Die an diesen Gläsern gemessene Lichtstreuung hängt von der chemischen Zusammensetzung des Polymeren und dem Brechungsindex des zugesetzten Weichmachers ab. Ein isorefraktiver Weichmacher verringert die Streuwerte der S-MMA-Copolymeren, hat aber keinen signifikanten Einfluß auf das Streuverhalten von PMMA. Ein Weichmacher mit einem vom Polymeren verschiedenen Brechungsindex verschlechtert die Streuwerte in allen untersuchten Fällen. Es wird gezeigt, daß ein isorefraktiver Weichmacher die Dämpfungseigenschaften von aus dem Copolymeren S-MMA 2/1 gezogenen polymeren Lichtleitern verbessert.
    Notes: High optical purity polystyrene (PS), poly(methyl methacrylate) (PMMA) and styrene-methyl methacrylate statistical copolymers (S-MMA) were prepared. Light scattering measured on polymeric glasses depends on the chemical composition of the polymer and on the refractive index of the plastifier added. An isorefractive plastifier reduces considerably the scattering values for the copolymers S-MMA, while having no significant effect on the scattering of PMMA. A plastifier with a refractive index different from that of the polymer raises distinctly the light scattering values in all cases. It has been shown that the isorefractive plastifier has a favourable effect on attenuation loss of polymeric optical fibers (POF) obtained from the copolymer S-MMA 2/1.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1992.051940112
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    Morphologiebildungs- und dispergiermechanismen bei der herstellung und verarbeitung von polymer-blends aus acrylnitril-butadien-styrol-(ABS)- bzw. Styrol-acrylnitril-(SAN)-copolymerisaten mit thermoplastischem polyurethan (TPU) (1992)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 194 (1992), S. 159-178 
    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: ABS/TPU- und SAN/TPU-blends were investigated on the basis of the analysis of viscoelastic behaviour of the components for characterization of the formation of morphology in melt mixing processes. Blends mixed in a laboratory kneeder and extruded from a high pressure capillary viscosimeter under definite conditions were characterized concerning their phase morphology by transmission electron microscopy. The types of morphology predicted by the help of rheological analysis could be confirmed by electron micrographs and quantitative analysis of morphology. It becomes evident, that the ratio of viscosity of the components has the primary influence on the formation of morphology in the blends. But also thermomechanically induced molecular destruction processes and thermodynamic interactions as well as connecting crystallisation conditions for the TPU-phase are not negligible with regard to resulting phase morphology.
    Notes: An ABS/TPU- bzw. SAN/TPU-Blends wurden Untersuchungen zur Morphologiebildung beim Schmelzemischen auf der Basis der Analyse des viskoelastischen Verhaltens der Komponenten angestellt. Unter definierten Bedingungen im Laborkneter gemischte und unter definierten Bedingungen mittels Hochdruckkapillarviskosimeter extrudierte Blendproben wurden hinsichtlich ihrer Phasenmorphologie elektronenmikroskopisch charakterisiert. Die mittels der rheologischen Analyse prognostizierten Morphologietypen und Morphologiebildungsmechanismen konnten anhand der elektronenmikroskopischen Aufnahmen und der quantitativen Morphologieanalyse bestätigt werden. Es zeigte sich, daß das Viskositätsverhältnis der Komponenten primären Einfluß auf die Morphologiebildung ausübt. Darüber hinaus sind auch thermomechanisch induzierte molekulare Abbauvorgänge und thermodynamische Wechselwirkungen sowie damit im Zusammenhang stehende Kristallisationsbedingungen für die TPU-Phase hinsichtlich der resultierenden Phasenmorphologie nicht zu vernachlässigen.
    Additional Material: 14 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1992.051940113
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  • 84
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    On the effect of water on the durability of PP and PC/acrylic adhesive joints (1992)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 194 (1992), S. 189-200 
    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 Stabilität von Verbindungen von Polypropylen (PP) und Polycarbonat (PC) mit einem Acryl-Kleber wurde mit einer thermodynamischen, auf der Messung von Oberflächenspannungen beruhenden Methode bestimmt.Die Charakterisierung der Oberflächen zeigte, daß eine Plasmabehandlung die Bildung einer sauerstoffreichen Oberflächenschicht bewirkt. Eine Lagerung in Wasser führt bei PP zu keiner Veränderung dieser Schicht, während bei PC niedermolekulare, oxidierte Verbindungen ausgewaschen werden.Sowohl unbehandelte als auch mit Plasma behandelte PP-Verbindungen wiesen bei Lagerung in Wasser eine annehmbare Stabilität auf. Zwar wurde eine geringe Abnahme der Scherfestigkeit gemessen, aber unbehandeltes und plasmabehandeltes PP zeigten weiterhin adhäsives bzw. kohäsives Bruchverhalten.Im Falle von PC blieben nur die aus unbehandeltem PC hergestellten Verbindungen ausreichend stabil, während die aus plasmabehandeltem PC hergestellten Verbindungen stark abgebaut wurden. Bei den letzteren wanderte der Versagensort an die Polymer/Kleber-Grenzfläche, was auf die Ausbildung einer sehr hydrophilen, niedermolekularen Schicht zurückgeführt wird.
    Notes: The stability of PP and PC/acrylic adhesive joints has been assessed using a thermodynamic method based on surface tension components.Surface characterization showed that plasma treatment induces the formation of an oxygen-rich layer on treated surfaces. In the case of PP this layer does not change its composition upon immersion in water, while for PC leaching of oxidized species with low molecular weight was observed.Both untreated and plasma treated PP joints showed reasonable stability against immersion in water. A small reduction of shear strength was observed, but the fracture remained adhesive for untreated PP and cohesive for plasma treated PP.In the case of PC, only joints made from untreated PC showed fair sensitivity against immersion in water, while those made from plasma treated specimens degraded dramatically. In the latter case the locus of failure moved to the adhesive/adherend interface, the presence of a very hydrophilic, low molecular weight layer being suggested as responsible for this behavior.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1992.051940115
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  • 85
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    Etude de l'oxydation de polystyrènes chlorométhylés renfermant de nouveaux radicaux tétrathiafulvalénylcarbonyloxyméthyles (1992)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 197 (1992), S. 89-106 
    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: The chloromethylated polystyrenes bearing tetrathiafulvalenylcarbonyloxymethyl groups can be oxidized. We have shown that ion radical salts are obtained from these polymers and carbon tetrabromide after irradiation with UV light. Charge transfer complexes were prepared by mixing these polymers and 2,3-dichloro-5,6-dicyanobenzoquinone. The possible presence of sulfoxides as a result of oxidation of some tetrathiafulvalene units could explain the difficulties we have observed to filter solutions of these polymers.
    Notes: Les polystyrènes chlorométhylés renfermant des radicaux tétrathiafulvalénylcarbonyloxyméthyles peuvent être oxydés. Ainsi la formation de sels d'ions radicaux obtenus à partir de ces polymères et de tétrabromure de carbone, irradiés sous UV, a été mise en évidence. Des complexes de transfert de charge ont été préparés en mettant en présence ces polymères et de la 2,3-dichloro-5,6-dicyanobenzoquinone. La présence de sulfoxydes non décelés et résultant de l'oxydation de certaines unités de tetrathiafulvalène contenus dans ces polymères pourrait expliquer les problèmes rencontrés lors de la filtration de leurs solutions.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1992.051970108
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    Metal complexation of poly[1-(2-hydroxyethyl)aziridine-co-2-methyl-2-oxazoline]Systematic name: Poly[(acetylimino)ethylene-co-(2-hydroxyethyleneimino)ethylene]. in aqueous solutionDedicated to Prof. Esen A. Bekturov on the occasion of his 60th birthday (1992)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 197 (1992), 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 Metallkomplexierung von wasserloslichem Poly[1-(2-hydroxyethyl)aziridin-co-2-methyl-2-oxazolin] mit Co(II), Zn(II), Ni(II), Cu(II), Cr(III), Fe(III), Cd(II), Pb(II) und Sr(II)-Ionen wurde in wäßriger Phase mit der Methode der Liquid-Phase Polymer-Based Retention (LPR) untersucht. Die Studie zeigt, daß alle Metallionen, außer Co(II) und Zn(II), bei pH 5 komplexiert wurden. Im Gegensatz zu Sr(II), das nur eine schwache Wechselwirkung in einem pH-Bereich von 3 bis 7 zeigte, wurden bei pH 7 94% Co(II) und 88% Zn(II) retentiert. Bei pH 3 zeigten nur Cu(II) und Cr(III) eine Wechselwirkung mit dem Polymeren, wobei die Retentionswerte 76% für Cu(II) und 52% für Cr(III) betrugen. Viskositätsmessungen des Copolymeren in Gegenwart von Metallionen wurden bei verschiedenen pH-Werten durchgeführt.
    Notes: The metal complexation of water-soluble poly[1-(2-hydroxyethyl)aziridine-co-2-methyl-2-oxazoline] with Co(II), Zn(II), Ni(II), Cu(II), Cr(III), Fe(III), Cd(II), Pb(II), and Sr(II) ions was investigated in aqueous phase using Liquid-Phase Polymer-Based Retention (LPR). The study shows that all metal ions are complexed at pH 5, except Co(II) and Zn(II). In contrast to Sr(II), which showed only a slight interaction over a pH range of 3 to 7, 94% of Co(II) and 88% of Zn(II) were retained at pH 7. At pH 3, only Cu(II) and Cr(III) ions interacted with the copolymer with retention values of 76% for Cu(II) and 52% for Cr(III). Viscosimetric measurements of the copolymer were performed in the presence of metal ions at different pH values.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1992.051970109
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    Preparation and uranyl ion adsorptivity of macroreticular chelating resins containing phosphono groups (1992)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 197 (1992), S. 117-129 
    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: Makroretikulare Copolymerperlen wurden durch Suspensionspolymerisation von Styrol, Bis(2-chlorethyl)vinylphosphonat (CEVP) und Divinylbenzol (DVB) in Gegenwart von Toluol als Verdünnungsmittel hergestellt. Die auf der Perlenoberfläche vorhandenen 2-Chlorethylphosphonat-Gruppen wurden durch Hydrolyse mit verdünnter Salpetersäure in Phosphon-Gruppen transformiert. Für die Einführung zusätzlicher Phosphon-Gruppen wurden die Copolymeren in Gegenwart von Aluminiumchlorid-Katalysator mit Phosphortrichlorid phosphoryliert, und die dabei entstandenen Dichlorphosphingruppen wurden mit verdünnter Salpetersäure verseift und oxidiert. Die Untersuchungen zur Chelatbildung der Copolymeren mit Metallionen zeigten, daß sie ein hohes Adsorptionsvermögen für Uranylionen und gute Stabilität gegen Chemikalien wie Säuren und Alkalien aufweisen. Es wurde auch gefunden, daß die Phosphongruppen enthaltenden Copolymeren recht effektive Adsorbentien für eine Vielzahl von Schwermetalionen wie Pb2+, Hg2+, Cd2+ und Cu2+ sind.
    Notes: Macroreticular copolymer beads were prepared by suspension polymerization of styrene, bis(2-chloroethyl) vinyl phosphonate (CEVP) and divinylbenzene (DVB) in the presence of toluene as diluent. The bis(2-chloroethyl) phosphonate groups on the bead surface were converted into phosphono groups by hydrolysis with dilute nitric acid. For the additional enrichment of phosphono groups, the copolymers were phosphorylated at the phenyl rings with phosphorus trichloride in the presence of aluminum chloride and hydrolyzed and oxidized with dilute nitrics acid. The investigations on metal ion chelation characteristics of the bead-type copolymers revealed that they have very high adsorptivity toward uranyl ions and good chemical resistance under acidic and alkaline media. It was also found that the phosphono group-containing copolymer beads are effective adsorbents for other heavy metal ions such as Pb2+, Hg2+, Cd2+, and Cu2+.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1992.051970110
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  • 88
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    Isocyanate reactions in and with N,N-dimethylformamide (1992)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 197 (1992), 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: Lösungen von Phenylisocyanat (I) in DMF wurden sowohl bei verschiedenen Temperaturen als auch in Gegenwart von Polyurethankatalysatoren und/oder 1,3-Diphenylharnstoff (II) gelagert. Die Reaktionsprodukte wurden mit Hilfe der HPLC quantifiziert. Neben der Hydrolyse von I zu II wird bei 20°C eine signifikante Reaktion von I mit II zu 1,3,5-Triphenylbiuret (III) beobachtet.Oberhalb 60°C reagiert I mit dem Lösungsmittel zu N,N-Dimethyl-N′-phenylformamidin (V). In DMF dissoziiert III bereits bei Temperaturen 〉 40°C zu I und II.
    Notes: Solutions of phenylisocyanate (I) in DMF were stored at different temperatures in the presence of both polyurethane catalysts and 1,3-diphenylurea (II). The reaction products were determined by HPLC. Beside the hydrolysis of I to II, a significant reaction of I with II to 1,3,5-triphenylbiuret (III) was observed at 20°C. Above 60°C, I reacted with the solvent to form N,N-dimethyl-N′-phenylformamidine (V). In DMF, III dissociated to I and II already at temperatures 〉40°C.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1992.051970111
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    Glass fiber-reinforced epoxy composites (1992)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 197 (1992), S. 141-147 
    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: Glasfaserverstärkte Epoxidlaminate wurden aus den Matrixharzen Tetraglycidyldiaminodiphenylmethan (TGDDM) und Tetraglycidylbis(o-toluidino)methan (TGMBT) unter Verwendung von Härtern wie 4,4′-Diaminodiphenylmethan (DDM), 4,4′-Diaminodiphenylsulfon (DDS) und Diethylentriamin (DETA) hergestellt. Die mechanischen und dielektrischen Eigenschaften sowie die Chemikalienresistenz der Laminate wurden untersucht. Die Zugabe eines Epoxyverstärkers (20 Gew.-%, bezogen auf das Matrixharz) ergab eine Verbesserung der mechanischen Eigenschaften.
    Notes: Glass fiber-reinforced epoxy composites were prepared from the matrix resins tetraglycidyl diaminodiphenylmethaneSystematic name: N,N,N′,N′-Tetrakis(2,3-epoxypropyl)-4,4′-diaminodiphenylmethane. (TGDDM) and tetraglycidyl bis(o-toluidino)-methaneSystematic name: N,N,N′,N′-Tetrakis(2,3-epoxypropyl)-4,4′-bis(o-toluidino)methane. (TGMBT) using various amines like 4,4′-diaminodiphenylmethane (DDM), 4,4′-diaminodiphenylsulfone (DDS) and diethylene triamine (DETA) as curing agents. The fabricated laminates were evaluated for their mechanical and dielectrical properties and chemical resistance. The composites prepared using an epoxy fortifier (20 phr) showed significant improvement in the mechanical properties.
    Additional Material: 3 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1992.051970112
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  • 90
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    Zur vernetzung dünner polymerschichten durch photolyse aromatischer bisazide (1992)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 197 (1992), S. 149-157 
    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: In 1 μm layers of different polymers containing 10 wt.-% 4,4′-diazidobiphenyl, the network formation under the influence of UV-irradiation was estimated by solvent treatment. The high activity of poly(glycidyl methacrylate) against the nitrenes formed is caused by its 1,2-epoxypropyl groups. As confirmed by IR-spectroscopy, the oxirane ring itself is not affected; NMR spectroscopic results indicate reactions between nitrenes and exocyclic CH2-groups.
    Notes: Die UV-Vernetzung in 1 μm-Schichten aus Polymeren verschiedener Konstitution, die 10 Gew.-% 4,4′-Diazidobiphenyl (DABP) enthalten, wird zeitabhängig anhand der reduzierten Schichtdicke nach Lösungsmittelbehandlung verglichen. Für die hohe Vernetzungsgeschwindigkeit von Polyglycidylmethacrylat mit den photolytisch gebildeten Bisnitrenen sind die 1,2-Epoxypropylgruppen verantwortlich. Der Oxiranring bleibt erhalten (IR-Spektroskopie). Wahrscheinlicher Reaktionsort ist die exocyclische CH2-Gruppe (13C-Festkörper-NMR-Spektroskopie).
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1992.051970113
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    Investigation of synthesis and light stability of polymeric azo dyes. I. Polymeric urethane-azo dyes (1992)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 197 (1992), S. 159-173 
    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: Ausgehend von 10 unterschiedlich 4′-substituierten 4-[N,N-dihydroxyethyl]aminoazobenzolen wurden durch Umsetzung mit Hexamethylendiisocyanat polymere Azofarbstoffe (M̄n 4200-10200) synthetisiert und die Substituentenabhängigkeit der spektralen Eigenschaften, der Redoxpotentiale und des Ausbleichverhaltens mit entsprechenden monomeren und dimeren Modellverbindungen verglichen. Die Ausbleichung erfolgt durch einen photooxidativen Prozeß. In der Reihenfolge monomerer 〉 dimerer 〉 polymerer Azofarbstoff sinkt die Lichtstabilität durch die Verringerung thermischer Desaktivierungsprozesse sowie durch einen möglichen intramolekularen Energietransfer.
    Notes: Starting from 10 different 4′-substituted 4-[N,N-dihydroxyethyl]aminoazobenzenes, polymeric urethane-azo dyes (M̄n 42000-10200) were prepared by reacting those with hexamethylene diisocyanate. The dependence of spectral properties, redox potentials and photofading behaviour on the kind of substitutents was determined and then compared with corresponding monomer and dimer model compounds. Photofading is caused by a photooxidative process. In the sequence of monomeric 〉 dimeric 〉 polymeric azo dyes, light stability decreases due to a diminution in thermal disactivation processes and in a possible intramolecular energy transfer.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1992.051970114
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  • 92
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    Announcements (1992)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 197 (1992), S. 207-208 
    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.1992.051970118
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  • 93
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    Electronic Resource
    Preparation of porous bead cellulose with technical grain size (1992)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 197 (1992), S. 201-206 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Bead cellulose, particle diameter 0.1 - 2.7 mm, was prepared from dispersions of viscose in chlorobenzene by applying the thermal sol-gel transition. Technical viscose containing modifiers Berol Visco 32, Berol Glyco 1540 and Kordamin V was used. The size of cellulose beads can be controlled by means of the amount of oleic acid in the dispersion medium. The optimal result was reached at 5 - 6 mg oleic acid in 90 ml chlorobenzene.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1992.051970117
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  • 94
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    Effect of electron radiation on dyed PET and PA 66 substrates (1992)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 197 (1992), S. 185-199 
    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: PET- und PA 66-Textilien wurden unter normalen Bedingungen mit verschiedenen Dispersionsfarbstoffen gefärbt. Die gefärbten Textilien wurden mit 180 kV Elektronenstrahlung bestrahlt. Es wurde beobachtet, daß, verglichen mit den unbestrahlten Materialien, zunehmende Strahlungsdosen zu einer Zunahme des Gesamtfarbabstandes dE führten. Diese Farbunterschiede werden hauptsächlich von zwei Reaktionen verursacht: Erstens von der reversiblen Bildung von Farbstoffradikalen, die (an Luft) wieder zu den Ausgangsfarbstoffen reoxidiert werden können und zweitens durch die irreversible Reaktion von Farbstoffmolekülen mit dem Faserpolymeren. Die zweite Reaktion ruft eine permanente Farbänderung des Textils hervor, die bei entsprechenden Bestrahlungsbedingungen klein gehalten werden kann. Die Entscheidung, ob diese Veränderung toleriert werden kann, hängt von der weiteren Verwendung des Textils ab.
    Notes: PET and PA 66 fabrics were dyed with different disperse dyes under regular conditions. The dyed fabrics were irradiated with 180 kV electron radiation. It was observed that increasing radiation doses led to increasing total color differences dE if compared to the unirradiated materials.These color differences are mainly caused by two types of reactions. First by the reversible formation of dye radicals, which can be reoxidized (in air) to the original dye molecules, and second by the irreversible reaction of dye molecules with the fiber polymer. The latter reaction causes a permanent change of the color of the fabric, which can be kept low with the proper irradiation conditions. The decision whether or not this change can be tolerated depends on the further use of the textile.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1992.051970116
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  • 95
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    Investigation of synthesis and light stability of polymeric azo dyes. II. Polymeric acrylate-azo dyesPart I cf.3. (1992)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 197 (1992), S. 175-184 
    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: Unterschiedlich 4′-substituierte 4-[N-Ethyl-N-(2-acryloyloxy)ethyl]aminoazobenzole dienten als Ausgangsmonomere für Homopolymerisationen und Copolymerisationen mit Styrol und Methylmethacrylat. Die Photobleichung der erhaltenen polymeren Azofarbstoffe (M̄ 4200-9000) wurde mittels einer Xenotest-Apparatur untersucht und mit den entsprechenden Monomeren verglichen. Es wird angenommen, daß die in der Reihenfolge monomerer  -  copolymerisierter  -  homopolymerisierter Azofarbstoff sinkende Photostabilität durch zunehmenden Energietransfer in der Matrix verursacht wird.
    Notes: Different 4′-substituted 4-[N-ethyl-N-(2-acryloyloxy)ethyl]aminoazobenzenes were used as starting monomers for homopolymerization and copolymerization reactions with styrene and methyl methacrylate. The photofading behaviour of the obtained polymeric azo dyes (M̄n 4200 - 9000) was investigated by means of a Xenotest device and compared with that of the corresponding monomers. The decreased photostability in the order monomer  -  copolymer  -  homopolymer was assumed to be caused by an increasing energy transfer in the matrix.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1992.051970115
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  • 96
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    Synthesis and exchange reactions of polymers containing reactive phthalimide groups (1992)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 198 (1992), S. 31-38 
    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: N-Methacryloyloxyphthalimid und N-Methacryloyloxytetrabromphthalimid wurden durch Reaktion von Methacrylsäure bzw. Methacryloylchlorid mit N-Hydroxyphthalimid bzw. N-Hydroxytetrabromphthalimid hergestellt und homopolymerisiert. Die Austauschreaktionen der Polymeren mit Hydroxy- und Amin-Verbindungen wurden untersucht.
    Notes: N-Methacryloyloxyphthalimide (NMPI) and N-methacryloyloxytetrabromophthalimide (NMTPI) were prepared by the reaction of methacrylic acid with N-hydroxy-phthalimide and N-hydroxytetrabromophthalimide, respectively. The resulting monomers were polymerized. The reactions of the resulting polymers with hydroxy and amine compounds have been studied.
    Additional Material: 4 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1992.051980103
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  • 97
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    Crystallization of poly(aryl ether ketones). 2. Double peak melting behavior of PEEKK (1992)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 198 (1992), S. 15-29 
    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 Tempern von Poly(etheretherketonketon) zwischen Glasübergangs- und Schmelztemperatur erzeugt normalerweise einen ausgeprägten Doppelschmelzpeak in der DSC-Kurve dieses Polymeren. Die eingehende Untersuchung dieses Doppelschmelzverhaltens in Abhängigkeit von Temperbedingungen und experimentellen Parametern zeigt, daß die Kristallisation als ein in zwei Stufen mit unterschiedlichen Zeitskalen ablaufender Prozeß beschrieben werden kann. Eine Rekristallisation als Ursache des Doppelpeaks kann widerlegt werden.
    Notes: Annealing poly(ether ether ketone ketone) (PEEKK) between glass transition and melting temperature generally results in a pronounced double peak melting behavior as obtained by DSC. Detailed investigations of the dependence of this double peak melting behavior on annealing conditions and experimental parameters clearly reveal that the crystallization can be described by a two-stage process occurring on different time scales. A recrystallization model as origin for the double peak melting curves can be disproved.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1992.051980102
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  • 98
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    Hydroformylation of nitrile rubber and its characterization (1992)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 198 (1992), S. 1-14 
    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: Nitrilkautschuk (NBR) wurde mit trans-Chlorcarbonylbis(tripheny1phosphin)rhodium(1) [trans-RhCI(CO)(PPh3)2] und Hydridocarbonyltris(triphenylphosphin)rhodium(1) [RhH (CO)(PPh3)3] als Katalysatoren in homogener Lösung selektiv hydroformyliert. Bei der Hydroformylierung von NBR mit 40 mol-% Acrylnitril bei 363 K, 5,6 MPa Gasdruck (CO:H2 = 1:1) und mit 0,43 mmol Katalysator werden mit trans-RhCl(CO)(PPh3)2 25% und mit RhH (CO)(PPh3)3 30% Umsatz erreicht. Beide Reaktionen sind bezüglich der Olefin- und Katalysatorkonzentration pseudo-erster Ordnung. Mit RhH (CO)(PPh3)3 wird eine höhere Reaktionsgeschwindigkeit erhalten. Die IR- und NMR-spektroskopische Charakterisierung der Produkte zeigt, daß sowohl die 1,4- als auch die 1,2-Butadieneinheiten hydroformyliert werden. Mit steigendem Aldehydgruppengehalt sinkt die Grenzviskositatszahl [q] und steigt die Glastemperatur. Bei hoheren Hydroformylierungsgraden wird Gelbildung beobachtet.
    Notes: Selective homogeneous catalytic hydroformylation of nitrile rubber (NBR) has been carried out in presence of trans-chlorocarbonylbis(triphenylphosphine)rhodium(I) [trans-RhCl(CO)(PPh3)3] and hydridocarbonyltris(triphenylphosphine)rhodium(I) [RhH(CO)(PPh3)3] as catalysts. At 363 K, under 5.6 MPa pressure (CO:H2 = 1:1) in presence of 0.43 mmol/l catalyst, the amount of hydroformylation is 25% in the case of trans-RhCl(CO)(PPh3)2 and 30% in the case of RhH (CO)(PPh3)3 for NBR with 40 mol-% acrylonitrile. Reaction kinetics suggest that both the reactions are pseudo-first order with respect to olefinic substrate and catalyst concentration. The rate of the reaction is higher in the case of RhH(CO)(PPh3)3. The characterization of the products by IR and NMR spectroscopy shows the formation of internal aldehyde groups from 1,4-units and terminal branched aldehyde groups from 1,2-units of the copolymer. Measurements on intrinsic viscosity [η] and glass transition temperature (Tg) suggest a decrease in [η] and an increase in Tg with the degree of formyl functionalization. Gel formation has been observed at higher degree of hydroformylation.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1992.051980101
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  • 99
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    Bonding of rhenium(V) to diethylenetriaminepentaacetate functional groups of a polymethacrylate support (1992)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 198 (1992), S. 61-70 
    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 Rhenium in einer polymeren Methacrylat-Matrix mit funktionellen Diethylentriaminpentaessigsäure-Gruppen wurde untersucht. Es werden diamagnetische Komplexe gebildet, wobei Rhenium in einer heterogenen Koordinationssphäre gebunden wird, bestehend aus Chlor und mehrfach gebundenem Sauerstoffsowie Carboxygruppen, die als einzige funktionelle Gruppe des polymeren Trägers als Ligand des Metallatoms wirken. Die Rhenium-Komplexe wurden durch IR- und UV-VIS-Spektroskopie sowie durch Messung ihrer magnetischen Momente charakterisiert.
    Notes: The bonding of rhenium to diethylenetriaminepentaacetic acid functional groups of a polymeric methacrylate matrix was studied. Diamagnetic complexes were formed of Re(V) with the heterogeneous coordination sphere containing atoms of chlorine and multiply bonded oxygen in addition to carboxylic groups, which are the only groups of the polymeric support functioning as ligands in the bonding to the metal. The rhenium complexes were examined by IR and UV-VIS spectroscopy and by magnetic moment measurements.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1992.051980106
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  • 100
    Electronic Resource
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    m-Bromophenolic epoxy resins for electronic packaging (1992)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 198 (1992), S. 51-60 
    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: Meta-halogenierte Phenole sind bekanntermaßen chemisch und thermisch stabiler als ihre ortho- oder para-halogenierten Analoga. Die Verwendung eines reaktiven Zwischenproduktes, hergestellt durch Bromierung von 2,4,6-Trimethylphenol, als Alkylierungsmittel für den Einbau der stabilen m-Bromphenol-Einheit in verschiedene organische Substanzen und Polymere wird beschrieben. Bei der Anwendung als Verkapselungsmaterialien für elektronische Bauteile zeigten sich Epoxid-Derivate von Novolaken mit m-Bromphenol-Einheiten bezüglich hydrolytischer und thermischer Stabilität den konventionellen Tetrabrombisphenol-A-Epoxidharzen, die ortho- und para-bromiert sind, überlegen. Die m-Bromphenolgruppe verbessert die Bauteilzuverlässigkeit bei gleichzeitiger Erfüllung der Anforderungen an das Brandverhalten.
    Notes: Meta-halogenated phenols are generally known to be more chemically and thermally stable than their ortho- or para-halogenated counterparts. A reactive intermediate, produced by the bromination of 2,4,6-trimethylphenol is being used as an alkylating agent to incorporate this stable m-bromophenol moiety into varieties of organic compounds and polymers. In electronic encapsulation applications, epoxy derivatives of novolacs containing m-bromophenol have exhibited superior hydrolytic and thermal stability as compared with the conventional tetrabromo bisphenol-A epoxies which are ortho-brominated phenolics. The m-bromophenol moiety contributes to the extended device reliability while meeting flame retardency requirements as well.
    Additional Material: 5 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1992.051980105
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