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  • 1985-1989  (31)
  • Chemistry  (24)
  • Life and Medical Sciences  (7)
  • General Chemistry  (2)
  • 1
    Electronic Resource
    Electronic Resource
    Capillary gas chromatography/mass spectrometry of cholesteryl esters with negative ammonia chemical ionization (1987)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 14 (1987), S. 131-140 
    Details
    ISSN: 0887-6134
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Mixtures of both synthetic and naturally occurring (human plasma) cholesteryl esters have been examined by capillary gas chromatography/mass spectrometry (GC/MS). A magnetic sector mass spectrometer was used and a variety of ionization modes were assessed with a view to obtaining structural information on intact cholesteryl esters. By employing ammonia as reagent gas, with negative ion scanning, spectra were produced from which the nature of steryl and fatty acyl moieties could be readily deduced. Analyses were performed at an ion source temperature of 300°C in order to maintain the integrity of the gas chromatographic profile. The technique described is of general use for the GC/MS analysis of steryl esters, particularly in conjunction with magnetic sector instruments.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bms.1200140307
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  • 2
    Electronic Resource
    Electronic Resource
    Fertilization and aqueous development of the puerto rican terrestrial-breeding frog, Eleutherodactylus coqui (1987)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 193 (1987), S. 217-224 
    Details
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The Puerto Rican tree frog, Eleutherodactylus coqui, has internal fertilization and direct development on land. In light of these reproductive adaptations, the events of fertilization and early development were studied. Cytological examination of just-fertilized eggs showed that sperm entry is restricted to about 10% of the surface of these large, yolky eggs, and all nuclear events of the first cell cycle occur near the animal pole. Although the oocytes have cortical granules, a number of polyspermic fertilizations were found. One clutch consisted of eggs with a high frequency of polyspermy and of normal development. This raises the possibility that normal development can occur despite multiple sperm entry, a situation not found in other anuran amphibians. With respect to saline requirements, the sperm and the embryo are similar to those in amphibians with external fertilization and aqueous development. Sperm motility was high in low-tonicity conditions, and the normally terrestrial embryo could develop completely from a fertilized egg to a froglet in a low-tonicity aqueous solution.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jmor.1051930208
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Grain sorghum stillage recycling: Effect on ethanol yield and stillage quality (1985)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 27 (1985), S. 1735-1738 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Stillage obtained from ethanol production of grain sorghum was separated into two fractions: thin stillage and wet solids. A portion of the thin stillage was recycled as cooking water in subsequent fermentation runs using both bench- and full-scale ethanol production plants. When thin stillage replaced 50-75% of the cooking water, large increases occurred in solids content, COD, and EC of the resulting thin stillage. It was found that while the volume of thin stillage requiring treatment or disposal was reduced, there was little reduction in the total pollutant load. Stillage rcycling had little effect on the quality of the stillage wet solids fraction. At the high levels of stillage recycle used, ethanol yield was reduced after three to five runs of consecutive recycling.
    Additional Material: 5 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260271217
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  • 4
    Electronic Resource
    Electronic Resource
    Dielectric properties of an epoxy resin and its composite I. Moisture effects on dipole relaxation (1986)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 31 (1986), S. 1771-1784 
    Details
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Dipole relaxation dielectric loss behavior of a fiberglass-epoxy composite has been studied as a function of moisture uptake. A single widely distributed loss peak, centered at -16°C for 10 kHz measurement, is observed in the dry composite. Very low moisture concentrations (〈0.1%) interact with the composite, through either dipole pairing or by inducing chemical changes, to decrease loss intensity. At moisture concentrations from 0.1 to 1.4%, loss peak intensity generally increases with moisture uptake. Over this moisture concentration range water dipoles presumably relax in phase with the epoxy segments or side groups upon which they adsorb. Arrhenius relaxation activation energy decreases, and improved loss peak definition at increasing moisture concentrations is interpreted as indicating resin plasticization by adsorbed moisture. At moisture concentrations above 1.4%, the appearance of a second loss peak suggests formation of a new colloidal or weakly adsorbed moisture phase, as well as the saturation of primary adsorption sites.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1986.070310622
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  • 5
    Electronic Resource
    Electronic Resource
    Dielectric properties of an epoxy resin and its composite II. Solvent effects on dipole relaxation (1987)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 33 (1987), S. 2293-2303 
    Details
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Dipole relaxation dielectric loss behavior of a fiberglass-epoxy composite has been studied following submersion in polar and nonpolar organic solvents as well as in acidic and basic aqueous solutions. Certain adsorbed organic solvents, such as 1,2-dichloroethane, had little influence on the epoxy relaxation behavior. Other solvents, including chloroform, increased the composite relaxation intensity and shifted the temperature-frequency region over which the relaxation occurred. Both the amount of solvent uptake and the degree of interaction of solvent molecules with epoxy polar functional groups appear to control the amount of relaxation behavior perturbation. Arrhenius activation energies for relaxation were lowered by solvent uptake from the dry composite value of 18 kcal/M to between 6 and 16 kcal/M, depending on the solvent adsorbed. Submersion in methanol and chloroform sharply increased the direct current conductivity of the composite. Two molar acidic and basic solutions had little influence on composite dipole relaxation behavior other than the well known behavior associated with moisture uptake.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1987.070330703
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  • 6
    Electronic Resource
    Electronic Resource
    LCEC determination of the copper protein ceruloplasmin in human serum at a polyaniline chemically modified electrode (1989)
    Weinheim : Wiley-Blackwell
    Electroanalysis 1 (1989), S. 133-140 
    Details
    ISSN: 1040-0397
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A chemically modified electrode (CME) for use in the amperometric detection of the copper protein ceruloplasmin was constructed by electropolymerizing a polyaniline coating onto glassy carbon. The resultant CME, used in liquid chromatographic detection, gave an electrocatalytic response for ceruloplasmin reduction that could be employed directly by itself or could be greatly enhanced by the addition of Fe2+ to the mobile phase. Optimum detection was achieved at an applied potential of -0.10 V vs. Ag/AgCl and with 1 mM Fe2+ in the mobile phase. The detection limit obtained under these conditions was 2 pmol injected, and the response was linear for concentrations at least 2 orders of magnitude higher. The CME retained more than 90% of its initial response to ceruloplasmin over 30 hours of continuous exposure to the chromatographic flowstream. In practice, the liquid chromatography CME response was sensitive and selective enough to permit quantitation of physiologically relevant levels of ceruloplasmin in human serum with no sample pretreatment other than preinjection filtration.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/elan.1140010208
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  • 7
    Electronic Resource
    Electronic Resource
    Preconcentration and determination of lead(II) at crown ether and cryptand containing chemically modified electrodes (1989)
    Weinheim : Wiley-Blackwell
    Electroanalysis 1 (1989), S. 13-21 
    Details
    ISSN: 1040-0397
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Chemically modified electrodes (CMEs) containing incorporated crown ether and cryptand ligands as modifiers were evaluated for their ability to preconcentrate metal cations prior to quantitation by conventional voltammetric methods. Stable CMEs were formed for 18-crown-6, dibenzo-18-crown-6, poly(dibenzo-18-crown-6), dibenzo-24-crown-8, and 2.2.2-cryptand by mixing the desired amount of the ligand into carbon paste. The resulting electrodes exhibited complexing capabilities that were similar to those of the free ligands. In particular, the CMEs were very reactive toward Pb2+ and Hg2+. Pb2+ uptake was sufficiently strong that a detection limit of 1 μM was obtained following a 20-sec exposure to the sample and transfer to a blank electrolysis solution for differential pulse voltammetric analysis. Accurate quantitation of micromolar levels of Pb in water and urine reference standards was achieved at the CMEs by means of a simple procedure requiring minimal sample preparation. Finally, the analytical characteristics of CME preconcentration were directly compared to those of the electrodeposition approach ordinarily employed in stripping voltammetry.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/elan.1140010104
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  • 8
    Electronic Resource
    Electronic Resource
    Metastable ions arising from pseudomolecular [M — H]- ions produced by fast-atom bombardment negative-ion mass spectrometry of ecdysteroids (1989)
    New York, NY : Wiley-Blackwell
    Rapid Communications in Mass Spectrometry 3 (1989), S. 352-355 
    Details
    ISSN: 0951-4198
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: Metastable ions arising from pseudomolecular [M — H]- ions produced by fast-atom bombardment negative-ion mass spectrometry of a range of free ecdysteroids, ecdysteroid conjugates and polar metabolites were investigated by means of linked scanning at constant B/E. Free ecdysteroids displayed daughter-ion spectra which allow 20-hydroxyecdysteroids and ecdysteroids lacking C-20 hydroxylation to be readily distinguished. The ejection of acetic acid from acetylated ecdysteroids was also readily detectable. Characteristic metastable-ion decomposition of ecdysteroid acids was not observed, presumably as a result of charge localization. High-mass daughter ions were also lacking in the case of phosphate conjugates.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/rcm.1290031010
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  • 9
    Electronic Resource
    Electronic Resource
    Heterogeneity of the changes in cytoplasmic pH upon serum stimulation of quiescent fibroblasts (1989)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 141 (1989), S. 410-419 
    Details
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Addition of mitogens to quiescent cells results in rapid ionic changes in the cytoplasm, including pH. We studied the changes in cytoplasmic pH in single Swiss 3T3 cells upon serum stimulation using fluorescence ratio imaging microscopy. Quiescence was attained using two approaches, serum deprivation of subconfluent cells and confluence. All measurements were made in the presence of bicarbonate and the absence of other organic buffers. We also used BCECF coupled to dextran to avoid several artifacts associated with using BCECF-AM, including leakage and phototoxicity. Analysis of the changes in cytoplasmic pH demonstrated a dramatic heterogeneity in the responses of single cells. There were six basic classes of responses, (1) a fast alkalinization, reaching a maximum pH in ∼2-5 min; (2) a slow alkalinization, reaching a maximum pH in 10-20 min; (3) a very slow alkalinization, not reaching a plateau pH within the measurement time; (4) no apparent change in pH during the measurement time; (5) an early transient acidification, followed by either a fast or slow alkalinization; and (6) an acidification, followed by alkalinization and then by a decrease to some intermediate pH. Subconfluent cells exhibited greater heterogeneity in response than confluent cells, with no single dominant class of response. The dominant (55%) response for confluent cells was a gradual alkalinization of ∼0.01 pH units/min. A larger proportion (52%) of subconfluent cells exhibited an early transient acidification compared to confluent cells (7%). A significant proportion of both types of cells (23% subconfluent, 36% confluent) exhibited no change in cytoplasmic pH upon stimulation. In general, the kinetics of changes in cytoplasmic pH were significantly different from the published results with population averaging methods.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcp.1041410223
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  • 10
    Electronic Resource
    Electronic Resource
    Expression of epidermal growth factor receptor and associated glycoprotein on cultured human brain tumor cells (1986)
    New York, N.Y. : Wiley-Blackwell
    Journal of Cellular Biochemistry 32 (1986), S. 1-10 
    Details
    ISSN: 0730-2312
    Keywords: epidermal growth factor ; brain tumors ; cell surface glycoproteins ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: The expression of epidermal growth factor (EGF-R) in normal glial and glioma cells grown in culture was examined by using several independent assays. Immunoprecipitation with the monoclonal antibody R1 of extracts from metabolically labeled glial and glioma cells revealed a protein of Mr ∼ 170,000, with a migration in sodium dodecyl sulfate-polyacrylamide gels identical to the EGR-R of A431 epidermal carcinoma cells. Furthermore, in the majority of glioma extracts, a protein of Mr ∼ 190,000 was specifically immunoprecipitated by this antibody. Similar results were obtained by immunoblotting with a second antibody directed against a synthetic peptide in the sequence of the V-erb-B oncogene. In cell lines expressing both proteins, each was specifically phosphorylated on tyrosine in immune complex kinase assays. The majority of glioma cells bound between 40,000 to 80,000 125I-labeled epidermal growth factor molecules per cell. These results suggest that the expression of EGF-R is common in cultured human glioma cells. In addition, a structurally related protein, is expressed in some of these cells.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcb.240320102
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