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  • 1
    Electronic Resource
    Electronic Resource
    On the structure and stability of nanoscale materials: a two-dimensional model (1995)
    Springer
    The European physical journal 97 (1995), S. 503-510 
    Details
    ISSN: 1434-6036
    Keywords: 61.55.F
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract We have investigated numerically using the Metropolis Monte Carlo algorithm two-dimensional systems of about 3000 classical particles interacting via a Lennard-Jones potential and being subjected to periodic boundary conditions. In this model we consider metastable structures of small crystalline grains which are randomly oriented relative to each other and which are interconnected by a network of boundaries. The atomic structure within the grains being composed of about 500 atoms each is a nearly ideal triangular lattice. The network of boundaries however has a highly defective structure which is determined by the boundary conditions enforced by the crystalline grains. It is the objective of our work to develop a conceptually simple model for nanocrystalline materials, which can be used for a qualitative description of their complex properties. The main ingredient of the model is its property to relax into a metastable state consisting of intrinsically well ordered crystalline grains connected by a highly defective intergranular component. For that state we compute the static structure factor and the pair correlation function.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01322431
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  • 2
    Electronic Resource
    Electronic Resource
    Calcium dynamics in cardiac myocytes as a target of dichloromethane cardiotoxicity (1996)
    Springer
    Archives of toxicology 70 (1996), S. 158-163 
    Details
    ISSN: 1432-0738
    Keywords: Key words Dichloromethane ; Cardiotoxicity ; [Ca2+]i transients ; Myocardial contraction ; Cardiac arrhythmia
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  The purpose of the present study was to determine if cardiac actions of dichloromethane (DCM) in vivo correlate with in vitro alterations of Ca2+ dynamics in cardiac myocytes. Neonatal rat ventricular myocytes were obtained from 2- to 4-day-old rats, and electrically induced fluctuations of cytosolic free Ca2+ concentration ([Ca2+]i) in single cardiomyocytes were investigated using spectrofluorometric analysis of fura-2-[Ca2+]i binding. In cultured myocytes, cumulative exposure to 0.64–40.96 mM DCM resulted in a concentration-dependent and reversible decrease in the magnitude of [Ca2+]i transients with IC10 and IC50 values of 7.98 and 18.82 mM, respectively. Total inhibition of [Ca2+]i transients and cessation of beating were observed at 40.96 mM DCM. Suffusion with DCM for 40 min did not cause morphological alterations of the myocytes. In a urethane-anesthetized rat model, left ventricular pressure was measured by introducing a tip catheter via the carotid artery into the left ventricle, the ECG was recorded by two needle electrodes applied subcutaneously to the chest wall, and arterial pressure was measured via the femoral artery. Oral administration of 3.1–12.4 mmol DCM/kg resulted in DCM blood concentrations between 1.0 and 1.6 mM, accompanied by a dose-dependent decrease in contractile force and heart rate without influencing blood pressure and ECG tracings. Moreover, DCM treatment provided significant protection against arrhythmia development due to CaCl2-infusion. In spite of the slight discrepancy between DCM blood concentrations and in vitro concentrations of DCM for [Ca2+]i transient inhibition, present data are consistent with the view that cardiac effects after DCM exposure are mediated by alterations of Ca2+ dynamics during excitation-contraction coupling.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002040050255
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  • 3
    Electronic Resource
    Electronic Resource
    Cardiotoxicity of chlorodibromomethane and trichloromethane in rats and isolated rat cardiac myocytes (1997)
    Springer
    Archives of toxicology 71 (1997), S. 766-777 
    Details
    ISSN: 1432-0738
    Keywords: Key words Chlorodibromomethane ; Trichloromethane ; Cardiotoxicity ; [Ca2+] i transients ; Catecholamine
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The cardiovascular effects were investigated after acute and subacute treatment with chlorodibromomethane (CDBM; 0.4 to 3.2 mmol/kg p.o.), trichloromethane (TCM; 0.31 and 1.25 mmol/kg p.o.) and mixtures of CDBM and TCM (acute, 0.8 mmol CDBM/kg + 1.25 mmol TCM/kg p.o.; subacute, 0.4 mmol CDBM/kg+0.31 mmol TCM/kg p.o.) in conscious and urethane anaesthetized male Wistar rats (n=610 per treatment). Furthermore it was observed whether cardiovascular responses were modified in CDBM or TCM treated rats after administration of exogenous catecholamines (epinephrine, 1 μg/kg; norepinephrine, 2 μg/kg) and underpinned with in vitro alterations of Ca2+ dynamics in cardiac myocytes. The present findings demonstrated that single and subacute oral administration of CDBM or TCM and mixtures of CDBM and TCM resulted in arrhythmogenic and negative chronotropic and dromotropic effects in conscious and urethane anaesthetized rats. The atrioventricular conduction time and the intraventricular extension time were extended. A slight shortening of the repolarization velocity was observed. The myocardial contractility was depressed and the heart was sensitized to the arrhythmogenic effects of epinephrine. After catecholamine injection the adrenergic cardiovascular responses in urethane anesthetized rats were modified: increased hypertensive epinephrine and norepinephrine action as well as augmentation of negative chronotropic and negative dromotropic cardiac effects of catecholamines were observed. The positive inotropic adrenergic response was diminished. The present in vivo findings, myocardial depression after acute CDBM treatment, as determined by different indices of contractility, correlate well with the observed inhibitory actions of CDBM on Ca2+ dynamics in isolated cardiac myocytes. All cardiovascular alterations found after CDBM or TCM treatment were not intensified after treatment with mixtures of CDBM and TCM. The effects observed were distinctly stronger after TCM (1.25 and 0.31 mmol/kg) treatment compared to CDBM (0.8 and 0.4 mmol/kg) treatment.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002040050459
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  • 4
    Electronic Resource
    Electronic Resource
    Radiolysis of polymers of chlorine methacrylates (1988)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 26 (1988), S. 2669-2681 
    Details
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Polymers of α-chloroacrylate (MCA), 1-chloroethyl methacrylate (1CEMA), 2-chloroethyl methacrylate (2CEMA), 2,2,2-trichloroethyl methacrylate (trCEMA) and 1,2,2,2-tetrachloroethyl methacrylate (teCEMA) were γ-irradiated at 77 K. The primary radicals were generated by the abstraction of chlorine. They decay or change into chain end radicals upon warming up to room temperature.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pola.1988.080261004
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  • 5
    Electronic Resource
    Electronic Resource
    Radiation induced radical reactions in poly(chloroalkyl methacrylate)s/triallylisocyanurate mixtures (1989)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 27 (1989), S. 1589-1598 
    Details
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Radical generation after γ-irradiation at 77 K and radical reactions during temperature increase are discussed for the polymers poly(2-chloroethyl methacrylate) and poly(1,2,2,2-tetrachloroethyl methacrylate), mixed with triallylisocyanurate (TAIC). After the radiation interaction radicals are generated in the ester alkyl side groups of the polymer by chlorine abstraction in both polymer/TAIC mixtures. Radical transfer to TAIC occurs during temperature increase to produce allyl radicals. Hence, the high radiation sensitivity of chlorine-containing polymers is combined with the reactivity of allyl radicals of TAIC in such polymer-TAIC mixtures.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pola.1989.080270510
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  • 6
    Electronic Resource
    Electronic Resource
    EPR-Untersuchungen γ-bestrahlter chlorsubstituierter Poly(methacrylate) (1987)
    Weinheim : Wiley-Blackwell
    Acta Polymerica 38 (1987), S. 114-119 
    Details
    ISSN: 0323-7648
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: γ-radiolysis of poly(methyl methacrylate) (PMMA) and chlorosubstituted poly(methacrylates) gives radicals with comparable nine-line-EPR spectra. The transformations of the molecules were discussed in light of the quantitative differences in the accumulation processes. EPR-spectra at liquid helium temperatures confirm the hypothesis of allyl radical accumulation in PMMA.
    Notes: Die im Poly(methylmethacrylat) (PMMA) und in chlorsubstituierten Poly(methacrylaten) radiolytisch erzeugten Radikale ergeben ähnliche EPR-Neunlinienspektren. Molekülumwandlungen zur Deutung der quantitativ unterschiedlichen Akkumulationsprozesse werden diskutiert. EPR-Spektren bei Heliumtemperaturen bestätigen die Hypothese der Akkumulation von Allylradikalen im PMMA.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/actp.1987.010380204
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  • 7
    Electronic Resource
    Electronic Resource
    Morphologische Besonderheiten polymerer Mehrkomponentensysteme auf der Basis von Dithiolen und Diisocyanaten (1979)
    Weinheim : Wiley-Blackwell
    Acta Polymerica 30 (1979), S. 496-502 
    Details
    ISSN: 0323-7648
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Polyurethanes obtained by reacting mercapto-terminated oligobutadienes, decanedithiol and diisocyanate were investigated by electron microscopy and x-ray scattering. The dependence of the morphological structure on the content of short-chain dithiol is discussed. Heterogeneities in micro- and macroregions were observed, which are caused by crystalline regions and phase separation in chemically different blocks.
    Notes: Polyurethane auf der Basis von mercapto-terminierten Oligobutadienen, Decandithiol und Diisocyanat werden mittels Elektronenmikroskopie und Röntgenstreuung untersucht. Ihre morphologischen Besonderheiten werden in Abhängigkeit vom Gehalt an Kurzkettendithiol diskutiert. Es treten Heterogenitäten im Mikro- und Makrobereich auf, die durch kristalline Bereiche und Phasentrennung in chemisch unterschiedliche Blöcke bedingt sind.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/actp.1979.010300807
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  • 8
    Electronic Resource
    Electronic Resource
    Characterization of ion beam damage effects in poly(1,2,2,2-tetrachloroethyl methacrylate) by ESCA (1987)
    Weinheim : Wiley-Blackwell
    Acta Polymerica 38 (1987), S. 638-639 
    Details
    ISSN: 0323-7648
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/actp.1987.010381111
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  • 9
    Electronic Resource
    Electronic Resource
    Experimentelle prüfung der beziehungen zwischen mechanischen konstanten von gelen für dehnung bei konstantem quellungsgrade einerseits, bei konstantem partialdruck des quellungsmittels andererseitsHerrn Prof. Dr. R. SIGNER zum 60. Geburtstag gewidmet (1963)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 62 (1963), S. 40-48 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: The YOUNG's modulus E′ and the POISSON number μ′ of a swollen gel sample, stretched in an embedding fluid of constant activity, are different from the YOUNG's modulus E and the POISSON number μ of the same gel sample stretched at constant mass of the swelling agent in the sample. A relation between the four elastic constants derived recently was confirmed by experiment.
    Notes: Zwei verschiedene Bedingungen, unter denen eine gequollene Folie elastisch verformt werden kann, sind: 1. Dehnung bei konstanter Zusammensetzung, insbesondere bei konstantem Gehalt des Gelfadens an Quellungsmittel und 2. Streckung bei konstantem Partialdruck des Quellungsmittels. Die Elastizitätsmodule E, E′ und die POISSONschen Zahlen μ, μ′ für diese beiden Dehnungsbedingungen werden definiert und experimentell festgestellt. Eine quantitative beziehung zwischen diesen vier Größen, die in einer früheren Arbeit hergeleitet worden war, konnte experimentell bestätigt werden.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1963.020620105
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  • 10
    Electronic Resource
    Electronic Resource
    Strahlungsinitiierter Kettenabbau von Homo- und Copolymeren des 1,2,2,2-Tetrachlorethyl- und Methylmethacrylats (1988)
    Weinheim : Wiley-Blackwell
    Acta Polymerica 39 (1988), S. 405-406 
    Details
    ISSN: 0323-7648
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/actp.1988.010390720
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