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  • 1
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 9 (1975), S. 127-142 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: A thermodynamic approach to the problem of platelet adsorption out of a suspension on to a smooth and homogeneous solid surface is developed. The interfacial tension values required may be estimated from contact angle data by means of an equation of state relation. According to the thermodynamic approach the functional dependence of platelet adsorption on surface tension of the solid differs according to whether the surface tension of the platelets is smaller or larger than the surface tension of the liquid in which they are suspended. The implications of this thermodynamic approach in situations where plasma proteins are present and the biomaterials surfaces may be heterogeneous and rough are discussed. Previous analyses using the critical surface tension of wetting and other surface-related parameters are compared with the thermodynamic analysis given here.
    Additional Material: 4 Ill.
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  • 2
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Chemistry Edition 15 (1977), S. 2229-2238 
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A new facile route to linear, high molecular weight D2-meta-decacarborane-siloxanes was developed based on the condensation reaction between bisureidosilanes and carborane disilanol. By using NMR to monitor the reaction stoichiometry, polymers with molecular weight ≥250,000 have been prepared. Moreover, because of the mild reaction conditions, structural modifications of the polymer backbone have been readily achieved. These linear, high molecular weight polymers overcome the fabrication difficulties encountered in previously prepared D2-polymers.
    Additional Material: 2 Ill.
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  • 3
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 14 (1979), S. 543-549 
    ISSN: 0030-493X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: From deuterium labelling experiments it was concluded that metastable molecular ions of ethyl methyl sulfide lose a methyl radical with the formation of both [CH3S=CH2]+ amd [CH3CH=SH]+· The fragmentation reactions of metastable ions generated with these structure are losses of C2H2, H2S and CH4. These reactoins and the preceding isomerizations have also been studied by means of deuterium labelling. From the results it is concluded that the three fragmentation reactions most probably occur from ions with a C—C—S skeleton. Appearance energy measurements for ions generated with the two structures above and all give rise to the same ΔHf value for these three isomeric forms. Ab initio molecular orbitals calculations confirm that these three ions fortuitously have very similar heats of formation. A potential energy diagram rationalizing the isomerizations and the principal fragmentation reaction is presented.
    Additional Material: 1 Ill.
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  • 4
    ISSN: 0306-042X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The preparation of a series of N-nitrosamines for carcinogenicity studies presented an opportunity to study mass spectral fragmentation schemes in detail. Condensed spectra are listed for 146 N-nitrosamines of widely differing structures, including nitroso derivatives of commercial drugs and insecticides. Aliphatic nitrosamines were generally characterized by molecular ions and loss of OH. Subsequent fragmentation via α-cleavage is similar to that of aliphatic amines. The loss of OH is believed to result in a cyclic ion. Substituted aliphatic nitrosamines varied in fragmentation schemes with structure and position of the substituent groups. However, most showed α-cleavage at some point in fragmentation. When substituted with aromatic groups, prominent peaks due to the aromatic moiety were observed. The alicyclic nitrosamines showed losses of NO, NOH and OH and subsequent α-cleavages. Nitrosamides were characterized by rupture of the carbonyl to nitrogen bond. Spectra of substituted ureas usually showed charge retention by the carbonyl fragment, while carbamate esters showed ions from both fragments.
    Additional Material: 5 Ill.
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  • 5
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Some results are reported on the linear viscoelastic properties of polybutadienes with narrow-molecular-weight distributions. The zero shear viscosity η0 varies as M3.4 in the linear samples, and viscosity enhancement is found in star-branched samples with long arms, in good agreement with results reported earlier by Kraus and Gruver. The temperature coefficient of viscosity appears to be slightly larger in stars when the arms become long. The steady state recoverable compliance J0e is 2.1 × 10 -7 cm2/dyn in linear samples of high molecular weight, but it increases to values as much as 10 times larger in the stars. The plateau modulus G0N, obtained from a composite curve for the linear samples, is 1.32 × 107 dyn/cm2. The terminal relaxation spectrum of the stars is too broad to allow an evaluation of plateau modulus.
    Additional Material: 11 Ill.
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  • 6
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 444 (1978), S. 21-29 
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Chemical Reactions in Molten Salts. XVIII. Synthesis of Methyltin Trichloride, Ch3SnCl3A process for the synthesis of CH3SnCl3 by reaction of molten SnCl2 and CH2Cl infused salts is described. Out of the systems investigated with NaCl, KCl, AlCl3, ZnCl2, KZnCl3, LiAlCl4, NaAlCl4, KAlCl4, and CuAlCl4, the systems with NaAlCl4 and NaAlCl4/KAlCl4 proved best. We measured the space-time-yield (RZA) as a function of the salts admixed to SnCl2 as well as a function of the reaction temperatur, gasification, and inlet rate of CH3Cl respectively. The optimum reaction conditions are investigated and the system SnCl2//NaAlCl4 is described.
    Notes: Ein Verfahren zur Synthese von CH3SnCl3 durch Reaktion von geschmolzenem SnCl2 mit CH3Cl in Salzschmelzen wird beschrieben. Von den untersuchten Systemen mit NaCl, KCl, AlCl3, ZnCl2, KZnCl3, LiAlCl4, NaAlCl4, KAlCl4 und CuAlCl4 erwiesen sich als besonders vorteilhaft NaAlCl4 und NaAlCl4/KAlCl4. Gemessen wurde die Abhängigkeit der Raum-Zeit-Ausbeute (RZA) vom Zusatz von Fremdsalz zum SnCl2 sowie von der Reaktions-Temperatur, der Begasung und der Einleitgeschwindigkeit von CH3Cl, und die optimalen Versuchsbedingungen bestimmt. Das System SnCl2/NaAlCl4 wird beschrieben.
    Additional Material: 5 Ill.
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  • 7
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 416 (1975), S. 306-310 
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Substitution Reactions with Sulphur DiimidesSubstituted sulphur diimides are obtained by the reactions of (CH3)3Si—N=S=N—Si(CH3)3 with CH3SO2Cl and CCl3SCl or with P2O3F4 and (CH3)3Si—N=S=N—SN(CH3)2. S4N4 reacts with (CH3)2Si[N(CH3)2]2 to from (CH3)2Si(N(CH3)2)—N=S=N—SN(CH3)2 while S3N2Cl2 yields (CH3)2Si(Cl)—N=S=N—SN(CH3)2.It is possible to substitute the chlorine atom by diethylamine in the last compound.The new compounds are intermediates for the syntheses of cyclic sulphur-nitrogen compounds. They were characterized by mass-, ir-, 1H-nmr spectra and elemental analysis.
    Notes: Substituierte Schwefeldiimide werden durch Umsetzung von (CH3)3Si—N=S=N—Si(CH3)2 mit CH3SO2Cl und CCl3SCl oder von P2O3F4 mit (CH3)3Si—N=S=N—SN(CH3)2 dargestellt. S4N4 bzw. S3N2Cl2 reagieren mit (CH3)2Si[N(CH3)2]2 zu (CH3)2Si(N(CH3) 2)—N=S=N—SN(CH3)2 und (CH3)2Si(Cl)—N=S=N—SN(CH3)2.In der letzten Verbindung kann man das Chloratom durch Diäthylamin substituieren. Die neuen Verbindungen stellen Zwischenprodukte für die Synthese cyclischer Schwefel-Stickstoff- Verbindungen dar. Sie wurden durch Massen-, IR-, 1H-NMR-Spektren und Elementaranalysen charakterisiert.
    Additional Material: 1 Tab.
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  • 8
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Biopolymers 14 (1975), S. 2373-2385 
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The kinetics of the acid hydrolysis of Streptococcus salivarius levan were studied by examining the weight-average molecular weight. The molecular weights were obtained in a continuous manner from light scattering. Two first order reactions were observed: an initial rapid reaction in competition with a slower reaction.Activation energies, activation entropies, as well as the rate dependence upon substrate and hydrogen ion concentrations were determined. The data seem to indicate that the fast reaction is related to the breaking of branch-point bonds while the slower reaction is related to the breaking of main-chain bonds. Thus, levan hydrolysis seems to be fundamentally different from the completely random degradation of other branched polysaccharides, i.e., dextran, glycogen, and amylopectin.
    Additional Material: 9 Ill.
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  • 9
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Biopolymers 16 (1977), S. 1319-1329 
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Circular dichroism spectra have been obtained for cationic poly(L-arginine) and poly(L-histidine) in aqueous solutions containing varying amounts of sodium dodecyl sulfate. The detergent induces a disorder-order transition in both polypeptides. In each case the transition is cooperative and occurs when the ratio of detergent to amino acid residue is near unity. The ordered structure formed by poly(L-arginine) is readily identifiable as an α helix. Poly(L-histidine) appears to form a β structure in which the 211-nm electronic absorption band of the imidazole group exhibits significant rotatory strength.
    Additional Material: 6 Ill.
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  • 10
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Biopolymers 14 (1975), S. 1283-1292 
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The molecular weights and radii of gyration of Streptococcus salivarius levan fractions were obtained from light-scattering measurements in water. Sedimentation coefficients and partial specific volumes of the fractions were also obtained. Double logarithmic plots of [η] versus M̄w and S0 versus M̄w yielded slopes having values of 0.17 and 0.62, respectively. The data and various calculated parameters show that levan from Streptococcus salivarius is highly branched and behaves hydrodynamically as a compact particle of spherical symmetry.
    Additional Material: 5 Ill.
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