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  • Chemistry  (5)
  • 1985-1989  (5)
  • 1970-1974
  • 1925-1929
  • 1989  (1)
  • 1985  (4)
  • 1
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 23 (1989), S. 253-266 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: We report the biocompatibility in the rat brain of a controlled-release, biodegradable polymer, the polyanhydride poly-[bis(p-carboxyphenoxy)propane-sebacic acid] copolymer (PCPP-SA) in a 20:80 formulation. The biodegradable polyanhydride can be used for drug delivery directly into the brain, circumventing the difficulties posed by the blood - brain barrier and avoiding the consequences of having to administer toxic doses systemically to reach therapeutic doses in the central nervous system. The tissue reaction in the presence of PCPP-SA was compared to that seen with other standard neurosurgical implants. Fifty-six adult Sprague-Dawley rats were assigned to one of seven groups and underwent bilateral frontal lobe implantation of PCPP-SA (42 hemispheres), Surgicel (oxidized regenerated cellulose) (35 hemispheres), or Gelfoam (absorbable gelatin sponge) (35 hemispheres). None of the animals showed any behavioral changes or neurological deficits suggestive of either systemic or localized toxicity from the biodegradable polyanhydride, all surviving to the scheduled data of sacrifice. PCPP-SA evoked a well localized inflammatory reaction, comparable to that of Surgicel, which resolved as the PCPP-SA polymer degraded over five weeks. The biodegradable polyanhydride has been shown in this study to be nontoxic and biocompatible in the rat brain, when compared to standard neurosurgical implants.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 17 (1985), S. 345-354 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Calculations are performed to model several phenomena observed when a photosensitive oscillating chemical reaction, the Briggs-Rauscher (BR) reaction, is subject to irradiation in a continuous-flow stirred-tank reactor. The BR mechanism proposed earlier by De Kepper and Epstein is supplemented by additional steps involving the photogeneration and subsequent reaction of iodine atoms. The calculations show qualitative agreement with the following experimentally observed phenomena: (a) change in the period and amplitude of oscillation as a function of the intensity of constant illumination, (b) synchronization between periodically varying illumination and the period of chemical oscillation, (c) phase shifts induced by single light pulses, and (d) dark steady states which are excitable by single light pulses and become oscillatory at appropriate levels of constant illumination.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Plant/Operations Progress 4 (1985), S. 200-206 
    ISSN: 0278-4513
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The reaction between chlorite ion and thiourea has been studied both in a closed (batch) system and in a flow reactor (CSTR). The principal stoichiometry is given by \documentclass{article}\pagestyle{empty}\begin{document}$$ 2{\rm ClO}_{\rm 2} ^{\rm - } + {\rm CS(NH}_{\rm 2} {\rm)}_{\rm 2} + {\rm 2NH}_{\rm 4} ^ + + {\rm CO}_{\rm 2} + 2{\rm Cl}^{\rm - } + {\rm SO}_{\rm 4} ^{{\rm 2 - }} $$\end{document} In batch, the reaction displays an induction period, whose length is proportional to [CS(NH2)2]/[ClO2-] [H+], followed by the rapid buildup and disappearance of a ClO2 intermediate. At [ClO2-]/[CS(NH2)2] ratios between 2.5 and 3.5, a second peak in the ClO2 absorbance is observed. In the CSTR, this iodine-free system displays simple and complex periodic oscillation, bistability, aperiodic oscillation, and birhythmicity.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 17 (1985), S. 601-612 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The reaction between nitric acid and thiocyanate has been studied both in batch and flow configurations. The batch reaction is autocatalytic with an induction period which is decreased by the addition of HNO2. At the nitric acid concentrations employed (1-10 M), a red NOSCNH+ intermediate is formed. The reaction in a flow reactor exhibits bistability. A model involving competitive reactions of SCN- and NOSCNH+ with NO2 is suggested, and computer simulations with this model give good agreement with both the batch and flow experiments.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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