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  • Chemistry  (3)
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  • 1
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biospectroscopy 1 (1995), S. 133-140 
    ISSN: 1075-4261
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Physics
    Notes: Fourier transform infrared (FTIR) spectroscopy was used to directly monitor peroxidative damage to membrane phospholipid acyl chains in erythrocyte membranes. Samples were suspended in a mixed 2H2O/H2O buffer system, thereby producing a “spectral window” in the C-H stretching region of the infrared spectrum. A decrease in the number of acyl chain C=C bonds upon erythrocyte peroxidation was quantitated directly from the spectra of isolated membranes. Second-derivative spectroscopy permitted the conformationally sensitive membrane acyl chain methylene stretching modes to be separated from the protein (mostly hemoglobin) vibrations that dominate the spectra of intact cells. The sensitivity of these modes in erythrocytes was then determined in a series of thermotropic experiments. The effect of peroxidation upon the membrane acyl chain conformational order was monitored in isolated membranes and intact cells. No change in conformational order was detected upon peroxidation in intact cell and ghost spectra. In contrast, experiments with pure unsaturated phospholipids demonstrated that decreasing the C=C bond population results in increased conformational order. The finding of identical results for peroxidation versus control samples in isolated membranes (“ghosts”) validates the results observed for intact cells. FTIR technology permits the direct monitoring of conformational order in the acyl chains of intact cells. © 1995 John Wiley & Sons, Inc.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Process Safety Progress 16 (1997), S. 83-85 
    ISSN: 1066-8527
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: OSHA regulations for Process Safety Management (PSM) [1] and EPA regulations addressing risk management programs (RMP) for chemical accidental release prevention [2] require industry to identify and analyze potential process hazards. This effort, known as the Process Hazard Analysis (PHA) element of the PSM and RMP standards, involves the use of qualitative hazard identification or analysis techniques acceptable to OSHA or EPA.While making these assessments, two issue arise; how to judge acceptable risk and how to decide on appropriate risk reduction measures where necessary. Neither regulation defines a model for making risk management decisions. In the absence of formal, sanctioned risk management criteria, it is recommended that companies adopt a standard, defensible ranking scheme to provide a common basis for decision-making. This should be based on the company's defined safety goals. This article discusses an approach, common to many companies, that qualitatively ranks the risk of identified scenarios. In addition, this article examines the possible problems of using various ranking schemes and risk criteria.
    Additional Material: 1 Ill.
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  • 3
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: The purpose of this study was to determine the effect of air-borne gaseous impurities, introduced during trituration, on the strength of amalgams.Four experiments were conducted. Each experiment consisted of a control group (1) in which the amalgam was triturated in air and an experimental group (2) in which the amalgam was triturated in argon, an inert gas. Standard specimens yielded mean diametral tensile strengths of 5950 psi (1) and 6603 psi (2). Hand compacted specimens yielded mean diametral tensile strengths of 5829 psi (1) and 6412 psi (2). Standard specimens yielded mean compressive strengths of 46,636 psi (1) and 47,269 psi (2). Specimens compacted hydraulically yielded mean uniaxial tensile strengths of 10,928 psi (1) and 11,660 psi (2).Statistically, the differences between the means for each experiment are significant. Hence, trituration in an inert gas has been shown to be an effective method for increasing the strength of amalgam.
    Additional Material: 4 Tab.
    Type of Medium: Electronic Resource
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