Two gas phase deuterium/hydrogen exchange reactions are described utilizing a simple inexpensive glass catalyst tube containing 0.5% Pd on alumina through which gas mixtures can be passed and products collected for analysis. The first of these exchange reactions involves H 2 + D 2 , which proceeds at temperatures as low as 77 K yielding a mixture that includes HD. Products are analyzed by 1 H NMR spectrometry. At low temperatures, this reaction requires a catalyst, but it proceeds without a catalyst at high temperature of a gentle flame. The second deuterium/hydrogen exchange reaction involves CH 4 + D 2 producing a series of isotopologues, methane-d x , x = 0−4, with product analysis by GC−MS and 1 H NMR spectrometry. This reaction only takes place in the presence of a catalyst at elevated temperatures due to the large energy of activation of the sp 3 -carbon-to-hydrogen bond. Two outcomes have been observed in the literature regarding D/H exchange and methane. Some catalysts and temperature conditions yield a single-exchange result, methane-d 1 . Others yield multiple exchange results, such as we observe with our catalyst. The single exchange outcome is associated with lower temperatures. Two mechanisms, one by Kemball (1959) and one by Frennet (1974), have been put forth to explain single and multiple exchange outcomes. We discuss our results in the context of these mechanisms. Interested readers could develop a research experience for undergraduate chemistry students based on the openended experiments presented here.
This report provides a description of the current blood banking system and of the collection and derivation of quantitative information concerning system operation and blood cost.A reasonably accurate but somewhat incomplete profile of practices, attitudes, and likely costs of present and alternative systems has been developed. Among the topics presented are:(1) a discussion of the blood collection process including statistics on present use and future needs ; (2) information relating to donor motivation, attitudes and incentives; (3) a brief summary of demonstration programs in the U.S. and national blood programs in other countries which provides some insight concerning means for improving blood quality and availability;(4) a description of blood processing, storage and distribution procedures; (5) narrative and statistical information relating to blood utilization practices; (6) discussions of posttransfusion reactions and frozen blood programs; (7) a discussion of current governmental and professional standards, regulations and controls which influence many, but not all, concerns involved in blood collection and processing. This information serves as the basis for the selection of alternatives analyzed in a cost effectiveness analysis of eight apparently viable alternatives to the current system. Because of the possible variation which might be ascribed to many of the parameters used as a basis for costing alternatives, the sensitivity analysis is crucial in the comparison of alternatives.
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