Branched-chain history

Elevated concentrations of the n-Cl3 to -CIH alkanes and branched-chain and cyclic analogs were measured in a building having a history of air quality complaints the source was found to be volatilization from hydraulic fluids used in the building elevators (Weschler et al., 1990). 

Maple Syrup Urine Disease Figure 18-28 shows the pathway for the degradation of branched-chain amino acids and the site of the biochemical defect that causes maple syrup urine disease. The initial findings that eventually led to the discovery of the defect in this disease were presented in three papers published in the late 1950s and early 1960s. This problem traces the history of the findings from initial clinical observations to proposal of a biochemical mechanism. 

Other important factors include monomer sequence distribution, distribution of graft and crosslink sites along the chains, the occurrence of branching per se, and the general phenomena of side reactions. In addition, stirring rate, the detailed post-reaction "workup procedure, the temperature history, subsequent processing and fabrication conditions, etc. must be considered since these have major effects on the nature of the product. 

During the long history of FT synthesis, various approaches have been developed to control product selectivity. Parameters like temperature, pressure, H. CO ratio, conversion, space velocity and alkalization of iron catalysts influence chain length, chain branching, (he ole fin/paraffin ratio and the alcohol selectivity as well as carbon deposition and methane selectivity. The effect of the different parameters can be obtained from Table IV 9]. As a typical example for the... 

Microscopic Characteristics Conidia one celled, typically globose, brownish colored and often sculptured. Conidiophores are also darkly pigmented, simple, undeveloped and similar to the mycelium or at times having short lateral branches at whose swollen apices a single conidium is borne. Alternately, short chains of microconidia formed by flask shaped cells (phiatides) can occur. History, Use and/or Medical Implications Selected for use in compost nutrient conversion during Phase II of composting. 

During the mid-1930s, free radical ethylene pol)mierization was developed by ICI. At temperatures above 150°C and pressures exceeding 1000 atm, radical initiators produce radicals which initiate free radical ethylene polymerization. Due to inter- and intramolecular chain transfer reaction via H atom transfer with the free radical at the polymer chain end, high pressure polyethylene contains short- and long-chain branches which reduce polyethylene (PE) crystallinity and consequently also PE density. Therefore this class of polyolefins became known as low density polyethylene (LDPE). The history of polyolefins was compiled by Seymour and Cheng [1]. 

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