Schmid’s factor

On application of a tensile load, the yield stress, (Tq varies widely in ceramics, but considering Eq. (4.6) in terms of yield, the yield stress value is minimal when (f> — X — 45°, giving a value of 0.5 for the product of the cosines (Schmid s factor). In this case, the maximum value attained for t is 0.5ffo- Beyond 0.5, (Tq increases again. 

Schmid s observation of the dependence of the reaction rate on the square of the concentration of nitrous acid was interpreted by Hammett (1940, p. 294) as due to the rate-limiting formation of dinitrogen trioxide, N203. The consequent attack of the amine by N203 was postulated to be faster therefore the concentration of the amine has no influence on the overall rate (zero order with respect to amine). Similarly, Hammett regards the second factor of Schmid s equation for diazotization in the presence of hydrochloric or hydrobromic acid as the result of the formation of nitrosyl halide. 

Equation (4.6) gives the resolved shear stress . The product in the equation is known as the Schmid factor and determines whether the orientation is favorable for shp. The conditions for slip are given by Schmid s Law and the value of Eq. (4.6), often represented in the literature by Tj, indicating the onset of plastic deformation and called critical resolved shear stress . CRSS is a structure-sensitive property, since it is very dependent on impurities and the way the crystal was grown and handled. 

The discoveries of Csp s and trigger factor may represent the tip of a large iceberg. In view of the pervasive effects of low temperature on the structures of all classes of macromolecules, it is reasonable to conjecture that many more types of proteins will be discovered whose roles are to offset the effects of cold shock on the cell. Some of these molecules may be expressed constitutively and may be part of the normal machinery of the cell. For example, certain ribosomal proteins are thought to function as RNA chaperones, and if present in sufficient amounts, these proteins may allow the cell to cope with the effects of cold shock on the structures of certain classes of RNAs. In yeast, a constitutively expressed ribosomal protein has helicase activity, and mutation in the gene encoding the protein confers on the cells a cold-sensitive phenotype (Schmid and Linder, 1992). Perhaps the apparent absence of cold-induced RNA chaperones in eukaryotic cells is... 

Hundreds of impressive examples of enantioselective lipase-catalysed reactions are known, including industrial processes as in the case of the BASF method of chiral amine production (Collins et al. 1997 Breuer et al. 2004 Schmid and Verger 1998). However, the classical problem of substrate acceptance or lack of enantioselectivity (or both) persists. We were able to meet this challenge in model studies regarding the hydrolytic kinetic resolution of the ester rac-1 with formation of carboxylic acid 2, catalysed by the lipase from Pseudomonas aeruginosa. The wild-type (WT) lipase is only slightly (S )-selective, the selectivity factor amounting to a mere E = 1.1 (Scheme 1). 

Askling J, Fahrbach K, Nordstrom B, Ross S, Schmid CH, and Symmons D. 2011. Cancer risk with tumor necrosis factor alpha (TNF) inhibitors meta-analysis of randomized controlled trials of adalimumab, etanercept, and infliximab using patient level data. Pharmacoepidemiology and Drug Safety 20 119-130. 

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