Weight, derivative

The molecular weights calculated in this way agree very closely with the so-called chemical molecular weights, derived from chemical analysis, and the method therefore rivals the latter in accuracy, without the attendant complications attaching to chemical operations with pure substances. 

MSTFA Most volatile by-products of all. Particularly useful for the separation of low molecular weight derivatives in the presence of excess reagent. 

Baker, J., Andzelm, J., Scheiner, A., Delley, B., 1994, The Effect of Grid Quality and Weight Derivatives in Density Functional Calculations , J. Chem. Phys., 101, 8894. 

Johnson, B. G., Frisch, M. J., 1993, Analytic Second Derivatives of the Gradient-Corrected Density Functional Energy. Effect of Quadrature Weight Derivatives , Chem. Phys. Lett., 216, 133. 

Equations have been derived which relate G(scission) and G(crosslinking) to changes in Mn, Mw and Mz. Crosslinking produces branched molecules and the relative hydrodynamic volume (per mass unit) decreases compared with linear molecules. Therefore, molecular weights derived from viscometry and gel permeation chromatography will be subject to error. 

A product of this type will have over 50% of its weight derived from maleic anhydride. This very high content of reactive double bonds will lead to a very brittle solid when it is cross-linked with styrene. Without further modification, this solid material will have very high tensile moduli, probably over 600 kpsi, but a very low tensile elongation, way below 1 %. Such a brittle material obviously has only very limited applications. Thus, for most general-purpose applications, it is necessary to incorporate some chemically inert components to soften the polymer backbone. This will reduce the cross-linking density and improve the physical properties of the cured solid. 

M-step In this maximization step, the parameters /xr Xj, and pj are estimated. For fij and Xj weighted means and covariances are computed, with weights derived in the E-step, pj can be estimated by summing up all weights for group j and dividing by the sample size n. 

Marder, V. J., Shulman, N. R., and Carroll, W. R. (1969). High molecular weight derivatives of human fibrinogen produced by plasmin. J. Biol. Chem. 244, 2111-2119. 

In vitro studies have shown that dextran sulfate inhibits HIV binding, replication and syncytium formation, probably because they interfere with the ionic interaction between cell surface components such as CD4 or sulfated polysaccharides and positively charged amino acids concentrated in the V3 region of HIV gpl20 [ 127-129]. Again, low molecular weight derivatives with... 

While 3-H-3-phenyldiazirine was reported to be unstable on storage as a neat liquid (Smith and Knowles, 1975), its stability was improved in hexane solution at —20°C. Higher molecular weight derivatives of this compound have been stored for months in solution at —80°C without decomposition. 

Flocculants— The need to separate undesired. solid particles finely suspended in aqueous effluents, which is particularly relevant in wa.stewater treatment, the paper industry, etc.," - requires the use of water-soluble macromolecules, which arc mostly ionic in character and capable of interacting with the suspended material. With high-molecular-weight derivatives, the presence of a suitable content of ionogenic moieties as well as their uniform distribution along the polymeric chains are important in order to obtain the best performance of the flocculant, which should not completely cover the surface of the dispersed particles. 

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