High molecular weight factors

Burd G, OP Ward (1996) Involvement of a surface-active high molecular weight factor in degradation of polycyclic aromatic hydrocarbons by Pseudomonas marginalis. Can J Microbiol 42 791-797. 

Solution Polymerization. Plant scale polymerizations ia water are conducted either adiabaticaHy or isotherm ally. Molecular weight control, exotherm control, and reduction of residual monomer are factors which limit the types of initiators employed. Commercially available high molecular weight solution polyacrylamides are usually manufactured and sold at about 5% soHds so that the viscosities permit the final product to be pumped easily. 

Equatioa-of-state theories employ characteristic volume, temperature, and pressure parameters that must be derived from volumetric data for the pure components. Owiag to the availabiHty of commercial iastmments for such measurements, there is a growing data source for use ia these theories (9,11,20). Like the simpler Flory-Huggias theory, these theories coataia an iateraction parameter that is the principal factor ia determining phase behavior ia bleads of high molecular weight polymers. 

High molecular weight primary, secondary, and tertiary amines can be employed as extractants for zirconium and hafnium in hydrochloric acid (49—51). With similar aqueous-phase conditions, the selectivity is in the order tertiary > secondary > primary amines. The addition of small amounts of nitric acid increases the separation of zirconium and hafnium but decreases the zirconium yield. Good extraction of zirconium and hafnium from ca 1 Af sulfuric acid has been effected with tertiary amines (52—54), with separation factors of 10 or more. A system of this type, using trioctylarnine in kerosene as the organic solvent, is used by Nippon Mining of Japan in the production of zirconium (55). 

Factor XI. Factor XI is a Hver-synthesized glycoprotein that circulates in a zymogen form as a dimer. It is converted to its active serine protease form by Factor Xlla in the presence of high molecular weight kininogen. Calcium is not required for this activation step. 

Figure 9.1. Schemalic illuslralion of dependence of Ihe modulus of a polymer on a variety of factors. A is an amorphous polymer of moderate molecular weight whereas B is of such a high molecular weight that entanglements inhibit flow. Similar effects are shown in C and D, where the polymer is respectively lightly and highly cross-linked. In E and F the polymer is capable of crystallisation, F being more highly crystalline than E...

Analytical information taken from a chromatogram has almost exclusively involved either retention data (retention times, capacity factors, etc.) for peak identification or peak heights and peak areas for quantitative assessment. The width of the peak has been rarely used for analytical purposes, except occasionally to obtain approximate values for peak areas. Nevertheless, as seen from the Rate Theory, the peak width is inversely proportional to the solute diffusivity which, in turn, is a function of the solute molecular weight. It follows that for high molecular weight materials, particularly those that cannot be volatalized in the ionization source of a mass spectrometer, peak width measurement offers an approximate source of molecular weight data for very intractable solutes. 

Ra and Rb in Table 17.8 are less than 1.7 because the molecular weights of the standards differ by a factor less than 10. They will be used later to compare the separation efficiency in the high molecular weight range and low molecular weight range for these four linear columns. 

Factor Xlla is a serine protease that activates FXI to FXIa (Fig. 5). This system is not of physiologic relevance since patients with hereditary deficiencies of factor XII, prekallikrein, and high-molecular weight kininogen do not present with bleeding symptoms. 

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