Macromolecular nature

The polymer in natural rubber consists almost entirely of ci -poly(isoprene) (1.6). The molecules are linear, with relative molar mass typically lying between 300 000 and 500 000. The macromolecular nature of rubber was established mainly by Staudinger in 1922, when he hydrogenated the material and obtained a product that retained its colloidal character, rather than yielding fragments of low relative molar mass. 

The views of Staudinger, on the one hand, and Meyer and Mark, on the other, actually were not so far apart as the tenor of their polemics might indicate. Their agreement on the essential macromolecular nature of high polymers appears to have contributed materially to the rejection of the simple cyclic formulas widely accepted up to that time. 

GC requires low molecular weight molecules, and the macromolecular nature of proteinaceous materials (made up of 21 amino acids covalently condensed) means that they are typically too large to be readily identifiable and time consuming pretreatments of the sample are required. In order to free the amino acids, hydrolysis is required. Subsequent steps of purification to eliminate pigment interferences are also often necessary. Consequently sample pretreatments must be carefully carried out to reduce the risk of loss and/or contamination of the sample. 

The UV radiation adsorbed by chromophoric DOM stimulates production of free radical (singlet) O2. This leads to high concentrations of the free radicals within and around the CDOM, creating local conditions of high reactivity. Thus, chromophoric DOM, which tends to be HMW, can be thought of as a photochemical micro reactor in which free radical oxidations are promoted. Given its macromolecular nature, CDOM... 

Peppas, N.A. Lucht, M.L. "Investigations of the Crosslinked Macromolecular Nature of Bituminous Coals," Final Report, DOE Contract No. DE-F622-78E, 12279, 1980. 

The effects mentioned in the last sub-section are all local ones and do not depend upon the macromolecular nature of the material. A more important group of properties comprises those that are affected by the changes that LCB produces in the space-filling behaviour of polymer molecules under conditions in which they are free or relatively free from conformational constraints, that is in solution or in the melt, or in the amorphous state below 7. ... 

Peculiarities of Thermotropic Liquid-Crystalline Polymers Related to Their Macromolecular Nature... 

The macromolecular nature provides an interesting feature of LC polymeric cholesterics, namely the possibility of obtaining monochromic films. Thus for polymeric liquid crystals the helix pitch is practically not altered with temperature below Tg, when a cholesteric phase is frozen in a glassy matrix (Fig. 23a). This implies that fast cooling of polymeric films from a mesomorphic state (shown with arrows) fixes their optical properties, which makes it possible to use them at ordinary temperatures as selective monochromic reflectors. On the other hand, such polymeric films display the extraordinary polarizing properties of cholesterics, i.e. the different absorption... 

However, even the complete understanding of these areas will not suffice to reap the full benefits embedded in the macromolecular nature of polymeric materials, which are inherent in the naturally occurring and synthetic polymeric building blocks. For that, a priori quantitative prediction of product properties, made of yet nonexistent chains or combinations of chains of different monomeric building blocks from basic principles, requiring information of only the macromolecular structure and processing conditions, is needed. 

Because of their extensive use in industrial activities, phenolic compounds are abundant in many wastewaters. They are present in oil refining, petrochemical, plastic, pesticide, carbon liquefaction, and food processing industrial wastewaters. In addition, phenol-like structures are part of the macromolecular natural humic substances present in water humics are known precursors of trihalomethane compounds in drinking water chlorination [176,177], These compounds are refractory to conventional processes such as biological oxidation because of their toxicity for microorganisms [178]. 

The macromolecular nature and structural heterogeneity of the polymeric SOs allow the existence of several different binding sites this holds in particular for proteins which are quite heterogeneous by nature. As a consequence they have usually a broad spectrum of applicability, but their or-values are rather mtxlerate and are typically between 1 and 3. In addition, it is difficult to study the mechanism of chiral recognition and to identify the site of chiral recognition. The exact arrangement of the SA in the active chiral recognition site remains still widely unknown. 

Another marked disadvantage should be mentioned. As a consequence of the macromolecular nature of the selector, its molar loading on the support material is quite low. Since the number of binding sites per protein molecule is also limited (in contrast to polysaccharide and other polymeric CSPs consisting of the same repetitive sub-selector units), these CSPs have a low loadability [203]. This greatly restricts their use for preparative enantioseparations. 

Interfacial chemistry and system hydrodynamics control the aggregation, deposition, and separation of particles and particle-reactive substances in natural aquatic environments and in many technological systems. Hydrodynamics (particle transport) are particularly sensitive to particle size and size distribution colloidal stability is usually determined by the presence of macromolecular natural organic substances. Recent theoretical and experimental studies of the effects of these two classes of variables on solid-liquid separation in aquatic systems are presented and discussed. 

The focus here is on the effects of dissolved natural organic matter (NOM) on the colloidal stability of particles in aquatic systems and, in particular, on the importance of the macromolecular nature of NOM in these effects. The approach used here has three components (1) modeling studies with mathematical polyelectrolytes, surfaces, and solvents (2) laboratory studies with well-characterized polyelectrolytes and particles and (3) laboratory studies with aquatic NOM, also using well-characterized particles. 

Humin is the insoluble fraction of sedimentary humic substances. Little is known of its chemical composition and of its individuality as a class of humic substances, primarily because its macromolecular nature and complexity have precluded detailed analyses by conventional methods used for organic structural analyses. The advent of solid-state NMR has allowed... 

H saturated humic, fulvic and hydrophilic macromolecular natural organic matter was isolated from the river Dodder, Ireland, by adsorption and cation exchange chromatography (Hayes, personal communication). 

Soluble macromolecular (natural and synthetic) systems are frequently used as lysosomotropic agents. Because of their ability to extravasate, they have been extensively... 

Solubility measurements indicated that the peracids were of macromolecular nature, being formed by the oxidation of macroaldehydes, presumably via radical attack on methyl hydrogens, subsequent peroxidation and disproportionation (Zahradnikova et al, 1991). The difficulty of analysis of these reactive species has meant that unequivocal quantitation of the reactions has not been achieved. 

Product information is presented for Amina T 100, a newly developed polymer from Creavis GmbH with antimicrobial action. Its crucial advantages lies in its macromolecular nature. In contrast to other polymers provided conventionally with biocides, there is no wash-out of low molecular toxic components. The starting materials are not antimicrobially active, and the antimicrobial action develops only in the polymer. Product properties are listed, its spectrum of activity is identified, and kinetics of reduction are charted. 

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