Physico-chemical modification

Novel utilities for presently available products are a more productive area. (Who would not be interested if the fiber from grains could be used functionally in the snack food industry for reasons other than as a filler.) But these types of utility demand extreme physico-chemical modifications involving prolonged research and much expenditure. 

Physico-chemical modifications of the solution Influence on the spectroscopic parameters 471... 

The presence of water during the treatments compared to the Blank run in dodecane alone induceds some modifications. The catalytic activity decreases to one third in the first hours of treatment independently of the presence of hydrogen sulfide while the hydrogenation - hydiogenolysis selectivity is not modified. This deactivation should be attributed to a physico-chemical modification of the catalyst samples. 

Edible fats and/or oils, or mixtures of these, whose origin is vegetable or rendered animal carcass fats or any form of oil from a marine species that has been affirmed as GRAS or listed as a food additive for this use, any or all of which may have been subjected to an accepted process of physico-chemical modification. They may contain small amounts of other lipids such as phosphatides, or unsaponifiable constituents and of free fatty acids naturally present in the fat or oil. 

Solid icy surfaces are observed both in the interstellar medium as mantles on silicatic or carbonaceous grains and on many objects in the Solar System." In space, these icy targets are continuously bombarded by energetic ions from solar wind and flares, planetary magnetospheres, stellar winds and galactic cosmic rays. When an energetic ion collides with an icy target produces physico-chemical modifications in the latter. The study of those effects is based on laboratory ion irradiation experiments carried out under physical conditions as close as possible to the astrophysical ones. 

The versatile properties and manufacturability of polymers has evoked immense interest in developing a class of biomaterials with the potential to interface with biological systems [1]. However, polymers are prone to pathogenic attack resulting in deterioration of properties, malfunction and so on. Various methods such as the ionic binding technique, incorporation of metal particles/metal oxides/nanoparticles (NP) and physico-chemical modification via, e.g., the addition of quaternary ammonium salts and blending with antimicrobial polymers, have been explored for the fabrication of bactericidal materials [2], However, these methods can result in reduced biocompatibility, cytotoxicity and eco-toxicity. 

The results of this analysis can be arolied in the study of real systems in two ways. As mentioned in the Introduction, it may Ik used as a tool to predict weather impedance spectroscopy is senalive enough to monitor a specific phenomenon (e.j.diffusion) in a complex system. Also, one can use these results to chedc the consistency of experimental data with hypotheses concerning the physico-chemical modification of systems, as follows ... 

The inserts prepared from polymer solutions had DSC traces very similar to those of the corresponding parent homopolymers, as far as both temperature and enthalpy changes are concerned. This implies that no DSC-appreciable physico-chemical modifications occur during the preparation of the films. 

Details are given of the effects of strong ionising radiations on the physico-chemical modifications of epoxy resins. The sensitivity of the epoxy resins to radiation was determined using carbon 13 NMR. 20 refs. 

Knowledge of the mechanism of action and investigations on the physico-chemical characteristics of the therapeutically used dalbaheptides has stimulated the transformation of natural antibiotics into new derivatives using both chemical and biosynthetic modification. 

Stmctural and chemical modification of urethane containing polymer matri-ces with macrocycles - calixarenes having reactive hydrazide groups have been carried out and stmcture, physico chemical and sensor properties of polyure-thanesemicarbazides (PUS) synthesised have been studied. The polymers obtained (on the base of polypropylene glycol MM 1000 and polysiloxane diol MM 860, hexamethylene diisocyanate and calixarene dihydrazide) are identified by IR-spectroscopy, size exclusion chromatography (SEC), DSC, WAXS and SAXS methods. 

The synthesis of new polymeric materials having complex properties has recently become of great practical importance to polymer chemistry and technology. The synthesis of new materials can be prepared by either their monomers or modification of used polymers in industry. Today, polystyrene (PS), which is widely used in industrial applications as polyolefins and polyvinylchlorides, is also used for the production of plastic materials, which are used instead of metals in technology. For this reason, it is important to synthesize different PS plastic materials. Among the modification of PS, two methods can be considered, viz. physical and chemical modifications. These methods are extensively used to increase physico-mechanical properties, such as resistance to strike, air, or temperature for the synthesizing of new PS plastic materials. 

New elastic polymeric materials (resistance to higher stroke or air) can be obtained by using physical modification methods, but using this method, two phases (PS and rubber) in the mixture were formed. Small rubber particles spread as a PS layer and, after awhile, the relationship between the layers decreases and rubber particles gather in the upper layer of the materials. This can be the cause of the loss of resistance of the materials. These material disadvantages have stimulated the polymer synthesis to increase the PS resistance to higher physico-mechanical properties, such as higher temperature and stroke for the chemical modification of PS with various functional modifiers. 

Compared to the chemical modification reactions of PS, alkylation and acylation reactions are preferred to other reactions, such as halogenation, nitrolation, sulfo-nation, amination, and chloromethylation, etc. because the obtained polyfunctional PS has higher physico-me-chanical properties. 

The chemical modification of PS with epichlorohydrin (EC), maleic anhydride (MA), acetic anhydride (AA), butadiene, and isoprene in the presence of cationic catalysis such as AICI3, FeCU, BF3 0(C2H5)2, ZnCb, TiCL, and SnCU, have been extensively studied under various conditions for the last 15 years. We have also studied their kinetics, physico-mechanical, thermal, and dielec-... 

New insights into the analysis of hydrophobically post-translational modified proteins could be achieved by the construction of lipidated proteins in a combination of bioorganic synthesis of activated lipopeptides and bacterial expression of the protein backbone (Fig. 19). The physico-chemical properties of such artificial lipoproteins differ substantially from those of the corresponding lipopeptides. The pronounced dominance of the hydrophilic protein moiety (e.g., for the Ras protein 181 amino acids) over a short lipopeptide with one or two hydrophobic modifications provides solubility up to 10 4 mol/1, while the biotinylated or fluorescence labeled lipopeptides exhibit low solubility in aqueous solutions and can be applied in the biophysical experiments only in vesicle integrated form or dissolved in organic solvent. 

The optical properties of semiconductor QDs (Fig. la-c, Tables 1 and 2) are controlled by the particle size, size distribution (dispersity), constituent material, shape, and surface chemistry. Accordingly, their physico-chemical properties depend to a considerable degree on particle synthesis and surface modification. Typical diameters of QDs range between 1 and 6 nm. The most prominent optical features of QDs are an absorption that gradually increases toward shorter... 

The influence of chain length and side-chain modifications of ACTH-derived peptides on active avoidance behaviour in rats will be discussed. H-Met(02)-Glu-His--Phe-D-Lys-Phe-OH (Org 2766) emerged from these studies as an orally active peptide with an increased potency and selectivity of action. Physico-chemical data (from the literature) on the reference peptide ACTH--(4-10) did not point to a preferred conformation in solution, whereas in the crystalline state an antiparallel 3-pleated sheet structure was found. At the receptor site we suggested an a-helical conformation in which the Phe and Met residues are close together. Additional support for this suggestion came from the behavioural activity of [des-Tyr", Met ]enkephalin and of cyclo--(-Phe-Met-cAhx-), eAhx merely serving as a spacer. 

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