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Various Reactions (various + reaction)
Terms modified by Various Reactions Selected AbstractsCopolymerization of D,L -lactide and glycolide in supercritical carbon dioxide with zinc octoate as catalystJOURNAL OF BIOMEDICAL MATERIALS RESEARCH, Issue 1 2008Rosario Mazarro Abstract The objective of the study is the development of a new technique based on supercritical technology for the production of bioabsorbable polymeric microparticles containing pharmaceutical principles, for their use in the controlled release of medicines. For this purpose, the ring-opening copolymerization of D,L -lactide and glycolide in supercritical carbon dioxide, using zinc(II) 2-ethylhexanoate (ZnOct2) as catalyst, was studied. The polymer obtained with ZnOct2 has similar characteristics to that obtained with stannous octoate (SnOct2), the conventional catalyst used up to now for this kind of polymerization process. Experiments were performed at various reaction times, pressures, and stirring rates. The most outstanding result was found by varying the stirring rate, where particles forming agglomerates seem to be obtained at the greater agitation levels. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2008 [source] Partitioning of metals (Cd, Co, Cu, Ni, Pb, Zn) in soils: concepts, methodologies, prediction and applications , a reviewEUROPEAN JOURNAL OF SOIL SCIENCE, Issue 4 2009F. Degryse Summary Prediction of the fate of metals in soil requires knowledge of their solid,liquid partitioning. This paper reviews analytical methods and models for measuring or predicting the solid,liquid partitioning of metals in aerobic soils, and collates experimental data. The partitioning is often expressed with an empirical distribution coefficient or Kd, which gives the ratio of the concentration in the solid phase to that in the solution phase. The Kd value of a metal reflects the net effect of various reactions in the solid and liquid phases and varies by orders of magnitude among soils. The Kd value can be derived from the solid,liquid distribution of added metal or that of the soil-borne metal. Only part of the solid-phase metal is rapidly exchangeable with the solution phase. Various methods have been developed to quantify this ,labile' phase, and Kd values based on this phase often correlate better with soil properties than Kd values based on total concentration, and are more appropriate to express metal ion buffering in solute transport models. The in situ soil solution is the preferred solution phase for Kd determinations. Alternatively, water or dilute-salt extracts can be used, but these may underestimate in situ concentrations of dissolved metals because of dilution of metal-complexing ligands such as dissolved organic matter. Multi-surface models and empirical models have been proposed to predict metal partitioning from soil properties. Though soil pH is the most important soil property determining the retention of the free metal ion, Kd values based on total dissolved metal in solution may show little pH dependence for metal ions that have strong affinity for dissolved organic matter. The Kd coefficient is used as an equilibrium constant in risk assessment models. However, slow dissociation of metal complexes in solution and slow exchange of metals between labile and non-labile pools in the solid phase may invalidate this equilibrium assumption. [source] Stress and the skinINTERNATIONAL JOURNAL OF COSMETIC SCIENCE, Issue 4 2006J. Hosoi Synopsis ,The skin is the mirror which reflects the state of the mind.',The skin is the window of the mind.' These have been proverbs since ancient times. It is the topic of this article. Our life became convenient with the information technology these days but too much information often drives us on. We suffer from mental stress rather than physical stress. Since Selye advocated stress reaction, various reactions in the body have been described. Skin is also a target organ of the stress reaction. What the effects of stress are and how stress affects the skin are summarized in this review. Possible use of fragrance for the regulation of the stress reaction is also introduced. Résumé «La peau est le miroir qui reflète l'état de l'esprit»«La peau est une fenêtre sur l'esprit». Ces proverbes sont anciens. Ils sont le thème de cet article. Aujourd'hui, la technologie de l'information rend notre vie commode, mais trop d'informations souvent nous surmènent. Nous souffrons de stress mental plutôt que de stress physique. Depuis la réaction au stress découverte par Selye, de nombreuses réactions du corps ont été décrites. La peau est également un organe cible de la réaction au stress. Cette revue récapitule les effets du stress et comment ce dernier agit sur la peau. L'utilisation potentielle de parfums pour réguler la réaction au stress est également abordée. [source] Transglutaminase Catalyzed Reactions: Impact on Food ApplicationsJOURNAL OF FOOD SCIENCE, Issue 8 2002G.A.H. DeJong ABSTRACT: Transglutaminases can perform various reactions that are based on cross-linking, acyl-transfer and deamidation. These enzymes are found in many different organisms where they have very specific roles. The basic reaction mechanism of these transglutaminases is similar. The reactions catalyzed by transglutaminases have proven to be useful in production of different kinds of protein ingredients and food products. In this review, we will show important aspects of transglutaminase cross-linking in respect to substrate specificity, accessibility of proteins, regulation and differences in reactions and safety. These aspects will be viewed in respect to food applications [source] Occupational exposure of Brazilian neonatal intensive care workers to latex antigensALLERGY, Issue 1 2004R. A. M. Lopes Background:, Frequent exposure to latex causes various reactions such as respiratory symptoms and anaphylactic shock. In these cases, proteins found in natural latex are responsible for the serious systemic antilatex-mediated immediate hypersensitive reactions. Methods:, Cross-sectional descriptive survey focusing on 96 Brazilian health care workers (HCW) in the neonatal intensive care unit at CAISM, State University of Campinas UNICAMP, Brazil. All subjects were interviewed, donated blood samples for the latex-specific immunoglobulin E measurement and underwent the skin prick test (SPT) with an antigen extracted from latex gloves. Results:, The prevalence of latex positive SPT was 8%. There were eight SPT positive and only one serologic test was in agreement with the SPT. Overall, there was evidence of an association between the latex SPT and reported eczema (P = 0.01); food allergy (P = 0.009) with pineapple (P = 0.01). Conclusions:, These results suggest that the identification of reactions of immediate hypersensitivity mediated by antilatex antibodies in HCW should be encouraged to prevent occupational exposure to latex products. [source] Backbone dynamics of SDF-1, determined by NMR: Interpretation in the presence of monomer,dimer equilibriumPROTEIN SCIENCE, Issue 11 2006Olga K. Baryshnikova Abstract SDF-1, is a member of the chemokine family implicated in various reactions in the immune system. The interaction of SDF-1, with its receptor, CXCR4, is responsible for metastasis of a variety of cancers. SDF-1, is also known to play a role in HIV-1 pathogenesis. The structures of SDF-1, determined by NMR spectroscopy have been shown to be monomeric while X-ray structures are dimeric. Biochemical data and in vivo studies suggest that dimerization is likely to be important for the function of chemokines. We report here the dynamics of SDF-1, determined through measurement of main chain 15N NMR relaxation data. The data were obtained at several concentrations of SDF-1, and used to determine a dimerization constant of ,5 mM for a monomer,dimer equilibrium. The dimerization constant was subsequently used to extrapolate values for the relaxation data corresponding to monomeric SDF-1,. The experimental relaxation data and the extrapolated data for monomeric SDF-1, were analyzed using the model free approach. The model free analysis indicated that SDF-1, is rigid on the nano- to picosecond timescale with flexible termini. Several residues involved in the dimer interface display slow micro- to millisecond timescale motions attributable to chemical exchange such as monomer,dimer equilibrium. NMR relaxation measurements are shown to be applicable for studying oligomerization processes such as the dimerization of SDF-1,. [source] | |||||||||||||