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Acid Polymer (acid + polymer)
Selected AbstractsUse of induction promoters to regulate hyaluronan synthase and UDP-glucose-6-dehydrogenase of Streptococcus zooepidemicus expression in Lactococcus lactis: a case study of the regulation mechanism of hyaluronic acid polymerJOURNAL OF APPLIED MICROBIOLOGY, Issue 1 2009J.Z. Sheng Abstract Aims:, To determine the effects of the ratios of hyaluronan synthase expression level to precursor sugar UDP-GlcA biosynthesis ability on the molecular weight (MW) of hyaluronic acid (HA) in recombinant Lactococcus lactis. Methods and Results:, The genes szHasA (hyaluronan synthase gene) and szHasB (UDP-glucose-6-dehydrogenase gene) of Streptococcus zooepidemicus were introduced into L. lactis under the control of nisA promoter and lacA promoter respectively, resulting in a dual-plasmid controlled expression system. The effects of the ratios of hyaluronan synthase expression level to the precursor sugar UDP-GlcA biosynthesis ability under different induction concentration collocations with nisin and lactose on the MW of HA in recombinant L. lactis were determined. The results showed that the final weight-average molecular weight () of HA correlated with the relative ratios of HasA (hyaluronan synthase) expression level to the concentration of UDP-GlcA. Conclusions:, Regulating the relative ratios of HasA expression level to the precursor sugar biosynthesis ability was an efficient method to control the size of HA. Significance and Impact of the Study:, This study put forward a guide to establish an efficacious way to control the size of HA in fermentation. [source] Polymerization of N -isopropylacrylamide in the presence of poly(acrylic acid) and poly(methacrylic acid) containing ,-unsaturated end-groupsJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 18 2007Ronan Mchale Poly(N -Isopropylacrylamide, NIPAM) propagating radicals add to acrylic acid (AA) macromonomer and methacrylic acid polymer containing unsaturated ,-end-group to respectively give novel graft copolymer (represented as , (AA) and , (NIPAM) units) and addition fragmentation chain transfer (AFCT). [Color figure can be viewed in the online issue, which is available at www.interscience.wiley. com.] [source] Aryl acrylate based high-internal-phase emulsions as precursors for reactive monolithic polymer supportsJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 2 2005Peter Krajnc Abstract Water-in-oil high-internal-phase emulsions (HIPEs), containing 4-nitrophenyl acrylate and 2,4,6-trichlorophenyl acrylate as reactive monomers, were prepared and polymerized, and highly porous monolithic materials resulted. The novel materials were studied by combustion analysis, Fourier transform infrared spectroscopy scanning electron microscopy, mercury porosimetry, and N2 adsorption/desorption analysis. With both esters, cellular macroporous monolithic polymers were obtained; the use of 4-nitrophenyl acrylate resulted in a cellular material with void diameters between 3 and 7 ,m and approximately 3-,m interconnects, whereas the use of 2,4,6-trichlorophenyl acrylate yielded a foam with void diameters between 2 and 5 ,m, most interconnects being around 1 ,m. The resulting monoliths proved to be very reactive toward nucleophiles, and possibilities of functionalizing the novel polymer supports were demonstrated via reactions with amines bearing additional functional groups and via the synthesis of an acid chloride derivative. Tris(hydroxymethyl)aminomethane and tris(2-aminoethyl)amine derivatives were obtained. The hydrolysis of 4-nitrophenylacrylate removed the nitrophenyl group, yielding a monolithic acrylic acid polymer. Furthermore, functionalization to immobilized acid chloride was performed very efficiently, with more than 95% of the acid groups reacting. The measurement of the nitrogen content in 4-nitrophenyl acrylate poly(HIPE)s after various times of hydrolysis showed the influence of the total pore volume of the monolithic polymers on the velocity of the reaction, which was faster with the more porous polymer. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 296,303, 2005 [source] Glass bead grafting with poly(carboxylic acid) polymers and maleic anhydride copolymersPOLYMERS FOR ADVANCED TECHNOLOGIES, Issue 2 2008H. Zengin Abstract Glass beads were etched with acids and bases to increase the surface porosity and the number of silanol groups that could be used for grafting materials to the surfaces. The pretreated glass beads were functionalized using 3-aminopropyltriethoxysilane (APS) coupling agent and then further chemically modified by reacting the carboxyl groups of carboxylic acid polymers with the amino groups of the pregrafted APS. Several carboxylic acid polymers and poly(maleic anhydride) copolymers, such as poly(acrylic acid) (PAA), poly(methacrylic acid) (PMA), poly(styrene-alt-maleic anhydride) (PSMA), and poly(ethylene-alt-maleic anhydride) (PEMA) were grafted onto the bead surface. The chemical modifications were investigated and characterized by FT-IR spectroscopy, particle size analysis, and tensiometry for contact angle and porosity changes. The amount of APS and the different polymer grafted on the surface was determined from thermal gravimetric analysis and elemental analysis data. Spectroscopic studies and elemental analysis data showed that carboxylic acid polymers and maleic anhydride copolymers were chemically attached to the glass bead surface. The improved surface properties of surface modified glass beads were determined by measuring water and hexane penetration rates and contact angle. Contact angles increased and porosity decreased as the molecular weights of the polymer increased. The contact angles increased with the hydrophobicity of the attached polymer. The surface morphology was examined by scanning electron microscopy (SEM) and showed an increase in roughness for etched glass beads. Copyright © 2007 John Wiley & Sons, Ltd. [source] Promoted random orientation of the phenyl substituent of phenylhydroquinone,terephthalic acid polyesters prepared with a diphenyl chlorophosphate/pyridine condensing agentJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 10 2001Fukuji Higashi Abstract The reaction of sterically hindered hydroxyl groups at the 2-position of methylhydroquinone and phenylhydroquinone (PhHQ) to form esters was largely promoted by their slow addition to benzoic acid activated by diphenyl chlorophosphate in pyridine. A modification of this reaction was applied to the preparation of thermotropic terephthalic acid/PhHQ and 2,5-dichloroterephthalic acid/PhHQ polymers with randomly oriented phenyl substituents, and the properties of the polymers were studied in terms of their transition temperatures, which were determined by differential scanning calorimetry and microscopic observation. The melting points were lowered by about 30,50 °C by the dropwise addition of PhHQ over 10,30 min. The molecular structures of the 2,5-dichloroterephthalic acid/PhHQ polymers were studied by 13C NMR. © 2001 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 39: 1726,1732, 2001 [source] | ||||||||||