Covalent immobilization of glucose oxidase onto new modified acrylonitrile copolymer/silica gel hybrid supports

New polymer/silica gel hybrid supports were prepared by coating high surface area of silica gel with modified acrylonitrile copolymer. The concentrations of the modifying agent (NaOH) and the modified polymer were varied. GOD was covalently immobilized on these hybrid supports and the relative activity and the amount of bound protein were determined. The highest relative activity and sufficient amount of bound protein of the immobilized GOD were achieved in 10% NaOH and 2% solution of modified acrylonitrile copolymer. The influence of glutaraldehyde concentration and the storage time on enzyme efficiency were examined. Glutaraldehyde concentration of 0.5% is optimal for the immobilized GOD. It was shown that the covalently bound enzyme (using 0.5% glutaraldehyde) had higher relative activity than the activity of the adsorbed enzyme. Covalently immobilized GOD with 0.5% glutaraldehyde was more stable for four months in comparison with the one immobilized on pure silica gel, hybrid support with 10% glutaraldehyde and the free enzyme. The effect of the pore size on the enzyme efficiency was studied on four types of silica gel with different pore size. Silica with large pores (CPC-Silica carrier, 375 A) presented higher relative activity than those with smaller pore size (Silica gel with 4, 40 and 100 A). The amount of bound protein was also reduced with decreasing the pore size. The effect of particle size was studied and it was found out that the smaller the particle size was, the greater the activity and the amount of immobilized enzyme were. The obtained results proved that these new polymer/silica gel hybrid supports were suitable for GOD immobilization.     

Barrier property of clay/Acrylonitrile‐butadiene copolymer nanocomposite

The resistance to air permeation was investigated for ­an intercalated clay/acrylonitrile‐butadiene copolymer ­nanocomposite. The nanocomposite is prepared by melt mixing the organo‐treated montmorillonite into a rubber matrix, together with peroxide curative, and crosslinked by conventional compression molding for typical rubbers. In the case of intercalated nanocomposite, the air permeability decreases considerably with increasing clay content, and the decreasing trend agrees reasonably with the Neilson's tortuous model. No considerable improvement is found when the pure montmorillonite is added. Copyright © 2002 John Wiley & Sons, Ltd.     

Syntheses Based on Natural α-Amino Acids. Cyanoethylation of 3-Substituted 5-Methyl-2-thiohydantoins

Starting from α-alanine, the C- and S-cyanoethyl derivatives of 5-methyl-3-phenyl(allyl)-2-thiohydantoins have been synthesized. It was shown that the products of hydrolysis of C-cyanoethyl derivatives, 5-methyl-3-phenyl(allyl)-(β-carboxyethyl)-2-thiohydantoins, are formed in addition. __________ Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 11, pp. 1657–1661, November, 2005.     

相转移催化合成β-酞酰亚胺基丙腈

用固-液相转移催化法，以酞酰亚胺和丙烯腈为原料，无水K2CO3为催化剂，经Michael反应合成了β-酞酰亚胺基丙腈，并研究了不同条件下的反应结果。实验表明，利用Michael反应在温和条件下可获得较高产率的产物，克服了以往用季铵碱作催化剂或用DMF作溶剂的缺点。     

Modification on liquid retention property of cassava starch by radiation grafting with acrylonitrile. I. Effect of γ-irradiation on grafting parameters

Radiation modification on liquid retention properties of native cassava starch, gelatinized at 85°C, by graft copolymerization with acrylonitrile was carried out by mutual irradiation to gamma-rays. A thin aluminum foil was used to cover the inner wall of the reaction vessel, so that the homopolymer concentration was reduced to be less than 1.0% with a distilled water retention value of 665 g/g of the dry weight of the saponified grafted product. Confirmation of graft copolymerization and saponification reactions was made by the infrared spectrophotometric technique. The combined effect of radiation parameters in terms of an irradiation time and a dose rate to the total dose on the extent of the grafting reaction expressed in terms of grafting parameters which directly influenced liquid retention values was evaluated in conjunction with statistical analysis.     

Preparation and performance analysis of PE-supported P(AN-co-MMA) gel polymer electrolyte for lithium ion battery application

Copolymer, poly(acrylonitrile-co-methyl methacrylate) (P(AN-co-MMA)), was synthesized by solution polymerization with different mole ratios of monomers, acrylonitrile (AN) and methyl methacrylate (MMA). Polyethylene (PE) supported copolymer and gel polymer electrolyte (GPE) were prepared with this copolymer and their performances were characterized with FTIR, TGA, SEM, and electrochemical methods. It is found that the GPE using the PE-supported copolymer with AN to MMA = 4:1 (mole) exhibits an ionic conductivity of 2.06 × 10⁻³ S cm⁻¹ at room temperature. The copolymer is stable up to 270 °C. The PE-supported copolymer shows a cross-linked porous structure and has 150 wt% of electrolyte uptake. The GPE is compatible with anode and cathode of lithium ion battery at high voltage and its electrochemical window is 5.5 V (vs. Li/Li⁺). With the application of the PE-supported GPE in lithium ion battery, the battery shows its good rate and initial discharge capacity and cyclic stability.     

Preparation of antimicrobial sutures by preirradiation grafting onto polypropylene monofilament

Antimicrobial sutures were prepared by the radiation grafting of acrylonitrile monomer onto polypropylene (PP) monofilament. The grafted sutures were subsequently hydrolyzed to transform nitrile groups into carboxylic groups for the immobilization of antimicrobial drug, tetracycline hydrochloride (TC). The modified sutures show continuous release of drug for a period of 4–5 days. The antimicrobial activity of the sutures was determined against both Gram positive and Gram negative bacteria by the zone of inhibition technique. Zone of inhibition was observed around the drug‐containing sutures in the plate inoculated with Escherichia coli (E. coli), Klebsiella pneumonea (K. pneumonea), and Staphylococcus aureus (S. aureus). The results of infection studies in albino rats against S. aureus showed no infection even after fourth postoperative day of surgery. This is because of the release of the TC drug at the site of injury, which inhibits the bacterial growth. Copyright © 2008 John Wiley & Sons, Ltd.     

两相体系中催化氢化丙烯腈制备丙腈

膦配体TPPTS(三-间磺酸钠-三苯基膦)的水溶性很好,有关其过渡金属配合物催化剂的应用与研究活跃。近年来,对丙烯腈C=C双键加氢的研究多集中在以钯为中心金属的多相催化体系上,已报道的有聚硅氧烷钯体系,膦酸锆负载钯体系,高分子负载钯．金属氧化物催化剂,SiO2负     

铈对低负载Pd/Al2O3催化剂加氢丙烯腈的改性效应

钯基催化剂对烯烃及烯烃类衍生物有很好的加氢活性。但钯催化剂价格昂贵,单一的钯容易中毒失活,研究表明：掺入稀土氧化物能够提高钯催化剂在载体上的分散度,增大其氧化及氢化活性,提高催化剂的寿命及稳定性。但稀土助剂对双键选择性加氢影响的研究却很少有报     

Fe/MgO催化剂上乙腈和甲醇选择性合成丙烯腈

丙烯腈(AN)是一种重要的有机合成单体,自从1960年美国Sohio公司开发出以丙烯、氨和空气为原料的丙烯氨氧化生产丙烯腈的SOHIO工艺以来,目前全球95％以上的丙烯腈是通过SOHIO路线生产的。而乙腈(ACN)是丙烯氨氧化制丙烯腈的主要副产物,每吨丙烯腈副产25～