铝热剂SHS合成模拟核废物固化产物的组成结构分析

以Fe2O3为氧化剂,采用铝热剂(Al与Fe2O3的质量比为1:3)自蔓延高温合成(self-propagating high temperature synthesis,SHS)技术制备模拟核废物砂土固化产物,研究了不同模拟示踪核素在固化产物中的存在状态。通过扫描电镜、显气孔率测试、密度分析、X射线衍射分析等分析了固化产物的表面形貌和组成结构。结果表明:采用SHS技术固化砂土,固化产物为无定形玻璃和晶体颗粒构成的混合物,密度为2.60～3.05g/cm3,其中晶体成分主要是α-Al2O3,约占晶体质量的49.4%～63.6%,其他为示踪核素Ce,Sr,Ba,Er与SiO2结合生成的Ce2SiO5,BaSrSi2O6和Er2SiO5,各约占晶体质量的12.0%～18.7%。     

Q相对脱硫石膏氯离子固化和抗压强度的影响

受限于高氯离子迁移性能,大量品质较低的脱硫石膏在石膏制品中无法被有效利用。本文研究了Q相(Ca₂₀Al₂₆Mg₃Si₃O₆₈)对脱硫石膏中氯离子迁移性能的影响规律与机理。结果表明,在脱硫石膏中以10%~30%(质量分数)的比例掺入Q相,其水化产物主要为二水硫酸钙、钙矾石和AH₃凝胶,脱硫石膏样品中氯离子固化率和绝干抗压强度均得到了较大提升。掺入30%的Q相对脱硫石膏性能提升效果最佳,此时氯离子固化率达19.55%,石膏的绝干抗压强度提升了约51.5%。结合XRD、SEM和综合热分析探明了Q相-脱硫石膏水化产物中钙矾石、AH₃凝胶对氯离子固化和石膏力学性能改善的作用机理。     

分子伴侣与蛋白质复性的简介

综述了分子伴侣的结构、性质、作用机理及分子伴侣在蛋白质复性过程中的应用.     

载酶塑料填料的制备与优化

酶催化反应精馏（ERD）是使用酶作催化剂,将反应精馏（RD）与生物催化相结合的过程。近年来,该工艺过程因其高选择性和环境友好性而日益得到认可。本文研究了塑料填料固定化酶,将含有脂肪酶的溶胶-凝胶溶液喷涂到塑料填料表面,制备了载酶塑料填料。载酶填料作为精馏柱内不可或缺的结构单元,其稳定性是影响ERD发展的重要因素。溶胶-凝胶配方各组分的相对含量直接影响凝胶基质和被包埋酶的性能,因此,本研究对凝胶配方进行了优化,以改善塑料填料载酶涂层的开裂问题。用傅里叶红外光谱（FTIR）、扫描电镜（SEM）对样品进行了表征,并对黏附强度、循环稳定性、机械性能、酶活性和催化效率进行了研究。结果表明,塑料填料表面凝胶涂层的脆性开裂情况得到了改善,涂层与填料的结合强度提高了14.2%。溶胶-凝胶配方的优化可以改善凝胶基质的性能,提高载酶填料的机械稳定性,且优化配方制备的催化剂具有优异的酶学稳定性。这一工作证明了塑料填料固定化酶的可行性,为ERD的工业化打下基础。     

纳米结构酶催化剂研究进展

将酶负载于载体上可以提高工业应用中酶的稳定性并便于重复使用。纳米材料的发展为固定化酶提供了新的契机,利用纳米材料固定化酶有望进一步提高酶在工业环境中的催化性能、拓展固定化酶的应用范围。本文主要关注近年来在纳米结构酶催化剂方面的研究进展,重点介绍本研究组以无机晶体、金属有机骨架材料、石墨烯和功能高分子等为载体进行酶固定化以及酶催化过程多尺度分子模拟方法的研究进展,讨论了纳米结构酶催化剂的发展前景。     

The synthesis of new chiral salen complexes immobilized on MCM‐41 by grafting and their catalytic activity in the asymmetric borohydride reduction of ketones

The new chiral salen complexes were synthesized and supported on mesoporous MCM‐41 through the condensation of 3‐aminopropyltrimethoxysilane and 2,6‐diformyl‐4‐tert‐butylphenol by the multi‐grafting method. The immobilized optically active Co(II) salen complexes showed a very high enantioselectivity in the asymmetric borohydride reduction of aromatic ketones. The chiral salen Co(II) complexes immobilized over MCM‐41 were stable during the reaction and exhibited a relatively high enantioselectivity for the reduction of ketones as compared with the homogeneous salen catalysts. This revised version was published online in July 2006 with corrections to the Cover Date.     

Borago officinalis oil: Fatty acid fractionation by immobilized Candida rugosa lipase

γ-Linolenic acid (Z,Z,Z-6,9,12-octadecatrienoic acid), a very important polyunsaturated fatty acid is found in the free fatty acid fraction prepared by the hydrolysis of borage oil. Our aim was to enrich this fraction in γ-linolenic acid using selective esterification. Candida rugosa lipase was used as catalyst after immobilization on the following ion-exchange resins: Amberlite IRC50, IRA35, IRA93, and Duolite A7, A368, A568. In every case, immobilization modified the lipae’s specificity: palmitic, stearic, oleic, and linoleic acids were preferentially esterified compared to γ-linolenic acid, thus allowing a γ-linolenic acid enrichment of 3.0.     

Immobilization of lipase on poly(N-vinyl-2-pyrrolidone-co-2-hydroxyethyl methacrylate) hydrogel for the synthesis of butyl oleate

Lipase from Candida rugosa was immobilized by entrapment on poly(N-vinyl-2-pyrrolidone-co-2-hydroxyethyl methacrylate) [poly(VP-co-HEMA)] hydrogel, cross-linked with ethylene glycol dimethacrylate (EDMA). The immobilized enzyme was used in the esterification of oleic acid with butanol in hexane. The activities of the immobilized enzyme preparations and the leaching of the enzyme from the hydrogel supports with respect to composition were investigated. The thermal, solvent, and storage stability of the immobilized preparations also were determined. Increasing the percentage VP from 0 to 90, which corresponds to the increase in the hydrophilicity of the hydrogels, increased the activity of the immobilized enzyme. Lipase immobilized onto VP(%):HEMA(%), 90:10 hydrogel had the highest activity. Increasing the hydrophobicity of the hydrogel (increasing the percentage HEMA) seemed to decrease leaching of the enzyme from the support. Immobilized lipase on 100% HEMA hydrogel indicated highest entrapment and lowest leaching by hexane washing. The lipase immobilized on VP(%):HEMA(%), 50:50 hydrogel showed highest thermal, solvent, and storage stability compared to lipase immobilized on other hydrogel compositions as well as the native lipase.     

京尼平交联制备枯草杆菌碱性蛋白酶聚集体

本研究利用新型交联剂京尼平制备了枯草杆菌碱性蛋白酶交联聚集体(BAP-CLEAs)。以酶活回收率为指标,确定了BAP-CLEAs制备的最佳条件为:交联剂质量浓度0.50%,交联温度35℃,交联时间12 h,此时BAP-CLEAs的酶活回收率为55.04%。采用扫描电镜及红外光谱对BAP-CLEAs进行表征,结果证明枯草杆菌碱性蛋白酶在京尼平的作用下成功交联。与游离酶相比,BAP-CLEAs的最适p H值向碱性方向偏移,由9.4变为10.3,在较宽的p H范围和温度范围内保持较高的酶活。另外,在2%浓度的酪蛋白底物中重复使用5次后,BAP-CLEAs还能保持86.42%的酶活性。以上催化特性的结果表明,枯草杆菌碱性蛋白酶在京尼平的作用下可成功交联形成酶聚集体,且该交联酶聚集体具有比游离酶更优越的p H稳定性、温度稳定性和重复使用稳定性,有良好的工业应用前景。     

固定化活性干酵母发酵生产苹果酒工艺及澄清技术研究

以苹果为原料,研究了海藻酸钙固定活性干酵母制备干型苹果酒的发酵及下胶澄清工艺技术.结果表明:苹果破碎时用0.1%柠檬酸和0.1%异VC进行护色,并添加0.02%果胶酶和0.05%纤维素酶处理20min,接种0.5%固定化活性干酵母在20～25℃下发酵至高泡期,经糖分调整至潜在酒精度10,再进行二次发酵,苹果原酒中添加0.2g/L明胶、0.2g/L皂土和0.1g/L壳聚糖澄清30min,可得金黄透亮、香气优雅、口感纯净的干型苹果酒.