半纤维素酶研究进展及在纤维素乙醇领域的应用

近年来,在纤维素乙醇研究及示范进程中,纤维素酶的研究取得了较大的进展,半纤维素酶的研究却关注较少.半纤维素酶作为一个复杂的酶系,在木质纤维素底物水解过程发挥了关键作用.基于玉米秸秆的半纤维素结构,概述了玉米秸秆降解所需半纤维素酶系的酶学特性和协同作用等方面的研究进展,探讨了纤维素乙醇预处理工艺与酶制剂复配之间的关系,并展望了半纤维素酶未来的研究方向.     

固态发酵中纤维素基质降解过程初步研究

利用斜卧青霉(Penicillium decumbens JUA10)对汽爆麦草和淀粉质的混合基质进行固态发酵，通过分析各种成份及酶活力变化，研究了各成份的降解速率，并探讨了纤维素、半纤维素降解与纤维素酶、半纤维素酶酶活力的关系. 纤维素基质固态发酵中木质纤维素的降解过程实际是同步糖化发酵过程，还原糖不会积累形成对纤维素酶、半纤维素酶的反馈抑制；纤维素降解与纤维素酶的酶活性、半纤维素的降解与半纤维素的酶活性不成正比. 木质纤维素的降解难主要是木质纤维素结构造成的. 半纤维素的降解甚至比纤维素降解更慢，淀粉容易降解，木质素几乎不降解.     

纤维素酶的研究进展

综述了纤维素酶的发展近况及研究进展,介绍了纤维素酶水解结晶纤维素的机制、反应的协同作用及碳水化合物结合组件在反应中所起的作用,并对纤维素酶的研究趋势进行了展望。     

影响纤维素酶解的因素和纤维素酶被吸附性能的研究

本文以预处理的木质纤维素的结晶纤维素为材料,研究纤维素的吸附过程及影响酶 主要是而探讨纤维素酶解机制。     

纤维素降解辅助蛋白及其作用机理研究进展

化石燃料的日渐枯竭及环境污染的日益严重使得生物质原料的资源化、能源化利用受到广泛关注。木质纤维素是地球上最丰富的可再生生物质,其通过生物转化可获得多种燃料和化学品,而纤维素难以有效糖化是木质纤维素生物转化的主要瓶颈。本文介绍了某些纤维素非降解性辅助蛋白提高纤维素酶解效率的相关研究进展,重点分析了近些年发现并研究较多的裂解性多糖单加氧酶（AA9和CBM33）、纤维二糖脱氢酶（CDH）、扩展蛋白（expansin）、膨胀素（SWOI）等几种纤维素辅助蛋白及其协助纤维素降解的机理,总结出这些辅助蛋白主要是通过促进木质素或半纤维素降解以及破坏纤维素的氢键网络和结构来协同纤维素酶催化纤维素的糖化降解。通过以上概括和评述,认为这些辅助蛋白虽然一定程度上可以促进纤维素的酶解,但其研究和应用还仅限于实验室基础研究,如何将其有效并廉价应用于木质纤维素生物转化的工业过程还面临着巨大挑战。指出相关研究工作的重点还需要从廉价而有效的蛋白筛选与构建、协同作用机理解析、过程优化与强化等方面深入开展。     

纤维素酶的研究进展

综述了纤维素酶的发展近况及研究进展,介绍了纤维素酶水解结晶纤维素的机制、反应的协同作用及碳水化合物结合组件在反应中所起的作用,并对纤维素酶的研究趋势进行了展望。     

木质纤维素新型预处理与顽抗特性

木质纤维素是地球上最丰富的可再生生物质资源,其中纤维类多糖的酶催化降解是木质纤维素生物精炼的关键环节之一。对木质纤维素进行预处理,破坏底物的顽抗特性,是实现木质纤维素高效酶解糖化的必要途径。为此,各国学者围绕预处理技术开发以及底物顽抗特性开展了大量研究,本文对近几年来在这两方面取得的最新成果进行了综述和分析。在预处理方面,重点介绍了组合预处理、低温预处理、绿色溶剂与电化学预处理4类新型预处理技术,并对预处理效果与技术优势进行了评价;在底物顽抗特性方面,综述了木质素、结晶度、酶可及度等不同顽抗特性对纤维素酶解的影响规律,重点总结了近年来顽抗特性研究方面的新方法、新认识与新理解。上述研究成果有助于了解当前木质纤维素预处理研究的导向以及明确制约纤维素酶解的关键因素,为设计和筛选适宜的预处理方式、深刻理解纤维素酶解机制提供基础和指导。     

周期刺激固态发酵生产纤维素酶

木质纤维素是世界上最丰富的可再生性资源,而开发利用木质纤维素的关键就是纤维素酶。固态发酵法生产纤维素酶产量高、成本低,优于液态发酵法,但因为固态发酵反应器比较独特,因此未能迅速普及。生化工程国家重点实验室研制了新型周期刺激固态反应器进行规模化生产,产品质量符合市场的要求。     

提高麦草可酶解性的常压甘油自催化预处理

针对小分子有机溶剂预处理时存在的缺陷,尝试高沸点甘油预处理木质纤维素以提高其可酶解性的研究。通过对预处理时一些关键参数进行初步优化,获得适宜预处理条件为:质量分数70%甘油溶液、液固比(麦草与甘油水溶液的质量比)20、蒸煮温度230℃和保温1 h;麦草纤维素保留率约92%,木质素脱除率达74%;常压甘油自催化预处理麦草在纤维素酶5FPU/g干底物时4,8 h纤维素酶解转化率为41.3%。结合电镜观察和红外光谱分析,初步认为常压甘油自催化预处理通过脱除木质纤维素原料中不利于纤维素酶解的组分及打破其致密不均一结构,从而提高了木质纤维素的可酶解性。     

植物/微生物源活性蛋白协同纤维素酶水解木质纤维素的研究进展

综述了微生物源活性蛋白(水解酶和酶促因子)和植物源活性蛋白(水解酶和酶促因子)分别应用于木质纤维素-糖平台的研究进展,总结了植物/微生物源活性蛋白协同纤维素酶水解木质纤维素的作用机制,并对由植物/微生物源活性蛋白组合构建经济高效的纤维素酶水解体系进行了展望。     

与强者同场竞技 靠创新促进发展——访青岛福润德塑料挤出技术有限公司总经理赵炳仁先生

一年一届的中国国际塑料橡胶工业展览会(国际橡塑展),是全球多个行业寻找橡塑工业世界性商贸伙伴的机遇,也是企业开拓中国以至亚洲市场商机之"金钥匙"。在25届国     

Hydrogels reinforced with nanoclays with improved response rate

Two series of semiinterpenetrating networks (SIPN) based on linear hydrophilic poly(vinyl alcohol) (PVA) and thermo‐responsive poly(N‐isopropylacrylamide) (PNIPA), physically crosslinked with inorganic clay, are presented. The hydrogels with different crosslinking densities were prepared by varying the content of clay from 1 to 6 wt % and contained linear interpenetrant, PVA in the range of 0.5–1.5 wt %. The effect of clay content on swelling/deswelling behavior and phase transition in PNIPA gels, as well as the feasibility of reinforcing the gels with high molecular weight PVA, were analyzed. The thermal response of hydrogels, followed by DSC, confirmed that the insertion of hydrophilic PVA did not have a significant effect on the onset of the volume phase transition temperature, while the response was faster. The equilibrium degree of swelling of SIPNs and PNIPA hydrogels was in the range of 9–79 and decreased with increasing content of clay. The internal morphology and surface wettability of the hydrogels were investigated by scanning electron microscope analysis and contact angle measurements, respectively. The network structural parameters of the PNIPA and SIPN nanocomposites hydrogels, such as the average molecular weight between crosslinks, M_c, and effective crosslinking density, N_e, were determined by dynamic mechanical analysis. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44535.     

Biological studies with cyclopropenoids inactivated with fatty acids

Cyclopropenoids inactivated by reactingSterculia foetida oil with cottonseed oil fatty acids were fed at three dietary levels to growing rats and laying hens for 4 weeks. At the termination of the experiments, all animals were autopsied and examined microscopically for pathological lesions, but no pathology that could be related to dietary treatment was observed. Hemoglobin, packed cell volume and plasma cholesterol were similar in animals fed all of the diets. Growth rate of rats and egg production of hens fed the experimental diets were similar to those of animals fed the control diet. After 3 and 6 months of storage, eggs from hens fed the inactivated cyclopropenoids were normal and showed no evidence of the unusual characteristics of cyclopropenoid feeding. Lipids of heart, liver and adipose tissues of all the rats and hens varied little from the normal fatty acid composition. Small amounts of three unidentified fatty acids were found in the adipose tissues of rats fed the higher levels of inactivated cyclopropenoids. The results of these feeding studies suggest that inactivation of cyclopropenoids with fatty acids eliminates the unusual biological effects attributable to cyclopropenoids. Presented at the AOCS Meeting, New Orleans, April 1970.     

Electrodialysis with brine solutions oversaturated with calcium sulfate

Electrodialysis (ED) was applied to concentrate brine solutions of various concentrations — similar to effluentsfrom the desalination of brackish and industrial water — to about 20%. The consequent reduction in effluent volumes would facilitate a reduction in disposal costs. The energy requirement for concentrating solutions from 70 to 300 mN (0.4-1.8%) to 3.9 N (20%) was in the range 1.5-7.1 kWh/m³, in contrast to approximately 25 kWh/m³ by thermal evaporation. With the aim of preventing precipitation of CaSO4 on the membranes, laboratory-scale ED experiments were carried out on solutions of different compositions to determine the conditions that would lead to the precipitation of excess gypsum on gypsum seeds in a separate precipitator. The results were then applied in a pilot-scale ED unit in which the brine that circulated through the ED brine cells passed through a separate CaSO, precipitator containing gypsum seeds.     

高压电动机受潮现场处理的技术分析

山东铝业公司水泥厂（以下简称我厂）运行的大型高压电动机较多．有时由于长时间停运或者环境的潮湿，导致电动机的绝缘水平下降，致使电动机不能再次正常启动。因大型电动机是企业的关键设备，其运行好坏直接影响企业生产的正常与否，进而影响企业效益。     

Boundary-Layer Structure with Hydrogen Combustion with Different Injection Intensities

Results of numerical simulation of the influence of intensity of hydrogen injection through a porous surface in the case of hydrogen burning in the boundary layer are presented. Turbulent characteristics of the flow were simulated using the k–epsiv; turbulence model with Chien's modification for low Reynolds numbers. The diffusion model (infinitely large burning rate) was used to describe the chemical reaction process, but the difference in diffusion coefficients of different substances was taken into account. A comparison of injection with and without combustion shows that the presence of a heat-release front delays the laminar–turbulent transition and significantly deforms the profiles of density and viscosity of the gas mixture. As the injection velocity increases, the flame front is shifted from the porous surface toward the outer edge of the boundary layer. The contributions of injection itself and combustion to reduction of skin friction are analyzed. Key wrds: boundary layer, combustion, porous injection, heat and mass transfer, friction.     

Crosslinking of styrene-butadiene rubber with polyurethanes bicapped with benzyocyclobutene

Summary A polyurethane prepared from 1,9-nonanediol and toluene-2,4-diisocyanate with M_n=11,840, was capped on both ends in a reaction with 4-(benzocyclobutenyl) methanol. The polyurethane was used to crosslink styrene-butadiene rubber through Diels-Alder reactions on the benzocyclobutene functionality. The synthesis and characterization of 4-(benzocyclobutenyl) methanol, a molecule not reported previously, is presented. The crosslinking reaction was carried out on intimate mixtures of the telechelic polyurethane and SBR at elevated temperature and pressure. Various physical properties of the crosslinked material were studied.Work done at the Department of Chemistry, University of Akron, Akron, OH 44325, USA     

OMC法煤气脱硫装置的操作经验

讨论了在ＯＭＣ法煤气脱硫工艺中,贫液碱度、贫液中盐类含量、脱硫剂ＯＭＣ浓度和ＯＭＣ质量等因素对煤气脱硫效率的影响,指出了提高脱硫效率的途径和降低消耗的经验。     

Crosslinking with malonate blocked isocyanates and with melamine resins

Automotive clearcoats with improved acid etch resistance are being formulated using a combination of a dialkyl malonate blocked polyisocyanate, a melamine crosslinker, and an acrylic polyol,^1,2 These coatings contain lower levels of melamine crosslinker compared to conventional acrylic/HMMM systems and show excellent acid etch resistance. We explored the reaction mechanism of this complex crosslinking system and found explanations for the good chemical resistance properties. Presented at the 25th International Waterborne, High-Solids, and Powder Coatings Symposium, February 18–20, 1998, New Orleans, LA. Science Rd., Norwalk, CT 06852; E-mail: AlexHe@Kingindustries.com and Wblank@Kingindustries.com.     

宝塔山:诚信赢天下,创新求发展——解读陕西宝塔山油漆股份有限公司

位于西部大开发的龙头省份——陕西省的陕西宝塔山油漆股份有限公司,自1958年创建以来,历经40多年的积累,40多年的发展,现已成为西北地区产销量最大的涂料生产企业和中国涂料工业骨干企业,以非凡的努力奠定了西北涂料业旗舰的地位。其资本结构的调整、诚信经营的建设及创新发展的模式,对涂料行业的发展可带来一些启迪借鉴。