多酚氧化酶催化单宁的氧化聚合反应研究

研究了多酚氧化酶催化单宁的氧化聚合反应情况，探索了反应条件及7种化合物对酶活性的抑制效果，，对产物进行了红外光谱和紫外光谱测试，相对粘度法测定了产物的分子量，结果表明，，反应的最佳条件是PH为5．29，温度为30℃，在所用抑制剂中，硫酸铜的抑制作用最强，与单宁酸的IR图相比，产物的－OH吸收带变窄，在1260cm^-1处吸收峰增强，而紫外吸收无变化，产物平均分子量为3541，说明多酚氧化酶能催化单宁的氧化聚合。     

固定化多酚氧化酶催化合成邻苯二酚

利用壳聚糖固定化蘑菇多酚氧化酶催化氧化苯酚合成邻苯二酚,考察了固定化多酚氧化酶羟基化反应条件对目的产物产率的影响.确定适宜的羟基化工艺条件为:以氯仿为溶剂、底物浓度为20 mmol·L-1,pH值为7.0,含水量为0.9%、温度为30℃、反应时间为5 h,在此条件下催化合成邻苯二酚的产率为11.02%.     

专利快递

Z0 40 78　固定化多酚氧化酶催化高纯度茶多酚生产高纯度茶黄素的方法　公开号:CN 1 40 35 80A ,公开日:2 0 0 3.3.1 9　本发明包括将多酚氧化酶用包埋材料进行固定化,固定化的多酚氧化酶在一定的反应条件下,使高纯度的茶多酚氧化聚合生成高纯度的茶黄素,然后将茶黄素溶液用溶剂萃取,浓缩干燥,得到茶黄素含量75 %以上的高纯度茶黄素产品。本发明工艺步骤简单,设备投入少,既可以降低生产成本,由于多酚氧化酶得到固定化,因此酶促反应又可以连续化,可根据需要控制茶多酚的氧化程度和产品质量,尤其避免使用多种酸和碱等化学试验,是一种保护环…     

多酚氧化酶-硅藻土耦合系统选择性氧化/吸附邻苯二酚

研究了多酚氧化酶-硅藻土耦合系统在苯甲醚共存条件下氧化邻苯二酚及产物吸附过程的特性.多酚氧化酶表现出对酚类物质的特异性催化作用,不受共存非酚类物质的影响;硅藻土与反应产物之间的特异性吸附作用有利于从溶液中分离邻苯二酚.耦合系统对酶促反应具有增强效应,多酚氧化酶在溶液中的相应半衰期增加2.4倍;当硅藻土/酶的质量比为6时,最大分离效率达到98.76 %.     

固定化香蕉多酚氧化酶催化降解水中的2,4-二氯苯酚

用聚马来松香酰乙二胺-Cu(Ⅱ)固定化香蕉多酚氧化酶催化降解废水中的2,4-二氯苯酚(DCP),探讨了影响反应的几种因素.结果表明,固定化香蕉多酚氧化酶催化降解反应的最佳pH为6.0,最佳降解温度为40℃;该固定化酶连续降解2,4-二氯苯酚6次后仍能保持19％的降解率.     

聚马来松香酰乙二胺-Cu（Ⅱ）配合物的合成及在固定化酶中的应用

介绍了聚马来松香酰乙二胺-Cu(Ⅱ)高分子配合物的制备和固定化香蕉多酚氧化酶的方法,测定了固定化香蕉多酚氧化酶的活性和米氏常数,研究了温度和pH值对固定化香蕉多酚氧化酶催化活性的影响及固定化香蕉多酚氧化酶的重复催化活性。结果表明,聚马来松香酰乙二胺-Cu(Ⅱ)高分子配合物,是香蕉多酚氧化酶的良好固定化载体,固定化香蕉多酚氧化酶的米氏常数Km=4.56×10-3mol.L-1,小于天然香蕉多酚氧化酶的米氏常数(1.95×10-2mol.L-1),固定化香蕉多酚氧化酶的耐热性和耐酸碱性均优于天然香蕉多酚氧化酶,并有一定的重复使用性。对香蕉多酚氧化酶的固定化方式和固定化香蕉多酚氧化酶的催化反应机理也进行了初步探讨。     

聚马来松香酰乙二胺-Cu(Ⅱ)配合物的合成及

介绍了聚马来松香酰乙二胺-Cu(Ⅱ)高分子配合物的制备和固定化香蕉多酚氧化酶的方法,测定了固定化香蕉多酚氧化酶的活性和米氏常数,研究了温度和pH值对固定化香蕉多酚氧化酶催化活性的影响及固定化香蕉多酚氧化酶的重复催化活性.结果表明,聚马来松香酰乙二胺-Cu(Ⅱ)高分子配合物,是香蕉多酚氧化酶的良好固定化载体,固定化香蕉多酚氧化酶的米氏常数Km=4.56×10-3 mol·L-1,小于天然香蕉多酚氧化酶的米氏常数(1.95×10-2mol·L-1),固定化香蕉多酚氧化酶的耐热性和耐酸碱性均优于天然香蕉多酚氧化酶,并有一定的重复使用性.对香蕉多酚氧化酶的固定化方式和固定化香蕉多酚氧化酶的催化反应机理也进行了初步探讨.     

茂金属/有机硼化物催化体系催化1-癸烯聚合

采用茂金属催化体系Ph_2C(Cp-9-Flu)ZrCl_2/C_6H_5NH(CH_3)_2B(C_6F_5)_4/Al(~iBu)_3催化1-癸烯聚合,考察了催化剂浓度、Al和Zr以及有机硼化物和Zr物质的量之比、反应温度和反应时间等工艺条件对产物的影响,并采用核磁共振对其产物与1-癸烯在Ph_2C(Cp-9-Flu)ZrCl_2/MAO催化下聚合产物的结构进行了分析比较。结果表明:在Zr和1-癸烯物质的量之比为10×10~(-5),硼化物和Zr物质的量之比为1.5,Al和Zr物质的量之比为100,反应温度为60℃的条件下,反应时间120 min,1-癸烯的转化率为93.6%,运动黏度(100℃)为3 684 mm~2/s,黏度指数为367,数均分子量为2.9×10~4,分子量分布为1.85;聚合时单体主要进行1,2插入,产生亚乙烯基端基。     

rac-Et(1-Ind)_2ZrCl_2/MAO催化1-癸烯聚合制备高粘度润滑油

茂金属催化体系具有超高活性和单一活性中心,是催化α-癸烯聚合的理想催化剂。用茂金属催化体系rac-Et(1-Ind)2Zr Cl2/MAO对1-癸烯聚合制备高粘度润滑油基础油进行了研究,提出了反应体系可能的聚合机理。考察了催化剂浓度、Al和Zr物质的量之比、反应温度和反应时间对聚合产物性能的影响。结果表明,在Zr和1-癸烯物质的量之比为8×10-5,Al和Zr物质的量之比为100,反应温度为50℃,反应时间为60 min时,1-癸烯的转化率为91.6%。聚合产物的整体性能较为优异,运动粘度(100℃)为393.9 mm2/s,粘度指数为271,数均分子量为9 091,分子量分布为1.691 3。     

乙醇体系中金属离子催化转化人参皂苷Rb1的研究

人参皂苷Rb1是人参中的主要皂苷之一,但人体吸收量极少,而其衍生物Rg3、Rk1、Rg5却易于人体吸收,但其制备和分离成本较高。针对以上问题将人参皂苷Rb1在50%乙醇水溶液体系和无水乙醇体系中进行催化条件的优化,并分析其产物。实验发现,通过对金属离子催化效果的筛选,选取NbCl₅为反应催化剂;在50%乙醇水溶液体系中最优条件下反应,Rg3得率为18.29%;在无水乙醇体系中最优条件下反应,Rg3得率为49.45%。根据两组反应产物的对比,推测在50%乙醇水溶液体系反应时,水可能供给电子基团,并生成更多水合化合物即20(S)-25-OH-Rg3和20(R)-25-OH-Rg3;在无水乙醇体系反应时,电子基团可能无法供给,形成双键,生成其他化合物即Rk1和Rg5。该发现为金属离子催化人参皂苷以制备稀有人参皂苷的方法奠定了理论基础。     

Insect antifeedant properties of anthranoids from the genusVismia

Vismiones and ferruginins, representatives of a new class of lypophilic anthranoids from the genusVismia were found to inhibit feeding in larvae of species ofSpodoptera, Heliothis, and inLocusta migratoria.     

Direct observation of freeze-thaw instability of latex coatings via high pressure freezing and cryogenic SEM

Despite its industrial importance, the subject of freeze-thaw (F/T) stability of latex coatings has not been studied extensively. There is also a lack of fundamental understanding about the process and the mechanisms through which a coating becomes destabilized. High pressure (2100 bar) freezing fixes the state of water-suspended particles of polymer binder and inorganic pigments without the growth of ice crystals during freezing that produce artifacts in direct imaging scanning electron microscopy (SEM) of fracture surfaces of frozen coatings. We show that by incorporating copolymerizable functional monomers, it is possible to achieve F/T stability in polymer latexes and in low-VOC paints, as judged by the microstructures revealed by the cryogenic SEM technique. Particle coalescence as well as pigment segregation in F/T unstable systems are visualized. In order to achieve F/T stability in paints, latex particles must not flocculate and should provide protection to inorganic pigment and extender particles. Because of the unique capabilities of the cryogenic SEM, we are able to separate the effects of freezing and thawing, and study the influence of the rate of freezing and thawing on F/T stability. Destabilization can be caused by either freezing or thawing. A slow freezing process is more detrimental to F/T stability than a fast freezing process; the latter actually preserves suspension stability during freezing. Presented at the 82nd Annual Meeting of the Federation of Societies for Coatings Technology, October 27–29, 2004 in Chicago, IL. Tied for first place in The John A. Gordon Best Paper Competition.     

Ethanol and (−)-α-Pinene: Attractant Kairomones for Bark and Ambrosia Beetles in the Southeastern US

In 2002–2004, we examined the flight responses of 49 species of native and exotic bark and ambrosia beetles (Coleoptera: Scolytidae and Platypodidae) to traps baited with ethanol and/or (−)-α-pinene in the southeastern US. Eight field trials were conducted in mature pine stands in Alabama, Florida, Georgia, North Carolina, and South Carolina. Funnel traps baited with ethanol lures (release rate, about 0.6 g/day at 25–28°C) were attractive to ten species of ambrosia beetles (Ambrosiodmus tachygraphus, Anisandrus sayi, Dryoxylon onoharaensum, Monarthrum mali, Xyleborinus saxesenii, Xyleborus affinis, Xyleborus ferrugineus, Xylosandrus compactus, Xylosandrus crassiusculus, and Xylosandrus germanus) and two species of bark beetles (Cryptocarenus heveae and Hypothenemus sp.). Traps baited with (−)-α-pinene lures (release rate, 2–6 g/day at 25–28°C) were attractive to five bark beetle species (Dendroctonus terebrans, Hylastes porculus, Hylastes salebrosus, Hylastes tenuis, and Ips grandicollis) and one platypodid ambrosia beetle species (Myoplatypus flavicornis). Ethanol enhanced responses of some species (Xyleborus pubescens, H. porculus, H. salebrosus, H. tenuis, and Pityophthorus cariniceps) to traps baited with (−)-α-pinene in some locations. (−)-α-Pinene interrupted the response of some ambrosia beetle species to traps baited with ethanol, but only the response of D. onoharaensum was interrupted consistently at most locations. Of 23 species of ambrosia beetles captured in our field trials, nine were exotic and accounted for 70–97% of total catches of ambrosia beetles. Our results provide support for the continued use of separate traps baited with ethanol alone and ethanol with (−)-α-pinene to detect and monitor common bark and ambrosia beetles from the southeastern region of the US.     

Novel polyurethane coating technology through glycidyl carbamate chemistry

Glycidyl carbamate chemistry combines the excellent properties of polyurethanes with the crosslinking chemistry of epoxy resins. Glycidyl carbamate functional oligomers were synthesized by the reaction of polyfunctional isocyanate oligomers and glycidol. The oligomers were formulated into coatings with several amine functional crosslinkers at varying stoichiometric ratios and cured at different temperatures. Properties such as solvent resistance, hardness, and impact resistance were dependent on the composition and cure conditions. Most coatings had an excellent combination of properties. Studies were carried out to determine the kinetics of the curing reaction of the glycidyl carbamate functional oligomers with multifunctional and model amines. Detailed kinetic analysis of the curing reactions was also undertaken. The results indicated that the glycidyl carbamate functional group is more reactive than a glycidyl ether group. Presented at the 82nd Annual Meeting of the Federation of Societies for Coatings Technology, on October 27–29, 2004, in Chicago, IL.     

Highly moisture-proof polysilsesquioxane coating prepared via facile sol-gel process

A highly moisture-proof polysilsesquioxane coating was obtained from a new bis-silylated precursor, which was synthesized from 3-aminopropyltriethoxysilane (APTES) and m-xylylene diisocyanate (m-XDI) in tetrahydrofuran (THF) and verified by ¹H MAS NMR. For direct comparison purposes, an SiO₂ coating was also prepared by the Stöber method using tetraethoxysilane (TEOS) as the reactant. Interestingly, the coating obtained from the polysilsesquioxane sol exhibited a much higher moisture resistance capability than its counterpart, which was attributed to its more compact feature between nanoparticles as characterized by N₂ absorption experiment and transmission electron microscopy (TEM). Furthermore, its high transparency of about 92% showed potential for application in the protection of optical crystals.