NiZSM-5沸石上金属镍的分散性

金属的催化活性不仅取决于该金属的价态分布,电子结构,而且强烈地依赖于金属的分散性。载Ni沸石体系,由于金属离子的难还原性和还原金属粒子的流动性,在制备过程中不可避免会引起粒子的迁移,聚集,并形成大晶粒,甚至导致金属的双分散系。迄今为止,关于金属粒子的聚集或大晶粒的形成尚无一致看法。     

Synthesis and Catalytic Asymmetric Reaction of Chiral Pyridine Prolinol Derivatives

The enantioselective reduction of prochiral ketones with borane in the presence of a chiral ligand leading to enantiomerically pure secondary alcohols has received considerable attention in recent years. [1] Enantiomerically pure secondary alcohols are important intermediates for the synthesis of various other organic compounds such as halides, esters, ethers, ketones and amines. To the best of our knowledge, the use of pyridine prolinol derivatives in the reduction of ketones has not been reported so far. Thus, it should be of interest to investigate the catalytic a bility of such ligands. We have an ongoing project in the synthesis and application of chiral pyridine derivatives in chiral molecular recognition[2] and we want to evaluate the effect resulting from the introduction of a pyridinyl moiety onto the catalysts. We expect that the cooperation of pyridine unit and chiral prolinol unit in new ligands may result in unique properties for catalytic reaction.     

Effects of sugar inhibition on cellulases and β-glucosidase during enzymatic hydrolysis of softwood substrates

A quantitative approach was taken to determine the inhibition effects of glucose and other sugar monomers during cellulase and β-Glucosidase hydrolysis of two types of cellulosic material: Avicel and acetic acid-pretreated softwood. The increased glucose content in the hydrolysate resulted in a dramatic increase in the degrees of inhibition on both β-Glucosidase and cellulase activities. Supplementation of mannose, xylose, and galactose during cellobiose hydrolysis did not show any inhibitory effects on β-Glucosidase activity. However, these sugars were shown to have significant inhibitory effects on cellulase activity during cellulose hydrolysis. Our study suggests that high-substrate consistency hydrolysis with supplementation of hemicellulose is likely to be a practical solution to minimizing end-product inhibition effects while producing hydrolysate with high glucose concentration.     

生物金属与胆固醇相互作用的经验势函数计算

流行病学调查和医学实验均证实，以胆固醇在动脉血管壁沉着、形成病灶及纤维增生使管壁变硬为特征的动脉粥样硬化（AS），与血中某些金属元素的水平密切相关＊．一些临床医学观测报道了冠心病患者血中金属元素铜、锌、铬、钢等的水平与胆固醇含量变化的关系［2－6］，以期通过改善人体内微量元素的失调来抑制AS的发生和发展．AS患者血中生物金属铜、锌、铬、锅水平与胆固醇含量有关，可能意味着两者存在某种相互作用制约关系．本文通过金属一胆固醇间、胆固醇分子间、受金属离子影响的胆固醇分子间的各种模型构造，选用恰当的经验势函数…     

简便快速的硫化氢测定法

本文提出了有一种简易快速测定剂来测定水样中的硫化氢的方法。该法的检出限为０．１ｍｇ／Ｌ，对１．０１ｍｇ／Ｌ的Ｈ２Ｓ样品７次测定的相对标准偏差＜４．１％，１ｈ能测定１２个样品。用本测定了几种水样中的Ｈ２Ｓ含量，回收率为８４％－１０５％。应用它可上标准法的４ｈ左右缩短到５ｍｉｎ；使分析成本降低９／１０；不需配制一系列分析试剂和仪器，只需一支小型塑料管和几片药片，便于渔业水质和环境水质的野外现场监测。     

八配位钇(Ⅲ)-反式-1,2-环己二胺四乙酸配合物NH4[Y(trans-CYDTA)(H2O)2]·4.5H2O的合成及分子结构

In this paper, the molecular and crystal structures of the NH₄[Y(trans CYDTA)(H₂O)₂]·4.5 H₂O(trans-CYDTA=trans 1,2-cyclohexanediaminetetraacetic acid) are reported. The crystal data are as follows: Triclinic system, P1space group,a=0.8599(6)nm,b=1.0021(7)nm,c=1.4370(9)nm,α =88.095(13)°,β =75.559(1)°,γ =88.344(12)°,V=1.1981(14)nm³,Z=2, M=708.68,D_c=1.570g· cm^-3, μ =2.506mm^-1 and F(000)=590. The final R₁ and wR₂ are 0.0571 and 0.1350 for 4205 [I >2.0σ (I)] unique reflections and 0.1007 and 0.1615 for all 4981 reflections, respectively. In the title complex, the anion [Y(trans-CYDTA)(H₂O)₂]^- has an eight coordination structure with distorted square antiprism. The trans CYDTA which acts as a hexadentate ligand with four Oatoms and two Natoms and two H₂O molecules directly coordinate to central metal Y(Ⅲ) ion. It can be known that the Y(Ⅲ) ion can form an eight coordinate compound with aminopolycarboxylic acid ligands in addition nine coordination structure.     

Rapid Fabrication of Hollow SiO2 Spheres with Novel Morphology

The hydrolysis of tetraethoxysilane (TEOS) occurred on the surface of poly(methyl methacrylate) (PMMA) microshperes immediately after these microshperes were prepared in TEOS. Micron-sized hollow SiO2 spheres were obtained by calcination of the coated PMMA microshperes. It was found that the final hollow spheres were constituted by small SiO2 particles.     

毛细管电泳法快速分离和检测肠毒性大肠杆菌

 建立了快速分离和检测引起仔猪腹泻的肠毒性大肠杆菌K88、K99和 987P细菌细胞的毛细管区带电泳方法 ,并进行了腹泻仔猪粪便中肠毒性大肠杆菌的应用检测分析。结果表明 ,在电泳缓冲液为 0 0 5mol/LNa2 CO3 NaHCO3(pH 9 9)、分离电压为 1 4 1kV、检测波长为 2 1 0nm的电泳条件下 ,E coliK88、K99和 987P的细胞分别具有单一、稳定的特征谱峰 ,其保留时间的相对标准偏差RSD≤ 0 9% ;在确定的实验条件下 ,实现了腹泻仔猪粪便中肠毒性大肠杆菌的快速检测分析 ,发现将出生 5d～ 6d的腹泻仔猪粪便引入培养基中增殖后主要检出K88。     

Pd-Rh型国Ⅲ排放三效催化剂的研制

对满足欧Ⅲ排放限值的Pd-Rh型三效催化剂进行研究开发,测试了新鲜催化剂的空燃比特性和起燃温度特性,并与市场上的欧Ⅲ催化剂在同等条件下老化后的性能进行了比较.对研制的催化剂进行封装总成后,按照GB18352.3-2005标准进行了常温冷起动Ⅰ型和低温冷起动IV型试验,测试结果完全能满足该标准的限值要求.     

新颖的二维超分子化合物[CoⅢ(aea)(2,2''''-bipy)]Cl·H2O的水热合成及结构表征

0IntroductionInrecentyearsgreatattentionhasbeenpaidtosupramolecularchemistryandawidevarietyofnet鄄workshavealreadybeenconstructedbasedupontheprincipleofcrystalengineering[1~3].Usually,variousmultifunctionalorganicligands,bothrigidandflexiblemulticarboxyli…