Optimization of a Cryogenic System at Temperature 2 K for the PKU-FEL Facility

The conceptual design of a cryogenic system at temperature 2 K for the Peking University Free Electron Laser （PKU-FEL） facility is carried out. In order to minimize the scale of the cryogenic system and the running cost, the superconducting accelerator and the superconducting injector will mainly run at a long-pulsed mode. Optimization of the 2-K cryogenic system is carried out based on the heat load estimation and running parameters. Total cooling power of 52.5 W for the long-pulsed mode is necessary for the PKU cryogenic system. The PKU cryogenic system will be the first 2-K system for accelerators in China and will provide experience for similar facilities.     

Combinational simulations of free energy of polymer solution

It is conceptually proposed that the total entropy of polymer solution is contributed from two distinct parts: the positional and the oomformational. The former can be represented analytically, while the latter can be simulated with the random self-avoiding walk model on the simple cubic lattice for multichain systems. The obtained results indicated that both the conformational entropy and the mixing heat are consistent with the scaling laws wry well.     

A Convenient Method for the Stereoselective Synthesis of 7αHydroxycholesterol

7-Hydroxyderivativesofcholesteroldisplayawidevarietyofbiologicalactivities'-',mostofwhicharerelatedtothephysiologicalcontrolofcholesterolbiosynthesisandantitumoractivity.Inearlyreports',the7-hydroxycholesterolswerepreparedbythesequenceofacetylation,allylicchromicoxidation,andhydridereduction.Generally,theproductisamixtureof7a-and76-epimerswhichisdifficulttobeseparated.V.Kumaretal5improvedthisprocedurebyusingstereospecificreducingreagentsinsteadofthesimplehydride.7a-and7o-epimerscouldbeobtained…     

天然气和氧偶联制环氧乙烷催化剂的反应性能

研制了天然气和氧经偶联反应制环氧乙烷的Ａｇ－Ｂａ－Ｃｓ／Ａｌ２Ｏ３催化剂（ＮＥＯ－１）。用Ｎ２＋Ｏ２＋Ｃ２Ｈ４和偶联产物气加氧作原料气，在２５０℃，空速２５００ｈ＾－１时，乙烯转化率和ＥＯ选择性分别达到了３０％和８０％，ＮＥＯ－１催化具有适宜的比表面和孔结构，用ＸＰＳ分析发现，与新鲜的催化相比，经活化和反应后的催化剂表面的Ｂａ，Ｃｓ原子浓度增高，并具有较多的吸附氧物种。     

高强度高电导率聚乙炔的合成——醚类溶剂的结构对性能的影响

通过选用不同醚类结构做溶剂加热回流Ti(OBu)_4-AIEt_3催化剂,并采用非溶剂聚合方法进行乙炔聚合发现,所得HPPA膜的强度和电导率都有了较大提高。其中直链醚制得的PA膜强度(抗张强度大于100MPa)和空气稳定性比用环醚得到的PA膜高得多,但用前者时的乙炔聚合速率远低于后者。两体系得到的HPPA膜的碘掺杂电导率值相近(～10~3S/cm),拉伸后可达10~4S/cm量级。SEM、TEM及IR光谱的结果表明,不同醚制得的PA膜的纤维束直径及顺式含量有较大差别。     

四（五氟化苯基）卟啉氯化铁选择催化氧化超临界丙烷的反应机理

 以BHT为自由基捕捉剂，研究了四（五氟化苯基）卟啉氯化铁（Ⅲ）将超临界丙烷高选择性催化氧化为丙醇的反应机理．通过GC－MS分析发现，反应产物中有PBHT，故可认为在超临界丙烷氧化反应过程中有丙基自由基存在，初步推断反应涉及自由基机理．同时发现高浓度BHT抑制反应，低浓度BHT促进反应的现象，而以戊烷为底物时没有促进作用．这是由于BHT的位阻效应所致．并对BHT存在时超临界丙烷氧化反应机理进行了初步的推断．     

Molecular Spectroscopic Study on the Interaction between Heparin and Neutral Red

The interaction between heparin and neutral red was investigated by molecular spectroscopic methods. The change of all spectra suggested that positively charged neutral red had interacted with negatively charged heparin. The study of influence factors indicated that electrostatic force and hydrophobic bond might be involved in the interaction. The total binding number per disaccharide unit and intrinsic binding constant were obtained using Scatchard model.     

海螵蛸入药部分和废弃部分8种无机元素分析

为合理开发利用海螵蛸 ,用原子吸收分光光度法测定了海螵蛸中入药部分和废弃部分中8种人体必需无机元素含量。结果表明 ,入药部分和废弃部分中钙含量丰富 ,分别达到 742 1 3× 1 0 - 3和 65 9 76× 1 0 - 3。入药部分铜、铁含量较废弃部分高 ,分别为 9 41× 1 0 - 6 、 91 86× 1 0 - 6 和2 3 5× 1 0 - 6 、 2 5 7× 1 0 - 6 。废弃部分含锌丰富 ,为 3 5 3 62× 1 0 - 6 ,数倍于入药部分 64 65× 1 0 - 6 。可见海螵蛸入药部分和废弃部分均具有良好的开发前景     

Synthesis and Characterization of ChiralLiquid Crystal CMPPCDP

ＳｙｎｔｈｅｓｉｓａｎｄＣｈａｒａｃｔｅｒｉｚａｔｉｏｎｏｆＣｈｉｒａｌＬｉｑｕｉｄＣｒｙｓｔａｌＣＭＰＰＣＤＰＴＩＡＮＹａｎ－ｑｉｎｇ，ＺＨＡＯＹｉｎｇ－ｙｉｎｇ，ＳＵＦｅｎｇ－ｙｕａｎｄＴＡＮＧＸｉｎ－ｙｉ（ＤｅｐａｒｔｍｅｎｔｏｆＣｈｅｍｉｓｔ...     

二水·2-羰基丙酸水杨酰腙合铜(Ⅱ)配合物的晶体结构及生物活性

在水中,以2-羰基丙酸水杨酰腙与硫酸铜反应,制得新配合物Cu(C₁₀H₈N₂O₄)(H₂O)₂(C₁₀H₈N₂O₄^2-为2-羰基丙酸水杨酰腙负离子),并以水为溶剂培养了单晶,测试了晶体结构,该单晶为深绿色,属单斜晶系,空间群为C2/c,晶胞参数a=1.1297(1)nm,b=0.9824(8)nm,c=2.1973(3)nm,β=91.91(8)°,V=2.43749(8)nm³,Z=8,μ=1.817mm^-1,D_c=1.743Mg·m^-3,F(000)=1304,R=0.0264,wR=0.0654,GOF=1.052。其测试结果表明在配合物中Cu²⁺处于五配位的四方锥配位环境,配位原子分别来自1个三齿配体2-羰基丙酸水杨酰腙负二价离子的2个O原子和1个N原子,2个水分子中的O原子,其中1个水分子的O原子处于四方锥的锥顶,锥底的配位原子基本处于同一平面上。对该配合物所作的皿内抑菌试验和盆栽活体实验表明,配合物对小麦条锈病、白菜黑斑病及辣椒疫霉菌等分别有96%、89%、100%的抑制率,且有一定的助长作用。