2-溴苯酚合成工艺的优化研究

2-溴-4-叔丁基苯酚与甲苯的叔丁基转移反应可以形成重要的有机中间体2-溴苯酚。考察了催化剂及反应条件对叔丁基转移反应的影响,结果表明,三氯化铝及其与叔胺盐酸盐的复合盐对叔丁基转移反应的具有较好的催化活性,27AlNMR的分析表明催化活性中心可能是三氯化铝与水解产生的氯化氢反应形成的氯铝酸。进一步研究表明,氯化氢及溴化氢可提高三氯化铝的催化活性,降低三氯化铝的用量。优化后的工艺条件：在二氯甲烷溶剂中,4-叔丁基苯酚与溴素在0℃反应选择性形成2-溴-4-叔丁基苯酚,加入摩尔分数为30%的AlCl3及600%的甲苯,30℃“一锅法”反应制备2-溴苯酚,2-溴-4-叔丁基苯酚反应的转化率及选择性可达96.5%、99.6%。     

宝日褐煤及其干燥煤和半焦的润湿热变化规律

采用μRC微量热仪研究了宝日希勒褐煤及其500℃热解半焦在25℃下的润湿热.结果表明,褐煤的含水量对润湿热有较大影响,含水量低于16%的干燥煤润湿热随着含水量的降低而增加,含水量高于16%的宝日褐煤润湿时的放热量可忽略不计;半焦在空气中由于氧化吸湿,润湿热降低,暴露48h后润湿热降低为原来的1/2,暴露240h后润湿热降为原来的12%,并不再随暴露时间的增加而降低;半焦的润湿热与半焦粒度无关,而润湿时的放热速率随粒度的增大而降低;褐煤的表面官能团与半焦的表面官能团有较大差别.研究表明,表面官能团对润湿热有较大影响.     

The role of introduced isolation groups in PVK-based nonlinear optical polymers: Enlarged nonlinearity, improved processibility, and enhanced thermal stability

In this paper, a new series of PVK-based nonlinear optical (NLO) polymers were successfully synthesized, in which different isolation moieties (from the small to large size) were bonded to the NLO chromophore moieties. All the polymers were well characterized, and the obtained results demonstrated that the polymers exhibited improved solubility and processibility, and good optical transparency upon the introduction of the isolation groups, in addition to the enhanced NLO effects, further confirming that the linkage of isolation groups will not only boost the NLO properties of the resultant polymers to possibly high values, but also improve their processibility during the device manipulation process.     

水泵水轮机“S“特性对机组水头低时发电影响及对策分析

介绍了水泵水轮机“S”特性并从理论上分析了其形成的原因。由于活动导叶与固定导叶的共同作用,抽水蓄能机组水头低时发电,导叶异步开启时,进入转轮前部分水流的流速得到了提高,并高于导叶同步开启时进入转轮前水流的流速。从而有效地改善了对应空载工况点处的“S”特性,解决了水泵水轮机“S”特性此时对机组运行的不利影响。并结合实例进行了分析。     

Preparation of a Novel Class of Cationic Gemini Imidazolium Surfactants Containing Amide Groups as the Spacer: Their Surface Properties and Antimicrobial Activity

A class of novel cationic Gemini imidazolium surfactants containing amide groups as the spacer were synthesized from ethylenediamine and 1-bromoalkane(C₈, C₁₀, C₁₂, C₁₄, C₁₆) by N-alkylation to get N,N′-dialkyl ethylenediamine (1a–e), 1a–e was further reacted with chloroacetyl chloride by N-acylation to get N,N′-(ethane-1,2-diyl)bis(2-chloro-N-alkylacetamide) (2a–e), which was further reacted respectively with 1-methyl imidazole by quaternized to form the surfactant molecule, N,N′-((ethane-1,2-diyl)bis(alkyl-azanediyl)bis(2-oxoethane-2,1-diyl)) bis(1-methyl-1H-imidazol-3-ium) dichloride. The structures of intermediates (1a–e) and (2a–e) were characterized by IR and ¹H NMR. The structures of the surfactants (3a–e) were characterized by IR, ¹H-NMR and ¹³C-NMR and element analysis. The critical micelle concentrations (CMC) of 3a–e were determined by the conductivity method at 25 °C. The CMC values decreased with increasing the length of the hydrophobic chain. The surfactants (3a–e) showed good foaming stability, emulsion ability and wetting ability. The surfactants (3a–e) also have good antimicrobial activity against Staphylococcus aureus, Escherichia coli and Bacillus subtilis.     

REPLACE: a strategy for iterative design of cyclin-binding groove inhibitors

We describe a drug-design strategy termed REPLACE (REplacement with Partial Ligand Alternatives through Computational Enrichment) in which nonpeptidic surrogates for specific determinants of known peptide ligands are identified in silico by using a core peptide-bound protein structure as a design anchor. In the REPLACE application example, we present the effective replacement of two critical binding motifs in a lead protein-protein interaction inhibitor pentapeptide with more druglike phenyltriazole and diphenyl ether groups. These were identified through docking of fragment libraries into the volume of the cyclin-binding groove of CDK2/cyclin A vacated through truncation of the inhibitor peptide-binding determinants. Proof of concept for this strategy was obtained through the generation of potent peptide-small-molecule hybrids and by the confirmation of inhibitor-binding modes in X-ray crystal structures. This method therefore allows nonpeptide fragments to be identified without the requirement for a high-sensitivity binding assay and should be generally applicable in replacing amino acids as individual residues or groups in peptide inhibitors to generate pharmaceutically acceptable lead molecules.     

Water-soluble single-walled carbon nanotubes via noncovalent functionalization by a rigid, planar and conjugated diazo dye

A new noncovalent approach for the dissolution and exfoliation of SWNTs in water by a rigid, planar and conjugated diazo dye, Congo red (CR), is reported. Using a simple physical grinding treatment, the mixture of SWNTs and CR can be dissolved in water with a solubility as high as 3.5 mg/ml for SWNTs. The complete elimination of free CR from the mixture hardly changed this excellent solubility. High-resolution transmission electron microscope images showed that the SWNTs bundles were efficiently exfoliated into individual SWNTs or small ropes, which was further demonstrated by the increased π-plasmon UV-vis absorption and the upshift of the radical breathing mode in Raman scatterings. The π-stacking interaction between adsorbed CR and SWNTs was considered responsible for the high solubility. The uninterrupted structure of SWNTs with CR functionalization was ascertained by the unchanged disorder-induced Raman scattering.     

还原温度对氧化石墨烯的湿度-甲醛交叉敏感性能的影响

以氧化石墨烯溶胶为前体,通过旋涂工艺制备薄膜型气敏元件,在低温80～180℃下进行热处理,获得系列不同还原程度的还原氧化石墨烯气敏元件,采用XRD、AFM、FT-IR、XPS对样品的层结构、薄膜厚度及含氧官能团变化属性进行表征,将气敏薄膜元件在相对湿度为11.3%～93.6%的范围内进行预湿处理,并测定元件对甲醛气氛的敏感性能。结果表明：随热还原处理温度的升高,氧化石墨烯的结构逐渐向类石墨结构转变,含氧官能团逐渐脱失,缺陷增多,薄膜的方块电阻呈数量级地减小,从41 MΩ减小至928 Ω;经不同湿度预处理的气敏元件置于甲醛气氛中产生了水分子与甲醛分子的竞争吸附,从而导致电阻的明显变化;在10^?4甲醛气氛下,未还原或热还原温度较低的气敏元件适用于低、高湿环境下甲醛气氛的气敏测试,最大灵敏度为69.1%,而还原温度适中的元件则适用于中湿环境的甲醛测试,最大灵敏度为80.3%。