Theoretical kinetic study of the reaction between dimethyl disulfide and OH radicals

The potential energy profile of the reaction between dimethyl disulfide and OH^? radicals is explored by utilizing ab initio and hybrid meta density functional theory methods. Having the energies and structural data of the stationary points, statistical rate theories, such as transition state theory and variable reaction coordinate-transition state theory, are employed to compute the overall rate constants, and discuss the mechanism and product channels. On the basis of the calculations, the overall rate coefficient is predicted to be 2.49?×?10^?10?cm³?molecule^?1?s^?1 at 298?K. It is found that in the most favorable pathway, the reaction proceeds via formation of the relatively unstable intermediate CH₃S^?(OH)SCH₃ decomposing rapidly to yield CH₃S^?+CH₃SOH.     

Interaction of triton X-100 on silica: A relationship between surface characteristics and adsorption isotherms

Adsorption of Triton X-100 on various silica substrates has been investigated. A number of solids, including a natural quartz, this quartz washed with HCl acid and subsequently heated at 1273 K; two aerosils and one Kieselgel silicas were studied. These solids exhibit surface areas in the range of 5 to 430 m² g^?1. All the Triton adsorption isotherms display an S-shape at the adsorption temperatures studied (298 and 308 K). It has been found that the pretreatments of natural quartz (by water washing, impurities removed by acid and/or high temperature calcination) affect considerably the amounts of TX-100 adsorbed. Measurements of surface composition have been made by X-ray photoelectron spectroscopy (XPS) with particular emphasis on the presence of impurities and on the number of OH groups at the surface of the samples. The nature of the surface hydroxyl has also been studied by infrared spectroscopy. Furthermore, the specific number of hydroxyl groups on the surface of the silica samples has been determined by thermogravimetric analysis. Finally an attempt to correlate solid surface characteristics with adsorption isotherms has been developed.     

羟基磷灰石涂层人工关节的应用研究

采用人工合成高纯度的羟基磷灰石粉末，喷涂在具有注册证的钛合金和钴铬钼合金人工关节上。通过生物学基础检测、动物实验和临床试用，证明所制作的各种羟基磷灰石涂层人工关节，能诱发骨质生长，起生物固定作用，对治疗丧失功能的骨胳效果甚佳。     

过渡金属元素催化羟自由基反应机理研究

针对显色剂－过渡金属元素－过氧化氢体系，用分光光度法间接测定羟自由基。通过大量试验，确定了三苯甲烷类酸性酚醌吡喃类为有效显色剂，并确定了溴邻苯三酚红－亚铁离子－过氧化氢体系测定羟自由基的最佳条件，首次推测出其最可能的反应机理为：亚铁离子催化过氧化氢产生羟自由基，羟自由基氧化溴邻苯三酚红上的羰基碳氧双键，破坏其显色的共轭结构，使其褪色，此法可作为筛选羟自由基清除剂的有效方法。     

The Antithrombotic Agent Pterostilbene Interferes with Integrin αIIbβ3-Mediated Inside-Out and Outside-In Signals in Human Platelets

Platelets play a crucial role in the physiology of primary hemostasis and pathological processes such as arterial thrombosis; thus, developing a therapeutic target that prevents platelet activation can reduce arterial thrombosis. Pterostilbene (PTE) has remarkable pharmacological activities, including anticancer and neuroprotection. Few studies have reported the effects of pterostilbene on platelet activation. Thus, we examined the inhibitory mechanisms of pterostilbene in human platelets and its role in vascular thrombosis prevention in mice. At low concentrations (2–8 μM), pterostilbene strongly inhibited collagen-induced platelet aggregation. Furthermore, pterostilbene markedly diminished Lyn, Fyn, and Syk phosphorylation and hydroxyl radical formation stimulated by collagen. Moreover, PTE directly hindered integrin α_IIbβ₃ activation through interfering with PAC-1 binding stimulated by collagen. In addition, pterostilbene affected integrin α_IIbβ₃-mediated outside-in signaling, such as integrin β₃, Src, and FAK phosphorylation, and reduced the number of adherent platelets and the single platelet spreading area on immobilized fibrinogen as well as thrombin-stimulated fibrin clot retraction. Furthermore, pterostilbene substantially prolonged the occlusion time of thrombotic platelet plug formation in mice. This study demonstrated that pterostilbene exhibits a strong activity against platelet activation through the inhibition of integrin α_IIbβ₃-mediated inside-out and outside-in signaling, suggesting that pterostilbene can serve as a therapeutic agent for thromboembolic disorders.     

流动注射化学发光法测定噻枯唑

研究发现,在pH为2～3的范围内,Fe3 和过氧化氢反应产生的羟基自由基(·OH)可以氧化噻枯唑产生较弱的化学发光,罗丹明6G可以大大增强此发光,且增加的发光强度与噻枯唑的质量浓度在一定范围内呈良好的线性关系,由此建立了测定噻枯唑的流动注射化学发光新方法。该法的检出限为19μg/L(3σ),线性范围为0.03～5.0mg/L,对3.0mg/L的噻枯唑连续平行测定11次,其相对标准偏差(RSD)为3.1%。该法已成功测定了环境水样和大米中加入的噻枯唑含量,结果令人满意。     

IR study of the interaction of hydroxyl groups of silica gel with Cr species of Phillips' type catalysts

Spectroscopic evidence for the interaction of hydroxyl groups and chromium ions was obtained using a catalyst prepared from chromyl chloride. A new OH peak, observed at 3705 cm^–1 after pumping away CO gas, is attributed to the direct interaction of OH with the low-valent chromium. This peak shifts to 3590 cm^–1 on contact with O₂ at room temperature and it is assigned to a hydroxyl interacting with the oxidized chromium. New assignments are also proposed for IR bands of CO presorbed on the catalyst. The peak due to CO at 2188 cm^–1 decreases as the OH intensity at 3705 cm^–1 increases, suggesting that the former peak arises from adsorption on Cr(II) species to which two oxygen atoms are attached.     

Cu（II）掺杂纳米TiO2的制备及其应用研究

本文利用水热法制备了Cu(II)掺杂的纳米TiO2，并用X射线衍射分析仪(XRD)和扫描电镜(SEM)对其进行了表征。将该材料固定于球形分子筛表面作为催化剂，在流动式圆筒反应器中对罗丹明6G(R-6G)和印染污水进行处理，表现出优良的光催化性能。     

固体超强酸催化合成对羟基苯甲酸乙酯的研究

以固体超强酸ＳＯ４２－／ＴｉＯ２为催化剂，４Ａ分子筛作脱水剂，合成了对羟基苯甲酸乙酯。应用该方法，酯化反应产率高达８４％，同时对影响产率的诸因素进行了考察，其最佳反应条件为：醇酸摩尔比４∶１，催化剂用量９％，反应时间３ｈ，反应温度１１５～１３５℃。