WO3/SiO2催化剂上2-丁烯与乙烯歧化制丙烯

采用浸渍法制备了WO₃/SiO₂催化剂,对其进行了UV-Vis DRS和NH₃-TPD表征。将WO₃/SiO₂作为催化剂,以乙烯和2-丁烯为原料制备丙烯,考察了反应温度、质量空速等因素对歧化反应的影响。实验结果表明,催化剂的最佳WO₃担载量为8 %;以8%WO₃/SiO₂ 为催化剂,在反应温度473K~573K、压力3.0MPa、质量空速1.6h^-1下,2-丁烯的转化率可保持在80%以上,丙烯的选择性大于89.2%。经过140h的稳定性实验,2-丁烯的转化率和丙烯的选择性略有下降,适当的提高反应温度（由473K增加到513K）可以恢复催化剂的活性。新鲜催化剂表面存在四面体、八面体六价钨物种和体相WO₃,适当还原的W物种是歧化活性物种;W负载在催化剂表面引入了新的强酸中心,同时明显增加了总酸量。     

纳米颗粒水基分散液在岩心微通道中的双重减阻机制及其实验验证

提出了纳米颗粒水基分散液的力学-化学双重减阻机制,并通过对比岩心切片吸附纳米颗粒前后以及冲刷前后的表面微结构、润湿性的变化,进行了实验验证. 研究结果表明,经纳米颗粒水基分散液处理之后的岩心切片表面表现为强亲水性, 并且存在一层致密的纳米颗粒吸附层;冲刷之后岩心切片表面的纳米颗粒吸附层依然存在, 但其表面已逐渐转变为强/超疏水性,反映了纳米颗粒吸附层表面的表面活性剂被逐渐清洗干净. 注水初期,主要表现为表面活性剂的化学减阻作用.随着注水过程的进行, 主要体现为以疏水表面的滑移效应为主的力学减阻机制.岩心驱替实验结果表明, 纳米颗粒水基分散液驱替后的岩心的水相渗透率平均提高幅度达84.3%, 减阻效果显著,证实了纳米颗粒水基分散液的力学-化学双重减阻机制.     

Large Slip Length over a Nanopatterned Surface

A thermodynamic method is employed to analyse the slip length of hydrophobic nanopatterned surface. The maximal slip lengths with respect to the hydrophobicity of the nanopatterned surface are computed. It is found that the slip length reaches more than 50 μm if the nanopatterned surfaces have a contact angle larger than 160°. Such results are expected to find extensive applications in micro-channels and helpful to understand recent experimental observations of the slippage of nanopatterned surfaces.     

Salvihispin A and its glycoside,two neo-clerodane diterpenoids with neurotrophic activities from Salvia hispanica L.

A neo-clerodane diterpenoid, salvihispin A (1), as well as its glycoside, salvihispin A-2-O-β-d-3-keto-glucopyranoside (2) were isolated from the aerial parts of Salvia hispanica. Compound 2 possessed an unusual 3-keto-glucopyranoside moiety. Their structures and absolute configurations were elucidated by extensive spectroscopic methods and confirmed by single crystal X-ray diffraction. Salvihispin A (1) and its glycoside (2) enhanced the neurite outgrowth of NGF-mediated PC12 cells at a concentration of 10?μM.     

毛细管电泳化学发光检测系统新进展

分析技术的微型化、集成化和自动化是当前分析化学发展的一个新趋势。本文综述了毛细管电泳化学发光检测系统微型化、集成化和自动化的最新研究进展。