Concentration induced the interfacial self‐assembly polymorphism of 4, 4′‐dihexadecyloxy‐benzophenon by scanning tunneling microscopy

The concentration effect on a two‐dimensional (2D) self‐assembly of 4, 4′‐dihexadecyloxy‐benzophenon (DHB) has been investigated by scanning tunneling microscopy. The self‐assembly of DHB at the phenyloctane/graphite interface was concentration dependent. Under low concentration, the DHB molecules were adsorbed intactly on the graphite surface. With the increasing of concentration, one of side chains connecting the conjugated moiety stretched into the liquid phase. The coexistence of two self‐assembled structures was observed in a moderate concentration. The result indicated that the van der Waals interactions between the molecules and the graphite lattice were decreasing with the increasing concentration. After the samples were placed in ambient conditions over 24 h, a different self‐assembled structure was obtained on the gas/solid interface, in which the DHB molecules were adsorbed on the surface with only one of the side chains. Both the benzophenon core and the other side chain were extended to the gas phase. The results demonstrated that concentration played an important role in forming the 2D molecular self‐assembly and provided an efficient approach for the control of the DHB molecular nanostructure. Copyright © 2013 John Wiley & Sons, Ltd.     

非标记电化学DNA杂交指示剂

电化学DNA杂交检测技术因其快速、灵敏、低消耗和易于操作等优点而在临床医学、环境监测和药物分析等领域受到普遍关注。电化学DNA杂交指示剂是DNA电化学杂交传感器的重要组成部分,能与单链DNA和双链DNA通过不同的模式和作用力进行差异性结合。本文介绍了电化学杂交指示剂的定义及其在DNA电化学传感器中的重要性,根据分子结构上的特征差异,将非标记型电化学杂交指示剂分为有机染料（荧光素）、药物分子和金属配合物三类,并从中选取了各个类型中具有代表性的指示剂对它们的工作原理、研究进展和应用现状进行了比较和评述。对杂交指示剂的设计和开发前景,特别是满足基因芯片应用等方面做出了展望。     

Cross-diffusion induced instability and stability in reaction-diffusion systems

In a reaction-diffusion system, diffusion can induce the instability of a uniform equilibrium  which is stable with respect to a constant perturbation, as shown by Turing in 1950s. We show that cross-diffusion can destabilize  a uniform equilibrium  which is stable for the kinetic and self-diffusion reaction systems; on the other hand, cross-diffusion can also stabilize  a uniform equilibrium which is stable for the kinetic system but unstable for the self-diffusion reaction system. Application is given to predator-prey system with preytaxis and vegetation pattern formation in a water-limited ecosystem.     

中药色谱指纹图谱组分保留时间漂移的校准

基于光谱相关色谱方法判断复杂中药色谱指纹图谱的组分相关性,实现同一中药样本在不同实验条件下所得的色谱指纹图谱的相同组分的色谱保留时间漂移的局部最小二乘校正,为合理评价指纹图谱的品质提供较为实用的工具。     

THE AROMATIZATION MECHANISM OF METHANE OVER Mo/HZSM-5 ZEOLITE CATALYSTS WITHOUT USING OXIDANTS

IntroductionMethancisthcmaJorcomponcntofnaturalgasanditscatalyticconvcrsiontodcsiredchemicalproductsorliquidfiJcIisnotonl}'apromisingapproachtotheutilizationofnaturalgasrcsourccbutalsoagrcatsubjcctforcatalysissciencctt'hichdcaIst"iththcactivationofsmallmolcculesThcx"orldrcscrvcofnaturalgashasbccnexplorcdasaboutl382562xl()8m3IllTheMTGprocessdcvclopedbythcMobilcorpcangctliquidfuelfrommethancthroughsteamreformingofmethanctoproduccsynthcsisgaswhichisassociatedt'ithamaJorityofthecostsofthcprocc…     

MoO_3、NiO、ZnO在小表面金红石上的分散行为

氧化物、盐类在氧化物载体表面的自发分散是一种广泛存在的现象，文献中已报导过大量氧化物和盐类在高比表面载体上分散的研究结果［'－3］TIO。作为一种较新型的载体，与Y－AI。O。、硅胶等传统载体相比，有许多不同特性．活性组分在TIO。表面的分散状态及所得催化剂的性能已有不少报导［'－'］，但所用的TIOZ主要是较高比表面的锐钛矿型TIOZ（刘金红石型TIO。（r）和锐钛矿型TIOZ（a）的结构不同，它是高温生成相，比表面较小［'］．氧化物在金红石上的分散行为仍未见报导．我们制备了三种具有不同比表面的TIO水），系统地研…     

Significant Acceleration of Photocatalytic CO2 Reduction at the Gas-Liquid Interface of Microdroplets**

Solar-driven CO₂ reduction reaction (CO₂RR) is largely constrained by the sluggish mass transfer and fast combination of photogenerated charge carriers. Herein, we find that the photocatalytic CO₂RR efficiency at the abundant gas-liquid interface provided by microdroplets is two orders of magnitude higher than that of the corresponding bulk phase reaction. Even in the absence of sacrificial agents, the production rates of HCOOH over WO₃ ⋅ 0.33H₂O mediated by microdroplets reaches 2536 μmol h⁻¹ g⁻¹ (vs. 13 μmol h⁻¹ g⁻¹ in bulk phase), which is significantly superior to the previously reported photocatalytic CO₂RR in bulk phase reaction condition. Beyond the efficient delivery of CO₂ to photocatalyst surfaces within microdroplets, we reveal that the strong electric field at the gas-liquid interface of microdroplets essentially promotes the separation of photogenerated electron-hole pairs. This study provides a deep understanding of ultrafast reaction kinetics promoted by the gas-liquid interface of microdroplets and a novel way of addressing the low efficiency of photocatalytic CO₂ reduction to fuel.     

A Versatile Naphthalimide–Sulfonamide‐Coated Tetraphenylethene: Aggregation‐Induced Emission Behavior,Mechanochromism, and Tracking Glutathione in Living Cells

A tetraphenylethene (TPE) derivative substituted with a sulfonyl‐based naphthalimide unit ( TPE‐Np ) was designed and synthesized. Its optical properties in solution and in the solid state were investigated. Photophysical properties indicated that the target molecule, TPE‐Np , possessed aggregation‐induced emission (AIE) behavior, although the linkage between TPE and the naphthalimide unit was nonconjugated. Additionally, it exhibited an unexpected, highly reversible mechanochromism in the solid state, which was attributed to the change in manner of aggregation between crystalline and amorphous states. On the other hand, a solution of TPE‐Np in a mixture of dimethyl sulfoxide/phosphate‐buffered saline was capable of efficiently distinguishing glutathione (GSH) from cysteine and homocysteine in the presence of cetyltrimethylammonium bromide. Furthermore, the strategy of using poly(ethylene glycol)–polyethylenimine (PEG‐PEI) nanogel as a carrier to cross‐link TPE‐Np to obtain a water‐soluble PEG‐PEI/ TPE‐Np nanoprobe greatly improved the biocompatibility, and this nanoprobe could be successfully applied in the visualization of GSH levels in living cells.