The importance of bulk Ti3+ defects in the oxygen chemistry on titania surfaces

The role of bulk defects in the oxygen chemistry on reduced rutile TiO(2)(110)-(1 × 1) has been studied by means of temperature-programmed desorption spectroscopy and scanning tunneling microscopy measurements. Following O(2) adsorption at 130 K, the amount of O(2) desorbing at ～410 K initially increased with increasing density of surface oxygen vacancies but decreased after further reduction of the TiO(2)(110) crystal. We explain these results by withdrawal of excess charge (Ti(3+)) from the TiO(2)(110) lattice to oxygen species on the surface and by a reaction of Ti interstitials with O adatoms upon heating. Important consequences for the understanding of the O(2)-TiO(2) interaction are discussed.     

Transition metal complexes on mesoporous silica nanoparticles as highly efficient catalysts for epoxidation of styrene

We have synthesized a series of catalysts for epoxidation of styrene by immobilizing salicylaldimine transition metal (copper, manganese, and cobalt) complexes on mesoporous silica nanoparticles (MSNs) with diameters of 120-150 nm. The prepared catalysts are characterized by infrared (IR) spectra, thermal gravimetric analyses (TGA), inductively coupled plasma (ICP), CHN elemental analysis, nitrogen adsorption-desorption, scanning electron microscopy (SEM), and transmission electron microscopy (TEM). These catalysts possess excellent catalytic efficiency in epoxidation of styrene when using tert-BuOOH (TBHP) as oxidant. Styrene shows a high conversion (～99%) as well as epoxide selectivity (～80%) over Cu-MSN catalysts, and high conversion (～99%) and moderate epoxide selectivity (～65%) over Mn-MSN and Co-MSN catalysts. The recycling experiment results indicate that these catalysts maintain catalytic activity even after being used for three cycles. Our results indicate that MSNs can serve as better catalyst supports.     

A simple and sensitive CE method for the simultaneous determination of catecholamines in urine with in-column optical fiber light-emitting diode-induced fluorescence detection

A simple and sensitive method has been developed for simultaneous analysis of three catecholamines: dopamine (DA), epinephrine (EP) and norepinephrine (NE) in urine by capillary electrophoresis (CE) coupled with in-column fiber-optic light-emitting diode-induced fluorescence detection (ICFO-LED-IFD). Fluorescein isothiocyanate was used as the fluorescence tagged reagent for derivatization of DA, EP and NE. The CE conditions for separation of these catecholamines were systematically investigated. It was found that catecholamines could be more effectively separated by adding β-cyclodextin (β-CD) and acetonitrile (ACN) to a background electrolyte (BGE) of sodium borate. The migration times are 10.61, 10.83 and 11.14 min for DA, EP and NE, respectively and the catecholamines are completely separated within 11.5 min under the optimal condition of a BGE containing 10% v/v ACN, 20 mM β-CD and 20 mM sodium borate (pH 9.5), and an applied voltage of 13 kV. The relative standard deviations of migration time and peak area for these catecholamines are less than 0.16 and 2.0%, respectively. The limit of quantifications (LOQs) for DA, EP and NE are 3.5, 1.0 and 3.1 nM whereas the limit of detections (LODs) for DA, EP and NE are 1.0, 0.3 and 0.9 nM, respectively. Our proposed CE method provides low LOQ and LOD values. This CE-ICFO-LED-IFD methodology has been successfully applied to analyze catecholamines in human urine samples with good accuracy and satisfactory recovery.     

功率因数校正Boost变换器中快时标不稳定的形成与参数动态共振

以动态调整过程中的动态特征系数积和动态镇定能力为基础,研究连续峰值电流模式功率因数校正(PFC) Boost变换器中的快时标不稳定及其不对称混沌现象的形成机理.基于提高功率因数和降低谐波失真的要求,提出输入电流正弦化的补偿思路,应用参数共振优化补偿策略,推导优化补偿的表达式,采用最强参数共振进行全局优化.数值仿真表明这种全局优化补偿策略具有最强的动态镇定能力,保证每个频闪周期内的快速稳定,控制了快时标不稳定混沌现象,获得理想的补偿效果和单位功率因数,可提高变换器的转换效率. 关键词： Boost变换器 功率因数校正 快时标不稳定 参数共振     

Observation of two multiwave mixing processes via dual optical pumping channels

Based on double optical pumping channels,we experimentally study the competition between two coexistent six-wave mixing(SWM) processes falling into two electromagnetically induced transparency windows by scanning the frequency of the probe field in two similar five-level atomic systems of 85Rb.By blocking one optical pumping channel unrelated to the four-wave mixing(FWM) process,one SWM process,together with the FWM process,generated by a conjugated small-angle static grating could be observed in the spectrum.Moreover,the other SWM process obtained by blocking the first SWM channel is also observed together with the FWM process in a lower N-type four-level subsystem.These experimental results agree well with theoretical predictions.     

电场作用下P掺杂硅烯选择性吸附CH_4的第一性原理计算

在煤层气中选择性吸附和捕捉甲烷分子,对提高煤矿安全具有十分重要的意义.本文采用第一性原理计算的方法,研究了外加电场作用下P掺杂硅烯对甲烷分子的选择性吸附性能.结果表明:正电场作用下,P掺杂硅烯与甲烷分子之间产生较强的化学吸附,能够快速捕获甲烷分子.当关闭外加电场时,P掺杂硅烯与甲烷分子之间则为微弱的物理吸附,甲烷分子很容易实现脱附.同时还发现,外加电场作用下,P掺杂硅烯与氮气、氧气及水之间的吸附均属于物理吸附,表明P掺杂硅烯可以在这些混合气体中实现甲烷气体的选择性吸附. P掺杂硅烯有望成为选择性好的甲烷传感、捕获新材料.     

可同时测量蔗糖浓度和温度的组合光纤光栅传感器

为了实现蔗糖溶液浓度与温度的同步精确测量,采用组合式光纤光栅,通过线性折射率分区,构成相应的系数矩阵。首先,基于模式耦合理论,采用光纤布拉格光栅（FBG）和长周期光纤光栅（LPBG）形成组合式光纤光栅,实现了双参数测量的光学传感器。此组合式光纤光栅结构中,FBG响应温度测量,LPFG同时响应蔗糖溶液浓度和温度测量。然后,在两个线性折射率范围,即1.33~1.42和1.42~1.44中,校正温度和蔗糖溶液浓度的相关系数。最后,构成两个敏感系数矩阵,来讨论蔗糖溶液浓度和温度同时测量的方法。实验结果表明：蔗糖溶液浓度测量灵敏度达到-213.5 pm/RIU,温度测量灵敏度达到117.9 pm/K。因此,组合式光纤光栅传感器作为光化学传感器具有高灵敏度的特性。     

由Srivastava-Khairnar-More算子定义的$p$叶函数类的包含关系

In the present paper, we use the methods of differential subordination and convo- lution to investigate some inclusion properties for certain classes of p-valent analytic functions in the open unit disk, which are associated with the Srivastava-Khairnar-More operator. The results presented here include several previous known results as their special cases.     

Synthesis,Crystal Structure,and Properties of a Dinuclear Cu(I) Cluster

Abstract

A new dinuclear copper(I) cluster complex, [(o-Tol)₃PCuI₂CuP(o-Tol)₃(DMF)] (1) ((o-Tol)₃P = tris(2- methylphenyl)phosphine, DMF = N, N′-dimethylformamide), has been synthesized and the crystal structure was determined by a single-crystal X-ray diffraction study. The dinuclear copper(I) cluster molecule containing an asymmetric Cu₂I₂P₂O core and the dinuclear clusters are fused together by a strong π–π stacking interaction to form asupramolecular one-dimensional (1D) chain. After having compared the relevant complexes composed of CuI and monodentate triarylphosphine ligands, the impact of the substituent of the triarylphosphine ligand to the subsequent complex structure has also been discussed.Except for a strong π–π* bond, the complex 1 also exhibits a weak metal-to-ligand charge transfer (MLCT) absorption bond in the 430–530-nm region and displays a weak green-yellow emission when irradiated by ultraviolet (UV) light. The thermogravimetric analysis demonstrates that its thermal stability is good, and the corresponding PXRD analysis has revealed that the final, organic-free decomposed product is CuI.