液体可视图象序列中杂质小目标的检测方法

在分析红外图象和视图象差异的基础上，研究了一种适用于可视图像序列的运动小目标检测算法。受目标影响的象素点具有较弱的时间相关性，即相对普通象素点有较大的时间方差，根据此特征，用管道更新的方法产生新方差图象序列，再用管道更新的方法累积，增加信噪比，然后用基于统计均值的自适应门限方法分割出目标，最后将原图象的梯度倒数作为象素点强度的加权，有效地抑制灰度突变边界的传感器噪音，保存目标点。     

HPLC determination of ferulic acid in rat plasma after oral administration of Rhizoma Chuanxiong and its compound preparation

An HPLC method is described for determination of ferulic acid in rat plasma. The concentration of ferulic acid in rat plasma was determined after deproteinization with acetonitrile using sulfamethoxazole as internal standard. Chromatographic separations were performed on a C(18) stationary phase with a mobile phase composed of acetonitrile-water (16:84, v/v) with 1% glacial acetic acid. The UV detection wavelength was set at 320 nm. The method was successfully applied to the determination of pharmacokinetic parameters in rat plasma after oral administration of Rhizoma Chuanxiong and and its compound preparation Suanzaoren decoctions. The calibration curve was linear over the range 0.0510-4.08 micro g/mL in rat plasma. Within-day and between-day precisions were less than 4.5% RSD. Mean recovery was determined as 96.9%. The limit of quantitation was 0.0510 micro g/mL. The pharmacokinetic parameters of the two preparations were different significantly (p < 0.05), which may attribute to the effects of other ingredients present in Suanzaoren decoction.     

Structures, relative stability and dissociation of [Si,N,C,O]2+ isomers

Fifteen isomers of [Si,N,C,O]²⁺ system are obtained at UB3LYP/6-311G(d) and UCCSD(T)/6-311+G(2df) (single-point) levels. The analyses are made for predicting the structures of optimized isomers, while ionic fragments with lower energies are suggested. The calculated results indicate that linear isomer SiNCO²⁺(²Π) is thermodynamically the most stable species in [Si,N,C,O]²⁺ system, followed by linear SiOCN²⁺ (²Π), SiCNO²⁺ (²Π), and SiC(NO) (²A) with NCO three-membered ring. The order of stability of several kinetically stable isomers is SiNCO²> SiCNO²⁺ (²Π)>SiOCN²⁺>SiC(NO)²⁺>OSiNC²⁺ (²Π). The obtained results by analyzing the isomerizations and ionic fragment patterns show that the signal peaks of [Si,N,C,O]²⁺ are attributed to the contribution of linear SiNCO²⁺ species, which is metastable and can dissociate to the ionic fragments in the mass spectrometry experiments.     

X-ray Photoelectron Spectroscopy of Imidazolium-Based Zwitterions: The Intramolecular Charge-Transfer Effect

Russian Journal of Physical Chemistry A - We investigate the imidazolium-based zwitterions, 1-butyl-3-methylimidazolium-2-pentafluorophosphate, together with 1-butyl-3-methylimidazolium...     

Improved molten salt synthesis and structure evolution upon cycling of 0.5Li2MnO3·0.5LiCoO2 in lithium-ion batteries

The Li-rich cathode material Li_1.2Co_0.4Mn_0.4O₂(=0.5Li₂MnO₃·0.5LiCoO₂) was prepared by an improved molten salt method. The effects of sintering temperature and time on the physical and electrochemical properties of Li_1.2Co_0.4Mn_0.4O₂ were investigated. With increasing sintering temperature, excellent crystallinity and a stable structure are obtained, which lead to excellent electrochemical properties. However, the sample sintered at 900 °C has poor performance because its large powder diameter prolongs the transportation length of Li⁺ ions. Higher specific surface areas are obtained when samples are sintered at 850 °C for a shorter time, which leads to more activity and excellent charge/discharge capacity. The evolution of a derivative peak at about 3.0 V in the differential capacity (dQ/dV) curves is observed along with the formation of a spinel-like phase, which is verified by analysis using a high-resolution transmission electron microscope. Therefore, it is a simple and quick method to characterize the structure evolution upon cycling of Li-rich cathode materials by means of analysis of the derivative peak.     

Metal–Organic Framework Membrane Nanopores as Biomimetic Photoresponsive Ion Channels and Photodriven Ion Pumps

Biological ion channels and ion pumps with sub-nanometer sizes modulate ion transport in response to external stimuli. Realizing such functions with sub-nanometer solid-state nanopores has been an important topic with wide practical applications. Herein, we demonstrate a biomimetic photoresponsive ion channel and photodriven ion pump using a porphyrin-based metal–organic framework membrane with pore sizes comparable to hydrated ions. We show that the molecular-size pores enable precise and robust optoelectronic ion transport modulation in a broad range of concentrations, unparalleled with conventional solid-state nanopores. Upon decoration with platinum nanoparticles to form a Schottky barrier photodiode, photovoltage across the membrane is generated with “uphill” ion transport from low concentration to high concentration. These results may spark applications in energy conversion, ion sieving, and artificial photosynthesis.     

Energy‐dependent normal and unusually large inverse chlorine kinetic isotope effects of simple chlorohydrocarbons in collision‐induced dissociation by gas chromatography‐electron ionization‐tandem mass spectrometry

Kinetic isotope effects (KIEs) occurring in mass spectrometry (MS) can provide in‐depth insights into the fragmentation behaviors of compounds of interest in MS. Yet, the fundamentals of KIEs in collision‐induced dissociation (CID) in tandem mass spectrometry (MS/MS) are unclear, and information about chlorine KIEs (Cl‐KIEs) of organochlorines in MS is particularly scarce. This study investigated the Cl‐KIEs of dichloromethane, trichloroethylene, and tetrachloroethylene during CID using gas chromatography‐electron ionization triple‐quadrupole MS/MS. Cl‐KIEs were evaluated with MS signal intensities. All the organochlorines presented large inverse Cl‐KIEs (<1, the departures of Cl‐KIEs from 1 denote the magnitudes of Cl‐KIEs), showing the largest magnitudes of 0.797, 0.910, and 0.892 at the highest collision energy (60 eV) for dichloromethane, trichloroethylene, and tetrachloroethylene, respectively. For dichloromethane, both intra‐ion and inter‐ion Cl‐KIEs were studied, within the ranges of 0.820–1.020 and 0.797–1.016, respectively, showing both normal and inverse Cl‐KIEs depending on collision energies. The observed Cl‐KIEs generally declined from large normal to extremely large inverse values with increasing collision energies from 0 to 60 eV but were inferred to be independent of MS signal intensities. The Cl‐KIEs are dominated by critical energies at low internal energies of precursor ions, resulting in normal Cl‐KIEs; while at high internal energies, the Cl‐KIEs are controlled by rotational barriers (or looseness/tightness of transition states), which lead to isotope‐competitive reactions in dechlorination and thereby inverse Cl‐KIEs. It is concluded that the Cl‐KIEs may depend on critical energies, bond strengths, available internal energies, and transition state looseness/tightness. The findings of this study yield new insights into the fundamentals of Cl‐KIEs of organochlorines during CID and may be conducive to elucidating the underlying mechanisms of KIEs in collision‐induced and photo‐induced reactions in the actual world.     

溶剂气浮法去除水中腐殖酸的动力学和热力学初步研究

研究了溶剂气浮法去除水中的腐殖酸,该技术可以作为生物处理后的填埋渗出液的后处理方法。腐殖酸通过与表面活性剂十六烷基三甲基溴化铵生成离子缔合物气浮进入有机溶剂异戊醇而从水中去除。大于计量比的表面活性剂的量在10 m in之内可达92%的去除率。气浮速率在一定程序上随着气流速率的增加而增加,基本上与有机溶剂的体积无关。同时,还考察了电解质、乙醇及溶液的pH值对水中腐殖酸的溶剂气浮过程的影响。研究表明,该溶剂气浮过程遵从一级动力学。气浮过程的表观活化能作为一个特征参数被提出来,其值为2.87 kJ/mol。     

高效凝胶过滤色谱法分离测定豆薯种子蛋白

用高效凝胶蛋白往分离豆薯种子蛋白租提液,结合光电二极管阵列检测器对分离的蛋白峰进行紫外光谱扫描来确认蛋白的纯度,测定了3种蛋白的分子量,采用邻苯二甲醛（OPA）柱后衍生法测定了豆薯种子蛋白的氨基酸含量。