Qualitative and quantitative analysis of major constituents from Dazhu Hongjingtian capsule by UPLC/Q‐TOF‐MS/MS combined with UPLC/QQQ‐MS/MS

In this work, a sensitive and efficient method was established and validated for qualitative and quantitative analysis of major bioactive constituents in Dazhu Hongjingtian capsule by liquid chromatography tandem mass spectrometry. A total of 32 compounds were tentatively identified using ultra‐performance liquid chromatography coupled with quadrupole time‐of‐flight mass spectrometry. Furthermore, 12 constituents, namely gallic acid, 3,4‐dihydroxybenzoic acid, salidroside, p‐ coumaric acid‐4‐O ‐β ‐d ‐glucopyranoside, bergeninum, 4‐hydroxybenzoic acid, 4‐hydroxyphenylacetic acid, syringate, 6′′‐O ‐galloylsalidroside, rhodiosin, rhodionin and kaempferol‐7‐O ‐α ‐l ‐rhamnoside, were simultaneously quantified by the developed ultra‐performance liquid chromatography coupled with a triple quadrupole mass spectrometry method in 9 min. All of them were analyzed on an Agilent ZorBax SB‐C₁₈ column (3.0 × 100 mm, 1.8 μm) with linear gradient elution of methanol–0.1% formic acid water. The proposed method was applied to analyze three batches of samples with acceptable linearity (R , 0.9979–0.9997), precision (RSD, 1.3–4.7%), repeatability (RSD, 1.7–4.9%), stability (RSD, 2.2–4.9%) and recovery (RSD, 0.6–4.4%) of the 12 compounds. As a result, the analytical method possessing high throughput and sensitivity is suitable for the quality control of Dazhu Hongjingtian capsule.     

Metabolic characterization of the early stage of hepatic fibrosis in rat using GC‐TOF/MS and multivariate data analyses

The aim of this study was to explore the changes in the urine metabolic spectrum in rats with the early stage of liver fibrosis using gas chromatography–time of flight/mass spectrometry (GC‐TOF/MS), try to search for potential biomarkers and elucidate the probably metabonomic pathogenesis. The early stage of liver fibrosis was established with a single subcutaneous injection of carbon tetrachloride twice each week for 4 weeks continuously. At the end of the experiment, GC‐TOF/MS technology with multivariate statistical approaches such as principal component analysis, partial least squares‐discriminant analysis and orthogonal partial least squares‐discriminant analysis was used to analyze the changes in the metabolic spectrum trajectory and identify potential biomarkers. Twelve potential biomarkers in the model group, such as succinic acid, threonine and lactose, were selected, which indicate that the metabonomic pathogenesis of the early stage of liver fibrosis may be related to disorders of energy metabolism, amino acid metabolism and fatty acid metabolism.     

Metabolomics revealed the toxicity of cationic liposomes in HepG2 cells using UHPLC‐Q‐TOF/MS and multivariate data analysis

Cationic liposomes (CLs) are novel nonviral vectors widely used for delivering drugs or genes. However, applications of CLs are largely hampered by their cytotoxicity, partly because the potential mechanism underlying the cytotoxicity of CLs remains unclear. The aim of the present study was to explore the underlying mechanism of cytotoxicity induced by CLs on HepG2 cells. Differential metabolites were identified and quantified using ultra‐liquid chromatography quadrupole time‐of‐flight mass spectrometry (UHPLC‐Q‐TOF/MS). The toxicity of CLs on HepG2 cells was evaluated by multivariate data analysis and statistics. Additionally, CCK‐8 assay, heatmap, pathway and co‐expression network were carried out to explore the relations between the metabolites and the pathways. The results showed a dose‐dependent toxic effect of CLs on HepG2 cells, with an IC₅₀ value of 119.9 μg/mL. Multivariate statistical analysis identified 42 potential metabolites between CLs exposure and control groups. Pathway analysis showed significant changes in pathways involving amino acid metabolism, energy metabolism, lipid metabolism and oxidative stress in the CLs exposure group vs the control group. Metabolites related to the above‐mentioned pathways included phenylalanine, methionine, creatine, oxalacetic acid, glutathione, oxidized glutathione, choline phosphate and several unsaturated fatty acids, indicating that cells were disturbed in amino acid metabolism, energy and lipid supply when CLs exposure‐induced injury occurred. It is concluded that CLs may induce cytotoxicity by enhancing reactive oxygen species in vitro , affect the normal process of energy metabolism, disturb several vital signaling pathways and finally induce cell death.     

一种测量磁光阱中冷原子密度和温度的新方法

报道了对磁光阱中冷铯原子吸收谱的实验观察,由于冷原子的多普勒增宽远小于激光发态超精细分裂,实验观察到三个孤立的吸收峰（Cs,6S1/2,F=4→6P3／2,F＝3,4,5,）其吸收系数比为3：7：12,这与相应跃迁振子强度一致。利用吸收信号测量了冷原子云的密度.结果与荧光探测法在10％的精度内符合;用吸收信号测量了冷原子的温度,测量结果与用荧光飞行时间法和释放捕捉法的结果吻合。     

基于飞行时间技术的PET发展历史与现状

简要介绍了基于飞行时间（Time of Flight, 简称TOF）技术的正电子发射断层扫描成像（Positron Emission Tomography, 简称PET）的基本原理, 回顾了TOF-PET成像设备的发展历史, 讨论了影响TOF PET时间分辨率的主要因素, 并对TOF-PET给图像重建技术带来的挑战进行了分析。 最后, 重点介绍了TOF-PET技术所带来的优势, 使用TOF技术可以有效地改善图像质量, 并且为临床诊断和临床前研究带来便利。 The principle of time of flight (TOF) positron emission tomography (PET) and a brief review of the history of TOF-PET are introduced. The factors influencing the time resolution of a TOF-PET scanner are presented, especially focus on the intrinsic properties of scintillators and front end electronics. Challenges and achievements of the structure of data organization and image reconstruction are reviewed. Finally, the benefits of TOF-PET on image quality improvement and tumor detection are emphasized.     

Design and test of a Multi-gap Resistive Plate Chamber with Long readout-strip （LMRPC）

A new kind （two end readout） of Multi-gap Resistive Plate Chamber with long readout-strip （LMRPC） is developed to be used at the large-area Muon Telescope Detector （MTD） at mid-rapidity at RHIC/STAR experiment for Time-of-Flight （TOF） measurement. The LMRPC has an active area of 87 cm× 17 cm, 10 gas gaps of 250 μm arranged in 2 stacks, with readout strips of 2.5 cm wide and 90 cm long. The considerations in LMRPC design related to its performance are discussed in this paper. The cosmic ray test results of a prototype LMRPC show a detection efficiency 〉95% and the time resolution -70 ps.     

双层飞行时间探测器(TOF)的性能研究

利用BC408塑料闪烁体直接耦合R2490–05高抗磁光电倍增管,组成双层飞行时间探测器.通过2GeV的π–束流测量,结果表明其本征时间分辨(标准偏差)≤50ps.利用该探测单元组成的飞行时间探测器系统,以其时间性能、结构、技术成熟和价格的优势,可以应用到τ–c工厂的带电粒子鉴别系统上.     

Structure and stability of (A1N)n clusters

AIN and AI₂N₂ have been observed in the record of time-of-flight mass-spectra as positive ions. Associating with density functional theory(DFT) B3LYP method with 6-31G* basis set, we have carried out the optimizing calculations of the geometry, electronic state and vibrational frequency for (AIN)_n (n = 1—15) clusters, moreover, discussed the character of the chemical bond and thermodynamical stability and explained the experimental mass spectra. The results show that there do not exist AI-AI and N-N bonds and only exists Al-N bond in the ground state structures of (AIN)_n clusters; and the “magical number” regularity of (AIN)_n is those whose atom number is 4, 8, 12, 16, 20, etc, all of which are times of four.     

Influence of basic residues on dissociation kinetics and dynamics of singly protonated peptides: time‐resolved photodissociation study

Product ion yields in postsource decay and time‐resolved photodissociation at 193 and 266 nm were measured for some peptide ions with lysine ([KF₆ + H]⁺, [F₆K + H]⁺, and [F₃KF₃ + H]⁺) formed by matrix‐assisted laser desorption ionization. The critical energy (E₀) and entropy (ΔS^?) were determined by RRKM fitting of the data. The results were similar to those found previously for peptide ions with histidine. To summarize, the presence of a basic residue, histidine or lysine, inside a peptide ion retarded its dissociation by lowering ΔS^?. On the basis of highly negative ΔS^?, presence of intramolecular interaction involving a basic group in the transition structure was proposed. Copyright © 2009 John Wiley & Sons, Ltd.     

Structure of Cyclic Aryl Thioester Dimer Based on o-Phthaloyl Dichloride and Bis(4-mercaptophenyl) Sulfide

IntroductionTheadvantageofmacrocyclicoligomersasprecursorsforthepreparationofhighperformancepolymersviaring openingpolymerization (ROP)hassparkedmuchinterestintheareaofadvancedthermoplasticcomposites.1 3Andaseriesofcyclicoligomerssuchascarbonates,4 arylesters ,5,6 ethers,7amides8andsulfides9,10 hasbeensuccessfullysynthesized .Recently ,Nishikuboetal.11reportedakindofnovelmacro cyclicoligomerscontainingthioestergroupspreparedbycon densationofbis(4 mercaptophenyl)sulfidewitharomaticaciddichlo…