LC–DAD–ESI-MS–MS Separation and Chemical Characterization of the Inflammatory Fraction of the Roots of Euphorbia kansui

In China the roots of Euphorbia kansui T.N. Liou ex T.P. Wang, known as ‘kansui’, have been used for centuries as a herbal remedy for edema, ascites, and asthma. Kansui, has inflammatory and tumor-promoting toxicity, and other side-effects, however, which have seriously restricted its clinical application. In the work discussed in this paper a simple and rapid LC–DAD–ESI-MS–MS method has been established for separation and characterization of the main compounds in the toxic fraction of E. kansui roots. Twelve diterpene derivatives were identified in the inflammatory fraction of kansui: kansuinine C, kansuinine B, kansuinine A, kansuinine D, 5-O-benzoyl-20-deoxyingenol, kansuinine E, kansuiphorin C, 3-O-benzoyl-20-deoxyingenol, 3-O-(2′E,4′Z-decadienoyl)-5-O-acetylingenol, 3-O-(2′E,4′Z-decadienoyl)-20-deoxyingenol, 20-O-(2′E, 4′E-decadienoyl)ingenol, and 3-O-(2′E,4′Z-decadienoyl)-20-O-acetylingenol. The inflammatory fraction was separated on a C₁₈ reversed-phase column with a mobile phase gradient. The proposed method is a scientific and technical platform enabling the herbal medicine industry to perform quality control and ensure the safety of preparations that contain this class of poisonous diterpenoids.     

Synthetic and structural studies of metal complexes derived from tris(3,5-bimethyl-pyrazolylmethyl)amine and pyridine derivatives

A series of metal complexes with a tripodal ligand, TMPzA, have been synthesized and characterized, and their single crystal structures have been determined by X-ray diffraction techniques. It has been found that when pyridyl derivatives as auxiliary ligands are added to the reaction mixture, the tripodal ligand TMPzA loses a pendant arm and coordinates with the metal centers to form the complexes: [Cu(DMPzA)(2,2′-bipy)]·(ClO₄)₂ (1), [(DMPzA)Cu(μ-4,4′-bipy)Cu(DMPzA)]·(ClO₄)₄ (2), [(TMPzA)Cu(μ-H₂DPC)Cu(DMPzA)]·(ClO₄)₂ (3), [(DMPzA)Co(μ-H₂DPC)Co(TMPzA)]·(ClO₄)₂ (4) [TMPzA = tris(3,5-bimethyl-pyrazolymethyl)amine; bipy = bipyridine; H₂DPC = pyridyl-2,6-bicarboxylate; DMPzA = bis(3,5-bimethyl-pyrazolmethyl)amine]. In order to investigate the effect of the pyridyl ring on the cleavage of the pendant arm in the tripodal ligand, a fifth complex, [(TMPzA)Co(μ-HZPC)Co(TMPzA)·(H₂O)₂]·(ClO₄)₃ (5), has been prepared by using pyrazole-carboxylate (HZPC) instead of pyridyl derivatives, and its crystal structure has been determined. It has been found that the pendant arm in TMPzA ligand has not been removed in complex 5. The results show that the complexes with TMPzA have a strong ability to recognize pyridine compounds in methanol solvent, and they have potential application for molecular devices in the future. The cleavage mechanism has been studied by DFT calculations and ESI-MS spectra.     

Side-chain conformational space analysis (SCSA): A multi conformation-based QSAR approach for modeling and prediction of protein–peptide binding affinities

In this article, the concept of multi conformation-based quantitative structure-activity relationship (MCB-QSAR) is proposed, and based upon that, we describe a new approach called the side-chain conformational space analysis (SCSA) to model and predict protein-peptide binding affinities. In SCSA, multi-conformations (rather than traditional single-conformation) have received much attention, and the statistical average information on multi-conformations of side chains is determined using self-consistent mean field theory based upon side chain rotamer library. Thereby, enthalpy contributions (including electrostatic, steric, hydrophobic interaction and hydrogen bond) and conformational entropy effects to the binding are investigated in terms of occurrence probability of residue rotamers. Then, SCSA was applied into the dataset of 419 HLA-A 0201 binding peptides, and nonbonding contributions of each position in peptide ligands are well determined. For the peptides, the hydrogen bond and electrostatic interactions of the two ends are essential to the binding specificity, van der Waals and hydrophobic interactions of all the positions ensure strong binding affinity, and the loss of conformational entropy at anchor positions partially counteracts other favorable nonbonding effects.     

串扰时延故障的SAT-ATPG算法研究

随着芯片运行速度不断提高,对串扰时延的测试已成为一个迫切需要解决的问题;文中提出一种面向多条攻击线的受害线上最大串扰噪声的测试生成方法;此方法建立了串扰通路时延故障模型、分析了布尔可满足性问题、讨论了七值逻辑,研究了串扰时延故障测试转换为CNF的逻辑表达式,在非鲁棒测试条件下约简CNF范式,并提出了串扰时延故障的SAT-ATPG算法;最后通过实例分析,对本文算法进行验证;结果表明:该算法对串扰时延故障的测试矢量的生成是有效的。     

基于LabVIEW的控制阀性能测试评估系统设计

控制阀在工业控制领域扮演十分重要的角色,但目前国内对控制阀性能测试评估系统的研究十分薄弱,常规的仪器仪表很难精确测试控制阀的性能。本文基于NI compactRIO硬件、各类传感器以及Labview软件开发设计了一套控制阀性能测试评估系统,该系统实现了控制阀的在线测试和功能评估,并且可将控制阀各项性能指标评估结果汇集于一张类似体检单的报表显示。采用该系统对某公司的直通气开式薄膜调节阀S9044进行了性能测试评估,实验结果表明,该系统能够精确地测试出调节阀的各项性能指标,且系统软件交互界面良好、扩展性强、精度高。     

触发电压对±100 kV多级多通道开关性能的影响

研制了一种用于快脉冲直线型脉冲变压器的±100 kV多级多通道火花开关,研究了触发电压极性、幅值对多级多通道火花开关触发性能的影响,分析了不同触发电压下开关各部分延时及抖动。研究结果表明:触发电压的极性对双极性多级多通道火花开关触发性能影响较小;开关的触发放电延时和抖动随着触发电压的增大而减小。进一步分析了多级多通道火花开关的触发击穿模式以及影响开关击穿延时和抖动的主要因素,提出了减小开关触发击穿延时及抖动的技术途径。     

Transition of Discharge Mode of a Local Hollow Cathode Discharge

The discharge characteristics of hollow cathode discharge in argon in a cylindrical cavity are investigated experi- mentally. The voltage-current （V - I） characteristics and the light emission are measured. It is found that the discharge plasma is localized inside the hollow cavity, with an extensive Faraday dark space between the cathode and the anode. The discharge develops from predischarge to abnormal glow discharge, the hollow cathode effect （HCE） and a hybrid mode as the discharge current increases. The onset of the HCE is found for the first time by the transition from abnormal glow discharge together with a significant decrease in the slope of the V - I curve which shows a positive differential resistivity. The voltage increases proportionally with the current when the HCE is reached.     

The exciton-longitudinal-optical-phonon coupling in InGaN/GaN single quantum wells with various cap layer thicknesses

This paper studies the exciton-longitudinal-optical-phonon coupling in InGaN/GaN single quantum wells with various cap layer thicknesses by low temperature photoluminescence (PL) measurements.With increasing cap layer thickness,the PL peak energy shifts to lower energy and the coupling strength between the exciton and longitudinal-optical (LO) phonon,described by Huang-Rhys factor,increases remarkably due to an enhancement of the internal electric field.With increasing excitation intensity,the zero-phonon peak shows a blueshift and the Huang-Rhys factor decreases.These results reveal that there is a large built-in electric field in the well layer and the exciton-LO-phonon coupling is strongly affected by the thickness of the cap layer.     

The transverse laser induced thermoelectric voltages in step flow growth （1-x）Pb(Mg1/3Nb2/3)O3-xPbTiO3 thin films

This paper reports that the transverse laser induced thermoelectric voltages (LITV) are observed for the first time in the step flow growth (1-x)Pb(Mg1/3Nb2/3)O3-xPbTiO3 (PMN-PT,x = 0.20, 0.33, 0.50) thin films deposited on vicinal-cut strontium titanate single crystal substrates. Because lead magnesium niobate-lead titanate is a solid solution of lead magnesium niobate (PMN) and lead titanate (PT), there are two types of signals. One is wide with a time response of a microsecond, and the other superimposed with the wide signal is narrow with a time response of a nanosecond. The transverse LITV signals depend on the ratio of PMN to PT drastically. Under the irradiation of 28-ns pulsed KrF excimer laser with the 248-nm wavelength,the largest induced voltage is observed in the 0.50Pb(Mg1/Nb2/3)O3-0.50PbTiO3 films. Moreover, the effects of film thickness, substrates, and tilt angles of substrates are also investigated.     

Synthesis of novel mesoporous carbon nanoparticles and their phytotoxicity to rice (Oryza sativa L.)

Despite the remarkable number of investigations on the potential risks of the engineered nanomaterials (ENMs) to terrestrial plants, there was limited knowledge regarding the effects of mesoporous carbon nanoparticles (MCNs) with different sizes on crops. The objective of our study was to evaluate the toxicity of MCNs to rice (Oryza sativa L.) seedlings. Two novel MCNs with different particle sizes (MCN1: 150 and MCN2: 80?nm) were synthesized using the high-temperature pyrolysis method and characterized by transmission electron microscopy (TEM), X-ray photoelectron spectroscopy, and Raman spectra. Phytotoxicity of two MCNs was then comparatively evaluated using rice as a model plant. The rice seedlings were hydroponically exposed to both MCN suspensions with concentrations of 0, 10, 50, 150?mg/L for 20?days. Exposure to 150?mg/L MCN1 resulted in more than 21% and 29% decrease in root length and in shoot length, respectively. MCN2 significantly reduced the root and shoot lengths by approximately 70% and 57% at the concentration of 150?mg/L. Additionally, the concentrations of three endogenous phytohormones, including brassinolide (BR), indole propionic acid (IPA), and dihydrozeatinriboside (DHZR) in plant shoots were increased significantly compared with the control. Our findings illustrated that size-effects of MCNs contributed greatly in causing phytotoxicity to plants, which should have drawn our attention to the use of these novel ENMs in agriculture given the evidence of their potential risks to crops. More importantly, this is the first study on assessment of the phytotoxicity of MCNs to rice seedlings from the perspective of plant hormones.