宝兴大理石矿的放射性检测

宝兴县境内的大理石资源以其白度高、储量丰、品质优、易开采而享誉中外。对四川省宝兴县陇东镇大理石矿区进行了放射性环境地质调查,通过对取回的大理石样品中226Ra、232Th、40K这3种核素的比活度的测定,根据比活度换算出这几种核素的外照射指数和内照射指数,把所得结果和中华人民共和国国家标准《建筑材料放射性核素限量》中规定的建筑性材料分类标准作对比后发现其内照射指数与外照射指数都符合《建筑材料放射性核素限量》中A类建筑材料和装饰材料的要求,它的产销与适用范围不受限制。     

非线性物理破解神经编码机制

信息在神经系统中以脉冲点序列的形式传输和处理，神经系统如何通过脉冲点序列对所表达的信息进行编码，一直是一个谜．人们曾普遍认为，神经可能通过发放率（单位时间发放脉冲出现的次数）对信息编码，也有人猜测，神经可通过脉冲点序列的时序编码．由于神经发放的随机性，这就使得任何编码机制都面临着被表达信息的确定性与表达该信息的信号的随机性的矛盾．通过神经非线性随机动力学模型，文章作者发现，神经点序列的发放率对点序列的时序信息传输的影响，揭示了神经点序列时序信息在神经非线性传输中的随机共振特征．由此预期，并进一步通过听觉心理物理实验观察到，在一定条件下噪声对听觉的增强作用．从而通过非线性物理揭示了听觉时序编码机制的存在以及在时序编码中随机性噪声的积极作用．     

RP-HPLC and NMR study of antioxidant flavonoids in extract from <Emphasis Type="Italic">Gentiana piasezkii</Emphasis>

A reversed-phase high performance liquid chromatography (RP-HPLC) separation with photodiode array detection (PDA) was developed for the simultaneous determination of five flavonoids, lutonarin (LO), saponarin (SA), isoorient (IO), 7-O-feruloylorientin (FO) and luteolin (LE) in the extract of Gentiana piasezkii, a popular forage grass, pharmaceutical and ornamental plant in China. The optimized method was achieved for the separation and detection of selected constituents, using acetonitrile-1% acetic acid as the mobile phase with gradient elution at a flow rate of 0.8 mL/min and 350 nm as the detection wavelength. The contents of the five flavonoids, i.e., LO, SA, IO, FO and LE in the plant of G. piasezkii were 0.1524, 0.0673, 0.300, 0.0552 and 0.0052%, respectively. The compounds possess similar structures and have been studied by nuclear magnetic resonance (NMR) spectroscopy.     

赝标介子的唯象模型(Ⅱ)——电磁形状因子

本文直接以平底势计算得到的赝标介子波函数,在欧氏空间中计算出物理的0^-介子的类空电磁形状因子。数值结果表明,在适当选择参数下,理论计算的结果能和实验相符合。 关键词：     

Magnetic polyethyleneimine functionalized reduced graphene oxide as a novel magnetic solid-phase extraction adsorbent for the determination of polar acidic herbicides in rice

A novel magnetic polyethyleneimine modified reduced graphene oxide (Fe₃O₄@PEI-RGO) had been fabricated based on a self-assemble approach between positive charged magnetic polyethyleneimine (Fe₃O₄@PEI) and negative charged GO sheets via electrostatic interaction followed by chemical reduction of GO to RGO. The as-prepared Fe₃O₄@PEI-RGO was characterized by transmission electron microscopy (TEM), Fourier transform infrared spectrometry (FT-IR), X-ray diffraction (XRD), thermal gravimetric analyzer (TGA), vibrating sample magnetometer (VSM) and zeta potential analysis, and then was successfully applied to determine four phenoxy acid herbicides and dicamba in rice coupled with high performance liquid chromatography (HPLC). As a surface modifier of RGO, PEI not only effectually affected the surface property of RGO (e.g. zeta potential), but also changed the polarity of RGO and offered anion exchange groups to polar acidic herbicides, which would directly influence the type of adsorbed analytes. Compared with Fe₃O₄@PEI, Fe₃O₄/RGO and Fe₃O₄@PEI-GO, the as-prepared Fe₃O₄@PEI-RGO, integrating the superiority of PEI and RGO, showed higher extraction efficiency for polar acidic herbicides. Besides, the adsorption mechanism was investigated as well. It turned out that electrostatic interaction and π-π interaction were considered to be two major driving force for the adsorption process. Response surface methodology (RSM), a multivariate experimental design technique, was used to optimize experimental parameters affecting the extraction efficiency in detail. Under the optimal conditions, a satisfactory performance was obtained. The calibration curves were linear over the concentration ranging from 2 to 300 ng g⁻¹ with correlation coefficients (r) between 0.9985 and 0.9994. The limits of detection (LODs) were in the range of 0.67–2 ng g⁻¹. The recoveries ranged from 87.41% to 102.52% with relative standard deviations (RSDs) less than 8.94%. Taken together, the proposed method was an efficient pretreatment and enrichment procedure and could be successfully applied for selective extraction and determination of polar acidic herbicides in complex matrices.     

铜(Ⅱ)与2-吡啶酸、4,4′-联吡啶配合物的合成、结构和电化学性质(英文)

The complex [Cu(bipy)(pc)(H2O)(ClO4)]·H2O(1)(bipy:4,4'-bipyridine;Hpc:α-pyridine carboxylic acid) has been synthesized and characterized by single crystal X-ray diffraction method and elemental analysis.It crysrallizes in the Monoclinic space group P21/n.The crystal structure reveals that Cu(Ⅱ) centre adopts a pseudo octahedral geometry.Ligand 4,4'-bipyridine as a bridge coordinates to two different Cu(Ⅱ) center to form a onedimensional zigzag chain.One dimensional chains are linked by C-H…O hydrogen bonding interactions to form two-dimensional layer.Layers are connected by O…H-O hydrogen bond to generate three-dimensional structure.The cyclic voltametric behavior of complex 1 is also investigated.     

2-(5-甲基-1,3,4-噻二唑)-硫乙酸镍(Ⅱ)配合物的合成和晶体结构

本文合成了2个镍配合物[Ni(mtyaa)2(H2O)4]·4(H2O)(1)和[Ni(4,4′-bipy)2(mtyaa)2(H2O)2]·2H2O(2)(Hmtyaa=2-(5-甲基-1,3,4-噻二唑)-硫乙酸;4,4′-bipy=4,4′-联吡啶),用X-射线单晶衍射仪测定了配合物的单晶结构,并对它进行了元素分析、红外光谱、热重和粉末X-射线衍射等表征。配合物1和2的晶体分别属于三斜晶系和单斜晶系,空间群分别为P1和P21/n。X-射线单晶结构分析表明配合物1和2中镍原子均采取六配位扭曲的八面体配位模式。在配合物1中配位水和游离水分子与羧基氧之间的氢键作用将单分子结构连成三维网状结构。配合物2中配位水和游离水分子与羧基氧以及配体中的氮原子之间的氢键作用将链连接成二维层状结构。     

Determination of aristolochic acid in urine using hollow fiber liquid-phase microextraction combined with high-performance liquid chromatography

A simple and efficient hollow fiber liquid‐phase microextraction (HF‐LPME) technique in conjunction with high‐performance liquid chromatography is presented for extraction and quantitative determination of aristolochic acid I in human urine samples. Several parameters influencing the efficiency of HF‐LPME were investigated and optimized, including extraction solvent, stirring rate, extraction time, pH of donor phase and acceptor phase. Excellent sample clean‐up was observed and good linearity with coefficient of 0.9999 was obtained in the range of 15.4–960 µg/L. This method provided a 230‐fold enrichment factor and good repeatability with relative standard deviations (RSD) lower than 6.0%. The limit of detection value for the analyte in urine sample was 0.01 µg/L at a signal‐to‐noise ratio of 3. The extraction recovery from urine samples was 61.8% with an RSD of 9.71%. Copyright © 2010 John Wiley & Sons, Ltd.     

Simultaneous determination of seven alkaloids in Phellodendron chinense Schneid by high-performance liquid chromatography

By optimizing the extraction, separation, and analytical conditions, a reliable and accurate HPLC method coupled with a photodiode array detector was developed for simultaneous detection and quantification of seven alkaloids, i.e., (-)-(R)-platydesmin, noroxyhydrastinine, berberine, skimmianine, canthin-6-one, chilenine, and pteleine in "huangbo" (the bark of Phellodendron chinense), a commonly used herb in Traditional Chinese Medicine. The optimal condition for separation was achieved on a reversed-phase Cis column with a stepwise mobile phase gradient prepared from 0.1% phosphoric acid and acetonitrile. For all the alkaloids, a good linear regression relationship (r > 0.9997) was obtained between the peak area and concentration at the range of 0.5-700 microg/mL. The LODs and LOQs for the analytes ranged from 0.07 to 0.28 microg/mL and from 0.28 to 1.12 microg/mL, respectively. The optimized method was applied to the determination of alkaloids in several P. chinense samples, and found to be feasible and reliable. This method and quantitative results can provide scientific and technical bases for setting up QC standards to assure the safety and quality of P. chinense bark raw material, as well as for proprietary Chinese medicine products containing P. chinense bark.