鱼体中有机毒物的气相色谱分析

在对第二松花江水中有机污染物进行深入探查(用GC-MS,GC-ECD,GC-FID配合方法)的基础上,为调查所探出有机毒物在该江鱼体中的残留量,建立了本法。实验表明,方法回收率平均超过80%,检测限分别为0.0001～0.015μg/g(ECD)和0.0092～0.14μg/g(FID)。本法测定“二松江”鱼,检出多种江水中存在的有机污染物。     

THERMODYNAMIC STUDY ON ADSORPTION OF AROMATIC SULFONIC ACIDS ONTO MACROPOROUS WEAK BASE ANION EXCHANGER FROM AQUEOUS SOLUTIONS

 The adsorption equilibrium isotherms of three aromatic sulfonic acid compounds, 2-naphthalenesulfonic acid, p-toluenesulfonic acid and p-chlorobenzenesulfonic acid, from aqueous solutions by macroporous weak base anion exchanger within the temperature range of 293 K-313 K were obtained. Several isotherm equations were correlated with the equilibrium data, and the experimental data was found to fit the three-parameter Redlich-Peterson equation best within the entire range of concentrations. The study showed that the hydrophobicity of solute has distinct influence on adsorption capacity of the anion exchanger for the aromatic sulfonic acid. Moreover, estimations of the isosteric enthalpy, free energy,and entropy change of adsorption were also reported. The positive isosteric enthalpy and entropy change for adsorption indicate an endothermic and entropy driven process in the present study.     

Stereoselective Synthesis of Piperamide Alkaloids by Modified Ramberg-Bcklund Reaction

A convenient and rapid approach for the synthesis of piperamide alkaloids la ~ h by the recently developed one-flask Ramberg-Backlund reaction was described. The synthesis of 1e was reported for the first time.     

苎麻叶中绿原酸的分光光度法测定

探讨了采用分光光度法测定苎麻叶中绿原酸的含量的方法。12.5%的醋酸用量为0.1mL,7%尿素2.0mL,0.5%亚硝酸钠0.25mL,3min后加入5%氢氧化钠0.5mL,绿原酸与试剂形成鲜红色络合物,通过在510nm处测定溶液的吸光度确定绿原酸的含量。绿原酸浓度在0.01~0.12g/L范围内与吸光度值有良好的线性关系,回收率为95%~107%,相对标准偏差(RSD)为2.4%。该方法简便、快速。     

A self-assembly/disassembly two-photo ratiometric fluorogenic probe for bacteria imaging

A fluorogenic probe for bacteria imaging was reported. The binding with anionic bacterial surfaces disassembled the self-assembly probe to turn-on the fluorescence and shift pyrene monomer/excimer ratiometric signals.     

Backbonding contributions to small molecule chemisorption in a metal–organic framework with open copper(i) centers

Metal–organic frameworks are promising materials for applications such as gas capture, separation, and storage, due to their ability to selectively adsorb small molecules. The metal–organic framework Cu^I-MFU-4l, which contains coordinatively unsaturated copper(i) centers, can engage in backbonding interactions with various small molecule guests, motivating the design of frameworks that engage in backbonding and other electronic interactions for highly efficient and selective adsorption. Here, we examine several gases expected to bind to the open copper(i) sites in Cu^I-MFU-4l via different electronic interactions, including σ-donation, π-backbonding, and formal electron transfer. We show that in situ Cu L-edge near edge X-ray absorption fine structure (NEXAFS) spectroscopy can elucidate π-backbonding by directly probing excitations to unoccupied backbonding orbitals with Cu d-character, even for gases that participate in other dominant interactions, such as ligand-to-metal σ-donation. First-principles calculations based on density functional theory and time-dependent density functional theory additionally reveal the backbonding molecular orbitals associated with these spectroscopic transitions. The energies of the transitions correlate with the energy levels of the isolated small molecule adsorbates, and the transition intensities are proportional to the binding energies of the guest molecules within Cu^I-MFU-4l. By elucidating the molecular and electronic structure origins of backbonding interactions between electron rich metal centers in metal–organic frameworks and small molecule guests, it is possible to develop guidelines for further molecular-level design of solid-state adsorbents for energy-efficient separations of relevance to industry.

In situ near edge X-ray absorption fine structure spectroscopy directly probes unoccupied states associated with backbonding interactions between the open metal site in a metal–organic framework and various small molecule guests.     

某些变色酸双偶氮染料-蛋白质体系的共振瑞利散射及其分析应用

在PH3．4－4．0的缓冲溶液中， 偶氮胂M（AAM）、偶氮氯膦Ⅲ（CPAⅢ）和氯磺酚S（CSPS）等变色酸双偶氮染料及蛋白质本身的共振瑞利散射（RRS）均十分微弱，但这些染料与蛋白质结合形成复合物时能使RRS急剧增强，在400－470nm的范围内呈现高的散射强度，其最大散射波大均位于470nm处，并且散射强度分别在0．36mg/L（CPAⅢ体系）、0－3．8mg/L(AAM体系）和0－4．8mg/L(CSPS体系）的范围内与牛血清白蛋白（BSA）的浓度成正比，方法具有高灵敏度，对于BSA的检出限（σ=3时）分别为18．5μg/L（CPAⅢ）、13．6μg/L（CSPS）和27．9μg/L（AAM）。考察了共存物质的影响，表明方法具有较好的选择性，此法可用于人血清中蛋白质的测定。     

鹿角短指软珊瑚Sinularia Cervicornis Tix-Dur 中的一个新糖甙-Cervicoside

珊瑚属腔肠动物门 ( Clelenterata) ,海鸡冠目 ( Alcyonacea) ,是一种热带与亚热带海洋中广泛分布Scheme 1　 Structure of cervicoside(1 )的低等海洋生物 .软珊瑚的次生代谢物中含有萜类和甾体类等各类生理活性物质[1～ 5] .我们在对鹿角短指软珊瑚的次生代谢产物研究中 ,分离到一个新三糖甙 ,命名为 Cervicoside( 1 ) ,结构见 Scheme 1 .该化合物具有较强的体外抗癌活性 .1　实验部分1 .1　样品　鹿角短指软珊瑚采自海南岛三亚海域 .样品储藏于中山大学化学与化学工程学院天然有机化学研究室 ,编号为 98- SY- 3.种属由中国科学院南海…     

Resonance Rayleigh scattering method for the recognition and determination of double-stranded DNA using amikacin

In weakly acidic buffer medium, the interaction of amikacin with calf thymus DNA, yeast RNA and denatured DNA has been investigated by using resonance Rayleigh scattering (RRS) technique. The result shows that calf thymus DNA is capable of enhancing the RRS intensity of the amikacin, while yeast RNA and denatured DNA have very little enhancement effect. Based on the characteristics, a sensitive assay for detecting double-stranded DNA in the presence of denatured DNA and yeast RNA has been developed. The enhancement of the RRS signal is directly proportional to the concentration of double-stranded DNA in the range 0.02-12.0 μg ml⁻¹ for calf thymus DNA and its detection limit (3σ) is 2.5 ng ml⁻¹. The method shows a wide linear range and high sensitivity, and almost no interference can be observed from RNA, denatured DNA, amino acid and most of the metal ions. The trace amounts of nucleic acid in synthetic samples and practical samples are determined with satisfactory results. Therefore, the proposed method is promising for as an effect means for recognition in vivo and determination in situ of double-stranded DNA.