Analytical strategies to determine antibiotic residues in fish

The accelerated growth of aquaculture has resulted in a series of harmful effects to human health. The widespread and unrestricted use of antibiotics in this industry, to prevent bacterial infections, leads to remaining amounts in the aquatic environment. This has resulted in the emergence of antibiotic-resistant bacteria in aquaculture environments, in the increase in antibiotic resistance in fish pathogens as well as in the transfer of these resistance determinants to human pathogens. Moreover, the use of large amounts of antibiotics may lead to the presence of residual antibiotics in fish tissue and fish products. Fluoroquinolones, tetracyclines, penicillins, sulphonamides and other antibiotics, exhibiting activity against both Gram-positive and Gram-negative bacteria, are widely used for the treatment and prevention of diseases in fish. An extended and comprehensive review on the recent analytical methodologies concerning antibiotic residues in fish reported in the literature is provided in the present article. Emphasis is given on sample preparation regarding isolation and purification, chromatographic conditions and method validation according to legislation. Results of published assays are comparatively presented and criticised.     

化学体系随机共振现象的理论研究

化学体系中随机共振现象的特性、机理、本质和应用的研究是非常重要的前沿课题。综述中国科学技术大学非线性化学实验室,在化学体系随机共振现象的理论研究中,所取得的主要成果,并阐述化学体系随机共振现象研究中所提出来的若干重要问题：非均相化学体系中随机共振;化学体系中内信号随机共振;化学体系中多重随机共振;化学体系中随机共振的调制;化学体系中色噪声作用下的随机共振;化学体系中时空随机共振;耦合化学体系中随机共振;化学体系中双参量随机共振。     

延边地区65～108岁健康老人头发中锌、铜、铁、锰、镁的含量

用原子吸收光谱法测定延边地区317名65～108岁老人头发中锌、铜、铁、锰、镁含量，观察不同民族、性别、年龄老人这些元素的差异。结果表明：1.朝鲜旗发锌低于汉族，满族发铜低于汉族、朝鲜族，汉族发镁高于朝鲜族、满族，发铁、发锰在汉、朝、满民族之间无区别。2．汉族、朝鲜族男发锌高于女性，汉族女性发铜高于男性，发铁、发锰、发镁在性别之间无区别。3、90岁组朝鲜族发锰、发镁低于65岁、76岁组，朝鲜族发锌、发铜、发铁在65～108岁之间无统计学意义。     

Alteration in photosystem II photochemistry of thylakoids isolated from senescing leaves of wheat seedlings

Wheat seedlings, grown for 7 days in the light, were allowed to senesce in the light or dark, and the change in the photosystem II (PS II) photochemistry of chloroplasts isolated from the primary leaves of these seedlings was investigated. The decrease in oxygen evolution and the fast fluorescence results indicated that the impairment of PS II in the leaves of seedlings senescing in the light was different from that in the leaves of seedlings senescing in the dark. Thermoluminescence studies showed a structural modification in the Q_B protein of chloroplasts isolated from leaves senescing in the light and an alteration in the S state transition of chloroplasts isolated from leaves senescing in the dark.     

ESR方法检测竹红菌素的半醌负离子自由基

从顺磁共振波谱检测到通过竹红菌素的光诱导还原和基态竹红菌素跟脂肪胺的电子转移两条途径所得到的自由基信号, 并由电化学还原得到同一自由基, 确认它为半醌负离子自由基。竹红菌素溶液中加入芳香胺观察不到ESR信号。它的3,10位上与醌基相邻近的羟基离解以后, 无论在基态还是在激发态都观察不到ESR信号。此外, 还从吸收光谱观察到半醌负离子自由基吸收以及竹红菌素跟脂肪胺之间的相互作用。     

壳聚糖及其在分析化学中的应用

综述了壳聚糖、甲壳素在污水处理、电化学、原子吸收光谱、高效液相色谱、吸光光度法中的应用。引用文献28篇。     

The Behavior of Trivalent and Pentavalent Methylarsenicals in Lake Biwa

Seasonal changes in the distribution of arsenic species were observed in a dredged area in the southern basin of Lake Biwa, Japan. The concentrations of dimethylarsenic acid [DMAA(V)] became comparable with those of inorganic forms during a stratification period. DMAA(V) increased not only in the photic zone but also in the hypolimnion. In the photic zone, an increase in DMAA(V) was observed with the yearly maximum of water temperature. In the hypolimnion, the seasonal changes in methylarsenicals differed from those in surface waters. DMAA(V) maxima appeared seasonally under sub-anoxic conditions and developed regionally at the redox boundary and above the sediment surface. The DMAA(V) concentrations increased in the initial period of oxygen depletion and just after the disappearance of anoxia, while they diminished in the anoxic hypolimnion by midsummer. The seasonal behavior of trivalent methylarsenicals, which are readily oxidized in oxic environments, was similar to that of DMAA(V). The total arsenic concentration in the surface layer rose to a maximum in late summer. Methylarsenicals did not increase in such a way that the total arsenic concentration increased during summer. © 1997 by John Wiley & Sons, Ltd.     

Evaluation of the Fate of Aldicarb and Its Metabolites in Oranges

Abstract

The accumulation, persistence and fate of systemic pesticide aldicarb was melencholy evaluated in orange crops. The concentration of this pesticide and its two toxic metabolites, aldicarb sulfoxide and aldicarb sulfone was determined in leaves, rind and pulp of three orange varieties (Satsuma, Navelina and Clemetina de Nules) and in the top soil of the orange groves. The groves were located in two different places in the Valencia Community (Spain). The analysis showed that the aldicarb concentration was lower than those of aldicarb sulfoxide and aldicarb sulfone. In all cases, the residues persisted at least 160 days in vegetable samples and between 157 and 227 days in soil samples. Residue concentrations measured in the soil samples were highly variable but a relation with the organic matter content can be observed. The residue levels found in vegetal products were higher in leaves than in rind, and in rind than in pulp. The maximum residue values were obtained between 47 and 70 days after the application. One hundred days after treatment (Security period) the residue levels of total fruit were lower than the maximum residue level of 0.2 mg/kg established by law.     

Evaluation of hydrogen ion concentrations in prostates from rats and dogs using fluorescent confocal microscopy

The knowledge of intracellular spatial distribution of pH in prostates in animal models reflective of human prostate may have implications for drug development upon pH dependent drug delivery and activity. Freshly dissected prostate tissues (in vitro) or the entire prostate gland (in vivo) were loaded with fluorescent dyes and viewed using confocal microscopy. Images were initially taken in tissues perfused with RPMI-1640 medium. Calibration in situ was performed with high potassium buffers of known pH containing nigericin. Acetoxymethyl ester carboxy-SNARF-1 was visible in epithelial cells (but not stroma) in rat and dog prostates. The pH of lysosomes in prostate epithelial cells was 5.2 as determined by fluorescence of Lyso Sensor Green DND-189. A method of in situ confirmation of tissue viability was developed by a secondary loading and visualization of the BCECF fluorescent dye. Besides the direct measurement of the pH in rat and dog tissues (pH ≈ 7.0), a method of pH measurement in prostate tissue (rather than in cell culture) was developed.     

Calibration methods for microdialysis sampling in vivo: muscle and adipose tissue

Calibration methods for microdialysis sampling were studied in the muscle and adipose tissue of rats. Both the delivery method and the no-net-flux method were used to determine the extraction efficiency (EE) of acetaminophen and caffeine in both tissues. There was no concentration dependence of the EE either in vitro or in vivo for either acetaminophen or caffeine. The EEs determined by the delivery and no-net-flux methods were not different. However, the EEs of both caffeine and acetaminophen determined in vitro were significantly higher than those determined in the muscle and adipose. This indicates that mass transfer in the tissue is the rate-determining factor for the EE in vivo. The relative difference between the EE in vitro and the EE in the muscle was smaller than the difference between the EE in vitro and the EE in the adipose. In addition, the EE in the muscle decreased more than the EE in the adipose after the animal was euthanized. This indicated that exchange between the extracellular fluid and plasma is the rate-determining step in mass transport relative to microdialysis sampling. This has a more significant effect on the EE in the muscle than the EE in the adipose. Both the delivery and no-net-flux methods can be used to calibrate microdialysis probes in the muscle and adipose.     

Enhanced Electronic Conjugation in Anthracene-Linked Porphyrins

Despite their larger separation , the porphyrin groups in 1 are more strongly conjugated than in analogous compounds in which butadiyne is the bridging unit. This stronger electronic coupling in 1 results in a bathochromic shift in its absorption and emission spectra.     

汉中青少年头发5种元素的分析

用原子吸收光谱法测定了陕西汉中地区２６６例健康男女青少年头发中５种金属元素的含量。并进行了直线相关回分析。结果表明,青春期女性头发中的铜,锌、铁、钙,镁５种元素的含量皆明显高于同年龄段男性;Ｃａ与Ｍｇ、Ｚｎ、Ｆｅ元素含量之间有不同程度的相关。     

生化分析用荧光纳米粒子研究进展

荧光纳米粒子在生化分析领域的应用研究近十年来取得了令人瞩目的进展,引起了研究者的广泛关注,如何制备强荧光发光、高生物亲和的荧光纳米粒子是其在生化分析领域应用的前提和基础。本文评述了近年来在生化分析领域应用较多的几种荧光纳米粒子的研究进展与状况。引用文献103篇。     

金乌贼脑和视神经节蛋白质组比较分析

采用双向凝胶电泳(2D-PAGE)技术优化分离金乌贼的脑及视神经节全蛋白质, 并选用肽质量指纹谱(Peptide mass fingerprinting, PMF)技术和数据库检索方法对2D-PAGE图谱上的部分蛋白质斑点进行鉴定, 初步构建了金乌贼视神经节(Optic ganglion of Sepia esculenta, SEOG)和脑神经节(Cerebral ganglion of Sepia esculenta, SECG)部分分子解剖图谱. 用Melanie 4 Trial软件分析脑神经节和视神经节蛋白质斑点总数量分别为682和594个, 其中SECG蛋白质斑点数量明显多于SEOG. 在脑神经节和视神经节中均发现了线粒体苹果酸脱氢酶前体(Mitochondrial malate dehydrogenase precursor, pre-MDH)及可溶性NSF连接蛋白(SNAP-type proteins). 此外, 延长因子(Elongation factor G)、微管蛋白(Tubulin)和肌动蛋白(Actin)等蛋白质也具有高匹配率. 已鉴定的蛋白质, 多数归属于假定蛋白和结构蛋白类.     

氨基苯磺酸和氨基萘磺酸在反相离子对色谱和离子色谱中分离行为的比较

本文考察了氨基苯磺酸和氨基萘磺酸染料中间体在反相离子对色谱和离子色谱中的分离行为，结果表明一些异构体在反相色谱中的保留顺序与离子色谱中的顺序发生颠倒。静电作用力在离子色谱中对保留值的贡献比在反相离子对色谱中对保留值的贡献要大，而疏水作用力在反相离子对色谱中对保留值的贡献却较在离子色谱中对保留值的贡献要大。离子对色谱更有利于有机离子的分离分析。     

Phosphaalkynes—Syntheses,Reactions, Coordination Behavior [New Synthetic Methods (73)]

Organophosphorus compounds have been applied in two ways in chemical synthesis. They can either be used as a reagent in a step of the synthesis (for example, in the Wittig reaction) or they can be incorporated directly into the target molecule. This second application, in particular, has expanded greatly in the last few years with the preparation of low-coordination phosphorus compounds. These include the phosphaalkynes, which are of great interest to organic and inorganic chemists. Phosphaalkynes have been employed in the synthesis of heterocyclic compounds, phosphaarenes and their valence isomers, and polycyclic compounds. Further applications have been the use of phosphaalkynes as new ligand systems in complex chemistry and their cyclooligomerization with organometallic reagents. While the chemical properties of phosphaalkynes have little in common with those of nitriles, they are in many ways very similar to those of the isoelectronic acetylenes.     

汽油铅与血铅的关系

论述了汽油铅对人体血铅水平的影响，主要内容包括：血铅水平与大气铅水平的关系，大气铅水平与加铅汽油耗量的关系，汽油铅耗量与居民血铅水平的关系。     

Trends in the development of nucleic acid biosensors for medical diagnostics

Some of the recent advances in the field of biosensors for nucleic acid analysis in medical diagnostic applications are highlighted. Particular attention is paid in this review to the progress made in two key areas of development: (i) enhancements achieved in device selectivity, and (ii) enhancements achieved in device sensitivity.     

The transport properties of polyimide isomers containing hexafluoroisopropylidene in the diamine residue

The effect of modification of the central moiety of the dianhydride residue and isomerism on the gas transport and physical properties were compared for six polyimides containing the hexafluoroisopropylidene group in the diamine residue. Substitution of bulkier groups within the dianhydride residue resulted in disruption of chain packing and slight increases in resistance to chain motions which led to an increase in permeability with little loss in selectivity. The permeabilities and diffusivities in the meta connected polyimide isomers were considerably lower than in the para connected polyimide isomers. Similarly, the permselectivities in the meta connected isomers were consistently higher than in the para connected isomers. These lower permeabilities and higher permselectivities were a result of the more dense packing and a significant suppression of small scale motions in the meta connected isomers. The suppression of segmental mobility in the meta connected isomers was indicated by an increase in the sub Tg transition temperatures in these materials relative to the para connected isomers. The differences in transport properties for these polyimides were attributed to contributions by several factors, including: (1) total free volume (2) distribution of free volume (3) intersegmental resistance to chain motions, and (4) intrasegmental resistance to chain motions. © 1994 John Wiley & Sons, Inc.     

The transformation of ferrihydrite in the presence of trace Fe(II): The effect of the anionic media

The transformation from ferrihydrite to various iron oxides and iron oxyhydroxides has been given much attention not only in environmental science and geochemistry but also in biology and material science. This laboratory study attempted to investigate Fe(II)-induced transformation of ferrihydrite in sulfate-rich medium. The results indicate that the transformation in sulfate-rich medium differs from that in Cl⁻ medium in the species, the amount and the morphology of products and transformation rate. Lepidocrocite is a main ingredient in the product in Cl⁻ medium at room temperature (RT), while goethite is the only product in SO₄²⁻ medium at RT. Goethite particles obtained in Cl⁻ medium are star-like but rod-like in SO₄²⁻ medium. The transformation rate in the latter medium is obviously slower than that in the former medium. The formation of lepidocrocite depends on both the ionic strength of the system and the dissolution rate of ferrihydrite.