Effect of the displacement reaction on the composition of the magnetic layer in electrodeposited layered nanostructures Co-Cu/Cu and Ni-Cu/Cu

Methods of stripping voltammetry, quartz microgravimetry, and x-ray-fluorescence analysis are employed to explore the copper displacement process on thin electrodeposited layers of pure cobalt and nickel and on deposits of these metals with inclusions of copper. The displacement reaction proceeds at a considerable rate on cobalt in the sulfate and sulfosalicylate solutions and virtually does not proceed on nickel in both the sulfate or sulfate-chloride solutions. An estimate of the rate of the copper displacement reaction following a change in the concentration of copper ions in the solution and in the pH of the sulfosalicylate solution is given. A decrease in the contact exchange rate is facilitated by a decrease in the concentration of copper ions in solution and their participation in the formation of complexes.     

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。     

青藏高原湖泊影响锂元素迁移和富集的矿物、元素及环境因素——以西藏郭扎错钻孔沉积物为例

作为我国战略性矿产的锂矿,主要赋存于青藏高原盐湖中。湖泊系统中,锂的富集和迁移规律关系到锂矿的高效提取和未来锂矿的储量估算。本文以西藏咸水湖郭扎错的钻孔沉积物为例,结合AMS14C年代和Mg元素含量变化,系统分析了孔隙水、碳酸盐矿物和硅酸盐矿物的锂含量变化,探讨了矿物、镁元素、环境变化和早期成岩作用等对锂元素迁移和富集的影响。郭扎错沉积物中锂和镁大部分存在于硅酸盐矿物中,锂和镁较高的相关性说明二者存在于相同的硅酸盐矿物中,如粘土矿物。大约90%的锂赋存在硅酸盐矿物中,约8.5%的锂赋存在碳酸盐矿物中,孔隙水中的锂含量占比仅约1.5%。碳酸盐矿物中Mg/Li摩尔比值为78–270,是孔隙水中10多倍,而硅酸盐矿物中的Mg/Li摩尔比值稳定在24–29之间。水–沉积物相互作用促进硅酸盐矿物中锂的释放,咸水环境下释放的锂多于淡水环境下。碳酸盐矿物中,锂和镁主要存在于方解石中。镁离子对锂离子的迁移具有阻碍作用,低温、高盐度下的阻碍作用更强。湖泊沉积物可能是湖水锂的一个重要来源。     

The conductance of bile salt-lecithin-water mixtures

The conductance of aqueous solutions of sodium glycodeoxycholate and sodium taurodeoxycholate displays a complex concentration dependence (0–0.5 C) with a maximum and minimum occurring in dilute solutions. This behavior can be related to physiologic concentrations observed in hepatic and gallbladder bile and interpreted in terms of anion dimerization and ultimately micellization. The addition of lecithin in 1:2 or 1:5 molar ratios results in micellization at lower concentration, disappearance of the maximum and minimum in the conductance curve, and a decrease in the total conductance.     

Effects of dilute acid and steam explosion pretreatments on the cellulose structure and kinetics of cellulosic fraction hydrolysis by dilute acids in lignocellulosic materials

Worldwide, yellows diseases impact plants important in human nutrition, the natural environment, and the culture and commerce of humans. Since the presumed pathogens, mycoplasma-like organisms (MLOs), have not been isolated in pure culture in vitro, their study must proceed by other experimental approaches. In a study of disease affecting grapevines in Europe and North America, polymerase chain reactions (PCR) and restriction analyses of PCR-amplified DNA were used to detect and differentiate strains of MLOs associated with grapevine yellows. MLOs were detected both in naturally diseased grapevines and in experimentally inoculated host plants. The data indicated an unexpected genomic diversity among grapevine-infecting MLOs, and supported their classification with MLOs in the aster yellows, X-disease, and elm yellows groups. The presence of diverse MLOs in grapevines provokes consideration that these MLOs may be present in overlapping geographic ranges and that multiple MLO infections may occur in individual plants, increasing the complexity of grapevine yellows epidemiology and control and the significance of sensitive MLO detection in planting stock and phytosanitary-regulated germplasm.     

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.     

Butyltin compounds in severn sound,lake huron,canada

Severn Sound is a heavily used recreational and beating area in the southeast corner of Georgian Bay, Lake Huron, Canada. Because of the concern over the possible release of tributyltin species (TBT) from antifouling paints on boat hulls and marinas, surveys were carried out in 1989 and 1992 to determine the presence of this species and its degradation products dibutyltin (DBT) and monobutyltin (MBT) in this area. Many fish (pike and young–of–the–year spottail shiners) and sediment samples collected in 1989 contained detectable levels of TBT. A maximum concentration of TBT was recorded in northern pike in the spring to be 240 ng Sn g^?1. Maximum levels occurred in marinas during the beginning of the boating season and significantly reduced during the summer and early autumn, although the maximum value of TBT in sediment (392 ng Sn g^?1) was observed in the summer of 1989. The seasonal variation of TBT levels was further substantiated in the subsequent 1992 study, in which sediments from three areas in a marina were sampled at monthly intervals from May to October. TBT levels were much higher in May and then generally decreased with time. Mussels (Elliptio complanta) caged in the marina for three months also contained TBT. DBT was frequently detected in the sediments but less frequently in fish and mussels. MBT was generally below detection limits. Plants (macrophytes and cladophora) contained very small amounts of butyltin compounds.     

Fate and occurrence of X-ray contrast media in the environment

Interest in the presence of pharmaceuticals in the environment has recently increased. Despite continuous research efforts there is still a large gap in our knowledge of their fate and effects on the ecosystem. This review covers current information on the occurrence of iodinated X-ray contrast media (ICM) in the environment and developments in the analysis of these highly polar organic micropollutants in aqueous environmental samples. Findings from monitoring surveys conducted on wastewater-treatment plants (WWTP), surface waters, and drinking waters are compiled, and strategies for removal of the compounds in WWTP and waterworks using advanced treatment are reported. Characteristics and advantages of different compound-specific or element-specific mass spectrometric techniques used to monitor ICM in the environment are compared, and applications in elucidation of the structures of biotransformation products, generated in laboratory-scale experiments that simulate sewage treatment or river water/sediment systems, are described.     

Matrix-assisted laser desorption/ionization mass spectrometry for the characterization of ionic liquids and the analysis of amino acids, peptides and proteins in ionic liquids

Ionic liquids are interesting solvents for a number of applications in chemistry and biotechnology. We characterized five different ionic liquids by laser desorption/ionization (LDI) and by matrix-assisted laser desorption/ionization (MALDI) mass spectrometry (MS) and studied the analysis of amino acids, peptides and proteins dissolved in these solvents. Signals of both anions and cations of the ionic liquids could be observed both in LDI- and in MALDI-MS. In the latter case, adduct formation between anions and cations of the analytes was observed. Amino acids, peptides and proteins could be analyzed in ionic liquids after addition of matrix substances. Sodium and potassium adducts were not observed in any analysis involving ionic liquids. Low molecular mass compounds and peptides could be analyzed best in the presence of water-immiscible ionic liquids, whereas proteins gave the best results in water-miscible ionic liquids. Optimal analysis conditions such as molar matrix-to-analyte and ionic liquid-to-matrix ratios were determined. Homogeneity of samples in the presence of ionic liquids was reduced compared with classical MALDI preparations. Relative quantitation of amino acids was possible using isotope-labeled internal standards. MALDI-MS thus can be used for the analysis of chemical reactions and the screening of enzyme-catalyzed reactions in ionic liquids and for the analysis of the biocatalysts dissolved in these solvents. Theoretical aspects of ion formation in the presence of ionic liquids both in LDI and MALDI analysis are discussed.     

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。     

谈科学探究中的归纳与演绎

逻辑推理过程与事物的认识过程同时存在,科学探究离不开逻辑推理过程。归纳和演绎是认识过程中的两种逻辑推理形式,在学生的科学探究活动中,尤其是在提出问题、猜想与假设、设计实验方案与解释结论阶段,归纳和演绎发挥着重要的作用。本文重点论述了寻求现象原因的求异归纳推理、探寻化学物质通性及变化规律的不完全归纳推理、探求个别物质性质的演绎三段论、解释个别现象的演绎解释推理过程在科学探究中的重要作用。     

Therapeutic use of hyaluronan

Hyaluronan used today as a therapeutic agent in human and animal medicine must be in a highly purified form, free of immunologically active protein molecules, from endotoxin and from inflammatory molecules originating from the tissues or bacterial cultures—the source of hyaluronan. All hyaluronans, whether in liquid or in covalently crosslinked gel form, must have certain elastoviscous properties to be usable for current therapeutic applications. Elastoviscous properties are especially important in the ophthalmic viscosurgical use. The metabolism of hyaluronan is very fast in most tissues, except in the vitreus. The ability of injected hyaluronan with a short half-life time in the joint to accomplish long-lasting analgesia represents a challenge for the design of the various products. The history of the therapeutic use of hyaluronan and its present status is described, with emphasis on its use in ophthalmic surgery and for a long-lasting analgesia in arthritic joints in humans and animals. The use of hyaluronan gels is described in viscoaugmentation as injected into the dermal layer of the skin. Hyaluronan gels were also used as viscosupplements injected into sphincter muscles to improve their function in aging or disease. The use of hyaluronan and its gel for drug delivery was suggested several decades ago, and is also mentioned.     

石柱黄连及根际土壤中矿质元素特征分析

研究石柱黄连不同器官及其根际土壤中矿质元素特征,探究黄连根茎矿质元素间及其与土壤环境的相关性。采用电感耦合等离子体质谱法(ICP-MS)、电感耦合等离子体发射光谱法(ICP-OES)及原子荧光光谱法(AFS)测定了15组石柱黄连植株和根际土壤中18种矿质元素含量,所得数据运用SPSS 22.0统计软件分析。石柱黄连根际土壤中锰、磷、镁、镉、汞等元素含量的变异性较大,部分采样点土壤中镉含量超过农用地土壤污染风险筛选值。在检测的18种元素中,黄连植株中钙、镁、磷、钾含量最高,其次是铁、锰、锌,再次是锶、铜、镍,最后是铅、钒、钴、镉、钼、铬、砷、汞。须根对大部分矿质元素的富集能力强于根茎或地上部;黄连根茎对锌的富集能力强于须根或地上部;地上部对钙、磷、钾、铬的富集能力强于须根或根茎。Spearman分析表明黄连根茎矿质元素间、黄连根茎与土壤中矿质元素有一定相关性,部分具有统计学意义(P＜0.05)。石柱黄连不同器官中矿质元素含量有明显差异,以此建立的指纹图谱可用于区分黄连根茎及须根的粉末样品;黄连根茎中矿质元素间主要表现为协同作用,黄连根茎与土壤中矿质元素既有协同作用又有拮抗作用。     

Complex dynamics of multicomponent biological coacervates

Phase transitions and coacervates play key roles in natural and synthetic soft matter. In particular, the past few years have seen a rapid expansion in studies of these phenomena in the context of dynamic cellular compartmentalization. In this brief review, we mainly focus on a few concepts and selected in vitro and cellular examples of recent developments in the areas of dynamics and multicomponent systems. Topics covered include the flexibility and conformational dynamics of polymeric species involved in phase separation, valence and non-monotonic effects, noise modulation and feedback loops, and multicomponent systems and substructure. The fundamental concepts discussed in this review are widely applicable, including in the context of cellular function and the development of materials with novel properties.     

Electrophoretic studies for determining soy proteins–xanthan gum interactions in foams

The aim of this work was to elucidate soy proteins–xanthan gum interactions at a molecular level by studying protein composition at the air–water interface of foams and in the solutions used to make them and to see if the different properties of heat denatured protein were reflected in the proportions in which they were present at the interface or in the ability to interact with xanthan. To this end SDS-PAGE and densitometry was employed. Initial protein concentration and xanthan influenced the composition of proteins in the solutions used to make the foams. The increase in NSP concentration of solutions (0.5–6 wt.%) in the absence of xanthan promoted the formation of aggregates of low molecular weight (160 kDa), the association of A an B polypeptides and a decrease in and ′ subunits. As DSP concentration of solutions increased, an increase in the proportion of aggregates of high molecular weight (above 200 kDa) and B-polypeptide was observed. On addition of xanthan (0.025 and 0.05%) to protein solutions (0.5 and 2%), the formation of aggregates of high molecular weight was favoured for both NSP and DSP. In the absence of xanthan, no preferential adsorption of soy polypeptides was observed at the air–water interface of NSP foams. However in DSP foams, there was a preferential adsorption of B-polypeptides. Xanthan present in NSP foams (0.5 or 2%), caused an increase in the proportion of aggregates of high molecular weight at the interface as compared with the composition of solutions used to make the foams. An increase in proportion of AB-polypeptides (for 0.5% NSP and 0.025% xanthan) and B-polypeptides together with polypeptides of molecular weight lower than 14 kDa (for 0.5% NSP and 0.05% xanthan) was also observed at the interface in NSP foams. On the contrary, the presence of xanthan in DSP foams caused a decrease in the proportion of aggregates of high molecular weight and a concomitant increase in B-polypeptide. The B-11S polypeptide predominated the interface of DSP foams probably for its hydrophobicity and basic characteristics.     

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.     

Pesticide residues in groundwaters and soils of agricultural areas in the Águeda River Basin from Spain and Portugal

This research has evaluated the agricultural impact of the use of pesticides in small agricultural areas in the Águeda river basin, which straddles the Spanish-Portuguese border. Sixteen pesticides frequently used in the area, including herbicides, fungicides and insecticides and some of their degradation products, were monitored in 52 groundwater samples and 42 soil samples taken around them, using a developed multi-residual analytical method based on SPE-LC-MS. Sampling was carried out in two different seasons (winter and summer). The results indicated the presence of pesticides at several levels, both in groundwaters and soils. Thirteen of the pesticides studied were detected in one or more of the groundwater samples analysed, but only three pesticides were detected in the soil samples. Terbuthylazine, cyprodinil, tebuconazole and chlorpyrifos were the pesticides most frequently detected in groundwaters, whereas terbuthylazine, metalaxyl and tebuconazole were the sole compounds detected in soils. The distribution of the concentrations in groundwaters indicated that up to 80% and 70% of the samples collected in the summer on the Spanish and Portuguese sides, respectively, exceed the quality standards of 0.1 µg L^?1 for one or more individual compounds and, in turn, up to 64% and 40% exceed the quality standards of 0.5 µg L^?1 for all compounds. The presence of pesticide residues in the groundwaters and soils analysed may well be explained by the use of these compounds in agricultural practices.     

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。     

本体与界面条件下MAPTMS水解-缩合过程中簇集行为比较研究

以甲基丙烯酰氧丙基三甲氧基硅烷(MAPTMS)为前驱体,利用荧光光谱、在线衰减全反射红外光谱(In-situ ATR-FT-IR),比较性地研究了在本体及气液界面条件下MAPTMS在酸性介质中的水解-缩合过程.借助于LB膜技术,测定了MAPTMS在气液界面水解-缩合反应过程中的π-A曲线.不论在本体相还是气液界面相,荧光探针芘均表现出明显的芘分子完全重叠及部分重叠的激基缔合物的荧光发射特征.结果表明:MAPTMS水解产物在水相中发生簇集,而且簇集体疏水端相互作用存在一定刚性.芘的荧光光谱随反应进行表现出显著变化,但本体相荧光光谱变化较气液界面相剧烈.ATR-FT-IR光谱在线检测表明:本体水解缩合产物具有较高的聚合度,而气液界面水解缩合产物聚合度较低.上述结果说明体系中存在簇集行为的显著变化,且在气液界面MAPTMS水解产物受限程度比本体相大.分子在气液界面上的聚集行为也由-πA曲线的结果得到进一步证实.文中依据MAPTMS水解产物具有类似表面活性剂的特性对上述实验结果给予了解释.     

Effect of pulp composition on the characteristics of residuals in CMC made from such pulps

Four different spruce sulphite pulp samples were used for the preparation of carboxymethylcellulose (CMC). The characteristics of the unreacted fibre and particle residuals obtained in the CMC-preparation were used to establish a correlation between the hemicellulose in the pulp and the intrinsic viscosity, i.e.,␣cellulose chain length and the occurence of unreacted residuals. It was shown that the residual particles in the CMC consisted of fibres, fibre fractions and gel particles of different degrees of substitution. The results suggested that pulps with long cellulose chains, i.e., pulps with high intrinsic viscosities, resulted in particles that were more substituted and more swollen. These pulps also resulted in more substituted hemicelluloses in the CMC and more substituted residuals. It was also suggested that galactoglucomannan in the cellulose pulps is favourable for the swelling which results in more substituted hemicelluloses in the CMC and more swollen residuals. The amount of residuals was influenced mainly by the characteristics of the cellulose in the pulp. It is therefore believed that a combination of high viscosity and a suitable combination of hemicelluloses is the most favourable way of eliminating the occurrence of undissolved residuals in CMC.