发铅检测法的临床应用价值评估

从铅中毒发铅诊断标准、发铅诊断试验及发铅诊断临床应用3个方面论述了发铅检测法在铅中毒诊断、筛查和监督中的实际应用问题。根据临床经验和发铅-血铅比值确定了居民发铅正常值上限及铅中毒发铅诊断分级标准;即使以血铅测定值为"金标准",诊断试验表明,发铅测定在铅中毒诊断中仍有实际应用价值;发铅检测法自上世纪60年代以来一直沿用至今,绝大多数研究者认为,发铅测定是诊断、筛查铅中毒和监督环境铅污染最简单、有效的工具。     

A study of storage conditions and treatments for forensic bone specimens using thermogravimetric analysis

Bone provides an important source of forensic evidence. The storage conditions of bone have been recognised as a factor in maintaining the integrity of such evidence. Thermogravimetric analysis (TG) has been employed to examine the effects of storage environments and preparation methods on the structural properties of pig bones. A comparison of oven and freeze drying has been made to study the effect of storage conditions. A comparison has also been made of ground bone specimens with cut specimens. Freeze-dried hand ground specimens provided the most consistent results and, thus, this is the recommended method of preparation of bone specimens for TG analysis.     

Heterogeneous strategies for selective conversion of lignocellulosic polysaccharides

Cellulose - Lignocellulosic biomass is the most abundant renewable carbon resource on earth, for which many efforts have been made to convert it using various chemocatalytic processes....     

八十年代海洋天然有机化学的进展

八十年代以来,海洋天然有机化学仍然继续发展,大量新的化合物,尤其是具有生理活性的化合物不断出现,海洋天然物的生物合成和人工合成研究也有新的进展。在海洋生物中,研究得最多的是海藻和海绵,其次便是珊瑚。     

A study of some matrix effects in the determination of beryllium by atomic-absorption spectroscopy in the nitrous oxide-acetylene flame

A study has been made of a number of interferences observed in the trace determination of beryllium by atomic-absorption in the nitrous oxide-acetylene flame. The major negative interference caused by the presence of excess of aluminium salts may be overcome by the use of 8-hydroxyquinoline. Magnesium and silicon also depress the Be signal, but most other metals cause enhancement. In most instances the enhancements may be made uniform by the addition of potassium ions to the sample solution.     

The error in absorption measurements, caused by the use of non-monochromatic light-II Gaussian functions

The errors in absorption measurements in spectrophotometry, caused by the use of non-monochromatic light, have been calculated. Gaussian functions have been assumed for the wavelength-dependence of the intensity of the incident light falling on the cell and the absorbance of the compound measured. Results found are similar to those found with parabolic functions. Experiments have been made to compare the results of the calculations with experimental values. The agreement is fairly good in most cases.     

Advances in enantiomeric resolution on monolithic chiral stationary phases in liquid chromatography and electrochromatography

During the last decade, chiral monolithic stationary phases have been prepared and used for rapid enantioseparations in CEC and HPLC. Various chiral selectors are used to prepare these CSPs. The preparation, properties, and applications of these CSPs are discussed in this paper. Attempts have been made to describe optimization strategies and the chiral recognition mechanisms. A comparison of chiral separations in CEC and HPLC is described. Efforts have also been made to predict the future perspectives and challenges of chiral monolithic stationary phases. The most effective chiral selectors include polysaccharides, cyclodextrins, and macrocyclic glycopeptide antibiotics. These chiral phases produced acceptable analytical enantiomeric separation of a variety of racemates. However, the development of these CSPs for preparative‐scale separations is needed.     

Spectral-luminescent analysis of sugar cane juice

A spectral-luminescent analysis has been made of the low-, medium-, and high-molecular mass fractions of sugar cane juice. The presence of pigments was detected in all the fractions. The medium-molecular-mass fraction was distinguished by the most considerable and most diverse composition of the pigments, a substantial contribution to which was made by the products of the alkaline decomposition of sugars. The amounts of pigments in all the fractions of the juice depended on the age of the plant. A pronounced dependence on the age of the plant was characteristic for the medium-molecular-mass fraction.     

国外聚乙烯催化工艺研究进展

聚乙烯(PE)以其性优、价廉的优势,成为通用合成树脂中产量最大的品种,主要包括低密度聚乙烯(LDPE)、线性低密度聚乙烯(LLDPE)、高密度聚乙烯(HDPE)、中密度聚乙烯(MDPE)、以及一些具有特殊性能的专用料树脂。催化剂是聚烯烃工业的核心,通过调控活性中心和改善聚合工艺,提高了催化剂活性,完善了所得聚烯烃的性能,推动了聚乙烯工业的蓬勃发展。研发特殊性能或优异性能聚烯烃树脂的催化剂,是目前聚烯烃领域关注的焦点。本文对近年来国外聚乙烯催化剂的研究进展进行了综述,重点阐述了目前研究开发中的催化工艺,涵盖了Ziegler-Natta催化剂、铬催化剂、茂金属催化剂、过渡金属催化剂以及制备双峰或宽峰分布聚烯烃的复合催化剂等;对各类新型催化剂的制备方法和工艺特点进行了总结,同时指明了相关工艺的研发公司,以便国内相关研究部门借鉴。     

Recent progresses on diarylethene based photochromic switches

Organic photochromic materials have received considerable attention because of their potential for photonic applications, especially for fast and high density data storage. In 2000, Chemical Reviews published a special issue on photochromic materials including a review about the properties and applications of diarylethene photochromic compounds. Since then much impressive progress has been made in this area. Various new diarylethene derivatives have been prepared and examined. The tutorial review presented herein describes developments in diarylethene-based molecular switches made in the last three years. In addition, the synthetic aspects of diarylethene photochromic compounds, which are important issues and neglected in most previous reviews, have been included.     

New polyimide ultrafiltration membranes for organic use

A solvent-resistant membrane for use in ultrafiltration processes has recently been developed by Nitro. The membrane is made from a new polyimide that can be synthesized from 1,2,3,4-butane tetracarboxylic acid and an aromatic diamine. This membrane exhibits excellent stability and high fluxes with most common organic solvents, even when tested at elevated temperatures.     

Theoretical descriptions of membrane filtration of colloids and fine particles: An assessment and review

Membrane separation technology is a novel and highly innovative process engineering operation. Membrane processes exist for most of the fluid separations encountered in industry. The most widely used are membrane ultrafiltration and microfiltration, pressure driven processes which are capable of separating particles in the approximate size ranges of 1 to 100 nm and 0.1 to 10 μm, respectively.The design of membrane separation processes, like all other processes, requires quantitative expressions relating material properties to separation performance. The factors controlling the performance of ultra- and microfiltration are extensively reviewed. There have been a number of seminal approaches in this field. Most have been based on the rate limiting effects of the concentration polarisation of the separated colloids at the membrane surface. Various rigorous, empirical and intuitive models exist, which have been critically assessed in terms of their predictive capability and applicability. The decision as to which of the membrane filtration models is the most correct in predicting permeation rates is a matter of difficulty and appears to depend on the nature of the dispersion to separated. Recommendations are made as to which of the existing models can be most appropriately applied to different types of dispersions.     

混合物定性定量分析的分枝定界算法

已知被测体系可能存在的物种范围, 但其确含何种物质及相应浓度必须经分析方可确定, 实为分析化学实践中常见的一类分析体系。基于分枝定界原理, 本文提出一种直接对其进行定性定量解析的光谱多元分析算法, 可显著减少计算量,却无失去真实信息的风险。对实际紫外可见及荧光混合物光谱进行解析, 均获满意结果。     

Chromatographic determination of the mycotoxin patulin in fruit and fruit juices

Patulin is a mycotoxin produced by several fungal species of the genera Penicillium and Aspergillus, but principally by Penicillium expansum on fruit such as apples. The occurrence of patulin as a natural contaminant of apple juice is a worldwide problem and international recommendations and regulations have been made for maximum levels permitted in consumer products. This paper reviews currently available analytical methods for its determination in fruit and fruit juices. Of these, HPLC with ultraviolet or, preferably, photodiode array detection is most widely used, although GC and TLC methods have also been described.     

Kinetic Methods of Analysis: How Do They Rate?

During the past few years there has been a resurgence of interest in kinetic aspects of analytical chemistry and in kinetic methods of analysis. The increased activity is a result of advances that have been made in instrumentation and in data processing techniques. Still, the kinetic approach is not widely applied by practicing analytical chemists. Why is this true? Why are kinetic methods not among the most common methods in use by analytical chemistry? This paper discusses the advantages and limitations of kinetic methods and addresses the probable reasons that they are not widely used. Several new principles have cmerged that are guiding the development of new kinetic-based determinations. These developments have made it possible to compensate for errors that result from changes in reaction conditions and to determine accurately multiple components in mixtures. With these advances kinetic methods are approaching the reliability of traditional equilibrium-based determinations and should be re-evaluated by analytical chemists.     

Recent progress in copper catalyzed asymmetric Henry reaction

Henry reaction is one of the most classical reactions to construct synthetically useful product nitro alcohol, which as a privileged skeleton is widely distributed in various pharmaceuticals. This review summarizes the recent progress of copper-catalyzed asymmetric Henry reaction from 2011 to 2016. The significant progress that has been made in this area will be highlighted and some of challenges that the author believes may be hindering further progress will be revealed.     

Organic Dyes in Laser Technology

Laser technology has been developed to a very high level since 1960. Significant advances have been made possible only by the use of organic dyes as optical shutters for the production of giant pulses. Ultrashort pulses in the picosecond range were first produced in 1966; their measurement was greatly facilitated by the use of organic dyes. Probably the most important recent advance in the laser field is the dye laser, which was first described in 1966, and in which the active medium is a solution of an organic dye.     

Approaches to Carbocyclic Sialidase Inhibitors Invited Review

 The crucial role played by carbohydrates in many physiological processes has made this class of compounds an interesting target for drug design. Consequently mimicking carbohydrates has been one of the most rapidly growing fields in synthetic organic chemistry in recent years, and particularly intense focus has been devoted to sialic acids and sialic acid metabolizing enzymes, including sialidases. Inhibition of the latter enzyme from influenza virus can be regarded as one of the most successful examples of structure-based drug design and high affinity inhibitors based on neuraminic acid have been developed. There is an ongoing search for inhibitors with improved physicochemical properties and among them, carbocyclic systems, where the ring oxygen of the carbohydrate is replaced by carbon, have become the center of interest. This review intends to give a brief overview over the structures and synthetic approaches which surfaced in the last decade.     

Smoke suppression for polystyrene

Studies have been made of the smoke-forming tendency of burning polystyrene and of the influence thereon of some established flame retardants, of a non-aromatic polymer and of a number of relatively unreactive oxides and other similar materials. The flame retardants generally increase smoke formation but decrease the rate of consumption of the polymer and, in order to separate the two effects, measurements have been made of the maximum amount of smoke generated and of the quantity of smoke formed per unit weight of polystyrene burnt. The incorporation of high-density polyethylene does not significantly reduce smoke production until a substantial proportion of the aromatic polymer has been replaced. At the relatively low levels used, most of the inert solids decrease only slowly both flammability and smoke formation but pyrogenic silica, even when present in very small concentrations, has a striking smoke-suppressant influence, the magnitude of which is directly related to its total available surface area.