Comparison of two methods of detection,determination, and library search of the substances present in gas chromatography—mass spectrometry data

A comparison is made of two different methods, LIANAL and MSSMET, for the analysis of a g.c.—m.s. data matrix for the purpose of detecting and determining the metabolic profiles of the substances present. The parameters of the methods and the profiles determined on two different data matrices are compared. The two methods agree in 92 out of a possible 103 instances as to the presence or absence of the 103 substances for which they both made determinations. Ratios of the metabolic profiles for the two samples are highly correlated (0.9954) for the two methods.     

Development and publication of new gravimetric methods of analysis

A review is made of the factors affecting the accuracy of gravimetric methods, and which need to be investigated in the development of new methods. Recommendations are made for writing up such investigations for publication.     

Utilization methods for machine parts made of polymer-composite materials

The problem of the utilization of items made of polymer-composite material (PCM) is considered. The physical, chemical, and thermal utilization methods for machine parts made of PCM are detailed. Their advantages and disadvantages are described.     

橡胶贮存寿命预测方法研究进展与思考建议

概述了用数学模型法预测橡胶贮存寿命的方法,包括阿伦尼斯模型,用ASTM D412评估橡胶拉伸性能,应力应变老化模型,压缩永久变形的预测方法,橡胶疲劳寿命损伤模型,用有限元法考核橡胶的裂纹长度与抗裂能之间的关系,基于叠加原理的寿命预测模型等,针对上述模型预测研究结果提出了相关思考建议。认为以老化动力学为基础预测材料寿命的数学模型法发展非常迅速,建议深入研究并拓宽应用;在透彻了解和掌握必需的分子结构参数的基础上,如果结合计算机技术模拟长期贮存或使用条件,对橡胶老化反应机理的研究可能是一个有前景的发展方向。     

Analytical isotachophoresis in biological monitoring of exposure to industrial chemicals

Isotachophoretic methods for the determination of compounds of interest in biological monitoring are reviewed. The analytes are charged biotransformation products such as acids or amines. Comparisons are made between isotachophoretic methods and other techniques regarding sensitivity, need for preseparation or derivatization and similar technical aspects.     

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.     

Development and publication of new methods in kinetic analysis

A review is made of the various factors, such as the mathematical basis, measurement instrumentation, reaction mechanism, synergistic effects, etc, affecting the accuracy and precision of kinetic-based analytical methods. Recommendations are made concerning the research involved in developing new methods and/or applications and concerning the manner of presentation of the results for publication.     

Equivalence volumes in potentiometric titrations

The development of methods for finding the equivalence volume by using linear regression methods is reviewed. The methods discussed are mainly those developed and used at the Department of Analytical Chemistry at the Royal Institute of Technology in Stockholm. No attempt has been made to cover the large number of methods of finding the equivalence volume in potentiometric titrations developed elsewhere.     

High-performance liquid chromatographic methods for the determination of sulfonamides in tissue, milk and eggs.

In the last decade, significant research has been done to improve the existing high-performance liquid chromatographic (HPLC) methods and also towards developing simple, reliable and sensitive HPLC methods for sulfonamides in meat, milk and eggs. The replacement of solvent extraction with solid-phase extraction or matrix solid-phase dispersion techniques is a step forward. Significant improvements in sensitivity have been achieved. This review concentrates on HPLC methods for the determination of sulfonamides in foods of animal origin published after 1980. The existing methods are critically evaluated and suggestions for future research are made.     

Modified carbon-containing electrodes in stripping voltammetry of metals. Part II. Composite and microelectrodes

The second part of the review, which covers modified carbon-containing electrodes, describes composite and microelectrodes. Electrodes made of commercial and laboratory carbon-containing composite materials are discussed. Impregnated and thick-film electrodes and microelectrodes made of carbon fibers form a separate group. Various modifiers and methods of electrode modification are presented. Prospects for the future development of solid-state modified electrodes are considered.     

Calibration transfer for excitation-emission fluorescence measurements

The main part of the wide array of different calibration transfer methods found in literature is dedicated to two-way data arrangements (m×n matrices). Less work has been done within the area of calibration transfer for three-way data structures (m×n×l tensors) such as calibrations made for excitation-emission-matrix (EEM) fluorescence spectra. There are two possible ways to attack the problem for EEM transfer. Either the tensors are unfolded to two-way data, whereby the existing methods can be applied, or new methods dedicated to three-way calibration transfer have to be developed. This paper presents and compares both. It was possible to make a local linear pixel-based model that could be used for transfer of EEM's. This new method has a similar performance to the classical methods found in literature, direct- and piecewise direct standardization. The three-way advantages made it possible to use as few as four samples to build useable transfer models. Care has to be taken though when choosing the samples. When subset recalibration of the systems is compared to calibration transfer, better performance is seen for the transferred calibrations. Overall the three-way calibration transfer methods have a slightly better performance than the two-way methods.     

Extreme trace analysis of the elements-I Methods and problems of sample treatment, separation and enrichment

In the determination of elements in the ppM range in inorganic and organic matrices, solution techniques are useful because they simplify calibration problems and improve the limit of detection. The author reviews, in the light of his own experience, some 350 publications concerned with methods for the preparation and dissolution of samples and for the isolation of trace elements before their determination. The errors in these methods, made more difficult to reduce because of the additional operations required, are compared with those associated with the more direct methods.     

Chemical phase-analysis of ores and rocks: a review of methods

The methods employed in the chemical phase-analysis of rocks, ores and their treatment products are reviewed. An attempt has been made to be critical, selective and thorough in the choice of methods available in the literature, in order to provide a convenient manual for workers interested in this aspect of analytical chemistry.     

New directions in the analysis of biomacromolecules — an overview of three recent developments

HPLC, biospecific affinity chromatography and electrophoresis have already made substantial contributions to the analysis of biomacromolecules. As further refinements are made in these methods, they will become routine tools for probing both the structure and function of such molecules.     

Development and publication of new polarographic and related methods of analysis

A review is made of the factors that should be investigated in the development of new polarographic methods of analysis. Recommendations are made concerning the preparation for publication of the results of such investigations.     

Combination of nanofluid and inserts for heat transfer enhancement

Improving heat transfer is a critical subject for energy conservation systems which directly affects economic efficiency of these systems. There are active and passive methods which can be employed to enhance the rate of heat transfer without reducing the general efficiency of the energy conservation systems. Among these methods, passive techniques are more cost-effective and reliable in comparison with active ones as they have no moving parts. To achieve further improvements in heat transfer performances, some researchers combined passive techniques. This article performs a review of the literature on the area of heat transfer improvement employing a combination of nanofluid and inserts. Inserts are baffles, twisted tape, vortex generators, and wire coil inserts. The progress made and the current challenges for each combined system are discussed, and some conclusions and suggestions are made for future research.

     

Biodegradable Polyesters for Tissue Engineering

Summary: Paper describes basic characteristics of synthesis and properties of aliphatic polyesters used for tissue engineering. Described is also synthesis of polyester containing block copolymers suitable for surface modification. Described are methods used for scaffold fabrication with required porosity. In particular, presented are methods according to which scaffolds are made from prefabricated polyester micro- and nanoparticles.     

Measurement of spontaneous polarization in ferroelectric smectic liquid crystals

This paper presents measurements of spontaneous polarization made on two ester-bridged materials (SCE1 and CE8). The two materials are chosen to be representative of long pitch (SCE1) and short pitch (CE8) materials. The measurements were made by two different methods, Diamant bridge and field reversal; these methods are compared and the results shown to be in good agreement. The variation in results between different samples of these materials is discussed and the results compared (where possible) with the work of other authors. Special attention is paid to the variation which occurs between the published spontaneous polarization measurements of different authors. The reasons for this variation are examined and variation in sample alignment and the determination of the transition temperature by different authors are shown to be major causes.     

Multiple grid methods for classical molecular dynamics

Presented in the context of classical molecular mechanics and dynamics are multilevel summation methods for the fast calculation of energies/forces for pairwise interactions, which are based on the hierarchical interpolation of interaction potentials on multiple grids. The concepts and details underlying multigrid interpolation are described. For integration of molecular dynamics the use of different time steps for different interactions allows longer time steps for many of the interactions, and this can be combined with multiple grids in space. Comparison is made to the fast multipole method, and evidence is presented suggesting that for molecular simulations multigrid methods may be superior to the fast multipole method and other tree methods.