Numerical solutions for isoelectric focusing and isotachophoresis problems

This study combines an adaptive mesh redistribution (AMR) method and the space–time conservation element and solution element (CESE) method to construct a high-resolution scheme for the solution of electrophoresis pre-concentration and separation problems. In the proposed AMR–CESE scheme, the fine mesh points are moved toward the regions of discontinuity within the solution domain in accordance with the equidistribution principle. To reduce the numerical dissipation within the regions of the solution domain with a large spatial mesh, the spatial component of the CESE scheme is treated using a Courant–Friedrichs–Lewy (CFL) number insensitive scheme. The validity of the proposed approach is confirmed by comparing the results obtained for typical isoelectric focusing (IEF) and isotachophoresis (ITP) problems with those obtained from the conventional CESE scheme and the finite volume method (FVM), respectively. It is shown that the AMR–CESE scheme yields a better accuracy than uniform fixed-mesh solvers with no more than a minor increase in the computational cost.     

An ultrasonic method for surface-active substances concentrating from aqueous solutions

Substances concentrated by surface sorption at a liquid-gas interface can be isolated by transforming the surface layer of the liquid using high-frequency focused ultrasound into an aerosol followed by aerosol condensation. The concentration of the surface substance in the obtained condensate is several times higher than in the initial solution. The effect was most pronounced at low contents of surface active component in the initial solution.     

Microfabricated devices for fluid mixing and their application for chemical synthesis

Over the last few decades, the processes of miniaturization, integration, and automation have revolutionized the world of science and industry. Within a chemical reaction process the unit operations, mixing, heating, and cooling, can be regarded as key steps. In microreactors, enhanced heat and mass transport, due to small characteristic dimensions together with large surface to volume ratios, are expected to open up a whole range of new possibilities. Increase in reaction yield, reduction of reaction time as well as byproduct formation, inherent process safety, and even completely new process routes are some of the advantages associated with microTAS (micro Total Analysis Systems) or microSYNTAS (micro SYNthesis Total Analysis Systems). This article aims to describe the development of microfabricated devices for fluid mixing, so-called micromixers, and their application for chemical synthesis.     

Carrier-bound biologically active substances and their applications

Stable catalysts can be obtained by fixation of enzymes on suitable supports. The principal methods for their preparation and their properties are described. The use of supported enzymes in routine biochemical analysis as “insoluble reagents” for automatic analyzers and for enzyme electrodes appears particularly interesting. For preparative transformations and syntheses, the supported enzymes offer the advantage that many processes that were formerly operated batch-wise can be run continuously to give protein-free products. The use of supported proteinases as specific adsorbents provides a simple method for the isolation of various naturally occurring inhibitors. This principle, which is the basis of affinity chromatography, has now also been adapted to the purification of enzymes and other biologically active substances on suitable supported effectors.     

Interstellar problems and matrix solutions.

The application of the matrix isolation technique, which is but one of the experimental techniques pioneered in George Pimentel's laboratories, to interstellar problems is described. Following a brief discussion of the interstellar medium (ISM) three areas are reviewed in which matrix experiments are particularly well-suited to contribute the information which is sorely needed to further our understanding of the ISM. The first involves the measurement of the spectroscopic properties of reactive species. The second is the determination of reaction rates and the elucidation of reaction pathways involving atoms, radicals and ions which are likely to interact on grain surfaces and in grain mantles. The third entails the determination of the spectroscopic, photochemical and photophysical properties of interstellar and cometary ice analogs. Significant, but limited, progress has been made in these three areas and a tremendous amount of work is required to fully address the variety of unique chemical and spectroscopic questions posed by the astronomical observations.     

Unconventional methods of initiating cationic polymerization using onium salts

Onium salts are latent sources of cationic species that can be released on demand to initiate cationic polymerizations by the application of various external physical and chemical stimuli. This paper will report on the use of several different types of stimuli to provide interesting and useful unconventional methods for initiating cationic polymerizations.     

The achievements and problems of the production of generic drug substances for pharmaceutical industry

Russian Chemical Bulletin - The key achievements, problems, and prospects of the pharmaceutical industry in the Russian Federation concerning the development, synthesis, and purification of active...     

Cure meters and their problems

The rate of cure of a rubber mix needs to be known for development and for quality control. This paper discusses the meaning of ‘rate of cure’, the methods of calculating it from cure-meter measurements and some of the problems involved, in particular the rate of attainment of the required temperature in the test piece.     

Magnetic field as a means to identify initiating reaction in oxidation of organic substances with molecular oxygen

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Rheological and volumetric properties of aqueous solutions of anionic polymer surface-active substances

The kinematic viscosity and density of diluted aqueous solutions of polymer anionic surface-active substances (ASASes) is studied in the temperature range of 298.15 to 323.15 K. The intrinsic viscosities, Huggins constants, apparent activation energies of viscous flow, and partial molar volumes at infinite dilution are determined for these systems. IR spectra of the investigated ASASes are obtained. The conformations of ASAS macromolecules in solution are corrected, based on an analysis of experimental data.     

Organic electronic devices and their functional interfaces.

A most appealing feature of the development of (opto)electronic devices based on conjugated organic materials is the highly visible link between fundamental research and technological advances. Improved understanding of organic material properties can often instantly be implemented in novel device architectures, which results in rapid progress in the performance and functionality of devices. An essential ingredient for this success is the strong interdisciplinary nature of the field of organic electronics, which brings together experts in chemistry, physics, and engineering, thus softening or even removing traditional boundaries between the disciplines. Naturally, a thorough comprehension of all properties of organic insulators, semiconductors, and conductors is the goal of current efforts. Furthermore, interfaces between dissimilar materials-organic/organic and organic/inorganic-are inherent in organic electronic devices. It has been recognized that these interfaces are a key for device function and efficiency, and detailed investigations of interface physics and chemistry are at the focus of research. Ultimately, a comprehensive understanding of phenomena at interfaces with organic materials will improve the rational design of highly functional organic electronic devices.     

Evolution of new narcotic substances and methods of their determination

History of the appearance and evolution of synthetic narcotics in recent years is presented. The main attention is paid to two classes of narcotic substances received the widest distribution in the world, i.e., cannabimetics and synthetic cations. The main classes, problems of identification, and approaches to the determination of new narcotics are considered. Approaches and solutions used in the quantitative analysis and screening of narcotics are discussed along with some aspects of sample preparation to their determination and matrix effects. The specific features of the determination of new narcotics in commercial products and biological samples are considered separately. Present-day methods of chromatography-mass spectrometry are most informative for timely revealing new narcotic substances, studying their metabolism, and developing reliable methods for the screening of native and biological samples.     

Supramolecular motifs in liquids. Aqueous solutions of organic substances

Different approaches to the analysis of the structure of condensed phases are briefly discussed. Introduced definition of the term “supramolecular motif” makes it possible to use this notion as a basis for finding correlations between structural peculiarities of the investigated systems and their properties. It is shown that the study of temperature dependences of the temperature coefficient of compressibility is a convenient way of detecting supramolecular motif (namely, framework of cooperative hydrogen bonds) in dilute aqueous solutions of organic substances.