Hall effect in the natural glassy carbon of schungites

The temperature dependences (80–500 K) of the Hall coefficient and the resistivity of samples of schungite of types I and III (schungite I and schungite III), as well as a commercial glassy carbon, with carbon contents equal to 98, 30, and 99.99%, respectively, are measured. The character of the dependences of the resistivity and its numerical values are similar to those observed in polycrystalline graphites with a high degree of disorder and in synthetic glassy carbon. Conversely, the Hall coefficient in the schungite samples, as in high-quality single crystals and n-type intercalated compounds of graphite, is found to be negative, small in magnitude, and weakly dependent on the temperature. At room temperature it is equal to 2.83×10⁻²² and 0.305 cm³/C in schungite I and schungite III, respectively, the Hall mobility of the charge carriers in these materials is 8.0 and 9.2 cm²/V·s, and the Hall carrier concentration is 2.2×10²⁰ and 2.0×10¹⁹ cm⁻³. Fiz. Tverd. Tela (St. Petersburg) 39, 1783–1786 (October 1997)     

Electroosmotic Circular Thin-Layer Chromatography

A new version of electroosmotic thin-layer chromatography, circular electroosmotic chromatography, was suggested and a prototype apparatus for its implementation was designed.     

The N-Chamber of the New Type for Rapid Thin-Layer Chromatography

The N-chamber, the most often in the method of thin-layer chromatography (TLC) for the separation, is used with the previous process of equilibrium saturation of the TLC plate with the mobile phase (MP) vapors, what, unfortunately, requires about 1 h. For the acceleration of the processes of saturation of the analytical plate with the vapors of the mobile phase, the use of a specially developed N-chamber of the new type containing a specific cassette holder has been proposed. In this cassette holder, a feeding plate (that is a TLC plate, previously wetted by MP) was additionally placed parallel to the analytical plate at a very small distance (0.2–1.0 mm). In these conditions, the process of saturation of the analytical plate with the MP vapors is accelerated substantially, and it passes with the improved repeatability. The new approach permitted to substantially (up to 2 times) decrease the time necessary for the TLC plate development in the N-chamber.     

Formation of microcrystalline structures in a flow of supersaturated HIO3 solution through the pores of track membranes

The formation of acicular microcrystals in the pores of a polyethylene terephthalate track membrane upon the filtration of a supersaturated aqueous HIO₃ solution is studied. The transverse sizes and directions of preferred growth of the formed edged microcrystals are found to correspond to the configuration of pores of the track membrane.     

Elastic properties of the Ta–V system: bcc Ta0.33V0.67 and C15 TaV2

Resonant ultrasound spectroscopy was used to measure the elastic constants of bcc Ta_0.33V_0.67 over the temperature range 3.5–300?K; the results were compared to earlier measurements on C15 TaV₂. The temperature dependence of the polycrystalline shear modulus is completely different in the two phases; that of the bcc phase decreases with temperature whereas that of the C15 phases increases in an anomalous fashion. This difference is consistent with a model involving doubly-degenerate levels at the X point of the Brillouin zone in the C15 phase with the Fermi level lying near the doubly degenerate level. This model accounted for the unusual behaviour of the C15 phase. Debye temperatures were determined from the ultrasonic measurements: 295?K for the C15 phase and 315?K for the bcc phase.     

What Is Chromatography? Reply to a Critical Paper by V.A. Davankov

Based on well-known logical concepts, a polysemic definition of the notion of chromatographygiven in a compendium of scientific terminology of the Russian Academy of Sciences is considered to be incorrect. The interpretation of column walls as a stationary phase in field-flow fractionation (FFF), suggested by Professor V.A. Davankov, seems logically unfounded. This is because column walls in FFF and a stationary phase in traditional versions of chromatography are different in all principal characteristics (functions, forms, and operands). Thus, the opinion of the author of the FFF method, J.C. Giddings, who considered FFF as a version of one-phase chromatography, should not be considered as erroneous, as Professor Davankov believes.Precise logical definitions of concepts are a fundamental prerequisite to true knowledge.Socrates     

Three-Dimensional Thin-Layer Chromatography on Plates with Open and Closed Adsorption Layers

JPC – Journal of Planar Chromatography – Modern TLC - Two variants of three-dimensional thin-layer chromatography were realized using plates with open and sealed (closed) adsorption...     

Ammonia as carrier gas in capillary gas-liquid chromatography.

Influence of helium and ammonia as carrier gases on retention of neutral solutes on polyethylene glycol has been studied theoretically and experimentally. It was shown that the influence of ammonia on the retention varied significantly depending on the solute's nature. For example, the influence is great for C22 n-alkane and it is small for phenol. Taking into account the results obtained by various researchers it makes sense to express an opinion on the expediency of development of gas chromatography operated under the conditions of acidic-basic chromatography.