A Device for Measurements of Dielectric Characteristics of Liquid Crystalline Materials, Solid Substances, and Their Melts

The device developed allows one to measure the dielectric characteristics of solid substances and their melts at frequencies of 20–20000 Hz and in a wide temperature range of 20–250°C. The measured temperature dependencies of the dielectric permittivities of several molecular and liquid crystals (stilbene, diphenyl, naphthalene, cholesterylpelargonate, and 8OCB) are presented.     

Synthesis, characterization and catalytic application for wet oxidation of phenol of iron-containing clays

High-surface-area pillared clays (PILC) were prepared from naturally occurring montmorillonites by exchanging interlayer ions to polyoxocations containing (i) aluminum (Al₁₃-PILC), (ii) iron adsorpted onto Al₁₃-PILC, and (iii) iron and aluminum located within the same complex (Fe_0.8Al_12.2-PILC). The obtained Fe_0.8Al_12.2-PILCs were characterized by DR–UV–vis and IR spectroscopy, XRD, ESR, scanning electron microscopy and low temperature N₂ adsorption measurements. Important factors affecting catalyst activity and phenol removal efficiencies have been studied, i.e. the effect of pH, temperature, catalyst concentration and stability of the catalyst.     

Synthesis of phosphorus-, zinc-, and chlorine-containing poly(ethylene terephthalate)

Phosphorus-, zinc-, and chlorine-containing oligomer was used as a comonomer including ionic bonds in its molecules in the synthesis of poly(ethylene terephthalate). Phosphorus-, zinc-, and chlorine-containing poly(ethylene terephthalate) including ionic bonds in its main polymer chain was synthesized. With a content of 0.6% P and 1.25% Zn and 0.1% Cl, the resin has the following characteristics: η_rel = 1.407; COOH 39.90 mg equiv KOH/g 10^?6; and mp 255.8°C. The modifier acts as a thermostabilizer. © 1993 John Wiley & Sons, Inc.     

Development of methods of design,development, testing,and maintenance of real-time global space information-control systems

An approach to creation of real-time global space information-control systems referred to the class of complex systems based on methods of systems analysis, information technologies, and simulation, is considered. It is shown that objectives and tasks of any such system and requirements to it determine inevitable prior development of mathematical models of the system and of the environment realized on an imitation-simulation testbed, and a possibility of imitation testing with their help for more precise determination of characteristics of the system at all stages of its lifecycle. Particular examples of application of this approach are given.     

The vitamin allowance and vitamin requirements of the operators of a chemical plant in the city of Rustavi

Excretion of thiamine, riboflavin, N1-methyl nicotinamide and ascorbic acid with urine, TDP-effect, ascorbic acid and vitamin A content in the blood have shown higher vitamin requirements in the operators, as compared to subjects of the control group, this was caused by unfavourable effects of the chemical factors of the production environment. The levels of the biochemical parameters characterizing normal providing of the operators with vitamins could be achieved by additional vitamins administered to the workers (2 dragees of "Hexavitum").     

Characterization of nanoporous materials prepared from montmorillonite clay and its application to the decolorization of mare's milk oil

Nanoporous materials have been prepared by leaching the purified montmorillonite clay with sulfuric acid (H₂SO₄) solution with varying concentrations (0.5–2 M) at 80°C for 0.5–4 h. Acid leaching causes partial amorphisation of the clay with depletion of MgO, Al₂O₃, CaO and Fe₂O₃ components mostly from interlayer and octahedral sites. This increases the specific surface area by more than 3 times, i.e. from 49.1 to 157 m²/g. The pore-size distribution curves calculated from the adsorption isotherms of the leached montmorillonite show that most of the pores are in the mesoporous region with their diameter ranging 3–4 nm. This material turns out to be appropriate for bleaching of the mare's milk oil. The chemical and structural changes of the acid-leached montmorillonite are discussed in terms of the decolorization capacity.     

Effect of the electrolyte composition on In and Ag–In alloy electrodeposition from cyanide electrolytes

A procedure for preparation of clear and stable indium cyanide electrolytes, containing indium salt, d(+)-Glucose and KCN is proposed. NMR investigations revealed that the formation of a complicated indium complex in which the products of the disintegration of d(+)-Glucose in the KCN-solution are closely situated to the indium ion ensures the clearness of the electrolyte. The effect of nitrate, chloride and sulphate ions on the electrochemical processes of indium and silver–indium alloy electrodeposition is studied by cyclic voltammetry. During alloy electrodeposition under galvanostatic conditions unique spatio–temporal structures are observed on the cathodic surface.     

Design and experimental evaluation of robust controllers for a two-wheeled robot

The paper presents the design and experimental evaluation of two alternative μ-controllers for robust vertical stabilisation of a two-wheeled self-balancing robot. The controllers design is based on models derived by identification from closed-loop experimental data. In the first design, a signal-based uncertainty representation obtained directly from the identification procedure is used, which leads to a controller of order 29. In the second design the signal uncertainty is approximated by an input multiplicative uncertainty, which leads to a controller of order 50, subsequently reduced to 30. The performance of the two μ-controllers is compared with the performance of a conventional linear quadratic controller with 17th-order Kalman filter. A proportional-integral controller of the rotational motion around the vertical axis is implemented as well. The control code is generated using Simulink® controller models and is embedded in a digital signal processor. Results from the simulation of the closed-loop system as well as experimental results obtained during the real-time implementation of the designed controllers are given. The theoretical investigation and experimental results confirm that the closed-loop system achieves robust performance in respect to the uncertainties related to the identified robot model.     

Experiments on the synthesis of neutron-deficient isotopes of kurchatovium in reactions with accelerated50Ti ions

Conclusions A number of conclusions can be drawn from the aggregate of experimental results.The method of synthesis of transfermium elements in the irradiation of lead isotopes with ions with mass A_I40 atomic units, investigated earlier [12] for the example of the reaction Pb(⁴⁰Ar, xn)Fm, is also extremely effective using⁵⁰Ti ions. The reactions Pb(⁴⁰Ar, 2n)Fm and Pb(⁵⁰Ti, 2n)Ku have approximately equal cross sections, which might have been expected on the basis of theoretical estimates. This permits us to hope that this method can be used successfully for the synthesis of heavier elements in the reactions induced by⁵⁴Cr,⁵⁵Mn, and⁵⁸Fe ions.In all probability, the substantial changes in the systematics of the half-lives for even-even isotopes of kurchatovium are associated with the structure of the barriers to fission of these nuclei. From this standpoint, it seems important to investigate the properties of more neutron-deficient isotopes of kurchatovium, using, in particular, the reactions with²⁰⁴Pb, and to attempt to advance into the region of elements with Z 106. On the other hand, a detailed theoretical analysis must be made of the data obtained on the basis of the modern theory of nuclear fission, which, in our opinion, will aid in a more reliable prediction of the properties of heavy and ultraheavy elements.Translated from Atomnaya Énergiya, Vol. 38, No. 6, pp. 382–390, June, 1975.     

A new type of gas sensor based on the thermovoltaic effect in zinc oxide inhomogeneously doped with mixed-valence impurities

We propose a new type of potentiometric gas sensor operating on the basis of the thermovoltaic effect in uniformly heated (without temperature gradients) ZnO/ZnO–Fe sandwich structures obtained by the sol–gel method. It is established that a significant contribution to the gas responsivity of sensors is related to the thickness of the upper doped layer of the structure.