On the modeling of phase and chemical equilibria by equations of state for systems containing supercritical components and ionic species

A technique of modeling of phase and chemical equilibria by equations of state for systems containing supercritical components and ionic species is considered. Attention is focused on the structure of equation of states with inclusion of non-electrolyte and electrostatic contributions. A hole quasichemical model was applied to illustrate the technique and to show how an EOS can be modified for systems with chemical reactions and electrostatic interactions in the liquid phase. The concentration dependency of the density and dielectric permittivity was taken into account in describing the electrostatic contribution that is required for thermodynamic consistency of the results of modeling. A method of assessing the appropriate relationships for mixtures containing supercritical components is suggested, alongside with the way to estimate the “true” composition of mixtures where ionic species are formed due to chemical reactions. The raised questions are discussed with respect to the following systems: solutions of acid gases in water-alkanolamine mixtures and water-ammonia-carbon dioxide system in a broad interval of temperatures and pressures.     

Intensifying the oxidation of isopropylbenzene

The reaction of liquid-phase oxidation of isopropylbenzene in the presence of nitrogen-containing catalysts at 110–130°C was studied. It was found that by using N-hydroxyphthalimide and its 3- and 4-methyl-substituted analogs, a 40–50% conversion of isopropylbenzene can be attained in 2–2.5 h with 90% selectivity of hydroperoxide formation. Considering the amount of phenol production, solving the problem of intensifying isopropylbenzene oxidation through the use of N-hydroxyphthalimide, thereby increasing the reaction rate and hydrocarbon conversion while retaining a high selectivity of hydroperoxide formation, could considerably enhance the economic parameters of the process.     

Hormonal regulation of anabolic processes and the rate of protein utilization in the early postnatal period

The levels of thyroid, pituitary and corticosteroid hormones--thyroxine, triiodthyronine, 11-oxicorticosteroids in blood serum, somatotropin in pituitary and processes of protein assimilation are studied in rats during early postnatal period. The highest endogen production of thyroxine, triiodthyronine and somatotropin is determined in 15 days old infant rats. The highest levels of protein utilization are determinated in 7-15 days old rats, then the process decreases with going over to definitive nutrition. Endogen production of anabolic hormones--thyroxine, triiodthyronine and somatotropin correlates to high levels of protein utilization in infant rats during the first days after birth.     

Experimental investigation of compact silicon carbide heat exchangers for high temperatures

The results of experimental investigations of novel ceramic high-temperature heat exchangers (HTHE) and its main characteristics such as effectiveness and power load as a function of mass flow and the geometry of the channels are presented. Firstly, some information on the background and the manufacturing of the HTHE, which is based on honey comb structures made out of extruded silicon carbide, is given. The experimental tests have been carried out with air as a heat transfer medium at temperatures of up to 1000 °C. The experimental set-up is described in detail. The acquired characteristic temperature and effectiveness data for different inlet temperatures and mass flows are discussed. They have been compared with data from theoretical calculations as well as with characteristic data of typical counter flow heat exchangers. Additionally, thermal shock tests have been carried out for a qualitative testing of the mechanical strength. Finally, a conclusion and an outlook on further activities are given.     

Synthesis,Structure, and Properties of Halloysite/Magnetite Composite

Protection of Metals and Physical Chemistry of Surfaces - Halloysite/magnetite composite was synthesized by chemical coprecipitation. To evaluate the crystal structure, texture, surface morphology,...     

Cytotoxic Potential of a-Azepano- and 3-Amino-3,4-SeCo-Triterpenoids

Semi-synthetic triterpenoids, holding an amino substituted seven-membered A-ring (azepano-ring), which could be synthesized from triterpenic oximes through a Beckmann type rearrangement followed by a reduction of lactame fragment, are considered to be novel promising agents exhibiting anti-microbial, alpha-glucosidase, and butyrylcholinesterase inhibitory activities. In this study, in an attempt to develop new antitumor candidates, a series of A-ring azepano- and 3-amino-3,4-seco-derivatives of betulin, oleanolic, ursolic, and glycyrrhetinic acids were evaluated for their cytotoxic activity against five human cancer cell lines and non-malignant mouse fibroblasts by means of a colorimetric sulforhodamine assay. Azepanoallobetulinic acid amide derivative 11 was the most cytotoxic compound of this series but showed little selectivity between the different human tumor cell lines. Flow cytometry experiments showed compound 11 to act mainly by apoptosis (44.3%) and late apoptosis (21.4%). The compounds were further screened at the National Cancer Institute towards a panel of 60 cancer cell lines. It was found that compounds 3, 4, 7, 8, 9, 11, 15, 16, 19, and 20 showed growth inhibitory (GI₅₀) against the most sensitive cell lines at submicromolar concentrations (0.20–0.94 μM), and their cytotoxic activity (LC₅₀) was also high (1–6 μM). Derivatives 3, 8, 11, 15, and 16 demonstrated a certain selectivity profile at GI₅₀ level from 5.16 to 9.56 towards K-562, CCRF-CEM, HL-60(TB), and RPMI-8226 (Leukemia), HT29 (Colon cancer), and OVCAR-4 (Ovarian cancer) cell lines. Selectivity indexes of azepanoerythrodiol 3 at TGI level ranged from 5.93 (CNS cancer cell lines SF-539, SNB-19 and SNB-75) to 14.89 for HCT-116 (colon cancer) with SI 9.56 at GI₅₀ level for the leukemia cell line K-562. The present study highlighted the importance of A-azepano-ring in the triterpenic core for the development of novel antitumor agents, and a future aim to increase the selectivity profile will thus lie in the area of modifications of azepano-triterpenic acids at their carboxyl group.     

The Development of a Method for the Production of Structural Polymeric Materials on the Basis of Norbornene Derivatives

Theoretical Foundations of Chemical Engineering - Process parameters of the polymerization of a mixture of exo,exo- and endo,endo-dimethyl esters of norbornene-2,3-dicarboxylic acid in the bulk of...     

New organometallic precursors and processes for chemical vapor deposition in the technology of nanomaterials

Processes of chemical vapor deposition (CVD) of metal and dielectric (high-k and low-k) films with the help of unconventional initial reagents (volatile complex and organoelement compounds) were developed. Complex investigation of the chemical and phase composition and structure of (HfO₂)_{1 ? x} (Me ₂O₃) _x double oxides (where Me = Al, Sc), and silicon carbonitrides and oxycarbonitrides was carried out. It was shown that the resulting materials enjoy a number of unique functional properties, which makes them promising for application in micro-, nano-, and optoelectronic devices.     

Low-temperature investigations of chemically deposited films of substitutional solid solutions based on lead and tin (II) selenides

Photoelectric characteristics of films of the Pb_0.902Sn_0.098Se solid solution based on the four-layer (SnSe-PbSe)₂ composition obtained by layer-by-layer hydrochemical synthesis with subsequent heat treatment in air within the temperature range 523–700 K are investigated. The measurements are performed in the temperature range 220–300 K. The thermal and optical band gaps, temperature coefficient of the optical band gap, dark resistance, volt-watt sensitivity, and spectral characteristics are determined. It is established that, at heat treatment temperatures below 573 K, the conductivity of the four-layer (SnSe-PbSe)₂ compositions is characteristic of metals, while at higher temperatures, it is characteristic of p-type semiconductors.