Prediction of Protein Sites and Physicochemical Properties Related to Functional Specificity

Specificity Determining Positions (SDPs) are protein sites responsible for functional specificity within a family of homologous proteins. These positions are extracted from a family’s multiple sequence alignment and complement the fully conserved positions as predictors of functional sites. SDP analysis is now routinely used for locating these specificity-related sites in families of proteins of biomedical or biotechnological interest with the aim of mutating them to switch specificities or design new ones. There are many different approaches for detecting these positions in multiple sequence alignments. Nevertheless, existing methods report the potential SDP positions but they do not provide any clue on the physicochemical basis behind the functional specificity, which has to be inferred a-posteriori by manually inspecting these positions in the alignment. In this work, a new methodology is presented that, concomitantly with the detection of the SDPs, automatically provides information on the amino-acid physicochemical properties more related to the change in specificity. This new method is applied to two different multiple sequence alignments of homologous of the well-studied RasH protein representing different cases of functional specificity and the results discussed in detail.

Obtaining Caustic Soda and Burkeite by Caustification of Mixture of Corbonate and Sodium Sulphate

The optimal technological parameters for the production of caustic soda from sodium carbonate and sulfate and calcium hydroxide have been established. The influence of the concentration of lime milk on the rate of filtration by sediment and filtrate has been studied. Purpose of the Work: The purpose of this work is to determine the physicochemical basis for the production of sodium hydroxide and burkeite by causticization of sodium carbonate and sulfate. Scientific Novelty: In comparison with the known works, a theoretical profoanalytical analysis of the one-cation of four-component system and its constituents was carried out for the first time, and also determined the optimal technological parameters of causticization of solutions for local carbonates and sodium sulfates. Features of the Work: - the influence of the main technological parameters on the processes of causticization, filtration, evaporation; - research of intermediate and finished products by modern physicochemical methods; - study of the rheological properties of the solution depending on the temperature and concentration of the resulting solutions.

Thermodynamics of Solid-Phase Exchange Reactions Limiting the Subsolidus Structure of the System MgO-Al2O3-FeO-TiO2

The basis of modern materials science is multicomponent systems, on their basis it is possible to create various combinations of phases in structural materials with a set of specified properties. The investigated system MgO-Al2O3-FeO-TiO2 is promising for the production of periclase-spinel refractories used as lining of rotary kilns during cement clinker firing, which are highly resistant to chemical corrosion when exposed to a gas environment and cement clinker components; thermomechanical stresses. However, in the reference literature and scientific articles, no information was found on the structure of the four-component diagram of the state of the MgO-Al2O3-FeO-TiO2 system, partial elements of its structure are given only in the composition of multicomponent systems [1-3]. Thus, research to the study of the subsolidus structure of the MgO-Al2O3-FeO-TiO2 system, which is the physicochemical basis for the development of compositions of periclase-spinel refractories, is urgent.

Phase equilibria in the CeO2–La2O3–Ln2O3 system at 1250 and 1500 °С

Materials based on cerium oxide, stabilized by oxides of rare earth elements, are promising for use in medicine, energy and mechanical engineering due to the uniqueness of their properties. State diagrams of CeO2–La2O3–Ln2O3 systems are the physicochemical basis for the creation of solid electrolytes for fuel cells, oxygen gas sensors, catalyst carriers, protective coatings on alloys, etc. Phase equilibria and structural transformations in CeO2–La2O3–Gd2O3 systems at temperatures 1250 and 1500 °С and in the binary system La2O3–Gd2O3 at temperatures 1100, 1500 and 1600 ° С in the whole range of concentrations were investigated using X-ray phase and microstructural analyzes. It was found that solid solutions based on cubic (F) modification with CeO2 fluorite type, monoclinic (B) and cubic (C) modifications of Gd2O3 and hexagonal (A) modification of La2O3 are formed in the ternary system CeO2–La2O3–Gd2O3. The boundaries of the phase fields and the periods of the crystal lattices of the formed phases are determined. It is established that in the CeO2–La2O3 –Gd2O3 system at 1250 and 1500 °С the phases of cubic symmetry are in equilibrium: on the basis of F–CeО2 with the spatial group Fm3m and C-phase on the basis of Gd2O3 with the spatial group Ia3. As the temperature decreases, there is a narrowing of all areas of homogeneity.

SUBSOLIDUS STRUCTURE OF THE MgO – FeO – Al2O3 SYSTEM

Three-component systems constitute the physicochemical basis of most refractory materials and the analysis of their subsolidus structure makes it possible to accurately predict the areas of compositions with optimal properties, as well as give recommendations on the technological parameters of production, sintering, and operation of the materials obtained. As a result of the carried out thermodynamic analysis of the MgO – FeO – Al2O3 system, it was found that the partition of the system into elementary triangles undergoes changes in two temperature ranges: I – up to a temperature of 1141 K and II – above a temperature of 1141 K. By calculation methods, the geometrical-topological characteristics of the subsolidus structure of the system are determined MgO – FeO – Al2O3: areas of elementary triangles, degree of their asymmetry, area of regions in which phases exist, probability of phase existence in the system. It has been established that, over the entire temperature range, there is a fairly extended concentration region of spinel phases: hercynite (FeAl2O4) – noble spinel (MgAl2O4). Moreover, periclase (MgO) coexists simultaneously with both spinels only in the low-temperature region. This indicates that when obtaining periclase-spinel refractories with increased heat resistance, an important technological parameter is a cooling rate below 1141 K. To obtain periclase-spinel refractories with branched microcracking of the structure due to differences in the thermal expansion coefficients of periclase, hercynite and noble spinel, the most rational concentration region of the system under study is which is common for two elementary triangles (MgO – FeAl2O4 – MgAl2O4 and MgO – FeO – MgAl2O4) existing in different temperature ranges. At high firing temperatures, the elementary triangle MgO – FeO – MgAl2O4 has a maximum area and a minimum degree of asymmetry, and upon cooling, MgO – FeAl2O4 – MgAl2O4 is formed, which is quite large in area, but has a high degree of asymmetry. Therefore, the composition of the charge for periclase-spinel refractories should be predicted with a high dosage accuracy and with a significant homogenization time of the components during mixing, since the concentration region common for both of the above elementary triangles is significantly reduced. Thus, the division of the MgO – FeO – Al2O3 system into elementary triangles and the analysis of the geometrical-topological characteristics of the phases of the system made it possible to select in the system under study the range of compositions with optimal properties for obtaining spinel-containing materials.

SOLUBILITIES OF COMPONENTS IN WATER SYSTEMS INCLUDING ETHANOL WITH CARBAMIDE AND UREA PHOSPHATE

This article presents the results of a study of the solubility of components in an aqueous system, including carbamide, ethanol and urea phosphate, which is a physicochemical basis for further development of the technology for the process of obtaining new complex-acting defoliants. It was found that the formation of studied new compounds does not occur in these systems. The components retain their individuality when present together.

Development of methods for analytical determination and extraction of cobalt(II) ions from aqueous solutions by melting organic reagents

Cobalt is a relatively rare metal, and its rich deposits are now almost exhausted. The main sources of industrial production of metallic cobalt are copper-nickel ores containing cobalt as an impurity. The processing of these ores is very complex and involves pyro- and hydrometallurgical methods depending on the composition of the ore. The result is a solution of cobalt and nickel chlorides containing impurities of copper(II), lead(II), bismuth(III) ions. Extraction is increasingly used to purify cobalt from associated impurities. Extraction methods are widely used in hydrometallurgy, the nuclear materials industry, the technology of rare metals and the production of highly pure substances, as well as in analytical chemistry. However, despite this they have a number of drawbacks the main one is the use of fire hazardous and toxic organic solvents; therefore, the principles of eliminating toxic components from the process are becoming more common. The physicochemical basis of the extraction of cobalt (II) ions was studied by a stearic acid melt.The possibilities of practical application are considered of research results. Solid extracts of cobalt(II) were obtained with low-melting organic extractants. They meet all the requirements of standard samples: they differ in homogeneity of distribution, in similarity of composition with the analyzed samples and they can be used for several years.