Surface and optical properties of calcium carbonate paper

The article investigates the surface and optical properties of calcium carbonate paper obtained at the UzbekChinese enterprise Fergana stone paper company (Uzbekistan), in order to identify the possibility of their use at printing enterprises for printing multicolor products using traditional printing methods. According to the results of a quantitative assessment of the surface quality by the indirect Beck method, we can say that paper sample 1 has a smoothness like coated paper (750–1500 s), paper samples 2 and 3 – like calendered paper, so that these paper samples can be recommended for prints with increased quality requirements. Smaller values of roughness Ra and small depressions, expressed by darkening in the topographic AFM images, characterized sufficient homogeneity and density of the structure. It was also revealed that the surface of the paper samples has a high ability to specularly reflect the incident light, since the percentage of surface reflection is similar to that of coated papers. Samples of paper have a whiteness of about 90 % and do not have a tint, since the difference between the maximum and minimum values of the reflection coefficients on a white stack is not more than 10 %. The tested paper samples can be recommended without restrictions for double-sided printing, since the opacity index is more than 92 %.

Heat-insulating porous material based on glauconite-containing sands and aleurites of the Novodvorskoye deposit of the Republic of Belarus

The results on the research of heat-insulating porous ceramic materials produced using overburden rocks of the Novodvorsk deposit of Pinsk district of the Brest region as the main component of raw materials are presented in the study and the use of bulk rock consisting of glauconite sands and aleurites is recommended. Low-melting clay, basalt and a blowing agent are used as additional components, rational combination of which would ensure the forming ability of ceramic masses and the required set of the physicochemical properties of the material. The dependence of the bulk density, swelling coefficient, coefficient of thermal conductivity on the chemical and mineral composition of the used and raw materials is established, wich is the criteria for choosing composition with the maximum use of overburden and the necessary plasticity of the ceramic mass required for the molding process of raw granules. The obtained results can serve as a basis for the large-scale use of not only the minerals of the Novodvorsk deposit (basalts and tuffs), but also associated – glauconite-containing overburden. This will make a significant contribution to the expanding the mineral resource base of the Republic of Belarus.

Synthesis of chalcone-based pyrimidine derivatives and their antimicrobial activity

A series of substituted chalcones and pyrimidine derivatives on their base was synthesized. Obtained compounds were tested for antimicrobial activity and ability to increase activity of known antimicrobial substances. Pyrimidine products shown good activity against Staphylococcus aureus and Candida tropicalis. These compounds also could increase activity of modified polyguanidines against Staphylococcus aureus.

Protective Langmuir–Blodgett coatings based on long-chain fatty acids

The morphology and tribotechnical properties of Langmuir–Blodgett (LB) monolayers and multilayers of some fatty acids, such as nervonic (NA), cerotic (CA) and montanic acids (OCA), was investigated. It was established that the wear resistance of silicon surface coated by LB monolayer of OCA is greater by 11 and 1.3 times in comparison with the LB monomolecular films of NA and CA, respectively. The multilayer of OCA, formed by 140 layers, increases the stability of steel surface by 35 times.

Enzymatic hydrolysis of plant raw materials: state and prospects

Plant raw materials are practically an inexhaustible natural resource, since they are constantly renewed in the process of plant photosynthesis, which determines the prospects for their use for industrial processing in various ways, including hydrolytic. The main biopolymer components of plant biomass in terms of their quantitative content are polysaccharides, the hydrolytic processing of which by acidic or enzymatic hydrolysis leads to the formation of monosaccharides and various products obtained from them. This review of scientific literature analyzes theoretical concepts and the current state of research on the development, improvement and prospects for the use of enzymatic hydrolysis of plant raw materials. The efficiency of this process and the composition of the resulting products largely depend on the features of the supramolecular structure of cellulose, the content of hemicelluloses and lignin in the raw material, the balance and activity of the cellulase complex of enzymes. It is shown that the main directions of development and improvement of the processes of enzymatic hydrolysis of plant raw materials at present are the production and use of more effective strains of microorganisms that produce highly active enzymes, the directed creation of complex enzymes (hydrolyzing not only cellulose, but also hemicellulose, as well as destroying lignin), the development of methods for pretreatment of raw materials to increase the reactivity of cellulose and remove lignin and improve the processes of fermentolysis.

Quantum-chemical modeling of cortisone-fullerenol agents of cancer therapy

In order to therapeutically destroy oncological neoplasms, chemotherapy or radiotherapy is usually applied, and in isotope medicine – short-lived radio nuclides are injected into the tumor (59Fe, 90Y, 95Zr, 99mTc, 106Ru, 114*In, 147Eu, 148Eu, 155Eu, 170Tm, 188Re, 210Po, 222Rn, 230U, 237Pu, 240Cm, 241Cm, 253Es). Binary (or neutron capture) therapy is a technology developed for the selective effect on malignant tumors using drugs that are tropic to tumors and contain non-radioactive nuclides (10B, 113Cd, 157Gd at al.). Triadic therapy involves the sequential introduction into the body of a combination of two or more separately inactive and harmless components, which are tropic to tumor tissues and capable of selectively accumulating in them or chemically interacting with each other and destroying tumor neoplasms under the action of certain sensitizing external influences. The aim of this work is quantum-chemical simulation of the electronic structure and analysis of the thermodynamic stability of new cortisone-fullerenol agents for the treatment of tumor neoplasms. The need for preliminary studies of modeling such objects is due to the very high labor intensity, cost and complexity of their practical production.

Titration of weak base fibrous anion exchangers in the presence of complex-forming divalent cations

Curves of potentiometric titration of fully protonized fibrous ion exchangers with potassium hydroxide against the background of 1 M KCl in the presence of chlorides of Ni2+, Со2+, Сu2+ and Ca2+ were obtained. The ion exchangers were synthesized by modifying of industrial polyacrylonitrile fiber with diethylenetriamine and triethylenetetraamine and predominantly contained functional groups R-CO-NH- (CH2CH2NH)nH (n = 2 or 3) and a small amount of carboxyl groups. The sorption of Ni2+, Со2+, Сu2+ и Ca2+by ion exchangers was calculated from the data obtained depending on the pH of the medium. It was found that the investigated ion exchangers with high selectivity sorb heavy metal ions in a wide range of acidity of solutions (pH 2–9) due to the formation of metal-polymer complexes with polyamine functional groups. The maximum sorption capacity is 1.5–2.7 and 4–5 meq/g for ion exchangers with n = 2 and 3, respectively.

On water solubility of С17–С24 alkylbenzolsulphoic acids used as an additive to motor oils

Using the nephelometric method, the water solubility of C17–C24 alkylbenzenesulfonic acids has been studied. The results of the study made it possible to develop a technique for measuring the solubility of alkylbenzenesulfonic acids used in the production of additives for motor oils. Using the methodology in scientific and industrial laboratories, it is possible to determine the content of ABSA in mixtures with water and to qualify this substance according to the criterion of water solubility when assigning the appropriate code in the Commodity Nomenclature of Foreign Economic Activity.

Nanocomposites based on apatitic tricalcium phosphate and autofibrin

Nanocomposites based on apatitic tricalcium phosphate in an autofibrin matrix were obtained by precipitation at a Ca/P ratio of 1.50, pH 9 and a maturation time from 30 min to 7–14 days. The resorbability of nanocomposites was determined by the composition of calcium phosphates, which, during long-term maturation, formed as the calcium-deficient hydroxyapatite with a Ca/P ratio of 1.66, whereas biopolymer matrix favored the formation of more soluble calcium phosphates with a Ca/P ratio of 1.53–1.59. It was found that the fibrin clot stabilized, along with apatitic tricalcium phosphate, the phase of amorphous calcium phosphate, which after 800 °C was transformed into resorbable α-tricalcium phosphate. Citrated plasma inhibited the conversion of apatitic tricalcium phosphate into stoichiometric hydroxyapatite, which also facilitated the formation of resorbable β-tricalcium phosphate after 800 °C. The combined effect of the maturation time and the biopolymer matrix determined the composition, physicochemical and morphological properties of nanocomposites and the possibililty to control its extent of resorption

Synthesis of new thiazolo[3,2-a]pyrimidine derivatives and in silico analysis of their bioactivity

An effective method of synthesis thiazolo[3,2-a]pyrimidine derivatives was developed and the compounds with n-pentyl or β-acetoxycyclopropyl as well as fluorescent benzo[f]coumarin substituents were obtained with yields 60 % and more. Using computational (in silico) approaches we demonstrated the ability of the obtained compounds to permeate lipid bilayer as well as their affinity to some protein kinases (compounds 4 and 6 bind with a protein kinase AKT1 with PDB code 3о96; Autodock Vina-computed energy of binding (Ebind) values were -10.9 and -10.6 kcal/mol, respectively), acethylcholine esterase and some human cytochromes P450 (for P450 3A4, pdb 5vcd, Ebind -12.3 kcal/mol).