For the elemental analysis of candidates for reference materials of black shale composition - SLg-1A and SChS-1A - inductively coupled plasma mass spectrometry (ICP-MS) was used after fusing the samples with lithium metaborate and microwave acid decomposition without preliminary ashing. The proposed sample preparation methods are characterized by speed and ease of implementation, and made it possible to use ICP-MS to determine a wide range of elements in each sample, including Cd, Mo, Sb, Sn, Te, W, Tl, Bi, data on the content of which were previously unavailable or were estimated approximately during the certification of SLg-1 and SChS-1. The determination of analyte concentrations was performed within a single measurement cycle on the magnetic sector mass spectrometer ELEMENT in low, medium and high resolution using external calibration with solutions of similar matrix composition in combination with an internal standard to reduce non-spectral matrix influence. The relative standard deviation of ICP-MS analysis for most elements after fusion is less than 10%, after acid decomposition from 6 to 20%. The necessity of increasing the sample weight to 1 g has been experimentally established to ensure the representativeness of the sample during ICP-MS determination of Ag and Au in samples.
Based on an analysis of historical (including archival) documents, it is shown that the chemical aspect of research conducted in the laboratory of agronomic chemistry for the study of soils at Moscow University in 1890s - 1920s included training students in analytical methods for determining the content of various substances in soils, as well as a few research works on the study of the heat capacity of soils and the structure of humic substances.
Comprehensive immunophenotyping of sarcoma cell cultures was performed for expression of tumor markers associated with key biological characteristics of malignant neoplasms: TUBB3, EMT/MET, PD-L1, ERα, and ERβ. Two pairs of cell cultures with differences in molecular phenotype were formed: metastatic Mg-63 vs. primary MNNG-Hos osteosarcoma and Mg-63 osteosarcoma vs. HT-1080 fibrosarcoma. These pairs may be useful for assessing the contribution of the studied markers to various biological characteristics of tumor cells and studying the interactions between their regulatory mechanisms in mesenchymal tumors.
Since its discovery in 1946, nuclear magnetic resonance spectroscopy become as a method to solve structural and dynamic problems in modern chemistry. Currently, it is hard to find a university in the world without various NMR spectrometers in its laboratories. Achievements in this field, over the course of almost 80 years of its development, were recognized with four Nobel Prizes in Physics and Chemistry. Fifth-generation high-resolution NMR spectrometers were developed during this period. They are as complex measurement and computing systems, in which the latest advances in electronics, cryogenics, and computing technology are utilized. Scientists from the USSR and Russia made the significant contributions to this remarkably rapid progress. This year marks the 60th anniversary of the establishment of the first NMR laboratory at the Faculty of Chemistry of Moscow State University that focused to solve complex chemical problems. The history of its creation and several scientific projects to solve not only specific chemical problems but to develop an NMR methodological arsenal are described in this work.
The phenomenon of metal concentration by plants is discussed. The metal content in plants can be tens or hundreds of times higher than the metal content in the soil. A kinetic model of phytomining is developed. The model is verified based on experimental data, the two-chamber nature of the process is demonstrated, a parametric analysis of the model is performed elucidating the role of the metal transfer rate from the geological substrate and metal translocation in the plant, and the dynamics of metal bioaccumulation is described. Natural coals are characterized by exceptionally high ash content (metal content up to 50
Based on the adhesion tension isotherms γLVcosθ = f(γLV), the relationship between the adsorption values of surfactants at the solution/solid surface (ГSL) and solution/air (ГLV) interfaces was examined by wetting Teflon and polystyrene with aqueous solutions of the nonionic surfactant Triton X-100 (TX-100). The approach presented in this paper demonstrates the feasibility of predicting the wettability of hydrophobic surfaces for practical applications, using an existing database on the surface tension of aqueous surfactant solutions and their adsorption on the surface of solid adsorbents.
In the green bacteria Chlorofl exus aurantiacus, the process of photosynthesis begins with the absorption of light by unique light-harvesting complexes, chlorosomes, which consist of ~104 bacteriochlorophyll (BChl) c molecules combined into complex spatial structures. Upon absorption of blue light (~460 nm) by the B band of chlorosomes, ultrafast energy conversion occurs, resulting in the excitation of the red Qy band (~740 nm). We studied this process using difference (light-dark) absorption spectroscopy with a high time resolution (20 fs). We have found that the characteristic conversion time is 35 fs. We have shown that energy conversion precedes slower processes of exciton relaxation in the Qy band (100–300 fs) and energy transfer from the chlorosome to the baseplate and further to the reaction center (tens of ps). The physicochemical foundations of intramolecular energy conversion in chlorosomes and the signifi cance of this process for photosynthesis are discussed.
The review presents the history of research on the luciferin-luciferase system of fi refl ies Luciola mingrelica at the Department of Chemical Enzymology of MGU, which began in the mid-70s of the last century on the initiative of the fi rst head of the Department, Professor I.V. Berezin. Based on the study of the kinetics of enzymatic oxidation of luciferin, a kinetic scheme of the reaction was proposed, according to which in an aqueous solution the luciferase reaction is a non-stationary enzymatic process, the turnover of the enzyme is very small due to the slow dissociation of the enzyme-product complex. Analysis of the bioluminescence and fl uorescence spectra of the reaction product – oxyluciferin – and its analogues led to the conclusion. that ketoenol tautomers of the phenolate forms of oxyluciferin (ketone, enol and enolate ion) are the most likely emitters in the luciferin-luciferase system of fi refl ies. Native luciferase preparations have been shown to contain phospholipids, the removal of which leads to a decrease in the activity and stability of the enzyme. At the beginning of the 90s, luciferase L. mingrelica was cloned. The enzyme in the primary sequence turned out to be close to other luciferases of the genus Luciola, cloned in Japan (more than 80% homology), but differed from the previously studied luciferase from american P. pyralis fi refl y (67% homology). Using methods of random and site-specifi c mutagenesis, a library of mutant forms of L. mingrelica luciferase with altered bioluminescence spectra (“green” and “red” luciferases) was created. Thermostable mutants of luciferase were obtained by the method of directed evolution, in particular, a highly active and thermostable mutant (4TS), on the basis of which an ATP-reagent was developed, which is still widely used in bioluminescent analysis by many researchers in our country. Methods of genetic engineering, computer modeling and site-specifi c mutagenesis have been used to clarify the role of the dynamic structure of the enzyme in the complex, three-stage oxidation of the luciferin. It has been shown that the emitter (electronically excited oxyluciferin) is an intramolecular label in the enzyme active site. The superposition of two or three emitter forms fi xed in the bioluminescence spectra indicates the coexistence of various conformational forms of luciferase in the reaction medium, which are in dynamic equilibrium.
The problem of poor solubility in water, which usually negatively affects the bioavailability of oral medications, is a characteristic of most molecules (up to 70%) developed as active pharmaceutical ingredients (API). Amorphous solid dispersions of N-butyl-N-methyl-1-phenylpyrrolo[1,2-a]pyrazine-3-carboxamide (GML-3) with Soluplus® polymer have been developed. The inclusion of GML-3, which is practically insoluble in water and has an antidepressant and anxiolytic effects in solid dispersions, made it possible to transfer it from a crystalline to an amorphous state. The amorphousness of solid dispersions was confi rmed by powder X-ray diffractometry (PXRD) and differential scanning calorimetry (DSC), and the interaction of polymer and GML-3 inside the dispersions was revealed. As a result of studying the effect of amorphous solid dispersions with Soluplus® on the dissolution kinetics of GML-3, it was possible to achieve the solubility of GML-3 in water at the level of 98,4%, which solves the problem of the solubility of the API.
A method for determining nitrate in soil by digital colorimetry is proposed. The developed approach is based on appropriate photometric techniques of nitrate determination after potassium chloride extraction from soil samples. The original method of determining nitrate in the form of an azo dye formed by the azo coupling reaction between 1-naphtylamine and sulfanilamide has been modifi ed to achieve a higher sensitivity and accuracy of colorimetric determination. This approach ensures metrological characteristics of the digital colorimetric technique, close to spectrophotometric. The adequacy of the proposed method was confi rmed by analyzing standard samples and soil samples collected in districts of the Moscow region.
Predicting and optimizing the photophysical properties of retinal containing channel proteins under two-photon absorption (TPA) conditions are required for their efficient use in optogenetics. Nonlinear two-photon excitation can also lead to photoactivation of visual rhodopsins in the IR range of 950–1000 nm. Here, by using high-level quantum chemistry calculations, we explore the factors that influence the TPA activity of the type I and type II rhodopsins upon their two photon resonant excitation to the first singlet excited state. We show that in the case of the S0 → S1 transition, the channels through permanent dipole moments, which are associated with the initial and final states only, make the largest contribution to the calculated TPA cross-sections. The fast numerical convergence of the sum-over-states formalism provides direct evidence for the applicability of the two-level model for calculating TPA cross-sections in rhodopsins, which are characterized by the large transition dipole moment and a signifi cant redistribution of the electron density upon the S0 → S1 transition. The calculated TPA cross-sections (340–610 GM) are found to be very sensitive to changes in the permanent dipole moments between the ground and excited states and highly tunable by internal electric f i eld of the protein environment. The high tunability of the nonlinear photophysical properties of the retinal protonated Schiff-base chromophore can be used for the rational design of retinal-containing proteins with optimal photoresponse.
Self-organization of selenohydantoin on the gold surface was studied using contact angle measurements and Quartz Crystal Microbalance. Optimal conditions for the formation of a dense monolayer on the metal surface were determined, and the possibility of obtaining a metal complex surface during complexation of Cu(Ⅱ) ions with a monolayer fi xed on the surface was demonstrated.
Herein, we report about polymer-colloid drug carriers based on water-soluble, biocompatible, biodegradable anionic polysaccharides such as sodium alginate and sodium hyaluronate kross-linked with calcium and magnesium ions. Doxorubicin characterized by fluorescent properties was used as a drug for immobilization by the prepared nanocontainers. An approach to quantitative determination of thermodynamic constants of doxorubicin binding to nanocontainers and linear polysaccharides was proposed, which is based on the ability of nanocontainers to quench fluorescence of doxorubicin during interaction. The proposed approach allowed to quantitatively assessing the ability of nanocontainers to retain doxorubicin immobilized.
Synthesis and regrouping reaction of 2-methoxyphenylchloracetate in the presence of small quantities of catalysts were investigated. In the result of this reaction o - and p -hydroxyphenylchlorides were obtained. Method of meta methoxyphenylchloracetate obtain was developed and it was shown that it can be obtain by chloracetylation of meta -methoxyphenol in benzol solution. For the fi rst time regrouping of meta -methoxyphenylchloracetate in the presence of small quantities of FeCl3, MoCl5, WCl6, ZnCl2, SnCl4, VCl3, FeCl3·6H2O, Fe2(SO4)3, FАА (ferrum acetylacetonat), FSА (ferrum salisylat) was carried out. In the result of this reaction 2-hydroxy-4-methoxyphenacylchloride and 4-hydroxy-2methoxyphenacylchloride were obtained. The percentage ratio of obtained isomers depends on the conditions of carrying out of the reaction. Study of the synthesis 4- methoxyphenylchloroacetate and it’s of the reaction diphenyltiokarbazone in presence of dimethylformamide. The structure of the obtained materials are installed by means of UF-, IR- and NMR- spectroscopy.
The interaction of AB5 type alloys intended for work in arctic conditions with hydrogen was studied. Thermodynamic parameters of hydrogen absorption and desorption reactions were established and the effect of alloying with manganese and aluminum on them was determined. Experimental data are compared with those calculated using a statistical forecast model.
New documents from the archival fund of Academician N.S. Zefi rov in the Archive of the Russian Academy of Sciences are presented. They allow to trace his relationship with his mentor, Professor Yu.K. Yuryev of Moscow University.
In this work, for the first time, an elemental analysis of thyme grass (creeping thyme, lat. Thymus serpyllum L.), growing on the territory of the Chuvash Republic (Cheboksary), was carried out using the X-ray fluorescence method. In the studied samples, among the 22 chemical elements detected, potassium, calcium, phosphorus, silicon and iron had higher content. Macroelements by content in mg/kg can be arranged in the following descending order: K (12410) > Ca (8960) > P (6000) >S (1480) > Cl (1280). The content of microelements in thyme herb samples in descending order looks like this: Si (7590) > Fe (350) > Mn (80) > Zn (30) > Sr (20) > Cu, Br (10). Titanium (40 mg/kg), rubidium and chromium (10 mg/kg) were found in the samples. There are no toxic elements (cadmium, lead, mercury and arsenic), as well as silver, zirconium and vanadium in the samples. The elemental composition of Chuvash thyme was compared with samples from the Goris region of Armenia and medicinal and herbal raw materials from manufacturers Phytopharm LLC (Krasnodar Territory, Anapa) and Zdorovye LLC (Moscow region). The absence of heavy toxic metals and arsenic, the rich macro- and microelement composition of Chuvash thyme herb make it possible to recommend it as a medicinal and herbal raw material for the production of various preparations for traditional and traditional medicine, cosmetology, perfumery, cooking, etc.
New data on the formation of the agronomic chemistry program at Moscow University are presented, and examples of educational manuals and research conducted at Moscow University in the 19th century are given.
The article is devoted to the development of a simple chromatographic analysis for the determination artificial sweetener sucralose at low concentrations in combined sweeteners. The method of hydrophilic interaction liquid chromatography (HILIC) using a silica with immobilized 2-hydroxyethyliminodiacetic acid (HEIDA) groups in La3+ form as a stationay phase is developed to determine low concentrations of sucralose in the presence of large excess of erythritol, using a relative preconcentration due to different solubility in acetonitrile. The best separation of sucralose and erythritol was achieved using a acetonitrile:water (95:5 vol.%) mixture as the mobile phase. The refractive index detector was used for quantitative determination of sucralose in combined sweeteners with limit of detection (LOD) of 28 μg/ml.
