STRUCTURE AND HARDNESS OF THE QUENCHED Mn–39 %Cu–2 %Ni–1.5 %Al–1 %Fe ALLOY DEPENDING ON THE DEGREE OF COLD PLASTIC DEFORMATION

The effect of the degree of cold plastic deformation on the structure and hardness of the hardened cast alloy Mn–39 %Cu–2 %Ni–1.5 %Al–1 %Fe is studied.It is shown that with an increase in the degree of deformation, the alloy hardness increases, the alloy structure becomes quasilayered, and the layer thickness decreases with an increase in the degree of deformation.Изучено влияние степени холодной пластической деформации на структуру и твердость литого закаленного сплава Mn–39 %Cu–2 %Ni– 1,5 %Al– 1 %Fe. Показано, что при увеличении степени деформациитвердость сплава увеличивается, структура сплава становится квазислоистой, а толщина слоев уменьшается с увеличением степени деформации

Inner relaxations in equiatomic single phase high entropy cantor alloy

The superior properties of high entropy multi functional materials are strongly connected with their atomic heterogeneity through many different local atomic interactions. The detailed element specific studies on a local scale can provide insight into the primary arrangements of atoms in multicomponent systems and benefit to unravel the role of individual components in certain macroscopic properties of complex compounds. Herein, multi edge X ray absorption spectroscopy combined with reverse Monte Carlo simulations was used to explore a homogeneity of the local crystallographic ordering and specific structure relaxations of each constituent in the equiatomic single phase face centered cubic CrMnFeCoNi high entropy alloy at room temperature. Within the considered fitting approach, all five elements of the alloy were found to be distributed at the nodes of the fcc lattice without any signatures of the additional phases at the atomic scale and exhibit very close statistically averaged interatomic distances 2.54 2.55 with their nearest neighbors. Enlarged structural displacements were found solely for Cr atoms. The macroscopic magnetic properties probed by conventional magnetometry demonstrate no opening of the hysteresis loops at 5 K and illustrate a complex character of the long range magnetic order after field assisted cooling in 5 T. The observed magnetic behavior is assigned to effects related to structural relaxations of Cr. Besides, the advantages and limitations of the reverse Monte Carlo approach to studies of multicomponent systems like high entropy alloys are highlighte

Intramolecular crossover from unconventional diamagnetism to paramagnetism of palladium ions probed by soft X-ray magnetic circular dichroism

The case of palladium(II) ions in molecular polyoxopalladates highlights the importance of accounting not only for nearest neighbour atoms or ions in order to understand, model or predict magnetic characteristics. Here, using site-specific soft X-ray magnetic circular dichroism (XMCD), the effects of different bond lengths, delocalization of 4d electrons, and 4d spin-orbit coupling on the electronic and magnetic properties are investigated and three different states identified: Conventional diamagnetism in a square-planar O4 coordination environment, paramagnetism caused by four additional out-of-plane oxygen anions, and an unusual diamagnetic state in the diamagnetic/paramagnetic crossover region modified by significant mixing of states and facilitated by the substantial 4d spin-orbit coupling. The two diamagnetic states can be distinguished by characteristic XMCD fine structures, thereby overcoming the common limitation of XMCD to ferro-/ferrimagnetic and paramagnetic materials in external magnetic fields. The qualitative interpretation of the results is corroborated by simulations based on charge transfer multiplet calculations and density functional theory results

DISSOLUTION MEDIA USED IN DEVELOPMENT AND QUALITY CONTROL OF DRUGS

The main dissolution media recommended for the Dissolution test in Russia and abroad are represented in the review. Possible applications of biorelevant media and media with surfactants are also shown. Based on the analysis of dissolution media authors concluded that it’s necessary to select appropriate dissolution conditions for particular drug. These dissolution conditions should be able to ensure the stability of the active pharmaceutical ingredients throughout the whole stage of the study. Moreover, when developing a dissolution medium, the researcher needs to take into account the chemical structure of the active pharmaceutical ingredients in the drug, the composition of the auxiliary substances and the site of the gastrointestinal tract, where the API dissolves

Features of the theories of the formation of oxide films on aluminum alloys piston diesel engines with micro-arc oxidation

The article considers one of the promising methods of surface hardening of piston aluminum alloy – microarc oxidation. Described fundamental differences from the micro-arc oxidation anodizing and similar electrochemical processes. The schemes of formation of the barrier and outer layers surface treatment in aqueous electrolytes. Shows the mechanism of formation of the interface. Considers the formation of layers with high porosity and method of exposure. Also describes the exponential dependence of the current density from the electric field in the surface film of the base metal. The role of discharges in the formation of oxide layers on the treated surface. Proposed and described features of the three main theories of formation of oxide films on the surface of the piston: physical and geometrical model of Keller; models of formation of oxide films as a colloid formations and plasma theory (theory of oxidation with the formation of plasma in the zone of oxidation). The features of formation of films in each of the models. For the model of Keller porous oxide film is a close-Packed oxide cell, having the shape of a prism. They are based on a hexagonal prism. These cells have normal orientation to the surface of the metal. In the center of the unit cell there is one season that is a channel, whose size is determined by the composition of the electrolyte, the chemical composition of the base metal and the electrical parameters of the process of oxidation. In the micro-arc oxidation process according to this model, the beginning of the formation of cells occurs with the formation of the barrier layer, passing in the porous layer and, over time, the elonga-tion of the pores, due to the constant etching electrolyte. In the theory of formation of the oxide films as kolloidnyh formations revealed that formation of pores in the film is a result of their growth. The anodic oxide is represented by a directed electric field, the alumina gel colloidal and polymeric nature. Plasma theory explains most of the issues related to the appearance of the characteristic luminescence with micro-arc oxidation. According to this theory, constantly ex-isting barrier layer is not present at the time of current interruption is polymerization from the attached directly to the anode thin layer of ionized gas. He is constantly in a state of seething and updates that explains the high rate of polym-erization and phase of aluminum oxide and heterogeneity parameters of the obtained anodic oxide thickness. The work also describes the main characteristics, which determine the rate of formation of oxide layers on the surface of alumi-num alloys

USE OF DISSOLUTION TEST FOR EVALUATION OF PHARMACEUTICAL EQUIVALENCE OF ATORVASTATIN GENERICS

This article shows the results of a study of pharmaceutical equivalence of atorvastatin generics using Dissolution test. A significant difference in the intensity of atorvastatin release from tablets from different manufacturers has been established. From 10 to 97% of atorvastatin was released from tablets of different manufacturers by the 15th minute of the test. In the similitude of the dissolution profiles, 6 generics out of 13 studied were pharmaceutically equivalent to the reference drug in doses 10 mg and 20 mg. It is shown that the inclusion of disintegrants and solubilizers in the formulation leads to an increase in the release rate of the active pharmaceutical substance from the dosage form

ОЦЕНКА ФАРМАЦЕВТИЧЕСКОЙ ЭКВИВАЛЕНТНОСТИ СУППОЗИТОРИЕВ НЕСТЕРОИДНЫХ ПРОТИВОВОСПАЛИТЕЛЬНЫХ СРЕДСТВ (НПВС) ПО ТЕСТУ «РАСТВОРЕНИЕ»

The article shows the results of a study of pharmaceutical equivalence of generic suppositories using Dissolution test. Objects: rectal suppositories of ketoprofen, diclofenac, indomethacin, paracetamol. Materials and methods: the Dissolution test was performed according to the method of United States Pharmacopoeia on the device Erweka DT 6, paddle apparatus (100 rpm), in dissolution medium of phosphate buffer solution (volume 900 ml, pH=7,2). Samples were collected after 15, 30, 45, 60 min after the start of the experiment. The quantity of ketoprofen, diclofenac, indomethacin, paracetamol was determined spectrophotometrically at wavelengths of 260 ±2 nm, 276 ±2 nm, 318 ±2 nm, 243 ±2 nm, respectively. As the reference solution used phosphate buffer solution (pH=7,2). A comparative evaluation of the equivalence of dissolution profiles of the drugs was performed by using the coefficients of the difference (f1) and similarity (f2). The study established the equivalence of ketoprofen suppositories of two, diclofenac – four, indomethacin and paracetamol  – three manufacturers.В статье представлены результаты исследования фармацевтической эквивалентности воспроизведенных суппозиториев по тесту «Растворение». Объекты: ректальные суппозитории кетопрофена, диклофенака, индометацина, парацетамола. Материалы и методы: испытание «Растворение» проводили по методике Американской фармакопеи на приборе Erweka DT 6, аппарат «лопастная мешалка» (100 об/мин), в среде фосфатного буферного раствора объемом 900 мл при рН=7,2. Отбор проб осуществляли через 15, 30, 45, 60 мин после начала эксперимента. Количество перешедшего в среду растворения кетопрофена, диклофенака, индометацина, парацетамола определяли спектрофотометрически при длинах волн 260 ±2 нм, 276 ±2 нм, 318 ±2 нм, 243 ±2 нм, соответственно. Раствором сравнения служил фосфатный буферный раствор (рН=7,2). Сравнительную оценку эквивалентности профилей растворения препаратов проводили с помощью коэффициентов различия (f1) и подобия (f2). В результате исследования установлена эквивалентность суппозиториев кетопрофена двух, диклофенака – четырех, индометацина и парацетамола  – трех производителей