Measurement of reflection coefficients of organic and non-organic media and materials in UV spectrum

Measurements of the diffuse reflection coefficients of organic and inorganic materials and media in solid, granular and liquid forms were made in the UV field of 230–400 nm. A single channel spectrometer with an integrating sphere was used. Relation between diffuse reflection coefficients and the structure and composition of the samples is discussed. These data allow us to estimate the prospect of machine vision systems application for the UV range in such areas as biology, geology, remote control of materials and media

Balancing Specificity and Promiscuity in Enzyme Evolution: Multidimensional Activity Transitions in the Alkaline Phosphatase Superfamily

Highly proficient, promiscuous enzymes can be springboards for functional evolution, able to avoid loss of function during adaptation by their capacity to promote multiple reactions. We employ systematic comparative study of structure, sequence and substrate specificity to track the evolution of specificity and reactivity between promiscuous members of clades of the alkaline phosphatase (AP) superfamily. Construction of a phylogenetic tree of protein sequences maps out the likely transition zone between arylsulfatases (ASs) and phosphonate monoester hydrolases (PMHs). Kinetic analysis shows that all enzymes characterized have four chemically distinct phospho- and sulfoesterase activities, with rate accelerations ranging from 1011-1017-fold for their primary and 109-1012-fold for their promiscuous reactions, suggesting that catalytic promiscuity is widespread in the AP-superfamily. This functional characterization and crystallography reveal a novel class of ASs that is so similar in sequence to known PMHs that it had not been recognized as having diverged in function. Based on analysis of snapshots of catalytic promiscuity ‘in transition’ we develop possible models that would allow functional evolution and determine scenarios for trade-off between multiple activities. For the new ASs we observe largely invariant substrate specificity that would facilitate the transition from ASs to PMHs via trade-off-free molecular exaptation, i.e. evolution without initial loss of primary activity and specificity toward the original substrate. This ability to bypass low activity generalists provides a molecular solution to avoid adaptive conflict.BBSR

Design and optimization of enzymatic activity in a de novo β-barrel scaffold

While native scaffolds offer a large diversity of shapes and topologies for enzyme engineering, their often unpredictable behavior in response to sequence modification makes de novo generated scaffolds an exciting alternative. Here we explore the customization of the backbone and sequence of a de novo designed eight stranded β-barrel protein to create catalysts for a retro-aldolase model reaction. We show that active and specific catalysts can be designed in this fold and use directed evolution to further optimize activity and stereoselectivity. Our results support previous suggestions that different folds have different inherent amenability to evolution and this property could account, in part, for the distribution of natural enzymes among different folds

Multifrequency EPR spectroscopy of Ho3+ ions in synthetic forsterite

Electron paramagnetic resonance (EPR) of Ho3+ single ions and Ho3+-Mg2+-vacancy-Ho3+ associates in holmium-doped forsterite single crystals are studied at 9.4, 37.3 and 65-250 GHz. Crystals were grown from melt by the Czochralski technique in slightly oxidizing atmosphere. For both centers, directions of the principal magnetic axes and parameters of the effective spin Hamiltonians describing dependences of electron-nuclear levels on applied magnetic field are obtained. For Ho 3+ substituting Mg2+ in the M2 site as the single ion and for Ho3+ ions in dimer centers, values of crystal field parameters related to a real crystal lattice structure are estimated in the framework of the exchange charge model. The calculated crystal field energies, values of the g-factors of the ground Ho3+ quasi-doublet and the directions of the corresponding magnetic moments agree satisfactorily with the data obtained from measurements of EPR and optical absorption and site-selective luminescence spectra. © Springer-Verlag 2005

Proton Conductivity of La2 (Hf2−x Lax )O7−x/2 “Stuffed” Pyrochlores

The design of new oxygen-and proton-conducting materials is of paramount importance for their possible utilization in solid oxide fuel cells. In the present work, La2 (Hf2–x Lax )O7–x/2 (x = 0, 0.1) ceramics were prepared using ball milling of oxide mixtures (La2 O3 and HfO2 ) followed by high-temperature annealing at 1600◦ C for 10 h in air. La2 Hf2 O7 ceramics exhibit an ordered pyrochlore-type structure, whereas La2 (Hf1.9 La0.1)O6.95 has a defect pyrochlore structure type with oxygen vacancies at the 48f positions. The oxygen ion and proton conductivity of La2 (Hf1.9 La0.1 )O6.95 “stuffed” pyrochlore ceramics was investigated by electrochemical impedance spectroscopy (two-probe AC) and four-probe DC measurements in a dry and a wet atmosphere (air and nitrogen). The use of two distinct conductivity measurement techniques ensured, for the first time, the collection of reliable data on the proton conductivity of the La2 (Hf1.9 La0.1)O6.95 “stuffed” hafnate pyrochlore. La2 Hf2 O7 was found to be a dielectric in the range 400–900◦ C, whereas the La2 (Hf1.9 La0.1 )O6.95 “stuffed” pyrochlore had both oxygen ion and proton conductivities in this temperature range. The proton conductivity level was found to be equal to ~8 × 10−5 S/cm at 700◦ C. Clearly, the proton conductivity of the La2 (Hf1.9 La0.1 )O6.95 “stuffed” hafnate pyrochlore is mainly due to the hydration of oxygen vacancies at 48f positions. © 2022 by the authors. Licensee MDPI, Basel, Switzerland

COMPLICATED DIAGNOSIS: RETROPERITONEAL ALVEOCOCCOSIS IN THE GUISE OF ORMOND’S DISEASE

Diagnosis of parasitic diseases, in a type of their rarity and diversity, always presents considerable difficulties. Clinical observation of an alveococcosis with invasion in the retroperitoneal space with distribution on mediastinal fat proceeding with progressing retroperitoneal fibrosis with ureteral obstruction and hydronephrosis development, with an aorta lumen stenosis, with formation of SVC syndrome in the absence of changes in other parts of the body, first of all in the liver, in the absence of eosinophilia in the peripheral blood throughout all disease and lack of antibodies to echinococci in the blood serum, twice during observation determined by an immunofermental method is presented in this article

Drug-Induced Atrial Fibrillation / Atrial Flutter

Drug-induced atrial fibrillation / flutter (DIAF) is a serious and potentially life-threatening complication of pharmacotherapy. Purpose of the work: systematization and analysis of scientific literature data on drugs, the use of which can cause the development of DIAF, as well as on epidemiology, pathophysiological mechanisms, risk factors, clinical picture, diagnosis and differential diagnosis, treatment and prevention of DIAF. Analysis of the literature has shown that many groups of drugs can cause the development of DIAF, with a greater frequency while taking anticancer drugs, drugs for the treatment of the cardiovascular, bronchopulmonary and central nervous systems. The mechanisms and main risk factors for the development of DIAF have not been finally established and are known only for certain drugs, therefore, this section requires further study. The main symptoms of DIAF are due to the severity of tachycardia and their influence on the parameters of central hemodynamics. For diagnosis, it is necessary to conduct an electrocardiogram (ECG) and Holter monitoring of an ECG and echocardiography. Differential diagnosis should be made with AF, which may be caused by other causes, as well as other rhythm and conduction disturbances. Successful treatment of DIAF is based on the principle of rapid recognition and immediate discontinuation of drugs (if possible), the use of which potentially caused the development of adverse drug reactions (ADR). The choice of management strategy: heart rate control or rhythm control, as well as the method of achievement (medication or non-medication), depends on the specific clinical situation. For the prevention of DIAF, it is necessary to instruct patients about possible symptoms and recommend self-monitoring of the pulse. It is important for practitioners to be wary of the risk of DIAF due to the variety of drugs that can potentially cause this ADR

Влияние химической структуры карбоксилсодержащих полимеров на морфологию осадков и устойчивость дисперсий карбонатов

The influence of the molecular structure of carboxyl-containing polymers on their inhibitory and stabilizing effect in the precipitation processes was studied using a number of polymeric acids with different contents of carboxyl groups (X): polyacrylic acid (Mn = 5100 g-mol–1, X = 61.11 %), polymethacrylic acid (Mn = 5500 g-mol–1, X = 48.79 %), copolymer of methacrylic acid with turpentine terpene (α-pinene) (Mn = 350 g-mol–1, X = 14.54 %). It has been established that polyacid molecules slow down the process of crystal growth and recrystallization of the amorphous phase into more stable crystalline forms, which leads to a change in the morphology and structure of a carbonate precipitate. It has also been shown that polycarboxylic acids increase the colloidal stability of a mixed dispersion of carbonates and kaolin. The synergism of the stabilizing effect of mixtures of different hydrophobicity-polyacids was noted: in the presence of a mixture of polyacrylic acid with a copolymer of methacrylic acid with turpentine terpene, the stabilization effect increases 2 times compared to dispersion without additives and 1.4–1.8 times compared with individual components of the mixture. С целью изучения влияния молекулярно-структурного строения карбоксилсодержащих полимеров на их ингибирующее и стабилизирующее действие в процессах осадкообразования был исследован ряд полимерных кислот с различным содержанием карбоксильных групп (Х): полиакриловая кислота (Мn = 5100 г-моль–1, Х = 61,11 %), полиметакриловая кислота (Мn = 5500 г-моль–1, Х = 48,79 %), сополимер метакриловой кислоты с терпеном скипидара (α-пинен) (Мn = 3500 г-моль–1, Х = 14,54 %). Установлено, что введение поликислот замедляет процесс роста кристаллов и приводит к изменению морфологии и структуры осадка карбонатов в результате рекристаллизации аморфной фазы в более устойчивые кристаллические формы. Показано, что поликарбоновые кислоты повышают коллоидную стабильность смешанной дисперсии карбонатов и каолина. Отмечен синергизм стабилизирующего действия смесей поликислот с различной гидрофобностью: в присутствии смеси полиакриловой кислоты с сополимером метакриловой кислоты с терпеном скипидара стабилизационный эффект возрастает 2 раза по сравнению с дисперсией без добавок и в 1,4–1,8 раза по сравнению с индивидуальными компонентами смеси.

Approbation of a prognostic model of commodity turnover of a pharmacy organization on the example of the Sysert urban district

The purpose of the study is to test the predictive model of the turnover of a pharmacy organization on the example of the Sysert urban district.Цель исследования – апробация прогностической модели товарооборота аптечной организации на примере Сысертского городского округа