Structural heterogeneity and diffuse scattering in morphotropic lead zirconate-titanate single crystals

Complementary diffuse and inelastic synchrotron X-ray scattering measurements of lead zirconate-titanate single crystals with composition near the morphotropic phase boundary (x=0.475) are reported. In the temperature range 293 K < T < 400 K a highly anisotropic quasielastic diffuse scattering is observed. Above 400 K this scattering disappears. Its main features can be reproduced by model of inhomogeneous lattice deformations caused by inclusions of a tetragonal phase into a rhombohedral or monoclinic phase. This observation supports the idea that PZT at its morphotropic phase boundary is essentially structurally inhomogeneous.Comment: 4 pages, 4 figure

Моделирование процессов деформирования и разрушения нанокомпозитов Al/Cu

The aim of this work is to carry out molecular dynamics simulation of the uniaxial stretching of a cooled Al/Cu composition. The LAMMPS software package has been used for calculations, which includes the classic molecular dynamics code with an emphasis on modeling materials. The Ovito program has been used for visualization, which has a large number of functions, so that the user can thoroughly investigate the results obtained. When describing the interatomic interaction in the Al/Cu nanocomposite, we used the potential of the embedded EAM atom. The choice of potential is due to the fact that it adequately describes and reproduces the properties of a wide class of materials, including metals, semiconductors and alloys. The simulation has been carried out in two stages. At the first stage, a sample consisting of two crystallites of aluminum and copper in the form of parallelepipeds, connected along one of the joint boundaries, was placed in the computational domain and cooled at constant pressure. Cooling was carried out to stabilize the nanosystem. At the second stage, corresponding to the deformation, the temperature and pressure were changed in accordance with the ongoing physical processes. The algorithm of the thermostat and the Nose – Hoover barostat has been used to control the temperature and pressure at the initial stage of cooling. The paper demonstrates the nature of the distribution of longitudinal stresses over the entire volume of the crystal in the process of stretching. When the sample reached the elastic limit, the nucleation of crystal lattice defects and their distribution over the crystal in the form of shifts and rotations of atoms in crystal planes were observed. Areas of plastic deformation origin have been determined. The maximum destruction of the material occurred along the interface. The parameters of the Al/Cu composition (deformation, temperature, mechanical stress) have been dynamically investigated using molecular dynamics simulation. Comparison of the characteristics of the sample in the deformation process has been carried. Under loading conditions, a variety of processes are implemented in the material, including generation of defects, elastic and plastic deformation, generation of damage, and mechanical mixing.Проведено молекулярно-динамическое моделирование одноосного растяжения охлажденной композиции Al/Cu. При расчетах использовали программный комплекс LAMMPS, включающий в себя классический код молекулярной динамики с акцентом на моделирование материалов. Для визуализации применяли программу Ovito, имеющую большое количество функций, благодаря чему пользователь может тщательно исследовать полученные результаты. При описании межатомного взаимодействия в нанокомпозите Al/Cu использовали потенциал погруженного атома EAM. Выбор потенциала обусловлен тем, что он адекватно описывает и воспроизводит свойства широкого класса материалов, в том числе металлов, полупроводников и сплавов. Моделирование осуществлялось в два этапа. На первом образец, состоящий из двух кристаллитов алюминия и меди в форме параллелепипедов, соединенных вдоль одной из сводных границ, размещался в расчетной области и охлаждался при постоянном давлении. Охлаждение осуществлялось для стабилизации наносистемы. На втором этапе, соответствующем деформации, температура и давление менялись в соответствии с протекающими физическими процессами. Для управления температурой и давлением на начальной стадии охлаждения использовали алгоритм термостата и баростата Нозе – Гувера. В статье продемонстрирован характер распределения продольных напряжений по всему объему кристалла в процессе растяжения. При достижении образцом предела упругости наблюдались зарождение дефектов кристаллической решетки и распространение их по кристаллу в виде сдвигов и поворотов атомов в кристаллических плоскостях. Определены области зарождения пластических деформаций. Максимальное разрушение материала происходило по границе раздела. С помощью молекулярно-динамического моделирования динамически исследованы параметры композиции Al/Cu (деформация, температура, механическое напряжение). Проведено сопоставление характеристик образца при деформации. В условиях нагружения в материале реализуется множество процессов, включающих в себя генерацию дефектов, упругую и пластическую деформации, генерацию повреждений и механическое перемешивание

Temperature Evolution of Sodium Nitrite Structure in a Restricted Geometry

The NaNO$_{2}$ nanocomposite ferroelectric material in porous glass was studied by neutron diffraction. For the first time the details of the crystal structure including positions and anisotropic thermal parameters were determined for the solid material, embedded in a porous matrix, in ferro- and paraelectric phases. It is demonstrated that in the ferroelectric phase the structure is consistent with bulk data but above transition temperature the giant growth of amplitudes of thermal vibrations is observed, resulting in the formation of a "premelted state". Such a conclusion is in a good agreement with the results of dielectric measurements published earlier.Comment: 4 pages, 4 figure

Experience of using multielectrode catheter systems to perform radiofrequency renal sympathetic denervation in patients with resistant hypertension: immediate procedural effects

Aim. To investigate the baseline characteristics of patients with resistant hypertension (HTN) undergoing radiofrequency renal sympathetic denervation (RD) and to determine immediate procedural effects.Material and methods. During 2018-2019, two series of radiofrequency RD procedures were performed in patients with true resistant HTN using balloon-type (bipolar ablation) or spiral-type (unipolar ablation) multielectorde catheters. The basic demographic, clinical and laboratory characteristics of included patients were assessed. A comparative analysis of two groups was carried out depending on the type of catheter used. Dynamics of office systolic blood pressure (SBP) were assessed as ∆ between the two following timepoints: at screening and at hospital discharge. The safety of radiofrequency RD was assessed. Multiple linear regression was used to determine the factors associated with the ∆ of office SBP after radiofrequency RD.Results. A total of 48 patients taking 4 (4;6) antihypertensive drugs were sequentially included. Radiofrequency RD was performed with a balloon-type catheter in 27 patients (mean age, 56±12 years old; 12 males) and with a spiral-type catheter in 21 patients (50±14 years old; 8 males). Radiofrequency RD was significantly longer in the spiral catheter group than in balloon one (110 versus 60 minutes, p&lt;0,001), as was the mean number of RF applications (24 versus 12, p=0,002). None of the patients had acute kidney injury after RD (creatinine ∆, -0,6 µmol/L; 95% CI [-3,97; 2,78]). A total of 4 patients had complications (3 femoral arterial pseudoaneurisms, one renal arterial dissection), all of which did not affect the average length of hospital stay (from 4 to 5 days). At discharge, there was a pronounced decrease in office SBP (adjusted for baseline characteristics) with the mean of -26 mm Hg (95% CI [-29; -23]). There were following main factors associated with the office SBP ∆: smoking status (positive), baseline office SBP (positive), and blood glucose (negative).Conclusion. Radiofrequency RD using multielectode catheters is characterized by favorable short-term hemodynamic effects. We have found novel potential predictors of these effects. Further research will focus on testing initial hypotheses in the long term

Сравнительное исследование процесса хондрогенной дифференцировки мезенхимальных стромальных клеток, выделенных из разных источников

Introduction. As an alternative to autochondral transplantation, variants of chondrocyte replacement with mesenchymal stromal cells (MSCs) were considered, since these cells are present in all organs and tissues of human body and possess multilinear potential for differentiation. A number of studies demonstrate that the ability for chondrogenic differentiation of MSCs from different tissues varies, however, those studies are few and controversial. In accordance with the ethical principles and the technical ease of obtaining, adipose tissue, Wharton’s jelly (stroma) and dental pulp are the most attractive sources of MSCs for tissue engineering.Aim: to compare the chondrogenic potential of MSCs allocated from adipose tissue, Wharton’s jelly of the umbilical cord, and human deciduous teeth pulp cultured in the composition of microspheres (pellets).Materials and methods. The phenotype of primary cultures of MSCs was studied via flow microscopy. Chondrogenic differentiation was performed with 3D-culture in microspheres in the presence of TGFβ1 for two weeks under standard conditions. Human chondroblasts were used as a positive control. Cell viability was determined by fluorescent staining. Morphological study was performed using histological and immunohistochemical staining methods.Results. Cultures of MSCs from all sources had similar phenotypes CD29+, CD34–, CD44+, CD49b+, CD45–, CD73+, CD90+, HLADR. In the mass of living cells in microspheres only singular dead cells were visualized. A significant production of extracellular matrix (ECM) was observed in the chondroblast and adipose tissue microspheres, whereas in the microspheres of dental pulp and umbilical cord stroma derived MSCs, no significant ECM was detected. Among the MSCs, the highest production of collagen and glycosaminoglycans (GAG) in the ECM was observed in the microspheres of adipose tissue-derived MSCs, and the lowest production – in the microspheres of dental pulp-derived MSCs. Conclusion. A histological analysis of all microspheres after 14 days of culturing in the chondrogenic medium revealed the signs of differentiation in the chondrogenic direction, a progressive increase of the ECM produced by cells, and the presence of total collagen and GAG in it. Of all the MSCs studied, the greatest chondrogenic potential in vitro (the intensity of development of ECM components) is possessed by the adipose tissue-derived MSCs.Введение. В качестве альтернативы аутохондротрансплантации рассматриваются варианты замены хондроцитов на мезенхимальные стромальные клетки (МСК), которые присутствуют во всех органах и тканях человеческого организма и обладают мультилинейным потенциалом дифференцировки. В ряде исследований показано, что способность к хондрогенной дифференцировке МСК из разных тканей различается, однако работы, посвященные данному вопросу, единичны и противоречивы. В соответствии с этическими принципами и технической простотой получения наиболее привлекательными для тканевой инженерии источниками МСК представляются жировая ткань, Вартонов студень пуповины (строма) и пульпа зуба.Целью настоящего исследования было сравнение хондрогенного потенциала МСК, выделенных из жировой ткани, Вартонова студня пуповины и пульпы молочного зуба человека, при культивировании в составе микросфер (пеллет).Материалы и методы. Фенотип первичных культур МСК исследовали методом проточной микроскопии. Хондрогенную дифференцировку проводили при 3D-культивировании в составе микросфер в присутствии TGFβ1 в течение двух недель при стандартных условиях. В качестве положительного контроля использовали хондробласты человека. Жизнеспособность клеток определяли методом флуоресцентного окрашивания. Морфологическое исследование проводили с использованием гистологических и иммуногистохимических методов окрашивания.Результаты. Культуры МСК из всех источников обладали сходным фенотипом CD29+, CD34–, CD44+, CD49b+, CD45–, CD73+, CD90+, HLADR. В составе микросфер визуализировались лишь единичные мертвые клетки в массе живых. Значительная продукция внеклеточного матрикса (ВКМ) отмечалась в микросферах из хондробластов и жировой ткани, тогда как в микросферах из МСК пульпы зуба и стромы пуповины выраженной наработки ВКМ не обнаружили. Среди МСК наибольшую наработку коллагена и гликозаминогликанов (ГАГ) в ВКМ наблюдали в микросферах из МСК жировой ткани, а наименьшую – в микросферах из МСК пульпы зуба.Заключение. Гистологический анализ всех микросфер через 14 суток культивирования в хондрогенной среде выявил признаки дифференцировки в хондрогенном направлении, прогрессивное увеличение продуцируемого клетками ВКМ и присутствие в нем общего коллагена и ГАГ. Из всех исследованных МСК наибольшим хондрогенным потенциалом in vitro (интенсивность наработки компонентов ВКМ) обладают МСК жировой ткани

Bioinformatics and molecular modeling in glycobiology

The field of glycobiology is concerned with the study of the structure, properties, and biological functions of the family of biomolecules called carbohydrates. Bioinformatics for glycobiology is a particularly challenging field, because carbohydrates exhibit a high structural diversity and their chains are often branched. Significant improvements in experimental analytical methods over recent years have led to a tremendous increase in the amount of carbohydrate structure data generated. Consequently, the availability of databases and tools to store, retrieve and analyze these data in an efficient way is of fundamental importance to progress in glycobiology. In this review, the various graphical representations and sequence formats of carbohydrates are introduced, and an overview of newly developed databases, the latest developments in sequence alignment and data mining, and tools to support experimental glycan analysis are presented. Finally, the field of structural glycoinformatics and molecular modeling of carbohydrates, glycoproteins, and protein–carbohydrate interaction are reviewed

STUDYING OF FUNCTIONAL CONDITION OF THE SMALL INTESTINE IN CHOLELITHIASIS

Aim. Complex research of the functional condition of the small intestine in different stages of cholelithiasis.Materials and methods. 47 patients with different stages of cholelithiasis were examined. There were 29 patients with the first (prestone) stage and 18 — with the second (stone) stage of cholelithiasis. In an assessment of the functional condition of the small intestine were used clinical data and results of the load tests by sugars. Cavitary digestion was studied by load test with polysaccharide (soluble starch), membrane digestion — with disaccharide (sucrose), absorption — with monosaccharide (glucose). Glucose level in blood was determined on an empty stomach, then after oral reception of 50g of glucose, sucrose or starch in 30, 60 and 120 minutes.Results. Researchers showed that in the most of patients with cholelithiasis there were disturbances in clinical and functional condition of the small intestine. In an assessment of the cavitary digestion the level of glycemia was authentically lowered by 43% in prestone stage and by 66% in stone stage of cholelithiasis in comparison with control. In an assessment of membrane digestion in patients with the stone stage of cholelithiasis the level of glycemia was lowered in comparison with group of control and with the prestone stage by 30% and 19% respectively.Conclusion. In prestone stage of cholelithiasis there were decrease of the cavitary digestion primary, and in stone stage of cholelithiasis — all stages of hydrolysis-resorptive process in the small intestine were disturbed

STUDY OF PHYSICO-CHEMICAL PROPERTIES OF BILE AFTER CHOLECYSTECTOMY ON CHOLELITHIASI S

The aim. To study the physico-chemical properties of hepatic bile and the state of lipid metabolism before and after cholecystectomy for cholelithiasis.Material and methods. 210 patients with stage I cholelithiasis (comparison group) and 90 patients who underwent cholecystectomy for stage II and III of the cholelithiasis (observation group) were examined. The groups were balanced by gender and age. In verification of the diagnosis, in addition to general clinical data, the results of ultrasound examination of the biliary system were used. A duodenal sounding was carried out followed by a macroscopic, microscopic examination of the hepatic portion of bile, determination of its physical properties and chemical composition. Lipid blood metabolism was studied with an estimate of the coefficient of atherogenicity.Results. With ultrasound of the biliary system, signs of biliary sludge were found in 86% of the comparison group patients, in 37% of the patients in the observation group there was an increase in the common bile duct. The study of the chemical composition of the hepatic bile of patients of both groups revealed an increase in cholesterol, total sialic acids and total protein, a decrease in bile acids, phospholipids, cholate-cholesterol and phospholipid-cholesterol coefficients. In the study of physical properties, a thickening of bile and an increase in its viscosity were established. Evaluation of the lipid spectrum of blood revealed that lipid metabolism disorders, which are present in patients with cholecystectomy, are preserved after cholecystectomy.The conclusion. After cholecystectomy for cholelithiasis, bile is still secreted prone to stone formation, as evidenced by its altered physic-chemical parameters. Рatients after cholecystectomy need to use preventive measures to prevent the formation of lithogenic bile