Study of tribological properties of human buccal epithelium cell membranes using probe microscopy

In this work demostrates a unique method for determining the absolute value of the friction force of a nanoobject on the surface of a cell membrane using atomic force microscopy. The tribological properties of membranes of adult human buccal epithelium cells in the presence of a protective adsorption buffer layer of ~ 100 nm on their surface were studied using atomic force microscopy in the contact scanning mode. Local mapping of the tribological characteristics of the surface was carried out, viz. friction FL = FL(x, y) and adhesion Fadh = Fadh(x, y) forces were measured. Studies of the friction force Ffr on the membrane surface at the nanolevel showed that its value varies discretely with an interval equal to lLF ≈ 100 nm. It was shown that such discreteness is determined by the interval lLF of the action of adhesive forces Fadh and indicates the fractal nature of the functional dependence of the friction force on the coordinate Ffr = Ffr(x). Thus, for nano-objects with dimensions ≤ lLF, the absolute value of Ffr decreases according to a power law with an increase in the size of the object, which contradicts the similar dependence of the friction force for macro-objects in the global approximation

Binding polynomial in molecular self-assembly

In the present work the concept of a binding polynomial is revisited for the most widely used case of self-assembly of identical molecular units and results in the re-construction of a link to the grand partition function of such a system. It is found that if the self-assembly process is not pronounced (i.e., the product of the equilibrium constant and the monomer concentration is close to zero), the binding polynomial has the meaning of a molecular partition function that is given by the summation over energy levels of any molecule in the system. In other cases the concept of a binding polynomial may be misleadin

Horizon-T Experiment Detailed Calibration of Cables

The ability to extract the pulse width and translate it into the actual disk width of the Extensive Air Showers (EAS) is a hard one requiring accurate knowledge of the system performance. For that, the analysis for the cable calibration for Horizon-10T detectors has been re-analyzed in a different form that allows for better signal width measurements. An innovative detector system Horizon-10T, constructed to study EAS in the energy range above 1016 eV coming from a wide range of zenith angles (0o - 85o), is located at Tien Shan high-altitude Science Station of Lebedev Physical Institute of the Russian Academy of Sciences at approximately 3340 meters above the sea level.Comment: in-depth analysis of cable calibration for 'new' cables only v2 corrects minor typo

Antibacterial properties of PMMA functionalized with CuFe2O4/Cu2O/CuO nanoparticles

We have prepared a composite thin coating by incorporation of CuFe2O4/Cu2O/CuO nanoparticles in polymethyl methacrylate (PMMA) matrix by using the solution casting method. The electrical explosion of two twisted wires (EETW) was used to obtain multicomponent CuFe2O4/Cu2O/CuO nanoparticles with an average particle size of 20–70 nm. The microscopic studies showed that the nanoparticles in the composite coatings are evenly distributed. However, nanoparticles are strongly agglomerated as the powder concentration in the coating increases to 5 wt.% and 10 wt.%, as the size of particle agglomerates increases to 50 and 100 µm, respectively. Therefore, nanoparticles were pre-treated with ultrasound when introduced into the PMMA matrix. The thermal stability of the composite coating does not change with the introduction of CuFe2O4/Cu2O/CuO nanoparticles in the amount of 5 wt.%. The inclusion of nanoparticles in the PMMA matrix significantly enhances its antibacterial activity. The addition of 5 wt.% nanoparticles inhibited the growth of E. coli by 100% and the growth of MRSA by 99.94% compared to pure PMMA already after 3 h of exposure of bacteria on the surface of the composites. This research provides an easy-to-manufacture and cost-efficient method for producing a uFe2O4/Cu2O/CuO/PMMA composite coating with a broad application as an antibacterial material

Fractal C60 fullerene aggregation: Equilibrium thermodynamics approach

Using dynamic light scattering (DLS) data we showed that the main physico-chemical parameters characterizing C60 fullerene aggregation in solution, viz. equilibrium aggregation constant and fractal number, may be obtained from equilibrium thermodynamics approac

Post-COVID immunopatology syndrome: characteristics of phenotypical changes in the immune system in post-COVID patients

This study examines the long-term effects of SARS-CoV-2 infection on immune status. Given the prolonged and profound immune dysregulation observed during acute SARS-CoV-2 infection, it remains to be determined whether these changes translate into subsequent immune system dysfunction in recovering individuals. In this sense, the aim of the study was to study the parameters of the immune system in patients who had undergone SARS-CoV-2 infection. 150 patients who underwent SARS-CoV-2 infection were examined according to 96 parameters using flow cytometry. A complete blood count was performed using a Medonic device (Sweden); ELISA method determined the levels of general and specific IgM, IgG, IgA, compliment fragments (JSC Vector-Best, Russia). The activity of the phagocytes was studied according to the generally accepted method. The study found that at least four phenotypes of immune system disorders are detected in patients. The first two phenotypes are related to the impairment of innate immune system factors and are associated with a decrease in the number of CD46+ and NK cells. It has been observed that a decrease in CD46+ persists for a long time in a significant number of recovered patients, highlighted by the impaired expression of this marker in various subpopulations of lymphocytes. The decrease in the level of natural killers was accompanied by a compensatory increase in the number of T lymphocytes, mainly due to T helpers and TNK lymphocytes, and the growth of total memory B cells. Two other identified phenotypes are characterized by damage to acquired immune response factors and are associated with damage to B cells and T cytotoxic cells. The relationship of such disorders with damage to hematopoiesis erythrocyte and platelet sprouts, which contribute to the appearance of hypoxia and possible violation of the blood coagulation system, has been shown. Therefore, the results obtained indicate a long-term pronounced damage to the immune system in postCOVID patients that requires immunocorrection of these disorders

Колебательная, релаксационная и трансляционная подвижность ионов Li+ в монокристалле LiNbGeO5.

Dielectric properties of single crystals of LiNbGeO5, crystallizing in the andalusite (β-Al2SiO5) structure, have been studied. Dielectric and conducting properties along the major crystallographic axes were investigated at frequencies from 1 to 1000 kHz and in the range of temperatures between 100 and 600 K. Determined potential barriers between the equilibrium positions of Li+ ions are classified as low energy (0.23-0.79 eV, along the a axis) and high energy (0.9-1.90 eV, along the a, b, and c axes). Additional interstitial sites with the distances between them 0.3-0.4 Å have been found along the a axis, while no such sites observed along the b and c axes. Activation energy (Ea) in the direction a is 0.47 eV and ?a(570 K) = 2.10-5 S/cm, which correspond to the super-ionic conductivity.Исследованы диэлектрические свойства монокристаллов LiNbGeO5 со структурой минерала андалузита (β-Al2SiO5). Диэлектрические и проводящие свойства изучены вдоль главных кристаллографических осей a, b, c при частоте измерительного поля 1-1000 кГц в интервале температур 100-600 К. Найденные значения потенциальных барьеров между положениями равновесия ионов Li+ подразделяются на низкоэнергетические (0.23-0.79 эВ, a-ось) и высокоэнергетические (0.9-1.80 эВ, a, b и c-оси). В направлении оси a обнаружены дополнительные междуузельные позиции с расстояниями между ними 0.3-0.4 A, в то время как для осей b и c такие позиции отсутствуют. В направлении a энергия активации Еa = 0.47 эВ и значение ?a(570 К) = 2.10-5 См/см, что соответствует суперионной проводимости

Phase formation and relaxor properties of lead-free perovskite ceramics on the base of sodium-bismuth titanate

The work was supported by the Russian Foundation for Basic Research (Projects 16-53-48009, 17-03-00542)

Effects of boundary conditions on magnetization switching in kinetic Ising models of nanoscale ferromagnets

Magnetization switching in highly anisotropic single-domain ferromagnets has been previously shown to be qualitatively described by the droplet theory of metastable decay and simulations of two-dimensional kinetic Ising systems with periodic boundary conditions. In this article we consider the effects of boundary conditions on the switching phenomena. A rich range of behaviors is predicted by droplet theory: the specific mechanism by which switching occurs depends on the structure of the boundary, the particle size, the temperature, and the strength of the applied field. The theory predicts the existence of a peak in the switching field as a function of system size in both systems with periodic boundary conditions and in systems with boundaries. The size of the peak is strongly dependent on the boundary effects. It is generally reduced by open boundary conditions, and in some cases it disappears if the boundaries are too favorable towards nucleation. However, we also demonstrate conditions under which the peak remains discernible. This peak arises as a purely dynamic effect and is not related to the possible existence of multiple domains. We illustrate the predictions of droplet theory by Monte Carlo simulations of two-dimensional Ising systems with various system shapes and boundary conditions.Comment: RevTex, 48 pages, 13 figure

Предварительная оценка выведения 225Ac у пациентов, проходящих радионуклидную терапию с 225Ac-DOTA-TATE

The aim of this study was to evaluate the activity of 225Ac in urine of patients undergoing radionuclide therapy with 225Ac-DOTA-TATE. Activity concentration was determined in the urine samples collected within 72 hours after injection of 225Ac-DOTA-TATE, using the ORTEC semiconductor gamma spectrometer, model TSP-DX-100T-PAC-PKG-1. Calculation of excreted activities was additionally performed based on scintig- raphy scans of patients receiving 225Ac-DOTA-TATE. Scans were conducted 5 times for each patient: immedi- ately after injection, at 4 hours, and on the 1st, 2nd, and 3rd days after injection of the radiopharmaceutical. Absolute activity values and fractions of the injected activity were calculated based on the specific activity values. The results of the calculated activity concentration values demonstrate that maximum excretion was observed within the four hours after 225Ac-DOTA-TATE injection. Significant differences between the two methods of determining 225Ac activity were observed only on the third day after radiopharmaceutical injection, which allows for the simplification of future experimental work by using indirect radioactivity measurement methods for activity calculations. There were no significant differences between patient groups with different number of 225Ac-DOTA-TATE injection, which allows for the exclusion of this parameter in the evaluation of experimental results. The results of this study represent the first published experimental data on the determi- nation of actinium excretion in patients.Целью данной работы является оценка активности 225Ac в моче пациентов, проходивших радионуклидную терапию с 225Ac-DOTA-TATE. Удельная активность определялась в пробах мочи, которые отбирались в срок до 72 ч после введения 225Ac-DOTA-TATE с использованием полупроводникового гамма-спектрометра ORTEC, модели TSP-DX-100T-PAC-PKG-1. Также производился расчет выводимых активностей на основании сцинтиграфии пациентов, сканирование осуществляли 5 раз для каждого пациента: сразу после введения, через 4 ч, 1, 2, 3 сут после введения препарата. На основании значений удельных активностей рассчитывались абсолютные значения активностей и проценты от введенной активности. Результаты рассчитанных значений удельных активностей демонстрируют, что максимум выведения наблюдается в первые 4 ч после введения препарата. Статистически значимые различия между 2 методами определения активности 225Ac наблюдались только для 3-х суток после введения препарата, что позволяет в дальнейшем упростить проведение экспериментальных работ, используя методы непрямой радиометрии для расчета активности. Между группами пациентов с разным числом ранее проведенных введений радиофармацевтических лекарственных препаратов отсутствуют статистически значимые различия, что позволяет в дальнейшем не учитывать номер эпизода радионуклидной терапии при оценке результатов экспериментальных работ. Результаты работы являются первыми опубликованными экспериментальными данными по определению выведения 225Ac-DOTA-TATE у пациентов