Numerical Analysis of Liquid Menisci in the EFG Technique

This chapter is devoted to the analysis of the behavior of the profile curves of the melt menisci for the sapphire crystal growth by edge-defined film-fed growth (EFG) technique. The menisci of the shaped crystals with capillary channels, fibers, and tubes (including cases of outer and inner circular menisci) are considered. Also, we investigated the profile curves of menisci both in the cases of the positive and negative angles between profile curve and the working edge of the die. The cases of outer and inner circular menisci of the tubular crystals and menisci at capillaries and fibers are considered

Mathematical model for investigation of alkylbenzenes sulfonation

The relevance. Lack of experimental data that allow developing a scientifically based method for calculating and designing film-type reactors, which are also used to produce alkylbenzenesulfonic acids. These acids, in their turn, are currently the main components of synthetic detergents. The issue of increasing reactor equipment efficiency can be most effectively solved using mathematical models built on a physical and chemical basis. The aim. Development of a mathematical model of alkylbenzenes sulfonation, taking into account a substance mass transfer from a gas phase to a liquid phase. Software implementation of the developed model, as well as the use of the developed mathematical model for studying the influence of the process parameters on its efficiency. Object. Alkylbenzenes sulfonation with sulfuric anhydride in a multitube film reactor. Methods. Mathematical modeling is used to perform all computational operations, a modern high-level general-purpose programming language with automatic memory management is used. The quantum-chemical methods for determining thermodynamic parameters of chemical reactions were used. Results. The paper considers the principles of constructing a mathematical model of sulfonation. The authors have developed the calculation program in the Python programming language and assessed the accuracy of description of a real process and the influence of the system technological parameters on a product yield and quality, taking into account a substance interfacial transfer. The system of practical recommendations for improving the alkylbenzenes sulfonation resource efficiency was developed. The mathematical model adequately describes the process. The calculated data are compared with the real data from the operating unit for alkylbenzenes sulfonation with sulfuric anhydride

Analysis of kinematic and kinetic parameters of pace in cerebral palsy patients with internal torsion hip deformity

Literature data on the correlation between femoral torsion during clinical examination and during walking are different. Aim of the study was to compare kinetics and kinematics in cerebral palsy patients with iatrogenic crouch gait pattern with and without clinically diagnosed internal femoral torsion. Material and methods. Comparative analysis of clinical examination and three-dimensional gait analysis (3DGA) was performed in 61 subjects (122 limbs), GMFCS II with iatrogenic crouch gait pattern. The average age was 14.5 ± 2.5 years. This sample was formed in 2018–2021. Kinetic and kinematic data were recorded by Qualisys 7+ optical cameras (8 cameras) with passive marker video capture technology, synchronized with six KISTLER dyno platforms (Switzerland). The analysis was performed in the QTM (Qualisys) and Visual3D (C-Motion) programs with automated calculation of values. Based on the clinical data, all the patients were divided as follows: I – no clinically detected internal femoral torsion – 50 limbs, II – clinically detected internal femoral torsion – 68 limbs. Results. Comparison of the values of kinematics and kinetics in groups of patients according to the criterion of clinically detected/not detected had statistically significant differences in kinematics – the maximum and minimum values of femur and tibia torsion relative to the norm. Differential diagnosis of compensated/decompensated internal femoral torsion was represented by multidirectional values of the angle of foot positioning relative to the motion vector. The kinetic parameters in the groups were statistically doubtful, because they depended on the walking speed of patients, their ability to move. Conclusions. The values of maximum femoral torsion angle up to 22° were not clinically interpreted as internal femoral torsion, those from 22° to 28° can be interpreted both with clinically revealed femoral torsion (68 %) and with the absence of femoral torsion (22 %), which corresponds to the risk group, those more than 28° fell into the group of clinically diagnosed internal femoral torsion

In vitro terahertz spectroscopy of malignant brain gliomas embedded in gelatin slab

In our work, we have performed in vitro terahert

In vitro terahertz spectroscopy of gelatin-embedded human brain tumors - a pilot study

We have performed the in vitro terahertz (THz) spectroscopy of human brain tumors. In order to x tissue

Резолюция Совета экспертов от 20 мая 2023 г. «Вопросы безопасности лечения ревматологического пациента»

At the meeting of the Expert Council on May 20, the safety of treatment for patients with osteoarthritis (OA), the most common form of joint disease, was discussed. The first step in the treatment of OA should be the administration of symptomatic delayed-acting agents (SYSADOA) and nonsteroidal anti-inflammatory drugs (NSAIDs). However, given the current understanding of the pathogenesis of inflammation, as well as the fact that it is an active process involving multiple proinflammatory and pro-resolving mediators, it is reasonable to limit the cyclooxygenase-2 suppressive treatment and to include medications with multipurpose effects that contribute to the resolution of inflammation, in particular Zeel® T and Traumeel® S. Traumeel® S affects all stages of inflammation, mostly on the pro-resolving mediators synthesis, and Zeel® T affects chondrogenesis, inflammation, metabolic processes in cartilage tissue and prevents angiogenesis.It was found that it is advisable to use Traumeel® S when it is not possible to prescribe systemic NSAIDs for pain relief. The combination of the proven therapeutic efficacy of Zeel® T and Traumeel® S with a minimal number of adverse events and the absence of interactions with other drugs allows them to be used as an independent treatment regimen for OA.На заседании Совета экспертов 20 мая 2023 г. были рассмотрены вопросы безопасности лечения пациентов с остеоартритом (ОА) — самой распространенной формой заболеваний суставов. Первым шагом терапии ОА должно быть назначение симптоматических средств замедленного действия (SYSADOA) и нестероидных противовоспалительных препаратов (НПВП). Однако, учитывая современные представления о патогенезе воспаления, а также то, что это активный процесс с участием большого числа провоспалительных и проразрешающих медиаторов, представляется актуальной тактика ограничения терапии с подавлением циклооксигеназы 2 и включения в схемы лечения лекарственных средств с многоцелевым действием, способствующих разрешению воспаления, в частности препаратов Цель® Т и Траумель® С. Траумель® С оказывает воздействие на все этапы воспаления, в большей степени на синтез проразрешающих медиаторов, а Цель® Т влияет на хондрогенез, воспаление, метаболические процессы в хрящевой ткани и предотвращает ангиогенез.Отмечено, что при невозможности назначения системных НПВП для купирования боли целесообразно применение препарата Траумель® С. Сочетание доказанной терапевтической эффективности препаратов Цель® Т и Траумель® С с минимальным числом нежелательных явлений и отсутствием взаимодействий с другими лекарственными средствами позволяет использовать их как самостоятельную схему терапии при ОА

Formation of macrophage phenotupe in inflammatory and fibrogenic response: The role of mevalonate pathway and nuclear receptors LXR

Free cholesterol (Ch) and its oxidative derivatives, oxysterols (OS), are often accumulated in macrophages during chronic inflammation and atherogenesis. The effects of Ch and OS on the balance of pro- and anti-inflammatory cytokines in inflammatory response and the role of mevalonate pathway in the effects of these sterols are studied poorly. Both Ch and OS are able to affect mevalonate pathway activity and activity of nuclear hormonal receptors LXR. However the roles of LXR and mevalonate pathway in Ch and OS effects on macrophage polarization are unknown. We studied the effects of Ch, OS, atorvastatin, and mevalonic acid on the LPS-induced TNF-α, IL-10 and TGF-β1 production in macrophage cell culture. The study was carried out in murine peritoneal macrophages preincubated for 4 h with Ch (5 μg/mL), 25-hydroxycholesterol (25-OH-Ch) (5 μg/mL), 7-keto-Ch (5 μg/mL), farnesol (10 μM), or atorvastatin (5 μmol/mL) in the presence or absence of 1 mM of mevalonate. The cells were further incubated in the presence or absence of E. coli 0111:B4 lipopolysaccharide (LPS) for 24 h, and cytokine concentrations in incubation media were determined. Macrophages preincubation with Ch, 25-OH-Ch, or atorvastatin decreased LPS-induced TNF-α production in cell cultures, while supplementation of preincubation medium with mevalonic acid abrogated the effects of atorvastatin and Ch. The Ch, 25-OH-Ch, 7-keto-Ch and atorvastatin significantly reduced IL-10 production by LPS–stimulated macrophages, while farnesol had no effect. Supplementation of Ch or atorvastatin-containing preincubation medium with mevalonate restored IL-10 production. The TGF-β1 production was significantly enhanced by the presence of Ch or atorvastatin in preincubation medium as compared to the control level in non-treated macrophages, while 25-OH-Ch or farnesol decreased profoundly TGF-β1 production. Mevalonate abrogated the effect of Ch or atorvastatin but not of 25-OH-Ch or farnesol. These results allow to conclude, that the presence of Ch in micro-environment of inflammatory macrophages promotes anti-inflammatory and fibrogenic macrophage response; the latter is connected, at least in part, with the deficiency of mevalonate pathway intermediates, particularly to the deficiency of farnesol. At the same time hydroxysterols suppress both pro- and anti-inflammatory macrophage response independently of the impact of these compounds on mevalonate pathway. Apparently, pharmacological interference in the process of farnesylation could be a new approach to the control of chronic inflammation, including atherogenesis

UNSTEADY-STATE SIMULATION OF GASOLINE FRACTION PYROLYSIS

The relevance of the research is caused by the need of alkenes production increase as well as deepening understanding of the coke formation. The direction of petrochemical complex development and increase of pyrolysis efficiency is resources-saving, minimizing the volume of operations cost and the probability of occurrence of accidents. The main aim of the research is to develop a mathematical model for gasoline fraction pyrolysis, which will consider coke formation and its effect on the kinetic, hydrodynamic and thermodynamic components of the process. Object of the research is gasoline fraction pyrolysis process; dynamic of hydrocarbon stream composition during the process and coke formation side process. Methods. The methodological basis of the research is the system analysis and the method of mathematical modeling. In addition, quantum-chemical methods are used to calculate the thermodynamic and kinetic parameters of target and side chemical reactions occurring during the processing of hydrocarbon raw materials, and electron-structural methods based on the density functional theory; methods of computational fluid dynamics for the study of flow regimes and the deposition of coke particles on the walls of the coil; developed experimental methods for determining the optimal consumption of hydrocarbon raw materials and steam, predicting the duration of the inter-regeneration cycle of the pyrolysis furnace. Results. A non-stationary model of gasoline fraction pyrolysis was created to describe the coking side process along the length of the pyrolysis tube and over time. With the model, the rate of coke layer formation was calculated considering the technological parameters and the composition of feedstock. The calculated rate is 3,12∙10–7 mm per second. The results also made it possible to obtain the thickness distribution of the coke layer in the radiant coil, which indicates the acceleration of side processes towards the end of the process. This is due to formation of a significant amount of unsaturated compounds. It was found that changing the main parameters has two opposite effects. Thus, with an increase in temperature and pressure, both the yields of target products and the growth rate of the coke layer increased. An increase in the consumption of raw materials leads to a decrease in both of these parameters

Terahertz solid immersion microscopy for sub-wavelength-resolution imaging of biological objects and tissues

We have developed a method of terahertz (THz) solid immersion microscopy for imaging of biological objects and tissues. It relies on the solid immersion lens (SIL) employing the THz beam focusing into the evanescent-field volume and allowing strong reduction in the dimensions of the THz beam caustic. By solving the problems of the sample handling at the focal plane and raster scanning of its surface with the focused THz beam, the THz SIL microscopy has been adapted for imaging of soft tissues. We have assembled an experimental setup based on a backward-wave oscillator, as a continuous-wave source operating at the wavelength of λ = 500 μm, and a Golay cell, as a detector of the THz wave intensity. By imaging of the razor blade, we have demonstrated advanced 0.2λ-resolution of the proposed THz SIL configuration. Using the experimental setup, we have performed THz imaging of a mint leaf revealing its sub-wavelength features. The observed results highlight a potential of the THz SIL microscopy in biomedical applications of THz science and technology