ВПЛИВ НЕІДЕАЛЬНОГО ТЕПЛОВОГО КОНТАКТУ НА ТЕПЛООБМІН В СИСТЕМІ БАГАТОШАРОВИХ ЦИЛІНДРИЧНИХ ТІЛ

Introduction. Solving the problem of heat transfer in multilayer structures devoted a large number of works. The vast majority of them are limited to the case of perfect thermal contact between the layers. However, according to the authors, the problems of thermal conductivity in multilayer structures using into account the imperfect thermal contact are insufficiently studied. The number of such studies is quite limited. Also, known studies are usually limited to two layers. That is because the increase in the number of layers (given the choice of methods of practical implementation) leads to several computational difficulties. Therefore, the problem of constructing an effective analytical scheme for the study of heat transfer processes in multilayer structures in the presence of imperfect thermal contact between the layers remains an urgent task.Purpose. Application of the direct method to the study of heat transfer processes in the system "continuous cylinder inside a multilayer cylindrical shell" with imperfect thermal contact.Methods. An auxiliary problem set for the distribution of the temperature field in a multilayer solid cylindrical hollow body (a cylinder of the sufficiently small radius is "removed") taking into account the imperfect thermal contact between the individual layers. According to the already known scheme of the direct method solve this problem.Results. Boundary transition obtained the solution of the original problem. Boundary transition: the radius of the"removed" cylinder, with the centre at the origin, goes to zero. This approach established that the solution to the problemis limited in the whole structure. In this case, the solution obtained explicit formulas.Conclusions. Effective analytical scheme constructed for application of the direct method to the study of heattransfer processes in multilayer hard cylindrical solids taking into account the non-ideal thermal contact between thelayers. The number of layers, their size and arrangement are considered arbitrary.Проблема. Розв’язуванню проблеми теплообміну в багатошарових конструкціях присвячено численний ряд робіт. Переважна більшість з них обмежується випадком ідеального теплового контакту між шарами. Проте, на думку авторів, недостатньо вивченими є задачі теплопровідності в багатошарових конструкціях з урахуванням неідеального теплового контакту. Кількість таких досліджень є достатньо обмеженою. Крім цього, відомі дослідження, як правило, обмежуються двома шарами. Це зумовлено тим фактором, що збільшення кількості шарів (з огляду на вибір методів практичної реалізації) призводить до певних обчислювальних труднощів. Тому, проблема побудови ефективної аналітичної схеми дослідження процесів теплообміну в багатошарових конструкціях за наявності неідеального теплового контакту між шарами залишається актуальною задачею.Мета. Застосування прямого методу до дослідження процесів теплообміну в системі «суцільний циліндр всередині багатошарової циліндричної оболонки» при неідеальному тепловому контакті.Методи дослідження. Ставиться допоміжна задача про розподіл температурного поля у багатошаровому твердому циліндричному порожнистому тілі («вилучено» циліндр достатньо малого радіуса) з урахуванням неідеального теплового контакту між окремими шарами. Ця задача розв’язується за вже відомою схемою прямого методу.Основні результати дослідження. Розв’язок вихідної задачі отримано шляхом граничного переходу: радіус «вилученого» циліндра, з центром в початку координат, спрямовується до нуля. Встановлено, що при такому підході, розв’язок поставленої задачі обмежений у всій конструкції. При цьому для розв’язку отримано явні формули.Висновки. Побудована ефективна аналітична схема застосування прямого методу до дослідження про-цесів теплообміну в багатошарових суцільних циліндричних твердих тілах з урахуванням неідеального теплового контакту між шарами. При цьому кількість шарів, їх розміри та порядок розташування вважаються довільним

Language transformation in social networks under the influence of the war: analysis of dynamics and its context

Стаття досліджує динаміку зміни мови у соціальних мережах під часвеликого конфлікту, зокрема під час війни. З'ясовано, що користувачі віддають перевагу українській та англійській мовам, уникаючи російську, у зв'язку з національною ідентичністю, безпекою та стратегічними перевагами. Результати вказують на складну взаємодію мовних вподобань та геополітичних реалій під час військових подійThe article examines the dynamics of language change in social networks during major conflicts, particularly during war. It has been found that users prefer Ukrainian and English languages, avoiding Russian, due to national identity, security, and strategic advantages. The results indicate a complex interplay between linguistic preferences and geopolitical realities during military event

Dynamics of the usage of "війна" and "war" in social media influenced by military events: psychological and social adaptation of ukrainian society

Дослідження спрямоване на аналіз зміни активності користувачів соціальних мереж під впливом воєнних подій. Використовуючи дані з Instagram, досліджено згадування слів «війна» або «war» серед топ-100 найвідоміших українців до і після початку конфлікту. Результати свідчать про значну зміну у спілкуванні, що відображає психологічну та соціальну реакцію суспільства на кризові ситуаціїThe study aims to analyze the change in social media user activity influenced by military events. Utilizing data from Instagram, mentions of the words "війна" or "war" among the top 100 the most famous Ukrainians before and after the conflict outbreak were examined. The results indicate a significant shift in communication, reflecting the psychological and social response of society to crisis situation

Методика інженерних розрахунків біореакторів для біологічного очищення природних і доочищення стічних вод

Relevance of research. For the first time  raised the question of the expediency of microbiological methods for purification of natural waters, Professor P.I. Gvozdiak, who claims that the microbiological method can clean any contaminated water, significantly improve the efficiency of water purification, improve the quality of purified water and reduce its cost. With the biological method of neutralizing, the specific Gallonella ferruginea iron bacteria, due to their catalytic action, quickly oxidize Fe2+, and the resulting iron hydroxide Fe(OH)3 accumulate in a compact form, which significantly increases the dirt of contact clarifying filters (CСF) and the duration of the filtration cycle. Principle of BR work. Microorganisms inhabiting a biofilm, which is formed on the surface of filaments of fibrous fluid, oxidize substances that are in the source water, oxygen in the air, while receiving energy for their livelihoods. After intense aeration, the initial water enters the BR and is evenly distributed between the threads of the fibrous boom, flowing over the surface on which the biofilm is formed with aerobic microorganisms. At the same time, processes such as adhesion, sorption, diffusion, destruction, oxidation, etc. occur, which results in the rapid removal of oxidizing substances and the formation of new substances. BR has the following functions: -  biochemical oxidation of impurities present in the source water; - removal of gases from the water to eliminate bubble colmatation in the subfilter space of the CCF; - ensuring a constant rate of water filtration during the filtration cycle due to an increase in the water level in it by changing the pressure loss on the CCF from         hf.0 (at a clean loading) to hf.max (at the end of the filtration cycle). Mathematical model and algorithm of engineering calculations BR. For a mathematical description of the processes of water purification in the BR, it is necessary to establish the balance of the change in the concentration of contamination in the biofilm, the liquid film and the volume of the source water, which is located between the fibrous threads and moves from top to bottom. BR perform the role of air separators, the area of which must be taken from the calculation of the velocity of the downstream water flow not more than 0,05 m/s and the duration of water in it for at least 1 minute. Engineering calculations lead in the following sequence: - for the estimated flow of water through the BR Qe, m3/h, the accepted number of threads of the fibrous load N and the cross-sectional area of one thread, determine the cross-sectional area of the BR and the velocity of water flow in the BR; - to ensure the required time for water in the BR with a duration of te≥1 min at the limit velocity of water in the BR Vl = 0,05 m/s its height should be not less than He.min≥3 m; - for preliminary calculations, we take the estimated values of the output constants and coefficients defined in the special literature: Kc = 0,025 - 0,080 m/h;     A = 0,01 – 0,04 m/h; δp = 0,1 – 0,2 mm; - according to laboratory studies, we find the maximum specific bristle content of BR, the duration of the filtracycle in the zone of accumulation of contaminants and the duration of washing BR in its given intensity; - specify the estimated values of Hb and Cf and the efficiency of water purification in the BR. Conclusions. The required working height of the loading BR depends on the depth of the water treatment C0 / Сf, is directly proportional to the water filtration rate Vf  and inversely proportional to the number of threads in the unit of loading БР. The developed methodology of engineering calculations BR can determine their rational design and technological parameters, based on the requirements of providing the required time for water in the BR at the marginal velocity of the downward movement of water and the calculated efficiency of water purification from impurities.Проаналізовано систему біологічного очищення води з різними домішками в ній при прямоточному русі води через послідовно взаємодіючі споруди: біореактор (БР) – контактний прояснювальний фільтр (КПФ). Розроблена методика інженерних розрахунків БР для забезпечення процесів насичення води киснем, видалення з води газів та біохімічного окиснення домішок, що перебувають у вихідній воді, за допомогою мікроорганізмів, іммобілізованих на волокнистому фільтрувальному завантаженні

Development new radiopharmaceutical based on 5-thio-d- glucose labeled technetium-99m

The article considers the obtaining and possibility of using 5-thio-D-glucose labeled technetium-99m for the diagnosis of malignant tumors by single photon emission computed tomography. The analysis of the level of international developments of radiopharmaceuticals based on derivatives of glucose has been carried out. Also the article provides information on of using experimental batches of lyophilisate on the basis of 5-thio-D-glucose for preliminary biomedical testing on the mice

Experimental study of radiopharmaceuticals based on technetium-99m labeled derivative of glucose for tumor diagnosis

Purpose: to study the potential utility of 1-thio-D-glucose labeled with 99mTc for cancer imaging in laboratory animals. Materials and method: the study was carried out in cell cultures of normal CHO (Chinese hamster ovary cells CHO) and malignant tissues MCF-7 (human breast adenocarcinoma MCF-7). To evaluate the uptake of 99mTc-1-thio-D-glucose in normal and tumor tissue cells, 25 MBq of 1-thio-D-glucose labeled with 99mTc was added to the vials with 3 million cells and incubated for 30 minutes at room temperature. After centrifugation of the vials with cells, the supernatant was removed. Radioactivity in vials with normal and tumor cells was then measured. In addition, the study included 40 mice of C57B 1/6j lines with tumor lesion of the right femur. For neoplastic lesions, Lewis lung carcinoma model was used. Following anesthesia, mice were injected intravenously with 25MBq of 99mTc-1-thio-D-glucose. Planar scintigraphy was performed 15 minutes later in a matrix of 512x512 pixels for 5 minutes. Results: when measuring the radioactivity of normal and malignant cells after incubation with 99mTc-1-thio-D- glucose, it was found that the radioactivity of malignant cells was higher than that of normal cells. The mean values of radioactivity levels in normal and malignant cells were 0.3±0.15MBq and 1.07±0.6MBq, respectively. All examined animals had increased accumulation of 99mTc-1-thio- D-glucose at the tumor site. The accumulation of 99mTc-1-thio-D-glucose in the tumor was on average twice as high as compared to the symmetric region. Conclusion: The present study demonstrated that 99mTc-1-thio-D-glucose is a prospective radiopharmaceutical for cancer visualization. In addition, high accumulation of 99mTc-1-thio-D-glucose in the culture of cancer cells and in tumor tissue of animals demonstrates tumor tropism of the radiopharmaceutical

Pancreatic β-cell imaging in humans: Fiction or option?

Diabetes mellitus is a growing worldwide epidemic disease, currently affecting 1 in 12 adults. Treatment of disease complications typically consumes ∼10% of healthcare budgets in developed societies. Whilst immune‐mediated destruction of insulin‐secreting pancreatic β cells is responsible for Type 1 diabetes, both the loss and dysfunction of these cells underly the more prevalent Type 2 diabetes. The establishment of robust drug development programmes aimed at β‐cell restoration is still hampered by the absence of means to measure β‐cell mass prospectively in vivo, an approach which would provide new opportunities for understanding disease mechanisms and ultimately assigning personalized treatments. In the present review, we describe the progress towards this goal achieved by the Innovative Medicines Initiative in Diabetes, a collaborative public–private consortium supported by the European Commission and by dedicated resources of pharmaceutical companies. We compare several of the available imaging methods and molecular targets and provide suggestions as to the likeliest to lead to tractable approaches. Furthermore, we discuss the simultaneous development of animal models that can be used to measure subtle changes in β‐cell mass, a prerequisite for validating the clinical potential of the different imaging tracers