Optimal Control Problem for Non-linear Degenerate Parabolic Variation Inequality: Solvability and Attainability Issues

We investigate the optimal control problem with respect to coefficients of the degenerate parabolic variational inequality. Since problems of this type can have the Lavrentieff effect, we consider the optimal control problem in a class of so-called Hadmissible solutions. We substantiate the attainability of H-optimal pairs via optimal solutions of some nondegenerate perturbed optimal control problems

Metabolic and cardiovascular features of the course of type 2 diabetes mellitus in men with hypogonadism

Introduction. Androgenic deficiency is an important pathogenetic element in the development of metabolic syndrome and cardiovascular diseases in men. It has been proven that in male patients with type 2 diabetes, hypogonadism develops much more often. Objective – to study the metabolic and cardiovascular features of the course of type 2 diabetes mellitus (T2DM) in men with androgen deficiency.Materials and methods. The study included 124 men with type 2 diabetes. To diagnose hypogonadism, the levels of total testosterone (T), sex hormone binding globulin (SHBG), albumin and luteinizing hormone (LH) were measured. Free testosterone (free T) levels were calculated using a calculator from Ghent University Hospital, Belgium. A retrospective analysis of case histories was carried out (spectrum of late complications, the presence of heart attacks and strokes, laboratory data – total cholesterol (CS), triglycerides (TG), fasting blood plasma glucose, basal insulin level, glycated hemoglobin (HbA1c)). The HOMA-IR index was used to determine the degree of insulin resistance.Results. The average age of men was 57.39 ± 9.41 years. The incidence of laboratory-confirmed hypogonadism is 50.81%. An average positive correlation was found between androgen deficiency and the incidence of non-fatal cardiovascular events (r = 0.45, p < 0.05). There was no statistically significant relationship between the presence of hypogonadism and the incidence and degree of late complications of T2DM. Patients with low T levels tended to have higher HOMA-IR values compared to patients with normal T levels (p < 0.05). At the same time, the indicators of carbohydrate and lipid metabolism did not differ significantly in these groups (p > 0.05).Conclusions. The revealed incidence of hypogonadism in men with T2DM corresponds to the data of international studies. The presence of a significant correlation between low testosterone levels and cardiovascular events in patients with T2DM suggests that hypogonadism can be used as an additional criterion for cardiovascular risk. Testosterone deficiency exacerbates insulin resistance, which can lead to weight gain and impair carbohydrate metabolism

Optimal Control Problem for Non-linear Degenerate Parabolic Variation Inequality: Solvability and Attainability Issues

We investigate the optimal control problem with respect to coefficients of the degenerate parabolic variational inequality. Since problems of this type can have the Lavrentieff effect, we consider the optimal control problem in a class of so-called Hadmissible solutions. We substantiate the attainability of H-optimal pairs via optimal solutions of some nondegenerate perturbed optimal control problems

Approaches to Assessing the Safety of Medicines during the COVID-19 Pandemic Using the Example of Azithromycin

Most of the medicines used to treat the novel coronavirus infection (COVID-19) are either approved under an accelerated procedure or not approved for the indication. Consequently, their safety requires special attention.The aim of the study was to review methodological approaches to collecting data on the safety of medicines, using COVID-19 treatment regimens involving azithromycin as a case study.Materials and methods: PubMed® (MEDLINE), Scopus, eLIBRARY, and Cyberleninka databases were searched for publications on azithromycin as part of combination therapy for COVID-19 in 2020–2021. Search queries included names of the medicinal product or its pharmacotherapeutic group and words describing adverse drug reactions (ADRs) during treatment.Results: the analysis included 7 publications presenting the results of studies covering the use of azithromycin as part of COVID-19 combination therapy in more than 4000 patients. Most commonly, the patients receiving COVID-19 therapy including azithromycin developed cardiovascular ADRs (up to 30% of azithromycin prescription cases). In 3 of the analysed publications, safety information was collected through spontaneous reporting and active identification based on the findings of laboratory and instrumental investigations performed during the clinical studies; in other 3, only spontaneous reports were used; and in the last one, ADR database information was studied.Conclusion: currently, information on ADRs associated with the use of medicines is mainly gathered via spontaneous reporting. Direct sourcing of information on personal experiences with a certain product from patients, among other means through social media analysis, opens a promising direction towards the improvement of existing approaches to collecting safety data

Superconductivity in ultra-thin carbon nanotubes and carbyne-nanotube composites: An ab-initio approach

The superconductivity of the 4-Å single-walled carbon nanotubes (SWCNTs) was discovered more than a decade ago, and marked the breakthrough of finding superconductivity in pure elemental undoped carbon compounds. The van Hove singularities in the electronic density of states at the Fermi level in combination with a large Debye temperature of the SWCNTs are expected to cause an impressively large superconducting gap. We have developed an innovative computational algorithm specially tailored for the investigation of superconductivity in ultrathin SWCNTs. We predict the superconducting transition temperature of various thin carbon nanotubes resulting from electron-phonon coupling by an ab-initio method, taking into account the effect of radial pressure, symmetry, chirality (N,M) and bond lengths. By optimizing the geometry of the carbon nanotubes, a maximum Tc of 60 K is found. We also use our method to calculate the Tc of a linear carbon chain embedded in the center of (5,0) SWCNTs. The strong curvature in the (5,0) carbon nanotubes in the presence of the inner carbon chain provides an alternative path to increase the Tc of this carbon composite by a factor of 2.2 with respect to the empty (5,0) SWCNTs. © 2017 Elsevier Lt

Определение удельного угла вращения плоскости поляризации в гиротропных кристаллах средней категории спектрофотометрическим методом

A large number of modern functional single crystals of the middle category belong to gyrotropic media. In these crystals, when light propagates along the optical axis, rotation of the plane of its polarization is observed. In this work a spectrophotometric method was used to obtain the dispersion dependences of the rotation angle of the polarization plane. This method is based on measuring the intensity of light passing through the polarizer–crystal–analyzer system, the crystal is a polished plane-parallel plate of a uniaxial gyrotropic crystal cut perpendicular to the optical axis. Measurements were carried out on a UV-Vis-NIR spectrophotometer Cary-5000 in the wavelength range of 200—1200 nm using polarizers — Glan–Taylor prisms. Polished plane-parallel plates of known SiO2 and α-LiIO3 crystals were used as samples. The obtained dispersion dependences of the spectral transmission coefficients are oscillating. Discrete values of the specific angles of rotation of the plane of polarization of light are calculated from the extremes on these dependencies. These discrete values can be approximated by the formulas Drude, Chandrasekhar and Vyshina, depending on what determines the nature of the rotational ability of the plane of polarization of light in each particular material. For the studied crystals, dependences of the modified Drude formula of the form 1/ρ = f(λ2) are plotted, these dependences should have a linear character in the case of an ideal crystal. The obtained experimental results correlate well with the available literature data. The advantages of this method are efficiency, the possibility of obtaining dispersion dependences of the specific rotation angle of the polarization plane, the need for a single sample, the possibility of assessing the nature of the rotational ability of specific crystals, the possibility of evaluating the structural perfection of the studied crystals.Большое количество современных функциональных монокристаллов средней категории относится к гиротропным средам. В таких кристаллах при распространении света вдоль оптической оси наблюдается вращение его плоскости поляризации. Для получения дисперсионных зависимостей угла вращения плоскости поляризации света использован спектрофотометрический метод. В основе этого метода лежит измерение интенсивности света, проходящего через систему поляризатор—кристалл—анализатор. Кристалл представляет собой полированную плоскопараллельную пластину одноосного гиротропного кристалла, вырезанную перпендикулярно к оптической оси. Измерения проведены на UV-Vis-NIR спектрофотометре Cary-5000 в диапазоне длин волн 200—1200 нм с использованием поляризаторов — призм Глана—Тейлора. В качестве образцов использованы полированные плоскопараллельные пластины известных кристаллов SiO 2 и α-LiIO 3. Полученные дисперсионные зависимости спектральных коэффициентов пропускания имели периодический характер. По экстремумам на этих зависимостях рассчитаны дискретные величины удельных углов вращения плоскости поляризации света. Эти дискретные величины могут быть аппроксимированы формулами Друде, Чандрасекхара и Вышина в зависимости от того, чем определяется природа вращательной способности плоскости поляризации света в каждом конкретном материале. Для исследованных кристаллов построены зависимости модифицированной формулы Друде вида 1/ρ = f(λ2), которые должны иметь линейный характер в случае идеального кристалла. Полученные экспериментальные результаты хорошо соотносятся с имеющимися литературными данными. Преимуществами данного метода является оперативность, возможность получения дисперсионных зависимостей удельного угла вращения плоскости поляризации, оценка природы вращательной способности конкретных кристаллов и структурного совершенства исследуемых кристаллов

Многоугловые спектрофотометрические методы отражения для определения коэффициентов преломления

Features of development and application of methods for performing refractive index measurements based on multi-angle spectrophotometric reflection methods are considered. The influence of the shape, size, and surface treatment of samples on their spectral reflection dependences is described. It is shown that it is possible to determine the refractive coefficients using two spectrophotometric methods: the reflection spectrum from one face at a small angle of incidence of light close to normal, and the reflection method at the incidence of light at the Brewster angle. The method of reflection at an angle of incidence close to normal can be used in the case of a non–absorbing sample characterized by an extinction coefficient not exceeding (10-6—10-4). This method is an «express method», because it allows you to immediately obtain the dispersion dependence of the refractive index. The method allows us to measure the dispersion dependences of refractive coefficients for samples whose shape excludes multiple reflections — plates with one polished side; plates of large thickness, polished on two sides; prisms or plates with non-parallel faces. When measuring using the Brewster method, there are no requirements for the value of the extinction coefficient of the sample (absorption), you can use a sample of any shape, including polished plates on both sides. However, the resulting values of refractive indices are discrete, and a large array of measurement results must be accumulated. The measurement accuracy of both methods was determined, which is Δ = ±0,001 with a confidence probability P = 0,95. The applicability of spectrophotometric measurement methods is shown for samples of gadolinium-aluminum-gallium garnet, which is related to cubic crystals, characterized by the presence of a single refractive index. It is shown that the values of the refractive indices obtained by these two methods are well correlated within the accuracy of measurements.Рассмотрены особенности разработки и применения методик выполнения измерений коэффициентов преломления, основанных на многоугловых спектрофотометрических методах отражения. Описано влияние формы, размеров и обработки поверхности образцов на их спектральные зависимости отражения. Показана возможность определения коэффициентов преломления двумя спектрофотометрическими методами: по спектру отражения от одной грани при малом угле падения света, близком к нормальному, и методом отражения при падении света при угле Брюстера. Метод отражения при угле падения, близком к нормальному, может применяться в случае непоглощающего образца, который характеризуется коэффициентом экстинкции не превышающем (10-6—10-4). Этот метод является «экспресс-методом», поскольку позволяет сразу получать дисперсионную зависимость коэффициента преломления. Метод позволяет измерять дисперсионные зависимости коэффициентов преломления для образцов, форма которых исключает многократные отражения: пластин с одной шлифованной стороной; пластин большой толщины, полированных с двух сторон; призм или пластин с неплоскопараллельными гранями. При измерении по методу Брюстера не предъявляются требования к значению коэффициента экстинкции образца (поглощению), можно использовать образцы любой формы, в том числе, полированные с двух сторон пластины малой толщины. Однако получаемые значения коэффициентов преломления дискретны, требуется накопление большого массива результатов измерений. Определена точность измерений обоих методов, которая составляет Δ = ±0,001 при доверительной вероятности P = 0,95. Применимость спектрофотометрических методик измерения показана для образцов гадолиний-алюминий-галлиевого граната, относящегося к кристаллам кубической сингонии и характеризующегося наличием одного коэффициента преломления. Показано, что значения коэффициентов преломления, полученные данными методами, хорошо соотносятся в пределах точности измерений

Исследование и оптимизация процесса инкапсулирования лекарственного вещества в полимерную оболочку в аппарате псевдоожиженного слоя

The drug encapsulation by enteric film fluid-bed coating has been investigated. Influence of each operation parameter on product quality has been estimated and optimal conditions included film thickness have been determined. The model drug release kinetics of encapsulation product has been studied.Исследован процесс инкапсулирования модельного лекарственного вещества в кишечнорастворимую полимерную оболочку в аппарате с псевдоожиженным слоем. Выявлен вклад каждого из параметров процесса в качество получаемого продукта, определены оптимальные условия для нанесения пленки, исследована кинетика высвобождения инкапсулированного препарата

A SORPTION OF URANIUM BY STRONG BASE ANION ION-EXCHANGE BEADS FROM SULFURIC-ACID LEACHING SOLUTIONS

Sorption of uranuim from sulfuric-acid leaching solutions by two gel type anion ion-exchange beads were explored. The Purolite A660 had a value of uranium capacity larger than AMP. Dynamic and static sorption parameters were identified for both elements