Chitosan-based Nanosystems as Drug Carriers

The formation and application of polymeric nanomaterials is great demandin science, industry, biotechnology, and medicine due to the possibility ofachieving a significant improvement in the physicochemical, mechanical,and barrier properties of polymers and using them as drug carriers andfillers, which is especially promising for biodegradable polymers such aschitosan and their derivatives. The article presents methods for creatingpolymer nanostructures based on polysaccharides and, in particular,chitosan. Obtaining nanostructured samples of chitosan using theapproaches of chemical transformation and modification of polysaccharidesis an urgent scientific problem, the solution of which makes it possible toobtain new polymer systems of great practical interest. The medical aspectsof the use of polymer carriers based on chitosan for the treatment of variousdiseases are discussed. The unique specificity of the properties of chitosanand nanomaterials derived from it, with the properties inherent in thisnatural polymer, can serve as a promising future, especially in the field ofmedicine

Determination of Hydrodynamic Parameters of Chitosan Stabilized Bimetallic Nanoparticles

The hydrodynamic characteristics of bimetallic Ag/Cu and Co/Ag nanoparticles stabilized by chitosan were determined. The polydispersity indexand the diameter of nanoparticles were observed to decrease in contrast tothe original polymer during the creation of chitosan stabilized bimetallicnanoparticles, decreasing from 0.342 to 0.12±0.04 and 2.5 micron to 180nm, respectively. However, the diffusion coefficient of chitosan was increased from 0.2 cm2 /s to 2.71 cm2 /s during the production of stable bimetallic nanoparticles. The lack of absorption bands at 500 nm and 700 nm-900 nm in the UV spectra of the samples suggests that in the presence ofa reducing agent, copper (II) and cobalt (II) ions undergo full reduction.The relationship between the synthesis conditions and the kind of structureof bimetallic nanoparticles “core-shell” has been discovered. Silver atomshave been shown to be both a core and a shell, depending on the synthesisconditions and chemical nature of metal ions

Lexical-Semantic features of the arabic cognates related to the educational process

The word-stock of the Uzbek language consists of native and assimilated words. Until the early 20th century, the assimilated stratum was enriched with Persian-Tajik and Arabic words. By the beginning of the 20th century, Russian words, and later international words, began to intensify. Although the process of mastering Persian-Tajik and Arabic words slowed down, the mastery of these languages retained the main position of the explanatory dictionary of the Uzbek language. Farsi-Tajik and Arabic words began to acquire the status of their stratum in relation to Russian-international words. Most of these words are difficult to distinguish without etymological analyses and dictionaries. Such similarities were accepted as similarities only by scholars, and in colloquial terms they became the words of their class. The processes of semantic development of borrowed words occurred within the Uzbek language. In this article the changes of roots associated with the learning process, observed during the historical development of semantics of Arabic lexemes are maximally highlighted

Role of Fractals in Perovskite Solar Cells

The interface engineering plays important role in fabrication of the tandem and perovskite based solar cells. Recent experiments show that the interface effects caused by the coupling of the electron bands and the pairing of geometry of contacting surfaces. In particular, it has been experimentally revealed that the transition from planar to the rough interface improves many photoelectric parameters of the device. It means that the value of the fractal dimension of the interface may be key factor in device performance. It is possible to formulate two problems: firstly, the understanding on simple models why the electrical properties at fractal interfaces are improved, and, secondly, to discuss one of the most promising approaches in modern electronics, namely technology of radiation applications in the creation of rough interfaces. Thirdly, the problem of photodegradation is analyzed in detail in the structures containing the fractal interfaces. On the basis of the constructed models, it was found: i) increase of roughness (fractal) of interface structure can enhance the role of total internal light reflection effect, thereby increasing the effective light path, and therefore, the number of generated e-h-pairs; ii) the curvature of the surface leads to the shift of Tamm levels both to the borders of allowed bands, and to the middle of the band gap; it opens the way of the control of carrier recombination on the interface; iii) surface Tamm orbitals interact differently each with other on the convex and concave areas; it leads to the different probability of defect formation and, consequently, reduces the fractal interface, inhibiting the effect of increasing of the photocurrent associated with the fractal interface (new channel of photodegradation)

Polyethylene/Layered Aluminosilicate Nanocomposites: Investigation of Thermal Stability under Static and Dynamic Conditions

Based on linear low-density polyethylene and maleated polyethylene a polymer nanocomposites containing modified montmorillonite have been obtained, structure is investigated by XRD analysis. In turn, by the methods of thermal analysis in static and dynamic modes, the resistance of polymer nanocomposites to oxidative destruction it was investigated. In parallel with this, a comparative analysis of the thermal stability of polymer nanocomposites and polymer compositions containing commercially available organic antioxidants for stabilization of materials based on polyolefins. By results of the analysis carried out in a dynamic mode, for a series of polymer composites the activation energy of thermooxidative destruction was calculated. It is shown that the nanocomposites based on polyethylene, containing the modified montmorillonite not only not concede to polymer compositions with antioxidants in to thermal stability, but also exceed their. Accelerated tests, carried out at relatively high temperatures allowed evaluate the durability of polymer nanocomposites to thermooxidative destruction. Received results allow approve about a long-term thermal stability of these materials in the processing, and in the exploitation conditions

Features of the Functional State of the Hypophysis-Ovarian System and Processes of Lipid Peroxidation – Antioxidant Protection in Women with Hyperandrogenism of Ovary Genesis in the Early Reproductive Period

Background. Women with polycystic ovary syndrome in the early reproductive period have hormonal and metabolic dysfunction and an increased risk of long-term health consequences. The article presents the results of the study of hormonal indicators and the parameters of lipid peroxidation – antioxidant protection in women  with polycystic ovary syndrome in early period of reproductive age (from 18 to 35 years old).Aim: evaluation of the functional state of the pituitary-ovarian-adrenal system and the lipid peroxidation – antioxidant protection system and the establishment of intersystemic relationships in women of the early reproductive period with polycystic ovary syndrome.Materials and methods. Study included 33 women with ovarian hyperandrogenism and 17 healthy women of early reproductive age. A questionnaire survey, general medical and gynecological examinations, and ultrasound examination of the pelvic organs were conducted. Immunoenzyme method for detection the concentration of hormones, spectrophotometric and spectrofluorometric (determination of the concentration of  lipoperoxidation products, parameters of antioxidant protection), statistical methods were used.Results. Women of early reproductive age (from 18 to 35 years old) with polycystic ovary syndrome characterized by an increase of 17-OH-progesterone by 2.2 times (p = 0.0005), and dehydroepiandrosterone sulfate by 1.3 times (p = 0.0001). A decrease in the total antioxidant activity of the blood by 25 % (p = 0.0005), an increase in the content of oxidized glutathione by 14 % (p = 0.0001) and a decrease in the concentration of retinol by 26 % (p = 0.0012) compared to the control values were shown. The increase in the  degree of oxidative stress was indicated by the value of the coefficient of oxidative stress equal to 2.8.Conclusion. The obtained data indicate the features of the functional state of the pituitary-ovarian-adrenal system and the processes of LPO–AOP, as well as the need for timely diagnosis and effective correction of hormonal and metabolic disorders in women with polycystic ovary syndrome in the early reproductive period

Modified Ross operation (literature review)

One of the surgical methods for treating aortic valve pathology is the Ross operation, which was proposed by the British cardiac surgeon D. Ross in 1967. Numerous studies have shown excellent long-term outcomes of this operation. However, in some patients, pulmonary autograft dilatation may occur in the long term. To avoid this complication, technical modifications of this procedure have been proposed. A literature review on modified Ross operation as a prevention of pulmonary autograft dilatation is presented

Pulmonary homograft dysfunction after Ross procedure in adults: a single center experience

The Ross procedure was first proposed by Donald Ross in 1967. Numerous studies show excellent long-term outcomes of the Ross operation. One of its disadvantages is the intervention on two valves due to pulmonary homograft dysfunction.Aim.  To study long-term outcomes of pulmonary homograft use after Ross operation (cumulative incidence of pulmonary homograft dysfunction, freedom from reoperation on pulmonary homograft, long-term survival, predictors of pulmonary homograft dysfunction) using data from one Russian center.Material  and  methods. A retrospective study included patients aged 18 years and older with aortic valve disease who underwent Ross procedure from April 2009 to December 2020 by a single surgeon. The age of the patients was 35 (26-44) years (men, 159 (75%)). Infective endocarditis as a cause of aortic valve pathology was diagnosed in 55 (26%) patients. Bicuspid aortic valve was diagnosed in 131 (62%) patients. The median follow-up period was 79 (26,5102,7) months.Results. Combined interventions were performed in 40 cases (18,9%). The modified Ross procedure was used in 54 (25,5%) cases (intra-aortic — 29, using Dacron tube graft — 25). Inhospital mortality was 0,5%. The 5- and 10-year allcause survival rates were 98,5% and 95,4%, while the 10-year cumulative pulmonary valve reoperation rate and pulmonary homograft dysfunction was 4,6% and 35,2%, respectively. The only factor affecting pulmonary homograft dysfunction was patient age ≤30 years (odds ratio =0,2 with 95% confidence interval: 0,06-0,7; p=0,02).Conclusion. Fresh pulmonary homografts have a low incidence of dysfunction and reintervention after Ross procedure. Young age is the only independent risk factor for pulmonary homograft dysfunction

Дилатация легочного аутографта и ее факторы риска после классической процедуры Росса: ретроспективное одноцентровое исследование

   Introduction. Aortic valve replacement with pulmonary autograft (Ross procedure) demonstrated excellent immediate and long-term results. Dilation of the pulmonary autograft in the long-term period is the main reason for repeated surgery. Aim: to study the prevalence of pulmonary autograft dilatation and its risk factors.   Materials and methods. From April 2009 to December 2022, 158 patients underwent classical Ross surgery. Inclusion criteria: patients aged 18 and older, patients who underwent classical surgery. Exclusion criteria: patients under 18, modifi ed methods of Ross procedure. Follow-up period: 104 (49–124) months.   Results and discussion. The median age of patients was 33 (25–43) years. Hospital mortality accounted for 0.6 %. Perioperative myocardial injury was 3.8 %, conduction disorder requiring permanent pacemaker implantation accounted for 1.9 %, the incidence of strokes and acute kidney injury requiring hemodialysis was 0.6 %. Ten-year freedom from autograft reoperation was 88.4. Ten-year freedom from reoperation for aortic aneurysm accounted for 92 %. Predictors of autograft dilatation in the long-term period were: age (OR: 0.942; 95% CI: 0.901–0.984, p = 0.008) and the initial size of sinuses of Valsalva (OR: 1.18; 95% CI: 1.027–1.215, p = 0.01).   Conclusion. Ten-year freedom from autograft reoperation due to aortic dilatation and freedom from aortic dilatation ≥ 45 mm was 92 % and 37.2 %, respectively. The main predictors of autograft dilatation in the postoperative period are the age and the initial diameter of the sinuses of Valsalva.   Введение. Протезирование аортального клапана (АК) легочным аутографтом (операция Росса) продемонстрировала отличные непосредственные и отдаленные результаты. Дилатация легочного аутографта в отдаленном периоде является основной причиной повторной операции.   Цель: изучить распространенность дилатации легочного аутографта и изучить факторы ее риска.   Материалы и методы. В период с апреля 2009 по декабрь 2022 гг. 158 больным выполнена операция Росса классическим способом. Критерии включения в исследования: возраст больных 18 лет и старше; больные, кому была выполнена операция классическим способом. Критерии исключения: пациенты моложе 18 лет, модифицированные методики операции Росса. Период наблюдения 104 (49–124) месяца.   Результаты и обсуждение. Медиана возраста больных составила 33 (25–43) года. Госпитальная летальность — 0,6 %. Периоперационное повреждение миокарда — 3,8 %. Нарушение проводимости, потребовавшее имплантации постоянного ЭКС, — 1,9 %, частота инсультов и острого почечного повреждения, потребовавшего гемодиализа, — 0,6 %. Десятилетняя свобода от реоперации на аутографте — 88,4. Десятилетняя свобода от реоперации по поводу аневризмы аорты — 92 %. Предикторами развития дилатации аутографта в отдаленном периоде стали: возраст (ОШ 0,942; 95 % ДИ 0,901–0,984, р = 0,008) и изначальный размер синусов Вальсальвы (ОШ 1,18; 95 % ДИ 1,027–1,215, р = 0,01).   Заключение. Десятилетняя свобода от реоперации на аутографте в связи с дилатацией аорты и свобода от дилатации аорты ≥ 45 мм составили 92 и 37,2 % соответственно. Главными предикторами развития дилатации аутографта в послеоперационном периоде являются изначальный диаметр синусов Вальсальвы и возраст