Исследование термической деструкции чистых и растворенных в воде алифатических спиртов

By the method of isothermal pressure increasing in a closed system starting temperatures (TS) of thermal decomposition of aliphatic alcohols (methanol, ethanol, 1-propanol and 1-butanol) in their water solutions depending on composition are obtained. Values of TS depending on composition (x) and number of carbon atom (C) are described by the polynomial equation: 544.258 2 28.826 10 3 2 65.617 6.378 10 2 ( , ) 23.622 + − + ⋅ − T x N = x − x + ⋅ N N . It is shown that the rate of alcohol decomposition depends on temperature and concentration (in water-alcohol solution). To estimate rate of thermal decomposition of alcohols we used change of pressure of system in a unit of time at constant temperature and volume (closed system). Reaction rate constant was calculated by formula: dτ dp p k = 1 ⋅ , where k – reaction rate constant; p – pressure; τ – time; dp/dτ – rate of reaction. Values of kinetic and activation parameters of alcohol decomposition in the range of temperatures 583.15–663.15 К are estimated.Методом определения изотермического роста давления в закрытой системе получены температуры начала термической деструкции (разложения) алифатических спиртов (метанол, этанол, 1-пропанол и 1-бутанол) и их водных растворов в зависимости от состава. Показано, что скорость деструкции молекул спиртов зависит от температуры, а растворенных в воде – и от их концентрации. Оценены значения кинетических и активационных параметров деструкции чистых и растворенных в воде спиртов в интервале температур 583.15–663.15 К

ПАРЦИАЛЬНЫЕ МОЛЯРНЫЕ ОБЪЕМЫ СМЕСЕЙ ВОДА – АЛИФАТИЧЕСКИЙ СПИРТ

In this work we used results of p,Vm,T,x-measurements of water – alcohol mixtures (methanol, ethanol and 1-propanol) with x = 0.2, 0.5, 0.8 in the range of temperatures 613.15–653.15 К and pressures 20–50 MPa for calculation of partial molar volumes. The dependence of molar volume on concentration Vm = f(p,x)T is described by a polynomial equation with relative deviation 0.5%. A characteristic feature for all of three studied mixtures is that an insignificant growth of the partial molar volumes of water and a decrease of the partial molar volumes of the alcohols take place with increasing alcohol concentration. Water – hydrocarbon mixtures in the critical state have a similar character of the dependence of partial molar volume on concentration.В работе для расчета парциальных молярных объемов использованы собственные экспери-ментальные p,Vm,T,x-зависимости (x – концентрация спирта в мольных долях) систем вода – алифатический спирт (метанол, этанол, н-пропанол) состава x: 0, 0.2, 0.5, 0.8, 1 в сверх-критической области, описанные полиномиальным уравнением состояния вида со средней относительной погрешностью 0.5%

A new approach to use of oral mucosa in reconstructive urethral surgery: micrografts

Introduction. Treatment of patients with complex urethral strictures is an actual problem of reconstructive urology. After multi-staged urethral surgery with multiple revisions the new reconstruction is limited by paucity of plastic material (for grafts and flaps). In-thing, new materials for urethral reconstruction (various auto, allo and xenografts) are still being developed in reconstructive urethral surgery.Purpose of the study. To study the possibility of using oral mucosa micrografts to form the urethral plate in the multi-stage surgery for patients with extended urethral strictures.Materials and methods. In the experimental study, male Wistar rats (22 individuals) weighing 300 – 400 g underwent a full-thickness skin wound after intramuscular sedation. We used the wound chamber (12 mm diameter) to exclude the wound contraction. The oral mucosa graft was harvested (6 mm in diameter). After pre-fabrication, the graft was minced to fragments < 1 mm2. Micrografts with fibrin-thrombin glue were applied to the wound. By day 45, the epithelial plate was excised for histological examination. In the clinical study, 4 patients with recurrent penile urethral strictures were treated with staged urethroplasty with urethral plate formation using oral mucosa micrografts. The average length of the stricture was 7.5 ± 1.2 cm (with extremely narrow and obliteration sites). The urethral plate was formed as the first stage. The preparation of the graft bed and oral mucosa grafts harvesting was carried out according to the standard procedure. Micrografts preparation and implantation was carried out as in experimental part of this study. After 6 months, neourethra tubularization was performed. The patients were evaluated every 3 months after the final stage of urethroplasty (uroflowmetry, ultrasound, X-ray, PROM-USS). The median follow-up was 9 months (3 – 18 months).Results. On day 15, in the experimental study, in 16 of 22 (72.7%) rats, the wound chambers had focal growth of the oral mucosa epithelium. On day 45, the wounds healed completely healed with oral mucosa. The final area of the plate was 78 ± 12 mm2. In the clinical study, 6 months after the first stage, all patients (n = 4) had a urethral plate covered with an oral mucosa epithelium without scar formation and sufficient for neurethra tubularization. All patients underwent urethral tubularization. After catheter removal, all men urinated. After 9 months (median follow-up, n = 3), the Qmax was 22.7 ± 4.2 ml/s, the post-void residual urine was 34.8 ± 2.2 ml, the total PROM-USS score was 7.4 ± 1.2, urethral lumen is preserved. All patients showed high satisfaction with the treatment.Conclusion. The oral mucosa micrografts showed good take in heterotopic transplantation (72.7%) with the formation of an epithelial layer on the wound surface. The final mucosal plate area 3 times exceeded the initial micrografts area. This initial clinical experience of using oral mucosa micrografts shows the new possibility of this technology in reconstructive urethral surgery, especially in patients with complex urethral strictures

Сравнение внутрирубцовых систем мониторинга физиологического состояния крупного рогатого скота

This paper explores a method for the early detection of subacute rumen acidosis through continuous monitoring of rumen content acidity using wireless pH sensors. The study emphasizes the importance of reliable device operation and measurement accuracy as primary requirements for such devices. (Research purpose) This study aims to evaluate the functionality and accuracy of the eBolus (USA) and BoviSan (Russia, FSBSI FSAC VIM) sensors throughout their declared service life of 150 days. (Materials and methods) Three dairy cows with a rumen fistula were administered two boluses from each manufacturer during a period of 154 days. In order to ensure accurate measurements, the boluses were activated and calibrated prior to use. On the first day of data collection, the activated and calibrated boluses were sequentially immersed in buffer solutions with a pH of 4 and pH of 7. The buffer solutions were maintained at a controlled temperature of 39 degrees Celsius for a minimum of 2 hours. At 14-day intervals, the boluses were extracted from the rumen and subjected to retesting in buffer solutions. (Results and discussion) For BoviSan, the confidence interval for the mean difference suggests a systematic negative pH bias (– 0.33 to – 0.25). The average lifespan of the eBolus was determined to be 82 days, with a range of 28 to 126 days. In contrast, BoviSan boluses consistently recorded pH levels throughout their announced lifespan. Statistical analysis of the data revealed a 95% confidence interval for the mean pH difference of the eBolus boluses (– 0.02 to 0.19), indicating no significant bias. Conversely, the confidence interval for the mean difference in pH for BoviSan suggested a consistent negative bias (– 0.33 to – 0.25). (Conclusions) In practical applications, it is essential to ensure enhanced reliability of eBolus boluses, while prioritizing higher measurement accuracy with BoviSan boluses.Отметили, что для раннего выявления подострого ацидоза рубца может использоваться метод, основанный на постоянном контроле за уровнем кислотности рубцового содержимого с помощью беспроводных датчиков pH. Основными требованиями к таким устройствам являются надежная работа и точность измерения. (Цель исследования) Определить функциональность и точность датчиков eBolus (США) и BoviSan (Россия, ФГБНУ ФНАЦ ВИМ) в течение заявленного срока службы 150 дней. (Материалы и методы) Трем дойным коровам с фистулой рубца на 154 дня вводили по два болюса от каждого производителя. В первый день измерений болюсы после активации и калибровки выдерживали последовательно в буферных растворах с pH 4 и pH 7 при регулируемой температуре (39 градусов Цельсия) не менее 2 часов. Через каждые 14 дней болюсы извлекались из рубца и повторно тестировались в буферных растворах. (Результаты и обсуждение) Средний срок службы eBolus составил 82 дня (от 28 до 126 дней). В сравнении с ними болюсы BoviSan регистрировали pH в течение всего заявленного срока службы. Доверительный интервал 95% средней разницы рН для болюсов eBolus (от –0,02 до 0,19) не показал систематической ошибки. У BoviSan доверительный интервал средней разницы предполагает систематическое отрицательное смещение pH (от –0,33 до –0,25). (Выводы) Для реального использования болюсы eBolus должны работать более надежно, а болюсы BoviSan должны обеспечивать более высокую точность измерения. 

Локальные гемостатические средства в хирургической практике

At present, in emergency surgery, great importance is attached to reliable intraoperative hemostasis, for the achievement of which local hemostatic agents are used. The use of these funds tends to increase. The hemostatic agents are divided on 3 main groups. In turn, each group has its own physical and chemical characteristics and different ways of application. The surgeon have task of choosing and correctly using a specific hemostatic agent in a specific clinical situation, especially an emergency one. В настоящее время в экстренной хирургии большое значение придается надежному интраоперационному гемостазу, для достижения которого имеет место применение локальных гемостатических средств. Использование данных средств имеет тенденцию к увеличению. Сами гемостатические агенты подразделяются на три основные группы. В свою очередь каждая группа имеет свои физико-химические особенности и различные способы применения. Перед хирургом стоит задача выбрать и правильно использовать конкретное гемостатическое средство в конкретной клинической ситуации, особенно экстренной.

Research of thermal destruction of aliphatic alcohols in pure state and dissolved in water

By the method of isothermal pressure increasing in a closed system starting temperatures (TS) of thermal decomposition of aliphatic alcohols (methanol, ethanol, 1-propanol and 1-butanol) in their water solutions depending on composition are obtained. Values of TS depending on composition (x) and number of carbon atom (C) are described by the polynomial equation: 544.258 2 28.826 10 3 2 65.617 6.378 10 2 ( , ) 23.622 + − + ⋅ − T x N = x − x + ⋅ N N . It is shown that the rate of alcohol decomposition depends on temperature and concentration (in water-alcohol solution). To estimate rate of thermal decomposition of alcohols we used change of pressure of system in a unit of time at constant temperature and volume (closed system). Reaction rate constant was calculated by formula: dτ dp p k = 1 ⋅ , where k – reaction rate constant; p – pressure; τ – time; dp/dτ – rate of reaction. Values of kinetic and activation parameters of alcohol decomposition in the range of temperatures 583.15–663.15 К are estimated

Partial molar volumes of components of water – aliphatic alcohol mixtures

In this work we used results of p,Vm,T,x-measurements of water – alcohol mixtures (methanol, ethanol and 1-propanol) with x = 0.2, 0.5, 0.8 in the range of temperatures 613.15–653.15 К and pressures 20–50 MPa for calculation of partial molar volumes. The dependence of molar volume on concentration Vm = f(p,x)T is described by a polynomial equation with relative deviation 0.5%. A characteristic feature for all of three studied mixtures is that an insignificant growth of the partial molar volumes of water and a decrease of the partial molar volumes of the alcohols take place with increasing alcohol concentration. Water – hydrocarbon mixtures in the critical state have a similar character of the dependence of partial molar volume on concentration

THERMOELECTRIC DEVICES FOR CONTRAST THERMAL EFFECT ON THE INDIVIDUAL ZONES OF THE HUMAN BODY

The article considers various design options for devices contrast to the thermal effect on the individual zones of the human body

STUDY OF A FLOWING-TYPE HEAT TRANSFER INTENSIFIER USED AS PART OF A THERMOELECTRIC SEA WATER DESALINATION SYSTEM

Objectives To analyse the thermophysical processes in the thermoelectric heat transfer intensifier operating as part of a desalination system based on semiconductor thermoelectric converters.Method A mathematical model for the design of a desalter containing a thermoelectric heat exchanger, which provides for the use of heat flows by natural thermal conductivity due to so-called heat channels, is proposed. The proposed method of using additional heat sinks on the heat-absorbing side of the device and additional heat sources on the fuel side determines the need for a new mathematical model that differs from the known mathematical models describing heat transfer in the heat transfer flowing-type intensifier.Results The analysis of modelling results shows that a significant contribution to the temperature field of heat conductors is made when considering the heat transfer over the heat channels. The value of the contribution is the greater, the higher the thermal conductivity of the heat channels and the temperature difference between the heat conductors and the surface of the heat channels. In accordance with their purpose, flow-type thermoelectric heat transfer intensifiers (THTIs) for desalination applications must ensure efficient heat transfer from the cooled fluid flow to the heated fluid flow. The results show that, at a given limited length of the heat exchanger, the use of a thermoelectric battery together with heat channels allows equality of temperatures of heat conductors at the output to be achieved.Conclusion The modelling results show that, under the operating conditions of the thermal battery in intensifier mode, the length of the heat exchanger shall not exceed the value, at which the temperature of the heat conductor at the outlet becomes equal. The system solution provides the required length of the thermal battery, which allows equality of coolant temperatures to be achieved at the exit from the THTI operation mode. Following the logic of the desalter scheme under consideration, it is obvious that the reduction in the length of the heat exchanger, with all other things being equal, gives a reduction in the mass and size of the device as a whole