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Abstract The results from studies of a high-voltage unit of shock-ionized dynistors in the switching mode of current pulses with an amplitude of several kiloamperes and a rise rate of up to 100 kA/μs are presented. The control circuit of this unit with a front sharpener of the trigger voltage pulses is described, which provides a significant reduction in energy losses in dynistors.

Abstract Monounit and modular switches of high-power current pulses with an operating voltage of 12 kV, made on the basis of series-connected shock ionized dynistors, are described. The switching processes of these switches are studied. The dependence of switching energy losses on the control pulse power is determined. The possibility of switching nanosecond current pulses with an amplitude of several kiloamperes at a frequency of several hundred hertz is shown.

Aim. To analyze various strategies aimed at mitigating complications of the portal hypertension syndrome at the Minsk Scientific and Practical Center for Surgery, Transplantology, and Hematology.Material and methods. Patients who had undergone different types of treatment were retrospectively observed: shunt surgery to form portacaval anastomoses, transjugular portosystemic shunt placement, and liver transplantation. The following parameters were analyzed: incidence of complications, hospital mortality rate, survival rate, and perioperative indicators.Results. Since 1980, 131 shunt surgeries have been performed at the Center, while 880 liver transplantations and 232 transjugular portosystemic shunt placement procedures have been performed since 2008. Among 68 patients with compensated cirrhosis who had undergone shunt placement, no hospital mortality rate was reported, whereas in patients with Child-Pugh B cirrhosis and Child–Pugh C cirrhosis, it reached 19.5% and 87.5%, respectively. Following TIPS, the overall case mortality rate amounted to 9.9% (following TIPS prior to transplantation – 8.2%, following TIPS used as the final treatment – 12.8%). After liver transplantation, in-hospital mortality rate reached 7.7%.Conclusion. Over 50 years, the strategy for managing portal hypertension has undergone significant changes due to the establishment of institutions providing a complete cycle of all treatment measures for such patients. Patients suffering from the complications of the portal hypertension syndrome tend to receive the most effective treatment in hospitals having experience in rational conservative therapy, endovascular procedures, and transplantation.

Abstract A high-voltage pulse generator is considered that contains an output circuit based on series-connected assemblies of reverse switched-on dynistors and drift step-recovery diodes. It forms voltage pulses with a rise time of 4 ns and an amplitude of 24 kV across a load of 50 Ω. The results of using the generator for creating discharges in atmospheric air are presented. The generator forms discharge-current pulses with an amplitude of 1.7 kА and a rise time of 900 ns at a frequency of 100 Hz and switches an energy of ~3 J to the charge channel. The possibility of a significant increase in the switched energy has been shown.

A generator of high-power nanosecond pulses is described that contains a high-voltage unit, which is based on a magnetic-compression circuit and a diode current interrupter, and a high-voltage transistor unit, which provides high-efficiency energy switching to the high-voltage unit. The results of using this generator in an experimental plasma installation that was developed for studying the possibility of synthesizing silicon from a mixture of H2 and SiF4 are presented.

A generator of rectangular voltage pulses with an amplitude of ~30 kV, a rise time of ~1.5 µs, and a duration of up to 10 µs is described that contains a step-up pulse transformer, as well as thyristor switches with low and high operating voltages, which form, respectively, the front and fall of output pulses. The possibility of generating volume discharges with a frequency of 1 kHz in a barrier-type reactor designed for biological research is shown.

A high-power generator based on small TB133-250-24 thyristors, which contains four thyristor modules with an operating voltage of 24 kV, is considered. The parameters of control pulses and protective circuits that provide low switching energy losses in series-connected thyristors and the absence of dangerous overvoltages upon their enabling are determined. The results of generator testing at a frequency of 10 Hz are presented. It is able to switch microsecond current pulses with an amplitude of 12 kA and a front of 0.8 μs. The possibility of scaling these results is shown.

A transistor generator of microsecond voltage pulses with an amplitude of up to 40 kV, which contains an unstabilized power source, a low-voltage capacitive energy storage device, and a step-up pulse transformer, is considered. It allows one to efficiently recover the energy reflected from a load upon a sharp change in its electrical resistance and provides a highly stable (with a spread below 5%) value of the charging voltage of the capacitive storage device (1 kV), which does not change upon changes in the operating conditions from short circuit to idle operation. The results of testing the generator at an output-voltage pulse repetition frequency of up to 1 kHz are presented and the possibility of its significant increase is shown.

Введение. Одна из главнейших проблем современной трансплантологии – иммунологическая дисфункция трансплантата, частота развития которой достигает 40%. Пункционная биопсия в 2,2% случаев сопряжена с развитием осложнений и может привести к летальному исходу. Цель исследования – разработка методики неинвазивной диагностики отторжения трансплантата печени в отдаленном периоде после операции с использованием терминально-дифференцированных эффекторных CD8+Т-лимфоцитов. Материал и методы. Проведено пилотное одноцентровое обсервационное ретроспективное случай-контроль исследование, включающее 45 реципиентов после ортотопической трансплантации печени. По клиническому течению послеоперационного периода пациенты стратифицировались на 2 группы в зависимости от наличия эпизодов отторжения в трансплантате. Все пациенты после трансплантации получали иммуносупрессивную терапию. Иммунофенотипы реципиентов определялись методом проточной цитофлоуметрии. Всем пациентам была выполнена пункционная биопсия трансплантата. Результаты. Результаты исследования биоптатов трансплантатов печени показали, что 14 пациентов (31%) из 45 имели морфологические признаки отторжения. У пациентов с отторжением был достоверно более высокий уровень абсолютного количества СD8+ Тemra-клеток, что составило 0,23 (0,14; 0,38) ×109/л по сравнению с пациентами без отторжения – 0,09 (0,034; 0,16)×109/л (р=0,034). Результаты ROC- анализа показали, что наиболее оптимальный порог отсечения уровня СD8+ Тemra-лимфоцитов при диагностике иммунологической дисфункции трансплантата печени в отдаленном периоде составил 0,1882×109/л, чувствительность и специфичность при данном пороге отсечения составила 73,33 (95% ДИ: 44,9-92,0) и 96,55 (95% ДИ: 82,2-99,4,) соответственно. Выводы. Увеличение абсолютной численности терминально-дифференцированных эффекторных CD8+ Т-лимфоцитов является диагностическим критерием у пациентов с иммунологической дисфункцией трансплантата в позднем посттрансплантационном периоде. Высокая чувствительность и специфичность порога отсечения абсолютного количества CD8+ Тemra-лимфоцитов у пациентов после трансплантации печени и достоверная разница между количеством клеток у пациентов с нормальным послеоперационным течением, имеющих иммунологическую дисфункцию трансплантата, позволяет рассматривать субпопуляцию Т-лимфоцитов как прогностический биомаркер отторжения в позднем посттрансплантационном периоде. Корреляция этого показателя с результатами морфологического исследования делает его альтернативным и, главное, безопасным неинвазивным способом ранней диагностики отторжения.

The results of experimental studies of optimized shock-ionized dynistors (SIDs) when switching high-power current pulses with a nanosecond duration are presented. It is shown that the efficiency of the SID switching process can be increased by introducing uniformly distributed equal-sized diode sections, whose total area is significantly less than the total area of the semiconductor structure of the dynistor, into its four-layer structure. The results of comparative studies of optimized SIDs with different areas of structures and different maximum allowable voltages in the stationary state are presented. Explanations of the results are given.

The paper presents results of testing semi-coke as a carbon reducing agent in the production of manganese and silicon alloys. The fundamental possibility of using semi-coke in the carbon part of the charge as a basic reducing agent to produce ferrosilicon manganese is established. It is noted that a new reducing agent in its pure form works worse than in a mixture with coal. The greatest synergistic effect in the production of ferrosilicon manganese was achieved during the interaction of semi-coke with coal, while the following indicators were obtained: maximum furnace productivity of 43 t/day, maximum extraction coefficient of 87.9%, and minimum specific dust formation of 49 kg/t of alloy. In the production of ferrosilicon, the use of a new reducing agent did not give a significant positive effect, due to its low structural strength. It was revealed that the structure and type of the reducing agent affect the furnace performance: when using a reducing agent with a higher reactivity in the charge, it is possible to obtain higher furnace performance. In the production of ferrosilicon, a change in the specific dust generation is closely related to the level of daily production and specific energy consumption and can serve as an indicator of furnace operation. The furnace performance, ceteris paribus, is determined by the amount of useful power input. With an excess of carbon in the charge an increase in useful power leads to a slight increase in the furnace performance, but at the same time, the energy consumption and specific dust formation significantly increase. It is shown that the influence of technological factors on the technical and economic indicators of melting is determined by the degree of electrode seating in the furnace.

An Erratum to this paper has been published: https://doi.org/10.1134/S0020441223010311

An Erratum to this paper has been published: https://doi.org/10.1134/S002044122301030X

This paper presents the results of a study of reversely switched dynistors (RSDs) with an operating voltage of 2.3 kV and a structure diameter of 12 mm in an unconventional mode, when they commutate current pulses with very short durations (a few microseconds). In this mode, we studied the dependence of the switching energy loss on the amount of charge that passes through the RSDs during the flow of the control current, which is reversed with respect to the main current. It is shown that a sufficiently powerful control action will result in the RSDs under study having a very low energy loss and being able to effectively commutate microsecond current pulses with an amplitude of >10 kA. It is found that if a rise time of the commutated current pulses is less than 200 ns, the efficiency of the RSD switching significantly decreases. The results concerning the use of the RSDs under study in high-voltage generators are presented. The generators are able to commutate a pulsed power of tens of MW in less than 1 µs at a repetition rate of hundreds of Hz. Finally, this paper suggests ways to increase the power of generators.

A small generator of high-power high voltage nanosecond pulses with a 12 V power source is considered. At a load of 75 Ω, it provides the generation of pulses with an amplitude of ~17 kV, a front of ~4 ns, and an energy of ~15 mJ. The maximum pulse repetition rate is 15 kHz. The generator contains an inductive energy storage device and a capacitive storage device with an operating voltage of 1 kV. The formation of high voltage pulses is carried out by a high voltage current chopper in the form of a block of drift diodes with a sharp recovery. The conditions for the effective operation of the diodes are provided by a block of parallel-connected IGBT transistors with an operating voltage of 1.2 kV. The possibility of using a generator for multispark ignition of the spark plug of an internal combustion engine is shown.

A highly stable and highly efficient electroexplosive device for initiating powerful shock waves that contained a detonator based on a narrow copper foil coated with a polymer film and a semiconductor generator of submicrosecond current pulses that provides an electric explosion of the foil in a time of ~70 ns are considered. The possibility of using the developed device for detonating powerful explosives that are resistant to thermal and mechanical external influences is demonstrated.

The effect of pinacidil was studied on calcium-loaded rat heart mitochondria (RHM) in the presence of succinate and rotenone. In experiments with pinacidil, the swelling of these mitochondria increased in media with NH4NO3 or K‑acetate, but the inner membrane potential DΨmito and state 3 or 2,4-dinitrophenol-uncoupled respiration of these organelles were decreased due to opening of the mitochondrial permeability transition pore in the inner membrane. These effects were inhibited by cyclosporin A and ADP. It was concluded that the protective effect of pinacidil in the cardiac muscle ischemia/reperfusion may be associated with stimulation mitochondrial swelling and a decrease in RHM calcium overload resulted in a decrease in DΨmito due to the soft uncoupling pinacidil effect.

A high-voltage device for generating low-temperature plasma in water that is saturated with air bubbles is considered. It contains a discharge chamber and a generator of voltage pulses with an amplitude of ~30 kV and a rise time of ~5 μs, which is able to form spark discharges with an energy of ~1 J at a frequency of several hundred hertz. The electric circuit of the generator of discharges in water, which provides its high efficiency, and the design of the discharge chamber, which allows formation of parallel air flows through the water-filled interelectrode gap, are described. The results of studies of electric-discharge processes and the results of the chemical analysis of water samples that are enriched with products of plasmochemical reactions are presented. The possibility of the accelerated development of plants that are irrigated with plasma-treated water is shown.

The results of pilot studies of silicon shock-ionized dynistors (SIDs), which belong to the class of thyristor-type semiconductor devices that are able to be switched to a highly conducting state within a time shorter than 1 ns upon application of a short overvoltage pulse that initiates an impact-ionization process, are presented. The excellent characteristics of SIDs in the mode of switching high-power current pulses of nanosecond duration are demonstrated. Experiments are described that indirectly confirm the ability to initiate the process of subnanosecond switching of an SID by holes that are injected from a p+ emitter.

The results of investigations of shock-ionized dynistors (SIDs), which differ in the value of the maximum voltage that is blocked in the static state, the structure diameter, and the profile of the edge contour (chamfer), are presented. It is shown that when SIDs with different maximum permissible voltages switch high-power current pulses of nanosecond duration they have similar values of switching energy losses. Experiments that indirectly confirm a uniform current distribution over the working area of an SID after its switching-over are described. The results of comparative studies of SIDs with forward and inverse chamfers are presented, which indicate that they have different switching characteristics. An explanation of these results is given.

An experimental generator of microsecond pulses with an output current amplitude of ∼1 kA and an output voltage amplitude of ∼1 kV was developed. The generator is able to operate on a load whose electrical resistance changes significantly during operation. Under these conditions, the generator ensures high stability of output pulse energy and effectively uses energy that is reflected from the load. Using this generator, a high voltage generator with an output voltage pulse amplitude of ∼30 kV was developed. The high voltage generator is designed to be used in electric discharge technologies. The results of the experiments are given in which the high voltage generator produced discharges in water at a repetition rate of 500 Hz. The amplitude of the discharge current pulse was ∼600 A, and the pulse rise time was ∼150 ns.

Using the method of arterial piezopulsometry, statistical and spectral analyzes of variable parameters (VmaxPP and TNN) of pulse waves of blood pressure in patients aged 18 to 85 years were performed. The individual characteristics of the autonomous (vegetative and neuroendocrine) regulation of the muscular effectors (ME) of the cardiovascular system (CVS) in an elderly man (75 years old) and a young woman (20 years old) were estimated with high accuracy. These data, as well as the results of a comparative study of patients of different ages, made it possible to identify a certain pattern of directed change in the sympathoadrenal regulation of ME CVS in human ontogenesis. It is concluded that in the course of their lives, people undergo a restructuring of the physiological mechanism of the autonomous regulation of their ME CVS, aimed at replacing short-term sympathetic regulation in young people with more effective and more stable regulation by humoral catecholamines in elderly.С помощью метода артериальной пьезопульсометрии выполнены статистический и спектральный анализы вариабельных параметров (VmaxPP и TNN) пульсовых волн АД крови у пациентов 18–85 лет. С высокой точностью оценены индивидуальные особенности автономной (вегетативной и нейроэндокринной) регуляции мышечных эффекторов (МЭ) сердечно-сосудистой системы (ССС) у пожилого мужчины (75 лет) и молодой женщины (20 лет). Эти данные, а также результаты сравнительного исследования пациентов разного возраста позволили выявить определенную закономерность направленного изменения симпатоадреналовой регуляции МЭ ССС в онтогенезе человека. Сделан вывод, что у людей в процессе жизни происходит перестройка физиологического механизма автономной регуляции МЭ ССС, направленная на замену краткосрочной симпатической регуляции у молодых людей на более эффективную и устойчивую регуляцию гуморальными катехоламинами у пожилых людей.

The article reports the results of the analysis of the field prospecting activities of five exploratory wells at the Karmalinovskoye gas condensate field. We have found that the eastern part of the licensed area is characterized by the lack of fructuring in Paleozoic deposits, and the development of the productive deposit extends in the north-west direction. Hydraulic fracturing made it possible to get a stable gas and gas condensate flow rate in well № 4. This volume exceeds 3,8 times as large than flow rate in wells № 1 and № 2, which were tested after drilling without conducting hydraulic fracturing.

The results of investigations of silicon diodes in the mode of switching by nanosecond pulses, which initiate an impact-ionization wave, are presented. It is shown that the switching process is significantly influenced by dislocations that are formed in the surface layers of diode structures during their manufacture.

The results of investigations of new semiconductor devices, reverse switch-on dynistors dynistors–diodes (RSDDs), with an operating voltage of 2 kV and a 50-mm diameter of the structure are presented. Their comparison with conventional RSDs shows that the losses in RSDDs are approximately 2 times lower when high-power reverse-current pulses are switched, the losses are virtually the same during switching, and the losses are 15–20% higher when switching rapidly rising forward-current pulses. The limiting abilities of RSDDs are determined when switching unipolar current pulses with a duration of 300 μs: 30 and 100 kA in the reverse and forward directions, respectively. The possibility of reliable switching of alternating slowly damped current pulses with a duration of 40 μs and amplitudes of the first forward and reverse half-waves of 90 and 65 kA, respectively, with which conventional RSDs cannot operate, is shown.

The possibility of modifying the surface of film implants of porous fluoroplastic by treating them with a low-temperature plasma of a high-voltage discharge with a nanosecond duration was investigated. The specimens were films for reconstructive surgery (FRS) and films for the replacement of bone defects (FRBD) from polytetrafluoroethylene (PTFE). The duration of the plasma treatment of the specimens ranged from 1 to 10 s. The surface quality of the films was estimated by their roughness and hydrophilic behavior using an atomic force microscope. It has been found that the plasma treatment significantly increases the surface roughness, which is associated with a change in its structure. The degree of the hydrophilicity of the surface of the FRS and FRBD films was determined by the roll-off angle of a water droplet and depended on the initial state of the surface (the smooth or corrugated side of the specimen), the gas discharge gap width, and the duration of the plasma treatment. A correlation between the roll-off angle of a water droplet and the proliferative capacity of the cells that were inoculated was found: the larger the roll-off angle, the higher the density of the cells observed on the surface. It has been found that the plasma treatment hardly affects the mechanical strength of the films and ensures the sterility of the films for 28 days after the plasma treatment for 1 s.

The results of comparative investigations of assemblies of series-connected IGBT transistors (IRGPS60B120KD) with control circuits that are based on pulse transformers and ADuM21N microcircuits, which have a high insulation strength, are presented. The conditions for efficient switching of high-power current pulses with a submicrosecond rise time are determined. A small switch with an operating voltage of 12 kV that consists of two parallel-connected transistor assemblies is described. It provides switching of microsecond current pulses with an amplitude of 500 A and a rise time of 200 ns at a frequency of 100 Hz under natural cooling. The possibility of scaling the results is shown.

The possibility in principle is shown for rapidly and efficiently modifying the surface of medical articles made of polytetrafluoroethylene (PTFE) by placing them in a bulk plasma discharge formed in a highly overvoltage gap. As an example, by processing PTFE films with nanosecond discharges at a frequency of 3 kHz over a few seconds, it is possible to substantially improve the conditions for cytoadherence and increase the permeability of an implant, which is an important factor for its integration into adjacent tissues.

Ligation of the inferior vena cava (IVC) during classical orthotopic liver transplantation (OLT) may be followed by pronounced hemodynamic changes and may provoke renal dysfunction. The authors have examined the impact of IVC ligation during OLT without venovenous bypass grafting on early postoperative renal function in 6 patients. The Cockcroft-Gault formula was used to evaluate renal function from the creatinine clearance on postoperative days 1, 3, 7, and 10. The endogenous creatinine clearance was diminished within the first 24 hours after surgery; this was 68.2±18.1 (24.3—146) ml/min and significantly correlated with that before OLT, with the mean blood pressure (BPmean) in the icteric period, and with age. At the same time, icteric BPmean was in the normal range — 77.2±1.59 (71.6—81.6) mm Hg and clinical renal failure developed in a female patient with significant preoperative renal dysfunction. Thus, IVC ligation at OLT with IVC interposition in the study contributed to a lower endogenous creatinine clearance within the first 24 postoperative hours, but results in no clinical renal function aggravation.

Despite the fact that the key role of the liver in the formation of the immune response to injury is not in doubt, the mechanisms of weakening the immune response to infectious and noninfectious lesions in patients with hepatic failure remain unclear. We propose an original hypothesis of forming the ways to limit the amplitude of the systemic inflammatory response in patients with the end-stage liver disease. The basis of the hypothesis is the idea that as a result of reducing the intensity of the natural stimulation of membrane mCD14 receptors by the ligands of infectious nature, the basic mechanism of the systemic immune response induction by liver macrophages (Kupffer cells) is interrupted. According to the proposed hypothesis, in condition of liver failure, the synthesis of lipopolysaccharide-binding protein by hepatocytes is reduced. This leads to a decreased amplitude and intensity of the protective immune responses. This fact explains a number of clinical phenomena observed in patients with liver failure/dysfunction that consist in a reduced reactivity of the organism to the damage inflicted by infectious and noninfectious agents. The authors consider it possible to use this hypothesis in the search for new trends to prevent the immune system hyper-reactivity in sepsis, and to improve the therapeutic strategies for the management of patients at high risk of infectious complications after liver transplantation.

A high-voltage switch on the basis of a small unit of series-connected high-voltage integrated pulse thyristors (HVIPTs), which were developed at the Ioffe Physical Technical Institute, was designed and investigated. At a power voltage of 25 kV, current pulses of microsecond duration with an amplitude of 2.8 kA and a rise time of 0.8 μs were switched. The attained current density through an HVIPT (5.6 kA/cm2) appreciably exceeds the permissible current density for conventional thyristors. It is shown that the developed HVIPT unit can be used in the triggering circuit of a high-power assembly of reverse switch-on dynistors (RSDs) at an operating voltage of 25 kV, which consists of 14 series-connected dynistors with a diameter of their structures of 24 mm. The RSD switch with a triggering circuit on the basis of HVIPTs allowed switching of rapidly rising current pulses with an amplitude of 20 kA and a duration of 150 μs. The small dimensions of the HVIPT unit (4 × 10 × 32 cm) and the RSD assembly (7 × 7 × 34 cm) determine the wide prospects for using them in high-power pulse technology.

At the T(d, n)He4 reaction a neutron is accompanied by an associated alpha-particle emitted in the opposite direction. A time and a direction of the neutron escape can be determined by measuring a time and coordinates of the alpha particle at the position-sensitive alpha-detector. The nanosecond tagged neutron technology (NTNT) based on this principle has great potentialities for various applications, e.g., for remote detection of explosives. A spectrum of gamma-rays emitted at the interaction of tagged neutrons with nuclei of chemical elements allows identify a chemical composition of an irradiated object. For practical realization of NTNT, a time resolution of recording the alpha-gamma coincidences should be close to 1 ns. The total intensity of signals can exceed 1 × 106 1/s from all gamma-detectors and 7 × 106 1/s from the alpha-detector. The processing of such stream of data without losses and distortion of information is one of challenging problems of NTNT. Several models of analog DAQ system based on hardware selection of events were devised and their characteristics are examined. The comparison with the digital DAQ systems demonstrated that the analog DAQ provides better timing parameters, lower power consumption, and higher maximum rate of useful events.

The results of studying the switching capabilities of recently developed high-voltage integral pulse thyristors (HIPTs) with a working area of 0.45 cm2 and an operating voltage of 3 kV are presented. A silicon chip of a thyristor consists of a large number of microthyristor cells that are enabled strictly synchronously with a control-current pulse, thus providing low switching energy losses and allowing a current of up to 8 kA at a pulse duration of 1.5 μs to be switched within 500 ns in a single-pulse mode. The HIPT switching-off time is several microseconds when, after a power-current pulse terminates, a field-effect transistor with a low (tens of milliohms) channel resistance closes the emitter–base circuit. The low switching energy loss and the short switching-off time made it possible to use HIPTs in the mode of switching current pulses with an amplitude of 500 А at a frequency of 50 kHz.