Supply Disturbances Research Articles

АКТИВНІСТЬ БІОЕНЕРГЕТИЧНИХ ПРОЦЕСІВ В ОРГАНІЗМІ ЩУРІВ, ОДНОЧАСНО УРАЖЕНИХ КАРБОФОСОМ І ТЕТРАХЛОРМЕТАНОМ, ПІСЛЯ КОРЕКЦІЇ МЕКСИДОЛОМ

Вступ. Потрапляючи в організм людини і тварин, фосфорорганічні речовини викликають активацію вільнорадикальних процесів, пригнічують захисно-компенсаторні сили, інгібують ензими, які беруть участь у процесах енергозабезпечення клітин. Тетрахлорметан, ксенобіотик, який використовують у промисловості, сільському господарстві та побуті, має токсичний вплив на печінку. В реальному житті нерідко трапляється комбінована дія декількох токсичних чинників, які, залежно від умов, можуть порушити рівновагу окиснювальних процесів в організмі та призвести до тяжких захворювань.
 Мета дослідження –вивчити інтенсивність процесів енергозабезпечення в організмі щурів за умов одночасного ураження їх фосфорорганічними сполуками і тетрахлорметаном, а також ефективність застосування при цьому антиоксиданта мексидолу.
 Методи дослідження. Дослідження проведено на білих щурах-самцях, яким щоденно протягом 30 днів вводили карбофос (20 мг/кг) і тетрахлорметан дворазово через добу (1 мл/кг). Тварин виводили з експерименту під тіопентал-натрієвим наркозом на 10 і 30 доби отруєння карбофосом та 4 і 7 доби після ураження тетрахлорметаном. У печінці та серці щурів визначали активність сукцинатдегідрогенази, цитохромоксидази та вміст глікогену, в сироватці крові – вміст глюкози.
 Результати й обговорення. Протягом усього експерименту спостерігали прогресуюче зменшення в печінці та міокарді уражених тварин активності сукцинатдегідрогенази та цитохромоксидази, яка до кінця дослідження виявилась найнижчою. Вміст глюкози в сироватці крові після ураження токсикантами максимально збільшився наприкінці експерименту. В цей же період відзначали максимальне зниження вмісту глікогену в печінці та міокарді уражених тварин. Застосування мексидолу призвело до підвищення активності мітохондріальних ензимів, а також нормалізувало вміст глюкози у сироватці крові та глікогену в печінці й міокарді уражених щурів, що підтвердило його антигіпоксантні властивості. 
 Висновок. Комбіноване ураження щурів тетрахлорметаном і карбофосом призводить до значних порушень в енергозабезпеченні органів тварин. Доведено ефективність застосування мексидолу як антигіпоксанта.

Synchronous Compensator Based on Doubly Fed Induction Generator to Improve the Power Quality under Unbalanced Grid Voltage Conditions

Currently, power quality is a major issue for all sorts of customers. End users of the electricity service in industrial, commercial and residential sectors have nonlinear loads or loads that are sensitive to disturbances in the electric power supply. In this context, this paper presents a study on four different control strategies for the application of synchronous compensator based on a doubly-fed induction generator (DFIG). The mathematical modeling developed to support the proposal of this article is validated through computational simulations and experimental results. This work contains strong arguments that support the idea that the proposed synchronous compensator can be employed to cancel oscillations caused by imbalances in the grid, and can furthermore inject or absorb reactive and active power without the characteristic oscillations that arise when negative sequence components are present in the system.

Fault signatures and bias progression in dissolved oxygen sensors.

Biofilm fouling is known to impact the data quality of sensors, but little is known about the exact effects. We studied the effects of artificial and real biofilm fouling on dissolved oxygen (DO) sensors in full-scale water resource recovery facilities, and how this can automatically be detected. Biofilm fouling resulted in different drift direction and bias magnitudes for optical (OPT) and electrochemical (MEC) DO sensors. The OPT-sensor was more affected by biofilm fouling compared to the MEC-sensor, especially during summer conditions. A bias of 1 mg/L was detected by analysing the impulse response (IR) of the automatic air cleaning system in the DO sensor. The IR is an effect of a temporal increase in DO concentration during the automatic air cleaning. The IRs received distinct pattern changes that were matched with faults including: biofilm fouling, disturbances in the air supply to the cleaning system, and damaged sensor membrane, which can be used for fault diagnosis. The results highlight the importance of a condition-based sensor maintenance schedule in contrast to fixed cleaning intervals. Further, the results stress the importance of understanding and detecting bias due to biofilm fouling, in order to maintain a robust and resource-efficient process control.

Monitoring responses to variation in food supply for a migratory waterfowl: American Black Duck (Anas rubripes) in winter.

Wintering Black Ducks (Anas rubripes) concentrate in wetlands along the Atlantic coast where natural and anthropogenic disturbances have increased over the last 50 years, a period in which the population of Black Ducks has declined. We studied the sensitivity of Black Ducks to perturbations in food supply that often result from disturbances by storms, predators, and people. In the paper, we characterize the responses of captive Black Ducks to shifts in food quality and availability during winter and apply those measures to a comparison of wild birds. Captive ducks that were fed intermittently (3 consecutive days/week) compensated for fasted days to achieve similar body mass and body fat to control birds that were fed every day on both animal- and plant-based diets. However, birds that were fed intermittently expended 15% more energy each day than controls when both groups were fed (536 vs. 464kJ/kg0.75), which indicates that variable food supply increases the costs of maintenance and thus reduces the number of birds that can be supported on the same resource of food without interruptions to foraging. Egg production was not affected by diet quality provided in spring or by the frequency of feeding during the preceding winter months. Black Ducks lost body fat through winter in captivity and in the wild. Fat stores of birds in New Jersey were greater than those of birds in Maine (13.3 vs. 8.3% of body mass) in January, which reflected the high energy demands of cold temperatures in Maine. Values for ∂15N were greater in Maine than in New Jersey for both red blood cells and plasma, which indicated a consistent diet of marine invertebrates in Maine. Greater isotopic variation in red blood cells indicated that diets were more diverse in New Jersey than in Maine for both ∂15N (9.7 ± 1.1 vs. 11.2 ± 0.4‰) and for ∂13C (- 15.1 ± 2.2 vs. - 13.8 ± 1.4‰). Plasma ∂13C was enriched over red blood cells in wild birds especially those with low fat stores, which suggested birds with low energy stores were shifting diets. Black Ducks can compensate for disturbances in feeding by increasing intakes if they have access to high quality wetlands where they are able to find abundant food. High energy demands at cold temperatures may constrain fat stores and thus the tolerance of feeding disturbances especially at the northern limits of the winter range. We hypothesize that decreasing variation in diet may indicate an increase in vulnerability to disturbance in winter when body fat is low. Recent efforts to assess and improve habitat quality of Black Ducks could be enhanced by monitoring the body composition and diet of birds to assess their vulnerability to disturbances in food supply and energy demands.

PATHOPHYSIOLOGIC MECHANISMS OF THE INFLUENCE OF TISSUE RESPIRATION ENZYMES ON THE MITOCHONDRIAL FUNCTION IN PATIENTS WITH CHRONIC HEPATITIS C

Studies conducted over several decades in the field of pathophysiological mechanisms of hepatocyte mitochondria have usually been directed to functional studies of isolated mitochondria in the absence of ADP. In many cases, researchers used data to calculate parameters, including the respiratory rate or the amount of ADP consumed for each amount of oxygen used. However, so far, little is known about how the virus can survive in a highly oxidizing environment, given that oxidative stress is such an outstanding clinical feature that is associated with infection with the hepatitis C virus. In our opinion, adaptation to oxidative stress is a pathophysiological mechanism for the survival of the virus. The objective is to research mechanisms of energy supply disturbance as a mechanism of damage to cells in patients with chronic viral hepatitis C. The 62 HCV+ patients and 24 healthy controls were enrolled in the present cross-sectional study. The patients were selected on the basis of their stable clinical condition over the past 3 months. The HCV infection was diagnosed by the positivity of anti-HCV and HCV-RNA for at least 6 months of period. Mitochondrial integrity was assessed by cytochrome C release using a commercial kit (Cytochrome C Oxidase Assay Kit, Sigma-Aldrich, St. Louis) indicating a mean of 96% intact mitochondria. Intrinsic NADH fluorescence was monitored in isolated mitochondria as a marker of the mitochondrial NADH redox state. Mitochondrial division is a key determinant of mitochondrial quality control, and HCV modulates these key processes in the adaptation to cellular physiological perturbations associated with infection to promote viral persistence. Mitochondrial division is not invariably associated with cell death but can also protect cells from death induced by oxidative stress and Ca2+-dependent apoptotic stimuli. The mechanism by which enzymes for energy metabolism suppress the replication of the hepatitis C virus is not yet clear, but it probably includes calcium and dissociation of the mammalian replication complex. A detailed understanding of the mechanism by which energy enzymes suppress the replication of HCV infection require additional research.

Investigating Environmental Impact Assessment (EIA) In Early Studies (Zero-Phase) to Prevent Delay in Operation of Construction Projects

Delay in project execution is one of the outmost problems that lead to delay to operation and subsequently, early structural erosion or financial supply disturbance, etc. Delay is fallen into several categories and each category has its own specific origin. However, in the present paper, environmental factors causing delay to projects are investigated. Delay to Construction Projects operation can be prevented by embedding environmental studies, namely environmental impact assessment (EIA) in initial studies. Given that environmental events cannot be predicted and we can only rely on statistic reports of previous periods, the effect of embedding such assessment in projects is so useful that every manger is convinced to make use of this assessment in study phase. The research results revealed that it is necessary to present EIA in initial studies to prevent delay to Construction Projects operation. In the following, given to the necessity of checklist, the quality of the designed checklist was investigated. Finally, the checklist was implemented and checked. In this study, each of the research questions was separately tested.

ЕКСПРЕСІЯ TAU-БІЛКУ В СЕНСОМОТОРНІЙ КОРІ ПРИ МОДЕЛЮВАННІ ТРАНЗИТОРНОЇ ІШЕМІЇ ТА ІМУНОКОРЕКЦІЇ

Вступ. Ішемія головного мозку супроводжується дифузним пошкодженням структурних елементів нейронів. Одним із маркерів, який демонструє функціональні процеси в нервовій системі, є tau -білок.Мета дослідження – вивчити особливості експресії tau-білку в сенсомоторній корі за умов порушення кровопостачання та корекції нейродегенеративних змін імуномодуляцією.Матеріали і методи. При моделюванні транзиторної ішемії та корекції нейродегенеративних змін імунофаном, був проведений експеримент на 150 білих статевозрілих щурах-самцях масою 260–290 г. Були застосовані гістологічні, імуногістохімічний, морфометричний та статистичний методи дослідження.Результати. Проведені спостереження показали, що порушення кровообігу у корі мозку призводять до зростання експресії tau-білку в сенсомоторній корі. Виразність цих змін залежить від ступеню порушення кровообігу, що непрямим шляхом підтверджується наявністю змін експресії tau-білку в контрлатеральній півкулі.Стрімке наростання експресії tau-білку в гостру фазу після ішемічної атаки свідчить про дезорганізацію цитоскелету нервових волокон та, певною мірою, відображує явища аутонейротомії. Поява tau-білку в перикаріонах нейроцитів може бути показником тяжкості дегенеративних процесів. Виявлення tau-білку в тілах гліоцитів може бути розцінені як явища фагоцитозу продуктів розпаду.Застосування імунофану, який має певний нейропротекторний ефект, показало його здатність зменшувати індуковане ішемією підвищення експресії tau-білку. Це може бути пояснено як імунорегулюючими властивостями цього пептиду (аргініл-альфа-аспартил-лізил-валіл-тирозил-аргінін), так і його детоксикаційною дією, блокуванням вільнорадикальних процесів перекисного окиснення, запобіганням пошкодженню лімфоцитів та гранулоцитів, що приймають участь у нейрозапеленні .Висновки. Транзиторне порушення кровопостачання сенсомоторної кори великих півкуль призводить до зростання в ній експресії tau-білку, повного відновлення якої не відбувається навіть через 3 місяці після ішемічної атаки. Дисциркуляторні зміни у мозку, що виникають при мобілізації або перев’язуванні сонної артерії з боку операції, а також ті що виникають у контрлатеральній півкулі мозку, призводять до незначного, але на певному етапі, статистично значущому підвищені експресії tau-білку.Застосування імунофану при порушенні кровопостачання мозку призводить до менш виразного зростання експресії tau-білку в сенсомоторній корі.

The use of the osteopathic correction for the combined treatment and rehabilitation of the patients presenting with the vertebral artery syndrome

The pathological changes in the cervical spine frequently result in the disturbances of the blood supply in the vertebral-basiliar system. The degenerative-dystrophic processes in the cervical spine occupy the leading place in the pathogenesis of the vertebral artery syndrome (VAS) causing disorders of the microcirculation and innervation, as well as the restriction of mobility and the development of somatic dysfunctions. It can be assumed that the manual methods applied to manage this condition can be effective in the removal the functional abnormalities in the blood flow. The objective of the present study was to evaluate the effectiveness of the osteopathic treatment as a component of combined therapy of the patients presenting with the vertebral artery syndrome. This experimental prospective controlled randomized study was conducted during the period from January 2015 till January 2017. A total of 106 patients with VAS, aged from 20 to 60 (the average age was 43.1±1.0 years) took part in the study. The patients were divided into three groups. The experimental group was comprised of 40 patients who received the medicamentous and osteopathic treatment. The control group consisted of 40 patients given the medicamentous treatment alone. The group of comparison contained 26 patients treated with the use of pharmacotherapy and massage. The methods finding application in clinical neurology, clinical osteopathy, and ultrasonic diagnostics of the brachiocephalic vessels were employed to evaluate the health status of the patients and evaluate the effectiveness of their treatment. The combined treatment of the patients comprising the experimental group with the use of osteopathic correction and pharmacotherapy produced the positive effect and resulted in the normalization of the neurological status of the patients; specifically, the incidence of both subjective and objective (neurological) symptoms was reduced. Simultaneously, the incidence of somatic dysfunctions at all levels of their manifestation decreased as compared with their frequency in the patients of the control and comparison groups. The results of the ultrasound examination of the great vessels of the neck and the brain in the experimental group made possible the evaluation of the dynamics in the incidence of the major pathological changes in the vessels of the vertebral-basiliar basin (VBB). It was shown that the occurrence of such serious changes as venous dishemia, reduction of the vasoconstriction and vasodilation reserves in VBB, in the patients of the experimental group vessels fell down by 32.1% (p<0.001), in comparison with only 12% (p<0.05), in the control group and 6,27% in the group of comparison (p>0.05). The osteopathic manipulative treatment included in the combined therapy of patients with VAS based on the personified approach to the management of individual cases, detection and correction of each clinically significant functional disorder accompanying the pathological process greatly contributes to the regression of the neurological symptoms, elimination of somatic dysfunctions at different levels of the body, normalization of the blood flow in the vessels of the vertebral-basilar system. Taken together, these effects prolong the beneficial results of the combined rehabilitative treatment of the patients with the vertebral artery syndrome based on the application of standard pharmacotherapy and correction of the functional disorders with the use of the osteopathic methods.

Complications after toe-to-hand transfers in children with pathologies of the hand

Background. Complications after microsurgical toe-to-hand transfer is a problem for which there is no common approach to treatment.&#x0D; The aim of this study was to analyze the ischemic complications after microsurgical operations in children with pathologies of the hand to improve the quality of surgical treatment.&#x0D; Materials and methods. From 2007 to 2016, we performed 210 microsurgical toe-to-hand transfers involving 306 transplants, 267 (87.3%) of which were performed in patients with congenital pathologies and 39 (12.7%) in patients with post-traumatic deformities of the hand. In total, 352 fingers were reconstructed.&#x0D; Results. Blood supply disturbance following toe transplants occurred in 19 (6.2%) of the 306 transplants, most often in the early postoperative period (73.7%). The main cause of microcirculatory disorders was thrombosis of the venous or arterial trunks (8 cases). In 6 patients, the blood supply disturbance occurred because of thrombosis of autovenous grafts. Two patients underwent necrectomy at days 7 and 18 because conservative and operative treatments were not successful.&#x0D; Conclusion. The treatment method of choice after the first appearance of signs of blood supply disturbance in a transferred toe is conservative therapy, which includes disaggregants, anticoagulants, and hirudotherapy. Conservative therapy should be performed within 3 hours from the beginning of ischemia; if ischemia is absent, the patient must undergo surgery. The operation includes soft tissue decompression, mechanical pumping across vascular anastomoses, and if necessary, excision of the abnormal vessel part with subsequent autoplasty.

EPIDEMIOLOGY OF STROKE IN BISHKEK ACCORDING TO THE REGISTER

Using a register approach, an epidemiologic survey of stroke in Kyrgyzstan (Bishkek) was conducted according to a program specially worked out. A total sample studied included 567218 subjects. Overall, 3200 new cases of acute blood supply disturbances were registered for a two- year period. Stroke morbidity was found to reach 2.82 per 1000 persons, mortality rate – 1.18, lethality – 41.8%. 42.4% patients were admitted to the hospital, in these cases mortality was 25,7%, while that in patients with stroke were treated –53.6%. It is concluded that a longitudinal register for obtaining data on mortality dynamics and evaluation of efficacy of improved medico- social care programs is needed.

THE ROLE OF MORPHOLOGICAL STUDIES OF PLACENTA IN DIAGNOSIS OF INTRAUTERINE INFECTIONSOF NEWBORNS

Introduction. Infectious disorders of the afterbirth (or placenta) are now of frequent occurrence, and have specific morphologic manifestations, which significantly affects the course of pregnancy, childbirth, intrauterine growth and development and postnatal health of the infant.The purpose of the study was to optimize the diagnosis and prognosis of the severity of intrauterine infection in neonates based on an assessment of risk factors, perinatal history and the results of morphological studies of afterbirth of those mothers, who had children with intrauterine infection.Materials and methods. Clinical and laboratory examination of 834 mothers and their diseased newborns suspected to have intrauterine infection the first 3 days of life was performed. The subject of in-depth study was a group of 224 patients with newborns with congenital infections. The control group consisted of 30 apparently healthy newborns. Confirmation of intrauterine infection was conducted based on history, physical exam data, and standard tests and using morphological studies of the born placenta.Results of the study. Among the total number of examined newborns, intrauterine infection was verified in 708 (84.9%) patients. The subject of the in-depth study was a group of 224 (31.6%) diseased newborns with congenital viral infections. Among them were term infants - 132 (58.9%) and premature babies - 92 (41.1%). Among 224 children, 77 (34.4%) mixed viral infections, 62 (27.7%) viral and bacterial infections, 53 (23.6%) mixed viral TORCH infections with monoviral infections - in 32 (14.3%). Among the risk factors, acute respiratory viral infections predominate in pregnant women (45.5%), threatening miscarriage (43.7%), anemia of pregnancy (25.0%), preterm delivery (41.1%), placental dysfunction 23.2%), preeclampsia (17.4%), asphyxia of newborns (40.6%). Analyzing the results of a histological study of 224 placentas in women who gave birth to children with congenital viral infections we revealed that in addition to specific morphologic changes caused by respiratory viruses, 54 (24%) also manifested non-specific inflammation(deciduitis, villusitis) and diverse variants of altered placental circulation. It confirms that in addition to the direct harmful effect of the virus, the secondary hypoxia and fetal supply disturbance can occur. The absence of specific signs and symptoms of viral infections in pregnant women does not exclude the need to investigate the afterbirth of children at risk to have intrauterine infection.Conclusions. The results of the histological examination of the placentas substantiate both the etiology of congenital viral infections based on specific morphological features, as well as the effect of nonspecific inflammatory changes (basal deciduitis, vylusitis) and variations of transplacental circulation disturbances on prediction the severity of congenital viral infections in newborns.

Swept-source OCT and swept-source OCT angiography in glaucoma diagnostics

Swept-source OCT (SS-OCT) has been introduced as a fast method for examining the retinal nerve fiber layer (RNFL) and, like OCT angiography (OCTA), the structure of vessels in the retina and the optic nerve head. The aim of this study was to assess whether SS-OCT is able to detect different patterns of glaucomatous nerve fiber layer defects and to evaluate OCTA measurements in the same areas. SS-OCT and OCTA data of glaucoma patients who were examined in the glaucoma unit of the Evangelisches Krankenhaus Gelsenkirchen between 2016 and 2017 were evaluated. In SS-OCT, a variety of signs indicating glaucomatous nerve fiber layer defects could be described, which corresponded to vessel defects, mainly of the small vessels and capillaries in OCTA. Samples are described in detail. SS-OCT is able to detect different patterns of glaucomatous nerve fiber layer defects making it a helpful tool in glaucoma diagnostics. Most frequently, OCTA measurements show similar patterns of capillary rarefication indicating blood supply disturbances in these areas, too. Patients with more advanced OCTA damage may need additional internal and neurological work-up especially when the IOP is normal. Future studies with SS-OCT and OCTA at different stages of glaucoma and with long-term follow-up may provide new insight into the pathogenesis and course of the disease.

POTENTIAL ROLE OF INTRAVITAL ARTERIAL EMBOLOGENIC THROMBI ON CARDIO-VASCULAR CATASTROPHIC EVENTS ACCORDING TO POSTMORTEM INVESTIGATIONS

Aim. The purpose of our study was to value the role of potential arterial emboli sources in death cause according to postmortem data collected in deceased from all causes in a multifield hospital.Material and methods. We performed retrospective analysis of 1324 postmortem records of died pa- tients for the past 6 years (2011-2016). We registered patients’ age and sex, thrombus site, definite intravital clinical and anamnestic data, individual features of tanathogenesis.Results. Intravital thrombus formation was found in 64 of died patients (4,8%), mean age 73,9±2,7 years, women 51,5%. In 41 patients (1 group) there were firm wall thrombi in aorta, in 23 patients thrombi were found in heart cameras (2 group), mostly in left atrial appendage (LAA). Generalized atherosclerosis presented more often in 1 group - 95,5% vs 39,1 in 2 group (p&lt;0,005). The most com- mon cause of death in both groups was acute myocardial infarction. In 1 group infarction was often in combination with acute blood supply disturbances in various arterial regions. For deceased of 2 group thromboembolic fatal events were more typical.Conclusion. It was found that the most dangerous thrombi regarding thromboembolic events were intracardiac ones, mainly in LAA. Aortic wall thrombi have become the marker of generalized athero- sclerosis. The last ones predetermined high probability of ischemic complications in multivessel areas.

An Improved Scheme for Voltage Sag Override in Direct Torque Controlled Induction Motor Drives

This paper analyses symmetrical and unsymmetrical voltage sag effects on the torque and speed deviation in direct torque controlled (DTC) induction motors (IMs) for adjustable speed drives (ASDs). The capability of an ASD for continuous normal operation in case of short supply disturbances is essential for high performance drives. In this paper, an updated scheme is proposed for boosting ASD performances during supply disturbances with voltage reduction. Flux weakening is an effective method to overcome the torque-decreasing problem in case of DC-link voltage diminishing. It is also shown that speed reduction is an efficient procedure to obtain the voltage sag insensitivity of an ASD, which is appropriate for the existing industrial applications. Extensive laboratory testing has been conducted to verify the performances and effectiveness of the proposed control algorithm. The suggested method requires only a modification of converter control software or operating speed change without any additional hardware components. Extended tests under various voltage sags events were carried out on a 1.5 kW laboratory drive, and the obtained results have been compared with an industrial DTC drive.

Multi-criteria analysis of district heating system operation strategy

The contemporary energy system is faced with new challenges on the energy market. Both the rising share of renewable-based electricity (characterised by intermittent production) and increasing energy efficiency in buildings induce a reconsideration of the traditional role of conventional power plants coupled with district heating systems along with its impact on the energy system. Moreover, the price of electricity determined by the merit-order system additionally decreases the load factor of such plants, making them less competitive or even inflicting financial loss in operation. Research presented in this paper focuses on a novel approach towards conventional combined heat and power (CHP) plants coupled with district heating systems. It involves an analysis of dynamical performances of the district heating system – capability of energy accumulation and thermal inertia – in order to assess its potential to become part of ancillary services. It is concluded that the district heating system, i.e. network of pipelines can be considered as dynamical thermal energy storage in which excess energy can be stored during operation of the CHP plant. A comprehensive analysis of dynamic behaviour of the district heating system has been performed by means of a mathematical model developed as a part of this research. The model is implemented on a theoretical case consisting of a simplified district heating system with three final users and the pipeline network of 9000m in length. The simulation has shown that the storage capacity of the network depends on the thermal load in the network and in such circumstances specific thermal capacity of the network amounts to 10.1Wh/(km). If the thermal load is decreased by 13% at the peak the accumulation capability is decreased by 40%. Moreover, the thermal capacity of the network increases up to 13.7Wh/(km) as the pipeline length declines to 1000m which is characteristic of densely populated areas. The capability of energy accumulation is explored for different parameters, such as: external temperature, distance of the network, supply water temperature etc. It is shown that distance of final users from CHP plant has certain impact on the operation strategy as well. Final users closer to the CHP plant determines operation strategy in the case of short-term disturbances in heat supply, while the farther ones in the case of long-term disturbances.

Reactions of Microglial Cells in the Sensorimotor Cortex of Rats after Transient Ischemia

Blood supply disturbances in the cortex after carotid ligation or microembolization of the vessels of the hemisphere by adipocytes result in an increase in the number of Iba-1+ microgliocytes in the hemisphere; the intensity of such increase depends on the degree of ischemic damage. The reaction of microglia to this damage shows a systemic character, since it is also manifested in cortical parts that did not directly undergo destructive (necrotic) changes and were beyond the zones of ischemization. An immunomodulator, Immunofan, increased the number of Iba-1+ microgliocytes within the acute period after transitory ischemia; within the recovery period, their number significantly decreased. This coincided with the more favorable time course of the postischemic process as a whole. The latter phenomenon can be considered a manifestation of the neuroprotective properties of Immunofan.

A New Structure of Dynamic Voltage Restorer Based on Asymmetrical 􀄫-source Inverters to Compensate Voltage Disturbances in Power Distribution Networks

As a consequence of sensitive, diverse and complex loads in today's distribution networks, improving power quality in distribution systems has attracted great attention. Power quality issues involve voltage sags, transient interrupts and other distortions in sinusoidal waveforms. Enormous methods have been proposed for power quality modification. One of the methods by which power quality problems might be addressed is to apply power electronic devices in the form of custom power devices. One of such devices is Dynamic Voltage Restorer (DVR) which is connected in series to distribution networks. At the same time, through injection of voltage to the network it is able to control voltage amplitude and phase. It is adopted lend to compensate for voltage sags through injecting series and synchronous three phase voltage. Consisted of three single phase inverters and a DC bus, it can protect susceptible loads against various types of voltage sags as well as other disturbances in the power supply. Moreover, it is capable of generating and absorbing active and reactive power. Therefore, in this paper, different structures of DVR have been investigated and eventually proposed a new structure for DVR based on Γ-Source asymmetric inverter. With the proposed structure, severe voltage sags can be retrieved 80- 90 percent. The simulation results that obtained by using MATLAB/Simulink indicate the properly functioning of proposed structure.

Energy Security as a Priority for CEE Countries. Is the King Naked?

The aim of this article is to assess the implementation process of the EU energy security policy in Central and Eastern European (CEE) countries. In the EU, energy security remains a crucial issue for European Energy Strategy, the fundamental goals of which include the security of supply, sustainability and competitiveness. Security of supply should be considered the most important aspect in this context, because it is connected to deep interdependencies between markets and economies, often based on political or even geo-political considerations. This is currently particularly noticeable, among other things, in the relations between the EU and Russia, where – in the event of any potential energy supply disturbances – some CEE countries are considered to be the most exposed. By analysing matters referred to the security of energy supplies, the article aims to determine the scope of activities undertaken by selected CEE countries which are also EU Member States in order to achieve this goal. The paper stresses the significance of cooperation by CEE countries at regional level, and focuses on initiatives and projects meant to ensure the security of their energy supplies. The conclusions of the paper assess some of the success stories as well as failures experienced by CEE countries in the process of building their energy independence.

Single‐phase solar PV system with battery and exchange of power in grid‐connected and standalone modes

A grid tied photovoltaic (PV) power conversion topology is presented in this study with a novel scheme of re-synchronisation to the grid. This scheme serves the purpose of supplying continuous power to the load along with feeding power to the grid. The control approach helps in mitigation of harmonics and improving the power quality while extracting the optimum power from the PV array. Depending on the availability of grid voltage, the proposed configuration is controlled using three approaches, defined as grid current control, Point of Common Coupling (PCC) voltage control and intentional islanding with re-synchronisation. A simple proportional integral controller manages the grid current, load voltage, battery current and DC Direct Current (DC) link voltage within these modes. Moreover, a control scheme for quick and smooth transitions among the modes is described. The robustness of the system under erratic behaviour of solar insolation, load power and disturbances in grid supply makes it a suitable choice for a residential application. The control, design and simulation results are presented to demonstrate the satisfactory operation of the proposed system.

DOPLEROGRAPHIC DESCRIPTION OF RENAL BLOOD SUPPLY DISTURBANCE IN PATIENTS WITH CHRONIC KIDNEY DISEASE STAGE I-II AND ARTERIAL HYPERTENSION

The purpose of this work was to investigate renal blood supply disturbance in patients with chronic renal disease stage I-II (pyelonephritis, glomerulonephritis, diabetic nephropathy).&#x0D; Material and methods. The authors carried out 131 complex ultrasonic investigations using ultrasonic duplex color kidney scanning. 47patients with chronic pyelonephritis (ChPN), 48patients with diabetic nephropathy stage IV (DN) and 36patients with chronic glomerulonephritis (ChGN) were involved into investigation. Each group consisted of 2 subgroups – with arterial hypertension (AH) and without AH. 20 healthy persons were examined as well.&#x0D; Results. Scantyintrarenal blood flow which is characterized with a decrease of maximal systolic (Vs), minimal diastolic blood velocity(Vd), as well as a decrease of indices of the averaged, according to time, maximal blood velocity (TAMX) and volumetric blood velocity (Vvol) and an increase of index resistance (IR) have been revealed in patients with chronic renal disease (ChRD) stage I-II with the presence of AH stage II. Indices of the vascular renal blood flow under study correlated with the main factors of ChRD progression – glomerular filtration rate (GFR) and daily proteinuria.&#x0D; Conclusion. Reliable Vs, Vd, TAMX and Vvol decrease and a reliable IR increase may be considered as early noninvasive criteria of ChRD progression with the presence of AH stage II.