Proceedings of the Bulgarian Academy of Sciences <p>Founded in 1948 by academician Georgy Nadjakov, "Comptes rendus de l’Académie bulgare des Sciences" is also known as "Доклади на БАН","Доклады Болгарской академии наук" and "Proceedings of the Bulgarian Academy of Sciences".</p> <p>If applicable, the name of the journal should be abbreviated as follows: C. R. Acad. Bulg. Sci. (according to ISO.)</p> <p><big><strong>Related subjects:</strong></big></p> <p class="condensed">Astronomy, Mathematics, Physics, Chemistry, Biology, Geology, Geophysics, Space Sciences, Engineering Sciences, Physical Geography, Medicine, Agricultural Sciences.</p> <p class="condensed">The manuscripts should contain only unpublished data in the respective scientific field. They can further be expanded to be published elsewhere. All manuscripts are subject to peer review and copy editing.</p> <p><strong><big>2002-2021 website:</big></strong></p> <p>The site with the archive of <em>Comptes rendus de l’Académie bulgare des Sciences</em> - 2002 to 2021 is <a href="" target="_blank" rel="noopener">still accessible at that address.</a></p> „Prof. Marin Drinov“ Academic Publishing House en-US Proceedings of the Bulgarian Academy of Sciences 1310-1331 <p>Copyright (c) 2022 Proceedings of the Bulgarian Academy of Sciences</p> <p>Copyright is subject to the protection of the <em>Bulgarian Copyright and Associated Rights Act</em>. The copyright holder of all articles on this site is Proceedings of the Bulgarian Academy of Sciences. If you want to reuse any part of the content, please, contact us.</p> A Version of the Hadamard–Lévy Theorem for Fréchet Spaces <div class="page" title="Page 1"> <div class="layoutArea"> <div class="column"> <p>We prove a version of the Hadamard–Lévy theorem for Keller $$C^1_c$$ mappings between Fréchet spaces.</p> </div> </div> </div> Kaveh Eftekharinasab Copyright (c) 2022 Proceedings of the Bulgarian Academy of Sciences 2022-08-31 2022-08-31 75 8 1099 1104 10.7546/CRABS.2022.08.01 Digital Image Filtering with New Generalized Order-k Jacobsthal Numbers <p class="p1"><span class="Apple-converted-space"> </span>In <span class="s1">t</span>h<span class="s1">i</span>s p<span class="s1">a</span><span class="s2">p</span>e<span class="s1">r</span>, a new <span class="s1">g</span>ene<span class="s1">rali</span>zed <span class="s1">or</span>de<span class="s1">r</span>-k <span class="s1">Ja</span>c<span class="s1">o</span>bs<span class="s1">t</span>h<span class="s1">a</span>l <span class="s1">a</span>nd <span class="s1">Ja</span>c<span class="s1">o</span>bs<span class="s1">t</span>h<span class="s1">al–L</span>uc<span class="s1">a</span>s <span class="s3">n</span>u<span class="s3">m</span><span class="s2">b</span>e<span class="s1">r</span>s <span class="s1">ar</span>e <span class="s1">i</span><span class="s3">nv</span>es<span class="s1">tigat</span>ed <span class="s1">a</span>nd used <span class="s1">i</span>n <span class="s1">t</span>he d<span class="s1">igita</span>l <span class="s1">i</span>m<span class="s1">ag</span>e p<span class="s1">r</span><span class="s2">o</span>cess<span class="s1">i</span>ng f<span class="s1">o</span>r fil<span class="s1">t</span>e<span class="s1">ri</span>ng <span class="s1">o</span>f <span class="s1">t</span>he <span class="s1">i</span>m<span class="s1">ag</span>e. The <span class="s1">Ga</span>uss<span class="s1">ia</span>n, M<span class="s1">or</span>ph<span class="s1">ologi</span>c<span class="s1">a</span>l <span class="s1">o</span><span class="s2">p</span>e<span class="s1">ratio</span>n w<span class="s1">it</span>h “M<span class="s1">otio</span>n”, M<span class="s1">or</span>ph<span class="s1">ologi</span>c<span class="s1">a</span>l <span class="s1">o</span><span class="s2">p</span>e<span class="s1">ratio</span>n w<span class="s1">it</span>h “<span class="s1">Di</span>s<span class="s1">k</span>” s<span class="s2">p</span>ecific<span class="s1">atio</span>n, <span class="s3">P</span><span class="s1">oi</span>ss<span class="s1">o</span>n me<span class="s1">t</span>h<span class="s2">o</span>d <span class="s1">a</span>nd <span class="s1">Ja</span>c<span class="s1">o</span>bs<span class="s1">t</span>h<span class="s1">a</span>l me<span class="s1">t</span>h<span class="s2">o</span>d <span class="s1">i</span>s used f<span class="s1">o</span>r <span class="s1">t</span>he fil<span class="s1">t</span>e<span class="s1">ri</span>n<span class="s1">g</span>. The S<span class="s1">tr</span>uc<span class="s1">t</span>u<span class="s1">ra</span>l s<span class="s1">i</span>m<span class="s1">ilari</span><span class="s3">t</span><span class="s4">y</span>, Mu<span class="s1">lti</span>sc<span class="s1">al</span>e s<span class="s1">tr</span>uc<span class="s1">t</span>u<span class="s1">ra</span>l s<span class="s1">i</span>m<span class="s1">i</span><span class="s1">lari</span><span class="s3">t</span>y <span class="s1">a</span>nd <span class="s3">P</span>e<span class="s1">a</span>k S<span class="s1">N</span>R <span class="s1">ar</span>e used f<span class="s1">o</span>r e<span class="s5">v</span><span class="s1">al</span>u<span class="s1">atio</span>n <span class="s1">o</span>f <span class="s1">t</span>he <span class="s1">r</span>esu<span class="s1">lt</span>s. <span class="s4">F</span><span class="s1">o</span>r <span class="s1">i</span>mp<span class="s1">l</span>eme<span class="s3">n</span><span class="s1">tatio</span>n <span class="s1">o</span>f <span class="s1">t</span>he p<span class="s1">ro</span><span class="s2">p</span><span class="s1">o</span>sed me<span class="s1">t</span>h<span class="s2">o</span>d <span class="s1">t</span>he M<span class="s1">atla</span>b <span class="s1">2021</span>a <span class="s3">v</span>e<span class="s1">r</span>s<span class="s1">io</span>n <span class="s1">i</span>s used.</p> Hossen Ahmed Ahmet Daşdemir Copyright (c) 2022 Proceedings of the Bulgarian Academy of Sciences 2022-08-31 2022-08-31 75 8 1105 1114 10.7546/CRABS.2022.08.02 Fog Climatology and Stability Index for Plovdiv 1991–2018 <div class="page" title="Page 1"> <div class="layoutArea"> <div class="column"> <p>Fog can cause large economic losses for public services and in particular aviation where the cost of flight delays and rescheduling is estimated to hundreds of millions of euros per year. Despite the continuous improvement of weather prediction fog diagnosis and forecasting remains a challenge. In the US alone, 74% of the fatal car crashes are associated with recorded low visibility but without fog warning in the forecast. Today the operational fog forecasting is mainly done with “in-house” developed tools, which is understandable due to the fog life cycle peculiarity. The aim of this work is to investigate the fog climatology for Plovdiv, Bulgaria, for the period 1991–2018 and to use it for calculation of a threshold value of stability index, which can be implemented as an operational forecast tool. One fog case in January 2013 is selected for numerical weather prediction simulations with the WRF model for the city of Plovdiv. It was found that while the index with its site specific threshold value describes well the fog evolution, the WRF model has large deviations in temperature compared to the observations during daytime.</p> </div> </div> </div> Nikolay Penov Guergana Guerova Anastasiya Stoycheva Copyright (c) 2022 Proceedings of the Bulgarian Academy of Sciences 2022-08-31 2022-08-31 75 8 1156 1164 10.7546/CRABS.2022.08.08 The Verification of Differentially Expressed Genes Related to Feather Colour in Quail Embryos by RT-qPCR Based on RNA-seq <div class="page" title="Page 1"> <div class="layoutArea"> <div class="column"> <p>Many differentially expressed genes associated with feather colour in quail embryos can be screened using RNA-seq technology. The aim of this study was to verify the accuracy of RNA-seq using RT-qPCR. The transcriptome of embryonic skin tissues of quails were sequenced by Illumina HiSeq TM2000 sequencing platform. As a result, 2512 differentially expressed genes were found. Among them, 950 differentially expressed genes were up-regulated in the skin tissues of white-feather quail embryos, and 1562 differentially expressed genes were down-regulated. The candidate genes were analyzed by RT-qPCR method to verify the accuracy and reliability of the RNA-seq. The results showed that the relative expression levels of ASIP and DDC in white-feather quails were significantly increased, while HOXD1, CTSD, KRT2, MBD2 and MT1 were significantly decreased, which was consistent with the results of RNA-seq. The validation results of the candidate genes can also provide some ideas to explain the difference in feather colour between maroon-feather quails and white-feather quails.</p> </div> </div> </div> Yunqi Hu Xiaohui Zhang Youzhi Pang Yanxia Qi Qiankun Wang Yiwei Zhao Zhiwen Yuan Tao Wang Linke Huo Shiwei Ren Copyright (c) 2022 Proceedings of the Bulgarian Academy of Sciences 2022-08-31 2022-08-31 75 8 1138 1145 10.7546/CRABS.2022.08.06 Examination of Exopolysaccharides from Porphyridium cruentum for Estimation of Their Potential Antitumour Activity in Vitro <div class="page" title="Page 1"> <div class="layoutArea"> <div class="column"> <p>Globally, research is being conducted focusing on new biologically active substances and technologies for their application in various sectors, in the hope that their biological and medical applications will be widely used in the next decade.</p> <p>The introduction of therapeutic agents of biological origin isolated from certain species of bacteria and algae and their potential for cancer treatment is based on their lower toxicity and hence greater safety compared to synthetic pharmaceuticals. In this respect, the potential of microbial producers and microalgae is enormous. Among the biologically active components isolated from algae of the greatest importance for biology and medicine are complex polysaccharides, as well as some pigments.</p> <p>In the present work, the antitumour properties of two fractions of polysaccharides from the red microalgae <em>Porphyridium cruentum</em> were observed by determining their effect on cell viability of four different cell lines.</p> <p>New data from the study indicate that samples treated with <em>P. cruentum</em> polysaccharide have significant and dose-dependent antiproliferative and cytotoxic effects. Changes in nuclear morphology in MCF-7 tumour cells induced by polysaccharide treatment, including chromatin condensation, nucleus fragmentation, and apoptotic body formation, have been demonstrated. Polysaccharides show obvious pharmacological effects in the treatment of tumour cells without side effects.</p> </div> </div> </div> Juliana Ivanova Angeliki Konstantinidou Lyudmila Kabaivanova Ani Georgieva Ivelin Vladov Svetlozara Petkova Copyright (c) 2022 Proceedings of the Bulgarian Academy of Sciences 2022-08-31 2022-08-31 75 8 1146 1155 10.7546/CRABS.2022.08.07 Tocopherol Content in Peanuts after gamma-Irradiation: Effect of Ascorbyl Palmitate Addition on Oil Stability <div class="page" title="Page 1"> <div class="layoutArea"> <div class="column"> <p>Food irradiation has a number of advantages over the other conventional preservation technologies like canning, freezing, pasteurization and addition of chemical preservatives. It is a fast and inexpensive treatment which can be performed in the original packaging eliminating the risk of re-pollution. Unfortunately, changes as a result of irradiation may occur in biologically active compounds, especially lipids and antioxidants, thus decreasing the oil oxidative stability. So, this study is focused on the evaluation of changes in the content of tocopherols in oil, extracted from peanuts subjected to <em>gamma</em>-irradiation with a dose of 10 kGy. The effect of ascorbyl palmitate added to the oil in different proportions has been studied as well. The results showed decreasing of tocopherols in the oil from irradiated peanuts. On the other hand, addition of ascorbyl palmitate in 1:1 ratio to the native γ-tocopherol indicated synergistic effect which not only compensated the negative effect of irradiation but decreased twice the oxidation rate compared to that of non-irradiated oil.</p> </div> </div> </div> Adriana Kazakova Michał Janiak Sabina Taneva Iskra Totseva Vessela Kancheva Ryszard Amarowicz Svetlana Momchilova Copyright (c) 2022 Proceedings of the Bulgarian Academy of Sciences 2022-08-31 2022-08-31 75 8 1123 1128 10.7546/CRABS.2022.08.04 Green Extraction of Antioxidants from Natural Sources with Natural Deep Eutectic Solvents <div class="page" title="Page 1"> <div class="layoutArea"> <div class="column"> <p>Natural deep eutectic solvents (NADES) have been developed in order to replace traditional volatile and toxic organic solvents for the extraction of biologically active substances from natural sources. Recent research has shown that NADES are able to retain and even improve the antioxidant properties of the molecules dissolved in them. The aim of the present study was to evaluate the antioxidant activity of the extracts of two medicinal plants, <em>Plantago major</em> and <em>Sideritis scardica</em>, and of propolis with 10 different NADES. The results obtained confirm that NADES extracts of medicinal plants and propolis have a good antioxidant potential, allowing obtaining natural antioxidants without the application of organic solvents. Because of the biocompatibility and low toxicity of the NADES, the opportunity to apply these extracts directly in formulations, such as cosmetics, food supplements, etc., seems promising.</p> </div> </div> </div> Hristo Petkov Boryana Trusheva Slaveya Krustanova Tsvetinka Grozdanova Milena Popova Kalina Alipieva Vassya Bankova Copyright (c) 2022 Proceedings of the Bulgarian Academy of Sciences 2022-08-31 2022-08-31 75 8 1129 1137 10.7546/CRABS.2022.08.05 Improved Cosmic Ray Spectrum and Intensity in Middle Atmosphere (CORSIMA) Model Considering Six Characteristic Energy Intervals <div class="page" title="Page 1"> <div class="layoutArea"> <div class="column"> <p>The new model CORSIMA (COsmic Ray Spectrum and Intensity in Middle Atmosphere) is presented in this study. Numerical determinations of the spectrum and intensity of Galactic Cosmic Rays (GCR) for the middle atmosphere and the lower altitudes of the ionosphere (30–80 km) are presented. These altitudes are above the Regener–Pfotzer maximum. The primary spectra of protons and helium (alpha particles) are used. According to the amount of particles, cosmic rays consist of 92% protons, 6% helium nuclei, 1% heavier elements, and 1% electrons (GINZBURG and SIROVATSKY [<sup>19</sup>]).</p> <p>We also use the approximation of ionization losses (Bohr–Bethe–Bloch formula) in six characteristic energy intervals, including the charge decrease interval for electron capture. In this way, the accuracy of the obtained results is improved.</p> <p>Analytical expressions for the contributions of the energy intervals are provided. An approximation of the ionization function on six energy intervals is used and the charge decrease interval for electron capture is studied. Numerical calculations are performed using computational algebra systems.</p> <p>The development of this research is important for a better understanding of the processes and mechanisms of space weather. The GCR affect the ionization and electrical parameters in the atmosphere and also the chemical processes (ozone formation and depletion in the stratosphere) in it. These effects can be significantly enhanced during strong and moderately strong solar proton events and geomagnetic storms.</p> </div> </div> </div> Peter Velinov Simeon Asenovski Lachezar Mateev Copyright (c) 2022 Proceedings of the Bulgarian Academy of Sciences 2022-08-31 2022-08-31 75 8 1165 1174 10.7546/CRABS.2022.08.09 Molecular Characterization of Service Tree (Sorbus domestica L.) Genotypes Selected from Tokat Province <div class="page" title="Page 1"> <div class="layoutArea"> <div class="column"> <p>This study was carried out to determine the genetic diversity of eleven service tree (<em>Sorbus domestica</em> L.) genotypes selected from Tokat province and taken under protection in the genetic resource plot. In the present study, ISSR-PCR studies were carried out on genotype DNAs obtained by Mini-CTAB method and the level of polymorphism between genotypes was determined us- ing seven UBC-ISSR primers. A total of 65 bands were obtained in service tree genotypes with seven primers and 56 of these bands were determined to be polymorphic. The number of bands obtained per primer varied between 5 and 12, the mean band number was 5.90, and the mean polymorphic band number was 5.09. The data obtained as a result of the evaluation of ISSR-PCR bands were analyzed in Popgene32 and MEGA5.0 computer package program, and a dendrogram was obtained according to the UPGMA method. In the dendro- gram obtained, it was determined that two groups were formed at the level of approximately 22% difference, and there was only one genotype in the small group while the other genotypes were in the large group.</p> </div> </div> </div> Oznur Atasever Sinem Erdem Copyright (c) 2022 Proceedings of the Bulgarian Academy of Sciences 2022-08-31 2022-08-31 75 8 1227 1233 10.7546/CRABS.2022.08.16 Evaluation of the Physiological and Behavioural Relationships of Yearling Bucks by Generalized Procrustes Analysis <div class="page" title="Page 1"> <div class="layoutArea"> <div class="column"> <p>The aim of this study is to evaluate the relationships between some sexual behaviours and physiological traits such as serum testosterone concentration, body weight loss and presence of horns of yearling bucks using Generalized Procrustes Analysis (GPA). In the study, 11 yearling bucks being sexually in- experienced were used. The sexual behaviours were determined with a total of four tests, which consisted of exposing the yearling bucks individually to three unrestrained estrous ewes for 15 min. In these tests, some behavioural characteristics such as number of ejaculations, flehmen response, number of mounts and serum testosterone concentration were determined. In the GPA analysis, the first two factors explained approximately 98% of the total variation between animals (Dimension 1 = 95.57%, Dimension 2 = 2.68%). It was determined that there was a positive and high correlation between tests and the number of mounts, which had a high correlation with the first dimension. Ejaculation frequency, flehmen response and testosterone levels decreased in line with in- creases in the number of mounts. As a result, it can be suggested that GPA can be effectively evaluated quantitative and qualitative behavioural characteristics without requiring any prior assumptions and reducing variability among animals.</p> </div> </div> </div> Serhat Karaca Gazel Ser Copyright (c) 2022 Proceedings of the Bulgarian Academy of Sciences 2022-08-31 2022-08-31 75 8 1234 1243 10.7546/CRABS.2022.08.17 Molecular Identification of Beauveria bassiana and Metarhizium anisopliae Isolates and Their Bio-control Potential against Acanthoscelides obtectus and Sitophilus Zeamais <div class="page" title="Page 1"> <div class="layoutArea"> <div class="column"> <p><em>Acanthoscelides obtectus</em> and <em>Sitophilus zeamais</em> are among the most damaging stored-product insect pests. This study was carried out to identify <em>Beauveria bassiana</em> and <em>Metarhizium anisopliae</em> and to evaluate their insecticidal potential against <em>A. obtectus</em> and <em>S. zeamais</em> adults. Fungal isolates were characterized molecularly based on ITS1, 5.8S and ITS2 regions of rDNA. <em>B. bassiana</em> YK23 and YK26, and <em>M. anisopliae</em> YK41 and YK45 were sprayed onto adults of <em>A. obtectus</em> and <em>S. zeamais</em> at 1×10<sup>5</sup>, 1×10<sup>6</sup> and 1×10<sup>7</sup> conidia mL<sup>−1</sup> doses. At the end of the 10th day of application, the numbers of dead adults were counted. Mortality rates (%) and lethal times (LT<sub>50</sub> and LT<sub>90</sub>) were calculated for each isolate. Fungal isolates displayed promising insecticidal activity against <em>A. obtectus</em> and <em>S. zeamais</em>. <em>B. bassiana </em>and<em> M. anisopliae</em> caused 100% mortality against <em>A. obtectus</em>, even at the lowest dose. However, <em>B. bassiana </em>and<em> M. anisopliae</em> caused 100% mortality on<em> S. zeamais</em> at higher doses. Depending on the increasing doses, significant decreases were observed at the lethal times. Median lethal time (LT<sub>50</sub>) decreased up to 64.24 h (2.67 days) and 53.69 h (2.24 days) in <em>A. obtectus</em> exposed to <em>B. bassiana </em>and<em> M. anisopliae</em>, respectively. LT<sub>50</sub> decreased to 61.04 h (2.54 days) and 53.89 h (2.25 days) in <em>S. zeamais</em> exposed to the same fungi. <em>B. bassiana </em>and<em> M. anisopliae</em> can be taken into account in the control of those pests.</p> </div> </div> </div> Salih Karabörklü Copyright (c) 2022 Proceedings of the Bulgarian Academy of Sciences 2022-08-31 2022-08-31 75 8 1244 1252 10.7546/CRABS.2022.08.18 Relevance of CMV DNA Detection in Symptomatic Children up to 3 Months of Age <div class="page" title="Page 1"> <div class="layoutArea"> <div class="column"> <p>Cytomegalovirus (CMV) is the most frequent cause of congenital infection worldwide. The burden of disease related to congenital CMV (cCMV) is substantial, as it is the leading cause of sensorineural hearing loss and an important cause of neurodevelopmental disabilities in children. Despite its clinical significance, cCMV infection often goes undetected because the majority of infected infants are asymptomatic at birth and screening programmes have not been implemented in any country.</p> <p>The aim of this study is to define the role of CMV in congenital and early postnatal morbidity in clinically relevant symptomatic children up to 3 months of age in Varna region, comparatively in ELISA (anti CMV IgM/IgG) and PCR.</p> <p>We found CMV DNA in 12 out of 50 tested children (24%, 95% CI: 12.16–35.84%). The viral load ranged in 65–1 628 879 IU/ml, average viral load 144 707.2 IU/ml.</p> <p>It is important to note that only half of the PCR positive children 6/12 (50%) had an anti CMV IgM positive result.</p> <p>Our data demonstrate that serological tests defining active CMV infection with CMV IgM detection are not sufficiently indicative in all newborns, and it is therefore mandatory to conduct modern PCR for all relevant infants after birth.</p> </div> </div> </div> Zhivka Stoykova Liliya Ivanova Diana Yordanova Snejinka Cvetkova Kalin Kalchev Copyright (c) 2022 Proceedings of the Bulgarian Academy of Sciences 2022-08-31 2022-08-31 75 8 1195 1201 10.7546/CRABS.2022.08.12 Tissue Oxygenation Measurement in Patients with Sepsis Compared to the Lactate Levels and Hemodynamical Monitoring <div class="page" title="Page 1"> <div class="layoutArea"> <div class="column"> <p>Near-infrared spectroscopy (NIRS) is a noninvasive method for measuring tissue oxygenation. The method allows for monitoring tissue perfusion in shock by revealing tissue hemoglobin oxygen saturation (StO<sub>2</sub>). The current study aims to compare tissue oxygenation levels with hemodynamical monitoring and lactate levels in patients in severe shock. Study encompasses 19 patients treated in intensive care unit (ICU) at Alexandrovska University Hospital. Ten of the patients cover the criteria for severe sepsis, the remaining nine patients have no data for septic condition. In both groups of patients tissue oxygenation levels measured with INVIOS monitor, mean arterial pressure (MAP), oxygen saturation in mixed venous blood (SvO<sub>2</sub>) and lactate levels within 72 h of intensive care unit admission are compared. The patients with severe sepsis have significantly lower levels of StO<sub>2</sub> in comparison with patients without sepsis. Tissue oxygenation levels correspond to the mean arterial pressure levels, oxygen saturation in mixed venous blood. StO<sub>2</sub> levels in the current study do not correlate significantly with the lactate levels in patients with sepsis. Near-infrared spectroscopy as StO<sub>2</sub> levels correlate with the hemodynamical monitoring in patients with severe sepsis, but do not correlate significantly with the severity of the disease. This data might indicate that tissue oxygenation monitoring has clinical significance in patients with sepsis. Further profound studies are necessary for assessing the role of tissue oxygenation monitoring in the early phase of resuscitation in septic patients.</p> </div> </div> </div> Ralitza Marinova Violeta Groudeva Plamen Krastev Copyright (c) 2022 Proceedings of the Bulgarian Academy of Sciences 2022-08-31 2022-08-31 75 8 1202 1209 10.7546/CRABS.2022.08.13 Ventricular Tachycardia Electrical Storm <div class="page" title="Page 1"> <div class="layoutArea"> <div class="column"> <p>The term “electrical storm” (ES) indicates a life-threatening clinical condition characterized by the recurrence of hemodynamically unstable ventricular tachycardia (VT) and/or ventricular fibrillation (VF). We are presenting a case of ES in hemodynamically unstable VT treated at pre-hospital and hospital level.</p> <p>Seventy-one-year-old patient with a previous history of hypertension, insulin-dependent diabetes, congestive stroke and myocardial infarction, severe three-vessel coronary artery disease and myocardial revascularization, diabetic nephropathy, chronic kidney failure, and chronic ischemic cardiomyopathy, collapses at home. After examination and diagnostic procedures, the emergency medical physician (EMS) diagnoses hemodynamically unstable VT, which he treats with medication and gets the patient urgently transported to a hospital. In the next 24 h, during hospitalization, there are five more separate episodes of VT with pulse treated with DC shock and antiarrhythmics. On the twelfth day of hospitalization, an implantable cardioverter-defibrillator is implanted to prevent sudden cardiac death. On the seventeenth day, the patient is discharged from hospital in stable condition.</p> <p>The question arises of further best pharmacological and non-pharmacological therapy of ES in hemodynamically unstable VT. It is necessary to educate EMS physicians in the practical application of synchronized cardioversion at the prehospital level.</p> </div> </div> </div> Jelena Kascak Sladjana Andjelic Gordana Teofilovski Copyright (c) 2022 Proceedings of the Bulgarian Academy of Sciences 2022-08-31 2022-08-31 75 8 1210 1218 10.7546/CRABS.2022.08.14 Pattern Electroretinography in Preperimetric Glaucoma <div class="page" title="Page 1"> <div class="layoutArea"> <div class="column"> <p>The aim of the study was to explore the informativeness of pattern electroretinography (PERG) as an objective method for detection of early changes in the retinal ganglion cells (RGCs) function in patients with preperimetric glaucoma. A group of 103 people was studied – 56 patients with preperimetric glaucoma and 47 healthy individuals as controls. Full ophthalmological examination, standard automated perimetry (SAP), optical coherent tomography (OCT) and PERG were performed. The main variables that were considered in the results analysis were the latency (L), amplitudes (A) and amplitude ratio (AR), reflecting the configuration of the wave forms. Statistical analysis was performed with IBM SPSS Statistics 23.0 statistical package. The comparative analysis between the PERG components values of patients from both groups demonstrated significant differences in L of P50 and N95 in central stimulation and in N95 in paracentral stimulation. L of the glaucoma patients were longer than those of the controls. In PERG A significant difference was found in component N35-P50 in central stimulation and in AR N35-P50/P50-N95 in paracentral stimulation. The PERG A of glaucoma patients were lower than those of the healthy subjects. These results correlated with the significant differences in the macular RNFL thickness between the two groups. PERG could be used as an objective method for registration of early changes in the RGCs function in glaucoma suspected patients before the presence of any functional changes in SAP and significant structural changes at OCT and also for monitoring the changes in dynamics.</p> </div> </div> </div> Elena Mermeklieva Copyright (c) 2022 Proceedings of the Bulgarian Academy of Sciences 2022-08-31 2022-08-31 75 8 1219 1226 10.7546/CRABS.2022.08.15 Electrical Conductivity of Composites from Polymer Poly(Ethylene Oxide) and Nematic Liquid Crystals E8 <div class="page" title="Page 1"> <div class="layoutArea"> <div class="column"> <p>The electrical conductivity of thin films (150 μm) of composites produced from polymer poly(ethylene oxide) (PEO) and nematic liquid crystals E8 (in compositional ratio PEO:E8 = 70:30 wt%) was studied by means of complex electrical impedance spectroscopy in the range from 1 Hz to 1 MHz. Both ion conductivity and alternating-current conductivity of PEO/E8 films were determined as depending on temperature in the room-temperature region 25–50<sup>◦</sup>C. The results show that the ion-conductive PEO/E8 composite is a promising material for electronic applications.</p> </div> </div> </div> Todor Vlakhov Yordan Marinov Georgi Hadjichristov Nicola Scaramuzza Copyright (c) 2022 Proceedings of the Bulgarian Academy of Sciences 2022-08-31 2022-08-31 75 8 1115 1122 10.7546/CRABS.2022.08.03 Langmuir Probes' Secondary Power Supply System for the "Obstanovka" Experiment and Plasma-wave Complex Aboard the Russian Segment of the International Space Station <div class="page" title="Page 1"> <div class="layoutArea"> <div class="column"> <p>The Plasma-wave complex is scientific instrumentation for plasma and wave parameters measurements in the vicinity of the International Space Station, and is implemented in the “Obstanovka” experiment aboard the Russian segment.</p> <p>The Langmuir probes instruments, developed at the Space Research and Technology Institute of the Bulgarian Academy of Sciences, measured the following parameters: electron temperature, electron and ion concentration, plasma and the International Space Station’s surface potential. One of the results is that sharp jumps in the surface potential are detected when crossing the terminator and the Equatorial anomaly.</p> <p>The Langmuir probes operate outside the Russian “Zvezda” module. Families of voltage-ampere characteristics of the Langmuir probe are measured – when the voltage changes in a certain range, the value of the current flowing is recorded.</p> <p>There are block and functional diagrams of the instrument Langmuir probes and its secondary power supply system, designed to supply the measuring probe, the analogue and digital circuit boards.</p> </div> </div> </div> Pavlin Gramatikov Boian Kirov Copyright (c) 2022 Proceedings of the Bulgarian Academy of Sciences 2022-08-31 2022-08-31 75 8 1175 1183 10.7546/CRABS.2022.08.10 Dynamic Problem for a Viscoelastic Hollow Cylinder with Coaxial Elastic Inclusion <div class="page" title="Page 1"> <div class="layoutArea"> <div class="column"> <p>A problem of non-stationary longitudinal wave propagation in the cross-section of an infinite hollow linear-viscoelastic cylinder with coaxial elastic inclusion is considered. On the contact surfaces between the layers, continuity of displacements and stresses is assumed. The solution of the problem is constructed using the integral Laplace transform in time with subsequent reversal. For the case when each of the relaxation kernels is a finite sum of exponentials, the original is presented as a series of residues. Thus, the process of constructing a non-stationary solution is reduced to the search for the roots of the characteristic transcendental equation. The derived solution allowed to investigate the transient wave propagation in a viscoelastic cylinder with coaxial elastic inclusion with specified initial data.</p> </div> </div> </div> Sergey Pshenichnov Marina Ryazantseva Radan Ivanov Maria Datcheva Copyright (c) 2022 Proceedings of the Bulgarian Academy of Sciences 2022-08-31 2022-08-31 75 8 1184 1194 10.7546/CRABS.2022.08.11