The Power Flow Angle of Acoustic Waves in Thin Piezoelectric Plates

The curves of slowness and power flow angle (PFA) of quasi-antisymmetric (A0) and quasi-symmetric (S0) Lamb waves as well as quasi-shear-horizontal (SH0) acoustic waves in thin plates of lithium niobate and potassium niobate of X-,Y-, and Z-cuts for various propagation directions and the influence of electrical shorting of one plate surface on these curves and PFA have been theoretically investigated. It has been found that the group velocity of such waves does not coincide with the phase velocity for the most directions of propagation. It has been also shown that S0 and SH0 wave are characterized by record high values of PFA and its change due to electrical shorting of the plate surface in comparison with surface and bulk acoustic waves in the same material. The most interesting results have been verified by experiment. As a whole, the results obtained may be useful for development of various devices for signal processing, for example, electrically controlled acoustic switchers

GEMINGA: NEW OBSERVATIONS AT LOW RADIO FREQUENCIES

ABSTRACT. After nearly 10 years, we have succeeded to detect radio emission from Geminga more again. In this report we present new evidence for presence of radio emission from Geminga in the range 42-112 MHz. The observations were carried out on two sensitive transit radio telescopes We used three new digital receivers to detect the pulses and to obtain dynamic spectra.The examples of mean pulse profiles are presented. Exact value of the dispersion measure have been calculated using the simultaneous observations at three frequencies

Эволюция методики и новые протоколы ультразвукового исследования легких при COVID-19 пневмониях

Competent triage of patients with COVID-19 pneumonia is not only about efficient allocation of hospital resources, but also about making timely decisions that can ultimately save the patient's life. When healthcare facility is overloaded, computed tomography to assess the severity of COVID-19-associated pneumonia in each individual case is not always possible. Alternative solutions, however, are opted.The aim of the study was to develop Lung UltraSound (LUS) protocols with high diagnostic potential for assessing the severity of pneumonia caused by COVID-19, which can be reliably used instead of CT during triage in an emergency setting.Materials and methods. We conducted a retrospective analysis of data on 161 hospitalized patients with confirmed pneumonia caused by COVID-19, subjected to both CT and LUS within 24 hours after hospitalization. Three consecutive LUS protocols, including two LUS developed by the NMHC (National Medical Surgical Center) authors, were tested to choose the most reliable protocol for assessing the severity of lung damage in pneumonia caused by COVID-19 (based on correlation with chest CT results). We also checked the applicability of LUS for the prognosis of the disease.Results. Moderate (50% CT) and severe (50% CT) lung damage can be distinguished when using both - the 16-zone and 12-zone LUS NMHC scanning protocols. The AUC for the ROC curves was almost identical: 0.83 (95% CI: 0.75–0.90 and 0.81 (95% CI: 0.73–0.88) for the 16-zone and 12-zone LUS NMHC protocols, respectively. The 16-zone LUS NMHC had an optimal threshold of 20 scores with a sensitivity of 67% and a specificity of 82%, while the 12-zone LUS NMHC provided an optimal threshold of 15 scores with the same sensitivity but lower specificity — only 73%. Neither the 16-zone nor the 12-zone NMHC LUS protocols could predict the outcome.Conclusion. The newly developed 16- and 12-zone LUS NMHC scanning protocols for patients with pneumonia caused by COVID-19 proved to be easy to implement, demonstrating a strong correlation with CT results. The 16-zone LUS NMHC protocol is probably more relevant for triage of patients with more than 50% of pulmonary tissue involvement based on CT data. Both protocols can be useful in emergency settings and in medical institutions with limited or no access to CT.Сортировка пациентов с COVID-19 пневмонией — очень зависимая от времени задача, которая позволяет эффективно распределить ресурсы больницы, что в конечном итоге может привести к спасению жизни пациента.Проблемы использования компьютерной томографии в перегруженной системе здравоохранения требуют поиска дополнительных методов дифференцировки тяжести пневмонии, вызванной COVID-19.Цель исследования — разработка протоколов ультразвукового исследования легких (Lung Ultra-Sound — LUS) с высокими диагностическими характеристиками для определения тяжести пневмонии, вызванной COVID-19, которые можно использовать вместо КТ во время сортировки в условиях неотложной помощи.Материалы и методы. Провели ретроспективный анализ данных о 161 госпитализированном пациенте с подтвержденной пневмонией, вызванной COVID-19, которым в течение 24 ч после госпитализации выполнили как КТ, так и LUS. Три последовательных протокола LUS, в том числе два, разработанные авторами LUS NMHC (National Medical-Surgical Center), тестировали, чтобы выбрать из них наиболее надежный для определения выраженности повреждения легких при пневмонии, вызванной COVID-19 (исходя из корреляции с результатами КТ грудной клетки). Проверили также применимость LUS для построения прогноза заболевания.Результаты. С помощью как 16-зонного, так и 12-зонного LUS NMHC протокола можно различать умеренное (50% по КТ) и тяжелое (50% по КТ) повреждение легких. AUC для кривых ROC была почти идентична: 0,83 (95% СИ, 0,75–0,90) и 0,81 (95% СИ 0,73–0,88) для 16-зонного и 12-зонного LUS NMHC протоколов, соответственно. 16-зонный LUS NMHC имел оптимальный порог 20 баллов с чувствительностью 67% и специфичностью 82%, в то время как 12-зонный LUS NMHC обеспечивал оптимальный порог 15 баллов с той же чувствительностью, но более низкой специфичностью — только 73%. Ни по 16-зонному, ни по 12-зонному LUS-протоколам NMHC нельзя было прогнозировать исход.Заключение. Недавно разработанные 16- и 12-зонные протоколы LUS NMHC для пациентов с пневмонией, вызванной COVID-19, оказались просто выполнимыми и имели сильную корреляцию с результатами КТ. 16-зонный протокол LUS NMHC вероятно более применим для сортировки пациентов, у которых по КТ имеется более 50% объема повреждения легких. Оба протокола могут быть полезны в условиях неотложной помощи и в медицинских учреждениях с ограниченным или отсутствующим доступом к КТ

Liquid Sensor Based on a Piezoelectric Resonator with a Lateral Electric Field Made of Piezo-Ceramics PZT

Поступила: 30.09.2019. Принята в печать: 10.10.2019.Статья является расширенной версией доклада, представленного на 29-й Международной Крымской конференции «СВЧ-техника и телекоммуникационные технологии» — КрыМиКо’2019 (Севастополь, РФ, 8–14 сентября 2019 г.).Received: 30.09.2019. Accepted: 10.10.2019.Экспериментально и теоретически исследовано влияние проводимости жидкости, контактирующей с пьезоэлектрическим резонатором с поперечным электрическим полем на основе пластины пьезокерамики ЦТС-19. В данном резонаторе поперечная компонента механического смещения, не приводящая к радиационным потерям при контакте с жидкостью, является превалирующей. Частотные зависимости реальной и мнимой частей электрического импеданса резонатора показали наличие трех резонансов на частотах 68,7, 97,8 и 264 кГц со значениями коэффициента электромеханической связи 12,2, 14,7 и 6,5 % соответственно. Добротность каждого резонанса при контакте с жидкостью оказалась существенно выше добротности резонатора c продольной акустической волной на основе ниобата лития. Были получены зависимости максимального значения действительной части электрического импеданса такого резонатора от проводимости жидкости. Проведен теоретический анализ влияния проводимости жидкости на характеристики резонатора.This paper demonstrates the results of the study of the sensor based on the resonator with the lateral electric field made of the ceramic PZT for measuring the conductivity of the contacting liquid. This sensor is made of the PZT ceramic plate of 3.54 mm thickness with shear dimension of 20×18 mm2.Two electrodes with the gap width of 4 mm are deposited on one side of the plate. The sensor features the 4 ml plexiglass container, the bottom of which is a resonator. The measured frequency dependences of the real and imaginary parts of the electrical impedance shows three resonances at frequencies of 68.7, 97.8, and 264 kHz. Aqueous solutions of sodium chloride are prepared with different conductivities in the range 3.2 – 9000 μS/cm. We have measured the frequency dependences of the real and imaginary parts of the sensor electric impedance with the liquid of different conductivity. The maximum value of the real part of the electric impedance monotonically decreases and reaches saturation for each resonance peak with increasing liquid conductivity. Theoretical analysis of influence of liquid conductivity on resonator impedance was also performed using equivalent circuit with two parallel branches. First branch included active and reactive resistors that corresponded to excitation of acoustic wave. The second branch includes the static capacitance of the resonator. We describe the presence of the conductive liquid by means of the leakage resistance connected with the capacitance in parallel. We underline that theoretical and experimental dependences are in a good agreement. Therefore the resonator with the lateral electric field based on the ceramic PZT shows high sensitivity to the changes in the conductivity of the liquid due to the high value of the coefficient of the electromechanical coupling. The sensor with liquid presence compared to the sensor made of lithium niobate with a longitudinal acoustic wave has a higher quality factor. We conclude that in the resonator made of piezoceramics, the shear component of the mechanical displacement is prevailing and does not lead to radiation losses.Работа выполнена при частичной финансовой поддержке грантов РФФИ № 19-07-00300, № 19-07-00304.This research is supported by grant No. 19-07-00300, No. 19-07-00304 from the Russian Foundation for basic research

Кровесберегающий эффект транексамовой кислоты при протезировании коленного сустава

Objective: to evaluate the efficacy and safety of tranexamic acid in knee joint replacement. Subjects and methods: the prospective open-label study of the efficacy of tranexamic acid as an agent for blood loss reduction in knee joint replacement included 41 patients who were randomly randomized in two groups. Tranexamic acid (Tranexam, ZAO «Mir-Pharm») was injected intravenously in a dose of 15 mg/kg in Group 1 patients just before tourniquet removal, which caused a significant (p=0.003) reduction in drainage losses (from 556 (200; 800) ml to 234 (100; 300) ml) and in the calculated (from the changed concentration on days 3—4 postoperative days) values of overall blood loss (from 1821 (1348; 2156) ml to 1269 (924; 1580) ml (p=0.001) in the immediate postoperative period. There were no tranexamic acid-associated complications. Conclusion: Tranexamic acid is an effective agent in reducing blood loss when the knee joint is replaced. Key words: knee joint replacement, blood loss, tranexamic acid.Цель исследования . Оценка эффективности и безопасности транексамовой кислоты при протезировании коленного сустава. Материал и методы. В проспективное открытое исследование эффективности транексамовой кислоты, как средства уменьшения кровопотери при протезировании коленного сустава, включены 41 пациент, рандомизированно распределенные в две группы. Пациентам первой группы непосредственно перед снятием турникета внутривенно вводили транексамовую кислоту (Транексам, ЗАО «Мир-Фарм») в дозе 15 мг/кг, что привело в ближайшем послеоперационном периоде к достоверному (р=0,003) снижению объема дренажных потерь [с 556 (200; 800) мл до 234 (100; 300) мл] и расчетной (по изменению концентрации гемоглобина на 3—4-е сутки после операции) величины общей кровопотери (с 1821 (1348; 2156) мл до 1260 мл (924; 1580); р=0,001). Осложнений, связанных с применением транексамовой кислоты не было. Заключение. Транексамовая кислота является эффективным средством уменьшения кровопотери при протезировании коленного сустава. Ключевые слова: протезирование коленного сустава, кровопотеря, транексамовая кислота

Прогностическая значимость моторных вызванных потенциалов при оперативных вмешательствах по поводу устранения спинального стеноза на цервикальном уровне

Introduction. Transcranial electrical stimulation is a neurophysiological method that is used intraoperatively for evaluating the conduct of a nerve impulse through the cortical-spinal tract. However, the results obtained during registration of this modality do not always correlate with the neurological status of the patient after surgery. The purpose of the study is to determine the prognostic significance of motor evoked potentials in surgical interventions for the elimination of spinal stenosis at the cervical level. Materials and methods. The study analyzed the results of 20 microsurgical root decompressions at the cervical level by eliminating spinal stenosis. Surgical interventions were performed in the neurosurgical Department of National medical and surgical center named after N.I. Pirogov from august 2018 to march 2019. Intraoperatively there were used the following modalities: motor evoked potentials, 3-channel registration of somatosensory evoked potentials from the median nerves, 8-channel electroencephalography, and train-of-four monitoring. The patients were divided into 2 groups: in the 1st group was used inhalant anesthetics, in the 2nd the anesthesia was conducted according to the protocol “Total intravenous anesthesia”. Results. Within each group, in a number of cases, there was a decrease in the response amplitude (by 80 % or more), as well as a loss of motor evoked potentials. In the “Total intravenous anesthesia” group, the current stimulation forces used to obtain motor evoked potentials did not exceed 150 mA, while in the group of inhaled anesthetics, the maximum value was 300 mA, and the average value was 170 mA. In the “Total intravenous anesthesia” group, in 2 cases, a loss of response from one myotome at the decompression phase was registered without recovery during intraoperation monitoring, in 2 cases there was the amplitude loss by 80 % or more with subsequent recovery. In the “Total intravenous anesthesia” group, the results were comparable. Conclusion. During neurophysiological monitoring in surgeries at the cervical level, the loss of motor evoked potentials from one myotome, as well as a decrease the response amplitude by 80 % or more are doubtful as a criteria for predicting neurological deficit.Введение. Транскраниальная электростимуляция – нейрофизиологический метод, который применяется интраоперационно и необходим для оценки проведения нервного импульса по кортико-спинальному тракту. Однако полученные результаты при регистрации этой модальности не всегда коррелируют с неврологическим статусом пациента при пробуждении. Цель исследования – определить прогностическую значимость моторных вызванных потенциалов при оперативных вмешательствах по поводу устранения спинального стеноза на цервикальном уровне. Материалы и методы. В исследовании проанализированы результаты 20 операций по микрохирургической декомпрессии корешков на цервикальном уровне путем устранения спинального стеноза. Оперативные вмешательства были проведены в нейрохирургическом отделении ФГБУ «Национальный медико-хирургический центр им. Н.И. Пирогова» с августа 2018 по март 2019 г. Интраоперационно использованы следующие модальности: моторные вызванные потенциалы, 3-канальная регистрация соматосенсорных вызванных потенциалов со срединных нервов, 8-канальная электроэнцефалография, контроль Train-of-four. По виду анестезиологического пособия пациенты разделены на 2 группы: в 1-й применялись ингаляционные анестетики, во 2-й – анестезиологическое пособие проводилось по протоколу Total intravenous anesthesia. Результаты. Внутри каждой группы в ряде случаев зафиксировано снижение амплитуды ответов (на 80 % и более), а также выпадение моторных вызванных потенциалов. В группе Total intravenous anesthesia применяемые для получения моторных вызванных потенциалов силы тока не превышали 150 мA, в то время как в группе ингаляционных анестетиков максимальное значение было 300 мA, среднее – 170 мA. В группе Total intravenous anesthesia в 2 случаях было зарегистрировано выпадение ответа с 1 миотома на этапе декомпрессии без восстановления за время мониторинга, в 2 случаях – падение амплитуды ответов на 80 % и более с последующим восстановлением. В группе десфлюрана результаты оказались сопоставимыми. Заключение. При проведении нейрофизиологического мониторинга при оперативных вмешательствах на цервикальном уровне выпадение моторных вызванных потенциалов с 1 миотома, а также снижение амплитуды ответа на величину 80 % и более сомнительны как предиктор неврологического дефицита

Gas Sensor Based on the Piezoelectric Lateral Electric Field Resonator and a Gas-Sensitive Chitosan Film

Поступила: 27.09.2019. Принята в печать: 10.10.2019.Статья является расширенной версией доклада, представленного на 29-й Международной Крымской конференции «СВЧ-техника и телекоммуникационные технологии» — КрыМиКо’2019 (Севастополь, РФ, 8–14 сентября 2019 г.).Received: 27.09.2019. Accepted: 10.10.2019.В работе исследованы сенсорные свойства датчика, представляющего собой структуру «стеклянная подложка – пленка хитозана – воздушный зазор – резонатор с поперечным возбуждающим электрическим полем (ПЭП)». Резонатор изготовлен из пластины пьезокерамики ЦТС-19 толщиной 2,54 мм и поперечными размерами 20×18 мм2 с двумя прямоугольными алюминиевыми электродами с размерами 20×7 мм2 и зазором между ними 4 мм. Полярная ось была ориентирована перпендикулярно зазору между электродами. В качестве газочувствительных пленок использовались пленки лактата хитозана и гликолята хитозана, сорбционные свойства которых изучались по отношению к парам воды, этанола и водного раствора аммиака (10 %). Установлено, что для обоих типов пленок в присутствии паров указанных жидкостей резонансная частота параллельного резонанса и максимальное значение реальной части электрического импеданса исследуемой структуры существенно уменьшаются и полностью восстанавливаются после удаления паров из камеры.We investigate the gas-sensitive properties of the sensor comprising “glass substrate – chitosan film – air gap – the lateral exciting electric field resonator (LFE)”. The resonator is made using a PZT-19 piezoceramic plate with a thickness of 2.54 mm and shear dimensions of 20×18 mm2 with two rectangular aluminum electrodes with dimensions of 20×7 mm2 and a 4 mm gap between them. The polar axis is oriented perpendicular to the gap between the electrodes. We use films of chitosan lactate and chitosan glycolate, as gas-sensitive films, whose sorption properties are studied in regard to water vapor, ethanol, and aqueous solution of ammonia (10%-wt.). It has been established that the resonance frequency of the parallel resonance and maximum value of the real part of the electrical impedance of the studied structures substantially have decreased for both types of films in the presence of vapors of the test analytes and have been completely restored after removing the vapor from the chamber.Работа выполнена при частичной финансовой поддержке гранта РФФИ № 19-07-00300.The research is completed with partial financial support of the RFBR grant No. 19-07-00300

Co-infection and ICU-acquired infection in COIVD-19 ICU patients: a secondary analysis of the UNITE-COVID data set

Background: The COVID-19 pandemic presented major challenges for critical care facilities worldwide. Infections which develop alongside or subsequent to viral pneumonitis are a challenge under sporadic and pandemic conditions; however, data have suggested that patterns of these differ between COVID-19 and other viral pneumonitides. This secondary analysis aimed to explore patterns of co-infection and intensive care unit-acquired infections (ICU-AI) and the relationship to use of corticosteroids in a large, international cohort of critically ill COVID-19 patients.Methods: This is a multicenter, international, observational study, including adult patients with PCR-confirmed COVID-19 diagnosis admitted to ICUs at the peak of wave one of COVID-19 (February 15th to May 15th, 2020). Data collected included investigator-assessed co-infection at ICU admission, infection acquired in ICU, infection with multi-drug resistant organisms (MDRO) and antibiotic use. Frequencies were compared by Pearson's Chi-squared and continuous variables by Mann-Whitney U test. Propensity score matching for variables associated with ICU-acquired infection was undertaken using R library MatchIT using the "full" matching method.Results: Data were available from 4994 patients. Bacterial co-infection at admission was detected in 716 patients (14%), whilst 85% of patients received antibiotics at that stage. ICU-AI developed in 2715 (54%). The most common ICU-AI was bacterial pneumonia (44% of infections), whilst 9% of patients developed fungal pneumonia; 25% of infections involved MDRO. Patients developing infections in ICU had greater antimicrobial exposure than those without such infections. Incident density (ICU-AI per 1000 ICU days) was in considerable excess of reports from pre-pandemic surveillance. Corticosteroid use was heterogenous between ICUs. In univariate analysis, 58% of patients receiving corticosteroids and 43% of those not receiving steroids developed ICU-AI. Adjusting for potential confounders in the propensity-matched cohort, 71% of patients receiving corticosteroids developed ICU-AI vs 52% of those not receiving corticosteroids. Duration of corticosteroid therapy was also associated with development of ICU-AI and infection with an MDRO.Conclusions: In patients with severe COVID-19 in the first wave, co-infection at admission to ICU was relatively rare but antibiotic use was in substantial excess to that indication. ICU-AI were common and were significantly associated with use of corticosteroids

Clinical and organizational factors associated with mortality during the peak of first COVID-19 wave: the global UNITE-COVID study

Purpose: To accommodate the unprecedented number of critically ill patients with pneumonia caused by coronavirus disease 2019 (COVID-19) expansion of the capacity of intensive care unit (ICU) to clinical areas not previously used for critical care was necessary. We describe the global burden of COVID-19 admissions and the clinical and organizational characteristics associated with outcomes in critically ill COVID-19 patients. Methods: Multicenter, international, point prevalence study, including adult patients with SARS-CoV-2 infection confirmed by polymerase chain reaction (PCR) and a diagnosis of COVID-19 admitted to ICU between February 15th and May 15th, 2020. Results: 4994 patients from 280 ICUs in 46 countries were included. Included ICUs increased their total capacity from 4931 to 7630 beds, deploying personnel from other areas. Overall, 1986 (39.8%) patients were admitted to surge capacity beds. Invasive ventilation at admission was present in 2325 (46.5%) patients and was required during ICU stay in 85.8% of patients. 60-day mortality was 33.9% (IQR across units: 20%–50%) and ICU mortality 32.7%. Older age, invasive mechanical ventilation, and acute kidney injury (AKI) were associated with increased mortality. These associations were also confirmed specifically in mechanically ventilated patients. Admission to surge capacity beds was not associated with mortality, even after controlling for other factors. Conclusions: ICUs responded to the increase in COVID-19 patients by increasing bed availability and staff, admitting up to 40% of patients in surge capacity beds. Although mortality in this population was high, admission to a surge capacity bed was not associated with increased mortality. Older age, invasive mechanical ventilation, and AKI were identified as the strongest predictors of mortality

Early mobilisation in critically ill COVID-19 patients: a subanalysis of the ESICM-initiated UNITE-COVID observational study

Background Early mobilisation (EM) is an intervention that may improve the outcome of critically ill patients. There is limited data on EM in COVID-19 patients and its use during the first pandemic wave. Methods This is a pre-planned subanalysis of the ESICM UNITE-COVID, an international multicenter observational study involving critically ill COVID-19 patients in the ICU between February 15th and May 15th, 2020. We analysed variables associated with the initiation of EM (within 72 h of ICU admission) and explored the impact of EM on mortality, ICU and hospital length of stay, as well as discharge location. Statistical analyses were done using (generalised) linear mixed-effect models and ANOVAs. Results Mobilisation data from 4190 patients from 280 ICUs in 45 countries were analysed. 1114 (26.6%) of these patients received mobilisation within 72 h after ICU admission; 3076 (73.4%) did not. In our analysis of factors associated with EM, mechanical ventilation at admission (OR 0.29; 95% CI 0.25, 0.35; p = 0.001), higher age (OR 0.99; 95% CI 0.98, 1.00; p ≤ 0.001), pre-existing asthma (OR 0.84; 95% CI 0.73, 0.98; p = 0.028), and pre-existing kidney disease (OR 0.84; 95% CI 0.71, 0.99; p = 0.036) were negatively associated with the initiation of EM. EM was associated with a higher chance of being discharged home (OR 1.31; 95% CI 1.08, 1.58; p = 0.007) but was not associated with length of stay in ICU (adj. difference 0.91 days; 95% CI − 0.47, 1.37, p = 0.34) and hospital (adj. difference 1.4 days; 95% CI − 0.62, 2.35, p = 0.24) or mortality (OR 0.88; 95% CI 0.7, 1.09, p = 0.24) when adjusted for covariates. Conclusions Our findings demonstrate that a quarter of COVID-19 patients received EM. There was no association found between EM in COVID-19 patients' ICU and hospital length of stay or mortality. However, EM in COVID-19 patients was associated with increased odds of being discharged home rather than to a care facility. Trial registration ClinicalTrials.gov: NCT04836065 (retrospectively registered April 8th 2021)