К вопросу об оздоровлении воздуха в пассажирских вагонах (1891–1892 годы)

News from the archivesThis material briefly reproduces the main content of the article by Alexander Kritsky in the «Railway Business» journal in 1891 and 1892. The very fact of a multi-issue and very voluminous publication shows how much attention was paid at one time to the issue of air purity in railway passenger cars.The original punctuation, vocabulary and abbreviations adopted at that time are preserved in the text as much as possible.Пресс-архивДанный материал кратко воспроизводит основное содержание статьи А. М. Крицкого в журнале «Железнодорожное дело» в 1891 и 1892 годах. Сам факт растянувшейся на несколько номеров и весьма объёмной публикации показывает, какое внимание было уделено в своё время вопросу чистоты воздуха в железнодорожных пассажирских вагонах. В тексте максимально сохранены оригинальная пунктуация, лексика и сокращения, принятые в то время

An increase of NAD+ kinase activity in Neurospora cells during adaptation to environmental stress

An increase of NAD+ kinase activity in Neurospora cells during adaptation to environmental stres

Does nitrate reductase play a key role in photoinduction of carotenoid synthesis in Neurospora crassa?

Does nitrate reductase play a key role in photoinduction of caroteniod synthesis in Neurospora crassa

Psychological distress and post-traumatic symptomatology among dental healthcare workers in Russia: Results of a pilot study

The spread of SARS-CoV-2 infection has increased the risk of mental health problems, including post-traumatic stress disorders (PTSD), and healthcare workers (HCWs) are at greater risk than other occupational groups. This observational cross-sectional study aimed to explore the symptoms of depression, anxiety, and PTSD among dental HCWs in Russia during the coronavirus disease 2019 (COVID-19) pandemic. The survey was carried out among 128 dental HCWs from three dental clinics of Ekaterinburg, Russia. The mean age of the sample was 38.6 years. Depression, anxiety, and stress were assessed using the Depression Anxiety and Stress Scale-21 (DASS-21); PTSD was assessed using the PTSD Symptom Scale-Self-Report (PSS-SR); subjective distress was assessed using the Impact of Event Scale-Revised (IES-R). The results indicated that 20.3-24.2% HCWs had mild to extremely severe symptoms of psychological distress, and 7.1-29.7% had clinical symptoms of PTSD. No differences between females and males were revealed. HCWs working directly with patients had significantly higher levels of PTSD symptoms and the risk of PTSD development compared to those working indirectly, whereas older HCWs had significantly higher levels of both psychological distress and PTSD symptoms compared to younger HCWs. Thus, dental HCWs are at high risk for psychological distress and PTSD symptoms during the COVID-19 pandemic. © 2021 by the authors. Licensee MDPI, Basel, Switzerland.The study was partly supported by the Government contract of the Institute of Immunology and Physiology (AAAA-A18-118020690020-1) and the HSE University Basic Research Program (funded by the Russian Academic Excellence Project 5-1000)

Transformation of 6-tetrahydrobiopterin in aqueous solutions under UV-irradiation

© 2017 Elsevier B.V. Melanogenesis disturbance leads to several pathologies, including vitiligo disease. Ultraviolet (UV) narrowband phototherapy (308 or 311nm) is used in treating vitiligo; however, the mechanism of phototherapy is not yet understood. Vitiligo is accompanied by three-fivefold increased de-novo synthesis of (6R)-l-erythro-5,6,7,8-tetrahydrobiopterin (H 4 Bip), its excess and its further oxidation can be considered as significant factors in the pathogenesis of vitiligo. (H 4 Bip), as the phenylalanine 4-hydroxylase coenzyme, catalyzes the oxidation of phenylalanine to tyrosine (a melanin precursor). In this context, photo-transformation of H 4 Bip in aqueous buffer solutions has been studied. HPLC-MS/MS has demonstrated that pterin products of H 4 Bip autoxidation (7,8-dihydropterin (H 2 Ptr), dihydroxanthopterin and pterin) predominate over biopterin products (7,8-dihydrobiopterin (H 2 Bip) and biopterin). We have shown that UV irradiation accelerates the autoxidation while the products of oxidative degradation of H 4 Bip act as photosensitizers. The distinctive feature of photooxidation of H 4 Bip from autoxidation is the formation of dihydropterin (N 2 Ptr) 2 and dihydrobiopterin (N 2 Bip) 2 dimers. By means of HPLC-MS/MS it was found that formation of dihydropterin dimers is the predominant process. The signal of molecular ion of the dimer (N 2 Ptr) 2 (m/z =331) was almost a thousand times higher than the signal of (N 2 Bip) 2 (m/z =479). The key point of the dimerization is photoexcitation (at 310-320nm) of the intermolecular complex (qH 2 Ptr-N 2 Ptr) generated in dark. As a result of the photoreaction azacyclobutane dimers have been formed. In the case of alternation of dark and light intervals H 4 Bip converted into dimers with 96 % yield. The data obtained are discussed in the context of UV-B narrowband vitiligo phototherapy

Parasite Component Community of Smalltooth Sawfish Off Florida: Diversity, Conservation Concerns, and Research Applications

Compared with that of other charismatic elasmobranchs, the component community of metazoan parasites infecting endangered smalltooth sawfish Pristis pectinata is exceedingly poorly characterized: adults of Dermophthirioides pristidis and Neoheterocotyle inpristi (ectoparasitic flatworms of skin and gill, respectively) were the only confirmed parasites prior to the description, based on specimens reported herein, of Mycteronastes caalusi. Our opportune and directed parasitological examinations of 290 smalltooth sawfish (277 live inspections; 13 necropsies; 671 to 2640 mm stretch total length) in south Florida coastal waters revealed at least 8 species of Platyhelminthes, 9 of Arthropoda, 4 of Annelida, and 1 of Nematoda. This collection includes representatives of an undescribed species of Aporocotylidae (Digenea) and myriad new host records, considerably updating and advancing our understanding of smalltooth sawfish symbionts. We also confirm that D. pristidis and N. inpristi are extant and propose D. pristidis as a reliable biological tag. Some of these parasites are evidently highly host-specific and so vulnerable to extinction

ИССЛЕДОВАНИЕ ВЛИЯНИЯ ИНДИВИДУАЛЬНОГО УПРАВЛЕНИЯ ПО ВЫСОКИМ ГАРМОНИКАМ НА ВИБРОПЕРЕГРУЗКИ, ВЫЗВАННЫЕ СИЛОЙ ТЯГИ НЕСУЩЕГО ВИНТА ВЕРТОЛЕТА

The paper presents numerical results analysis of main rotor vibration due to helicopter main rotor thrust pulsation.The calculation method, the object of research and numerical research results with the aim to reduce the amplitude of the vibrations transmitted to the hub from the helicopters main rotor by the individual blade control in azimuth by the installation angle of blades cyclic changes are set out in the article. The individual blades control law for a five-blade main rotor based on the blade frequencies is made. It allows reducing the vibration from thrust. Research takes into account the main rotor including and excluding the blade flapping motion. The minimal vibrations regime is identified.Numerical study of variable loads caused by unsteady flow around the main rotor blades at high relative speeds of flight, which transmitted to the rotor hub, is made. The scheme of a thin lifting surface and the rotor vortex theory are used for simulation of the aerodynamic loads on blades. Non - uniform loads caused by the thrust, decomposed on the blade harmonic and its overtones. The largest values of deviation from the mean amplitude thrust are received. The analysis of variable loads with a traditional control system is made. Algorithms of higher harmonics individual blade control capable of reducing the thrust pulsation under the average value of thrust are developed.Numerical research shows that individual blade control of high harmonics reduces variable loads. The necessary change in the blade installation is about ± 0,2 degree that corresponds to the maximum displacement of the additional con- trol stick is about 1 mm.To receive the overall picture is necessary to consider all six components of forces and moments. Control law with own constants will obtained for each of them. It is supposed, that each of six individual blade control laws have an impact on other components. Thus, the problem reduces to the optimization issue. The individual blade control general law will be received as a result. It will meet a lot of conflicting requirements.Статья посвящена анализу результатов расчетного исследования виброперегрузки несущего винта, вызванной пульсацией силы тяги несущего винта вертолета.В статье представлены методика расчета, объект исследования и результаты численного исследования индивидуального управления каждой лопастью по азимуту путем циклического изменения угла их установки с целью уменьшения амплитуды вибраций, передаваемых на втулку несущим винтом вертолета. Выработан закон индиви-дуального управления лопастями по лопастным частотам для пятилопастного несущего винта, позволяющийуменьшить вибрации силы тяги с учетом и без учета махового движения лопасти. Определена область, где виброперегрузки будут минимальные.Проведены численные исследования переменных нагрузок, обусловленных нестационарным обтеканием лопастей несущего винта, передаваемых на втулку винта при больших относительных скоростях полета. Для моделирования процесса обтекания лопастей использовалась схема тонкой несущей поверхности в вихревой теориинесущего винта. Неравномерные нагрузки, вызванные силой тяги, разложены по лопастной гармонике и оберто-нам. Выделены наибольшие величины отклонения от средней амплитуды силы тяги. Выполнен анализ переменных нагрузок с традиционной системой управления. Выработаны алгоритмы управления высшими гармониками, которые реализуются при управлении лопастями и позволяют уменьшить пульсации силы тяги при фиксированном среднем значении силы тяги.Расчетные исследования показали, что индивидуальное управление высокими гармониками лопасти снижает уровень переменных нагрузок, при этом необходимое изменение установки лопасти составляет ±0,2 градуса, что соответствует максимальному дополнительному перемещению рычага управления около 1 мм.Для получения общей картины необходимо учитывать все шесть компонент сил и моментов. Для каждого из них будет выработан свой закон управления и свои коэффициенты. Предполагается, что каждый из шести законов управления по отдельности будет влиять на другие компоненты. Таким образом, задача сводится к оптимиза-ционной задаче, в результате которой получится общий закон индивидуального управления лопастями, удовлетво-ряющий многим противоречивым требованиям

ОСОБЕННОСТИ МОДЕЛИРОВАНИЯ ОБТЕКАНИЯ НЕСУЩЕГО ВИНТА ВЕРТОЛЕТА С УЧЕТОМ ПРОИЗВОЛЬНОГО ДВИЖЕНИЯ ЛОПАСТЕЙ

The article considers the problem of the flow around the helicopter main rotor taking into account blades flapping in the plane of rotation and in the plane of thrust as well as the elastic blades deformation. The rotor rotation is modeled by the method of converting Navier-Stokes equations from a fixed coordinate system associated with the incoming flow into a rotating system associated with the rotor hub. For axial flow problems, this makes it possible to formulate the problem as stationary at a constant rotational speed of rotor. For a mode of skewed flow around the rotor in the terms of incident flow in this system it is necessary to solve the non-stationary problem. To solve the problem, the method of deformable grids is used, in which the equations are copied taking into account the grid nodes motion determined in accordance with the spatial blades motion, and SST turbulence model is used for closure. The results of the test calculations of the main rotor aerodynamic characteristics with and without blade flapping are presented in this paper. The coefficients of the main rotor thrust cT and the blades hinge moments mh are compared. The calculations were carried out in the CFD software ANSYS CFX (TsAGI License No. 501024). The flow around a four-bladed main rotor of a radius of 2.5 meters is modeled in the regime of skewed flow. The speed of the incoming flow came to 85 m/s under normal atmospheric conditions. The rotor was at an angle of attack of −10˚. To calculate the rotor motion without taking into account the flapping movements, we used the nonstationary system of Navier-Stokes equations with the closure with SST turbulence model. The calculation was being carried out until the change in the maximum value of the rotor thrust during one revolution became less than 1%. For modeling flapping blade movements, the control laws and equations describing the angle of blade flapping as a function from its azimuth angle obtained from the experiment were used. The procedure for reconstructing the grid according to a given law was conducted using standard grid deformation methods presented in the ANSYS CFX software. When solving the nonstationary Navier-Stokes equations, a dual time step was used. The obtained results show that accounting of the effect of flapping movements and cyclic control of the blades has an impact on the character of changing the main rotor thrust coefficient during one revolution and significantly changes the shape of the graph of the hinge moment coefficient of each blade.Рассматривается задача обтекания несущего винта (НВ) вертолета с учетом махового движения лопастей в плоскости вращения и в плоскости тяги, а также упругой деформации лопастей. Вращение винта моделируется методом преобразования решаемых уравнений из неподвижной системы координат, связанной с набегающим потоком, во вращающуюся систему, связанную с втулкой винта. Для задач осевого обтекания это делает возможным формулировать задачу как стационарную при постоянной скорости вращения винта. Для режима косого обтекания винта в условиях набегающего потока в этой системе необходимо решать нестационарную задачу. Для решения задачи использован метод деформируемых сеток, в котором уравнения записываются уже с учетом движения узлов сетки, определяемых в соответствии с пространственным движением лопастей, а для замыкания используется SST модель турбулентности. В данной работе представлены результаты тестовых расчетов аэродинамических характеристик НВ без и с учетом махового движения лопастей. Проводится сравнение коэффициентов силы тяги НВ CT и шарнирных моментов лопастей mш. Расчеты проводились в CFD пакете программ ANSYS CFX (Лицензия ЦАГИ № 501024). Смоделировано обтекание четырехлопастного НВ радиусом 2,5 метра на режиме косого обтекания. Скорость набегающего потока составляла 85 м/с при нормальных атмосферных условиях. Винт находился под углом атаки −10˚. Для расчета движения винта без учета маховых движений использовалась нестационарная система уравнений Навье – Стокса с замыканием SST моделью турбулентности. Расчет проводился до тех пор, пока изменение максимального значения тяги винта за оборот не станет менее 1 %. Для моделирования маховых движений лопасти были взяты законы управления и уравнения, описывающие угол взмаха лопасти как функцию от ее азимутального угла, полученные из эксперимента. Процедура перестроения сетки по заданному закону осуществлялась с использованием стандартных методов деформации сетки, представленных в программе ANSYS CFX. При решении нестационарных уравнений Навье – Стокса был использован дуальный шаг по времени. Полученные результаты показывают, что учет влияния маховых движений и циклического управления лопастями влияет на характер изменения коэффициента тяги НВ  за один оборот и существенно влияет на вид графика коэффициента шарнирного момента каждой лопасти

Seroprevalence of sars-cov-2 antibodies in symptomatic individuals is higher than in persons who are at increased risk exposure: The results of the single-center, prospective, cross-sectional study

The present study aimed to assess antibody seropositivity prevalence among symptomatic individuals and individuals with a high risk of occupational exposure to SARS-CoV-2. Participants from Chelyabinsk (Russian Federation) who were at an increased risk of exposure to SARS-CoV-2 (high-risk group, n = 1091) and participants who either had symptoms consistent with COVID-19 or were suspected to have experienced COVID-19 in the past (symptomatic group, n = 692) were enrolled between 28 September and 30 December 2020. Blood samples were tested by enzyme-linked immunosorbent assay D-5501 SARS-Cov-2-IgG-EIA-BEST and D-5502 SARS-Cov-2-IgM-EIA-BEST (AO Vector-Best, Novosibirsk, Russia). The overall seropositivity rate was 28.33–28.53%. SARS-CoV-2 antibodies were detected in 17.23% (adjusted prevalence of 17.17–17.29%) of participants in the high-risk and 45.95% (adjusted prevalence of 45.91–46.24%) in the symptomatic group. Higher IgG and IgM titers were observed in women compared to men, as well as in participants in the symptomatic group compared to those in the high-risk group. The results indicate that the seroprevalence among residents in several Russian regions is low (28.38%) and inadequate to provide herd immunity. The lower seroprevalence among participants in the high-risk group may be attributed to the enforcement of healthcare protocols and the use of adequate personal protective equipment. © 2021 by the authors. Licensee MDPI, Basel, Switzerland.The reported study was funded by RFBR and NSFC (project No.20-515-55003), by the NSFC (project No. 82161138003), and partly by the Government contract of the Institute of Immunology and Physiology (AAAA-A21-121012090090-9)