Hall carrier density and magnetoresistance measurements in thin film vanadium dioxide across the metal-insulator transition

Temperature dependent magneto-transport measurements in magnetic fields of up to 12 Tesla were performed on thin film vanadium dioxide (VO2) across the metal-insulator transition (MIT). The Hall carrier density increases by 4 orders of magnitude at the MIT and accounts almost entirely for the resistance change. The Hall mobility varies little across the MIT and remains low, ~0.1cm2/V sec. Electrons are found to be the major carriers on both sides of the MIT. Small positive magnetoresistance in the semiconducting phase is measured

Three-terminal field effect devices utilizing thin film vanadium oxide as the channel layer

Electrostatic control of the metal-insulator transition (MIT) in an oxide semiconductor could potentially impact the emerging field of oxide electronics. Vanadium dioxide (VO2) is of particular interest due to the fact that the MIT happens in the vicinity of room temperature and it is considered to exhibit the Mott transition. We present a detailed account of our experimental investigation into three-terminal field effect transistor-like devices using thin film VO2 as the channel layer. The gate is separated from the channel through an insulating gate oxide layer, enabling true probing of the field effect with minimal or no interference from large leakage currents flowing directly from the electrode. The influence of the fabrication of multiple components of the device, including the gate oxide deposition, on the VO2 film characteristics is discussed. Further, we discuss the effect of the gate voltage on the device response, point out some of the unusual characteristics including temporal dependence. A reversible unipolar modulation of the channel resistance upon the gate voltage is demonstrated for the first time in optimally engineered devices. The results presented in this work are of relevance toward interpreting gate voltage response in such oxides as well as addressing challenges in advancing gate stack processing for oxide semiconductors

Specialized railway carriage for grain

This article deals with the worked out specialized railway carriage for grain for the transportation process throughout the Republic of Uzbekistan railway network, with the unconditional provision of train traffic safety, which is one of the most important components of the rolling stock of railway transport. The features of the load-bearing structure of the railway carriage for grain are that it is made based on a four-axle platform and a universal container. Evaluation of the strength of the metal structure of the grain car was carried out following the requirements of the “Standards for the calculation and design of new and modernized cars of the railways of the Ministry of Railways with a gauge of 1520 mm (non-self-propelled)”. Based on theoretical studies, it was justified that the design of a railway carriage for grain with a capacity of 83.6 m3 and a carrying capacity of 65 tons. For the first test of a railway carriage for grain, the number 43925684 was assigned. The proposed new grain carriage will reduce operating costs and reduce rolling stock downtime during reloading operations. It will create the possibility of fulfilling contractual agreements drawn up for small volumes of traffic within the country

TO THE CALCULATION OF SOLID-STATE CARGO ATTACHMENT UNDER THE INFLUENCE OF LONGITUDINAL FORCES

The article is devoted to the calculation of cargo fastening using the current method. It is proved that according to the existing method, the force in all elastic cargo mounts of both one and the other direction under the influence of longitudinal forces has the same value, regardless of the different location of the geometric parameters of the mounts in space. Calculations of forces in elastic elements of fastening by the specified method are given. The results of the comparative analysis showed that the forces in all wire fasteners, in contrast to the existing method of calculation, have different values. The main drawback of the updated calculation method is noted: the strength of individual elements of fasteners is not provided – the forces in them are more than twice the permissible values

Old age as a basic concept of social gerontology: Linguistic-theoretical aspect

This article examines the views of modern scientists on the phenomenon of old age, as well as the range of problems and concepts of special social science –gerontology, designed to solve demographic, socio-economic problems of aging. It is noted that social gerontology, which is a branch of the abovementioned science, also relates to the group of sciences of the linguistic cycle: culture of speech, stylistics, sociolinguistics and others. It is pointed out that the speeches of elderly people are characterised by specific lexical units and idiomatic expressions. Issues related to the old age and the ageing of man since ancient times have been in the focus of philosophers' attention. The article mentions the works of the famous statesman of the Roman Empire, politician, philosopher and orator Mark Tullius Cicero (106-43). The author concludes that the integration of social gerontology with linguistic science may lead to the emergence of a new scientific field, that will possibly be named linguistic gerontology or gerontological linguistics

Does the degree of preoperative mitral regurgitation predict survival or the need for mitral valve repair or replacement in patients with anomalous origin of the left coronary artery from the pulmonary artery?

BackgroundAnomalous origin of the left coronary artery from the pulmonary artery causes severe myocardial ischemia, global left ventricular dysfunction, and annular dilatation producing varying degrees of mitral regurgitation. Mitral regurgitation secondary to the left ventricular or papillary muscle dysfunction in infants will usually improve in the absence of ongoing ischemia. The aim of this study is to determine the influence of the degree of preoperative mitral regurgitation on the early and late outcomes of patients with anomalous origin of the left coronary artery from the pulmonary artery who underwent coronary reimplantation.MethodsTwenty-five patients underwent coronary reimplantation and 1 early patient had ligation during a 30-year period (median age, 4 months; range, 1 month to 16 years), with a median follow-up of 7 years (range, 4 months to 25 years). Before repair, 7 infants (27%) presented in extremis requiring ventilatory and inotropic support, and 17 patients (65%) presented with heart failure. Mitral regurgitation was present in all patients: trivial in 6 patients, mild in 12 patients, moderate in 5 patients, and severe in 3 patients. No patient underwent mitral valve repair or replacement at the time of anomalous origin of the left coronary artery from the pulmonary artery repair.ResultsHospital survival was 92%. Three patients underwent mitral valve repair or replacement at the mean time of 3.5 years (all with severe preoperative mitral regurgitation). The degree of mitral regurgitation gradually improved in all remaining patients with preoperative mild and moderate mitral regurgitation. Echocardiographic studies demonstrated improvement in left ventricular function in all children. None of the patients showed any evidence of supravalvar pulmonary stenosis as a result of their pulmonary artery reconstruction.ConclusionLong-term clinical outcome and left ventricular function are good despite severe left ventricular dysfunction at presentation. Mitral valve repair or replacement is generally not necessary at the time of anomalous origin of the left coronary artery from the pulmonary artery repair. Significant residual mitral regurgitation is present in some patients and can usually be managed surgically at a later date depending on its degree of severity

Simulation of the process of cotton drying under the influence of a heat agent in a spiked - screw cleaner

The spiked-screw cleaner was divided into several sections, and taking into account the same amount of cotton in all sections at the same time, the drying process of cotton in each section was studied from a theoretical point of view. A drying agent was supplied from the upper side of each section, and the process of heat exchange with the cotton rotating and advancing in the spiked-screw was studied. In this case, equations were obtained that indicate that the level of small impurities released from cotton depends on the temperature of the cotton when hitting the heated cotton with piles in each section of the cleaner, moving it on the mesh surface and throwing the cotton up. It was found that the change of the temperature of the cotton fiber depending on the number of sections n and the air temperature in the open part of the surface T1 (K) depending on the screw angle θ is close to the law of change of the cotton fiber on a straight line. It was found that the process of moisture exchange in its components depends on the effect of hot air and the drying mode when extracting moisture from cotton moving in a pile-screw cleaner

Strength assessment of the body of a weight checking wagon type 640-VPV

In the article, necessary to design and build new and modern weighing wagons to replace the outdated ones, but this will take some time. Thus, before the construction of new wagons and the optimal use of existing wagons, it is necessary to extend their service life. Extension of the service life of weighing wagons involves determining the current technical condition and residual resources of these wagons. For this purpose, a survey and analysis of the main bearing elements and structural parameters of the bodies of the weighing wagons were carried out