Журнал включен в Перечень вак рФУчРеЖдеН ООО «Издательство «Наука сегодня» Журнал зарегистрирован Федеральной службой по надзору в

The tire tread (inflated) may have a convex (toroidal) shape. At present, there is practically no data on the influence of this structural parameter of the tire on its power and kinematic characteristics when rolling with a slip. The solution to this problem, given in this paper, is based on the consideration of contact phenomena in the friction pair “elastic wheel – rigid support surface”. As a result, relationships that make it possible to determine the lateral force, the turning moment acting in the contact area, the friction loss in the contact area for wheels with different toroidalities as a function of the slip angle and the longitudinal tangential force realized in the contact area are obtained; conclusions about the influence of the convexity on the lateral force, the stabilizing moment and the power of friction losses in the contact area are drawn.

Car tire tests, including rolling resistance tests, are often performed on drum stands. Car tests on drum stands of various designs are also becoming more widespread: with a different number of drums, their locations and types of drives. However, in the literature there are no works describing the process of interaction of the wheel with the drum. In this regard, there is a need to consider the mechanics of the interaction of an elastic wheel with a drum and determine its kinematic and power characteristics, which is the task of this study. The mechanics of rolling the wheel against the drum is considered, taking into account the frictional interaction of the pair “elastic wheel – rigid drum” using the theory of preliminary displacement of the wheel elements in the zone of contact with the drum. This made it possible, inter alia, to obtain relationships for determining the rolling resistance caused by hysteresis losses in the wheel material, the tangential force acting in the contact, the moment on the wheel, the power of friction losses in the contact, the coordinates of the boundary of the adhesion and sliding sections in the contact of the wheel with the drum, relative loss of speed (slippage) of the wheel. The interaction of the wheel with two drums is also considered.

Wheel tire wear annually takes hundreds of thousands of rubber tons. In this regard, the issue of reducing this negative phenomenon is urgent, for which it is necessary to know what and how affects tire wear. Factors affecting the wear of elastic wheels can be different: recipe of the rubber compound, the amount of traction (or braking) force in contact with the road, the type of movement is straight or cornering, the installation angles of the wheels (camber and toe-in angles), tire design, driving mode - uniform or with acceleration (braking). In this paper, we consider the influence on tire wear of such parameters as the value of the longitudinal force acting in the contact, the camber and toe-in angles, the radius of the motion trajectory and such a structural parameter as the convexity of the tread. When assessing the wear intensity, as is accepted by most researchers, we proceed from the fact that wear is proportional to the friction power in the contact of two interacting bodies.

In this study, the team of authors solves the problem of increasing the energy efficiency of power plants by reducing losses while lowering the coefficient of friction. This problem is solved with the help of a multifunctional additive to lubricating oils, which are a surface-active substance (surfactant) capable of changing the friction conditions of contacting surfaces in a small amount when introduced into tribological units. The tests were carried out on a friction machine II5018 on a block-roller friction pair (the material of the roller is gray cast iron SCh20, the material of the block is steel 65). During the study, the moment and coefficient of friction were determined. A friction coefficient decrease of up to 50 % was obtained, which proves the effectiveness of the proposed compositions.

A comprehensive study of the effectiveness of two-layer coatings based on PEG and silver nitrate to combat pathogenic microorganisms – the agents of implant-associated infections – was conducted. The paper deals with the features of the structural transformations that occur in the polymer matrix at the stage of deposition and formation of the thin layer, as well as when the thin layer is heat-treated. The PEG matrix was shown to promote thermal stabilization of silver nitrate, which is manifested in the presence of significant amount of oxide (AgO and Ag2O) and undecomposed salt, in addition to silver nanoparticles, in the annealed organic layer.

The composite materials based on polymer and oligomer blends with different thermodynamic compatibility have been developed. It is shown that for polymer and oligomer blends of products formed as result of the thermogasdynamic synthesis of fluorine-containing compounds, the ability of oligomeric matrix to multiply deformation and alternating transfer is the most important. In polymer-polymer systems formed in a melt by various technologies the most important factor is the structure of the boundary layers determining the parameters of the stress-strain and tribological characteristics of the composites. The effect of physical compatibilization during the introduction of nanoscale metal-containing and carbon-containing particles into the blend compositions has been established. This effect promotes the thermodynamic compatibility and resistance to the action of thermal-oxidative medium on composites.

This paper describes directions of realization of the multilevel modification principle in materials science and technology of polymer composite materials based on thermoplastics. It is shown that the introduction of nanoscale particles of different structures and production technologies into the composition of the composite makes it possible to transform the structure at various organization levels, which leads to the achievement of a synergistic effect of increasing the parameters of deformation-strength, tribotechnical characteristics and resistance to the action of thermal-oxidative medium. One of the perspective technologies of the nanomodifiers introduction into the composite material is the diffusion treatment of components and products in precursor solutions. Mixture of composite materials with increased parameters of performance characteristics for use in engineering, chemical and mineral resource industries have been developed.

ФГБУ «Эндокринологический научный центр» Минздрава России, Москва (директор – академик РАН И.И. Дедов) Петрова Д.В.*, Дзеранова Л.К., Григорьев А.Ю., Иващенко О.В., Лапшина А.М., Воронцов А.В. Болезнь Иценко-Кушинга (БИК) – это многосимптомное прогрессирующее нейроэндокринное заболевание, обусловленное опухолью гипофиза, продуцирующей избыточное количество АКТГ. В большинстве случаев (80–85%) причиной развития болезни является кортикотрофная микроаденома гипофиза (располагающаяся внутри турецкого седла, размерами 3–10 мм, реже определяются множественные микроаденомы) и только в 15% случаев встречается гиперплазия кортикотрофов или макроаденома гипофиза, распространяющаяся за пределы турецкого седла [1–2]. При этом макроаденомы при БИК чаще распространяются супраселлярно (до 10%), инфраселлярный рост опухоли встречается сравнительно редко (до 5%). При стертой клинической картине на первое место могут выступать симптомы, обусловленные развитием «масс-эффекта» опухоли при ее распространении на окружающие гипофиз структуры. Супраселлярный рост приводит к компрессии хиазмы зрительных нервов, что проявляется ограничением полей зрения, инфраселлярный рост – к разрушению дна турецкого седла и развитию назальной ликвореи. Назальная ликворея (НЛ) – истечение цереброспинальной жидкости (ЦСЖ) из субарахноидального пространства головного мозга в полость носа вследствие дефектов в костях основания черепа и твердой мозговой оболочке (ТМО). Опасность ликвореи заключается в том, что в результате разгерметизации полости черепа и возникновения сообщения с окружающей средой, возможно проникновение патогенных микроорганизмов в полость черепа с развитием таких угрожающих жизни больного состояний, как менингит, менингоэнцефалит, вентрикулит. Среди угрожающих жизни осложнений при БИК лидируют инфекционные и сердечно-сосудистые, обусловленные длительным течением самого гиперкортицизма. Но в случае развития НЛ при экспансии опухоли в сфеноидальный синус с разрушением дна турецкого седла возникает непосредственная угроза жизни пациента. В данной статье представлен пример больной с морбидным ожирением и отсутствием специфических клинических проявлений гиперкортицизма, у которой диагноз БИК был поставлен по результатам лабораторно-инструментального обследования, проведенного по поводу развития спонтанной НЛ. В связи с представленным клиническим случаем оговорены необходимые методы первоначального скрининга для своевременного выявления гиперкортицизма и обращено пристальное внимание на возможность развития такого угрожающего жизни осложнения как НЛ у пациентов с БИК при легком течении самого гиперкортицизма. Ключевые слова: назальная ликворея, ожирение, макроаденома, гиперкортицизм, адренокортикотропный гормон, болезнь ИценкоКушинга.

A systematic analysis of factors that influence on the processes of protective coating formation based on mixed matrices has been presented in the paper. The paper demonstrates a significant role of energy parameters of modifier drop-phase dispersed particles formed in the process of pneumatic spraying and surface layer of a metal substrate on the mechanisms pertaining to formation of coating structure with optimal characteristics. Compositions of anticorrosive and tribological coatings for application in the designs of higher resource automotive components have been proposed in the paper.