Main factors affecting the structure and properties of titanium and cobalt alloys manufactured by the 3D printing

This paper is short review the main factors affecting the structure and properties of the metals manufactured by additive technology (selective laser melting). A comparative analysis of the structure and properties of Ti6Al4V or CoCrMo alloys obtained by selective laser melting is presented. We describe the capabilities of laser melting method for producing materials with high density and high mechanical properties. The optimized process parameters for 3D printed medicine materials Ti6Al4V and CoCrMo with high density of are discussed. © Published under licence by IOP Publishing Ltd.This work was supported by Russian Found of Basic Research N “Diagnostics” AAAA-A18-118020690196-3

Structure of 3D Printed Ti-6Al-4V Alloy after Low-frequency Processing

The structure and residual elastic stresses in 3D printed (Selective laser melting) Ti-6A1-4V samples after the low-frequency vibration processing were investigated. The studied samples were manufactured horizontally in respect to the building platform. Different vibration oscillations modes (vertical, horizontal, and elliptical) were chosen for study. The oscillations were done with frequency of 16 Hz, and a processing time was 20 minutes. Studies shown that 3D printed samples had a high level of residual elastic stresses, which were changed after vibration treatment. The influence of the low-frequency processing on the phase composition of the alloy was found. © Published under licence by IOP Publishing Ltd

Laser induced magnetization switching in films with perpendicular anisotropy: a comparison between measurements and a multi-macrospin model

Thermally-assisted ultra-fast magnetization reversal in a DC magnetic field for magnetic multilayer thin films with perpendicular anisotropy has been investigated in the time domain using femtosecond laser heating. The experiment is set-up as an optically pumped stroboscopic Time Resolved Magneto-Optical Kerr Effect magnetometer. It is observed that a modest laser fluence of about 0.3 mJ/square-cm induces switching of the magnetization in an applied field much less than the DC coercivity (0.8 T) on the sub-nanosecond time-scale. This switching was thermally-assisted by the energy from the femtosecond pump-pulse. The experimental results are compared with a model based on the Landau Lifschitz Bloch equation. The comparison supports a description of the reversal process as an ultra-fast demagnetization and partial recovery followed by slower thermally activated switching due to the spin system remaining at an elevated temperature after the heating pulse.Comment: 8 pages, 10 figures, to be submitted to PR

Role Of Retroelements In The Development Of COVID-19 Neurological Consequences

Retroelements play a key role in brain functioning in humans and other animals, since they represent dynamic regulatory elements controlling the expression of specific neuron types. The activity of retroelements in the brain is impaired under the influence of SARS-CoV-2, penetrating the blood-brain barrier. We propose a new concept, according to which the neurological complications of COVID-19 and their long-term effects are caused by modified expression of retroelements in neurons due to viral effect. This effect is implemented in several ways: a direct effect of the virus on the promoter regions of retroelement-encoding genes, virus interaction with miRNAs causing silencing of transposons, and an effect of the viral RNA on the products of retroelement transcription. Aging-related physiological activation of retroelements in the elderly is responsible for more severe course of COVID-19. The associations of multiple sclerosis, Parkinson’s disease, Guillain-Barré syndrome, acute disseminated encephalomyelitis with coronavirus lesions also indicate the role of retroelements in such complications, because retroelements are involved in the mechanisms of the development of these diseases. According to meta-analyses, COVID-19-caused neurological complications ranged 36.4-73%. The neuropsychiatric consequences of COVID-19 are observed in patients over a long period after recovery, and their prevalence may exceed those during the acute phase of the disease. Even 12 months after recovery, unmotivated fatigue, headache, mental disorders, and neurocognitive impairment were observed in 82%, 60%, 26.2-45%, and 16.2-46.8% of patients, correspondingly. These manifestations are explained by the role of retroelements in the integration of SARS-CoV-2 into the human genome using their reverse transcriptase and endonuclease, which results in a long-term viral persistence. The research on the role of specific retroelements in these changes can become the basis for developing targeted therapy for neurological consequences of COVID-19 using miRNAs, since epigenetic changes in the functioning of the genome in neurons, affected by transposons, are reversible

Electromagnetically induced switching of ferroelectric thin films

We analyze the interaction of an electromagnetic spike (one cycle) with a thin layer of ferroelectric medium with two equilibrium states. The model is the set of Maxwell equations coupled to the undamped Landau-Khalatnikov equation, where we do not assume slowly varying envelopes. From linear scattering theory, we show that low amplitude pulses can be completely reflected by the medium. Large amplitude pulses can switch the ferroelectric. Using numerical simulations and analysis, we study this switching for long and short pulses, estimate the switching times and provide useful information for experiments

Standardization in the field of powder metallurgy

Standardization always contributes to technical development. Insufficient standards in all areas of activity and slower updating of existing ones make it difficult to respond to innovations, to speed up their access to domestic and global marketsСтандартизация всегда способствует техническому развитию. Недостаточное число стандартов в любых сферах деятельности и замедленное обновление существующих затрудняет реагирование на инновации, ускорение их доступа на внутренние и глобальные рынк

Assessment of the reliability of the locomotive based on statistical methods of quality management

The lack of reliability of the diesel locomotive operation leads to a decrease in the technical and economic efficiency of using the locomotive service of the enterprise. During the experiment which aimed at assessing the reliability of repair and maintenance of a diesel locomotive in one of the railway divisions of OJSC "Russian Railways", it was found that the failures may be distributed by types of equipment, based on the failures for 12 months of 2017. Statistical quality management methods were used to identify the most problematic types of locomotive equipment and specific causes of failures. © Published under licence by IOP Publishing Ltd

Improving the reliability of locomotives by implementation of the operation of RAMS means and methods

В статье рассмотрена возможность управления надежностью локомотивов путем внедрения комплексной системы RAMS. Применение одного из инструментов FRACAS, используемого в системе RAMS позволяет создать базу знаний, которая обеспечит формирование полной, объективной структурированной информации о неисправностях, отказах и событиях, связанных с возникновением отказов.The article considers the possibility of controlling the reliability of locomotives by introducing an integrated system RAMS. The use of one of the FRACAS means used in the RAMS system allows you to create a knowledge base that will ensure the formation of complete, objective, structured information about faults, failures and events associated with the occurrence of failures

Structure and Productivity of \u3ci\u3eHaloxylon ammodendron\u3c/i\u3e Communities in the Mongolian Gobi

Communities of Haloxylon ammodendron are widespread in the Mongolian Gobi where they play a significant role in biodiversity preservation. They occupy several main types of habitats, showing differences in density, projective cover, and productivity. Haloxylon ammodendron plays a similar, if not even more important role in the arid zone of Mongolia as the principal forest-making trees in the Northern part of the country. The complex set of quantitative parameters of Haloxylon ammodendron stands studied here in respect to temporal dynamics can serve as an indicator of both the vitality of desert ecosystems, and of environmental change