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The mechanical reliability of metallic components is vital for the stable operation of electrical equipment, especially for those used in ultra-high voltage transmission and electromagnetic launching, where metallic materials inevitably suffer from high-density current and strong magnetic field. However, little has been known about the mechanical behavior of metals under the electric-magnetic coupling stimuli. Here, by performing quantitative electromechanical tests under the built-in magnetic field inside transmission electron microscope, we found that copper, one of most commonly used conductive metals, can be significantly softened by the coupled electrical-magnetic stimuli, manifested as notable yield strength drop by five-times and obvious creep deformation at room temperature. A plausible mechanism behind the unusual softening, local-Lorentz-force-assisted dislocations depinning, has been proposed. Our results shed new light on understanding the deformation-induced failure of metals served in electromagnetic environments, and also inspire a new mechanical processing way for reshaping metals at much lower loads and temperatures. [Display omitted] [ABSTRACT FROM AUTHOR]

Obesity has caused a huge burden of disease. Few studies have explored individuals' environmental exposure level and the impact of multiple environmental exposures on obesity. The aim of this study was to explore individual air pollution exposure evaluation, and the association between and multiple environmental factors and obesity among adult residents in rural areas of China. In this study, 8400 residents of 14 districts and counties in eastern of China were selected by multistage stratified cluster sampling, and a total of 8377 residents were included in the final analysis. We adopted BMI (Body Mass Index) > 28 kg/m2 as the definition of obesity. First, an individual air pollution evaluation model was established based on the monitoring data of air pollution stations closest to residential address, different demographic characteristics of residents and daily living habits using generalized linear model and random forest model. Then, we used Bayesian Kernel Machine Regression (BKMR) and Quantile g-Computation (QgC) models to explore multiple environmental exposures on obesity. The results showed that six air pollutants were significantly positively associated with obesity, and green space had a significant protective effect on obesity. The BKMR model showed that the effects of different air pollutants on obesity were significantly enhanced by each other, while green space significantly reduced the positive effect of air pollution on obesity. The QgC model showed a significant positive association with obesity when all environmental factors were exposed as a whole, especially in males, higher household incomes and young people. It suggested that relevant authorities should improve regional air quality and green space to reduce the burden of disease caused by obesity. [Display omitted] • We evaluated individual air pollution exposure of residents in Anhui Province. • There was a positive association between air pollution and obesity. • Green space was negatively associated with obesity. • Green space could attenuate effect of air pollution on obesity. • Multiple environmental exposure was positively associated with obesity. [ABSTRACT FROM AUTHOR]

Filling body is an important structure to support the safety of coal mine goaf. The cemented gangue backfill (CGB) is a multiphase heterogeneous brittle material composed of coal gangue, hydration reactants, pores and microcracks. According to Micromechanics studies, the accumulation and development of meso-structural damage in heterogeneous brittle materials is the direct cause of macroscopic failure. In this paper, particle flow numerical software PFC2D is used to simulate the meso-structure evolution of CGB. Considering the particle size of filling material, the coal gangue particles are drawn according to the real shape by vector software, then import it into PFC2D by FISH language and constructed as Clump unit. The relationship between micro-characteristics such as particle force chain distribution, cracks and pores and mechanical properties of CGB is analyzed. The results show that the stress-strain and crushing mode of the numerical simulation model have a good correspondence with the laboratory test results. The internal force chain distribution and fracture-pore evolution law of the model particles are analyzed. It is found that most of the force chains are concentrated near the larger particle units, forming the 'skeleton force chain' phenomenon. The initial cracks are mainly produced around the coal gangue particle unit. With the increase of axial pressure, the cracks grow obliquely from 30° to 45°, and finally macroscopic cracks are generated. Due to the hydration product generated, the internal porosity is gradual decrease. Other than that, during the uniaxial compression process，the porosity of the same curing age decreases first and then increases, and the pores are sudden increase after the complete crushing stage. • The coal gangue particles are drawn according to the real shape by vector software, and then imported them into PFC2D by FISH language as the Clump unit. • Based on the experimental data and image analysis, a PFC discrete element numerical analysis model was established. The meso-damage evolution law and failure model of CGB particles were discussed. • A mechanical model that can be extended from meso-analysis to macro-performance is constructed to reveal the internal mechanism of the macro-performance of multiphase heterogeneous materials. [ABSTRACT FROM AUTHOR]

A novel rotating conductive joint that comprises an inner raceway, outer raceway, and a roll ring is proposed in this study. The tribological and conductive properties of the rolling rings were studied under current conditions of 0–20 A. The current density of the rolling contact reached 419 A/mm2 when transmitted at 20 A. However, a high current could result in a high-friction coefficient and severe wear. The results of optical microscopy and electron back-scattered diffraction showed that the grain boundary was partially annihilated, and the stress decreased in the wear area under 10 and 20 A. On the wear surface, the current-carrying friction caused the hardening, and the electroplasticity caused softening. The surface hardness of the wear area was the result of competition between hardening and softening, which reached its highest value at 5 A. • A single roll ring could transmit a current of 20 A. • The annihilation of the boundaries was observed when the current density exceeded 409 A/mm2. • Hardening and softening competed on wear surface. [ABSTRACT FROM AUTHOR]

Herein, in situ MoB particles reinforced Cu-Al matrix composites are prepared by sintering the Cu and MoAlB mixture. During the sintering process, Al atoms can diffuse out of the layered MoAlB and solid-dissolve into the Cu matrix, resulting in the formation of laminate MoB and Cu-Al alloy. The mechanical properties of as-prepared composites are significantly improved because of multiple strengthening mechanisms. Moreover, the two-body abrasive and adhesive wear effects are inhibited on account of the pinning effect of MoB particles. With the MoAlB content increasing up to 20 wt% and 30 wt%, a layer of tribo-film can be generated due to the tribo-oxidation reaction during the sliding, which can provide lubrication to reduce friction and wear. • In-situ MoB reinforced Cu-Al matrix composites are prepared for the first time. • The mechanical and tribological properties of as-prepared composites are improved. • Two-body abrasion and adhesive wear can be inhibited with MoAlB addition. • The generating tribo-film leads to the low friction coefficient and wear rate. [ABSTRACT FROM AUTHOR]

• Analyzed the drawbacks of binary classification algorithms in multi-classification problems. • A comprehensive evaluation index for fault features is proposed. • An improved machine learning method for rotor fault diagnosis. To ensure the long-term safe and reliable operation of mechanical equipment, it is necessary to carry out fault diagnosis of key components in the mechanical system. A rotor fault diagnosis method based on non-fuzzy solution weighted BP-AdaBoost (NFSW-BP-AdaBoost) is proposed in this paper. First, the rotor vibration signal is transformed into a high-dimensional feature set. Then, the VC value is used to obtain the high-dimensional feature sequence. Finally, the NFSW-BP-AdaBoost method is used to diagnose the type and degree of rotor fault. The core of this article is to analyze the fuzzy solution of the combined binary classifier applied to multi-classification problems in decision-making, and put forward the non-fuzzy solution coefficient to weigh the conclusion of the combined multi-classifier, highlighting the sensitivity to the non-fuzzy solutions of each multi-classifier. The experimental analysis results show that the recognition rate of the classification method for fault types can reach more than 97%. [ABSTRACT FROM AUTHOR]

• We report discovery, phylogeny, and genomic organization of monsavirus. • Phylogenetic analysis revealed the neighboring phylogenetic association with other posa-like virus, based on the conserved replication block of Hel-Pro-RdRp and core RNA-dependent RNA polymerase domain, showing significant separation compared with other known families. • The posa-like viruses harbored high amino acid diversity but similar genomic organization including the conserved replication block of Hel-Pro-RdRp, the same order of the genomic coding region, and picorna-like capsid domains. • We proposed a new family, Posaliviridae , within Picornavirales. Posa-like viruses have been detected in the fecal samples of several host species and are considered unclassified members of Picornavirales. Here, we identified genomic fragments of novel posa-like viruses (monsaviruses) in monkey specimens through next generation sequencing and obtained 11 full-length genomes. This monsavirus shared 88.5–89.2% nucleotide similarity with the Tottori-HG1 strain (GenBank accession LC123275). In total, 713 nucleotide polymorphism sites were identified, indicating their persistent evolution during circulation. The genomic organization and phylogenetic relationship of monsavirus were determined. Subsequent phylogenetic analysis of the conserved replication block of Hel-Pro-RdRp and core RNA-dependent RNA polymerase domain-based analysis of posa-like viruses showed significant separation compared with other known families. Further, posa-like virus genomes possessed the classical replication block of picornavirus in the 5′ part of genome and picorna-like capsid domains at the structural coding region of 3′ part of genome. Based on these results, we proposed the new family Posaliviridae, within Picornavirales. Four genera, which showed 68.6–75.5% amino acid distances but similar genomic organization including the conserved replication block of Hel-Pro-RdRp, the same order of the genomic coding region, and picorna-like capsid domains, were identified. The flexible genomic organization strategy and a large evolutionary scale of Posaliviridae was explicit. This study provides novel information on monsaviruses and important taxonomic data for the family Posaliviridae. [ABSTRACT FROM AUTHOR]