Formation of Corrugated Damage on Bearing Race under Different AC Shaft Voltages.

Corrugated damage to bearings is a common fault in electrical facilities such as new energy vehicles, wind power, and high-speed railways. The aim of this article is to reveal the microscopic characteristics and formation mechanism of such damages. The corrugation with alternating "light" and "dark" shape was produced on GCr15 bearing races in the experimental conditions. Compared to the light area, the dark area (in the images generated by optical microscope) has more severe electrical erosion, lower hardness, more concave morphology, and lower oxidation. As the voltage increases, the width of the corrugation, the height difference between corrugation, and surface roughness all increase. It is believed that the formation of corrugated damage requires a sufficiently high voltage to induce the periodic destruction and reconstruction of the lubrication film. When the bearing is in a metal-lubrication film-metal contact state, the high voltage causes the lubrication film to break down and induce electrical erosion. Then, the contact area is in metal-metal contact, and the surface is mainly damaged by mechanical rolling. After the reconstruction of lubrication film, the next round of electrical erosion begins. The results are helpful for a deeper understanding of the mechanism of bearing erosion in electrical application.

Enhanced Electrical Conductivity of (001) Oriented Sr0.9La0.1TiO3 Microplatelets for Thermoelectric Applications.

Two-dimensional perovskite microplatelets have played an important role in various applications, especially acting as a template to guide grains' epitaxial growth in the preparation of textured ceramics. The (001) oriented Sr0.9La0.1TiO3 microplatelets with a high aspect ratio of ∼20 were synthesized and obtained from Aurivillius Bi4Ti3O12 precursors. To reveal the mechanism of topochemical microcrystal conversion of Bi4Ti3O12 to Sr0.9La0.1TiO3, the reaction interface, morphology development, and phase composition evolution of the (001) oriented Sr0.9La0.1TiO3 microplatelets were investigated. When the temperature of the molten salt is above 753 °C, multiple Sr0.9La0.1TiO3 topological nucleation events took place. At 950 °C, the polycrystalline aggregate of (001)-oriented Sr0.9La0.1TiO3 crystallites grew in place of the original single crystal Bi4Ti3O12 platelets. When the temperature reached 1150 °C, the Sr0.9La0.1TiO3 platelets preserved the shape of a high aspect ratio and exhibited not only enhanced electrical conductivity with a carrier concentration of 3.518 × 1020 cm-3 and carrier mobility of 8.460 cm2·V-1·s-1 but also significantly decreased thermal conductivity ranging from 5.65 W·m-1·K-1 at 300 K to 2.54 W·m-1·K-1 at 1073 K. It can be widely applied in the field of template grain growth methods for preparing textured thermoelectric ceramics to improve their thermoelectric properties.

Enhanced Energy Storage Properties in Lead-Free (Na0.5Bi0.5)0.7Sr0.3TiO3-Based Relaxor Ferroelectric Ceramics through a Cooperative Optimization Strategy.

Although relaxor ferroelectrics have been widely investigated owing to their various advantages, there are still impediments to boosting their energy-storage density (Wrec) and energy-storage efficiency (η). In this paper, we propose a cooperative optimization strategy for achieving comprehensive outstanding energy-storage performance in (Na0.5Bi0.5)0.7Sr0.3TiO3 (NBST)-based ceramics by triggering a nonergodic-to-ergodic transformation and optimizing the forming process. The first step of substituting NaNbO3 (NN) for NBST generated an ergodic state and induced polar nanoregions under the guidance of a phase-field simulation. The second step was to apply a viscous polymer process (VPP) to the 0.85NBST-0.15NN ceramics, which reduced porosity and increased compactness, resulting in a significant polarization difference and high breakdown strength. Consequently, 0.85NBST-0.15NN-VPP ceramics optimized by this cooperative two-step strategy possessed improved energy-storage characteristics (Wrec = 7.6 J/cm3, η = 90%) under 410 kV/cm as well as reliable temperature adaptability within a range of 20-120 °C, outperforming most reported (Na0.5Bi0.5) TiO3-based ceramics. The improved energy-storage performance validates the developed ceramics' practical applicability as well as the advantages of implementing a cooperative optimization technique to fabricate similar high-performance dielectric ceramics.

Minor and major circRNAs in virus and host genomes.

As a special type of noncoding RNA, circular RNAs (circRNAs) are prevalent in many organisms. They can serve as sponges for microRNAs and protein scaffolds, or templates for protein translation, making them linked to cellular homeostasis and disease progression. In recent years, circRNAs have been found to be abnormally expressed during the processes of viral infection and pathogenesis, and can help a virus escape the immune response of a host. Thus, they are now considered to play important functions in the invasion and development of viruses. Moreover, the potential application of circRNAs as biomarkers of viral infection or candidates for therapeutic targeting deserves consideration. This review summarizes circRNAs in the transcriptome, including their classification, production, functions, and value as biomarkers. This review paper also describes research progress on circRNAs in viral infection (mainly hepatitis B virus, HIV, and some human herpes viruses) and aims to provide new ideas for antiviral therapies targeting circRNAs.

Enhancement of Thermoelectric Performance of Sr0.9La0.1TiO3-Based Ceramics Regulated by Nanostructures.

La-doped strontium titanite (Sr0.9La0.1TiO3) is a promising candidate for n-type oxide thermoelectric materials. However, the ZT values of this material are low, leading to low conversion efficiency. Improvements in this efficiency are required. In this work, a high ZT value of 0.50 was obtained for Sr0.9La0.1TiO3 ceramic samples by adding 10 wt % Bi2O3 sintering aids and 20 wt % nanosized Ti powders to the matrix material. Although Ti was oxidized to TiO2 during the sintering process, nanoscale phase interfaces were beneficial for phonon scattering and thermal conductivity reduction. Nanosized metallic Bi and Bi2O3 particles were observed. These two factors played an important role in reducing the thermal conductivity from 2.5 W/(m K) at room temperature to 1.31 W/(m K) at 1073 K. Nanostructure control using nanosized metal powders as additives combined with the Bi2O3 sintering aid paves a way for enhancement of thermoelectric properties of oxide thermoelectric materials.

Kartogenin enhances the therapeutic effect of bone marrow mesenchymal stem cells derived exosomes in cartilage repair.

The effectiveness of mesenchymal stem cells (MSC) in the treatment of cartilage diseases has been demonstrated to be attributed to the paracrine mechanisms, especially the mediation of exosomes. But the exosomes derived from unsynchronized MSCs may be nonhomogeneous and the therapeutic effect varies between samples. Aim: To produce homogeneous and more effective exosomes for the regeneration of cartilage. Materials & methods: In this study we produced specific exosomes from bone marrow MSCs (BMSC) through kartogenin (KGN) preconditioning and investigated their performance in either in vitro or in vivo experiments. Results & conclusion: The exosomes derived from KGN-preconditioned BMSCs (KGN-BMSC-Exos) performed more effectively than the exosomes derived from BMSCs (BMSC-Exos). KGN preconditioning endowed BMSC-Exos with stronger chondral matrix formation and less degradation.

Parallel Simulated Annealing Using an Adaptive Resampling Interval.

This paper presents a parallel simulated annealing algorithm that is able to achieve 90% parallel efficiency in iteration on up to 192 processors and up to 40% parallel efficiency in time when applied to a 5000-dimension Rastrigin function. Our algorithm breaks scalability barriers in the method of Chu et al. (1999) by abandoning adaptive cooling based on variance. The resulting gains in parallel efficiency are much larger than the loss of serial efficiency from lack of adaptive cooling. Our algorithm resamples the states across processors periodically. The resampling interval is tuned according to the success rate for each specific number of processors. We further present an adaptive method to determine the resampling interval based on the adoption rate. This adaptive method is able to achieve nearly identical parallel efficiency but higher success rates compared to the fixed interval one using the best interval found.