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The effect of segregation defect of SiC particles on the properties of materials was studied. 15% SiCp/2009Al composites were prepared by powder metallurgy (PM). Special SiC/Al samples were added to 15% SiCp/2009Al composites. These SiC/Al samples with different sizes and volume fractions were 25%, 35%, 45% and 60%, respectively, which resulted in SiC particulates segregation defect. The 15% SiCp/2009Al composites with defects were tested by ultrasonic testing. Tensile samples were obtained at the locations, where defects might be detected and the mechanical properties were tested. The results showed that all defective samples were cracked at the defective location. The difference in tensile strength between the samples of defect and the samples without defect was large. The toughness of the sample containing the defect reduced and the brittleness increased. The dimples on the matrix indicate that ductile fracture occurred during the fracture process. The cleavage fracture or cracking of the SiC particulates indicated that the stress can be effectively transferred from the matrix to the particles, and the particulates strengthen the matrix well. However, the sample with defect led to brittle fracture in the defect, and a crack source produced at the interface, resulting in a significant decrease in the mechanical properties of the material. If the inhomogeneous distribution of particulate containing a large area was found in the ultrasonic testing of the aluminum matrix composites, the tensile properties of the products generally cannot meet the requirement for application.

This study focused on the effect of bone marrow mesenchymal stem cells (BMSCs) on the repair of rat liver injury induced by Cr (VI). Twenty-four Wistar rats were randomly divided into the control, model and cell therapy group, with 8 rats in each group. Potassium dichromate solution containing 0, 0.4 and 0.4 mg/kg·bw Cr (VI) was administered 5 times a week for 30 days. At the end of treatment, rats in the cell therapy group were administered 1 × 107 BMSCs. Two weeks later, serum alanine and aspartate aminotransferase levels in the cell therapy group were significantly improved compared with those in the model group, CM-Dil-labeled BMSCs were localized in rat livers. Compared with the model group, in the cell therapy group the number of apoptotic hepatocytes by TUNEL assay, MDA content, the expression of HIF-1α, endoplasmic reticulum (ER) stress-mediated apoptosis-related proteins including Grp78, CHOP, Cleaved-Caspase-12, ATF6, and Bax was significantly lower, and SOD activity, the expression of SIRT1 and Bcl-2 was significantly higher. It is suggested that BMSCs are localized in livers and reduce the toxic effects of Cr (VI) on the liver, and the possible mechanism may be related to the mechanisms of BMSCs decreasing ER stress-mediated hepatocyte apoptosis via the SIRT1/HIF-1α signaling pathway.

Supplemental Digital Content is available in the text, Background: In recent years, some studies indicated that repetitive transcranial magnetic stimulation (rTMS) could relieve neuropathic pain (NP) following a spinal cord injury (SCI), whereas some studies showed no pain relief effect. In addition, some studies showed the analgesic effect of transcranial direct current stimulation (tDCS) on NP post SCI, whereas other studies showed no effect. Methods: We systematically searched on the PubMed, Web of Science, EMBASE, Medline, Google Scholar for studies exploring the analgesic effect of rTMS or tDCS on NP post SCI until November 2019. Meta-analysis was conducted to summarize results of these studies. Results: The present quantitative meta-analysis indicated no significant difference in the effect of treatment on NP following SCI between rTMS and sham rTMS over the motor cortex at about 1 week after the end of the rTMS period (standardized mean difference (SMD) = 2.89, 95% confidence interval (CI) = −0.27 to 6.04). However, the study indicated that rTMS showed significantly better pain relief of treatment compared with sham rTMS between 2 and 6 weeks after the end of the rTMS period (SMD = 3.81, 95%CI: 0.80–7.52). However, no sufficient evidence could be provided to make a meta-analysis for the analgesic effect of tDCS on NP following SCI over the primary motor area (M1). Conclusions: In conclusion, the present meta-analysis suggested that rTMS did not show early analgesic effect on NP after SCI, but showed better middle-term analgesic effect, compared with sham rTMS. More large scale, blinded randomized controlled trials (RCTs) were needed to explore the analgesic effect of rTMS and tDCS on NP following SCI.

This paper introduces an asphalt mixture that mixed with different admixtures, rutting resistance agent and lignin fiber, at the same time. Rutting test and freeze-thaw splitting test are used to analyze rutting resistance on the high temperature and low temperature cracking of the asphalt mixture. The experiments with different mixes material composition are conducted to analysis various properties of the two admixtures on the mixture, especially the high temperature stability, low temperature crack resistance and the law of improvement effect. In addition, the experiments also determine the optimal asphalt content of different type of mixtures. The results showed that the single-doped KTL rutting resistance or lignin fibers have some improvement in water temperature performance of asphalt mixture, stability improvement of double-doped admixture asphalt mixture is better than the single-doped asphalt mixture, such as KTL rutting resistance agents and lignin fibers

The Game of the Amazons is a two-player territory game. It has attracted attentions in the research of computer game because of its simple rules and its complexity of play. In this paper, we construct and optimize an Amazons playing program X+, which is a new improvement on the search algorithm by using the game progress to modify search depths dynamically. In addition, a new evaluation factor is proposed and added to the evaluation function. After experimental verification, the improvements are proved to be effective, and have helped the program to win the second prize in the 2014 National Undergraduate Computer Games Competition.

Hardware-in-the-loop simulation is usually used to test its performance in the process of design of transfer aligment system. Many computers were used to set up hardware-in-the-loop simulation of distributed transfer aligment system, each computer undertook different simulation tasks, To improve the instantaneity and similarity of simulation system, simulation computers were connected through real-time network, flight rocker was adopted to simulate the flight of the plane more realistically, and it is convenient to do the motions on each axis. The component of hardware-in-the-loop simulation, the design of hardware interface, the design of software, and the algorithm of each slave system were discussed, meanwhile the working process of the system was introduced in detail, the solution of time delay in the system was proposed. The experiment shows that the hardware-in-the-loop simulation system is appropriately designed, stable and reliable, and has been applied in a certain plane simulation system.

The dc field dependencies of the ac susceptibility X'' have been studied in polycrystalline samples of YBa2+xCu3O7-y with x-values ranging from 0 to 0.2. Data on X'' versus T show the expected intergranular coupling peak at the temperature T-p. For a specific dc field T-p is found to increase with x varying from 0 to 0.10, and to decrease sharply at x > 0.10. Moreover, the transport critical current density J(ct) of samples increases with x up to 0.10. According to this evidence it can be concluded that a certain excess of barium in YBa2+xCu3O7-y improves the weak links at grain boundaries.

yang, zq (reprint author), acad sinica,inst met res,72 wenhua rd,shenyang 110015,peoples r china

Polycrystalline Bi1.8Pb0.4Sr2Ca2Cu3.2-xGexOy superconductors were prepared. The x-ray diffraction results show that all of the samples mainly consist of Bi-2223 and Bi-2212 phases. The relationship between the peak temperature T-p in the chi ''-T curve and the applied AC field H-ac shows that the T-p is linearly dependent on the H-ac for compounds with x less than or equal to 0.1, but non-linearly dependent on the H,, for the compounds with 0.1

BELARUSSIAN STATE POLYTECH ACAD,MINSK 220027,BYELARUS.;YANG, ZQ (reprint author), ACAD SINICA,INST MET RES,72 WENHUA RD,SHENYANG 110015,PEOPLES R CHINA