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This paper studies the best tempering process and provides guidance for the industrial application of modified Al-bearing high boron high-speed steel (AB-HSS) in the future. The microstructure, har...

In this paper, the discoloration of the solder after the vacuum sintering of the power chip is analyzed. The morphology and composition of the discoloration area were characterized and analyzed by the metallographic microscope, SEM, EDS and XPS, and the discoloration mechanism was studied. The analysis results show that the main components of the color-changing solder are C, O, Pb, Sn, Ni, Ag, and Au, which are the normal components of the solder after vacuum sintering. The reason for color-changing is the oxidation of the Sn element, and the different thickness of oxide shows different colors. The discoloration solder was treated with formic acid, and the solder returned to bright silver-white. The test further confirmed that the discoloration was caused by metal oxidation. The problem of solder discoloration is solved by optimizing the process to reduce the sintering time and vacuum defoaming time.

In this paper, the effects of different quenching temperatures on the microstructure, hardness, and wear resistance of modified Al-bearing high boron high speed steel were investigated by means of optical microscopy (OM), scanning electron microscopy (SEM), X-ray diffraction (XRD), a hardness tester, and an MM-200 block-on-ring wear testing machine. The results showed that the as-cast microstructure of modified Al-bearing high boron high speed steel consisted of martensite, ferrite, pearlite and continuous network eutectic borocarbides which were distributed at the grain boundary. The eutectic borocarbides mainly included M2B and M7(C, B)3. With an increase of quenching temperature, the matrix turned into martensite, and the continuous network structure of eutectic borocarbides were gradually broken and changed to the spherical; the secondary borocarbides M23(C, B)6 were precipitated from the matrix. After quenching at 1150 °C, eutectic borocarbides were clearly visible as a broken network and spheroidal in shape, and the distribution was more uniform. When the quenching temperature was in a range of 1000 °C to 1150 °C, the hardness and wear resistance of the alloy obviously increased. When the quenching temperature attained 1150 °C, hardness reached the highest 64.3 HRC, and the wear resistance was best.

Multiple sclerosis (MS) is a chronic inflammatory disease of the CNS characterized by demyelination and axonal damage. Experimental autoimmune encephalomyelitis (EAE) is a well-established animal model for human MS. Although Th17 cells are important for disease induction, Th2 cells are inhibitory in this process. In this article, we report the effect of a Th2 cell product, extracellular matrix protein 1 (ECM1), on the differentiation of Th17 cells and the development of EAE. Our results demonstrated that ECM1 administration from day 1 to day 7 following the EAE induction could ameliorate the Th17 cell responses and EAE development in vivo. Further study of the mechanism revealed that ECM1 could interact with αv integrin on dendritic cells and block the αv integrin–mediated activation of latent TGF-β, resulting in an inhibition of Th17 cell differentiation at an early stage of EAE induction. Furthermore, overexpression of ECM1 in vivo significantly inhibited the Th17 cell response and EAE induction in ECM1 transgenic mice. Overall, our work has identified a novel function of ECM1 in inhibiting Th17 cell differentiation in the EAE model, suggesting that ECM1 may have the potential to be used in clinical applications for understanding the pathogenesis of MS and its diagnosis.

The surface morphology of ZnO films at different annealing temperatures and the performance of polymer solar cells (PSCs) with ZnO as the electron transport layer are studied. The low temperature sol-gel processed ZnO film has smoother surface than that in higher temperature, which results in the best photovoltaic performance with a power conversion efficiency (PCE) of 3.66% for P3HT:PC61BM based solar cell. With increasing annealing temperature, the photovoltaic performance first deceases and then increases. It could be ascribed to the synergy effects of interface area, the conductivity and surface energy of ZnO film and series resistance of devices.