Ischemia occurs in the brain as the result of stroke and other related injuries and few therapies are effective. If more is understood then potential treatments could be investigated. It was previously reported that 14-3-3gamma could be up-regulated by ischemia in astrocyte to protect cells from ischemia-induced apoptosis. In this study, we attempted to uncover the mechanism responsible for this 14-3-3gamma up-regulation in primary culture of astrocytes under ischemic-like conditions. It was found that in vitro ischemia may activate PI3K/Akt and MAPK signaling pathways. Astrocyte cultures were treated with LY294002 (PI3K inhibitor), U0126 (ERK inhibitor), SB203580 (p38 inhibitor) and SP600125 (JNK inhibitor). Only SP600125 could inhibit the ischemia-induced 14-3-3gamma up-regulation in astrocytes. At the same time, we observed an ischemia-induced nuclear translocation of p-c-Jun, a major downstream component of JNK. Inhibition of AP-1 with curcumin also inhibited 14-3-3gamma up-regulation indicating that ischemia-induced up-regulation of 14-3-3gamma in astrocyte involves activation of the JNK/p-c-Jun/AP-1 pathway.

No abstract

In this study, Si3N4 was bonded to Inconel600 with Nb/Cu/Ni interlayer by partial liquid phase diffusion bonding method under vacuum condition. The bonding temperature, bonding time, bonding pressure and cooling velocity was 1403K, 50min, 7.5MPa and 5K/min, respectively. The effects of interlayer thickness on the strength and fracture behaviors of joint were investigated through evaluating the strength of joints based on shear test and observing the fracture morphology by means of SEM. The results showed that the shear strength of joint changed with variation of the interlayer thickness. When the shear strength of joint increased, the location of fracture was changed from the ceramic/interlay interface to the reaction layer.

In friction surfacing process, the temperature field and strain field, especially of coating rod, is considered an important element in analyzing the process’ mechanism and choosing the key process parameters properly. In this paper, the finite element method was employed to simulate the coupling of 3-D temperature field and deformation field of coating rod during friction surfacing. The simulation results show that at the preliminary preheating period, the isotherm goes down at the center part, and the temperature field presents “M” along the radial direction. The temperature increasing rate at the friction interface is higher at first, and then become lower, once the friction system becomes quasi-steady, the temperature here will be stable approximately. The largest effective strain occurs near the center of bottom circle. The simulation results are close to the experimental results, thus builds a basis for analyzing the process’s mechanism, allows for theoretical guidance for analyzing feasibility and helps optimize key parameters.

Shear strength and fracture behavior of Al2O3 matrix ceramic composite brazed joints to carbon steel with Ag-Cu-Ti brazing alloy in flow argon have been studied by means of SEM, EDX and all-purpose testing machine. Results have shown that there is a close relationship between the shear strength and the fracture form of brazed joints. The fracture occurring completely in the composite near the composite/filler metal interface corresponds to the low strength of a joint, and the strength of the joint fractured partially in the composite usually increases with decreasing the proportion of the composite on the fracture surface in the steel side. When the fracture occurs in the reaction layer between the composite and the filler metal, the closer the fractured position comes to the composite/reaction layer interface, the higher the joint strength. The maximum shear strength is obtained when the fracture occurs fully at the interface.