Neuroprotective Effect of Sonic Hedgehog Mediated PI3K/AKT Pathway in Amyotrophic Lateral Sclerosis Model Mice

The Sonic Hedgehog (SHH) signaling pathway is related to the progression of various tumors and nervous system diseases. Still, its specific role in neurodegenerative diseases, such as amyotrophic lateral sclerosis (ALS), remains studied. This research investigates the role of SHH and PI3K/AKT signaling pathway proteins on ALS development in a SOD1-G93A transgenic mouse model. After injection of SHH and PI3K/AKT signaling pathway inhibitors or agonists in hSOD1-G93A (9 weeks of age) transgenic mice, we studied skeletal muscle pathology using immunohistochemical staining and Western blot methods. In addition, recorded data on rotation time, weight, and survival were analyzed for these mice. Our study showed that the expression of SHH, Gli-1 and p-AKT in ALS mice decreased with the progression of the disease. The expression of p-AKT changed together with Gli-1 while injecting PI3K/AKT signaling pathway inhibitor or agonist; SHH and Gli-1 protein expression remained unchanged; p-AKT protein expression significantly decreased while injecting PI3K/AKT signaling pathway inhibitor. These results indicate that SHH has a regulatory effect on PI3K/AKT signaling pathway. In behavioral experiments, we found that the survival time of hSOD1-G93A mice was prolonged by injection of SHH agonist while shortened by injection of SHH inhibitor. In conclusion, we confirmed that the SHH pathway played a neuroprotective role in ALS by mediating PI3K/AKT signaling pathway

Phase stability and electronic structure of Si2Sb2Te5 phase-change material

Conference Name:5th International Conference on Study of Matter at Extreme Conditions. Conference Address: Miami, FL. Time:MAR 28-APR 02, 2009.On the basis of an ab initio computational study, the present work provide a full understanding on the atomic arrangements, phase stability as well as electronic structure of Si2Sb2Te5, a newly synthesized phase-change material. The results show that Si2Sb2Te5 tends to decompose into Si1Sb2Te4 or Si1Sb4Te7 or Sb2Te3, therefore, a nano-composite containing Si1Sb2Te4, Si1Sb4Te7 and Sb2Te3 may be self-generated from Si2Sb2Te5. Hence Si2Sb2Te5 based nano-composite is the real structure when Si2Sb2Te5 is used in electronic memory applications. The present results agree well with the recent experimental work. (C) 2010 Elsevier Ltd. All rights reserved

A phase-field formulation based on an extended F-criterion for rock fracture

In this paper a phase-field formulation based on an extended F-criterion (the normalized strain energy release rate criterion) is proposed to simulate tensile-compressive-shear rock fractures. By applying the F-criterion, the phase-field crack-driving energy decomposition is determined by a direction search which maximizes the local fracture dissipation. In compressive-shear states, the computation is supplemented by an explicitly expressed confinement-dependent mode-II fracture energy release rate, and the cracking angle is determined by both the fracture energy and strain states. The hybrid formulation and alternate minimization algorithm are adopted for the numerical examples in this paper. Fractures for rock and rock-like specimens subjected to compression demonstrate the ability of the present model in capturing tensile-compressive-shear rock fracture behaviors

Bio-Mediated Method for Immobilizing Copper Tailings Sand Contaminated with Multiple Heavy Metals

Microbial induced carbonate precipitation (MICP) is a natural bio-mediated process that has been investigated for soil stabilization and heavy metal immobilization in soil and groundwater. This study analyzed the effect and mechanism of MICP for the solidification/stabilization of tailings sand with multi-heavy metals. When the concentration of cementation solution (CS) is 1.0 mol/L and the optical density(OD600) is 1.6, the unconfined compressive strength of tailings sand treated by MICP is the largest, and the solidification efficiency of heavy metals in tailings sand is also the highest. The macroscopic and microscopic observations reveal that the mechanism of MICP solidification of tailings is bacterial outer oxide, hydroxide, alkaline carbonate, and carbonate precipitation

Bio-Mediated Method for Immobilizing Copper Tailings Sand Contaminated with Multiple Heavy Metals

Microbial induced carbonate precipitation (MICP) is a natural bio-mediated process that has been investigated for soil stabilization and heavy metal immobilization in soil and groundwater. This study analyzed the effect and mechanism of MICP for the solidification/stabilization of tailings sand with multi-heavy metals. When the concentration of cementation solution (CS) is 1.0 mol/L and the optical density(OD600) is 1.6, the unconfined compressive strength of tailings sand treated by MICP is the largest, and the solidification efficiency of heavy metals in tailings sand is also the highest. The macroscopic and microscopic observations reveal that the mechanism of MICP solidification of tailings is bacterial outer oxide, hydroxide, alkaline carbonate, and carbonate precipitation

Pt Modified Sb₂Te₃ Alloy Ensuring High−Performance Phase Change Memory

Phase change memory (PCM), due to the advantages in capacity and endurance, has the opportunity to become the next generation of general−purpose memory. However, operation speed and data retention are still bottlenecks for PCM development. The most direct way to solve this problem is to find a material with high speed and good thermal stability. In this paper, platinum doping is proposed to improve performance. The 10-year data retention temperature of the doped material is up to 104 °C; the device achieves an operation speed of 6 ns and more than 3 × 105 operation cycles. An excellent performance was derived from the reduced grain size (10 nm) and the smaller density change rate (4.76%), which are less than those of Ge2Sb2Te5 (GST) and Sb2Te3. Hence, platinum doping is an effective approach to improve the performance of PCM and provide both good thermal stability and high operation speed

Local atomic structure in molten Si3Sb2Te3 phase change material

National Integrate Circuit Research Program of China [2009ZX02023-003]; National Key Basic Research Program of China [2010CB934300, 2011CBA00602, 2011CB932800]; National Natural Science Foundation of China [60906004, 60906003, 61006087, 61076121]; Science and Technology Council of Shanghai [1052nm07000]; Supercomputing Center, CNIC, CASBy means of ab initio molecular dynamics calculations, we have studied the local structures of liquid and amorphous Si3Sb2Te3. The results show that all the constitute elements in liquid Si3Sb2Te3 are octahedrally coordinated. While in amorphous state, Sb and Te atoms are mainly octahedrally coordinated and Si atoms are mainly tetrahedrally coordinated. In both states, Si is mainly homo-bonded by Si. Finally, we proposed a phase separation model for liquid and amorphous Si3Sb2Te3, which is responsible for the good performance of Si3Sb2Te3 alloy as a phase change material. (C) 2011 Elsevier Ltd. All rights reserved

Ab initio study of Sb2SexTe3-x(x=0, 1, 2) phase change materials

National Integrate Circuit Research Program of China [2009ZX02023-3]; National Basic Research Program of China [2007CB935400, 2010CB934300, 2006CB302700]; National High Technology Development Program of China [2008AA031402]; Science and Technology CouncilBy means of ab lain total energy calculations, we have investigated the structure and properties of Sb2SexTe3-x (x = 0, 1, 2) alloys, a family of phase change materials for data storage. On the basis of analyzing the chemical bonding and electronic properties of Sb2SexTe3-x (x = 1, 2) and Sb2Te3 alloys, we have shown that the crystalline-to-amorphous transition of Sb2Se2Te may be faster than that of Sb2Te3. Furthermore, the substitution of Te by Se in Sb2Te3 can increases the electric resistance of Sb2SexTe3-x (x = 1, 2) alloys and hence may lower the reset power consumption. (C) 2010 Elsevier Masson SAS. All rights reserved

Ab initio study of antisite defective layered Ge2Sb2Te5

By means of ab initio calculations, we have investigated the antisite defects in layered Ge2Sb2Te5 (GST). Our results show that both Te-sb and Sb-Te antisite defective GST alloys are energetically favorable and mechanically stable. Furthermore, the presence of antisite defects results in the decrease in band gaps and hence the increase in the electrical conductivity, while shows slight effect on chemical bonding characters. Based on the present results, increased electrical conductivity and decreased thermal conductivity are expected by introducing antisite defects in GST related layered materials. (C) 2012 Elsevier B.V. All rights reserved.National Natural Science Foundation of China [60976005]; program for New Century Excellent Talents in University [NCET-08-0474]; Outstanding Young Scientists Foundation of Fujian Province of China [2010J06018

Pressure-induced topological insulating behavior in the ternary chalcogenide Ge2Sb2Te5

National Natural Science Foundation of China [60976005]; Outstanding Young Scientists Foundation of Fujian Province of China [2010J0103]; program for New Century Excellent Talents in University [NCET-08-0474]We unraveled the pressure-induced topological insulating behavior in Ge2Sb2Te5 (GST) by means of ab initio calculations. We have shown that the spin-orbit interaction separates the twofold degenerate Ge p(x)p(y) Sb p(x)p(y) Te p(x)p(y) state to an upper and a lower level and enhances the energy level of Ge s Sb s Te p(z)/Ge p(z) Sb p(z) Te s states. Consequently, the sign of parity changes by inversing the characterizations of conduction band minimum and valence band maximum in a certain range of pressures. Moreover, the surface band structure with the Dirac cone feature was observed. The present results suggest that GST-relatedmaterials are a new family of pressure-induced topological insulators