Temperature dependence of microwave dielectric performance of silica

The dielectric properties of silica at temperature from 300 to 1 600K and at microwave frequency band are investigated. By use of material studio software, the lattice constant, band energy gap and optical permittivity of silica are calculated, and to be used as the key parameters to investigate the microwave dielectric properties of silica. It is found that its permittivity and loss are increased with increasing temperature. In addition, the ionic conduction loss caused by the defects in silica is very small from the calculation and the value is about 10^?5 level at 2 000K. The application of this analysis allows to estimate the permittivity and dielectric loss of silica both at high temperature and microwave band, which is currently still difficult to be measured directly.     

CT-1、NF-κBP65在心肌梗死大鼠心室重塑中的表达及罗格列酮的作用

目的观察罗格列酮对心肌梗死后大鼠心室重塑过程中CT-1、NF-κBP65表达的影响。方法通过结扎左冠状动脉前降支(LAD),随机选择40只雄性Wistar大鼠建立急性心肌梗死模型作为心肌梗死组,以假手术组(丙组,n=15)为对照。结扎术后1 d,心肌梗死组再随机分为罗格列酮干预组(甲组,n=20)及心肌梗死对照组(乙组,n=20)。此后8周,每日以4 mg/kg罗格列酮灌胃处理甲组大鼠,并以等量生理盐水处理乙组、丙组大鼠。通过Real-time PCR法、免疫组化法分别检测非梗死区CT-1 mRNA及NF-κBP65蛋白的表达。结果干预8周后,非梗死区心肌中CT-1mRNA、NF-κBP65的表达及左心室重量指数,乙组均高于甲、丙组,而甲、丙两组相比,甲组显著高于丙组,且均具有统计学意义(P<0.05)。结论罗格列酮逆转大鼠心肌梗死后心室重塑可能同抑制CT-1 mRNA及NF-κBP65蛋白的表达有关。     

桩板墙、悬臂墙在膨胀土路基中的应用

以安康东站油库专用线改造工程路基支挡设计为依托,进行膨胀土地区路堤支挡结构的设计,充分考虑膨胀土地区支挡的致灾机理和支挡结构的受力变形特征。刚性支挡结构和柔性支挡结构的结合使用,使得功能和经济效益达到共赢。