多糖亲水胶体对油炸外裹糊鱼块外壳特性与油脂渗透的影响

为探究多糖亲水胶体对油炸外裹糊鱼块外壳特性与油脂渗透的影响,将小麦淀粉与小麦面筋蛋白以11∶1的比例调匀后,分别加入0.3%的羧甲基纤维素钠(sodium carboxymethyl cellulose,CMC-Na)、0.2%的瓜尔胶(guar gum,GG)、0.2%的黄原胶(xanthan gum,XG)制得外裹糊。鱼块经裹糊挂糠后在170℃初炸40 s,190℃复炸30 s,测定外壳的荧光强度和表面疏水性、巯基和二硫键的含量、小麦面筋蛋白的二级结构和小麦淀粉的晶体结构,分析外壳中的油脂渗透。结果显示,添加3种多糖亲水胶体的外壳的表面疏水性、荧光强度、二硫键含量、β-折叠和β-转角的相对含量均大于对照(未添加多糖亲水胶体),而游离巯基含量、小麦淀粉的相对结晶度、α-螺旋和无规卷曲相对含量均小于对照。其中,添加XG的外壳的表面疏水性、荧光强度、巯基含量和小麦淀粉的相对结晶度、α-螺旋相对含量最低,其次是CMC-Na和GG。二硫键含量和β-折叠则呈现出相反的趋势。对照油炸外裹糊鱼块的苏丹红染色范围最大,添加XG的苏丹红染色范围最小(仅在外壳中),其次是CMC-Na和GG。这些结果表明,由于多糖亲水胶体较强的水结合能力和自身结构的独特性,能与小麦面筋蛋白相互作用,改善了外壳的稳定性,从而有效地抑制油炸外裹糊鱼块的油脂渗透。

考虑GIS外壳传输特性的VFTO计算模型

在计算快速暂态过电压(very fast transient overvoltage,VFTO)时,全封闭式组合电器(gas insulatedswitchgear,GIS)暂态电路的准确搭建直接影响VFTO的计算准确度。结合中国某1100kVGIS变电站,根据多导体传输线理论和相模变换方法,建立了GIS外壳传输特性模型,并与GIS内部暂态模型相结合,详细计算了隔离开关操作时所产生的VFTO,分析了GIS内部关键设备处VFTO的极值、频谱特性及上升率。最后研究了未操作相母线上残余电压对操作相VFTO的影响。研究结果可供GIS设计及连接在GIS上的电气设备绝缘结构设计参考。

Buckling analysis of the shell of a refuge chamber in a coal mine under uniform axial compression

A stiffened cylindrical shell is normally used in refuge chambers of a coal mine. Based on the method of application and shape characteristics of a refuge chamber, we simplified its shell as an orthotropic cylinder. The basic buckling equation of the stiffened cylindrical shell under uniform axial compression was deduced by using a Donnell function. The factors affecting its buckling capacity were studied by theoretical analysis and numerical calculations. The results reveal that the torsional rigidity of the longitudinal stiffener had little effect on the buckling capacity of the shell and that the critical load of an externally stiffened cylindrical shell is higher than that of an internally stiffened cylindrical shell.

Natural frequency characteristics of thin-walled homogeneous and manifold layered cylindrical shells under pressure using energy method

Energy method for the vibration of two types of cylindrical shells,namely thin-walled homogeneous isotropic and manifold layered isotropic cylindrical shells under uniform external lateral pressure is presented.The study is carried out based on strain-displacement relationship from Love's shell theory with beam functions as axial modal function.A manifold layered cylindrical shell configuration is formed by three layers of isotropic material where the inner and outer layers are stainless steel and the middle layer is aluminum.The homogeneous cylindrical shell is made-up of isotropic one layer with stainless steel.The governing equations with uniform external lateral pressure for homogeneous isotropic and manifold layered isotropic cylindrical shells are obtained using energy functional by the Lagrangian function with Rayleigh-Ritz method.The boundary conditions that are presented at the end conditions of the cylindrical shell are simply supported-simply supported,clamped-clamped and free-free.The influences of uniform external lateral pressure and symmetrical boundary conditions on the natural frequency characteristics for both homogeneous and manifold layered isotropic cylindrical shells are examined.For all boundary conditions considered,the natural frequency of both cylindrical shells with symmetric uniform lateral pressure increases as h/R ratio increases and those considering natural frequency of the both cylindrical shells with symmetric uniform lateral pressure decrease as L/R ratio increases.

Preparation of Ultrafine SiO2 Powder from Rice Husk and Properties of Its Infrared Spectrum

This paper discussed impact of temperature on the size distribution in preparing ultrafine silica from rice husk.The samples prepared were analyzed with infrared spectrum,and the relation between the particle size and intensity of characteristic absorption peak of IR at center around 1 100 cm-1 was disscussed with the baseline method.Results show that when the temperature is 650 ℃ and roasting time is 11 h,at optimal reaction conditions,the size distribution of the ultrafine silica powder prepared is relatively concentrated,and the average particle size is 199.5 nm.Moreover,the characteristic absorption band of IR is broadening gradually along with particle size decreasing.