盾构刀盘系统界面载荷力学表征与近似计算模型

针对地下隧道施工重型盾构装备,提出了一种刀盘系统界面载荷的力学表征与近似计算方法.在刀盘系统与掘进界面岩土间相互作用的解耦分析基础上,引入岩土屈服破坏效应的影响,修正了掘进界面边缘区域应力集中的问题,给出了刀盘系统界面载荷沿半径方向非线性分布的规律.考虑到实际施工中的地质条件、掘进进尺、刀盘拓扑结构,以及地下埋深等因素对掘进载荷的影响,建立了刀盘系统推力与扭矩的综合分析与计算模型,实现了地质力学性能、装备掘进状态、装备结构特征3类关键因素与掘进载荷间相互影响规律的力学描述;结合天津地铁工程实例,分析与验证了界面载荷模型的有效性.      

荧光二氧化硅纳米颗粒的制备、修饰及细胞成像分析

在微乳液体系中合成荧光二氧化硅纳米颗粒(FSNPs),然后对其表面进行氨基修饰,之后再连接抗体,应用高分辨透射电镜(HR-TEM),原子力显微镜(AFM),Zeta-电位分析仪,IR,荧光显微镜及激光共聚焦显微镜等多种表征工具对合成的颗粒和后续的修饰进行了系统分析.研究表明,FSNPs在溶液中呈现单分散状态,但是在表面...     

Magnetic transition behavior of perovskite manganites Nd_(0.5)Sr_(0.3)Ca_(0.2)MnO_3 polycrystalline

A polycrystalline sample Nd_(0.5)Sr_(0.3)Ca_(0.2)MnO_3 is prepared by the conventional solid state reaction method. The structure and magnetic properties are investigated with x-ray diffraction(XRD) patterns, a superconducting quantum interference device(SQUID), and electron spin resonance(ESR). The sample is in single phase with the space group Pbnm symmetry. With the decrease of temperature, Nd_(0.5)Sr_(0.3)Ca_(0.2)MnO_3 undergoes three magnetic transitions: ferromagnetic transition at TC≈ 210 K, charge-ordering at TCO≈ 175 K, and antiferromagnetic transition at TN= 155 K. In addition, the activation energy Ea ≈ 52.78 me V can be extracted by curve fitting.     

Electron spin resonance study of the Ba-doping manganite Nd0.5Sr0.5MnO3

We have performed magnetization measurements and electron spin resonance （ESR） on polycrystalline manganites of Nd0.5Sr0.5-xBaxMnO3 （x = 0.1）. Phase separation and phase transitions are observed from the susceptibility and the ESR spectra data. Between 260 K （～ Tc） and 185 K （～ TN）, the system coexists of the paramagnetic phase and the ferromagnetic （FM） phase. Between 185 K and 140 K, the system coexists of the FM phase and the antiferromagnetic （AFM） phase. These results indicate that the system has a very complex magnetic state due to the origin of the instability stemming from manganite Nd0.5Sr0.4Ba0.1MnO3 by partially substituting the larger Ba^2＋ ions for the smaller Sr^2＋ ions.     

氢化物发生中高浓度钴对砷锑铋测定的影响及消除

研究了高浓度钴对砷、锑、铋氢化物发生的影响,通过提高溶液酸度和加入大量的硫脲-抗坏血酸-盐酸羟胺作为还原掩蔽剂的办法消除高浓度基体对测定的影响,实现了氢化物发生原子荧光光谱法直接测定氧化钴中的痕量砷、锑、铋,无需基体分离或基体匹配,方法简便快速.检出限(S/N=3):砷0.29 μg/L,锑0.26 μg/L,铋0.24 μg/L;回收率为90% ～114%;样品分析相对标准偏差为2.1% ～9.8%(n=5).