介孔分子筛表面功能膜的制备及对水体中铅汞镉的去除作用

表面改性;功能膜材料;重金属;吸附;介孔分子筛表面功能膜的制备及对水体中铅汞镉的去除作用     

菠菜部分成分的实验探究

以民间关于菠菜的种种说法作为学生研究性学习的基础,介绍了学生在讨论的基础上对菠菜的部分成分进行的定性和定量实验,并对相关实验提出了建议。     

苯甲醛肟与炔丙醇偶极环加成反应的理论研究

用密度泛函理论(DFT)方法在B3LYP/6-31G*水平上研究了苯甲醛肟与炔丙醇加成反应的微观机制和热力学、动力学行为. 结果表明, 在苯甲醛肟与炔丙醇加成反应过程中, 8个可能反应通道的过渡态中均形成非平面五元环结构, 其中苯甲醛肟的Z、E构型特征得到了部分保留, 但主要部分的键长、键角均发生了变化, 电荷也进行了重新分布. 苯甲醛肟以羟基型参与反应的4个反应通道均为吸热反应和热力学非自发过程, 它们均具有较高的反应势垒、较慢的反应速率和较小的平衡常数; 而以离子型参与反应的四个反应通道均为放热反应和热力学自发过程, 它们的反应势垒较低, 反应速度较快, 平衡常数也较大, 故苯甲醛肟应主要以离子型参与反应. 炔丙醇的两种取向对应着加成反应的两种产物, 反应达到平衡后, 3-羟甲基二氢异噁唑为主要产物.     

Computer simulation of symmetrical tilt grain boundaries in noble metals with MAEAM

This paper reports that an atomic scale study of [\bar {1}10] symmetrical tilt grain boundary (STGB) has been made with modified analytical embedded atom method (MAEAM) for 44 planes in three noble metals Au, Ag and Cu. For each metal, the energies of two crystals ideally joined together are unrealistically high due to very short distance between atoms near the grain boundary (GB) plane. A relative slide between grains in the GB plane results in a significant decrease in GB energy and a minimum value is obtained at specific translation distance. The minimum energy of Cu is much higher than that of Ag and Au, while the minimum energy of Ag is slightly higher than that of Au. For all the three metals, the three lowest energies correspond to identical (111), \mbox(113) and \mbox(331) boundary successively for two translations considered; from minimization of GB energy, these boundaries should be preferable in [\bar {1}10] STGB for noble metals. This is consistent with the experimental results. In addition, the minimum energy increases with increasing reciprocal planar coincidence density \Sigma, but decreases with increasing relative interplanar distance d /a.     

茵陈挥发油GC-MS指纹图谱分析

建立了茵陈挥发油GC-MS指纹图谱,将正交投影算法用于不同样本中共有峰的提取,提高了共有峰的识别能力,降低了由于保留时间的漂移、质谱检索匹配度不高以及色谱峰重叠而引起的共有峰识别的难度.采用共有峰率、变异率及相似度等几个指标对4个不同产地的茵陈挥发油成分进行了评价,从共性、差异和整体性等多个方面全面表征茵陈挥发油的化学模式特征.结果表明,不同产地的茵陈挥发油成分大致相同,该指纹图谱可用于茵陈中挥发油成分的质量控制.     

QCM和SAW传感器的原理及其在现场检测中的应用

压电化学传感器是一类重要的质量敏感型检测器,由于具有体积小、灵敏度高、响应时间快等优越性而具有极好的应用前景.本文介绍了体声波化学传感器(QCM)和表面声波化学传感器(SAW)的原理,概述了最近几年的应用情况及提高灵敏度的方法,并对其发展趋势进行了展望.     

功能化多壁碳纳米管的光电性质

表面光电压谱;循环伏安;金刚石薄膜电极;功能化多壁碳纳米管的光电性质     

全氟磺酸锂电导率式湿度传感器

以碳纸为电极,Nafion溶液再铸薄膜为感湿材料,并用氯化锂将膜转换成Li+型,制备了固体聚合物电解质湿度传感器.测定了不同相对湿度下,传感器的电导率响应与相对湿度之间关系.结果表明:在相对湿度为10%～97%范围内,传感器的电导率响应对数与相对湿度之间成良好的线性关系,线性度为0.997;传感器响应的时间为40s左右;于200h内稳定性和重复性良好.     

Calculation of the surface energy of fcc metals with modified embedded-atom method

The surface energies for 38 surfaces of fcc metals Cu, Ag, Au, Ni, Pd, Pt, A1, Pb, Rh and Ir have been calculated by using the modified embedded-atom method. The results show that, for Cu, Ag, Ni, A1, Pb and Ir, the average values of the surface energies are very close to the polycrystalline experimental data. For all fcc metals, as predicted, the close-packed (111) surface has the lowest surface energy. The surface energies for the other surfaces increase linearly with increasing angle between the surfaces (hkl) and (111). This can be used to estimate the relative values of the surface energy.     

THz-field-induced electronic transmission step-structure for a quantum wire

We study theoretically the low-temperature electronic transport property of a straight quantum wire under the irradiation of a finite-range transversely polarized external terahertz (THz) electromagnetic (EM) field. Using the freeelectron model and the scattering matrix approach, we show an unusual behaviour of the electronic transmission of this system. A sharp step-structure appears in the electronic transmission probability as the EM field strength increases to a threshold value when a coherent EM field is applied. We demonstrate that this effect physically comes from the inelastic scattering of electrons with lateral photons through intersubband transitions.