改进型验证相对论效应实验装置

验证相对论效应实验装置能够形象直观而又方便地验证快速电子的能量与动量的相对论关系．近年来的重新设计和改进在保留原有优点和特色的基础上改进了原装置的不足，突出了综合型、设计型的特点，真正达到了一机多用的目的，符合面向二十一世纪物理实验教学改革的趋势和方向．     

Quantitative Determination of Proteins Based on Strong Fluorescence Enhancement in Curcumin-Chitosan-Proteins System

We found that the fluorescence intensity of curcumin (CU) can be highly enhanced by protein bovine serum albumin (BSA) and human serum albumin (HSA) in the presence of chitosan (CTS). Based on this finding, a new fluorimetric method to determine the concentration of protein was developed. Under optimized conditions, the enhanced intensities of fluorescence are quantitatively in proportion to the concentrations of protein in range of 0.007-100 μg·mL(-1) for BSA and 0.004-100 μg·mL(-1) for HSA at 426 nm excitation, and 0.007-100 μg·mL(-1) for BSA and 0.01-100 μg·mL(-1)for HSA at 280 nm excitation, while corresponding qualitative detection limits (S/N = 3) can lower to 3.96, 2.46, 4.56, 9.20 ng·mL(-1), respectively. The method has been successfully used for the determination of HSA in real samples. Based on resonance light scattering and UV-visible absorption spectroscopic analysis, mechanism studies suggested that the highly enhanced fluorescence of CU was resulted from synergic effects of favorable hydrophobic microenvironment provided by BSA and CTS and efficient intermolecular energy transfer between BSA and CU. Protein BSA may bind to CTS through hydrogen bonds, which causes the protein conformation to convert from β-fold to α-helix. CU can combine with the BSA-CTS complex through its center carbonyl carbon, and CTS plays a key role in promoting the energy transfer process by shortening the distance between BSA and CU.     

Foaming and Damping Properties of Ethylene Vinyl-Acetate Copolymer/Polylactic Acid Blends

With ethylene vinyl-acetate copolymer (EVM) and polylactic acid (PLA) blends as the matrix, dicumyl peroxide (DCP) as the curing agent and azodicarbonamide (AC) as the foaming agent, EVM/PLA foamed blends were prepared by compression molding. The effects of different amounts of AC, DCP, and silica, as well as varying foaming time, on the cell structure and damping properties of the EVM/PLA-foamed blends were examined by scanning election microscopy (SEM) and dynamic mechanical analysis (DMA). The results showed that the cell size and damping properties varied little with increasing AC content in the compounds; however, the cell size declined slightly as DCP increased and the damping properties rose slightly, exhibiting an optimum set of properties at 5 phr of DCP. The cell size declined dramatically and damping increased significantly as the foaming time was increased. Moreover, both suddenly increased after 5 min foaming. It was found that the damping properties of the foamed materials increased with decreasing cell size and increasing number of cells. The cell size also decreased and damping properties increased as the silica content was increased. The silica interacted more strongly with EVM than with PLA.     

土壤中汞赋存形态及迁移转化规律研究进展

对汞污染的来源、危害、在土壤中的赋存形态、迁移转化规律及其影响因素进行了综述,在此基础上简要介绍了土壤汞污染的治理,提出了存在的问题和有待进一步研究的方向。     

组织模型偏振后向散射差分光谱的测量

建立了一套用于测量生物组织模型偏振后向散射差分光谱的实验系统。在系统中,线偏振光入射到样品表面,检偏器和光谱仪配合记录后向散射光中的平行和垂直分量,随后计算出差分光谱。采用了平均直径分别为5.0μm、9.0μm的两种聚乙烯小球悬浮液进行实验,结果与蒙特卡罗模拟进行对照,验证了实验系统的正确性。初步研究了粒子尺寸分布变化对差分光谱的影响,结果表明,偏振散射差分光谱能敏感地反映粒子尺寸分布的变化,在大小粒子的混合液中,大粒子浓度一定程度的增加,光谱仍保留小粒子的振荡趋势,但差分光强减小。该方法对于早期癌症检测具有潜在应用意义。