便携式多源光谱融合水质分析仪的研制

采用光谱信息融合理论,研制了一种新型便携式多参数水质分析仪,自行设计了仪器的分析方法、硬件结构、内部工作原理及软件功能.可作为一种无须化学试剂、体积小、快速、易于野外现场作业的绿色水质检测工具.通过对少量水质样品的光谱测量分析,快速检测了总有机碳(TOC)、化学需氧最(COD)等6类水质有机污染物指标.实际测量结果表明,本仪器采用的基于多源光谱信息融合的水质分析方法测量精度显著优于目前市场上普遍采用的常规紫外吸收光谱法.     

多功能抗激光损伤高反射膜

为了能同时满足半导体激光器和YAG激光器对薄膜的特殊要求,在分析高反射膜理论的基础上,选取TiO2和SiO2为高、低折射率材料镀制了周期性多层介质高反射膜。研究了材料的光学及机械特性,重点解决了薄膜的消偏振和抗激光损伤问题。实验采用电子束真空镀膜并加以考夫曼离子源辅助沉积,利用TFC软件进行膜系设计,通过调整镀膜工艺参数和监控方法,在10mm×1．8mm的K9基底上镀制了符合要求的高反射膜,结果表明,当激光以45°入射时,薄膜在900～1100nm的P光与s光的反射率均大于99．95％。所制备的高反射膜性能稳定,抗激光损伤阈值高,能同时满足两种激光器的使用要求。     

石墨烯低温热膨胀和声子弛豫时间随温度的变化规律

考虑到原子非简谐振动和电子-声子相互作用,用固体物理理论和方法研究了石墨烯格林艾森参量和低温热膨胀系数以及声子弛豫时间随温度的变化规律,探讨了原子非简谐振动项对它们的影响.结果表明:1)在低于室温的温度范围内,石墨烯的热膨胀系数为负值,随着温度的升高,其热膨胀系数的绝对值单调增加,室温热膨胀系数为-3.64×10~(-6)K~(-1);2)简谐近似下的格林艾森参量为零.考虑到非简谐项后,格林艾森参量在1.40-1.42之间并随温度升高而缓慢增大,几乎成线性关系,第二非简谐项对格林艾森参量的影响小于第一非简谐项;3)石墨烯声子弛豫时间随着温度的升高而减小,其中,温度很低(T10 K)时变化很快,此后变化很慢,当温度不太低(T300 K)时,声子弛豫时间与温度几乎成反比关系.     

Coupled caloric effects in multiferroics

We propose a conception – coupled caloric effect   where the enhanced caloric effects originate from the coupling among magnetic, ferroelectric, and structural degrees of freedom. Specifically, as the magneto-electric case, the magnitude of the coupled caloric effect was evaluated for a ferromagnetic–ferroelectric system using a phenomenological calculation based on Landau phase transition theory. The isothermal entropy change is greatly enhanced by increasing the magneto-electric coupling strength. This work indicates that the caloric effect in a ferromagnetic–ferroelectric coupled system consists of pure magnetic entropy change (Δ_SM$\mathrm{\Delta }{S}_M$), pure ferroelectric one (Δ_SE$\mathrm{\Delta }{S}_E$), and coupled one (Δ_SME$\mathrm{\Delta }{S}_{\mathit{ME}}$) that plays a significant part. The counterpart of the last one in magneto-structural coupled system was usually neglected. Our study provides a route to energy-efficient refrigeration via realization of coupling among various ferroic orders.     

Origin of Fluorescence Lifetimes in Human Serum Albumin. Studies on Native and Denatured Protein

Human serum albumin consists of a single polypeptide of 585 amino acid residues with 1 Trp residue. In the present work, we measured fluorescence lifetimes of the protein in both native and denatured states. The results indicate that Trp emission occurs with three lifetimes in both states. Lifetimes values and contribution to the global emission decay differ between the two states. Data are interpreted as the results of an emission occurring from three substructures of the tryptophan formed in the excited state. Two of these substructures are already present for the tryptophan free in solution. The third lifetime is the result of the interaction between the tryptophan residue and surrounding microenvironment. The populations of these substructures characterized by the pre-exponential parameters of the fluorescence lifetimes are dependent on the fluorophore microenvironment and on the global protein structure.     

Synergistic effect of silver seeds and organic modifiers on the morphology evolution mechanism of silver nanoparticles

Triangular, truncated triangular, quadrangular, hexagonal, and net-structured silver nanoplates as well as decahedral silver nanoparticles were manipulatively prepared starting from silver nitrate and silver seeds in the presence of poly(ethylene glycol) (PEG), poly(N-vinyl pyrrolidone) (PVP), and Tween 80 at room temperature, respectively. UV-vis spectroscopy, XRD, HRTEM, SAED, and FTIR were used to illustrate the crystal growth process and to characterize the resultant silver nanoparticles. It was found that the silver seeds and organic modifiers synergistically affected the morphology evolution of the silver nanoparticles. The co-presence of silver seeds and PEG was beneficial to the formation of triangular and truncated triangular silver nanoplates; the silver seeds and PVP favored the formation of polygonal silver nanoplates; the silver seeds and Tween 80 preferred to the formation of net-structured silver plates. The morphology evolution of the resultant silver nanoparticles was correlated with the crystallinity of the silver seeds and the adsorption ability of the organic modifiers on the crystal surfaces.     

Detection of source inhomogeneity through event-by-event two-pion Bose–Einstein correlations

We develop a method for detecting the inhomogeneity of the pion-emitting sources produced in ultra-relativistic heavy ion collisions, through event-by-event two-pion Bose–Einstein correlations. The root-mean-square of the error-inverse-weighted fluctuations between the two-pion correlation functions of single and mixed events are useful observables for the detection. By investigating the root-mean-square of the weighted fluctuations for different impact parameter regions people may hopefully determine the inhomogeneity of the particle-emitting in the coming Large Hadron Collider (LHC) heavy ion experiments.     

Properties of proton-rich nuclei in a three-body model

Using a three-body model and realistic two-body potentials, we investigate the properties of the nuclei ¹⁸Ne and ²⁸S near the proton dripline. We figure out the two-proton separation energies, occupation of the valence protons, root-mean-square radii of matter and the valence protons. Besides, the spatial correlation densities are displayed to reflect the correlation between the two valence protons. The first excited 0⁺ state of ¹⁸Ne is most likely to be a halo state according to our calculation. Turning off the Coulomb interactions among the three-body systems, we get the two-neutron separation energies and configuration of the valence neutrons of their corresponding mirror nuclei. The results indicate that the three-body model is proper to describe some proton-rich nuclei and can be used to deduce reliable information.     

光栅常数的简便测量方法

本文给出光栅常数两种简便测量方法。