Evolutionary Algorithm-based Crystal Structure Prediction for Gold(I) Fluoride

Solid gold(I) fluoride remains as an unsynthesized and uncharacterized compound. We have performed a search for potential gold(I) fluoride crystal structures using USPEX evolutionary algorithm and dispersion-corrected hybrid density functional methods. Over 4000 AuF crystal structures have been investigated. Behavior of the AuF crystal structures under pressure was studied up to 25 GPa, and we also evaluated the thermodynamic stability of the hypothetical AuF crystal structures with respect to AuF₃, AuF₅, and Au₃F₈. Mixed-valence compound Au₃[AuF₄] with Au atoms in various formal oxidation states emerged as the thermodynamically most stable AuF species.     

Small-angle scattering from the deterministic fractal systems<Superscript>1</Superscript>

The intensity profile of small-angle neutron sc attering from three-dimensional triadic Cantor and Vicsek fractals is calculated when the fractal sets are monodisperse and their positions are uncorrelated. It is shown that the scattering intensities present minima and maxima superimposed on a power-law decay with the exponent coinciding with the fractal dimension of the scatterer. This is in accordance with the scattering from similar systems like Menger sponge or fractal jacks, which all exhibit the same behavior. For a finite iteration, the Porod power decay of the intensity is displayed at large values of momenta beyond the fractal region.     

Theoretical investigation of the adsorption and diffusion of hydrogen on the surface and in the bulk of the intermetallic compound Mg2Ni

The intermetallic compound Mg₂Ni as a potential material for hydrogen storage has been investigated theoretically. The sorption and diffusion of a hydrogen atom in the bulk and on the surface of this material, as well as the step-by-step process of dissociative chemisorption of a H₂ molecule on the surface, have been considered. The dependence of the sorption energy of atomic hydrogen on the structural characteristics of the intermetallic compound Mg₂Ni has been analyzed.     

Surfactant aggregation in solutions applied for track etching and its possible effect on the pore shape in track membranes

Surfactants are used for etching track membranes to form pores of peculiar geometries with the purpose of, e.g., producing membranes with enhanced performance. The knowledge of the state of surfactant molecules in process solutions, in particular, the regularities of their aggregation, is of importance for understanding the mechanisms of surfactant action on track etching processes. This work presents the data on sodium dodecyl( sulfophenoxy)benzene sulfonate and nonyl benzene deca(ethylene oxide) micellization in neutral and alkaline electrolyte solutions of different concentrations. The measurements are carried out using the small-angle neutron scattering. It is shown that cylindrical (ellipsoid) micelles are formed in the solutions. Characteristic sizes of micelles are determined as functions of surfactant and added electrolyte concentrations. The correlation of the data obtained with the geometry of track nanopores and the dynamics of their etching in surfactant-containing solutions is discussed.     

Reactions of iridium bis(phosphinite) pincer complexes with protic acids

Iridium pincer complexes [C₆H₃-2,6-(OPBu^t ₂)₂]Ir(H)Cl (10) and [4-EtOOCC₆H₂-2,6-(OPBu^t ₂)₂]Ir(H)Cl (11) react with protic acids undergoing metallation of one of the tert-butyl groups to form double cyclometallated products [4-R-C₆H₂-2-(OPBu^t ₂)-6-(OP(Bu^t)CMe₂CH₂)]IrCl (12, R = H; 13, R = COOEt), which are stable in air. Complex 12 reacts with CO and Bu^tNC giving the corresponding 18-electron complexes [C₆H₃-2-(OP-Bu^t ₂)-6-(OP(Bu^t)CMe₂CH₂)]Ir(L)Cl (14, L = CO; 15, L = CNBu^t). The structure of compound 14 was established by X-ray diffraction analysis.     

多功能两亲梳状聚合物的合成及包覆荧光量子点

利用溶液聚合和成酰胺反应合成了多功能梳状两亲性共聚物,聚(甲基丙烯酸-co-甲基丙烯酸十八酯)-(乙醇胺-乙二胺叶酸)(PSM-EE-FA).用红外光谱(FTIR),核磁共振(1H-NMR)及凝胶渗透色谱(GPC)表征了该聚合物的结构及分子量分布.实验结果证明合成了该聚合物,其数均分子量(Mn)为28600,多分散性为1.375.用该两亲梳状聚合物包覆油溶性CdSe/ZnS量子点,通过相转移作用,得到水溶性靶向量子点(PSM-EE-FA-QDs).该水溶性量子点溶液具有较好的稳定性.通过紫外-可见(UV-Vis)及荧光发射光谱分析对该量子点的光学性质进行研究.结果表明,PSM-EE-FA-QDs的紫外-可见光谱及荧光发射光谱峰形与原量子点基本一致.由于量子点表面聚合物层的形成,峰位发生少量红移.该量子点水溶液的荧光强度是原量子点氯仿溶液的98%,荧光产率是原量子点氯仿溶液的95%.动态光散射(DLS)及透射电镜(TEM)测试结果表明水溶性量子点分布均匀.合成的水溶性量子点不但光学性能稳定,而且聚合物及水溶性量子点的合成方法较为简便.     

X-ray scattering and volumetric <Emphasis Type="Italic">P-V-T</Emphasis> studies of the dimyristoylphosphatidylcholine-water system

The results of a study of the temperature and pressure dependence of isothermal compressibility of dimyristoylphosphatidylcholine (DMPC) are presented. The data were obtained using a small-angle X-ray scattering instrument in the Institute of Synthetic Polymer Materials (Moscow, Russia) and a device designed in the Laboratory of Neutron Physics, Joint Institute for Nuclear Research (Dubna, Russia), for studying the liquid systems by a volumetric P-V-T method. The minute baric investigation of the region of the main phase transition (transition from the gel phase into the liquid crystalline phase) was carried out. The points of the main phase transition were determined, and the phase diagram of DMPC was plotted over the pressure range of 1–800 bar at temperature from 24 to 35°C.     

Analysis of neutron spectra and fluxes obtained with cold and thermal moderators at IBR-2 reactor: Experimental and computer-modeling studies

The results of experimental and computer-modeling investigations of neutron spectra and fluxes obtained with cold and thermal moderators at the IBR-2 reactor (Joint Institute for Nuclear Research (JINR), Dubna) are presented. These studies are for the YuMO small-angle neutron scattering (SANS) spectrometer (IBR-2 beamline 4). The neutron spectra have been measured for two methane cold moderators for the standard configuration of the SANS instrument. The data from both moderators under different conditions of their operation are compared. The ratio of experimentally determined neutron fluxes of cold and thermal moderators is shown at different wavelengths. Monte Carlo simulations have been carried out to determine the spectra for cold-methane and thermal moderators. The results of calculations of the ratio of neutron fluxes of cold and thermal moderators at different wavelengths are demonstrated. In addition, the absorption of neutrons in the air gaps on the way from the moderator to the investigated sample is presented. SANS with the protein apoferritin was done with both cold methane and a thermal moderator and the data were compared. The prospects for the use of a cold moderator for a SANS spectrometer at IBR-2 are discussed. The advantages of using the YuMO spectrometer with a thermal moderator with respect to the tested cold moderator are shown.     

相对论性核碰撞中Φ介子产生和弦碎裂函数

用强子和弦级联模型LUCIAE系统研究从AGS到SPS,到RHIC,再到LHC能量核–核碰撞中Φ介子产生.采用与能量有关弦碎裂函数,并通过与荷电粒子多重数实验数据的比较确定其中的参数后,LUCIAE模型给出的Φ介子产额与实验数据也都相近,得到的事件平均弦碎裂变量随能量之增趋饱和规律,可能是核穿透性能量行为的定性表示.     

以LCD为目标的自动定焦判据选择

在光学综合自动测量中 ,使用液晶显示屏作为分划板可以大大简化结构 ,提高效率 ,真正地实现自动测量。由于液晶显示具有对比度低、噪声大等特点 ,所以根据液晶的这些特点以及图像处理和CCD信号接收的特点选择两种适用的判据进行了分析和试验比较 ,并给出了结果。结果表明 ,这两种判别函数都适用于以液晶显示屏为目标和用图像处理方法进行光学参数测量的系统 ,其中锐度判别函数更优于信息熵判别函数 ,前者具有更好的抗干扰性和稳定性 ,而且其判定结果更接近目视清晰度判别