X射线荧光分析钒钛铁矿中主次量元素

四硼酸锂为熔剂 ,硝酸锂为氧化剂防止硫元素挥发损失 ,溴化锂作脱模剂 ,玻璃熔片法制备样品。干扰曲线法结合理论α系数法对谱线重叠干扰和基体效应进行校正 ,建立了 XRF测定钒钛铁矿中 Mg,Al,Si,P,S,Ca,Ti,V,Mn,TFe等主次量元素的分析方法。该方法经标准样品验证 ,与推荐值符合较好。 10次制样测量各组分 RSD在 0 .2 7%— 5 .2 4 %范围内     

微纳相控线阵超声换能器参数的理论分析*

微纳相控线阵超声换能器参数(阵元数目、阵元宽度及阵元间距)直接影响其横向声场分布,而其横向声场分布是能否实现高成像分辨率、大探测深度的决定性因素,也是制备换能器的主要依据。该文利用数值模拟研究微纳相控线阵超声换能器阵元参数对其横向声场中主瓣强度、-3 dB主瓣宽度、第一级旁瓣及栅瓣的影响。结果表明,主瓣强度随着阵元数目增加而增大,随阵元间距减小而增大,随着阵元宽度的增大呈现先增大后减小的趋势;-3 dB主瓣宽度随着阵元数目和阵元间距的增大而减小,随着阵元宽度的减小而减小;此外,减小阵元数目、减小阵元间距或增大阵元宽度均可以抑制旁瓣;栅瓣在阵元间距满足一定条件时可以完全消除。通过这些研究为微纳相控线阵超声换能器的优化设计与制备提供理论参考。     

后向散射式路道能见度激光测量仪的研究

后向散射式跑道能见度激光测量仪主要由光学发射与接收系统、信号放大与处理系统及显示系统三部分组成。其中,光学发射与接收系统主要包括：Ｎｄ ：ＹＡＧ 激光器、倍频器、准直镜、扩束镜、光学接收镜头、截止滤光片、窄带干涉滤光片及光电转换系统等;信号放大与处理系统主要包括：小信号放大电路、延时电路、采样保持电路、多路模拟开关、模 数转换电路及８０３１ 单片机等;显示系统主要由数字显示器、打印机及接口电路等组成。介绍了该测量仪的工作原理、基本结构和主要技术指标,讨论了其中的技术难点及其相应的解决方法。     

波导短程透镜的优化理论设计研究

本文给出了非球面短程透镜的优化理论设计。卷边与平面波导连接处的曲率半径为无限大,卷边与实际透镜连接处的曲率半径为较大的有限值。完善了短程透镜的一般解析法。     

表面电化学和电化学催化研究进展——97'国际电化学联合大会和97'国际表面电化学会议综述

表面电化学和电化学催化研究进展①——９７＇国际电化学联合大会和９７＇国际表面电化学会议综述孙世刚（厦门大学化学系,固体表面物理化学国家重点实验室厦门３６１００５）表面电化学和电化学催化是当前极为活跃的研究领域．这首先得益于近年来各种物理和光谱技术的飞...     

Synthesis,in-silico antiviral screening and in-vitro antibacterial screening of a novel chalcone derivatives

A new series of novel chalcones was synthesized and subjected to screening of theoretical molecular and biological properties. For evaluating the theoretical molecular properties of these molecules Molinspiration and Osiris software were used. It was concluded from data that the majority of molecules exhibited theoretical molecular and biological properties similar to that of standard drugs. Role of Hemagglutinin is vital during the attack of virus on cells so Hemagglutinin inhibitors may act as potent antiviral agents. Considering this fact in-silico studies were performed using the SwissDock screening engine on Hemagglutinin target PDB code 1HGH. Hemagglutinin inhibition potential in terms of binding affinity was expressed as ΔG values ranging from −8.71 kcal/mol to −7.39 kcal/mol. Compound IIIm showed maximum binding affinity with ΔG value −8.71 kcal/mol followed by compound IIIj ΔG value −8.31 kcal/mol. It's prudent from ΔG values that compounds may act as potent antiviral agents. Compounds were also screened for in-vitro antibacterial activity against five pathogenic strains. Most of the compounds exhibited low to moderate activity against strains under study. Compound IIIn demonstrated good activity against four pathogenic strains with highest zone of inhibition of 16 mm against K. pneumoniae and S. typhi.     

A dual-functional chemosensor based on acylhydrazone derivative for rapid detection of Zn(II) and Mg(II): Spectral properties,recognition mechanism and application studies

In this work, an acylhydrazone derivative (QN62) was developed via the one-step condensation of 6-hydroxy-2-naphthoic hydrazide with quinoline-8-carboxaldehyde. The structure of the QN62 compound was characterized by ¹H NMR, ¹³C NMR, HR-MS (ESI), and X-ray crystallography. As a dual-functional turn-on fluorescence chemosensor, QN62 exhibited rapid recognition for Zn²⁺ in DMSO-H₂O (4:1, v/v) and Mg²⁺ in ethanol-H₂O (9:1, v/v). The enhancement in fluorescence detection was associated with the coordination reaction between QN62 and the target ions, which promoted intramolecular charge transfer and prevented the CN isomerization process. Simultaneously, a rapid color change from colorless to yellowish-green or yellow under UV light (365 nm) was easily visible to the naked eye. Under optimal conditions, the limit of detection and limit of quantification were 32.3 nM and 97.8 nM for Zn²⁺ and 16.1 nM and 48.9 nM for Mg²⁺, respectively. The recognition mechanism was reasonably speculated based on analysis of the Job’s plot, HR-MS, ¹H NMR, and density functional theoretical calculations. Utilizing silica-gel plates fabricated from the QN62 chemosensor, the visual and rapid identification of Zn²⁺ and Mg²⁺ was successfully achieved, which could provide a convenient approach for on-site detection in environmental fields. The QN62 chemosensor could also quantify trace amounts of Zn²⁺ and Mg²⁺ in water samples. Furthermore, the cell imaging experiments indicated that QN62 could effectively sense intracellular Zn²⁺ and Mg²⁺, providing potential applications in biological systems.     

Nucleotide Recognition by a Guanidinocalixarene Receptor in Aqueous Solution

Nucleotides participate in various physiological processes through their supramolecular interactions with biomolecules. Therefore, the molecular recognition of nucleotides became an important topic in supramolecular chemistry and exhibited many biomedical applications. Guanidinocalixarenes showed very strong binding affinities towards nucleotides, even reaching the nanomolar level. In this work, we systematically determined the binding constants between a typical guanidinocalixarene(guanidinium-modified calix[5]arene, GC5A) and various nucleotides and revealed the driving forces behind the molecular recognition using theoretical calculations. The electrostatic interactions and hydrogen bonding provided by the phosphate groups of the nucleotides dominated the binding between the nucleotides and GC5A. The lower rim alkyl chains and the skeleton of GC5A provide preorganized cavity and upper guanidinium groups. The difference in the type of nucleobase is also attributed to the different binding affinities. This work provides insight into the molecular recognition of nucleotides and facilitates the development of new supramolecular hosts for nucleotides and related biological applications.