Analytical applications of a differential technique in laser-induced fluorimetry: accurate and precise determination of uranium in concentrates and for designing microchemielectronic devices for on-line determination in processing industries

A novel instrumental technique for the direct, fast, accurate, and precise determination of uranium in concentrates and other U-rich materials (as well as to mineralized rocks) is presented. The proposed technique is an absolute methodology, based on the comparison of the fluorescence of the accurately known standard with a sample of similar but unknown concentration in the low operational range of the instrument (on same sample-dilution basis), by the use of H₃PO₄-NH₄H₂PO₄ as a fluorescence-enhancing reagent. The relative standard deviation of the proposed technique was 0.5-0.9% (n=9) at 18.1, 36.2, 61.2, and 99.6% U₃O₈. The proposed technique is suitable for the determination of uranium in samples arising from exploration projects, ores from mining operations, mill process samples, uranium ore concentrates leading to fuel fabrication as well as samples from environmental monitoring containing up to 100% uranium. The results are in good agreement with those obtained by titrimetric, gravimetric, and TBP extraction-H₂O₂ spectrophotometric methods. The precision of the technique is within the acceptable ‘pure geochemistry’ type of analysis (R.S.D. ∼ 1.0%) and is comparable even those obtained with titrimetric and gravimetric assay. The proposed differential technique coupled with flow injection may open up new advancement in instrumentation leading to design and development of microchemielectronic devices for direct on-line determination, more compatible with the tools of computer age as also to help in handling of radioactive solutions in chemical laboratories in uranium processing industries.     

葛根中葛根素的分离纯化技术进展

葛根素是葛根药材质量控制的主要指标。文章综述了近年来国内葛根提取物中葛根素的分离纯化技术进展。同时,指出β-环糊精键合固定相技术因具有绿色环保和低成本的优点,而成为发展的重点和方向。     

太阳能电池的新进展

太阳能电池的研究、开发和利用 ,倍受世界各国政府所重视。在科学前沿一系列重大发现和“新思维、新科学、新技术”的推动下 ,太阳能电池得到了迅速发展 ,它的开发和利用可为人类提供清洁 (绿色 )的能源 ,对促进人类社会的文明与进步具有重要的意义。     

近两年国内气相色谱的进展

对近两年国内学者对气相色谱(GC)的研究和应用进行了综述.GC已经是一门十分成熟和广泛应用的分析技术,近两年国内学者的研究发展近似于国外的GC研究和发展,基础性GC研究不多,大多为GC在各个领域的应用研究.应用研究包括在食品、中药、水、气、石油、石化、工业品、农残和烟草分析中的应用.     

纳米SiO2的表面处理及其在聚合物基纳米复合材料中的应用进展

简要介绍了纳米二氧化硅(SiO2)粒子的制备方法、结构和特性,对近年来国内外纳米SiO2的表面处理方法及聚合物/SiO2纳米复合材料的制备方法进行了阐述,并针对不同改性方法和制备方法的特点加以分析比较;讨论了SiO2粒子的分散机理和增强机理,并对未来的研究内容及方向提出展望。     

广义连续统场论的现状和展望

对广义连续统场论的发展过程加以回顾,对其发展现状加以综述,并对包括其目标、非线性理论、多场问题、计算机化趋势、物理参数和应用等今后的研究方向提出了若干建议．      

高分子手性固定相的研究进展

手性药物的应用对人类健康产生了深远影响。随着化学、材料、生命等学科的发展,人们对手性药物分离分析的研究日趋深入。色谱法在手性药物分离分析中得到了广泛应用,手性固定相的选择是实现手性色谱拆分的关键。以高分子材料作为手性固定相并对其进行衍生以优化手性分离性能是近些年的研究热点。本文介绍了近几年高分子手性固定相在手性分离中的研究进展,并对其发展前景进行了展望。     

A review of research progress in air-to-water sound transmission

International and domestic research progress in theory and experiment and applications of the air-to-water sound transmission are presented in this paper. Four classical numerical methods of calculating the underwater sound field generated by an airborne source, i.e., the ray theory, the wave solution, the normal-mode theory and the wavenumber integration approach, are introduced. Effects of two special conditions, i.e., the moving airborne source or medium and the rough air-water interface, on the air-to-water sound transmission are reviewed. In experimental studies, the depth and range distributions of the underwater sound field created by different kinds of airborne sources in near-field and far-field, the longitudinal horizontal correlation of underwater sound field and application methods for inverse problems are reviewed.