Luminescence quantum yield determination for molecules adsorbed onto solid powdered particles.

A new methodology for the determination of the fluorescence quantum yield of dyes adsorbed onto microcrystalline cellulose is presented and applied to rhodamine 101, cresyl violet and auramine O. It is based on a previously reported method by Ruetten and Thomas (J. Phys. Chem., 1998, 102, 598-606), which is not applicable to the dyes used in the present study. It uses ground-state diffuse reflectance spectra obtained with and without filters, which prevents the luminescence of the dye from reaching the integrating sphere and the photodetector. New equations are presented here, correcting for the fluorescence emission of the dye, which depends on the detector sensitivity. Cut-on filters, which have a transmittance close to unity in the absorption region, and close to zero in the emission region, of the dye are used to obtain corrected reflectance spectra. The influence of the substrate was also taken into account. This methodology may be applied to other probes and surfaces or emissions of a different nature (i.e., phosphorescence or delayed fluorescence), and constitutes a very simple and general procedure to solve the important problem of luminescence quantum yield determination of probes adsorbed onto solid powdered surfaces.     

Orthogonality Preserving Transformations on Indefinite Inner Product Spaces: Generalization of Uhlhorn's Version of Wigner's Theorem

We present an analogue of Uhlhorn's version of Wigner's theorem on symmetry transformations for the case of indefinite inner product spaces. This significantly generalizes a result of Van den Broek. The proof is based on our main theorem, which describes the form of all bijective transformations on the set of all rank-one idempotents of a Banach space which preserve zero products in both directions.     

Density functional calculations for shell closures in Mg clusters

Motivated by recent measurements on Mg clusters we discuss the electronic structure and shell closures of these type of systems in the framework of self-consistent mean fields derived from density-functional theory. The ionic background is treated at different levels of refinement: spherical jellium model, and the spherically-averaged-pseudo-potential scheme (SAPS) with local as well as non-local pseudo-potentials. The ionic positions in SAPS are optimized using a Metropolis simulated annealing. It is shown that the details of ionic background influence sensitively the electronic levels sequence near the Fermi energy. In particular, the non-local effects from the pseudo-potential change the relations between states with high and with low angular momentum. Some of these effects go into the right direction towards experiment. Received 3 July 2001 and Received in final form 29 October 2001     

差分方程解对初值连续性问题

本文讨论了差分方程的解对初值的连续性问题，对较一般的方程给出了保证解对初值连续的充分条件，对线性方程（组）利用系数矩阵的特征值给出其解对初值连续的条件．     

SOME GEOMETRIC PROPERTIES OF BROWNIAN MOTION ON SIERPINSKI GASKET

Let {X(t),t≥0} be Brownian motion on Sierpinski gasket,The Hausdorff and packing dimensions of the image of a ompact set are studied,The uniform Hausdorff and packing dimensions of the inverse image are also discussed.     

HIRFL新的束流分配系统

随着CSR的建成和兰州重粒子加速系统(HIRFL)实现质子加速,HIRFL现有的束流传输系统已不能满足越来越多的物理实验对供束时间的要求,为此,对原有的HIRFL的束流输运系统进行了分时供束改造,新的束流分配系统可以在给CSR供束和不供束两种情况下,同时使用SFC和SSC的束流在多个实验终端进行物理实验,介绍了新设计的HIRFL束流分配系统的布局和束流光学计算结果.     

Synthesis and structure of grafted layer of silicas modified with alkanesulfonic acid

A convenient method for preparation of silicas modified with alkanesulfonic acid through the reaction of NaHSO₃ with the C₂H₃ groups grafted on the SiO₂ surface was proposed. The influence of the carrier and the structure of the grafted layer on the modification process was studied by DRIFT, MAS NMR, and temperature-programmed desorption mass spectrometry (TPD-MS). It was found that at most 40% of the C₂H₃ groups transform to the acid sites, which mostly have the structure of 2-Si-ethanesulfonic acid. The mechanism of the thermal decomposition of the grafted groups, which are stable up to 240 °C, was proposed. The monomeric structure of the grafted layer leads to partial olygomerization of the C₂H₃ groups through the N=N bonds.     

Modified Moment Problem in Complex Domains

We study the moment problem in a complex domain. The results obtained generalize and sharpen the well-known Kaz'min result. We also consider applications of these results to the Abel--Goncharov problem (the uniqueness and construction problem) and to the completeness problem for systems of analytic functions.     

一个半正Sturm-Liouville边值问题的n个解的存在性

通过构造与非线性项有关的辅助函数并考察这个辅助函数在有界集上的性质，对于Sturm-Liouville边值问题建立了几个解的存在性，其中非线性项是下有界的．同时，给出了正解和非平凡解的一个判别方法．主要工具是锥压缩与锥拉伸型的Krasnosel’skii不动点定理．     

Banach空间中渐近非扩张型映象的Ishikawa迭代序列的收敛问题

文章研究了Banach空间中渐近非扩张型映象的具误差的修正Ishikawa迭代序列的收敛问题，所得结果改进和发展了文献[1-6]的相关结果。