Fluorescence Enhancement of Aflatoxins Using Native and Substituted Cyclodextrins

Cyclodextrins have been used as fluorescence enhancers in HPLC to improve thedetection limits of aflatoxins, cancerogens which can be found in severalfoodstuffs. In this work, a screening of several cyclodextrins has been performedin order to find the factors affecting the fluorescence enhancement. Evidence for formationof a 1 : 1 AF-CD inclusion complex has been achieved by titration and competitiveexperiments with adamantanecarboxylic acid and by fluorescence quenching by KI.Stability constants of the AF-CD complexes were evaluated.     

Fast heating in µ-thermal analysis</o:p>

Summary Thermal analysis of the 10 μm surface of materials using TA Instruments' μ-TA thermal probe and pulsed force mode AFM has shown promising results. This addresses the need of additional surface characterization based on principle of Thermal Analysis, which is complementary to other surface characterization techniques, i.e., Surface-IR, TOF-SIMS, etc. The method calls for identification of surface landscape by imaging first, followed by fast heating the spots of interest. The micro thermal probe is viewed to heat a small material with a tiny heater rather than to heat small material with a large heater in conventional thermal analysis. In this paper, we demonstrate the applicability in the adhesion temperature of the topical coatings of Tyvek? HDPE sheets, fusion of the heat-processed polyethylene fibers in a bundle, the surface crystallinity of PET pellets, and two examples of phase images of toughened Nylon 66. Comparisons were made where it is possible with standard thermal analysis techniques as well as with the microscopic techniques of AFM, TEM and optical.     

VISCOUS FORCES BETWEEN TWO SPHERES COLLIDING THROUGH INTERSTITIAL POWER-LAW FLUID

Interaction between two spheres with an interstitial fluid is essential in Discrete Element modeling for simulating the behaviors of ‘wet‘ particulate materials. In this paper the interaction between two spheres with an interstitial Power-law fluid was approximately resolved as normal and tangential interactive models respectively, for which the governing equations were simplified on the basis of Reynolds approximation. These equations were then solved analytically together with the boundary conditions to obtain the pressure distributions for each individual model, and event ually solutions of the viscous squeeze force and the tangential viscous resistance were obtained, which provide a set of solutions for implementing into DEM code or other purposes.     

Strain effects on optical properties of pyramidal InAs/GaAs quantum dots

Strain distribution and optical properties in a self-assembled pyramidal InAs/GaAs quantum dot grown by epitaxy are investigated. A model, based on the theory of linear elasticity, is developed to analyze three-dimensional induced strain field. In the model, the capping material in the heterostructure is omitted during the strain analysis to take into account the sequence of the fabrication process. The mismatch of lattice constants is the driving source of the induced strain and is treated as initial strain in the analysis. Once the strain analysis is completed, the capping material is added back to the heterostructure for electronic band calculation. The strain-induced potential is incorporated into the three-dimensional steady-state Schrödinger equation with the aid of Pikus–Bir Hamiltonian with modified Luttinger–Kohn formalism for the electronic band structure calculation. The strain field, the energy levels and wave functions are found numerically by using of a finite element package FEMLAB. The energy levels as well as the wave functions of both conduction and valence bands of quantum dot are calculated. Finally, the transition energy of ground state is also computed. Numerical results reveal that not only the strain field but also all other optical properties from current model show significant difference from the counterparts of the conventional model.     

温差电现象的进一步讨论

一般认为温差电动势与温差及导体的材料有关，与温度梯度无关。本文通过实验和理论两个方面证明了温差电动势与温度梯度也有关系。     

储存环内电子冷却过程模拟

考虑储存环内离子的横向振荡和纵向振荡的运动特性,模拟了HIRFL-CSR内重离子束的电子冷却过程.给出了离子束的横向发射度和纵向动量散度随时间连续变化的图象,由此分析了电子束的空间电荷效应,冷却段色散函数和横向电子束温度对冷却过程快慢的影响.     

A Uniqueness Result for a Model for Mixtures in the Absence of External Forces and Interaction Momentum

We consider a continuum model describing steady flows of a miscible mixture of two fluids. The densities ϱ _i of the fluids and their velocity fields u ⁽ⁱ⁾ are prescribed at infinity: ϱ _i |_∞ = ϱ _i∞ > 0, u ⁽ⁱ⁾|∞ = 0. Neglecting the convective terms, we have proved earlier that weak solutions to such a reduced system exist. Here we establish a uniqueness type result: in the absence of the external forces and interaction terms, there is only one such solution, namely ϱ _i ≡ ϱ _i∞, u ⁽ⁱ⁾ ≡ 0, i = 1, 2. This work was supported by the SFB 611 at the University of Bonn and the European HYKE network (contract no. HPRN-CT-2002-00282). The third author was also supported by the project CSF 201/03/0934, and by MSM 0021620839.     

Classification of metal ions according to their complexing properties: a data-driven approach

Factor, cluster and self-organizing map analyses were performed for the stability constants of complexes of 24 metal ions and hydrogen with 3960 ligands (15606 values of log K₁). Five factors reproduce 89% of data variability. Both direct clusterization and clusterization on the basis of factor analysis established the existence of six different classes of similar cations. The similarity series for metal ions and relative similarity of several ions are discussed and the Kohonen two-dimensional map, which visually represents the similarity, is presented.     

On the Order of the Lebesgue Constants for Interpolation by Algebraic Polynomials from Values at Uniform Nodes of a Simplex

For interpolation processes by algebraic polynomials of degree n from values at uniform nodes of an m-simplex, where m ≥ 2, we obtain the order of growth in n of the Lebesgue constants, which coincides with that in the one-dimensional case for which Turetskii obtained an asymptotics earlier.__________Translated from Matematicheskie Zametki, vol. 77, no. 6, 2005, pp. 814–831.Original Russian Text Copyright ©2005 by N. V. Baidakova.     

用力敏传感器测量液体表面张力系数

从力敏传感器测力的原理出发，总结了用力敏传感器测量液体表面张力系数实验的诸多优点，并阐述了这个实验的现实意义．