Influence of spatial coherence on scattering by a particle

We analyze the effect of partial spatial coherence on the scattering of light by an arbitrary particle. We extend the definition of the extinction cross section to spatially partially coherent fields. We then discuss the effect of the partial coherence on the extinction scattering cross section by introducing the Wigner transform. It is shown that for rotationally invariant scatterers, the extinction cross section does not depend on the coherence of the incident field. The effect of partial coherence on the angular behavior of the scattered intensity is also discussed in the framework of the Wigner transform. The implications for practical applications are considered.     

Tamoxifen derivatives for delivery of the antitumoral (DACH)Pt group: selective synthesis by McMurry coupling,and biochemical behaviour

The goal of our study was to potentiate the effects of the ((R,R)-trans-1,2-diaminocyclohexane)-platinum(II) fragment [(DACH)Pt], known for its cytotoxic properties, either with tamoxifen (Tam), the most widely used antiestrogen in the treatment of hormone-dependent breast cancers, or with its active metabolite hydroxytamoxifen (hydroxy-Tam). We coupled Tam or hydroxy-Tam derivatives bearing a malonato group at the para position of the beta aromatic ring with the (DACH)Pt fragment. The malonato-Tam and malonato-hydroxy-Tam compounds were prepared through McMurry coupling of the appropriate ketones. The presence of the malonate group resulted in a pronounced stereospecificity in the reaction, since malonato-Tam was obtained only as the Z isomer, while malonato-hydroxy-Tam was obtained as an 80/20 E/Z mixture. Attribution of the isomeric structures was achieved by 2D NMR spectroscopy. The platinum complexes (DACH)Pt-malonato-Tam and (DACH)Pt-malonato-hydroxy-Tam were then prepared by coupling the barium salts derived from the malonato-Tam and malonato-hydroxy-Tam with the nitrate derived from (DACH)PtCl(2). Study of the biochemical properties of these two platinum complexes showed that, while the hydroxy-Tam complex is satisfactorily recognized by the estrogen receptor (relative binding affinity, RBA=6.4 %), the Tam complex is less well recognized (RBA=0.5 %). The effects of these complexes on two hormone-dependent breast cancer cell lines (MCF7 and MVLN) were studied in vitro. Both complexes showed an antiproliferative effect on MCF7 cells, and an antiestrogenic effect on MVLN cells. The observed effects appear to be essentially antihormonal, since incorporation of the (DACH)Pt fragment into the tamoxifen skeleton did not cause an increase in the cytotoxicity of the complexes.     

Addition patterns, codes and contact graphs for fullerene derivatives

The mathematical concept of the d-code and its associated contact graph give a model for sterically constrained addition patterns in fullerene derivatives C60Xm and C70Xm. In combination with simple electronic arguments, the stoichiometries, symmetries, and location of addends can be predicted, yielding a small number of candidates for further study. For example, sterically and optimal solutions C60Xm with pairwise separation of d bonds between addends are found at m(d) = 24(2), 12(3), 6(4,5), 2(6 to 9). The solution for C60X24 is unique, and the model selects 12 candidates for C60X12 from a starting set of 11661527060 possibilities.     

Modeling of ultrasonic wave propagation in teeth using PSpice: a comparison with finite element models

Ultrasound is used extensively in the medical field for the detection and characterization of a variety of features in the human body. Finite element models used to understand ultrasonic wave propagation in teeth have been developed so that ultrasound techniques could be realized in dentistry. This paper presents a hypothesis that underlies one possible design of an ultrasonic tool that can be used in a clinical environment, as well as several models that describe acoustic field simulation, propagation, and interaction with the layers of several tooth structures. A complete PSpice model of a single-element transducer based on Redwood's version of Mason's equivalent circuit, a focusing lens, and a multi-layer tooth structure is used to illustrate the validity of this hypothesis. Transmission line theory is employed as a basis for the models of the piezoceramic, the lens, and the different tooth layers. Results clearly depict the transmission and reflection of the ultrasonic waves as they travel through the layers within the tooth structure and point out the noticeable similarity to longitudinal L-wave signatures produced by axisymmetric finite element models presented in earlier studies.     

Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) and wheat straw fibre composites: thermal, mechanical properties and biodegradation behaviour

The thermal and mechanical behaviour of a biotechnological polyester (poly(3-hydroxybutyrate-co-hydroxyvalerate) (PHBV) reinforced with wheat straw fibres has been investigated. In order to improve chemico-physical interactions between the components, the reinforcing agent has been previously submitted to a treatment with high temperature steam leading to fibres richer in cellulose and more reactive. The addition of straw fibres has been found to increase the rate of PHBV crystallisation, while it does not affect the crystallinity content. Furthermore, the comparison of the mechanical properties has shown that the composites exhibit higher Young moduli and lower values of both the stress (_B) and strain (_B) to break than the neat matrix of PHBV. The biodegradability in different environments by means of short and long term tests has been studied. It has been observed that the presence of straw does not affect biodegradation rate evaluated in liquid environment and in long term soil burial tests. In the composting simulation test the rate of biodegradation is reduced for composites with more than 10% of straw content. The morphology of the composites has also been investigated and correlated to the biodegradation process.     

基于Agent技术的在线测试系统研究与设计

为了使数字教育服务提高到一个新的水平，把Agent技术引入到网络教学中，可以更好地实现网络教学信息系统的自动化和智能化。近年来，许多科研人员纷纷投入到Agent技术的研究中。采用面向Agent软件开发方法，结合Agent技术的优越性，提出了一个网络教学中基于Agent技术的在线测试系统设计模型．在一定程度上满足了教师和学生等对在线测试系统动态性和智能性需求。     

Asymptotic Stability of a Rate Control System With Communication Delays

We study the issue of asymptotic stability of a family of rate control algorithms with communication delays between network elements and extend our earlier results: First, we derive delay-dependent stability conditions with a family of well-known utility and resource price functions when a finite upper bound is known on the feedback delay. These conditions are shown to be consistent with known stability conditions in two extreme cases-no delay or an arbitrarily large delay. Secondly, we provide a lower bound on the convergence rate with the same utility and resource price functions when delay-independent stability conditions hold.     

Polychaete-Like Undulatory Robotic Locomotion in Unstructured Substrates

A biological paradigm of versatile locomotion and effective motion control is provided by the polychaete annelid worms, whose motion adapts to a large variety of unstructured environmental conditions (sand, mud, sediment, water, etc.), and could thus be of interest to replicate by robotic analogs. Their locomotion is characterized by the combination of a unique form of tail-to-head body undulations (opposite to snakes and eels), with the rowing-like action of numerous lateral appendages distributed along their long segmented body. Focusing on the former aspect of polychaete locomotion, computational models of crawling and swimming by such tail-to-head body undulations have been developed in this paper. These are based on the Lagrangian dynamics of the system and on resistive models of its interaction with the environment, and are used for simulation studies demonstrating the generation of undulatory gaits. Several biomimetic robotic prototypes have been developed, whose undulatory actuation achieves propulsion on sand and other granular unstructured environments. Extensive experimental studies demonstrate the feasibility of robot propulsion by tail-to-head body undulations in such environments, as well as the agreement of its qualitative and quantitative characteristics to the predictions of the corresponding computational models.     

薄膜X射线测厚仪的研制

介绍了用于薄膜测厚的全自动往复式X射线测厚仪的研制,详述了该测厚仪的硬件组成和测厚的工作原理.该装置已成功运行在双向拉伸聚丙烯(BOPP)薄膜生产线上.     

In-Plane Coupling of Light From InP-Based Photonic Crystal Band-Edge Lasers Into Single-Mode Waveguides

In this paper, we analyze the coupling of light from photonic-crystal band-edge lasers into single-mode waveguides. Both active and passive devices lie in the same plane and coupling of light is achieved by using parabolic and nanotapers in InP based epitaxial structures. Two- and three-dimensional finite-difference time-domain methods are employed to analyze these devices. Coupling efficiencies higher than 80% can be obtained with parabolic couplers. We also present laser configurations that can reduce multiwavelength coupling of light into single-mode waveguides, using structures that are similar to coupled cavity Fabry-Peacuterot lasers