随机库存分配问题的一种求解方法

讨论了在VMI管理思想下对具有随机需求特性的多客户库存分配问题 ,重点论述了有效近似算法的设计过程 ,最后基于一组模拟数据给出了一个算例。     

A New Hand-Held Microsystem Architecture for Biological Analysis

This paper presents a hand-held microsystem based on new fully integrated magnetoresistive biochips for biomolecular recognition (DNA hybridization, antibody antigen interaction, etc.). Magnetoresistive chip surfaces are chemically treated, enabling the immobilization of probe biomolecules such as DNA or antibodies. Fluid handling is also integrated in the biochip. The proposed microsystem not only integrates the biochip, which is an array of 16times16 magnetoresistive sensors, but it also provides all the electronic circuitry for addressing and reading out each transducer. The proposed architecture and circuits were specifically designed for achieving a compact, programmable and portable microsystem. The microsystem also integrates a hand-held analyzer connected through a wireless channel. A prototype of the system was already developed and detection of magnetic nanoparticles was obtained. This indicates that the system may be used for magnetic label based bioassays     

Alumina-supported catalysts for propane oxidative dehydrogenation from mixed VXM(6−X)O19 (M=W, Mo) hexametalate precursors

γ-Al₂O₃ supported vanadium oxides were modified by tungsten and molybdenum oxides in order to improve dispersion and selectivity towards olefins in propane oxidative dehydrogenation (ODH). Both vanadium–tungsten and vanadium–molybdenum catalysts were obtained by adsorption of mixed isopolyanions (VW₅O₁₉⁵⁻, V₂W₄O₁₉⁴⁻, VMo₅O₁₉⁵⁻ and V₂Mo₄O₁₉⁴⁻) from aqueous solutions. The isopolyanion solutions were characterized by UV-Vis and ⁵¹V NMR spectroscopy. Vanadium, vanadium–tungsten and vanadium–molybdenum precursors and catalysts were also characterized by UV-Vis (diffuse reflectance) and solid state ⁵¹V NMR spectroscopy. An improved selectivity to propene in the presence of tungsten and molybdenum in VO_x/γ-Al₂O₃ was observed and attributed to dilution of vanadium by tungsten or molybdenum oxides on the γ-Al₂O₃ surface.     

分布式光纤拉曼放大器的增益平坦设计

介绍了在波分复用（WDM）系统中分布式光纤拉曼放大器（FRA）的理论分析模型。在此基础上，对增益平坦设计所需考虑的因素进行了分析；最后通过试验证明了它的有效性。     

Clinical chemistry of common apolipoprotein E isoforms

Apolipoprotein E plays a central role in clearance of lipoprotein remnants by serving as a ligand for low-density lipoprotein and apolipoprotein E receptors. Three common alleles (apolipoprotein E(2), E(3) and E(4)) give rise to six phenotypes. Apolipoprotein E(3) is the ancestral form. Common apolipoprotein E isoforms derive from nucleotide substitutions in codons 112 and 158. Resulting cysteine-arginine substitutions cause differences in: affinities for low-density lipoprotein and apolipoprotein E receptors, low-density lipoprotein receptor activities, distribution of apolipoprotein E among lipoproteins, low-density lipoprotein formation rate, and cholesterol absorption. Accompanying changes in triglycerides, cholesterol and low-density lipoprotein may promote atherosclerosis development. Over 90% of patients with familial dysbetalipoproteinaemia have apolipoprotein E(2)/E(2). Apolipoprotein E(4) may promote atherosclerosis by its low-density lipoprotein raising effect. Establishment of apolipoprotein E isoforms may be important for patients with diabetes mellitus and several non-atherosclerotic diseases. Apolipoprotein E phenotyping exploits differences in isoelectric points. Isoelectric focusing uses gels that contain pH 4-7 ampholytes and urea. Serum is directly applied, or prepurified by delipidation, lipoprotein precipitation or dialysation. Isoelectric focusing is followed by immunofixation/protein staining. Another approach is electro- or diffusion blotting, followed by protein staining or immunological detection with anti-apolipoprotein E antibodies and an enzyme-conjugated second antibody. Apolipoprotein E genotyping demonstrates underlying point mutations. Analyses of polymerase chain reaction products are done by allele-specific oligonucleotide probes, restriction fragment length polymorphism, single-stranded conformational polymorphism, the primer-guided nucleotide incorporation assay, or denaturating gradient gel electrophoresis. Detection with primers that either or not initiate amplification is performed with the amplification refractory mutation system. Disparities between phenotyping and genotyping may derive from isoelectric focusing methods that do not adequately separate apolipoprotein E posttranslational variants, storage artifacts or faint isoelectric focusing bands.     

Effect of preoperative supplementation with alpha-tocopherol and ascorbic acid on myocardial injury in patients undergoing cardiac operations

Augmentation of antioxidant defenses may help protect tissues against ischemia-reperfusion injury associated with operations involving cardiopulmonary bypass. In this study we examined the effect of pretreating patients with alpha-tocopherol (vitamin E) and ascorbic acid (vitamin C) or placebo on injury to the myocardium. Seventy-six subjects undergoing elective coronary artery bypass grafting participated in a prospective, double-blind, placebo-controlled randomized trial, receiving either placebo or both 750 IU dl-alpha-tocopherol per day for 7 to 10 days and 1 gm ascorbic acid 12 hours before the operation. Plasma alpha-tocopherol concentrations, raised fourfold by supplementation, fell by 70% after the operation in the supplemented group and to negligible levels in the placebo group. There were no significant differences between the groups with respect to release of creatine kinase MB isoenzyme over 72 hours, nor in the reduction of the myocardial perfusion defect determined by thallium 201 uptake. Electrocardiography provided no evidence of a benefit from antioxidant supplementation. Thus the supplementation regimen prevented the depletion of the primary lipid soluble antioxidant in plasma, but provided no measurable reduction in myocardial injury after the operation.     

浅谈等电位联结的施工

本文讨论了等电位联结,以及等电位联结安装在施工中存在的不足,并提出施工安装中应注意的问题。     

Preparation and characterization of chitosan‐based dispersions

Complexation of chitosan in aqueous solutions by low molecular weight electrolytes is one of the simplest methods for the preparation of aqueous chitosan dispersions. In this work, the influence of storage time, sulfate concentration, method of preparation and surfactant content on some properties of the resultant chitosan dispersions (turbidity, viscosity and zeta potential) was analyzed. Turbidimetry was adequate to monitor the formation of particles, while viscometry was suitable to monitor changes in the dispersing phase. An analysis of the properties of these systems, mainly in terms of particle–particle and macromolecule–macromolecule interactions was carried out. Copyright © 2004 Society of Chemical Industry     

Probing the thermal decomposition process of layered double hydroxides through in situ <Superscript>57</Superscript>Fe Mössbauer and in situ X-ray diffraction experiments

The thermal decomposition properties of Mg–Fe hydrotalcites were studied through in situ ⁵⁷Fe Mössbauer spectroscopy and in situ X-ray diffraction. Abrupt changes in the quadrupolar splitting measured in the Mössbauer spectra revealed a phase transition from the starting lamellar structure to a new crystalline arrangement. By analyzing the Mössbauer parameters we show that the material is highly disordered in the 300–400 °C temperature range. This hypothesis is confirmed by the X-ray results whose diffractograms indicated the collapse of the lamellar structure and the formation of a solid solution.