Adaptive output-feedback tracking of stochastic nonlinear systems

We address the adaptive stabilization and tracking problems for a class of output feedback canonical systems driven by Wiener noises of unknown covariance. Filtered transformation and backstepping techniques are employed in the stochastic control design. We obtain two adaptive controllers that guarantee the global stability in probability for vanishing perturbations or the input-to-state stability in probability for nonvanishing perturbations respectively. The tracking error can converge to a small residual set around the origin in the sense of mean quartic value.     

Electrochemical determination of estradiol using a poly(l-serine) film-modified electrode

A thin film of poly(l-serine) was prepared via electropolymerization for the determination of trace levels of estradiol. In pH 5.0 phosphate buffer, l-serine was oxidized during the cyclic potential sweeps between −0.60 and 2.0 V, forming a thin film at the electrode surface. The electrochemical behavior of estradiol was investigated. The oxidation peak potential of estradiol shifts negatively at the poly(l-serine) film-coated glassy carbon electrode (GCE) compared with that at the bare GCE. Otherwise, the oxidation peak current greatly increases at the poly(l-serine) film-modified GCE. These phenomena suggest that the poly(l-serine) film exhibits catalytic activity towards the electrochemical oxidation of estradiol. Based on this, a sensitive, rapid and simple electrochemical method was proposed for the determination of estradiol. The limit of detection is evaluated to be 2.0 × 10⁻⁸ mol L⁻¹. Finally, this method was successfully used to determine estradiol in blood serum.     

Synthesis and characterization of a novel proton‐exchange membrane for fuel cells operating at high temperatures and low humidities

The synthesis of a p‐toluidine/formaldehyde (PTF) resin was performed, and the effects of the molar ratio of the individual monomers and the polymerization conditions on the structure of the PTF resin were studied. Fourier transform infrared and ¹³C‐NMR spectra were used to characterize the PTF. Wide‐angle X‐ray diffraction patterns revealed the crystalline structures of various PTFs. Polarized optical microscopy revealed that the molar ratio of the monomers had a strong effect on the crystalline morphologies. A longer polymerization time turned out a polymer with a higher intrinsic viscosity and molecular weight, which led to differences in the proton conductivity. All of the PTFs showed a higher proton conductivity than a commercial Nafion membrane at 90–100°C and 0% relative humidity. The proton conductivity of the PTF series could be improved by sulfonation with sulfuric acid and could be maintained after blending with polyurethane. Pure methanol could be used as a fuel source because of the insolubility and nonwetting properties of PTF in methanol to increase the output current density for a PTF membrane electrode assembly. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2008     

Preparation and adsorption behavior of a cellulose‐based,mixed‐mode adsorbent with a benzylamine ligand for expanded bed applications

A novel mixed‐mode expanded bed adsorbent with anion‐exchange properties was explored with benzylamine as the functional ligand. The cellulose composite matrix, densified with stainless steel powder, was prepared with the method of water‐in‐oil suspension thermal regeneration. High activation levels of the cellulose matrix were obtained with allyl bromide because of the relative inertness of the allyl group under the conditions of the activation reaction. After the formation of the bromohydrin with N‐bromosuccinimide and coupling with benzylamine, the activated matrix was derived to function as a mixed‐mode adsorbent containing both hydrophobic and ionic groups. The protein adsorption capacity was investigated with bovine serum albumin as a model protein. The results indicated that the prepared adsorbent could bind bovine serum albumin with a high adsorption capacity, and it showed salt tolerance. Effective desorption was achieved by a pH adjustment across the isoelectric point of the protein. The interactions between the cell and adsorbent were studied, and the bioadhesion was shielded by the adjustment of the salt concentration above 0.1M. Stable fluidization in the expanded bed was obtained even in a 2% (dry weight) yeast suspension. The direct capture of target proteins from a biomass‐containing feedstock without extra dilution steps could be expected with the mixed‐mode adsorbent prepared in this work, and this would be especially appropriate for expanded bed adsorption applications. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

陆相碎屑岩储层隔夹层成因、特征及其识别

陆相储层隔夹层是形成储层流体流动非均质的主要因素之一，也是储层精细表征的重要内容，油田勘探开发实践表明，陆相储层隔夹层主要可分为泥质隔夹层、钙质隔夹层和物性隔夹层三大类。根据这种分类，深入分析和总结了这三类隔夹层成因、岩性特征、分布特征和测井识别特征，并比较其区别，这对以后新老区块隔夹层研究有参考和适用价值。     

真空蒸发沉积VOPc薄膜及磁场对薄膜结构与性能的影响

用真空蒸发制备了酞菁氧钒 (VOPc)薄膜 ,并在磁场中进行了热处理。用X光电子能谱、X射线衍射、紫外 可见吸收光谱、原子力显微镜等手段对制备的薄膜进行了表征。结果表明沉积的酞菁氧钒薄膜为α 型 ,成分接近酞菁氧钒的分子式。制备的薄膜在磁场中进行了热处理 ,发现磁场使酞菁氧钒薄膜性质发生改变 :UV VIS吸收谱Q带发生红移 ;XRD谱图衍射峰强度明显增强 ,峰位略有变化 ;原子力显微镜 (AFM)分析发现晶粒大小无明显变化。以上结果说明磁场的存在使得VOPc分子在热处理过程中发生了定向的排列     

可编程控制器在水压实验机上的应用及设计

可编程控制器在恶劣环境下比继电器，接触器安全，可靠，耐用，以水压试验机编程控制器程序控制为例。阐述了液压，气动。电气联合作用下系统的可编程控制设计方法以及防干扰措施。     

Diamino telechelic polybutadienes for solventless styrene-butadiene-styrene (SBS) triblock copolymer formation

High molecular weight, high functionality diamino telechelic polybutadienes (TPBs) were synthesized by ring-opening metathesis polymerization (ROMP) of 1,5-cyclooctadiene (COD) in the presence of a chain transfer agent, 1,8-dicyano-4-octene, followed by lithium aluminum hydride reduction. Melt coupling of diamino TPB with anhydride-terminated polystyrene (PS-anh) resulted in the formation of styrene-butadiene-styrene (SBS) triblock copolymers; ca. 80% maximum conversion of PS-anh was achieved within 30 s. The results from SAXS, TEM, and rheological measurements of the coupling products confirmed the formation of SBS triblock copolymers having lamellar morphology. A fluorescent-labeled PS-anh was used to study the coupling kinetics by diluting the reactants by the addition of non-functional PS.     

Red Wine Polyphenols for Cancer Prevention

Conventional cancer therapies, the second leading cause of death worldwide, result in serious side effects and, at best, merely extend the patient''s lifespan by a few years. Searching for effective prevention is of high priority in both basic and clinical sciences. In recent decades natural products have been considered to be an important source of cancer chemopreventive agents. Red wine polyphenols, which consisted of various powerful antioxidants such as flavonoids and stilbenes, have been implicated in cancer prevention and that promote human health without recognizable side effects. Since resveratrol, a major component of red wine polyphenols, has been studied and reviewed extensively for its chemopreventive activity to interfere with the multi-stage carcinogenesis, this review focuses on recent progress in studies on cancer chemopreventive activities of red wine polyphenol extracts and fractions as well as other red wine polyphenols, like procyanidin B5 analogues and myricetin.     

Flammability ranking of foliage species by factor analysis of physical and chemical pyric properties

In this paper, factor analysis is introduced to evaluate the flammability of 55 foliage species that may be used in China for construction of the fuel break network of forest strips with lower flammability. Six pyric parameters, i.e. air dry moisture content, absolute dry moisture content, ignition point, ash content, caloric value and extractive content, are measured and used as variables for factor analysis. The covariance analysis shows that four principal factors can be extracted to reflect the flammability in different physical and chemical senses. In terms of the contributions of the four factors to the variances and the physical significance of the relevant parameters, the four factors are, respectively, termed as ‘flaming factor,’ ‘air dry factor,’ ‘ash factor’ and ‘absolute dry factor.’ The stability of the factor analysis method is examined by a different number of samples considered, and the variation degrees of the orderings indicate that the method has high reliability to measure the total flammability of foliage species. The results of the flammability evaluation are verified by comparison with the recommended tree species in the Chinese technology standard. Copyright © 2008 John Wiley & Sons, Ltd.