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.     

Application of ultrasonic waves in activation of microcrystalline cellulose

In this work, microcrystalline cellulose (MCC) was activated with ultrasonic waves. The influences of ultrasonic treatment on the changes of supramolecular structures and morphology structure were studied by WAXS and SEM. The accessibility of the MCC was characterized by water retention value (WRV) and specific surficial area. The influence of ultrasonic treatment on the reactivity of MCC was investigated through the reaction of MCC being oxidized into 2,3‐diadehyde cellulose (DAC) by periodate sodium. The mechanism of the reactivity change of ultrasonically treated MCC was examined. The results showed that the degree of crystallinity of MCC decreased and the degree of polymerization showed little change after treatment with ultrasonic waves. The morphologial variation of the treated MCC was significant when compared with the untreated MCC, which contribute to the improvement of accessibility. The aldehyde content of DAC prepared from ultrasonically treated MCC was improved from 64.19 to 85.00%, indicating that the regioselective oxidation reactivity of MCC was significantly improved. The aldehyde content was found to first increase with time of ultrasonic treatment to a point, and then decrease as time progressed. In addition, the aldehyde content was found to increase with an increase in ultrasonic power. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Influence of post‐treatments on the properties of porous poly(vinyl alcohol) membranes

Porous poly(vinyl alcohol) (PVA) membranes were prepared by a phase‐inversion method. The influence of chemical crosslinking and heat treatments on the swelling degree, resistance to compaction, mechanical strength, and morphology of porous PVA membranes was extensively studied. The crosslinking degree and crystallinity of the membranes, calculated from IR spectra, increased with the treatment time. The porosity, calculated on the basis of swelling experiments, showed a decreasing trend for heat‐treated membranes but remained almost at a constant value for crosslinked membranes. Such a change was further proved with scanning electron microscopy pictures. The behavior was explained by the rearrangement of PVA chains during the heat‐treatment process, which led to morphological changes in the membranes. The mechanical properties of the porous membranes in dry and wet states were measured, and a great difference was observed between crosslinked and heat‐treated membranes in the dry and wet states. The crosslinked membranes showed good mechanical properties in the dry state but became fragile in the wet state. On the contrary, the heat‐treated membranes were more flexible in the wet state than in the dry state. This change was explained by the turnaround of inner stress in the systems during the swelling process. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

组成对MgO-ZrO2-CaO系合成料结构与性能的影响

以脱硅锆、轻烧氧化镁、消石灰为原料，进行了MgO-ZrO2-CaO系原料的合成，研究了化学组成(包括ZrO2含量、CaO／ZrO2比)，烧成温度，杂质等对合成料性能和组织结构的影响。     

烧结原料场大面积扬尘的控制措施

针对烧结原料场大面积扬尘的情况。提出了综合治理措施。着重对适合于烧结用粉状物料的扬尘抑制剂进行了研究。     

技术进步经济效益评价——中国长城铝业公司水泥厂产出增长中技术进步作用的评价

本文通过运用“生产函数法”、“增长速度方程”来定量分析技术进步在长城铝业公司水泥厂产出增长中的作用,从中找出该水泥厂生产经营过程中存在的问题及未来发展方向。     

UNIX系统入侵检测知识库体系结构研究

针对目前应用在UNIX系统中入侵检测知识库适应能力不足的问题.提出了一种适应于不同系统环境的知识库体系结构。检测规则按相应系统与服务类型以模块化形式存储,通过应用配制文件加载。实现了入侵检测知识库的可扩展性.提高了入侵检测知识库的通用性,并且可以提高检测规则的搜索效率。     

Study of the effect of ultrasonic treatment on the surface composition and the flotation performance of high-sulfur coal

This paper highlighted the use of X-ray diffraction, scanning electron microscopy and X-ray fluorescence spectroscopy to investigate the changes on the surface composition of high-sulfur coal and pyrite before and after ultrasonic conditioning. The results showed that ultrasonic conditioning resulted in a decrease in the contents of iron and sulfur in coal, an increase in the content of element carbon, and an increase in the purity of the coal. Conversely, ultrasonic conditioning led to an increase in the content of iron and sulfur in pyrite, a decrease in the impure content of calcium, and a relative increase in the purity of the pyrite after ultrasonic conditioning. This study verified that on the one hand, ultrasonic conditioning can promote the pyrite separation from the high-sulfur coal, with the separated pyrite taking the form of FeS; on the other hand, it can produce a cleaning effect on the surface of coal and pyrite with the consequent increase both in hydrophobicity of coal and hydrophilicity of pyrite. The paper introduced ultrasonic pre-treatment of the slurry and stepped froth removal tests of high-sulfur coal and the study on the yield, ash and sulfur content of clean coal in different phases. The results gave further evidence of the increases both in the rate and the selectivity of flotation. This study shows that ultrasonic conditioning can enhance the performance of de-sulphurization of high-sulfur coal flotation.     

轻质喷涂料的研制

研究了轻质骨料种类，加入量和添加剂等对轻质喷涂料技术及使用性能的影响。并将研制的轻质喷涂料成功地应用于武钢炼铁厂高炉管内壁的喷涂。     

An Application of Interval Methods to Stock Market Forecasting

Stock market forecasting has been a challenging financial research topic for decades. In the literature, there are numerous results based on point methods. However, poor forecasting quality has been a continuous problem. Motivated by the fact that financial data varies within intervals, we apply interval methods on a well known stock pricing model [3] to predict stock market variability as intervals. Empirical results obtained with a few different approaches in this paper consistently suggest that interval forecasts have better overall quality than traditional point forecasts.