645 research outputs found

    Kinetics of O2 Reduction on Oxide-covered Ni-Cr-Mo Alloys

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    Ni-Cr-Mo alloys exhibit exceptional corrosion resistance and are widely used in chemical processing industries. The reliable performance of these alloys under extreme industrial conditions, are generally attributed to the presence of a passive film on the alloy surface. O2 reduction is the most likely cathodic process able to sustain metal oxidation (corrosion) in industrial environments. However, the kinetics of O2 reduction on these oxide-covered alloys has hardly been studied, despite the possibility it may be the rate controlling process for corrosion, especially localized corrosion. The objectives of this research are to characterize the properties of the oxide film on Ni-Cr-Mo alloys, and to investigate whether O2 reduction occurs on oxide-covered surfaces, and, if it does, the conditions under which it occurs and the mechanism of the reaction. Various surface analytical techniques such as angle-resolved X-ray photoelectron spectroscopy (XPS), synchrotron radiation XPS (SR-XPS), time-of-flight secondary ion mass spectrometry (ToF-SIMS), and SEM are employed to characterize the properties of oxide film on Ni-Cr-Mo alloys as a function of applied potential, temperature and pH. The presence of a layered structure in the passive film (\u3c 5 nm) has been demonstrated on these alloys, with the outermost surface being enriched in Cu (or Cu oxide) and Mo oxide, the intermediate region dominated by Cr/Ni/Cu hydroxides, and the inner region comprising Cr/Ni oxide. A number of electrochemical techniques are used to measure the reduction of O2 on a series of Ni-Cr-Mo alloys (Alloy C22, C2000, C276, C4 and 625) in 5M NaCl solution over the temperature range of 30-90°C. Both potentiostatic and cyclic voltammetric (CV) experiments demonstrate that O2 reduction currents on these alloys are either very small or completely suppressed by the presence of a film grown in the passive region, but revived to different degrees when the film-growth potential was extended into the transpassive region. The impedance properties obtained from EIS measurements show that the polarization resistance reached a maximum in the passive region, and decreased with the increase of film-growth potential in the transpassive region, due to the oxidative injection of cation defects. Keywords: Ni-Cr-Mo alloys, passive film properties, kinetics, O2 reduction

    Path Selection of the Legalization for Same-Sex Marriage of China

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    With the gay movement rising in the world, the rights protection of Chinese homosexuals is more cause for concern, including Same-sex marriage problem has become a focus of the rights protection. As a way of life, gay marriage will inevitably impact on the traditional concept of marriage and family

    Interpretation of Predicament and Its Cause of China Campus Security Legislation

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    Chinese campus accidents have occurred frequently in recent years with more serious nature and wider scope. The lack of legislation makes it difficult to deal with the campus injury accidents in the judicial practice. In order to protect the legitimate rights and interests of students and schools and maintain normal teaching order, accelerating the pace of campus safety legislation is a new task for the legislature to research and solve

    Estimating China’s Energy and Environmental Productivity Efficiency: A Parametric Hyperbolic Distance Function Approach

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    Since the beginning of this century, China’s annual GDP growth is over 9%. This growth is fueled by large increases in energy consumption, led by a coal-dominated energy structure, and associated with higher sulfur dioxide emissions and industry dust. In 2008, China accounted for over 17% of the world’s total primary energy consumption and accounts for nearly three-quarters of global energy growth. At an average annual energy growth rate over 12% since 2000, China’s future share of primary energy consumption will continue to increase. A consequence of this growth is China becoming the global leader in sulfur and carbon dioxide emissions. To deal with these energy and environmental challenges, the government set energy saving and pollution reduction target objectives in the 11th Five Year Plan (2006-2010): relative to 2005 by 2010, saving national energy use per unit of GDP by 20% and reducing the country’s primary pollution emissions by 10%. These targets were then disaggregated into energy saving targets for each province. With this disaggregated scheme, similar to country’s target, 20 provinces were assigned a 20% energy saving target, seven provinces were assigned targets below 20%, varying from 12% to 17%, and four provinces were given targets above 20%. These allocation were generally not guided by technical or economic efficiency, and thus may not be optimal from the perspectives of equity and efficiency. Historically less energy efficiency provinces may have more potential to reduce their energy consumption and pollution emissions, while higher efficiency provinces may have less potential. The major objective is to determine the optimal targets for each province required to comply with the national Five Year Plan target. A comparison of the estimated optimal with the current government targets will then reveal the value of incorporating economic theory into the decision calculation of setting disaggregate targets. Determining optimal targets requires consideration of both desirable and undesirable comes from alternative feasible targets. An objective is then to delineate these comes as criterion for selection. The procedure employed is a parametric hyperbolic distance function approach with a translog specification. This procedure provides the flexibility of using energy, labor, and capital stock as inputs to produce the desirable output (GDP) and the undesirable output (sulfur dioxide emissions). The procedure will address the objectives by simultaneously estimating both the desirable and undesirable comes. Specifically, the production frontier and environmental productivity efficiency are estimated for each province. The hyperbolic distance function enables the estimation of efficiency scores by incorporating all types of inputs and outputs, and only requires information on input and outputs quantities but not on prices, making it possible to model the emissions in the production process, given nonmarket characteristics of emissions. Based on these parametric estimations, the optimal targets are determined. The trajectory of obtaining these optimal targets for each province is determined by estimating how each province can improve its productive performance through increasing its desirable output and reducing its undesirable output, while simultaneously saving energy inputs. The results provide an empirical measurement of energy efficiency with maximum potential of energy saving for each province at a given technology considering the diverse economic, industry, and energy consumption patterns in the provinces. With a panel data of 29 provinces in China from 2000-2007, the hyperbolic distance function allows us to measure environmental productivity change over time, and then decompose this environmental productivity change into efficiency change, which is the movement toward the frontier, and technical change, which is the shift of the frontier. These further analyses help us identify potential different contributions of productivity growth for each province in China, and examine how the energy saving program will affect the environmental productivity growth for each province.environmental productivity efficiency, hyperbolic distance function, China's energy policy, Environmental Economics and Policy, Productivity Analysis, Resource /Energy Economics and Policy,

    The Interactions of N

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    A generalized (2+1)-dimensional variable-coefficient KdV equation is introduced, which can describe the interaction between a water wave and gravity-capillary waves better than the (1+1)-dimensional KdV equation. The N-soliton solutions of the (2+1)-dimensional variable-coefficient fifth-order KdV equation are obtained via the Bell-polynomial method. Then the soliton fusion, fission, and the pursuing collision are analyzed depending on the influence of the coefficient eAij; when eAij=0, the soliton fusion and fission will happen; when eAij≠0, the pursuing collision will occur. Moreover, the Bäcklund transformation of the equation is gotten according to the binary Bell-polynomial and the period wave solutions are given by applying the Riemann theta function method

    Overexpression of an isoform of AML1 in acute leukemia and its potential role in leukemogenesis

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    AML1/RUNX1 is a critical transcription factor in hematopoietic cell differentiation and proliferation. From the _AML1_ gene, at least three isoforms, _AML1a_, _AML1b_ and _AML1c_, are produced through alternative splicing. AML1a interferes with the function of AML1b/1c, which are often called AML1. In the current study, we found a higher expression level of _AML1a_ in ALL patients in comparison to the controls. Additionally, AML1a represses transcription from promotor of macrophage-colony simulating factor receptor (M-CSFR) mediated by AML1b, indicating that AML1a antagonized the effect of AML1b. In order to investigate the role of _AML1a_ in hematopoiesis and leukemogenesis _in vivo_, bone marrow mononuclear cells (BMMNCs) from mice were transduced with AML1a and transplanted into lethally irradiated mice, which develop lymphoblastic leukemia after transplantation. Taken together, these results indicate that overexpression of AML1a may be an important contributing factor to leukemogenesis