Effects of Hot Extrusion and Heat Treatment on Mechanical Properties and Microstructures of AZ91 Magnesium Alloy

AbstractThe effects of heat treatment on the microstructure, tensile property and fracture behavior of as-extruded AZ91 magnesium alloy were studied with OM and SEM. The results show that the grains of as-cast AZ91 alloy are refined by hot extrusion due to dynamic recrystallization, and the mechanical properties are improved obviously. The ductility is significantly enhanced after solution treatment of the as-extruded AZ91 alloy, tensile strength is almost the same as before, and hardness is significantly reduced after solution treatment and artificial aging treatment. The tensile strength reduced and the ductility is significantly enhanced of as-extruded after annealing processes. The fracture surface of as-extruded AZ91 magnesium alloy has the mixed modes of ductile and brittle characteristics. But after T6 or annealing treatment, the dimple number increases evidently

Effects of Flos carthami on CYP2D6 and on the Pharmacokinetics of Metoprolol in Rats

Flos carthami is a traditional Chinese herbal medicine. Clinically, the Flos carthami Injection has been used concomitantly with other Western drugs and may be used concomitantly with β-blockers, such as metoprolol, to treat cerebrovascular and coronary heart diseases, in China. Metoprolol is a CYP2D6 substrate and is predominantly metabolized by this isozyme. However, we do not know whether there is an effect of Flos carthami on CYP2D6 and the consequences of such an effect. Concern is raised regarding the possible herb-drug interaction. In this report, the effects of Flos carthami on the activity of CYP2D6 in vivo and in vitro and on the pharmacokinetics of metoprolol, in rats, are investigated. To assess the inhibitory potency of Flos carthami, the concentration associated with 50% inhibition (IC50) of dextromethorphan metabolism was determined based on the concentration-inhibition curves. The inhibitory effect of Flos carthami on CYP2D6 was also compared with cimetidine in vitro. Flos carthami could significantly inhibit CYP2D6 in rats both in vitro and in vivo (P < .05) and could slow down the metabolic rate of metoprolol as suggested by prolonged t1/2 (67.45%), by increased Cmax (74.51%) and AUC0−∞ (76.89%). These results suggest that CYP2D6 is a risk factor when Flos carthami is administered concomitantly with metoprolol or other CYP2D6 substrates

Experimental investigation on permeability and mechanical deformation of coal containing gas under load

Coalbed effective permeability is widely used as a primary index to evaluate gas-drainage effect in CBM exploitation field. However, it seems to be difficult to obtain by the reason of dynamic change in close relationship with crustal stress, methane pressure, porosity, and adsorption. Due to their dissimilar adsorption properties and tectonic deformation degrees, different types of coal containing gas have various stress-strain and gas seepage curves. The paper presents the experimental investigations of the dynamic relationship between coal permeability and deformation under load. In this work, stress-strain and permeability investigations were performed using anthracite lump with a vitrinite reflectance of about 3.24% at various pressures and temperatures. The permeability (including the initial, minimum, and maximum) decreased with increasing temperature. At a constant confining pressure, the strains in different directions almost all increased with increasing axial stress and decreased with increasing pore methane pressure during the prefracture stage. At a constant pore pressure, the compression strength of the coal specimens increased approximately linearly during the prefracture stage and sharply decreased during the postfracture stage, while the permeability decreased rapidly and then increased slowly during the prefracture and remained stable during the postfracture stage. The permeability of the coal specimens mainly depended on the inner fissures. The permeability was greater during the postfracture than that during the prefracture stage. At the same temperature, the gas seepage curve of each coal specimen could be divided into three sections: decreasing, increasing, and constant sections. The necessary time for the permeability to reach a steady state increased as the confining and pore pressures increased. At high confining pressures (i.e., 6 MPa and 8 MPa), no significant differences between the methane seepage velocities of the specimens were evident, and their seepage curves were similar to prefracture. However, clear differences were observable at the postfracture stage. The seepage abilities of the coal specimens were more sensitive to stress than temperature in the same condition

The comparison between China and UK of the construction of city community sports service system in the scope of eco-civilization

The construction of urban community sports public service is not only an important part of urban community public service management, but also an important content of building the national fitness public service system. In this paper, the author analyse the comparison between China and UK of the construction of city community sports service system in the scope of eco-civilization. With the rapid development of society and economy, people's demand for sports is more and more urgent, and community sports is the most effective and direct way to meet people's needs. Therefore, it has practical significance to study the construction and management mode of community sports facilities

Mechanism of Exact Transition between Cationic and Anionic Redox Activities in Cathode Material Li2FeSiO4.

The discovery of anion redox activity is promising for boosting the capacity of lithium ion battery (LIB) cathodes. However, fundamental understanding of the mechanisms that trigger the anionic redox is still lacking. Here, using hybrid density functional study combined with experimental soft X-ray absorption spectroscopy (sXAS) measurements, we unambiguously proved that Li(2- x)FeSiO4 performs sequent cationic and anionic redox activity through delithiation. Specifically, Fe2+ is oxidized to Fe3+ during the first Li ion extraction per formula unit (f.u.), while the second Li ion extraction triggered the oxygen redox exclusively. Cationic and anionic redox result in electron and hole polaron states, respectively, explaining the poor conductivity of Li(2- x)FeSiO4 noted by previous experiments. In contrast, other cathode materials in this family exhibit diversity of the redox process. Li2MnSiO4 shows double cationic redox (Mn2+-Mn4+) during the whole delithiation, while Li2CoSiO4 shows simultaneous cationic and anionic redox. The present finding not only provides new insights into the oxygen redox activity in polyanionic compounds for rechargeable batteries but also sheds light on the future design of high-capacity rechargeable batteries

Characteristics’ relation model of asphalt pavement performance based on factor analysis

Pavement performance of asphalt is an important criterion for road engineering quality evaluation. Proposed research paper designed an orthogonal experiment using three asphalt mixtures, including SMA-13, AC-20 and ATB-25 to get their relation models and evaluate pavement performances. Totally twenty-seven samples from private companies have been selected and seven crucial parameters are analyzed via factor analysis. Further analysis concluded three main factors corresponding to the three main pavement performance parameters (i) high-temperature stability (ii) durability and (iii) shear resistance. Based on scores of each asphalt mixture’s 3D scatter-map is plotted. Analysis found the relationship between three above-mentioned parameters. Relationship between the three main performance parameters has been established using graphical analysis. A separation plane can define the different types of asphalt mixtures’ scatter distribution area, and get the regression equation for the plane. Based on the equation for the plane a more intuitionistic model has been made which describes the relationship of asphalt pavement performance. Keywords: Road engineering, Asphalt, Index correlation, Surface fitting, 3D-mode

A Study on the Effectiveness of China’s Rural Land Reform Policies since the 1990s The Case of Qidu Town of Suzhou, Jiangsu Province

Since the reform and opening-up of China, the nation’s rural development has been accompanied by a series of land reform policies, largely concerning agricultural land, homestead land and rural construction land. Have rural land reform policies achieved their original objectives and contributed to the socio-economic and spatial development of rural China? To answer these questions, this paper examines the case of Qidu Town of Suzhou, Jiangsu Province and conducts a three-step analysis of the effectiveness of both national- and local-level rural land reform policies. It first reviews the policies to clarify their economic, social and spatial objectives. It then quantitatively analyses the economic, social and spatial performance of these policies in Qidu Town since 1998; this analysis is performed with economic, social and land-use data and quantitative-analysis methods. Finally, it assesses the policies’ effectiveness by comparing their objectives with the results of the quantitative analyses. It concludes that at both the national and local levels, the effectiveness of land reform policies has varied across different periods, across different measures, and between one another. The reason for this variation rests predominantly on the attitudes of the affected villages and villagers. By taking the town, China’s basic administrative unit, as the research object and bringing spatial performance into policy effectiveness, this research seeks to develop a methodology for objective and accurate assessments of the effectiveness of rural land reform policies