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Du Wenwen

Bio: Du Wenwen is an academic researcher from Southeast University. The author has contributed to research in topics: Per capita & Creep. The author has an hindex of 1, co-authored 1 publications receiving 153 citations.
Topics: Per capita, Creep, Health care, Malaria, Artesunate

Papers
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Du Wenwen1, Sun Yangshan1, Min Xuegang1, Xue Feng1, Zhu Min1, Wu Dengyun1 
TL;DR: In this paper, the effects of calcium and rare earth additions to alloy AZ91 on the microstructure and mechanical properties were investigated, and the results indicated that small amounts of calcium addition to AZ91 did not cause the formation of any new phases in the micro-structure, but refined the as-cast micro-structured and increased the thermal stability of the β phase so that the yield strength and creep resistance of the alloy were significantly improved.
Abstract: Effects of calcium and rare earth additions to alloy AZ91 on the microstructure and mechanical properties were investigated. The results indicated that small amounts of calcium addition to AZ91 did not cause the formation of any new phases in the microstructure, but refined the as-cast microstructure and increased the thermal stability of the β phase so that the yield strength and creep resistance of the alloy were significantly improved. Additions of lanthanum-rich misch metal (MM) resulted in the formation of needle-shaped particles, which showed very high thermal stability and did not dissolve into the matrix after the solution treatment at 420 °C for 20 h. The strength as well as creep resistance of the alloy at elevated temperatures was remarkably increased when MM was added combined with calcium. The highest creep resistance was obtained from the alloy with 3% of MM and 0.3% of calcium addition and its steady state creep rate reached as low as 2.69×10 −8 s −1 , one order of magnitude lower than that of alloy AZ91 without MM and calcium additions.

166 citations

Journal ArticleDOI
TL;DR: The use of artesunate over quinine in the treatment of severe malaria in children under 14 years is a highly cost-effective strategy for the healthcare provider in Zambia as discussed by the authors .
Abstract: Malaria exerts a significant economic burden on health care providers and households and our study attempts to make claims on the cost effectiveness of artesunate against quinine in patients under 14 years of age in Zambia. Also, to find the average total costs involved in the treatment of severe malaria in children and their impact on household expenditure.Cost-effectiveness analysis of severe malaria treatment was conducted from a healthcare provider perspective using a Markov model. Standard costing was performed for the identification, measurement and assessment phases with data from quantification reports for anti-malaria commodities as these documents provides drug procurement costs from suppliers and freight costs. Average and incremental cost-effectiveness ratio were estimated and uncertainties were assessed through probabilistic sensitivity analysis.In Zambia severe malaria in children has been shown to account for over 45% of the total monthly curative healthcare costs incurred by households compared to the mean per capita monthly income. The cost of treating severe malaria depleted 7.67% of the monthly average household income. According, to the cost effectiveness analysis the of artesunate with quinine the ICER was $105 per death averted.The use of artesunate over quinine in the treatment of severe malaria in children under 14 years is a highly cost-effective strategy for the healthcare provider in Zambia.

1 citations


Cited by
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Journal ArticleDOI
TL;DR: In this paper, a brief review of historical trends in vehicle weight and automotive magnesium is presented, followed by a discussion of manufacturing and processing, in-service performance, and cost requirements.

495 citations

Journal ArticleDOI
TL;DR: A review of Mg alloys can be found in this article, where the fundamental findings of these efforts, including microstructure, mechanical properties, and strengthening mechanisms are discussed.
Abstract: Advanced Mg alloys require a stable microstructure that maintains good mechanical properties when exposed to high temperatures. On the basis of this demand, the search for new Mg alloys has stimulated the imagination of material scientists. This review's discussion ranges from modifications of commercial Mg-Al- and Mg-Zn-based alloys by Ca and rare earth (RE) elements to the investigations of new families of Mg alloys based on Mg-Sn and Mg-Gd. It reports the fundamental findings of these efforts, including microstructure, mechanical properties, and strengthening mechanisms.

211 citations

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TL;DR: The effect of Ca additions on the microstructure, thermal stability, and mechanical properties of the cast Mg-6Al-0.3Mn alloy (AM60) was investigated in this paper.
Abstract: The effect of 0.5, 1.2, and 2.0 wt.% Ca additions on the microstructure, thermal stability, and mechanical properties of the cast Mg–6Al–0.3Mn alloy (AM60) was investigated. Addition of 0.5 wt.% Ca did not form any new phase but suppressed the discontinuous precipitation of the β-Mg 17 Al 12 phase by being dissolved in both the second phase and magnesium matrix. In the materials containing higher amounts of Ca, however, the Al 2 Ca phase with a lamellar morphology appeared in the microstructure and the volume fraction of β-Mg 17 Al 12 diminished. It was found that Ca generally refines the microstructure and enhances the thermal stability of the alloy. This was documented by the retention of the initial fine dendritic microstructure, hardness, and ultimate shear strength (USS) of the Ca-containing materials after long-term annealing at 673 K. The observed improvements are believed to be caused by the solid solution strengthening of Ca in the Mg matrix, and the particle strengthening effects of the thermally stable Al 2 Ca phase which are formed as an interconnected network. This behavior is in contrast to that of the base material which developed a coarse grain structure with decreased strength and hardness after the same thermal treatment.

143 citations

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TL;DR: A quantum-mechanically derived treasure map which screens solid solution combinations with electronic bonding, structure and volume descriptors for similarity to the ductile magnesium-rare earth alloys to synthesize a surprisingly simple, compositionally lean, low-cost and industry-compatible new alloy.
Abstract: Metals are the backbone of manufacturing owing to their strength and formability. Compared to polymers they have high mass density. There is, however, one exception: magnesium. It has a density of only 1.7 g/cm3, making it the lightest structural material, 4.5 times lighter than steels, 1.7 times lighter than aluminum, and even slightly lighter than carbon fibers. Yet, the widespread use of magnesium is hampered by its intrinsic brittleness. While other metallic alloys have multiple dislocation slip systems, enabling their well-known ductility, the hexagonal lattice of magnesium offers insufficient modes of deformation, rendering it intrinsically brittle. We have developed a quantum-mechanically derived treasure map which screens solid solution combinations with electronic bonding, structure and volume descriptors for similarity to the ductile magnesium-rare earth alloys. Using this insight we synthesized a surprisingly simple, compositionally lean, low-cost and industry-compatible new alloy which is over 4 times more ductile and 40% stronger than pure magnesium. The alloy contains 1 wt.% aluminum and 0.1 wt.% calcium, two inexpensive elements which are compatible with downstream recycling constraints.

140 citations

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TL;DR: A creep resistant Mg alloy ACM720 was subjected to laser surface treatment using Nd:YAG laser equipped with a fiber optics beam delivery system in argon atmosphere.
Abstract: A creep resistant Mg alloy ACM720 was subjected to laser surface treatment using Nd:YAG laser equipped with a fiber optics beam delivery system in argon atmosphere. This treatment was found to be beneficial for the corrosion and wear resistance of the alloy. Long-term linear polarization resistance and Electrochemical Impedance Spectroscopy measurements confirmed that the polarization resistance values of laser surface treated alloy were twice as high as that for the untreated alloy. The improved corrosion resistance was attributed to the absence of the second phase $Al_2Ca$ at the grain boundary, microstructural refinement and extended solid solubility, particularly of Al, in \alpha-Mg matrix owing to rapid solidification. The laser treatment also increased surface hardness two times and reduced the wear rate considerably due to grain refinement and solid solution strengthening.

110 citations