Ascorbic Acid-Assisted Eco-friendly Synthesis of NiCo<Subscript>2</Subscript>O<Subscript>4</Subscript> Nanoparticles as an Anode Material for High-Performance Lithium-Ion Batteries

We have synthesized NiCo₂O₄ nanoparticles (NCO NPs) using an ascorbic acid-assisted co-precipitation method for the first time. When NCO NPs are used as an anode material for lithium-ion batteries, the cell exhibits superior lithium storage properties, such as high capacity (700 mA h g^?1 after 300 cycles at 200 mA g^?1), excellent rate capabilities (applied current density range 100–1200 mA g^?1), and impressive cycling stability (at 1200 mA g^?1 up to 650 cycles). The enhanced electrochemical properties of NCO NPs are due to the nanometer dimensions which not only offers a smooth charge-transport pathway and short diffusion paths of the lithium ions but also adequate spaces for volume expansion during Li storage. Hence, this eco-friendly synthesis approach will provide a new strategy for the synthesis of various nanostructured metal oxide compounds, for energy conversion and storage systems applications.     

Practical aspects and experiences Scalable massively parallel algorithms for computational nanoelectronics

There is at present a worldwide effort to overcome the technological barriers to nanoelectronics. Microscopic simulation can significantly enhance our understanding of the physics of nanoscale structures, and constitutes a valuable tool for designing nanoelectronic functional devices. In nanodevices, novel physics effects are used to attain logic functionality which conventional technology can not achieve. Therefore it is necessary to develop quantum-transport simulation methods which include novel physical effects. Moreover, simulation of realistic nanodevices require enormous computing resource, necessitating parallel supercomputing. In this paper, we present massively parallel algorithms for simulating large-scale nanoelectronic networks based on the single-electron tunneling effect, which is arguably the quantum effect of greatest significance to nanoelectronic technology. A MIMD implementation of our simulation algorithm is carried out on a 64-processor nCUBE 2, and a SIMD implementation is carried out on a 16,384-processor MasPar MP-1. By exploiting massive parallelism, both parallel implementations achieve very high parallel efficiency and nearly linear scalability. The result of this work is that we are able to simulate large-scale nanoelectronic network, within a reasonable time period, which would be impractical on conventional workstations.     

多孔沥青混合料粘弹塑性损伤模型

为合理描述多孔沥青混合料在中低温度外界荷载作用下的力学特性,基于增量型本构方程,采用Weibull损伤函数、广义Maxwell粘弹模型与D-P塑性模型,构建了粘弹塑性损伤模型．以此模型为分析手段,对不同温度和加载速率下的单轴压缩应力-应变曲线进行拟合,并分析温度与加载速率对模型参数的影响规律．分析结果表明:多孔沥青混合料粘弹参数随着温度的降低逐步退化成弹性参数,塑性模型中的体积模量和剪切模量也随温度呈现出明显的粘弹特性,塑性应变产生时对应的应变值与损伤应变阙值基本保持一致,温度及加载速率对于混合料的损伤扩展也有显著影响．构建的理论模型可以有效表征多孔沥青混合料在常温和低温下受荷时的力学损伤特性．     

Effects of alternating and direct current in electrocoagulation process on the removal of fluoride from water

BACKGROUND: When direct current (DC) is used in electrocoagulation processes, an impermeable oxide layer may form on the cathode and corrosion of the anode may occur due to oxidation. This prevents effective current transfer between the anode and cathode, so the efficiency of the electrocoagulation process declines. These disadvantages of DC have been reduced by adopting alternating current (AC). The main objective of this study is to investigate the effects of AC and DC on the removal of fluoride from water using an aluminum alloy as anode and cathode. RESULTS: Results showed that removal efficiencies of 93 and 91.5% with energy consumption of 1.883 and 2.541 kWh kL^?1 was achieved at a current density of 1.0 A dm^?2 and pH 7.0 using an aluminum alloy as electrodes using AC and DC, respectively. For both AC and DC, the adsorption of fluoride fitted the Langmuir adsorption isotherm. The adsorption process follows second‐order kinetics and temperature studies showed that adsorption was exothermic and spontaneous in nature. CONCLUSIONS: The aluminum hydroxide generated in the cell removed the fluoride present in the water and reduced it to a permissible level thus making it drinkable. It is concluded that an alternating current prevents passivation of the aluminum anode during electrocoagulation and avoids the additional energy wasted due to the resistance of the aluminum oxide film formed on the anode surface. Copyright © 2010 Society of Chemical Industry     

Viscosity Effects on One-Dimensional Consolidation of Clay

A constitutive relationship for one-dimensional consolidation of clays is presented. It recognizes the importance of structural viscosity and yielding in controlling many of the phenomena associated with the consolidation of clays. The governing equation for the large strain consolidation of clays, incorporating the new constitutive relationship, has been solved using a finite difference technique. The computer program has been verified using laboratory experiments including those performed on an interconnected consolidometer. The laboratory tests and numerical results are used to examine many of the current hypotheses used in predicting field consolidation. The results show that the deformation of thick clays in the field are different from those predicted from a thin laboratory specimen using the square of the drainage length or the uniqueness of the end of primary consolidation concepts. The dominance of the structural viscosity during the primary consolidation stage has been shown to be the main source of the discrepancy.     

Recent Progress on Reduced Graphene Oxide-Based Counter Electrodes for Cost-Effective Dye-Sensitized Solar Cells

Dye-sensitized solar cells (DSSCs) are one type of highly efficient low-cost solar cells among third-generation photovoltaic devices. Replacing the expensive components of DSSCs with alternative inexpensive and earth-abundant materials would further reduce their price in the solar cell market. Recently, graphene-based low-cost counter electrodes (CEs) have been developed, which could serve as a potential alternative to the expensive platinum-based CEs. In this review article, we have summarized recent research on various reduced graphene oxide (rGO)-based composite CE materials, methods for their synthesis, their catalytic activity, and the effective utilization of such CEs in DSSCs. The photovoltaic performance of DSSCs made of rGO-based composite CEs were compared with the reference Pt-based cells, and the photovoltaic parameters are summarized in tables.     

Simulation of fluid flow in granular microstructure using a non-staggered grid scheme

A finite difference numerical scheme has been utilized to simulate fluid flow in granular microstructures. The pixels of their digital images represent the granular microstructure in the finite difference grid. The scheme utilizes a non-staggered grid arrangement, which requires only one finite difference mesh to solve the governing fluid flow equations. As such, the scheme is more efficient when it comes to dealing with non-orthogonal coordinates and complex geometry of boundary conditions such as that of granular microstructure.The numerical scheme is verified by comparing the permeability values of a medium of packed columns to a closed form solution. It is then used to evaluate the permeability coefficients of idealized and natural granular microstructures. It has been found that as the directional aspect ratio increases, the resistance of a particle to fluid flow increases, which results in a decrease in the permeability coefficient. A medium of elliptical particles has higher permeability coefficient than a medium of rectangular particles for the same porosity because of its lower surface area. The permeability anisotropy has been found to increase with an increase in the aspect ratio or a decrease in porosity. Spherical glass beads have been found to have higher permeability coefficients than Ottawa sand and Silica.     

Effects of essential fatty acid deficiency on prostaglandin synthesis and fatty acid composition in rat renal medulla

Studies are reported on the capacity of isolated rat renal papilla (inner medulla) to synthesize and release prostaglandin (PG) E from endogenous and exogenous precursor(s) during development of an essential fatty acid (EFA) deficiency in the rat. Weanling (21-day-old) male Sprague-Dawley rats were fed a fat-free diet supplemented with either 5% hydrogenated coconut oil (HCO) or 5% safflower oil (SO). At approximately 3, 6 and 7 weeks (6, 9 and 10 weeks of age), groups of animals fed each diet were killed for studies of PGE synthesis in the renal papillae. Differences in the fatty acid composition of the papillae lipids of the animals of each group were also determined. The in vitro production of PGE from endogenous precursor(s) was significantly reduced in the papillae from the 6-week-old rats fed the HCO diet compared to the control (SO) rats, and appeared to be near maximally depressed in the 10-week-old animals compared to that of animals fed an EFA deficient diet for over a year in an accessory experiment. Analyses of the fatty acids of the papillae lipids of the HCO groups showed that the levels of 18∶2 and 20∶4 were markedly reduced, and those of 16∶1, 18∶1 and 20∶3 were elevated compared to the controls even in the 6-week-old animals, typical of an EFA deficiency. The papillae lipids of the animals fed the HCO diet were also depleted of their stores of 22∶4ω6. A fatty acid believed to be derived by chain elongation of 20∶3ω9, 22∶3, was found in large concentrations in the papillae triglycerides of the EFA deficient rats. Incubations of exogenous arachidonic acid (20∶4) in homogenates and tissue slices of the papillae of the HCO dietary groups showed that the PG synthetase was not impaired by an EFA deficiency. The rate of PGE synthesis in the papillae of the EFA deficient animals was generally enhanced when exogenous 20∶4 was added, indicating that the concentration of available precursor(s) is a primary factor in the control of PGE synthesis in the papilla of the rat.