Porous sulfated metal oxide SO<Subscript>4</Subscript><Superscript>2−</Superscript>/Fe<Subscript>2</Subscript>O<Subscript>3</Subscript> as an anode material for Li-ion batteries with enhanced electrochemical performance

Sulfated metal oxide SO₄ ^2?/Fe₂O₃ was prepared by a novel facile sol–gel method combined with a subsequent heating treatment process. The as-synthesized products were analyzed by XRD, FTIR, and FE-SEM. Compared with the unsulfated Fe₂O₃, the agglomeration of particles has been alleviated after the incorporation of SO₄ ^2?. Interestingly, the primary particle size of the SO₄ ^2?/Fe₂O₃ (about 5 nm) is similar to its normal counterparts even after the calcination treatment. More importantly, SO₄ ^2?/Fe₂O₃ exhibits a porous architecture, which is an intriguing feature for electrode materials. When used as anode materials in Li-ion batteries, SO₄ ^2?/Fe₂O₃ delivered a higher reversible discharge capacity (992 mAh g^?1), with smaller charge transfer resistance, excellent rate performance, and better cycling stability than normal Fe₂O₃. We believed that the presence of SO₄ ^2? and porous architecture should be responsible for the enhanced electrochemical performance, which could provide more continuous and accessible conductive paths for Li⁺ and electrons.     

A high-resolution gas-kinetic scheme with minimized dispersion and controllable dissipation reconstruction

In order to simulate multiscale problems such as turbulent flows effectively, the high-order accurate reconstruction based on mini- mized dispersion and controllable dissipation (MDCD) is implemented in the second-order accurate gas-kinetic scheme (GKS) to improve the accuracy and resolution. MDCD is firstly extended to non-uniform grids through the modification of dissipation and dispersion coefficients for uniform grids based on the local stretch ratio. Remarkable improvements in accuracy and resolution are achieved on general grids. Then a new scheme, MDCD-GKS is constructed, with the help of MDCD reconstruction, not only for conservative variables, but also for their gradients. MDCD-GKS shows good accuracy and efficiency in typical numerical tests. MDCD-GKS is also coupled with the improved delayed detached-eddy simulation (IDDES) hybrid model and applied in the fine simulation of turbulent flow around a cylinder, and the prediction is in good agreement with experiments when using the relatively coarse grid. The high accuracy and resolution of the developed GKS guarantee its high efficiency in practical applications.     

Thermodynamic analysis of shark skin texture surfaces for microchannel flow

The studies of shark skin textured surfaces in flow drag reduction provide inspiration to researchers overcoming technical challenges from actual production application. In this paper, three kinds of infinite parallel plate flow models with microstructure inspired by shark skin were established, namely blade model, wedge model and the smooth model, according to cross-sectional shape of microstructure. Simulation was carried out by using FLUENT, which simplified the computation process associated with direct numeric simulations. To get the best performance from simulation results, shear-stress transport k-omega turbulence model was chosen during the simulation. Since drag reduction mechanism is generally discussed from kinetics point of view, which cannot interpret the cause of these losses directly, a drag reduction rate was established based on the second law of thermodynamics. Considering abrasion and fabrication precision in practical applications, three kinds of abraded geometry models were constructed and tested, and the ideal microstructure was found to achieve best performance suited to manufacturing production on the basis of drag reduction rate. It was also believed that bionic shark skin surfaces with mechanical abrasion may draw more attention from industrial designers and gain wide applications with drag-reducing characteristics.     

Compressive strength and hydration characteristics of high-volume fly ash concrete prepared from fly ash

Journal of Thermal Analysis and Calorimetry - This paper investigated the feasibility of replacing cement with fly ash (FA) mass ratios ranging from 40 to 70% to produce high-volume FA (HVFA)...     

Influence of the Addition of Nano-porous Graphite/Parafffin Additive on the Wear Properties of Phenol-Formaldehyde Resin Composites

Phenol-formaldehyde resin (PF) composites with a nano-porous graphite additive (NPGA) in various contents were fabricated and the wear behaviors under low and high sliding speeds were studied. The addition of NPGA significantly improved the wear resistance of the PF. The specific wear rates of PF composites under low sliding speed first decreased with increasing NPGA and then slightly increased when the NPGA content surpassed 15?wt%; the specific wear rate of the composite with 15?wt% NPGA was reduced by 77% compared with the neat PF. Under high sliding speed the specific wear rates of the composite material decreased continuously with increasing NPGA content and the maximum wear resistance of the composite with 20?wt% NPGA was more than 12 times that of the neat phenolic resin. The results are attributed to the combined effects of load-capacity and the lubrication role of the included NPGA. The surface morphology of the worn surface was characterized, and the wear mechanism for the composites is discussed.     

A Directly Patternable,Click‐Active Polymer Film via Initiated Chemical Vapor Deposition

Click‐active surfaces patterned at 200 nm resolution are demonstrated using the dual functional polymeric film, poly(propargyl methacrylate) (PPMA). The commercially available monomer of propargyl methacrylate (PMA) is polymerized in a single step by initiated chemical vapor deposition (iCVD). FT‐IR and X‐ray photoelectron spectroscopy confirm retention of the click‐active acetylene functional group in the bulk and surface of the iCVD film, respectively. Treating substrates with silane coupling agents prior to deposition results in grafting of iCVD PPMA polymers onto various inorganic surfaces. This grafting technique provides the chemical and mechanical stability required for the PPMA layer to survive the subsequent wet chemical steps used for click functionalization. Successful attachment of an azido‐functionalized coumarin dye is demonstrated. Moreover, the PPMA film displays direct positive‐tone sensitivity to e‐beam irradiation, which enables e‐beam patterning without the use of a resist layer. Direct e‐beam exposure of the multifunctional PPMA iCVD layer results in a 200 nm pattern to which quantum dot nanoparticles are selectively conjugated on the substrates by click chemistry.

     

A chaotic maps-based authenticated key agreement protocol with strong anonymity

In wireless communication environments, the authenticated key agreement with user anonymity is important. Recently, many chaotic maps-based anonymous authenticated key agreement protocols have been proposed. Tseng et al. applied Chebyshev chaotic maps to propose an anonymous key agreement protocol. Unfortunately, Niu et al. demonstrated that Tseng et al.’s protocol cannot protect the user anonymity and it suffers from insider attacks. Xue et al. improved Tseng et al.’s protocol. However, we have found that their improved protocol still cannot provide strong anonymity and it is vulnerable to the man-in-the-middle attack. To remove these weaknesses, we have proposed a novel chaotic maps-based authenticated key agreement protocol. The proposed protocol cannot only resist these attacks, but also provide strong anonymity.     

Practical scheme for remote preparation of a photon-photon entangled state

We present a scheme to remotely prepare a photon--photon entangled state via entanglement swapping in cavity QED. Using two successive processes of appropriate atom--cavity interaction and subsequent measurements, we obtain the entangled state with certain probability.     

Basic properties of an rf SQUID involving two Josephson junctions connected in series

We have studied the basic characteristics of a radio frequency superconducting quantum interference device (rf SQUID) involving two Josephson junctions connected in series, the case for the widely used grain boundary junction (GBJ) rf SQUID. It is found that the SQUID properties are determined mainly by the weaker junction when the critical current of the weaker junction is much lower than that of the other junction. Otherwise, the effect of the other junction is not negligible. We also find that only when the hysteresis parameter β is less than 1-α, where α is the critical current ratio of the two junctions, will the SQUID operate in the nonhysteretic mode.