Totally found 512 items.

  • [资讯] Li3Ti4CoCrO12, a new substituted lithium titanium compound as anode material for lithium ion batteries
    A new compound Li3Ti4CoCrO12, used as an anodic material for LIBs, was successfully prepared by nanomilling enhanced solidstate reaction method. Retrieved refinement of the Xray diffraction (XRD) profile indicated that the material crystallizes in an ordinary Fd3m lattice space group in which the substituted ions Co2 and Cr3 occupy the original Li and Ti (4) lattice positions, respectively. Upon cyclic voltammetry (CV) measurement, the sample showed a pair of redox process peaking at 1.44 V1.53 V, implying that only Ti3Ti4 redox pair was involved in the electrochemical process. Electrochemical impedance spectroscopy (EIS) test suggested that both the low interfacial resistance (8.56 Omega) and the high Li ion diffusion (9.86 x 10(10) cm(2).S1), caused by the mesoporous nature of the anode powder, could be regarded as the important factors for the outstanding electrochemical behavior of the new anode material. The results imply that the synthesized compound Li3Ti4CoCrO12 has high potential for the application in lithium secondary batteries.
  • [资讯] Soft elastomeric composite materials with skin-inspired mechanical properties for stretchable electronic circuits
    The stretchable version of electronic circuits harnesses commercial chip scale components to achieve complex functionality and mechanical deformability, which represents an emerging technology to expand the application of conventional electronics on rigid wafers. The bottleneck lies in the lack of a robust approach for the collective integration of offtheshelf components into a reliable system. In this study, an elastomeric composite material with skinlike mechanical responses and spatially heterogeneous rigidity is reported as an attractive platform for stretchable circuit systems. The approach utilizes a high modulus microstructure embedded in the matrix of a soft elastomer to achieve programmable mechanical properties, thereby offering selective strain isolation for fragile components and overall protection against excessive loads. A low cost procedure involving laser ablation and blade coating is established to create the composite material matching with the circuit design. In addition, ultrasonic atomization of liquid metal into microparticles allows flexible preparations of deformable conductors in the forms of interconnects and contacts. An LED matrix is demonstrated as a prototype circuit system with excellent durability to withstand repetitive stretching and external impacts. Stretchable circuit systems based on soft elastomeric composite materials may find potential uses in health monitoring, mechatronic prosthetics, and soft robotics.
  • [资讯] Preparation of PAN-based carbon fiber@MnO 2 composite as an anode material for structural lithium-ion batteries
    Carbon fiber@MnO 2 composite (CF@MnO 2 ) has been successfully synthesized based on the redox mechanism, and the morphological and electrochemical features are also studied. As a promising anode material for structural lithiumion batteries (SLIBs), CF@MnO 2 composite presents a coulombic efficiency of over 99% and good cyclic ability. It performs a high reversible capacity of 648 mAh g 1 after 150 cycles at a current density of 100 mA g 1 , approximately 2.5 times as high as the pure CF (~ 260 mAh g 1 ). Moreover, the images of attained composite after the cycle show the fibrous structure do not change much, which verifies it retains good cycle stability. The superior electrochemical performance of the CF@MnO 2 composite can be attributed to the unique hierarchy architecture and the synergistic effect between MnO 2 and CF, which can effectively alleviate the volume expansion of MnO 2 during the lithium insertionextraction.
  • [资讯] Heterostructural SnO/SnO2@C composite fabricated from tin-based coordination polymer as high-performance anode materials for lithium ion batteries
    We report a simple carbonization strategy to obtain a composite structured SnOSnO2 particles encapsulated into carbon matrix from a tinbased coordination polymer precursor at 500 degrees C carbonization. SnOSnO2@C electrode delivers a capacity of 601.7 mAh g(1) at 100 mA g(1) after 50 cycles and a high capacity retention of 84.6% after 400 cycles, which is far superior to the precursor Sn1 electrode. The excellent electrochemical performance of SnOSnO2@C could be mainly attributed to the abundant carbon and welldispersed SnOSnO2 particles which can improve the electronic conductivity and provide a path for the migration of electrons and ions. (C) 2019 Elsevier B.V. All rights reserved.
  • [资讯] lexural performance of FRP-plated RC beams using H-type end anchorage
    This paper investigates the performance of H-type end anchorage on the flexural strengthening of Fiber Reinforced Polymer (FRP) plated reinforced concrete (RC) beams. The H-type end anchorage (EA) consists of an anchorage section, a connection section and a deformation section. In the experimental study, the H-type EA was installed at the ends of FRP plate, and the FRP-plated RC beams were subjected to four-point bending load. The strengthening mechanism of H-type end anchorage mainly depends on the width of its deformation part, which further determines the overall axial stiffness of the end anchorage. The effect of H-type end anchorage on the flexural performance was evaluated in terms of critical loads, failure mode, deflection, ductility and strain behavior of various materials, all showing great improvement as compared to the FRP-plated RC beams without end anchorage. H-type end anchorage was found to be activated after certain thresholds of load was reached, and the elongation became excessive after its yielding. Finally, an analytical model was proposed and verified by the experimental results to estimate the ultimate load and failure mode of the EA-strengthened RC beams.
  • [资讯] Investigations on partially reduced graphene oxide capped sulfur/polyaniline composite as positive electrode material for lithium-sulfur battery
    A ternary sulfur (S)polyaniline (PAni)partially reduced graphene oxide (prGO) composite material has been prepared via simple heat treatment. The combined effect of prGOPAni performs multiple roles like serving as a conducting additive and as a porous adsorbing agent to prevent dissolution of polysulfide in the composite. The prepared material has been characterized for its structural and morphological studies using xray diffraction, Fourier transform infrared spectroscopy, Raman analysis and Scanning electron microscopy. Electrochemical measurements have been studied by cyclic voltammetry and chargedischarge analyses with the potential window of 1.53.0 V. The SPAniprGO composite cathode delivers an initial discharge capacity of 972 mAh g(1) at 0.1 C rate and it sustains 645 mAh g(1) at 50th cycle. The improved electrochemical performance of SPAniprGO cathode in lithium sulfur battery is mainly attributed to the combined effect of partially reduced graphene oxide and polyaniline.
  • [资讯] Parameters influencing the impact response of fiber-reinforced polymer matrix composite materials: A critical review
    The damage of fiber reinforced polymer matrix composite materials induced by impact load is one of the most critical factors that restrict extensive use of these materials. The behavior of composite structures under transient impact loading and the ways to enhance their characteristics to withstand this type of dynamic loading might be of specific significance in the aerospace sector and other applications. This paper critically reviews the important parameters from the published literature influencing the impact resistance and the damage mechanics of fiberreinforced composite materials. Firstly, the paper reviews the influence of impact velocity on various failure modes. Following this, a comprehensive review on the four key parameters specifically material, geometry, event and the environmentalrelated conditions that affect the structural behavior of fiber reinforced polymer matrix composites to impact loading is discussed. The review further outlines areas to improve the impact damage characteristics of composites and then conclude with a summary of the discussion on the future work relating to the most influencing parameters.
  • [资讯] A reassessment of mycophenolic acid as a lead compound for the development of inhibitors of chikungunya virus replication
    Mycophenolic acid (MPA) has been previously reported as an inhibitor of the chikugunya virus (CHIKV) with an EC50 value of 0.2 μM. We used MPA as a lead compound designing and synthesizing a series of isatins and benzolactones in a typical medicinal chemistry program. The synthesis and testing of 19 derivatives produced compounds with no desired activity which prompted us to retest the lead compound, MPA. We can reveal that MPA shows no anti-CHIKV activity and therefore needs to be reassessed as a lead compound for this target.
  • [资讯] Detecting Water in Composite Sandwich Panels by Using Infrared Thermography
    Honeycomb composite structures widely used in aviation are sturdy and light-weight but they may accumulate water from the atmosphere during aircraft operation. The presence of water in honeycomb cells leads to a higher airplane mass and excessive corrosion of aluminum cores, while the frozen water endangers panel integrity. This work describes the use of infrared thermography for detecting water trapped in aviation honeycomb cells. [1] V.P. Vavilov, D.A. Nesteruk, Detecting water in aviation honeycomb structures: the quantitative approach, J. Quant. InfraRed Thermography 1 (2004) 173-184.10.3166/qirt.1.173-184 [2] V.P. Vavilov, D.D. Burleigh, Review of pulsed thermal NDT: Physical principles, theory and data processing, NDT & E International 73 (2015) 28-52. 0963-869510.1016/j.ndteint.2015.03.003
  • [资讯] Computational analysis of a sandwich shield with free boundary inserted fabric at high velocity impact
    In this paper, a novel hybrid composite shield to protect space structures from hypervelocity impact of micrometeoroid and space debris is proposed. The finiteelement model of the proposed shield was constructed and finite-element analysis was conducted to approximate the energy absorption rate. Before the final model analysis, analysis of each component including the aluminum plate (front plate), PMMA plate (rear plate), and intermediate layer of fabric was performed, verifying the finite-element model of each component. The material properties used in the analysis were predicted material property values for high strain rates. The analysis results showed that, other than the fabric, the energy absorption rate of each component was in agreement. Afterwards, the finite-element model of the hybrid composite shield was constructed, where it was analyzed for the constrained and unconstrained fabric boundary condition cases. Through the finite-element analysis, the fiber pullout mechanism was realized for the hybrid shield with free boundary inserted fabric, and it was observed that this mechanism led to energy absorption increase.