Abstract: 40CrMnSiB steel is a new type of B-containing structural steel. To research the effect of tempering temperature on mechanical properties of 40CrMnSiB steel, forging, normalizing and quenching are carried out on material firstly, then temper respectively at 350°C400°C450°C500°C550°C600°C650°C and 700°C. After tempering, mechanical properties are tested. Also the hardness, along a radius of section, of the material after tempering at 300°C is measured and the effect of tempering temperature on mechanical properties of 40CrMnSiB steel is analyzed. The results show that: the mechanical properties of 40CrMnSiB steel is sensitive to temper temperature, properties range a large scale with temper temperature; it has a strength of 1800MPa (or more) with good ductility, toughness and fine comprehensive mechanical properties; the hardness of the material after tempering at 300°C is over 50HRC, hardenability is fine, the main microstructure is martensite.
Abstract: This work experimentally investigated the material effect of heat sinks of LED lamps on the heat transfer and illumination characteristics under the free-convection condition. The experimental results indicated that the heat-transfer capacity of the pure aluminum-alloy heat sink was better than those of the composite-graphite heat sinks. However, the cost and weight of the composite-graphite heat sinks were reduced much more by comparing with those of the pure aluminum-alloy heat sink. Besides, the illuminations of these test heat sinks were similar after 2000-hour lighting continuously. Therefore, the composite-graphite heat sink is useful for the cooling of the LED lamp and the electric equipment. It has large potential in the relevant markets.
Abstract: PVP/[Sr (NO3)2+Al (NO3)3+Eu (NO3)3+Dy (NO3)3] composite nanofibres were prepared by electrospinning technique. SrAl2O4:Eu2+, Dy3+ luminescent nanofibers were synthesized by calcination under a reducing atmosphere at 1100°C. The luminescent nanofibers were characterized by XRD, SEM, FTIR, TG, fluorescence spectrophotometer, respectively. The experimental results showed that the products are with monoclinic SrAl2O4 crystal structure, the diameter of nanofibers is about 100nm and the size is uniformly distributed. The luminescent nanofibers emit bright blue fluorescence of 470nm in wavelength of Eu2+ ion characteristic emission under the excitation of 365nm in wavelength of ultraviolet ray. The position of emission peak exhibit blue shift in some degree compared with that of bulk SrAl2O4:Eu2+, Dy3+.
Abstract: In this work, a series of theoretical methods were employed to investigate the reaction mechanisms of ribosomal peptide bond formation catalyzed by peptidyl transferase. For the studies described in this paper, reaction pathways and free energy barriers for the model reaction of the peptide bond synthesis were studied by performing Ab initio calculation. Two self-consistent reaction field (SCRF) methods were used to calculate of the whole reaction pathway. These results show that the present theoretical reaction mechanism is a potential and competitive one for the reaction modeling of the ribosomal peptide synthesis.
Abstract: The molecular dynamic method and interface diffusion theory are used to simulate Ni/Al metal interface diffusion. One of the unit cells containing 576 Ni atoms and 128 Al atoms is chosen and computed under different temperatures (600K, 700K, 800K, 900K, 1000K, 1100K, 1200K, 1300K), respectively. We mainly analyze the position image of the interface diffusion atoms of Ni/Al interface reaction and the radial distribution function curve of the selected region, after the molecular dynamics program running 1200000 steps, under different temperatures, at initial diffusion time.
Abstract: A one-port waveguide method and related apparatus based on the multi-state techniques is descried in this paper. This method measures only the magnitude and phase information for the reflection coefficients of four-state before and after the samples under test being loaded. On the basis of such data, the complex permittivity and permeability of the samples can be simultaneous calculated by software programmed according to the related theories discussed herein. In addition, the error analysis is also discussed in this paper. The proposed method is applicable to measure magnetic and/or medium-to high-loss materials, hence it is suitable to characterize the properties of radar absorbing materials.
Abstract: Wool spherical-like Bi2WO6 nanoarchitectures were synthesized by hydrothermal method with using bismuth nitrate and sodium tungstate as raw materials. Ag was deposited on the surface of Bi2WO6 by a photoreduction process. The as-prepared products were characterized by XRD, and TEM. The XRD results revealed that the products have neglectable change in crystal with or without Ag, but obvious change in shape and intensity with different hydrothermal process time and optimal time is 12 h at 180 C. The TEM results shown that 7 h was chose as optimal hydrothermal process time. Rhodamine (RhB) and Light Green SF Yellowish (Light green) were chose as objects to evaluate the photocatalytic activities of the products under different light irradiation. The results showed that Ag loading greatly improved the photocatalytic activity of Bi2WO6. Meanwhile, the source of light is a very important affected factor for the photocatalyst degradation, ultraviolet light has the best efficiency, but visible light was chose as the light source finally due to conservation of energy and efficiency. The dynamic behavior of Ag-loaded Bi2WO6 photocatalyst degradation of two pigments obeys pseudo-first-order kinetics at 298 K. The as-synthesized photocatalysts are stable for degradation of two pigments and can be easily recycled.
Abstract: For powering various micro/nanodevices and systems, it is necessary to develop a thin film micro-battery with high capacity and outstanding cycle performance. By using radio frequency (RF) magnetrons sputtering, tin oxide thin films used for thin film micro-batteries negative electrode were deposited on silicon substrates. Besides, doping metal impurity Cu was used to improve the performance of the films. The results showed that with the increasing of Cu-doping content, the phase of thin oxide thin films tended from crystalline to amorphous, the capacity of SnOx films increased, and the cycle performance improved. Lastly, LiCoO2/LiPON/SnOx and LiCoO2/LiPON/CuySnOx all-solid-states thin film lithium-ion batteries were prepared with MEMS techniques, and the tests gave the conclusions that with the copper doping in the negative electrode, the capacity of thin film lithium-ion batteries increased, and the batteries showed better circulation property.
Abstract: Candida rugosa Lipase was immobilized on the activated nylon-6 membrane using 0.5% glutaraldehyde as cross-linking agent. The immobilized lipase had an improved temperature and pH stability and exhibited good reusability. The adsorption process followed pseudo-second order rate equation and the biosorption isotherms correlated well with the Langmuir isotherm model. Negative ΔG indicated the adsorption process was spontaneous and the positive of ΔH indicated that the adsorption was endothermic.