Advanced Materials Research Vol. 486

Abstract: The size-dependent elastic modulus of tungsten layers and wires is predicted according to size-dependent melting temperature model. The elastic modulus decreases with decreasing of size and the drop becomes dramatically once the size decreases below 3 and 6 nm for layers and wires, respectively. Moreover, the softening of elastic modulus for wires is nearly twice as large as that for layers when size remains the same. The accuracy of the model is verified by experimental and atomistic simulations results.

Abstract: Basing on the experimental results, obtained while studying both structural and gas sensing properties of the SnO2 and In2O3 films deposited by spray pyrolysis method, it was analyzed the influence of the crystallites size on the response of the SnO2-and In2O3-based thin film gas sensors. It was confirmed that that the grain size is one of the most important parameters of metal oxides, controlling almost all operating characteristics of the solid state gas sensors. However, it was shown that the decrease of the grain size is not a universal decision contributing to the improvement of sensor response. The decrease of the grain size could be accompanied either by the improvement, or the worsening of gas sensor operating characteristics.

Abstract: The poly (vinyl pyrrolidone) (PVP)/Cobalt Acetate Composite nanofibers were prepared by electrospinning method. Then we got Co₃O₄-activated carbon fiber (ACF) from PVP/Cobalt Acetate composite nanofibers after preoxidation, carbonation and activation. Study the effect of different adsorption conditions on the adsorption rate of low concentration SO₂. The SEM, TG-DTA, XRD, FT-IR and BET analysis methods is used to characterize. The results show that the specific surface area of Co₃O₄-ACF obtained reach 1238.5 m²/g, and it contains Co₃O₄ after carbonation. The adsorption rate can reach 69.0%, when the concentration of SO₂ is 1.0 μg/mL, adsorption temperature is 20, and adsorption time is 10 minimum.

Abstract: The indentation-quench method for investigating surface crack propagation has been studied through both experiments and model. The influential factors for surface crack propagation such as specimen thickness, thermal fatigue property, and quench temperature difference (ΔT) and one single specimen being used throughout a whole test ΔT were surveyed in this paper. Practical results were obtained for ZrB₂-20%SiC-10%AlN (ZSA) ultra-high temperature ceramic. The percentage crack growth versus ΔT curves showed stable crack growth in a relative low ΔT interval and unstable crack growth above a certain ΔT, and these regimes were sensitive to the thickness. The total stress intensity factor (K_I) combining residual stress and thermal stress considering dynamical behavior during the quenching test was calculated by a surface crack theoretical model, the result of calculation was analyzed influential factors and crack propagation .

Abstract: The Cd0.3In2S4-Zn0.7In2S4 composite photocatalyst doped with transition metal Cu2+ has been synthesized by hydrothermal method. The physical and photophysical properties of the above-prepared photocatalysts were characterized by XRD, UV-Vis, SPS, SEM and XPS. The XRD peaks of Cu2+ doped Cd0.3In2S4-Zn0.7In2S4 were almost the same as the crystal structure of Cd0.3In2S4-Zn0.7In2S4. The UV-Vis absorption edge of Cu2+ doped Cd0.3In2S4-Zn0.7In2S4 shifted monotonically to long wavelength. The photocatalytic activity of Cu2+ doped photocatalysts had been improved as a result of the enhancement of the charge separation efficiency. The results indicated that the photocatalyst of Cu2+(2wt %)-Cd0.3In2S4/Zn0.7In2S4 exhibited the highest photocatalytic activity with the rate of H2 evolution to be 1141 μmol/(h·g) under visible light irradiation.

Abstract: A series of Cr³⁺doped porous CdIn₂S₄ photocatalysts with good optical property were synthesized via a facile hydrothermal process using sodium dodecyl sulfate (SDS) as template. The above-prepared photocatalysts were characterized by XRD, field emission scanning electron microscopy (FESEM), UV-Vis diffusive reflectance spectroscopy (DRS) and XPS. The influences of Cr³⁺ doping concentration on the morphology and photocatalytic activity of CdIn₂S₄ photocatalysts were investigated. The results demonstrated that the presence of Cr³⁺ doping in the CdIn₂S₄ photocatalyst had significantly influence on the crystal structure, micro-morphology, e^--h⁺ recombination and photocatalytic activity. The photocatalytic hydrogen evolution of CdIn₂S₄ was enhanced by doping, and the highest rate of hydrogen evolution of 758.8 μmol/(h·g) over Cr³⁺(0.5%)-CdIn₂S₄ was observed.

Abstract: Porcine pancreatic lipase (PPL) was immobilized in ordered mesoporous silica materials, which were using PEG 2000 (poly (ethylene glycol)) and P123 as dual templates and synthesized via hydrothermal process. The materials were silylated by (3aminopropyl) triethoxysilane (APTES) by postsynthesis-grafting method. Samples were characterized by XRD, TEM, and BET. The results showed that the 2-dimensional hexagonal mesoscopic structure kept unchanging after modification. As compared to lipase immobilized mesoporous silica, the loading amount and hydrolization activity of lipase immobilized on aminopropyl-grafted mesoporous silica increased, respectively.

Abstract: The modification of the outer layer of Al-Si alloys doped with iron atoms was examined. The samples both were taken from automotive pistons and they also were prepared in the laboratory. In any case, they were used as basic raw materials for examination. It was found that the structure and properties of these alloys are very much dependent on the cooling rate, composition and heat treatment. The iron atoms are usually doped, in order to diminish and stabilize the thermal expansion coefficient of the alloys. However, this process makes the alloys to become harder and harder; thus leading the alloys to a degradation of their mechanical behavior at elevated temperatures. Optical Microscope observations, SEM analysis of the interactive surface layers and XRD measurements were performed on tested samples. At elevated temperatures a large homogenized zone extended to about 500 (μm) without an apparent distribution of the silicon dendrites or faceted crystals was formed. Moreover at the surface of the so called homogenized zone a layer of about 35 (μm) was formed inside of which iron atoms were migrated. This layer is mainly responsible for scuffing phenomena.

Abstract: To study the dispersion characteristic of photonic crystal, the eigen-equations matrix of the light transmitting in is gotten in plane-wave expansion method, then the dispersion curves are calculated for two dimensional air-hole-type square photonic crystal respectively. And the influence on the band structures caused by oblique incidence also is studied by change incidence angle. The results of calculations demonstrate that: For two dimensional square structure photonic crystals, the shape of the band structures of TE mode is very similar to that of TM mode, but their positions of band gaps are different, especially the first band gap of TE mode in the square structure in <11> direction is completely staggered with that of the TM mode. Moreover, we get the conclusion that the width of band gap enlarges with the increasing radius of the hole in square photonic crystal in <10> direction.

Abstract: The dynamics of a non-autonomous chaotic system with one cubic nonlinearity is studied through numerical and experimental investigations in this paper. A method for calculating Lyapunov exponents (LEs), Lyapunov dimension (LD) from time series is presented. Furthermore, some complex dynamic behaviors such as periodic, quasi-periodic motion and chaos which occurred in the system are analyzed, and a route to chaos, phase portraits, Poincare sections, bifurcation diagrams are observed. Finally, a first order differential controller for the non-autonomous system is designed. Also some dynamics such as Poincare sections, bifurcation diagrams for specific control parameter values of the controlled system are showed using numerical and experimental simulations.