Applied Mechanics and Materials Vols. 182-183

Abstract: Methanotrophic physiology is strongly affected by the amount of bioavailable copper, which regulates the enzymes used by methanotrophs to oxidize methane. Methanobactin is a small peptide secreted by methanotrophic bacteria that binds copper outside of the bacterial cell. In this study, gold nanoparticles were firstly synthesized with citrate acid, followed by addition of methanobactin. Then as CuSO₄ was continuously added to the solution, we found a red shift in the Uv-vis absorption spectra. Meanwhile, for the mixture of methanobactin, 1,4-resorcinol and chlorauric acid, we also found an absorption at 540nm after 1h in dark. We presume that methanobactin has the bioactivity of protecting gold nanoparticles as well as delivering electron for the catalytic synthesis of gold nanoparticles. These molecules then go on to form gold nanoparticles. Gold nanoparticles can be seen with the naked eye, as they turn a gold solution from yellow/gold to a deep cranberry/red. The nanoparticles also display a characteristic absorbance of approximately 540 nm on absorption spectra.

Abstract: PMMA/MMT nanocomposites has been prepared by using methyl methacrylate (MMA), montmorillonite (MMT) and ethanolamine as the raw materials via an in-situ free radical polymerization process. The as-prepared nanocomposites were characterized by Fourier transformation infrared spectroscopy (FTIR), X-ray diffraction (XRD) and thermogravimetric analysis (TGA). The results show that the poly(methyl methacrylate) and inorganic montmorillonite have been effectively combined. The structure and thermal stability of the as-prepared nanocomposites are different from the content of MMT in the nanacomposites.

Abstract: Cellulose/Ag/polyaniline conductive composite with rather excellent electrical conductivity was heterogeneously synthesized in this paper. The UV-Vis analysis indicated that homogeneous nanoAg particles deposited on the surface of cellulose in the form of globe particles. They offered some electrons to polyaniline chains. This behavior resulted to the facts that more polyaniline embedded on cellulose and an integrated electrically conductive network formed. Consequently, the high electrical conductivity of the composite was observed. The value was 3.48 S/cm, which was higher two magnitudes than the electrical conductivity of cellulose/polyaniline composite (2.15×10^-2 S/cm), and even was higher than the electrical conductivity of pure polyaniline (0.142 S/cm). This paper provided a facile method for the preparation of cellulose/Ag/ polyaniline composite with favorable electrical conductivity.

Abstract: In this study polypropylene (PP) composites containing β-nucleating agent (NT-C) and talc filler were prepared by melt compounding. The melting and crystallization behavior, morphology and mechanical properties of the composites were studied by means of differential scanning calorimetry (DSC), wide angle X-ray diffraction (WAXD), polarized light microscopy (PLM) and mechanical tests. The results indicate that talc suppresses the formation of β phase, but promotes the formation of α phase. The Izod notched impact strength and tensile strength of β-PP/talc composites are superior to those of PP/talc composites, indicating an outstanding balance of stiffness and toughness of β-PP/talc composites.

Abstract: A facile method to selectively synthesize nano-scaled Gd₂O₃ with different morphology such as nanosheres and nanorods has been developed in our report. The precursors GdOHCO₃ can be prepared by a two-step hydrothermal process via homogeneous generation of hydroxide ions through the hydrolysis of urea, and the formation of different morphology structures were obtained under different reaction temperatures. After further heating treatment, a transformation from GdOHCO₃ to cubic Gd₂O₃ takes place. The morphology and size of nano Gd₂O₃ strongly depend on that of the precursors GdOHCO₃. The X-ray diffraction, transmission electron microscopy and scanning electron microscopy were employed to characterize the as-obtained low-dimensional nanostructures. And the effects of hydrothermal temperature, solvent and urea concentration on the morphologies of the products were also studied.

Abstract: the properties of the alumina ceramics depends directly on the ceramic slurry performance, effects of slurry polymerization of many factors, mainly including the slurry pH value, temperature, initiator. This paper focuses on the study of the factors affecting the performance of slurry, received a specific parameter values, so as to prepare the blank has high strength over 78MPa, density distribution and contraction of uniform body.

Abstract: Wood flour is inexpensive, and can be used as a reinforcing agent to improve the mechanical properties of high density polyethylene, reduce cost. Wood fiber as a renewable natural material, biodegradation, therefore, high filling wood powder high density polyethylene composite material with certain environmental compatibility, at the same time, high density polyethylene can be a source of waste recycling materials, therefore plastic-wood composite material is a kind of can reduce the "white pollution" environmental material. [1-5]

Abstract: A high performance water resistance agent KD-3 prepared from OPC cement, fly ash, slag and additives was used for the modification of hemi-hydrate desulphurization gypsum. Various factors on gypsum block were investigated. The prepared gypsum block possesses excellent water-resistance, good operating property and high mechanical strength. The optimized results was obtained: calcined gypsum 74.9%, KD-3 25%, retarder 0.1%, curing temperature 60°C and curing time 16h.

Abstract: In penetration mechanics, the material parameters of the rod penetrator are very important factors which influence the effect of penetration. The effect of each parameter changes with the impact velocity. Simulation analysis of two models filled with tungsten alloy and tungsten carbide separately penetrating semi-infinite armor steel target at medium to high velocities has been made to quantitatively analyze the key roles that the density and hardness play. Simulation results indicate that a dividing line of velocity exists between the penetrations of two materials. Above the line, tungsten alloy rod with greater density has a distinct advantage with increasing velocity. Below the line, the advantage of tungsten carbide rod with greater hardness is significantly more with the decreasing velocity. In the process of penetration, penetration velocity decreases rapidly from a high value to zero. The simulation result provides quantitative analytic basis which can be used to prove that the penetrator composed of two different materials is better than the one composed of homogenous material.

Abstract: The mechanism of formation of the large-dimension rare-earth(RE) inclusions in steels is discussed by TEM(Transmission Electron Microscope) taking steel 5CrNiMo with addition of RE as example. The two or several large-dimension RE inclusions come out independent nucleation which grow up into a 0.3~0.5 micron in length, then attract and integrate into the large-dimension with 1~5 micron in length. Though the dimension difference between the RE inclusions is varied, the shape is spherical or approximate spherical or elliptical, but no sharply corneous, because RE can promote the inclusion shape variation through metamorphism.