Key Engineering Materials Vols. 353-358

Abstract: Removed due to plagiarism. The original paper was published as http://onlinelibrary.wiley.com/doi/10.1002/1521-3765%2820001117%296:22%3C4082::AID-CHEM4082%3E3.0.CO;2-S/abstract

Abstract: Ultrafine TiO2 powders as rutile and anatase phase were simply precipitated at room temperature for only tens of hours by simply controlling the pH value and Ti4+ concentration via aqueous TiCl4 solution. Under the optimal pH value and Ti4+ concentration, the average particle size of powders with rutile phase was 3.7nm, while that of powders with anatase phase was 3.0nm. The average particle size was calculated from the broadening of corresponding X-ray spectral peaks by Scherrer formula. In addition, 3.0 mol.l-1 are suggested to be used as concentration of stock solutions instead of the current concentration 2.0 mol.l-1.

Abstract: large-scale and elegant one-dimension tubular nanostructure TaS2, have been generated successfully employing solid-phase reaction growth with tantalum and sulfur powders. Detailed experimental procedures, and the characterization of associated product, have been evaluated using transmission electron microscopy (TEM) and other techniques. The results show that the reaction yielded a lot of one dimension nanostructures of TaS2 with average diameter of one hundred nanometers and length of several micrometers (or several ten micrometers). Moreover, effect of TaS2 nanostructure, as additive in commercial lubricating oil T40, was initially measured by UMT Multi-specimen Test System (UMT-2). The results show, as additive, antiwear and bearing weight ability of 1-D TaS2 nanostructure, excelled ordinary lubricating oil at atmosphere.

Abstract: Constant current plus pulse current electrical sintering was introduced into the sintering of a ball-milled nanocrystalline Fe-2Cu-2Ni-1Mo-0.8C mixed powder. Effect of pulse current charging time on the properties of sintered products was studied. Constant electric current sintering was also used for comparison. A nanostructured iron-based material was obtained within 4 minutes of sintering. It has a density of 7.7 g/cm3 (relative density of 98.7 %) with an average grain size (iron-matrix) of 58 nm and carbide particle size of less than 100 nm, a hardness of HRC 64 and transverse rupture strength of 2004 MPa. When only pulsed electric current sintering was used with a sintering time of 5 min, a fine grained iron-base material with density of 7.74 g/cm3 (relative density of 99.2%), a hardness of HRC 65 and transverse rupture strength of 2045 MPa was obtained.

Abstract: The chitosan scaffold we prepared have a high porosity of about 90% with pore sizes from 50 to 200m. Lactose was conjugated onto the inner surface of the highly porous chitosan scaffold. It was used as substrate for rat hepatocytes culture. The cell attachment ratio was much higher than on monolayer membrane and non-modified porous scaffold. Metabolic activities of the cells were evaluated in terms of albumin secretion and urea synthesis. It was found that hepatocytes cultured on the modified scaffolds showed an increase in albumin secretion during the first 4 days and were more stable than that on non-modified scaffold. The results showed that the microstructure of porous scaffolds provides large surface for cells to adhere and facilitates nutrient and oxygen transportation. Such lactose modified scaffold has a potential application in bioartificial liver support system.

Abstract: On the basis of the Landau-Ginzburg models established by Falk and other authors, a new model for martensitic transformation in nanograined powder is developed, in which the influence of the interface on martensitic transformation in nanograined powder is considered. The interface strain coefficient K, the factor describing the difference of the strain between the interface and the core of a nano-grain, was suggested in this paper. The equation in the present model was solved numerically, and the size effect was observed. The calculation results show that the critical size increases with the drop in temperature, which means that the lower temperature will promote martensitic transformation in nanograined materials.

Abstract: In order to prolong the service life of Aluminum alloy die casting dies, different surface treatments were adopted to avoid melting loss on the surface of the dies. In this paper, the dynamic melting-loss properties of H13 steel were compared among non-treatment, vapor oxidation treating, carbonitriding and composite treatment of nitirding and vapor oxidation in liquid aluminum of ADC12 at 700 °C by the weight loss method. The surface structures of the specimens after treatments were analyzed by the optical microscopy (OP); the patterns of specimens on the surface were observed by measuring microscope and the melting-loss characteristics of specimens with different treatment were analyzed. The results showed that the melting-loss property was heightened obviously by different surface treatments; especially the melting-loss property of the specimens with composite treatment of nitirding and vapor oxidation was the best.

Abstract: Protein expression of growth factors involved in fracture healing and osteoporosis were investigated in ovariectomised (OVX) rat fracture model using histological and immunohistochemical analysis. The OVX model was confirmed by a significantly increased body weight and reduced bone density of the non-fracture hind limbs. The tissue morphology and the protein expression were assessed on the paraffin sections of the fracture callus at day 7, 14, 28 and 42 after fracture. Histology revealed a significantly higher ratio of fibrous tissue over bone or cartilage over bone in the fracture callus at day 28 and 42 in the OVX rats than in the normal rats. Immunohistochemical staining of IGF-I, IGF-IRα, MMP-1, TIMP-1 and 2 showed a different pattern between the OVX and the control groups. A down-regulation of IGF-I and TIMP-1 and an up-regulation of MMP-1 were observed in OVX rats, which may account in part for the delayed healing of the osteoporotic fracture and may affect extracellular matrix composition, an important determinant of callus strength.

Abstract: Nanocubes, monodispersed nanocrystals and nanospheres of Au have been prepared by a simple reaction between HAuCl4·4H2O, NaOH and NH2OH·HCl in the presence of gelatin. The role of gelatin and the affection of pH in producing the nanoparticles of Au were discussed. The products were characterized by X-ray powder diffraction, transmission electron microscopy, and UV-visible absorption spectroscopy. The sizes of the monodispersed nanocrystals of Au were estimated by Debye-Scherrer formula according to XRD spectrum.

Abstract: Epoxy-organoclay nanocomposite were prepared and investigated in terms of mechanical properties and also in term of water diffusion and sulfuric acid corrosion resistance. Diffusion was studied through epoxy samples containing up to 6phr of organically treated montmorillonite. The diffusion of the environmental solution was measured by immersion of the samples in these solutions at elevated temperature with noting the increase in weight as immersion function of time. An evaluation by flexural strength of the nanoclay/epoxy composites samples was made to compare their mechanical performances under corrosive environment as a function of immersion time and temperature.