Advanced Materials Research Vol. 1119

Abstract: Synthesis of 0ne dimensional (1-D) vertically aligned nanostructures of ZnO are reported to act as scaffold for conversion to or coating of other semiconducting compositions. Surface of ZnO is converted to ZnSe by anion exchange and results in formation of ZnO/ZnSe core/shell nanorods. ZnSe is further converted to CuSe by cation exchange method to fabricate ZnO/CuSe core/shell nanorods. ZnO nanorods or core/shell compositions are decorated with absorber nanoparticles of CZTSe & CIGSe for the fabrications of photoanodes of nanowire solar cells. 1-D or core/shell Nanostructures are characterized by scanning electron microscope for morphological analysis and structural confirmations are made by XRD and Raman spectroscopy.

Abstract: The study of dye-sensitized solar cells (DSCs) based on nanocrystalline films of high band gap semiconductors is a progressive field of research that is being carried out by scientists in a wide range of laboratories. To improve the conversion efficiency of the DSCs, the SnO₂ nanocrystalline is prepared via the hydrothermal methods, and characterized by XRD, TEM, BET and Absorption spectrum. Though analysis the results, the conclusion is shown the pure SnO₂ is prepared under a certain condition, such as pH=11, reaction time for 8 days, heat treating temperature at 200°C and 0.05mol/L SnCl₄ concentration, the SnO₂ nanocrystalline both shows the single phase that SnO₂ from the sule solution to kalin solution. The prepared SnO₂ nanocrystalline shows the rod shape crystalline, the diameter of rod shape crystalline is about 10nm, the length of rod shape crystalline is about 100nm, the surface area of SnO₂ nanocrystalline is 79.7591m²/g. The absorbance of SnO₂ nanocrystalline shows the strong absorption in the ultraviolet ray range, the absorbance of synthesized SnO₂ nanocrystalline shows the highest value.

Abstract: Nanoscale HZSM-5 zeolite was hydrothermally treated with ammonia water at 773K and then loaded with La₂O₃, NiO and MoO₃. The parent and modified nanoscale HZSM-5 zeolite catalysts were characterized by XRD, NH₃-TPD, Py-FTIR and N₂ adsorption. The characterization results indicated that the acid strength of the parent nanoscale HZSM-5 was weakened, the L/B acidity increased notably and the metal species were well dispersed on the surface of the supports after the combined-modification measurement. In the presence of hydrogen, the performance of the modified HZSM-5 catalyst for FCC gasoline upgrading was evaluated in a fixed bed reactor. Under the given reaction conditions, the average olefin content in FCC gasoline was decreased from 33.2 vol% to 11.3 vol% within 300 h time on stream; the aromatic and isoparaffin contents in the product were increased from 29.8 vol% and 25.9 vol% to 39.0 vol% and 35.4 vol%, respectively. The modified nanoscale HZSM-5 catalyst reduced sulfur concentration in FCC gasoline by about 90% without gasoline octane number loss.

Abstract: Based on the two distinct solutions, as classical solution for an elastic half space containing a circular hole at nanoscale, the complex variable and superposition method was proposed and employed to investigate the state of stress and displacement in an half space with surface tension for nanoelastic material.The results indicate some characteristics in half space which are different from those in classical elasticity theory .

Abstract: Friction is a fundamental phenomenon in tribology involving complex mechanisms between the contacting surfaces. Measurements of friction are often made using devices with substantially larger contact area than dimensions corresponding to microstructural features of the materials. Hence, for multi-phase materials, influence of particular microstructural constituents is not resolved. In the present work, a tribometer with a contact area in the nanoscale range was used to map friction for different types of tool steels with different chemical-and phase composition. Owing to the small tip radius, frictional characteristics of primary carbides and the steel matrix were measured and compared. Depending on chemical composition, a difference was observed where the coefficient of friction was approximately twice higher for the steel possessing highest coefficient of friction, including both carbides and the steel matrix.

Abstract: This work presents a study on the effect of Minimum Quantity Lubricant of Al203 nanoparticle with Sodium Dodecylbenzene Sulfonate, SDBS on surface roughness during turning of Mild Steel under constant machining parameters. Surfactant, SDBS in the nanolubricant creates stability of the particles in the base fluid. The experiments were conducted under dry, MQL with pure nanolubricant, and MQL with nanolubricant and additional SDBS. The experimental results showed that MQL nanolubricant with additional SDBS improves the surface roughness compared to dry cutting.

Abstract: Biopolymer composites are required to enhance their mechanical properties and heat resistance for the industrial applications. Especially, the addition of nanoparticles in biopolymers can give various functionalities such as electrical, thermal and mechanical properties. In this study, the nanoparticles having functional characteristics were used to enhance heat resistance, tensile properties, and electrical conductivity of PBTG biofilms. Changes in tensile, crystalline and thermal properties of PBTG films with different additives (carbon black, sepiolite, zinc oxide, MWCNT) were investigated by the tensile tester and the instrument of XRD, DSC and TGA. As the results, Electrical conductivity of the biofilms was improved up to 10^-5S/cm by adding MWCNT. And tensile modulus of PBTG biofilms with MWCNT was 1.37 times higher than the pure PBTG film. But their heat-resistance characteristics were not significantly affected by adding nanoparticles.

Abstract: Based on nonlocal beam theories, the dynamic mechanical behavior of a clamped-free Timoshenko nano-beam subjected to a variable speed moving force are studied in this paper. The analytical solution of differential equation is obtained using state-space method. The effects of the nonlocal stress and the magnitude of the moving force acceleration on the dynamic responses of the nano-beam are discussed in detail. The results indicate that nonlocal effects and moving force acceleration play a significant role on the dynamic mechanical response of nano-beam.

Abstract: Enhanced oil recovery (EOR) can extend the life of an oil field by providing additional drive mechanism to the crude oil. The use of carbon dioxide (CO₂) in EOR application has shown a good potential, but it has some weaknesses such as viscous fingering. Viscous fingering problem can be solved by reducing the CO₂ gas mobility, which can be achieved by transforming the CO₂ gas into surfactant-stabilized foam. However, surfactant-stabilized foam is not very stable under harsh reservoir condition, which could be handled by introducing nanoparticle-stabilized CO₂ foam. Thus, this paper aims to investigate the mobility of nanoparticle-stabilized CO₂ foam at varying brine salinity (1 - 4 wt%), concentration of AOS surfactant (0.01 - 1 wt%) and concentration of nanoparticle (0.05 - 1 wt%). The volumetric phase ratio was fixed at 8 CO₂/aqueous. The sand pack foam flooding test was conducted to measure the effectiveness of the formulated foam to displace the oil inside the porous medium through mobility and oil recovery measurement. It was found that foam mobility is inversely proportional to oil recovery. Mobility decreased when increase of brine salinity, surfactant and nanoparticle concentration, which has increased the oil recovery. Thus, it is important to reduce the foam mobility for efficient displacement process, which could minimize viscous fingering and enhance the oil recovery. This could be achieved by increasing the viscosity of displacing fluid (foam) for more stable displacement in EOR application.

Abstract: Zinc aluminate (ZnAl₂O₄) and zinc ferrite (ZnFe₂O₄) nanocrystalline structures dispersed into SiO₂ matrix were prepared by sol-gel method. Phase formation of ZnAl₂O₄ and ZnFe₂O₄ was confirmed by X-ray diffraction (XRD) analysis. The crystallite sizes was determine using Scherer’s equation from the broadening of dominant peak at (311) plane. It was found the crystallite size of both compound decreased due to the decrement compositions of Zn²⁺ ion and Al³⁺ / Fe³⁺ ions. The crystallite sizes for ZnAl₂O₄ and ZnFe₂O₄ was calculated to be around ~ 14.16 – 11.27 nm and ~ 11.27 – 4.72 nm, respectively. FTIR analysis was done to determine the formation of spinel structures. FTIR results analysis confirmed that the formation of spinel structure where it has been observed that the bands around 800 cm^-1 was associated to the vibrations of aluminum-oxygen and metal-oxygen-aluminum bonds. This characteristic was identified to the formation of zinc aluminate spinel structure. The optical properties have been done to determine the energy bandgap of ZnAl₂O₄ and ZnFe₂O₄ samples. The Uv-Visible absorption spectra have been done within wavelength 300 – 800 nm and the graph was plotted into the Tauc plot. This new dielectric material was purposed to improve the value of dielectric permittivity with addition of SiO₂ where it can be applied as microwave dielectric material without changing the original spinel structures.