Plasma effects in semiconducting nanowire growth

Three case studies are presented to show low-temperature plasma-specific effects in the solution of (i) effective control of nucleation and growth; (ii) environmental friendliness; and (iii) energy efficiency critical issues in semiconducting nanowire growth. The first case (related to (i) and (iii)) shows that in catalytic growth of Si nanowires, plasma-specific effects lead to a substantial increase in growth rates, decrease of the minimum nanowire thickness, and much faster nanowire nucleation at the same growth temperatures. For nucleation and growth of nanowires of the same thickness, much lower temperatures are required. In the second example (related to (ii)), we produce Si nanowire networks with controllable nanowire thickness, length, and area density without any catalyst or external supply of Si building material. This case is an environmentally-friendly alternative to the commonly used Si microfabrication based on a highly-toxic silane precursor gas. The third example is related to (iii) and demonstrates that ZnO nanowires can be synthesized in plasma-enhanced CVD at significantly lower process temperatures than in similar neutral gas-based processes and without compromising structural quality and performance of the nanowires. Our results are relevant to the development of next-generation nanoelectronic, optoelectronic, energy conversion and sensing devices based on semiconducting nanowires.     

The corrosion of INCONEL alloy 740 in simulated environments for pulverized coal-fired boiler

The corrosion of a new nickel base superalloy, INCONEL alloy 740, has been studied at 550 and 700 °C on exposure to the synthetic coal ash/flue gas environments by means of XRD, SEM, and EDX. Low temperature hot corrosion of the new alloy occurred at two temperatures. The corrosion started to form the thin Cr₂O₃ scale on the alloy at 550 °C and developed as pitting attack resulted from sulfidation. The frontal attack at 700 °C consisted of two successive stages in which the corrosion mechanism started from the sulfidation and ended up in the fluxing of oxide. The compact and protective Cr₂O₃ scale formed and the internal sulfidation took place during the initial stage. The severe hot corrosion occurred due to the presence of the molten CoSO₄ during the propagation stage. The loose and porous outer layer and the compact inner layer consisted of spinels and oxides, respectively. The sulfides of Cr, Ti, and Nb formed on the front of oxide scale and in Cr-depletion zone. The rapid degradation of corrosion resistance of the alloy can be attributed to the dissolution of both cobalt and cobalt oxide on the surface. The alloy of 25% Cr exhibited better resistance to coal ash/flue gas corrosion as compared to the alloy of 23% Cr in the present case.     

Comparison of appearance,microstructure and tensile properties during friction stir welding processes of Al–Si alloys

The scope of this paper is to evaluate and discuss the flow phenomena of Al–2Si and Al–12Si alloys, which were joined through friction stir welding processes. The feed rate of 50mm/min and tool rotation of 600, 900, and 1200 rpm were selected for the processes. There was much change in the surface morphology with smoothness for Al–2Si alloy and roughness for Al–12 Si alloys. The microstructure studies on the weld zone were performed. The mechanical properties like tensile strength and hardness are discussed in detail.     

石膏板干墙系统与建筑防火

<正>轻钢龙骨石膏板隔墙和吊顶系统,统称石膏板干墙系统,凭借着其安装快速简便、可灵活造型、轻质、美观等特性已成为室内装修不可缺少的系统。其实,干墙系统除了这些优秀的装饰特性外还具备很强的建筑构件必备的保温隔热、隔声、吸声和防火等功能。     

Wild Brazilian Mustard (Brassica juncea L.) Seed Oil Methyl Esters as Biodiesel Fuel

Wild mustard (Brassica juncea L.) oil is evaluated as a feedstock for biodiesel production. Biodiesel was obtained in 94 wt.% yield by a standard transesterification procedure with methanol and sodium methoxide catalyst. Wild mustard oil had a high content of erucic (13(Z)-docosenoic; 45.7 wt.%) acid, with linoleic (9(Z),12(Z)-octadecadienoic; 14.2 wt.%) and linolenic (9(Z),12(Z),15(Z)-octadecatrienoic; 13.0 wt.%) acids comprising most of the remaining fatty acid profile. The cetane number, kinematic viscosity, and oxidative stability (Rancimat method) of the methyl esters was 61.1, 5.33 mm² s⁻¹ (40 °C) and 4.8 h (110 °C), respectively. The cloud, pour and cold filter plugging points were 4, −21 and −3 °C, respectively. Other properties such as acid value, lubricity, free and total glycerol content, iodine value, Gardner color, specific gravity, as well as sulfur and phosphorous contents were also determined and are discussed in light of biodiesel standards ASTM D6751 and EN 14214. Also reported are the properties and composition of wild mustard oil, along with identification of wild mustard collected in Brazil as Brassica juncea L. (2n = 36) as opposed to the currently accepted Sinapis arvensis L. (2n = 18) classification. In summary, wild mustard oil appears to be an acceptable feedstock for biodiesel production. Disclaimer: Product names are necessary to report factually on available data; however, the USDA neither guarantees nor warrants the standard of the product, and the use of the name by USDA implies no approval of the product to the exclusion of others that may also be suitable.     

Emulsification of Indian heavy crude oil using a novel surfactant for pipeline transportation

The most economical way to overcome flow assurance problems associated with transportation of heavy crude oil through offshore pipelines is by emulsifying it with water in the presence of a suitable surfactant.In this research,a novel surfactant,tri-triethanolamine monosunflower ester,was synthesized in the laboratory by extracting fatty acids present in sunflower(Helianthus annuus)oil.Synthesized surfactant was used to prepare oil-in-water emulsions of a heavy crude oil from the western oil field of India.After emulsification,a dramatic decrease in pour point as well as viscosity was observed.All the prepared emulsions were found to be flowing even at 1°C.The emulsion developed with 60%oil content and 2wt%surfactant showed a decrease in viscosity of 96%.The stability of the emulsion was investigated at different temperatures,and it was found to be highly stable.The effectiveness of surfactant in emulsifying the heavy oil in water was investigated by measuring the equilibrium interfacial tension(IFT)between the crude oil(diluted)and the aqueous phase along with zeta potential of emulsions.2wt%surfactant decreased IFT by almost nine times that of no surfactant.These results suggested that the synthesized surfactant may be used to prepare a stable oil-in-water emulsion for its transportation through offshore pipelines efficiently.     

Comparison of photostability, optical and structural properties of TiO2/conjugated polymer hybrid composites prepared via different methods

In this work, we have synthesized high quality TiO₂ nanocrystallites by sol-gel method (TiO₂ white (w)) and compared its properties with the ones synthesized by the simple hydrolysis method in aqueous solution (TiO₂ transparent (t)). The TiO₂/MEH-PPV nanocomposites are formed mainly by two ways: (i) Prepared in the form of the colloidal solution by adding the known concentration of the TiO₂ in MEH-PPV and then sonicate it well; (ii) In the thin film form by depositing the above solution over a glass substrate by spin coating. The properties of the resulting dispersions could be tailored by varying the composition and concentration of TiO₂ nanoparticles in CP's. The TiO₂ nanoparticles prepared by both methods show anatase character of TiO₂ as elucidated by X-ray diffraction (XRD) studies. Transmission electron microscopic (TEM) studies reveal that the transparent colloidal suspension of TiO₂ exhibits agglomeration of TiO₂ nanoparticles (size ~ 150-300 nm) and this trend is maintained in the MEH-PPV matrix for TiO₂/MEH-PPV composites as well. However, the composite obtained by mixing MEH-PPV with sol-gel prepared TiO₂(w) shows uniform nanoscale dispersion of TiO₂ (size ~ 20 nm) in MEH-PPV matrix. The UV-VIS absorption, photoluminescence (PL) and lifetime studies confirm the presence of dynamic quenching effect indicating efficient photoinduced charge transfer in TiO₂/MEH-PPV hybrid composites particularly with white TiO₂. It is conjectured that the devices containing TiO₂/MEH-PPV composites for TiO₂ prepared by the sol-gel method should lead to significant improvement in the photovoltaic performance of TiO₂/MEH-PPV hybrid solar cells.     

Nanoscaffold matrices for size-controlled, pulsatile transdermal testosterone delivery: nanosize effects on the time dimension

Pulsatile transdermal testosterone (T) has applications in hormone supplementation and male contraception. Pulsatile T delivery was achieved by assembling crystalline and nanoparticulate T in nucleation-inhibiting polymer matrices of controlled porosity. Different interference patterns observed from various polymeric films containing T were due to the various particle sizes of T present in the polymer matrices. Scanning electron microscopy was used to determine the size and shape of T crystals. Skin-adherent films containing T nanoparticles of any size between 10-500?nm could be prepared using pharmaceutically acceptable vinylic polymers. Drug release and skin permeation profiles were studied. The dissolution-diffusion behavior of nanoparticles differed from crystalline and molecular states. Nanosize may thus be used to engineer chronopharmacologically relevant drug delivery.     

Porochemothermoelastic Solution for an Inclined Borehole in a Transversely Isotropic Formation

A generalized anisotropic poromechanics formulation for chemically active poroelastic media under nonisothermal conditions, termed as porochemothermoelastic, is presented. The pore fluid is modeled as a two-species constituent comprised of the solute and the solvent. Governing equations are developed and applied to obtain the analytical solution for an inclined borehole in chemically active transversely isotropic formation subjected to a three-dimensional state of stress and nonisothermal conditions. Numerical examples are presented to demonstrate the thermochemical effects on stress and pore pressure distributions in the vicinity of the borehole and their potential impacts on borehole stability.     

A novel method for vehicle detection in high-resolution aerial remote sensing images using YOLT approach

Multimedia Tools and Applications - Owing to the innovative challenge stood by an intergovernmental military alliance, we have proposed a model to find novel solutions in the areas of data...