Hyperfine interactions in (CuFe2O4)1 − x (SnO2) x (x = 0, 1, 5, 10 and 20 wt.%) nanocomposites studied by Mössbauer spectroscopy

A series of (CuFe₂O₄)_1???x (SnO₂) _x nanocomposites (x = 0, 1, 5, 10, 20 wt.%) have been prepared by urea–nitrate combustion method. The room temperature Mössbauer spectra of CuFe₂O₄ and (CuFe₂O₄)_0.99(SnO₂)_0.01 contained two sextets while remaining samples contained at least four sextets with additional doublet indicating the presence of paramagnetic phase. The variations of isomer shift, quadruple splitting and magnetic hyperfine field values were found with the addition of SnO₂.     

Semiconductor laser crystallization of a-Si:H on conducting tin-oxide-coated glass for solar cell and display applications

Semiconductor laser (=805 nm) crystallization of hydrogenated amorphous silicon (a-Si:H) deposited on a low-cost fluoride-doped tin-oxide-coated glass substrate is demonstrated. X-ray diffraction confirms that the structure of the polycrystalline silicon thus formed shows (111), (220), and (311) peaks. A sharp Raman peak at 520 cm^-1 further confirms the crystallization. Atomic force microscope images of a Secco-etched laser-treated sample reveal the granular structure of the poly-Si. Grains as big as 10 times the film thickness are readily obtained and sample as thick as 5000 Å is easily crystallized. The method can be extended to films with a thickness of several microns. PACS 42.55.Px; 42.62.Cf; 81.05.Gc     

Ultrafast all-optical demultiplexer based on monolithic Mach–Zehnder interferometer with integrated semiconductor optical amplifiers

A monolithically integrated and fully packaged Mach–Zehnder interferometer with semiconductor optical amplifiers (MZI-SOA) is demonstrated as polarisation-independent high-speed demultiplexer for up to 160 Gbit/s optical time division multiplexed (OTDM) data streams.     

Modelling of the plasma-substrate interaction and prediction of substrate temperature during the plasma heating

Temperature of the substrate during plasma heating and spraying plays an important role on quality of the substrate and coating. In this study a three dimensional numerical model is developed to simulate the Ar-N₂ plasma jet and conjugate heat transfer between plasma and substrate. The influencing of operating parameters on thermal flux from the plasma to the substrate and substrate temperature are discussed. Transient simulations are carried out to predict the substrate temperature with heating time. The arc current, gas flow rate, stand-off distance, substrate material and environment around the substrate significantly affect the thermal flux to the substrate. Heat flux to the substrate cannot be neglected in the coating built-up models. Present model is validated by comparing the results of present model with previous predictions and measurements.     

Synthesis and Characterization of Rare Earth Orthovanadate (RVO4; R = La, Ce, Nd, Sm, Eu & Gd) Nanorods/Nanocrystals/Nanospindles by a Facile Sonochemical Method and Their Catalytic Properties

We report herein on an efficient sonochemical method for the synthesis of rare earth orthovanadate nanorods/nanoparticles/nanospindles, (general formula RVO₄; R = La, Ce, Nd, Sm, Eu and Gd). TGA, XRD, FTIR, Raman, UV–Vis, and TEM studies are employed for their characterization and for understanding their morphologies. In order to vary the textural properties of the rare earth vanadates, two surfactants, polyethylene glycol (PEG) and amphiphilic triblock copolymer Pluronic P123, are chosen in the preparation. While the sonochemical synthesis in the presence of PEG results in the formation of nearly spherical nanoparticles of LaVO₄, CeVO₄, SmVO₄ and EuVO₄, the same technique yields nanorods and nanospindles of NdVO₄ and GdVO₄, respectively. When P123 is used as the surfactant, the morphologies of RVO₄ are strikingly different, and in most cases nanorods and nanospindles are formed. The photocatalytic activities of the rare earth orthovanadate have been evaluated by studying the degradation of methylene blue, and CeVO₄ seems to be the best catalyst in the heterogeneous photolysis. The electrocatalytic activity of the vanadates has been examined by studying the hydrogen evolution reaction using a linear sweep voltammogram technique in 1 M of a H₂SO₄ solution. GdVO₄ seems to be the best electrocatalyst. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Ionic liquid modified silica gel for the sorption of americium(III) and europium(III) from dilute nitric acid medium

The imidazolium bis(2-ethylhexyl) phosphate moiety was chemically attached on silica gel by chemical modification. The resulting product ([SG-Im]⁺ [DEHP]^?) was characterized by FT-IR spectroscopy, thermogravimetry and elemental analysis. The sorption behavior of Am(III) and Eu(III) on [SG-Im]⁺ [DEHP]^? was studied from dilute nitric acid medium for the separation of Am(III) and Eu(III) from aqueous waste. The effect of time, concentrations of nitric acid and europium in aqueous phase on the distribution coefficient (K _d) was studied. The study indicated the possibility of using modified silica for the separation of Eu(III) from Am(III) with high separation factors (>50 at 0.1 M HNO₃).     

Effect of external pressure on Tc of as‐grown and thermally treated superconducting Rbx Fe2–ySe2 single crystals

We report on the effect of external pressure on the superconducting transition temperature (T_c) of as‐grown and thermally treated single crystals of superconducting iron chalcogenide Rb_0.85Fe_1.9Se₂. The superconducting transition temperature of 27.1 K at ambient pressure for the as‐grown sample was found to increase up to 33.2 K for the sample annealed for 3 h at 215 °C in vacuum. An increase of T_c up to 28.2 K was observed for the as‐grown sample at a pressure of 0.83 GPa. For all the studied crystals, annealed in the temperature range between 215 °C and 290 °C, the external pressure seems to decrease the superconducting transition temperature and a negative pressure coefficient of T_c was observed. (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

A decision support system for selection of tractor-implement system used on Indian farms

The selection of tractor and its matching implements has now become very difficult in India because of availability of variety of tractor models ranging from 10 to 45 kW. To overcome the problem of matching of tractor-implement system, an expert system modelling approach leading to decision support system (DSS) was adopted to make the step wise decision. The application of DSS was demonstrated in the paper to select either an implement to match the tractor or to select a tractor to match the implement under different soil and operating conditions. The DSS leading to computer software developed in Visual Basic™ programming provided the intuitive user interfaces by linking databases such as specifications of tractors and implements, tractor performance data, soil and operating conditions, to support the decision on selection of tractor-implement system. The programme calculates working width of implement based on input data for the most critical field operation and helps in selection of a suitable implement having width nearer to the calculated value among the commercially available implements. The software calculates the required drawbar power of the tractor based on draft and working speed of the selected implement. Finally, the PTO power requirement of a tractor is calculated by the software. Based on calculated PTO power, the software suggests available makes and models of tractor/machinery from the compiled data bank. The developed DSS was tested with a case study to demonstrate the flexibility of the software. The DSS can be used effectively in selection of a tractor or an implement of particular size from various makes and models of commercially available tractors and implements.