Current Issue : April - June Volume : 2021 Issue Number : 2 Articles : 5 Articles
Titania nanoparticles have been prepared from the precursor compound Ti(OiPr)4 using Triton X reverse micelles with varying surfactant tail, in a matrix-free aqueous (pH 2) and in non-aqueous phase (benzyl alcohol and glacial acetic acid, solvothermal method). The importance of this work lies in the further elucidation in the synthetic methodology of preparing well-characterized nanoporous solids. Comparison of the texture characteristics and surface properties of the samples prepared from each technique, was carried out using physicochemical techniques: pXRD, ΒΕΤ/DFT/BJH, FTIR, DRUV-Vis and SEM. The results show that the use of Triton X reverse micelles with varying surfactant size results in TiO2 solids with adjustable surface characteristics in contrast to matrix-free. Specifically, samples of the latter methods present higher surface area values at lower calcination temperatures but present reduced thermal stability and control of their surface properties....
We herein evaluate the use of a chemical heat pump (CHP) for upgrading waste heat. CaCl2 was used in the system of CHP. We evaluated the heat storage and heat releasing of CHP, and confirmed the practicality from the experimental results. The reactor module employed was an aluminum plate-tube heat exchanger with corrugated fins, and the CaCl2 powder was in the form of a packed bed. Heat storage operation and heat dissipation operation are performed at the same time and supplied to the heat demand destination. At this time, an environmental heat source can be used during the heat radiation operation, and the heat output can release more heat than the heat input during heat storage. The heat discharging and charging characteristics of the reactor module were evaluated experimentally. The coefficient of performance (COP) was calculated for the heat upgrading cycle, and the heat output in the system was determined. A COP of 1.42 and output of 650 W/L, based on the heat exchanger volume, were obtained using a 600 s change time for the heat pump....
Yttria stabilized zirconia (Y-TZP) is frequently used in dental and engineering applications due to its high strength and fracture resistance. In this study, 2Y-TZP samples were manufactured from commercially available powder produced by detonation synthesis. Tests of the mechanical properties exhibited an unusual combination of both very high strength and toughness. The materials show a very weak correlation between toughness and grain size. The transformability, measurable by XRD, cannot explain the high toughness. Fractographic analysis revealed a broad transformation affected zone with secondary cracks and shear bands on the tensile side of bending bars which can be made responsible for the high toughness and non-linear stress–strain curves....
Application of geostatistical techniques when evaluating mineral deposits could reflect some geological characteristics which help through the stage of planning and production. In the present study, an attempt has been done on two phosphate deposits at Elsebaiya area on both sides of the River Nile namely: Um Tondoba mine at Elsebaiya East area and Western River Nile mine in Elsebaiya West area. Depending on the available data, statistical analysis illustrated differences in the distribution of P2O5 % and ore thickness within the studied areas. Geostatistics used to start with constructing variograms for P2O5 % and thickness for the two phosphate deposits to be used with ordinary kriging models, also constructing cross variograms between P2O5 % and thickness to be used with cokriging models where the difference in the variogram parameters reflected a specific variation for each deposit horizontally and vertically. The ordinary kriging models and cokriging models illustrated different distribution behavior through both the two kriging techniques....
In this study, novel Carbon aerogel (CA)/Co3O4/Carbon (C) composites with a double protective structure are synthesized through a solvothermal method and in-situ polymerization. The morphology and structure are characterized by X-ray diffraction, scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), and Fourier transform infrared spectroscopy (FTIR). The loading content of active anode material Co3O4 in the composite is investigated by thermogravimetry, and the electrochemical properties of the composite are characterized by electrochemical impedance spectroscopy (EIS). The SEM results show that the nano-sized spherical Co3O4 particle is adhered to the inner Carbon aerogel (CA). The HRTEM result indicates the thickness of the prepared Carbon (C) up to 40 nm. Nano- sheet is coated on the surface of the Co3O4 particle. Compared with the pure Co3O4 anode materials, the Carbon aerogel (CA)/Co3O4/Carbon (C) composites have better transport kinetics for both electron and lithium-ion in EIS testing results, which may contribute to its higher specific capacity and higher first coulomb efficiency. Due to the unique structure of the composite material with double protection against the volume expansion of Co3O4 when charged, the Carbon aerogel (CA)/Co3O4/Carbon (C) composite material exhibits better cycle stability with a discharge capacity of 1180 mAh/g after 50 cycles. Therefore, the double protection strategy is verified as an effective method to improve the electrochemical performance of transition metal oxide with carbon composite as an anode material in lithium battery....
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