Growth and characterization of Ni:DLC composite films using pulsed laser deposition technique

The structure and surface morphology of Ni-incorporated diamond like carbon (Ni:DLC) films have been investigated. These films were deposited on Si substrates using pulsed laser deposition (PLD) technique. A KrF Excimer laser (λ = 248 nm) was used for co-ablation from multi component Ni–graphite target. The concentration of Ni was varied by ablating the Ni part of the target with various numbers of laser pulses. The SEM and AFM analysis reveals that the surface is composed of segregates of Ni which increases with the increase in Ni content during the growth process. The structural investigations by XRD and Raman spectroscopy provided information about the orientation of the incorporated constituent and the ordering of the carbon species. Maximum height of the nano structures which were observed on the surface was ∼50 nm. The G-peak of the graphite was shifted towards higher wave number due to enhancement in SP² sites which have been increased due to the increase in the Ni concentration. A small change in the surface roughness ranging from 7.78 nm to 13.1 nm due to increased Ni concentration was also observed.     

pH-dependant structural and morphology evolution of Ni(OH)2 nanostructures and their morphology retention upon thermal annealing to NiO

Nickel hydroxide nanosheets, nanobelts and nanorods were prepared by hydrothermal treatment of the precipitates obtained at different pH values. The morphology and crystal structure of the products could be controlled simply by adjusting the pH value at precipitation. Interconnected nanosheets of hexagonal β-Ni(OH)₂ with thickness around 10–20 nm were formed at pH ∼ 11, whereas nanobelts with typical widths around 40–80 nm, and nanorods with diameters around 50–60 nm of phase pure α-Ni(OH)₂ containing intercalated sulphate ions were obtained in the pH range ∼9.5–8.5. Thermal annealing of the hydroxides at 500 °C yielded cubic phase NiO with morphologies similar to their hydroxide precursors. X-ray powder diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), and energy dispersive X-ray (EDX) analysis were used to characterize the as-prepared products. The role of pH in controlling the phase and morphology of the products was discussed.     

Improvement of Superconductivity with the Modification of Charge Reservoir Layer in (Cu0.5Tl0.5?xMx)Ba2Ca2Cu3O10?δ

The relatively higher electronegative elements (M = Pd, Nb, Bi, Hg) have been partially doped at Tl sites in Cu_0.5Tl_0.5−x M _x Ba₂O_4−δ (x=0,0.25) charge reservoir layer of Cu_0.5Tl_0.5−x M _x Ba₂Ca₂Cu₃O_10−δ superconductor. These elements may retain more oxygen in the charge reservoir layer due to their higher electronegativity as compared to Tl, and the higher population of oxygen in the charge reservoir layer can optimize the charge carriers’ density in the conducting CuO₂ planes. The optimum density of mobile charge carriers in the conducting CuO₂ increases Fermi wave-vector K _F and Fermi velocity v _F of the carriers, which results in the improvement of superconducting properties of the material.     

Impact resistant behaviour of RC slab strengthened with FRP sheet

To investigate the impact resistance of RC slabs strengthened with Fibre Reinforced Plastic (FRP) sheet to the back of the slab, falling-weight impact tests were conducted. Two loading types were applied: iterative loading and single loading. The impact load was applied to the centre of the RC slab with a free falling 300 kg steel striker with a diameter of 60 mm. A total of 12 RC slabs that were 1,650 (L) × 1,650 (W) × 150 (h) mm were used for these experiments. In this study, the strengthening method and material properties of the FRP sheet and the number of FRP sheet layers were varied. The results obtained from this study are as follows: (1) the impact resistance of the RC slabs can be improved by attaching a strengthened FRP sheet to the back surfaces; (2) the load bearing mechanism of RC slabs depends on the loading type and strengthening volume of the FRP sheet; and (3) the dynamic amplification factor is about two, which is independent of the load bearing mechanism of the RC slab and the strengthening volume and tensile rigidity of the FRP sheet.     

Radiological hazards of TENORM in precipitated calcium carbonate generated as waste at nitrophosphate fertilizer plant in Pakistan

The NORM (naturally occurring radioactive material) in phosphate rock is transferred as TENORM (technologically enhanced naturally occurring radioactive material) to phosphatic fertilizers and to the waste generated by the chemical processes. The waste generated at the NP (nitrophosphate) fertilizer plant at Multan in Pakistan is PCC (precipitated calcium carbonate). Thirty samples of the PCC were collected from the heaps of the waste near the fertilizer plant. Activity concentrations of radionuclides in the waste samples were measured by using the technique of gamma ray spectrometry consisting of coaxial type HPGe (high purity germanium) detector coupled with a PC (personal computer) based MCA (multichannel analyzer) through a spectroscopy amplifier. Activity concentrations of ²²⁶Ra, ²³²Th and ⁴⁰K in the waste samples were determined to be 273 ± 23 (173-398), 32 ± 4 (26-39) and 56 ± 5 (46-66) Bq kg⁻¹ respectively. The activity concentration of ²²⁶Ra in the PCC waste was found to be higher than that in naturally occurring calcium carbonate (limestone and marble) and in worldwide soil. Radiological hazard was estimated from indoor and outdoor exposure to gamma rays from the PCC. Indoor annual effective dose was higher than 1 m Sv. Potential radiological pollution in the environment from TENORM in the PCC has also been addressed.     

Ion-exchange synthesis of Co-functionalized titanate nanotubes and their application in electrochemical capacitors

Co-functionalized titanate nanotubes (Co-Ti-NTs) were successfully synthesized by means of an ion-exchange reaction. In contrast to the pristine titanate nanotubes (Ti-NTs), Co-Ti-NTs retained rich porous channels and owned even larger specific surface area and better electronic conductivity, which rendered electrons and OH^? ions easily contact the Co species uniformly distributed on their surfaces for energy storage at high rates. The Co-Ti-NTs delivered a specific capacitance (SC) of 124 F g^?1 at 0.4 A g^?1, and a SC degradation of ca. 7% after 1500 continuous cycling at 3 A g^?1, indicating that the Co-Ti-NTs were good candidates and/or even good supports for other electroactive materials for supercapacitors application.     

Synthesis and characterization of uniformly coated particles (cobalt compounds on copper compounds)

Spherical particles (～3 μm) of copper(II) oxalate were produced in the form of precipitated solids by gently mixing aqueous solutions of oxalic acid and copper nitrate with predetermined concentrations at room temperature. These particles were isolated from the mother liquor and then coated with cobalt basic carbonate. The coating trials involved heating of the aqueous dispersions, containing known amounts of the dispersed copper oxalate particles (cores), urea, and cobalt nitrate, at 70–85 °C for various periods of time with constant stirring. The heating process decomposed urea, increased pH, liberated carbonate ions, which resulted in the precipitation of the dissolved cobalt ions in the form of shells of cobalt basic carbonate around each core particle. The coating process was sensitive to the applied experimental parameters, since uniformly coated particles were obtained under a narrow range of coating mixture composition. In the absence of the cores, the same reactants solutions produced coating precursor particles (cobalt basic carbonate), when subjected to similar heating conditions. Physical and chemical analyses indicated that the coating material of the coated particles and the coating precursor particles had the same chemical compositions. The as-prepared core, coating precursor, and coated particles were converted into oxide forms by heating their dry powders at elevated temperatures under controlled heating conditions. The heat treatment produced obvious changes in the surface morphology of these particles due to loss of material. Moreover, the heat-treated particles preserved shape integrity to a maximum extent, showing their thermal stability. Selected batches of the as-prepared and heat-treated products were characterized by various physical methods.     

Ab initio study of AlCu2M (M = Sc,Ti and Cr) ternary compounds under pressures

The structural, electronic and elastic properties of the AlCu₂M (M = Sc, Ti and Cr) compounds in the pressure range of 0–100 GPa was investigated based on density functional theory. The calculated lattice parameters of the AlCu₂M compounds at zero pressure and zero temperature are in very good agreement with the existing experimental data. The bulk modulus, shear modulus and Young’s modulus increases with the increase of pressure, which indicates that higher materials hardness may be obtained when increasing pressures. The bulk modulus and Young’s modulus of AlCu₂Cr is the greatest under pressure. The shear modulus of AlCu₂Ti is the highest above 30 GPa, while that of the AlCu₂Sc is the strongest below 30 GPa. The calculated B/G values at zero and higher pressure indicated that they are ductile materials. The electronic densities of states and bonding charge densities have been discussed in details, revealing these compounds exhibit half-metallic behavior. In addition, the pressure dependences of Debye temperatures of AlCu₂M compounds have also been calculated. The results indicate that Debye temperatures increase with increasing pressure.     

Characterization and evaluation of some rapeseed oils

Rapeseed oil is used mostly in edible products. Four rapeseed oils, brown sarson and toria oils from West Pakistan, a Swedish oil and a Canadian oil, were characterized and examined relative to their suitability as edible oils. The various analytical data obtained are reported. The hydrogenated oils have consistency characteristics and plastic ranges which make them suitable for use as plastic fats. This work supported by a fellowship grant awarded by South East Asia Treaty Organization, Bangkok, Thailand. A laboratory of the So. Utiliz. Res. & Dev. Div., ARS, USDA.     

A single two electron transfer or high disproportionation: Electrochemical reduction of dinitrobibenzyl

Further electrochemical investigation and analysis of electrochemical data on 2,2′ and 4,4′-dinitrobibenzyl showed that these compounds reduce in two 1e steps with similar formal potentials. The disproportionation constants for 2,2′ and 4,4′-dinitrobibenzyl anion radicals as calculated from electrochemical data are 0.02 and 0.32 respectively.