Characterisation of a uranium ore using multiple X-ray diffraction based methods

Uranium bearing ores are often a complex mixture of minerals and compounds, a number of which are not of economic importance and are commonly referred to as gangue materials. In order to improve the efficiency of the dissolution stage of the overall uranium extraction process, a greater understanding of the minerals and compounds present in the ore is required. A greater knowledge of the gangue materials present is important as they can influence various aspects of the dissolution process such as providing potential adsorption sites for aqueous uranium species and through influencing the equilibrium of reactions involving aqueous uranium species. In this study the mineralogy of a uranium ore was investigated using a range of X-ray diffraction (XRD) based methods including in situ high temperature XRD and XRD using a synchrotron beam line. The results obtained from standard XRD (Cu Kα), high temperature XRD and synchrotron XRD (16.534 keV) were compared and a number of minerals were identified. The improved spatial resolution and intensity of the synchrotron data allowed for superior phase identification of a variety of minerals where standard X-ray techniques gave inconclusive results.     

Schottky diode solar cells on electrodeposited copper phthalocyanine films

Schottky diode solar cells were fabricated on electrodeposited films of copper phthalocyanine (CuPc). The aluminum contact was deposited by two methods, viz. thermal evaporation and electron beam evaporation; the materials and electro-optical characteristics of these devices were compared. We achieved the highest ever reported open-circuit voltage of 1.19 V with the electrodeposited CuPc films. This is in contrast to an open-circuit voltage of 0.907 V reported in Schottky diode cells with evaporated CuPc films. β-Phase dominance in electrodeposited CuPc films was thought to be a major factor in enhanced performance. Effects of varying the CuPc thickness on the device performance were investigated.     

Mitigating the health and safety influence of subcontracting in construction: The approach of main contractors

Subcontracting is noted for its adverse health and safety (H&S) influence in construction. Using interviews with five of the top 20 UK contractors and one medium-sized contractor, this study explored how main contractors manage the H&S influence of subcontracting with a focus on their in-house measures. Some in-house measures found are: restricting the layers of subcontractors on projects; working with a regular chain of subcontractors; implementing a H&S reward scheme for subcontractors; and insisting on non-working subcontractor foremen who have direct responsibility for the safety of workers in their trade. These measures appear to be influenced by clients, industry peer groups, and the moral justification for occupational H&S, and they offer inter-organisational learning opportunities for contractors in devising measures to mitigate the H&S influence of subcontracting. These findings should also allay concerns that removing some of the legislative hurdles in connection with on-going red tape debate will result in poorer H&S.     

Cobalt molybdenum oxide catalysts for selective oxidation of cyclohexane

Oxidation of cyclohexane has been carried out using molecular oxygen over cobalt molybdenum oxide (CoMoO₄) catalysts in solvent free conditions. The catalysts were prepared using citrate method with three different molar ratios of Co:Mo, 1:1, 1:2, and 2:1 along with individual oxides for comparative studies. While all the catalysts showed significant activity and selectivity, CoMoO₄ with 1:1 ratio showed the best performance compared to the others with a conversion of 7.38%, with selectivity to cyclohexanol and cyclohexanone (KA oil) of 94.3%, in 1 h. The performance of the catalyst, has been studied as a function of oxygen pressure, reaction temperature, and catalyst loading. It was observed that the catalyst deactivates during the course of the reaction. The reasons for deactivation and methods for restoring the activity have been studied. A kinetic model is presented that captures the complex kinetics and matches well with the experimental data. © 2016 American Institute of Chemical Engineers AIChE J, 62: 4384–4402, 2016     

Influence of Substrate Temperature on the Properties of Cobalt Oxide Thin Films Prepared by Nebulizer Spray Pyrolysis (NSP) Technique

Cobalt oxide thin films are prepared by the nebulizer spray pyrolysis technique using cobalt chloride as the precursor material. The structural, optical, morphological and electrical properties are investigated as a function of substrate temperature (300–450 °C). The X-ray diffraction (XRD) analysis reveals that all the films are polycrystalline in nature, having cubic structure with preferential orientation along the (111) plane. The optical spectra show that the films are transparent (68 %) in the IR region. The optical band gap values are calculated for different substrate temperature. Photoluminescence (PL) spectra of the films indicate the presence of indigo, blue and green emission peaks with an ultraviolet emission peak centered around 368nm. SEM images reveals small sphere-like structures for the prepared Co3O4 films. The maximum conductivity obtained is 1.48 x 10?3 S/cm at 350 °C. The activation energy varies between 0.039 and 0.138 eV for the substrate temperature variation from 300-450 Q°C.     

Design and Compressive Analysis of Junctionless Multigate FinFET Towards Low Power and High Frequency Applications

Silicon - Advances in microelectronics have enabled smaller technical nodes, lower threshold voltages, and greater working frequencies. Even though VLSI circuit performance and power consumption...     

Economical treatment of reverse osmosis reject of textile industry effluent by electrodialysis–evaporation integrated process

Membrane separation methods such as electrodialysis (ED) can reduce the volume load on evaporators by facilitating further concentration of rejects from reverse osmosis (RO) plants. ED studies were carried out on a bench-scale system using five membrane cell pairs to obtain a textile effluent concentrate containing approximately 6 times the quantity of salts present in the RO reject. The limiting current densities were determined to be in the range 2.15–3.35 amp/m² for feed flow rates varying from 18 to 108 L/h. Apart from feed rate, the influence of volume of concentrate and current on membrane performance was evaluated to optimize current utilization. An estimation of energy requirement of an integrated process constituting ED and evaporation for concentration of inorganics present in textile effluent from 4.35% to 24% was made and found to be approximately one eighth of the operating cost incurred by evaporation alone. Detailed design of a commercial ED system revealed that a membrane area of 13.1 m² was required to treat a feed rate of 1500 L/h. The payback period to recover capital investment was found to be 110 days.