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The main objective of this work is to provide a better understanding of the warm-up phase of high-intensity discharge lamps. As an example of application, we chose the high-pressure mercury lamp. Based on two-dimensional fluid model parameters, such as the electric current, the length and the diameter of the burner are modified and the effect of the convective transport is studied. This allows us to obtain a thorough understanding of the physics of these lamps in their transitory phase. The simulation of the warm-up phase is a must for the proper predictions of the lamp behavior and can be conducted by solving the energy balance, momentum, and Laplace’s equations for the plasma, using the frame of the local thermodynamic equilibrium coupled with the energy balance of the wall. [ABSTRACT FROM AUTHOR]

An electronic pulsed power supplier for High Intensity Discharge (HID) lamps is presented in this paper. The pulsed power supplier is obtained from the integration of a two current source AC/DC converter and a full-bridge inverter. The electronic supply provides to the lamp a different current form excitation (crenels and superposition of pulses). The lamp is represented in a model of simulation by its conductance model and coupled to its electronic power supply. Finally, some experimental results from a laboratory prototype are shown and compared with simulation. The general objective of this work consists in studying the effect of a current pulsed power supply on the electric and photometric behaviour of the discharge lamps, intended in particular for photochemistry. [ABSTRACT FROM AUTHOR]

Di(2-ethylhexyl) dithiophosphoric acid (D2EHDTPA) was examined for cadmium removal from phosphoric acid solutions. High extraction performance was achieved. By means of slope and saturation methods, the stoichiometry of the complex was postulated. Both methods indicated the presence of anhydrous CdR2 as being the metallic extracted complex, HR denoting the D2EHDTPA molecule. The stripping of cadmium from the organic phase was ensured by aqueous solutions of HCl; quantitative stripping was achieved with either HCl (4 M) or an HCl-NaCl mixture. [ABSTRACT FROM AUTHOR]

This paper deals with the solvent extraction of silver from thiourea leaching Ag ore liquors as an alternative to the traditional process involving cyanide. The investigation of the extraction mechanism of silver from acidic thiourea solution had not been clearly established to date. The extraction behavior of silver using di(2-ethylhexyl)dithiophosphoric acid (D2EHDTPA) and di(2,4,4-trimethylpentyl) thiophosphinic acid (CYANEX 302) was studied. The effect of various parameters such as concentrations of metal, mineral acid, thiourea, and extractant has been investigated. The extracted complexes have been identified through a slope method analysis as AgX(HX)5 for CYANEX 302 and AgX for D2EHDTPA, where HX denotes the extractant. Moreover, complete stripping was ensured with a mixture of NH4SCN and H2SO4. In addition we showed that a first step of extraction with D2EHPA or CYANEX 272 results in the preferential separation of Fe(III) from the Ag(I) leach solution. [ABSTRACT FROM AUTHOR]

The influence of a pulsed-current power supply on the electrical properties and the spectral radiant flux emitted by a germicidal ultraviolet (UV) lamp has been investigated, both experimentally and theoretically. A self-consistent collisional–radiative model has been developed and used to model the temporal behaviour of the plasma characteristics of the lamp operated in the pulsed mode. The model includes elastic and inelastic processes as well as ambipolar diffusion. The macroscopic properties of the plasma, including the electron temperature, electric fields, radiation and energy transfer due to various collisional processes, have been considered. To evaluate the energy emitted in the UV bandwidth, a photometric system composed of an integrating cylinder, a UV radiometer, a spectrograph and a charge-coupled device camera is mounted. This study provides a framework for the design of a pulsed-current power supply, which permits the generation of a single pulse or multiple pulses superimposed on a low-frequency square wave. [ABSTRACT FROM AUTHOR]

The extraction of nickel(II) from acidic aqueous solutions using a mixture of 2-ethylhexanal oxime (EHO) and bis(2-ethylhexyl) phosphoric acid (D2EHPA) in dodecane has been investigated as a function of total concentrations of each extractant, metal and protons. The aqueous salt concentration is proved to have no significant effect for both ammonium nitrate and chloride. The extracted organic complex is then Ni(Ox)2(HOx)2(HA)2 or Ni(HOx)4A2, where HA denotes the organo-phosphoric acid and HOx the oxime. A complementary isomolecular study has been achieved to confirm this stoichiometry. As aggregation plays a crucial role in extraction phenomenon, Vapor Pressure Osmometry (VPO) measurements have been carried out in order to determine the aggregation numbers for either the separate extractants or their mixtures. The bis(2-ethylhexyl) phosphoric acid is mainly under dimer and trimer forms, while no mixed aggregation is observed. [ABSTRACT FROM AUTHOR]

The extraction of nickel(II) from various aqueous solutions by 2-ethylhexanal oxime (EHO) in dodecane has been studied as a function of total concentrations of extractant, metal and salts and of the equilibrium pH. In the absence of salts, as well as in the presence of ammonium and sodium nitrates, the extracted complex is: Ni(EHO)5(H2O). In the complexing chloride medium, two different species exist, depending on acidity: for pH lower than 4, Ni(EHO)3 Cl2(H2O) and pH above 4, Ni(EHO)4Cl(H2O). 2-ethylhexanal oxime forms multimers. In dodecane The knowledge of these association degrees is very important when EHO is used as an extracting reagent. The EHO aggregation numbers have been determined by the VPO method (Vapour Pressure Osmometry) at three temperatures (24, 29 and 34°C) in a wide concentration range (0.03–0.77 mol.kg-1). EHO forms monomers, dimers and trimers. The formation constants of these aggregates have been estimated by numerical analysis. [ABSTRACT FROM AUTHOR]

Introduction: Acutemarital psychosis is an acute psychotic episode occurring in a particular context which is marriage. In fact, marriage represents an event with a very important emotional load especially in theArab-Muslim culture. This event can, in some people, induce a relapse of certain psychiatric disorders, particularly psychotic ones. We propose in this work to report two clinical observations concerning two brothers who both presented, a few years apart, an acute nuptial psychosis with two different evolutions. Objectives: Studing the characteristics of nuptial psychotic episode in a one family and the different evolution of each one. Methods: Reporting two clinical cases of two brothers who represented both acute psychotic episode in a nuptial context with different evolution. Results: The two patients are brothers with common psychiatric background which is their mother treated for chronic psychotic disorder. They were hospitalized in our psychiatric service for acute psychotic episode occuring in a nuptial context with chronic evolution for the first one and a partial recovery for the second one. Conclusions: Marriage represents an event with a very important emotional load especially in the Arab-Muslim culture. In thiscontext, acute psychotic episode can occur with different evolution for patients predisposed. Studing socio-cultral circumstances related to psychotic episode can help mental health professional to improve the quality of health care service. [ABSTRACT FROM AUTHOR]

• A process for the simultaneous recovery of silver and gold from leaching solutions is proposed • The approach allows recovering in a single stage the two metals, reducing the equipment required • Extraction of silver and gold is performed by D2EHDTPA • Mathematical models are proposed to predict the performance of the extraction and the stripping/scrubbing. This study is focused on the extraction and recovery of gold and silver from thiourea acid leaching ore liquors. In a first step, extraction is performed using di(2-ethylhexyl)dithiophosphoric acid (D2EHDTPA). The extraction of gold and silver takes place simultaneously, allowing the removal of both metals in a single equipment under the same operational conditions. Each metal is then recovered by selective stripping, using NH 4 SCN/H 2 SO 4 solutions to separate the silver from the D2EHDTPA. Such treatment is followed by a second stripping system, where a (NH 4) 2 S 2 O 3 solution is used to recover gold. A mathematical model is developed to represent all the operations in the process flowsheet. Through this model, it is predicted that, for properly selected operating conditions, recoveries higher than 99.9% for silver, gold and thiourea (to be recycled) can be obtained. The data predicted by the model has a good fit with previously reported experimental data. The proposed process is a more sustainable approach, in comparison with the traditional process involving cyanide, and has potential to be economically feasible. [Display omitted] [ABSTRACT FROM AUTHOR]