1,721,224 research outputs found
La dérégulation en droit du travail dans les pays socialistes
No full textNagy Laszlo. La dérégulation en droit du travail dans les pays socialistes. In: Revue internationale de droit comparé. Vol. 42 N°1, Janvier-mars 1990. pp. 27-35
Les partis politiques dans le mouvement national le cas de l'Algérie et de la Tunisie
No full textNagy Laszlo J. Les partis politiques dans le mouvement national le cas de l'Algérie et de la Tunisie. In: Cahiers de la Méditerranée, n°41, 1, 1990. États et pouvoirs en Méditerranée (XVIe-XXe siècles). Mélanges offerts à André Nouschi. Tome I. pp. 77-88
An electrochemical study of ammonium dihydrogen phosphate on Mg and Mg alloy electrodes
No full textIn this work, the electrochemistry of ammonium dihydrogen phosphate in aqueous solution on Mg and Mg AZ31 alloy (Al 3 wt%, Zn 1 wt%, balanced Mg) electrodes was studied using electrochemical characterization similar to electro-agglomeration and physical characterization to shed some light on the electrochemical mechanism of struvite formation as phosphate precipitation in waste. It was found that the Mg AZ31 alloy exhibited higher corrosion current densities (jcorr), therefore, higher Mg2+ dissolution rates compared to pure Mg. This finding was confirmed by ion chromatography (IC) analysis, in which the presence of Mg2+ was due to the oxidation of the Mg metal, and the higher Mg2+ concentration for the Mg AZ31 alloy 62.7 ppm vs. 57.5 ppm for pure Mg was in good agreement with the higher obtained corrosion rates (vcorr). Results also showed a phosphorus removal efficiency (PRem) of 16.8% with ~53 mL H2 production for pure Mg anode and 17.2% with ~61 mL H2 production for Mg AZ31 alloy. The precipitates formed on the Mg based discs were studied and analyzed by SEM, XRD, XPS, EDX while the physical characterizations of the obtained films corresponded to struvite (magnesium ammonium phosphate hexahydrate - MgNH4PO4*6H2O). It was found that (i) the thickness of the films was influenced by the applied scan rates, which also had a significant impact on the morphology, and (ii) hydrogen bubble formation influenced the precipitates whereby the film thicknesses were negatively impacted
The Electrochemistry of Ammonium Dihydrogen Phosphate, Disodium Phosphate, Ammonium Chloride on Mg-based and Polycrystalline Pt Electrodes
No full textIn this study, the electrochemical mechanisms of struvite formation were investigated by studying the behaviour of Mg-based and (poly)crystalline-Pt electrodes in the presence of ammonium dihydrogen phosphate, disodium phosphate, and ammonium chloride solutions. It was found that a precipitate was formed on the Mg-based electrodes, while the poly-Pt electrode showed typical voltammetric features in aqueous electrolytes. The structure, morphology, and composition of the electrochemically obtained precipitates collected from the surface of the Mg-based electrodes were analyzed by scanning electron microscopy (SEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). The results showed that the precipitate morphology was impacted by the composition of the electrolytes and the purity of the magnesium. Moreover, the Tafel kinetics and corrosion rates (vcorr) directly correlated with the electrolyte and the electrode material compositions, whereby both showed a general increase when the Mg-based electrodes were employed in the presence of chloride anions. The Tafel slopes (β) obtained for the oxygen reduction reaction (ORR) with the poly-Pt electrode showed a significant difference between the forward and reverse potential scans in the various electrolytes used, a finding which was mainly attributed to the adsorption of hydroxide species, alkali cations, and phosphate anions to the surface whereby these species blocked the ORR active sites
Electroless Production of Fertilizer (Struvite) and Hydrogen from Synthetic Agricultural Wastewaters
No full textThe drive towards sustainable phosphorous (P) recovery from agricultural and municipal wastewater streams has intensified. However, combining P recovery with energy conservation is perhaps one of the greatest challenges of this century. In this study, we report for the first time, the simultaneous electroless production of struvite and di-hydrogen from aqueous ammonium dihydrogen phosphate (NH4H2PO4) solutions in contact with either a pure magnesium (Mg) or a Mg alloy as the anode and 316 stainless steel (SS) as the cathode placed in a bench-scale electrochemical reactor. During the electroless process (i.e., in the absence of external electrical power), the open circuit potential (OCP), the formation of struvite on the anode, and the generation of di-hydrogen at the cathode were monitored. We found that struvite is formed, and that struvite crystal structure/morphology and precipitate film thickness are affected by the concentration of the HnPO4n-3/NH4+ in solution and the composition of the anode. The pure Mg anode produced a porous, 0.6-4.1 µm thick film, while the AZ31 Mg alloy produced a more compact, 1.7-9.9 µm thick struvite film. Kinetic analyses revealed that Mg dissolution to Mg2+ followed mostly a zero-order kinetic rate law for both Mg anode materials and the rate constants (k) depended upon the struvite layer morphology. Fourier-transform infrared spectrometry (FT-IR), X-ray diffraction (XRD), and scanning electron microscopy (SEM) indicated that the synthesized struvite was of high quality. The di-hydrogen and Mg2+ in solution were detected by a gas chromatography (GC)-thermal conductivity detector (TCD) and ion chromatography (IC), respectively. Furthermore, we fully demonstrate that the reactor was able to remove ~73% of the HnPO4n-3 present in a natural poultry wastewater as mainly struvite. This study highlights the feasability of simultaneously producing struvite and di-hydrogen from wastewater effluents with no energy input in a green and sustainable approach
A novel planar electrochemical cell for voltammetric measurements in thin hydrogel films
Get PDFThe fabrication of a planar micro electrochemical cell is presented.The simplicity and the relative low cost of this kind of cells make them very interesting and promising in the development of chemical and biochemical sensors. The utilization of microelectrodes as working electrodes in planar electrochemical cells is preferred to the conventional macroelectrodes because microelectrodes can be used in highly resistive media, have short response time, and excellent signal to noise ratio. In electrochemical sensor applications, the microelectrode surfaces are commonly modified with multiple layers to boost selectivity, control sensitivity, or to provide a biocompatible interface between the sensor and its environment. In this work, the fabricated set of bundled electrodes is covered with a hydrogel as an example of its potential use as electrochemical gas sensor. All micro electrochemical cells were characterized by cyclic voltammetry (CV) and the results were analyzed with different statistical methods.Fil: Kékedy Nagy, Laszlo. University of Memphis; Estados UnidosFil: Garay, Fernando Sebastian. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigaciones en Físico-química de Córdoba. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Instituto de Investigaciones en Físico-química de Córdoba; ArgentinaFil: Lindner, Ernö. University of Memphis; Estados Unido
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
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