Informe de la campaña ARGELIA0204 para la evaluación de recursos demersales en las costas de Argelia (Mediterráneo sud-occidental)

RESUMEN: Del 5 de Febrero al 8 de Marzo de 2004 se llevó a cabo la campaña de prospección pesquera con arrastre de fondo ARGELIA0204 en aguas de Argelia, a bordo del B/O Vizconde de Eza. Se realizaron 114 pescas (6 nulas) entre 40 y 760 m de profundidad. Se presentan los resultados de las capturas realizadas en esta campaña y se analizan los índices de abundancia y biomasa de las especies más importantes, así como su distribución de tallas, por sector geográfico y estrato batimétrico. Se comparan los rendimientos y las tallas obtenidos con los de la campaña realizada en 2003 en la misma área y con otras campañas realizadas en el Mediterráneo.RÉSUME: Rapport de la campagne ARGELIA0204 portant évaluation des ressources demersaux des côtes Algériennes (Méditerranée sud-occidental).- Du 05 du Février au 8 du Mars 2004, s’est réalisée une campagne de prospection par chalutage du fond ARGELIA0204 des côtes Algériennes, a bord du B/O Vizconde de Eza. 114 traits de pêche (6 annulées) ont été effectue entre 40 et 800 m de profondeur. Les résultats des captures réalisées durant cette campagne et l’analyse des indices d’abondance et biomasse des espèces les plus importantes sont présentés, par secteur, par aire géographique et strate bathymétrique, ainsi que leurs distributions de tailles par secteur géographique et strate bathymétrique. Les rendements et les tailles obtenus ont fait l’objet d’une comparaison avec les autres campagnes réalisées dans la Méditerranée.ABSTRACT: Report of the ARGELIA0204 survey for the assessment of the deep-sea demersal resources off Algerian coast (south-western Mediterranean).- From 5 February to 8 March 2004 the bottom-trawl survey ARGELIA0204 was developed in waters off Argelia, on board R/V Vizconde de Eza. 114 hauls (6 null) were carried out between 40 and 800 m depth. The results on the captures obtained during this survey are shown and abundance and biomass indexes of the most important species are analyzed by geographic sector and area, and bathymetric stratum, as their size distribution by geographic sector and bathymetric stratum. Yields and sizes obtained are compared to those from other surveys carried out in the Mediterranea

The effects of Ag, Mg, and Pr doping on the superconductivity and structure of BSCCO

AbstractThe influence of Ag, Mg, and Pr additions and co-additions on microstructure and phase formation of Bi2Sr2CaCu2O8+d (Bi2212) system is investigated. Polycrystalline Bi2212 samples were synthesized in air by solid state reaction method. Phase analysis, micro structural observations and magnetic properties were carried out by X-ray diffraction (XRD), scanning electron microscopy (SEM) and A.C. susceptibility measurements respectively. XRD results reveal two main phases (Bi-2201 and Bi2212). SEM photographs show that the substitution by Ag, Mg or Pr affects the mechanism of the grains growth. The undoped sample has a critical temperature Tc of 65 K while in the Mg and Ag containing compounds the Tc is 77 K and 75 K respectively. The Pr containing compound exhibits no superconductivity. A valence of the Pr ion higher than 3+ in the lattice supports the holefilling mechanism of the suppression of superconductivity

Preliminary assessment of the performance of oyster shells and chitin materials as adsorbents in the removal of saxitoxin in aqueous solutions

<p>Abstract</p> <p>Background</p> <p>This study evaluated the adsorption capacity of the natural materials chitin and oyster shell powder (OSP) in the removal of saxitoxin (STX) from water. Simplified reactors of adsorption were prepared containing 200 mg of adsorbents and known concentrations of STX in solutions with pH 5.0 or 7.0, and these solutions were incubated at 25°C with an orbital shaker at 200 RPM. The adsorption isotherms were evaluated within 48 hours, with the results indicating a decrease in STX concentrations in different solutions (2–16 μg/L). The kinetics of adsorption was evaluated at different contact times (0–4320 min) with a decrease in STX concentrations (initial concentration of 10 μg/L). The sampling fractions were filtered through a membrane (0.20 μm) and analyzed with high performance liquid chromatography to quantify the STX concentration remaining in solution.</p> <p>Results</p> <p>Chitin and OSP were found to be efficient adsorbents with a high capacity to remove STX from aqueous solutions within the concentration limits evaluated (> 50% over 18 h). The rate of STX removal for both adsorbents decreased with contact time, which was likely due to the saturation of the adsorbing sites and suggested that the adsorption occurred through ion exchange mechanisms. Our results also indicated that the adsorption equilibrium was influenced by pH and was not favored under acidic conditions.</p> <p>Conclusions</p> <p>The results of this study demonstrate the possibility of using these two materials in the treatment of drinking water contaminated with STX. The characteristics of chitin and OSP were consistent with the classical adsorption models of linear and Freundlich isotherms. Kinetic and thermodynamic evaluations revealed that the adsorption process was spontaneous (ΔG_ads < 0) and favorable and followed pseudo-second-order kinetics.</p