Assessment of Trace Elements in Soils and Mine Water Surrounding a Closed Manganese Mine (Anti Atlas,Morocco)

Five mine water samples, 23 topsoil samples, and four mine waste (tailings) samples were collected to assess the effects of a closed Moroccan Mn mine. Based on the pH, electrical conductivity, and concentrations of sulphate, Cu, Zn, As, Cd, Pb, and Mn, mining has not adversely influenced mine water quality. Soil samples were analyzed for 23 chemical elements and the results were interpreted by univariate and multivariate statistical techniques. Based on an enrichment factor (EF) calculation, only Cd, As, V, and Mn were selected for further study. Geochemical background (GB) and geoaccumulation index (I_geo) were determined for these elements to differentiate between geogenic and anthropogenic enrichment. The GB values showed that the Tiwiyyine soils contained a high geogenic content of Cd, As, V, and Mn that reflected the geochemistry of the parental rocks in this mineralized region. The I_geo calculation revealed that these soils were moderately influenced by anthropogenic activity, which had increased the concentrations of those elements. Finally, geochemical maps revealed that mining was likely responsible for the anthropogenic soil pollution.     

Optical modeling of waveguide photonic nanostructures using theradiation spectrum method (RSM) with evanescent modes

In this work, we study the effects of the evanescent modes in the simulation and modeling of optical integrated circuits based on photonic bandgap structures. We show that the contribution of these modes in the energy transfer in structures like the MOEM structures, can not be neglected. The radiation spectrum method, recently developed by the authors for the guided wave devices, is thus extended to account for the evanescent mode propagation. Applying this technique on an air-gap in a suspended waveguide a model of this gap is developed in terms of its parameters. This model is then integrated in an all optical simulator to predict the performance of photonic structures. Such technique enables to design and to optimize the photonic integrated circuits taking the evanescent modes effects into account     

Electrodeposition of catalytically active Co-Ni-Tl alloy powders from dilute sulphate baths

Cobalt-nickel-thallium alloy powders were electrodeposited from dilute metal sulphate baths of composition: 0.007–0.0245 mol l^–1 CoSO₄·7H₂O, 0.0245–0.007 mol l^–1 NiSO₄·6H₂O, 0.001 mol l^–1 TlCl, 0.5 mol l^–1 (NH₄)₂SO₄, 0.07 mol l^–1 Na₂SO₄·10H₂O and 0.4 mol l^–1 H₃BO₃. The cathodic polarization curves were traced during electrodeposition and utilized in the discussion of a reaction mechanism for the electrolytic powder deposition. The alloy composition and the cathodic current efficiency were influenced to a great extent by the bath composition (I) and slightly by the deposition current density (II). Irrespective of variables (I) and (II), the electrodeposition of the alloy belonged to the anomalous type. The surface morphology and the catalytic activity, towards the decomposition of 0.4% H₂O₂ solution, of the as-deposited alloy powders were affected predominantly by the percentage of cobalt in the alloy. X-ray diffraction studies showed that the alloys consisted mainly of the face-centred cubic nickel phase either alone or with minor proportions of face-centred cubic cobalt phase and hexagonal close-packed -cobalt phase. The occurrence of the latter phases was observed only in the alloys with a higher cobalt percentage than nickel.     

The anodic oxidation of valve metals—II. The influence of the anodizing conditions on the transport processes during the anodic oxidation of zirconium

The transport numbers for metal and oxygen in anodic ZrO₂ have been measured as a function of the oxide film thickness, growth rate, electrolyte composition, metal surface finish and electric field using ²²²Rn as an inert marker. The field in the oxide has also been determined as a function of current density and electrolyte composition.

The metal transport number apparently diminishes with increasing oxide thickness but this is shown to arise from the formation of a hydrated layer on the oxide surface which leads to greater energy loss of the -particles and apparently greater burying. However, this effect only has significance for thin films. For thick films the measured transport numbers are independent of thickness but show increases from very low values as the current density increases and with changes in the anodizing electrolyte in the sequence: sodium hydroxide; ammonium borate; sodium sulphate. The maximum metal transport number observed was 0.22 for 0.5 M sodium sulphate at 50 mA current density. The field in the oxide also increased with increase in current density and with electrolyte in the same sequence.     

Biochemical and technological studies on the production of isolated guar protein

Guar seeds contain 32% crude protein. Therefore, attempts were made to prepare protein isolates from guar seed flour (GSF) by extraction in different media (distilled water, salt solution, alkali solution alone or in combination) followed by a precipitation at acid pH. From the four technologies adopted, mixed salt-alkali solution was found to be the most satisfactory for extraction of protein from GSF. The highest amount of product was obtained in the mixed technology along with the highest amount of protein (87.5%). Protein isolates were also nutritionally evaluated following well-established rat bioassay procedures in a comparative study with casein as standard. The protein isolates are rich in lysine but poor in sulphur-containing amino acids such as methionine and cysteine. Protein isolates obtained by mixed salt-alkali solution showed high water and oil absorption as well as good emulsifying and foaming stability. The results indicate that protein isolates can be used as a supplementary source of protein in different food industries.     

The lipids of various fungi grown on an artificial medium

The lipids extracted from various fungi belonging to the generaAspergillus, Fusarium andPenicillium cultivated on Davis medium were studied. The fatty acids from fungal lipids were fractionated by gas liquid chromatography (GLC) and the main fatty acids were palmitoleic, oleic, stearic, linoleic and arachidic. The results demonstrated that the fatty acid composition of various fungi could be used as criteria for fungal taxonomy. The unsaponifiable matter of the fungi could be divided into two fractions, i.e., hydrocarbons and sterols. The hydrocarbon fraction constitutes an important part because its amount ranged from 30.14 to 80.97% according to the fungal species. The sterol fraction of the unsaponifiable part of fungal lipids was much simpler in composition. Analysis by GLC indicated that sterol composition could be used to differentiate among fungi belonging to different genera as well as among species belonging to one genus.     

The effect of dye chemical structure on adsorption on activated carbon: a comparative study

The effect of the molecular structure of dyes Eriochrome Black T and Bromophenol Blue on their adsorption on the surface of activated carbon manufactured from locally available biosorbent has been studied. Batch experiments were performed to investigate factors that may affect the adsorption process. The effect of stirring rate was investigated in the range 0–240 rpm, with an initial concentration of 4–100 mg/l and a stirring time of 0–400 min. The mechanism and rate of adsorption were investigated for both dyes using pseudo‐first‐order, pseudo‐second‐order, intraparticle diffusion, and liquid film diffusion models. The monolayer adsorption capacities for Eriochrome Black T and Bromophenol Blue were found to be 36.5 and 39.68 mg/g respectively. The difference in dye uptake was attributed to the presence of the electron‐withdrawing bromine group in Bromophenol Blue. Results showed that the Langmuir isotherm best fitted the adsorption of the two dyes on the prepared activated carbon. The pseudo‐second‐order model best fitted the experimental data, and liquid film diffusion and intraparticle diffusion were the controlling adsorption mechanisms.