The Experts below are selected from a list of 47421 Experts worldwide ranked by ideXlab platform
R.m. Amer - One of the best experts on this subject based on the ideXlab platform.
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Cadmium biosorption by a cadmium resistant strain of Bacillus thuringiensis: regulation and optimization of cell surface affinity for metal cations
Biometals, 2000Co-Authors: E.r. El-helow, Soraya A Sabry, R.m. AmerAbstract:A marine bacterial strain putatively identified as Bacillus thuringiensis strain DM55, showed multiple heavy metal resistance and biosorption phenotypes. Electron microscopic studies revealed that DM55 cells are encased in anionic cell wall polymers that can immobilize discrete aggregates of cations. Factors affecting cell surface affinity for metal cations, monitored by means of Cd^2+ binding capability, are investigated. The mechanisms of cadmium resistance and Cd^2+ biosorption by the bacterium appeared to be inducible and coincident. Medium components affecting metal removal under cadmium-stressed growth conditions were explored based on the application of two sequential multi-factorial statistical designs. Concentrations of Potassium Phosphates and peptone were the most significant variables. Optimized culture conditions allowed DM55 cells grown in the presence of 0.25 mM CdCl_2 to remove about 79% of the metal ions within 24 h with a specific biosorption capacity of 21.57 mg g^−1 of biomass. Both fresh and dry cells of DM55 prepared under cadmium-free optimal nutrient condition were also able to biosorb Cd^2+. In addition to the concentration of phosphate in the medium, KinA, a major phosphate provider in the phosphorelay of Bacillus cells, was also demonstrated to regulate the magnitude of cell surface affinity for cadmium ions.
Loic Barre - One of the best experts on this subject based on the ideXlab platform.
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colloidal sodium and Potassium Phosphates in organic medium synthesis and analysis
Journal of Colloid and Interface Science, 1998Co-Authors: Bruno Delfort, Laurent Normand, Philippe Dascotte, Loic BarreAbstract:Colloidal dispersions of sodium and Potassium Phosphates in a hydrocarbon medium have been synthesized by reacting, under specific conditions, aqueous sodium or Potassium hydroxyde with tetraphosphorous decasulfide in hydrocarbon solvent in the presence of a surfactant such as alkylarylsulfonic acid. The resulting products can be defined as a distribution of inorganic particles stabilized by sodium or Potassium alkylaryl sulfonate in a reverse-micelle type association. The chemical structures of the mineral cores are determined using 31P NMR, potentiometric titration and elemental analysis. The core particles were found to be respectively a mixture of sodium (poly)Phosphates and a mixture of Potassium (poly)Phosphates. Inorganic core and organic surfactant balances were determined using thermogravimetric analysis. The weight ratio of mineral core part to organic surfactant part is found about to be 1.6 for Na derivative and 2.4 for K derivative. The morphological characterization of the colloidal dispersion has been investigated using Small Angle X-ray Scattering, Transmission Electron Microscopy and Wide Angle X-ray Scattering. The inorganic particles appear as cristallized particles with diameters ranging from 50 to 360 A.
E.r. El-helow - One of the best experts on this subject based on the ideXlab platform.
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Cadmium biosorption by a cadmium resistant strain of Bacillus thuringiensis: regulation and optimization of cell surface affinity for metal cations
Biometals, 2000Co-Authors: E.r. El-helow, Soraya A Sabry, R.m. AmerAbstract:A marine bacterial strain putatively identified as Bacillus thuringiensis strain DM55, showed multiple heavy metal resistance and biosorption phenotypes. Electron microscopic studies revealed that DM55 cells are encased in anionic cell wall polymers that can immobilize discrete aggregates of cations. Factors affecting cell surface affinity for metal cations, monitored by means of Cd^2+ binding capability, are investigated. The mechanisms of cadmium resistance and Cd^2+ biosorption by the bacterium appeared to be inducible and coincident. Medium components affecting metal removal under cadmium-stressed growth conditions were explored based on the application of two sequential multi-factorial statistical designs. Concentrations of Potassium Phosphates and peptone were the most significant variables. Optimized culture conditions allowed DM55 cells grown in the presence of 0.25 mM CdCl_2 to remove about 79% of the metal ions within 24 h with a specific biosorption capacity of 21.57 mg g^−1 of biomass. Both fresh and dry cells of DM55 prepared under cadmium-free optimal nutrient condition were also able to biosorb Cd^2+. In addition to the concentration of phosphate in the medium, KinA, a major phosphate provider in the phosphorelay of Bacillus cells, was also demonstrated to regulate the magnitude of cell surface affinity for cadmium ions.
Bruno Delfort - One of the best experts on this subject based on the ideXlab platform.
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colloidal sodium and Potassium Phosphates in organic medium synthesis and analysis
Journal of Colloid and Interface Science, 1998Co-Authors: Bruno Delfort, Laurent Normand, Philippe Dascotte, Loic BarreAbstract:Colloidal dispersions of sodium and Potassium Phosphates in a hydrocarbon medium have been synthesized by reacting, under specific conditions, aqueous sodium or Potassium hydroxyde with tetraphosphorous decasulfide in hydrocarbon solvent in the presence of a surfactant such as alkylarylsulfonic acid. The resulting products can be defined as a distribution of inorganic particles stabilized by sodium or Potassium alkylaryl sulfonate in a reverse-micelle type association. The chemical structures of the mineral cores are determined using 31P NMR, potentiometric titration and elemental analysis. The core particles were found to be respectively a mixture of sodium (poly)Phosphates and a mixture of Potassium (poly)Phosphates. Inorganic core and organic surfactant balances were determined using thermogravimetric analysis. The weight ratio of mineral core part to organic surfactant part is found about to be 1.6 for Na derivative and 2.4 for K derivative. The morphological characterization of the colloidal dispersion has been investigated using Small Angle X-ray Scattering, Transmission Electron Microscopy and Wide Angle X-ray Scattering. The inorganic particles appear as cristallized particles with diameters ranging from 50 to 360 A.
Soraya A Sabry - One of the best experts on this subject based on the ideXlab platform.
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Cadmium biosorption by a cadmium resistant strain of Bacillus thuringiensis: regulation and optimization of cell surface affinity for metal cations
Biometals, 2000Co-Authors: E.r. El-helow, Soraya A Sabry, R.m. AmerAbstract:A marine bacterial strain putatively identified as Bacillus thuringiensis strain DM55, showed multiple heavy metal resistance and biosorption phenotypes. Electron microscopic studies revealed that DM55 cells are encased in anionic cell wall polymers that can immobilize discrete aggregates of cations. Factors affecting cell surface affinity for metal cations, monitored by means of Cd^2+ binding capability, are investigated. The mechanisms of cadmium resistance and Cd^2+ biosorption by the bacterium appeared to be inducible and coincident. Medium components affecting metal removal under cadmium-stressed growth conditions were explored based on the application of two sequential multi-factorial statistical designs. Concentrations of Potassium Phosphates and peptone were the most significant variables. Optimized culture conditions allowed DM55 cells grown in the presence of 0.25 mM CdCl_2 to remove about 79% of the metal ions within 24 h with a specific biosorption capacity of 21.57 mg g^−1 of biomass. Both fresh and dry cells of DM55 prepared under cadmium-free optimal nutrient condition were also able to biosorb Cd^2+. In addition to the concentration of phosphate in the medium, KinA, a major phosphate provider in the phosphorelay of Bacillus cells, was also demonstrated to regulate the magnitude of cell surface affinity for cadmium ions.