Effect Of Phosphate Ions Research Articles

Effect of phosphate ions on the fluorescence of tryptophan derivatives: Implications in fluorescence investigation of protein-nucleic acid complexes

In order to test the ability of phosphate groups to quench the fluorescence of tryptophan in protein-nucleic acid complexes we have studied the effect of various phosphate ions on the fluorescence of tryptophan derivatives. Unsubstituted and monoalkyl monoanions (H 2PO 4 − and CH 3OPO 3H −) quench the fluorescence of all investigated indole derivatives while the dimethyl anion (CH 3O) 2 PO 2 − does not. This suggests that quenching of tryptophan fluorescence by phosphate monoanions requires the presence of an acidic OH group and could be due to a proton transfer from the phosphate ion to the indole chromophore. Trianions (PO 3− 4) which are strong proton acceptors quench the fluorescence of all tryptophan derivatives except N(1)-methyl tryptophan. This result strongly supports our proposal that quenching of tryptophan fluorescence by phosphate trianions occurs through deprotonation of the NH indole group. Bianions (HPO 2 4 and CH 3O PO 2− 3) quench the fluo-rescence of several indole derivatives including N-acetyl tryptophanamide but have no effect on tryptophan or N(1)-methyl tryptophan. From our results we conclude that phosphate groups of nucleic acids are not able to quench the fluorescence of tryptophyl residues in proteinnucleic acid complexes except if an accessible residue is located near a phosphorylated polynucleotide chain end.

Effect of phosphate ions on zinc dissolution in alkaline solutions

Effect of phosphate ions on zinc dissolution in alkaline solutions

Effect of phosphate ions on zinc dissolution in alkaline solutions

Effect of phosphate ions on zinc dissolution in alkaline solutions

The Polymorphic Crystallization of TiO2 under Hydrothermal Conditions. I. The Effect of Phosphate Ions on the Selective Crystallization of Anatase

Abstract The hydrothermal growth of anatase has been investigated at 480–650 °C and 500–1000 atm. Only rutile was formed in KF solutions. On the other hand, anatase was found to crystallize in solutions containing 5 wt% KF+0.1–10 wt% K2HPO4 at temperatures up to 600 °C, accompanied by small amounts of K2Ti6O13 on the addition of 5–10 wt% of K2HPO4. The optimum growth conditions were: mineralizer solution, 5 wt% KF+1–2.5 wt% K2HPO4; temperature, 550–600 °C; pressure, 1000 atm. Anatase crystals were found as irregular aggregates of dipyramidal grains, blue and transparent. Individual crystals grown at a low supersaturation were characterized by well-developed {101} and {103} faces. The observed habit agrees with the expectations based on Hartman’s PBC theory. The presence of phosphate ions favored anatase formation in NH4F solutions as well, and the retrograde solubility of TiO2 was observed. The reaction scheme for anatase formation has been proposed. The polymorphic crystallization of TiO2 under hydrothermal conditions has been shown to be greatly affected by the complexing anions, such as fluoride or phosphate, in mineralizer solutions.

Effects of impurity ions upon some performance indicators in the autoclave deposition of copper

1. In the manufacture of copper powders of any predetermined properties by the autoclave process, it is important to bear in mind the presence in the process solution of NO3−, Cl−, or PC43− ions, which exert a specific influence upon the properties of the resultant powder. 2. Phosphate and chloride ions do not affect the kinetic parameters of the process, but nitrate ions appreciably lower the rate of powder deposition, particularly at high concentrations of free sulfuric acid in the solution. 3. The addition of nitrate ions leads to the appearance of needle-shaped particles. Increasing the concentration of chloride ions promotes the formation of equiaxed particles and growth in the yield of coarse powder fractions and in the apparent density and flowability of the powder. The effects of phosphate ions in the solution upon the properties of the powder are the reverse of those of chloride ions.

Adsorption of salivary proteins by hydroxyapatite: effects of phosphate ions and interdependence of the effects of phosphate and hydrogen ions.

Phosphate ions at physiological concentrations in saliva inhibited adsorption of salivary proteins by hydroxyapatite. Adsorption was related inversely to the concentration of phosphate. Removal of phosphate from saliva abolished or decidedly lowered the stimulating effect of hydrogen ions on adsorption of salivary proteins. Lowering the pH decreased, abolished, or reversed the adsorption inhibitory effect of phosphate.

The effect of the pH and phosphate ions on the precipitate formation reaction of sodium ions with pyroantimonate.

The effect of phosphate ions and the pH of the solution on the precipitation of Na-pyroantimonate was studied by a quantitative method. The presence of phosphate ions has an inhibitory effect on the formation of Na-pyroantimonate precipitate. The inhibiting effect decreases with the increasing concentration of hydroxyl ions. In the absence of phosphate ions at pH 9.5 Na+-ions precipitate completely. The inhibiting effect is explained by a complex formation reaction of the phosphate ions with the antimony (V) ions.

Anodic Polarization Characteristics of Phosphated Steels

Abstract The problem of providing a meaningful evaluation of the corrosion resistance of phosphated steel for the dual purposes of quality control and of improving the phosphate coating has a long and arduous history. The electrochemical characteristics of zinc-phosphated mild steels have been investigated to determine the repeatability, significance, and possible applications of such data. This investigation resulted in a precise electrochemical procedure that can distinguish between steels with zinc phosphate coatings of different quality and crystal structure. When zinc-phosphated mild steels are polarized anodically in 0.6M ammonium nitrate solution, different steels with the same nominal composition and phosphate treatment exhibit active-passive corrosion behavior with current density values that vary considerably over a narrow potential range. These critical current densities, with certain exceptions, vary in relation to the rust creepage corrosion evaluations of coated specimens in salt spray and to phosphate crystal structure. The effects of phosphate ions and of pH changes on the unique anodic polarization characteristics of phosphated steels were studied by simulating conditions that exist at the steel-phosphate-solution interfaces. Anion adsorption is discussed as a basis for the complicated behavior reflected in the anodic polarization data.