Effects of two new additives on the initial rate of peroxodisulphate electrosynthesis

1983 ◽  
Vol 48 (7) ◽  
pp. 1956-1962 ◽  
Author(s):  
Jan Balej ◽  
Martin Kadeřávek ◽  
Hermann Matschiner ◽  
Wolfgang Thiele
Keyword(s):  
Initial Rate ◽  
Additive Concentration ◽  
Reaction Conditions ◽  
Maximum Increase ◽  
Ion Formation ◽  
Platinum Anode ◽  
Maximum Current

Two new additives, dipotassium cyanimidodithiocarbonate (DKDK) and 5-thio-2-imido-3,4-disulphazolidine (TIDSAL), were tested for the effect they have on the initial rate of peroxodisulphate ion formation in 5M-H2SO4 solution. The concentrations of the additives ranged from 10-4 to 10-2 mol dm-3. Both substances were found to increase current yields of peroxodisulphates as well as oxygen overpotential on the platinum anode. The additive concentration at which a maximum increase was achieved was about 1 . 10-2 mol dm-3 in both cases. Maximum current yields attained under the applied reaction conditions were, however, somewhat lower than those observed with an optimum addition of SCN-.

The effect of halides, pseudohalides, and some organic substances on the initial rate of peroxodisulphate formation

1981 ◽  
Vol 46 (11) ◽  
pp. 2809-2817 ◽  
Author(s):  
Jan Balej ◽  
Martin Kadeřávek
Keyword(s):  
Anodic Polarization ◽  
Initial Rate ◽  
Polarization Curves ◽  
Oxidation Products ◽  
Total Current ◽  
Organic Substances ◽  
Current Yield ◽  
Platinum Anode ◽  
Low Degree ◽  
Total Current Density

The effects of various additions of halides, pseudohalides and selected organic substances on the overall anodic polarization curves and the polarization curves of oxygen evolution and peroxodisulphate formation were examined under conditions of low degree of sulphate-to-peroxodisulphate conversion. Of the tested substances, SCN- and CN- ions, thiourea, urea and acetonitrile have proved to cause the greatest increase in the current yields of peroxodisulphate. However, the current yield varies as a function of the concentration of additive and the total current density, and goes through a maximum in both cases. The observed phenomena are discussed in terms of potential-dependent adsorption of additives or their oxidation products or intermediates on the oxidized surface of platinum anode.

scholarly journals New Kinetic Spectrophotometric Method for Determination of Fexofenadine Hydrochloride in Pharmaceutical Formulations

2014 ◽  
Vol 2014 ◽  
pp. 1-8 ◽  
Author(s):  
Safwan Ashour ◽  
Mouhammed Khateeb
Keyword(s):  
Spectrophotometric Method ◽  
Initial Rate ◽  
Pharmaceutical Preparations ◽  
Pharmaceutical Formulations ◽  
Fixed Time ◽  
Official Method ◽  
Reaction Conditions ◽  
Accuracy And Precision ◽  
Kinetic Spectrophotometric

A simple and sensitive kinetic spectrophotometric method was developed for the determination of fexofenadine hydrochloride in bulk and pharmaceutical preparations. The method is based on a kinetic investigation of the oxidation reaction of fexofenadine using alkaline potassium permanganate as an oxidizing agent at room temperature. The reaction is followed spectrophotometrically by measuring the increase of absorbance owing to the formation of manganate ion at 610 nm. The initial rate and fixed time (at 15 min) methods are utilized for construction of calibration graphs. All the reaction conditions for the proposed method have been studied. The linearity range was found to be 2.5–50.0 μg mL−1 with detection limit of 0.055 μg mL−1 for both initial rate and fixed time methods. The proposed method was applied successfully for the determination of fexofenadine in pharmaceutical formulations; the percentage recoveries were 99.98–101.96%. The results obtained were compared statistically with those obtained by the official method and showed no significant differences regarding accuracy and precision.

Undecagold labeling of tRNA

1991 ◽  
Vol 49 ◽  
pp. 44-45
Author(s):  
James F. Hainfeld ◽  
Kyra M. Alford ◽  
Mathias Sprinzl ◽  
Valsan Mandiyan ◽  
Santa J. Tumminia ◽  
...  
Keyword(s):  
High Resolution ◽  
Transmission Electron Micrograph ◽  
Anticodon Loop ◽  
Electron Micrograph ◽  
Reaction Conditions ◽  
Scanning Transmission Electron ◽  
Transmission Electron ◽  
Scanning Transmission

The undecagold (Au11) cluster was used to covalently label tRNA molecules at two specific ribonucleotides, one at position 75, and one at position 32 near the anticodon loop. Two different Au11 derivatives were used, one with a monomaleimide and one with a monoiodacetamide to effect efficient reactions.The first tRNA labeled was yeast tRNAphe which had a 2-thiocytidine (s2C) enzymatically introduced at position 75. This was found to react with the iodoacetamide-Aun derivative (Fig. 1) but not the maleimide-Aun (Fig. 2). Reaction conditions were 37° for 16 hours. Addition of dimethylformamide (DMF) up to 70% made no improvement in the labeling yield. A high resolution scanning transmission electron micrograph (STEM) taken using the darkfield elastically scattered electrons is shown in Fig. 3.

Lipoprotein Fractions and Antithrombin III Consumption During Clotting

1982 ◽  
Vol 47 (03) ◽  
pp. 236-238 ◽  
Author(s):  
J H Winter ◽  
B Bennett ◽  
F McTaggart ◽  
A S Douglas
Keyword(s):  
Blood Clotting ◽  
Antithrombin Iii ◽  
Initial Rate ◽  
Density Lipoprotein ◽  
Normal Subjects ◽  
Lipid Levels ◽  
Antithrombin Activity ◽  
Artery Disease ◽  
Immunological Assays ◽  
Total Triglyceride

SummaryPlasma and serum antithrombin levels were measured in functional (initial rate measurement) and immunological assays together with serum lipid levels in normal subjects and patients with coronary artery disease. Specific antithrombin activity in plasma showed a negative correlation with triglyceride levels. The consumption of antithrombin activity during blood clotting was negatively correlated with both serum total triglyceride and heparin precipitable lipoprotein and positively correlated with serum high density lipoprotein cholesterol. Different blood lipoprotein fractions may influence the activity of the antithrombin III molecule.

Platelet Adhesion to Subendothelium - Effect of Shear Rate, Hematocrit and Platelet Count on the Dynamic Equilibrium Between Platelets Adhering to and Detaching from the Surface

1985 ◽  
Vol 54 (04) ◽  
pp. 857-861 ◽  
Author(s):  
Andrea Remuzzi ◽  
Lucia Raffaella Languino ◽  
Vincenzo Costantini ◽  
Vincenzo Guardabasso ◽  
Giovanni de Gartano ◽  
...  
Keyword(s):  
Platelet Adhesion ◽  
Initial Rate ◽  
Dynamic Equilibrium ◽  
Dynamic Condition ◽  
Platelet Reactivity ◽  
Experimental Conditions ◽  
Platelet Suspension ◽  
Shear Rates ◽  
Platelet Concentration ◽  
Adhesion Rate

SummaryThe adherence of human 3H-adenine-labeled platelets to rat subendothelium was quantitated using a rotating probe device. Platelet adhesion increased in relation to the rotation time, reaching a plateau value in about 4-6 min without any further increase. A non-linear fitting analysis of experimental data allowed calculations of initial rate and plateau value of platelet adhesion. Increasing the shear rates (from 35 to 150 sec-1) or the hematocrit (from 10% to 40%), both the adhesion rate and the plateau value were increased. When different platelet concentrations were used the adhesion rate and the plateau calculated increased with platelet concentration. Different plateau values were obtained in the experimental conditions considered. This suggests that the plateau was not reached for the complete occupation of the subendothelial surface by the adherent platelets. Experiments using two different vessels rotated in the same platelet suspension or, viceversa, the same vessel rotated successively in two fresh platelet suspensions, showed that the plateau was not determined by reduced platelet reactivity. Rotating the same vessel first in radiolabeled platelets, until the plateau was reached, and secondly in non labeled platelets, or viceversa, showed that the plateau was indeed a dynamic condition where the number of platelets adhering and detaching reached equilibrium. These observations suggest that the platelet adhesion to subendothelium is the final equilibrium of two platelet fluxes, one adhering to the surface and another detaching from the surface.

A new method for quantifying the blocking of coated paperboard

TAPPI Journal ◽  
2010 ◽  
Vol 9 (5) ◽  
pp. 29-35 ◽  
Author(s):  
PAULINE SKILLINGTON ◽  
YOLANDE R. SCHOEMAN ◽  
VALESKA CLOETE ◽  
PATRICE C. HARTMANN
Keyword(s):  
Surface Roughness ◽  
Fatty Acid ◽  
Surface Energy ◽  
Film Thickness ◽  
External Factors ◽  
Additive Concentration ◽  
Pressure Surface ◽  
Fatty Acid Amides ◽  
Coated Surfaces ◽  
Definite Period

Blocking is undesired adhesion between two surfaces when subjected to pressure and temperature constraints. Blocking between two coated paperboards in contact with each other may be caused by inter-diffusion, adsorption, or electrostatic forces occurring between the respective coating surfaces. These interactions are influenced by factors such as the temperature, pressure, surface roughness, and surface energy. Blocking potentially can be reduced by adjusting these factors, or by using antiblocking additives such as talc, amorphous silica, fatty acid amides, or polymeric waxes. We developed a method of quantifying blocking using a rheometer. Coated surfaces were put in contact with each other with controlled pressure and temperature for a definite period. We then measured the work necessary to pull the two surfaces apart. This was a reproducible way to accurately quantify blocking. The method was applied to determine the effect external factors have on the blocking tendency of coated paperboards, i.e., antiblocking additive concentration, film thickness, temperature, and humidity.

EFFECTS OF ARGININE-, LYSINE- AND LEUCINE-VASOPRESSIN ON URINARY OSMOLALITY AND RATE OF URINE FLOW IN HYDRATED RATS AND DOGS

1959 ◽  
Vol XXXII (I) ◽  
pp. 134-141 ◽  
Author(s):  
Niels A. Thorn
Keyword(s):  
Arginine Vasopressin ◽  
Urine Osmolality ◽  
Urine Flow ◽  
The Other ◽  
Maximum Increase ◽  
Urinary Osmolality ◽  
Lysine Vasopressin

ABSTRACT Arginine-, lysine- and leucine-vasopressin, injected i. v. into hydrated rats or dogs caused different patterns of response in that urine osmolality fell much more slowly after the maximum increase following arginine-vasopressin, than after the other two preparations. Using 3 different parameters for antidiuretic response, arginine-vasopressin was somewhat more potent than leucine-vasopressin in both rats and dogs, considerably more potent than lysine-vasopressin in rats, and much more so in dogs.

Dimensionally-Controlled Hydrothermal Tm3+-doped Oxidic Nanocrystals and Their Photoluminescence Properties

2010 ◽  
Vol 1247 ◽  
Author(s):  
Rocío Calderón-Villajos ◽  
Carlos Zaldo ◽  
Concepción Cascales
Keyword(s):  
Single Crystals ◽  
Fluorescence Lifetimes ◽  
Photoluminescence Properties ◽  
Reaction Conditions ◽  
Hydrothermal Processes ◽  
Bulk Single Crystals ◽  
Template Free ◽  
Reaction Media

AbstractControlled reaction conditions in simple, template-free hydrothermal processes yield Tm-Lu2O3 and Tm-GdVO4 nanocrystals with well-defined specific morphologies and sizes. In both oxide families, nanocrystals prepared at pH 7 reaction media exhibit photoluminescence in ∼1.95 μm similar to bulk single crystals. For the lowest Tm3+ concentration (0.2 % mol) in GdVO4 measured 3H4 and 3F4 fluorescence lifetimes τ are very near to τrad.

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