Hydrogenation of nitrogen oxide on platinum-carbon catalysts in acidic medium

1981 ◽  
Vol 46 (11) ◽  
pp. 2669-2675 ◽  
Author(s):  
Ivo Paseka
Keyword(s):  
Nitrogen Oxide ◽  
Acidic Medium ◽  
Diffusion Region ◽  
Acid Solutions ◽  
Experimental Conditions ◽  
Platinum Content ◽  
Kinetically Controlled ◽  
Partial Pressures ◽  
Carbon Catalysts

Hydrogenation of nitrogen oxide in acid solutions on Pt-C catalysts proceeds in dependence on experimental conditions either in purely diffusion region or in the diffusion and kinetically controlled region. The boundary between these two processes shifts to the higher ratio of NO to H2 partial pressures with increasing platinum content and decreasing intensity of agitation.

The content of nitric oxide and S-nitrosothiols in rats’ liver cells under the different supplementation of macronutrient

2020 ◽  
Vol 12 (2) ◽  
pp. 187-195
Author(s):  
Halyna Kopylchuk ◽  
Ivanna Nykolaichuk ◽  
Olesiia Kuziak
Keyword(s):  
Nitric Oxide ◽  
Nitrogen Oxide ◽  
Nitrosative Stress ◽  
Liver Cells ◽  
Oxide Content ◽  
Experimental Conditions ◽  
Before And After ◽  
Rat Liver Cells ◽  
Key Factor ◽  
Excessive Consumption

This paper presents studies of nitric oxide and low-molecular S-nitrosothiols in the mitochondrial and cytosolic fractions of the rats' liver under the conditions of, alimentary protein deprivation, consumption of excess sucrose content and combined action of two adverse factors. In order to model the low-protein diet of the animal for 28 days received an isocaloric diet containing 4.7% protein, 10% fat, 81,3% carbohydrates (starch – 37%, sucrose – 30%, cellulose – 5%) and was calculated in accordance with the recommendations of the American Institute of Nutrition. The high-sugar diet consisted of 14% protein, 10% fat, 72% carbohydrates (starch – 37%, sucrose – 30%, cellulose – 5%). The mitochondrial and cytosolic fraction of rat liver cells were obtained by the method of differential centrifugation. Nitrogen oxide content was assessed by a unified method by determining the NO2- content, which is a stable metabolite of nitric oxide. Since NO is inactivated into an oxidase reaction with the conversion into nitrite or nitrate that is quickly metabolized, the nitrogen oxide content was assessed by the change in NO2-. The concentration of S-nitrosothiols was recorded, respectively, by determining the concentration of nitrite anion before and after the addition of Hg2+ ions, which by modifying the S – N bonds catalyzes the release of S-nitrosyl thiols of nitric oxide. An increase in NO content in both hepatic subcellular fractions of the rats’ experimental groups compared to control values was found. However, a lack of protein in the diet (protein deficiency in the diet leads to an increase in nitric oxide levels in 3-4 times) can be considered as a key factor in the recorded changes in the mitochondria of the animals’ liver, while in the cytosol - excessive consumption of sucrose (3-5 times increase). Regarding the level of S-nitrosothiols, in the studied fractions, multidirectional changes in their concentration were found. Thus, an increase in the content of nitrosyl derivatives in the mitochondria of rat’s liver cells with a simultaneous decrease in their level in the cytosol indicates dysmetabolic disorders in the transport system and deposition of nitric oxide, which can lead to the development of nitrosative stress under the experimental conditions.

scholarly journals Methane-induced haemolysis of human erythrocytes

1995 ◽  
Vol 307 (2) ◽  
pp. 433-438 ◽  
Author(s):  
H Batliwala ◽  
T Somasundaram ◽  
E E Uzgiris ◽  
L Makowski
Keyword(s):  
Diffusion Rate ◽  
Human Erythrocytes ◽  
Experimental Conditions ◽  
Detergent Concentration ◽  
Partial Pressures ◽  
Temperature Diffusion ◽  
Wide Range ◽  
Gas Molecules ◽  
High Concentrations ◽  
Cell Leakage

Human erythrocytes were exposed to high concentrations of methane and nitrogen through the application of elevated partial pressures of these gas molecules. Cell leakage (haemolysis) was measured for cells exposed to these gases under a wide range of experimental conditions. Application of methane produces haemolysis at pressures far below the hydrostatic pressures known to disrupt membrane or protein structure. The effects of changes in buffer, temperature, diffusion rate and detergents were studied. Methane acts co-operatively with detergents to produce haemolysis at much lower detergent concentration than is required in the absence of methane or in the presence of nitrogen. At sufficiently high concentrations of methane, all cells are haemolysed. Increased temperature enhances the effect. Methane produces 50% haemolysis at a concentration of about 0.33 M compared with about 7.5 M methanol required for the same degree of haemolysis.

Effect of glycogen depletion on the ventilatory response to exercise

1983 ◽  
Vol 54 (2) ◽  
pp. 470-474 ◽  
Author(s):  
G. J. Heigenhauser ◽  
J. R. Sutton ◽  
N. L. Jones
Keyword(s):  
Muscle Glycogen ◽  
Power Output ◽  
Co2 Flux ◽  
Glycogen Depletion ◽  
Experimental Conditions ◽  
Co2 Output ◽  
Partial Pressures ◽  
End Tidal ◽  
Response To Exercise ◽  
Male Subjects

Five male subjects performed two graded exercise studies, one during control conditions and the other after reduction of muscle glycogen content by repeated maximum exercise and a high fat-protein diet. Reduction in preexercise muscle glycogen from 59.1 to 17.1 mumol X g-1 (n = 3) was associated with a 14% reduction in maximum power output but no change in maximum O2 intake; at any given power output O2 intake, heart rate, and ventilation (VE) were significantly higher, CO2 output (VCO2) was similar, and the respiratory exchange ratio was lower during glycogen depletion compared with control. The higher VE during glycogen depletion was associated with a higher VE/VCO2 ratio, lower end-tidal and mixed venous CO2 partial pressures, and higher blood pH than in the control studies. Changes in exercise VE accompanying glycogen depletion were not explained by changes in CO2 flux to the lungs suggesting that other factors served to modulate VE in these experimental conditions.

scholarly journals Preliminary results on the effect of power ultrasound on nitrogen oxide and dioxide atmosphere in nitric acid solutions

2001 ◽  
Vol 8 (3) ◽  
pp. 175-181 ◽  
Author(s):  
Ph. Moisy ◽  
I. Bisel ◽  
F. Genvo ◽  
F. Rey-Gaurez ◽  
L. Venault ◽  
...  
Keyword(s):  
Nitric Acid ◽  
Nitrogen Oxide ◽  
Acid Solutions ◽  
Power Ultrasound ◽  
Preliminary Results ◽  
Nitric Acid Solutions

A preliminary study of the release of platinum and palladium from metallic particles in the surface environment by organic acids: relevance to weathering of particles from vehicle exhaust catalysts

2005 ◽  
Vol 69 (5) ◽  
pp. 687-693 ◽  
Author(s):  
J. F. W. Bowles ◽  
A. P. Gize
Keyword(s):  
Experimental Work ◽  
Acid Solutions ◽  
Vehicle Exhaust ◽  
Experimental Conditions ◽  
Metallic Particles ◽  
Organic Complexes ◽  
Exhaust Catalysts ◽  
Platinum Group Minerals ◽  
Apparent Solubility ◽  
Platinum Group

AbstractStudies of the weathering of platinum-group minerals in natural deposits have indicated that the platinum-group elements (PGE) can be mobilized under appropriate conditions and have sufficient solubility to move into solution. Although inorganic chemistry provides feasible mechanisms under the extreme conditions encountered in laterites it appears likely that PGE-organic complexes offer a more convincing explanation of the apparent solubility. Experimental work undertaken to illustrate the organic processes and the reaction timescale examined various reactions including those between Pt and Pd foils and humic and fulvic acid solutions. These reactions appear pertinent to those that may occur between the PGE particles ejected by vehicle exhaust catalysts and the natural environment.The experimental work produced up to 195 μ/l Pt and 102 μ/l Pd in humic acid solutions exposed to the metal foils for about a year at room temperature. The experimental conditions can be compared to those encountered in roadside drainage supplied with PGE particles and decaying vegetation.Consideration of the possible health effects of the PGE from the particles ejected by vehicle exhaust catalysts has centred on inhalation of the particles or absorption through the skin. Intake from drinking water or from food produced using PGE-bearing water should now also be investigated. Due to the variety of organic compounds produced by decaying vegetation the identity of the PGE-organic products is not yet known so their toxicity cannot be estimated.

scholarly journals Simple Atomic Absorption Spectroscopic and Spectrophotometric Methods for Determination of Pioglitazone Hydrochloride and Carvedilol in Pharmaceutical Dosage Forms

2014 ◽  
Vol 2014 ◽  
pp. 1-17 ◽  
Author(s):  
Afaf A. Abdelmonem ◽  
Gamal H. Ragab ◽  
Hisham Hashem ◽  
Eman A. Bahgat
Keyword(s):  
Atomic Absorption ◽  
Acidic Medium ◽  
Methylene Chloride ◽  
Ion Pair ◽  
Fast Green ◽  
Experimental Conditions ◽  
Pharmaceutical Dosage Forms ◽  
Spectrophotometric Methods ◽  
Orange G

This study represents simple atomic absorption spectroscopic and spectrophotometric methods for determination of pioglitazone hydrochloride (PGZ-HCl) and carvedilol (CRV) based on formation of ion-pair associates between drugs and inorganic complex, bismuth(III) tetraiodide (Method A) and between drugs and organic acidic dyes, fast green and orange G (Method B). Method A is based on formation of ion-pair associate between drugs and bismuth(III) tetraiodide in acidic medium to form orange-red ion-pair associates, which can be quantitatively determined by two different procedures. The formed ion-pair associate is extracted by methylene chloride, dissolved in acetone, dried, and then decomposed by hydrochloric acid, and bismuth content is determined by direct atomic absorption spectrometric technique (Procedure 1) or extracted by methylene chloride, dissolved in acetone, and quantified spectrophotometrically at 490 nm (Procedure 2). Method B is based on formation of ion-pair associate between drugs and either fast green dye or orange G dye in acidic medium to form ion-pair associates. The formed ion-pair associate is extracted by methylene chloride and quantified spectrophotometrically at 630 nm (for fast green dye method) or 498 nm (for orange G dye method). Optimal experimental conditions have been studied. Both methods are applied for determination of the drugs in tablets without interference.

Etude cinétique des systèmes Cu(II)•Adénosine et Cu(II)•D-Ribose

1972 ◽  
Vol 50 (19) ◽  
pp. 3117-3123 ◽  
Author(s):  
G. Boivin ◽  
M. Zador
Keyword(s):  
Kinetic Parameters ◽  
Acidic Medium ◽  
Temperature Jump ◽  
Strong Acid ◽  
Basic Medium ◽  
Stopped Flow ◽  
Acid Solutions ◽  
Flow Method ◽  
Kinetics Of ◽  
Adenine Base

The kinetics of the formation and dissociation of Cu(II) complexes of adenosine have been determined in acidic and basic medium. In acidic medium, the complex is formed between the Cu(II) and the adenine base and the kinetic parameters have been obtained in this case using a temperature jump method. In basic medium, only the dissociation of the complexes could be studied by a stopped-flow method, by addition of EDTA or strong acid solutions. In these complexes, Cu(II) is bridged with ribose hydroxyls. Finally, D-ribose has also been studied for comparison in the same conditions. The mechanism of these reactions is discussed.

scholarly journals Assessment of Sieverts Law Assumptions and ‘n’ Values in Palladium Membranes: Experimental and Theoretical Analyses

Membranes ◽  
2021 ◽  
Vol 11 (10) ◽  
pp. 778
Author(s):  
Abdulrahman Alraeesi ◽  
Tracy Gardner
Keyword(s):  
Concentration Polarization ◽  
Hydrogen Permeation ◽  
Pure Hydrogen ◽  
Hydrogen Purification ◽  
Hydrogen Transport ◽  
Experimental Conditions ◽  
Fixed Temperature ◽  
Hydrogen Flux ◽  
Partial Pressures ◽  
The Difference

Palladium and palladium alloy membranes are superior materials for hydrogen purification, removal, or reaction processes. Sieverts’ Law suggests that the flux of hydrogen through such membranes is proportional to the difference between the feed and permeate side partial pressures, each raised to the 0.5 power (n = 0.5). Sieverts’ Law is widely applied in analyzing the steady state hydrogen permeation through Pd-based membranes, even in some cases where the assumptions made in deriving Sieverts’ Law do not apply. Often permeation data are fit to the model allowing the pressure exponent (n) to vary. This study experimentally assessed the validity of Sieverts’ Law as hydrogen was separated from other gases and theoretically modelled the effects of pressure and temperature on the assumptions and hence the accuracy of the 0.5-power law even with pure hydrogen feed. Hydrogen fluxes through Pd and Pd-Ag alloy foils from feed mixtures (5–83% helium in hydrogen; 473–573 K; with and without a sweep gas) were measured to study the effect of concentration polarization (CP) on hydrogen permeance and the applicability of Sieverts’ Law under such conditions. Concentration polarization was found to dominate hydrogen transport under some experimental conditions, particularly when feed concentrations of hydrogen were low. All mixture feed experiments showed deviation from Sieverts’ Law. For example, the hydrogen flux through Pd foil was found to be proportional to the partial pressure difference (n ≈ 1) rather than being proportional to the difference in the square root of the partial pressures (n = 0.5), as suggested by Sieverts’ Law, indicating the high degree of concentration polarization. A theoretical model accounting for Langmuir adsorption with temperature dependent adsorption equilibrium coefficient was made and used to assess the effect of varying feed pressure from 1–136 atm at fixed temperature, and of varying temperature from 298 to 1273 K at fixed pressure. Adsorption effects, which dominate at high pressure and at low temperature, result in pressure exponents (n) values less than 0.5. With better understanding of the transport steps, a qualitative analysis of literature (n) values of 0.5, 0.5 < n < 1, and n > 1, was conducted suggesting the role of each condition or step on the hydrogen transport based on the empirically fit exponent value.

scholarly journals Kinetics and Mechanism of Oxidation of Metformin Hydrochloride by Hexamolybdocobaltate(III) in Acidic Medium

2020 ◽  
Vol 33 (1) ◽  
pp. 15-20
Author(s):  
J.D. SAWANT ◽  
K.K. PATIL ◽  
G.S. GOKAVI
Keyword(s):  
Free Radical ◽  
Ir Spectra ◽  
Oxidation Product ◽  
Acidic Medium ◽  
High Performance ◽  
Direct Electron Transfer ◽  
Metformin Hydrochloride ◽  
Experimental Conditions ◽  
Rate Of Reaction ◽  
Ft Ir

The oxidation of metformin hydrochloride by Anderson-Evans type hexamolybdocobaltate(III) anion was investigated under pseudofirst- order condition in acidic medium at 298 K. The rate of reaction is accelerated by increase in the concentration of H+ ion. The decrease in the reaction rate with increase in the concentration of the oxidant [H6CoMo6O24]3- anion and added molybdate ion kinetically indicate existence of the prior equilibria between various forms of the oxidant. In present study, the oxidant exists in monomers [H6CoMo6O24]3- anion, [H5CoMo5O20]2- anion and dimer [H4Co2Mo10O38]6- forms between the pH 2 and 1. The active oxidant species is [H5CoMo5O20]2- anion. Under experimental conditions, the reaction involves direct electron-transfer from metformin center to oxidant anion generating free radical in rate determining step. The fast hydrolysis of formed free radical in presence of second oxidant molecule leads to formation of carbonyl imino functional group in the oxidation product. The ionic strength and solvent polarity had no significant effect on the rate of reaction. FT-IR spectra of metformin and its oxidation product sample were recorded and analyzed. The FT-IR spectra show the change in frequency of the functional groups of oxidation product than that of the pure MET. The formation of oxidation product was confirmed by high performance liquid chromatography associated with electron impact mass spectroscopy (LC/EI-MS). Thermodynamic parameters are evaluated by temperature variation kinetic data and are in support of the proposed mechanism. The probable mechanism is proposed leading to complicated rate law as a result of involvement of prior equillibria between various forms of the oxidant.

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