Strain Gradient Influence on Diffusion Coefficients of Deuterium in Absorption and Desorption of Deuterium in Pd81Pt19 Membrane

2003 ◽  
Vol 68 (6) ◽  
pp. 1046-1054 ◽  
Author(s):  
Danuta Dudek
Keyword(s):  
Activation Energy ◽  
Strain Gradient ◽  
Diffusion Coefficients ◽  
Volumetric Method ◽  
Initial Content ◽  
Activation Energy Of Diffusion

The diffusion of deuterium through a Pd81Pt19 membrane was investigated. At six temperatures in the range 278.2-328.2 K the diffusion coefficients were determined by breakthrough method for the membrane with no initial content of deuterium. The determined activation energy of diffusion of deuterium equals E = 26.4 kJ/mol. The solubility of deuterium in Pd81Pt19 alloy at 278.2 K was measured by volumetric method. The influence of self-stresses on diffusion of deuterium was investigated by determination of diffusion coefficients for the Pd81Pt19 membrane with different initial contents of deuterium at 278.2 K.

scholarly journals Diffusion Coefficients of n-Alkanes and 1-Alcohols in Polyethylene Naphthalate (PEN)

2019 ◽  
Vol 2019 ◽  
pp. 1-9
Author(s):  
Johann Ewender ◽  
Frank Welle
Keyword(s):  
Activation Energy ◽  
Data Storage ◽  
Diffusion Coefficients ◽  
Food Packaging ◽  
Light Emitting Diode ◽  
Preexponential Factor ◽  
Barrier Properties ◽  
Molecular Volume ◽  
Polyethylene Naphthalate ◽  
Activation Energy Of Diffusion

Polyethylene naphthalate (PEN) is a polyester polymer with well-known good barrier properties. PEN had been used in the food packaging area till 2012 especially as refillable bottles for soft drinks, juices, and beer. Now, PEN is mainly used in technical applications, e.g., for data storage tapes and organic light-emitting diode (OLED) applications. The aim of the study was the determination of the diffusion coefficients of organic molecules (n-alkanes, 1-alcohols) in PEN. Diffusion and partition coefficients were determined from the lag times of the permeation process of the permeants through a commercial 12 μm biaxial-oriented PEN film. In addition, activation energies of diffusion EA were calculated according to the Arrhenius approach. The activation energy of diffusion EA follows a correlation with the molecular volume V of the investigated permeants. In addition, the preexponential factor D0 follows a correlation with the activation energy of diffusion EA. The results of this study for PEN (e.g., EA, DP) were compared to literature data on PET.

Oxygen diffusion in amorphous and partially crystalline gallium oxide

2019 ◽  
Vol 21 (8) ◽  
pp. 4268-4275 ◽  
Author(s):  
Alexandra von der Heiden ◽  
Manuel Bornhöfft ◽  
Joachim Mayer ◽  
Manfred Martin
Keyword(s):  
Activation Energy ◽  
Diffusion Coefficients ◽  
Low Temperatures ◽  
Oxygen Diffusion ◽  
Gallium Oxide ◽  
Tracer Diffusion ◽  
Tof Sims ◽  
Tracer Diffusion Coefficients ◽  
Oxygen Tracer

We established a TTT diagram of crystallisation of gallium oxide. Determination of oxygen tracer diffusion coefficients by IEDP/ToF-SIMS allowed us to access the activation energy for amorphous GaO1.5 at low temperatures.

scholarly journals PENENTUAN ISI AWAL MINYAK DITEMPAT DENGAN MENGGUNAKAN METODEMATERIAL BALANCE DAN VOLUMETRIK PADA RESERVOIR ADZ

2019 ◽  
Vol 3 (2) ◽  
pp. 87
Author(s):  
Dikky Fathurochman Sidiq ◽  
Lestari Said
Keyword(s):  
Material Balance ◽  
Volumetric Method ◽  
Balance Method ◽  
Bubble Point ◽  
Oil Reserves ◽  
Bubble Point Pressure ◽  
Point Pressure ◽  
Initial Content ◽  
Material Balance Method

<p>Determination of the initial oil content of a reservoir starts from exploration activities. In the initial stage, the determination of the initial oil reserves is determined. This aims to determine whether the project can be profitable for the company or not. Over time the determination of the initial contents of the oil continues to be carried out to improve the accuracy of calculations using the material balance method.<br />In the reservoir "ADZ" the type of reservoir is an undersaturated reservoir. This is because the initial pressure in 1980 was 2762.74 psia, while the bubble point pressure was 1625.8 psia. Until 2015 this reservoir was still above the bubble point pressure with a pressure of 1783.55 psia, this reservoir also had no gas cap in the initial conditions. The drive mechanism that works on this field is the solution for the gas drive.<br />Calculation of the initial content of oil in this final project uses 4 methods, namely volumetric method, material balance method, straight line, and Mbal software. Using the volumetric method, the initial oil reserves obtained at the place amounted to 174063462 STB, while the calculation of the initial oil reserves in place using the material balance method was 176497285 STB. The percentage difference in the initial content of oil between the methods is &lt;5%.</p>

The Calculation of Turbulent Diffusion Coefficients in Aquatic Ecosystems

2019 ◽  
Vol 70 (11) ◽  
pp. 3903-3907
Author(s):  
Galina Marusic ◽  
Valeriu Panaitescu
Keyword(s):  
Transport Equation ◽  
Turbulent Diffusion ◽  
Diffusion Coefficients ◽  
Aquatic Ecosystems ◽  
Specific Area ◽  
Left Bank ◽  
The Right ◽  
Prut River

The paper deals with the issues related to the pollution of aquatic ecosystems. The influence of turbulence on the transport and dispersion of pollutants in the mentioned systems, as well as the calculation of the turbulent diffusion coefficients are studied. A case study on the determination of turbulent diffusion coefficients for some sectors of the Prut River is presented. A new method is proposed for the determination of the turbulent diffusion coefficients in the pollutant transport equation for specific sectors of a river, according to the associated number of P�clet, calculated for each specific area: the left bank, the right bank and the middle of the river.

Development of HPLC Method for the Purity Test by Design of Experiments and Determination of Activation Energy of Hydrolytic Degradation Reactions of Sofosbuvir

2020 ◽  
Vol 16 (7) ◽  
pp. 976-987
Author(s):  
Jakub Petřík ◽  
Jakub Heřt ◽  
Pavel Řezanka ◽  
Filip Vymyslický ◽  
Michal Douša
Keyword(s):  
Activation Energy ◽  
Design Of Experiments ◽  
Mobile Phase ◽  
Hydrolytic Degradation ◽  
Isoconversional Method ◽  
Hplc Method ◽  
Organic Modifier ◽  
Calculation Methods ◽  
Degradation Reactions

Background: The present study was focused on the development of HPLC method for purity testing of sofosbuvir by the Design of Experiments and determination of the activation energy of hydrolytic degradation reactions of sofosbuvir using HPLC based on the kinetics of sofosbuvir degradation. Methods: Following four factors for the Design of Experiments were selected, stationary phase, an organic modifier of the mobile phase, column temperature and pH of the mobile phase. These factors were examined in two or three level experimental design using Modde 11.0 (Umetrics) software. The chromatographic parameters like resolution, USP tailing and discrimination factor were calculated and analysed by partial least squares. The chromatography was performed based on Design of Experiments results with the mobile phase containing ammonium phosphate buffer pH 2.5 and methanol as an organic modifier. Separation was achieved using gradient elution on XBridge BEH C8 at 50 °C and a flow rate of 0.8 mL/min. UV detection was performed at 220 nm. The activation energy of hydrolytic degradation reactions of sofosbuvir was evaluated using two different calculation methods. The first method is based on the slope of dependence of natural logarithm of the rate constant on inverted thermodynamic temperature and the second approach is the isoconversional method. Results and Conclusion: Calculated activation energies were 77.9 ± 1.1 kJ/mol for the first method and 79.5 ± 3.2 kJ/mol for the isoconversional method. The results can be considered to be identical, therefore both calculation methods are suitable for the determination of the activation energy of degradation reactions.

Electroreduction of Cr(VI) from solutions of bifunctional alcohols

1989 ◽  
Vol 54 (10) ◽  
pp. 2638-2643
Author(s):  
David I. Balanchivadze ◽  
Tamara R. Chelidze ◽  
Jondo J. Japaridze
Keyword(s):  
Activation Energy ◽  
Ethylene Glycol ◽  
Electrode Surface ◽  
Frequency Factor ◽  
Limiting Current ◽  
Factor Log ◽  
Standard Rate ◽  
Standard Rate Constant ◽  
Chromate Ion ◽  
Activation Energy Of Diffusion

The effect of bifunctional alcohols ethylene glycol (EG) and 1,2-propylene glycol (1,2 PG) on the kinetic parameters for the irreversible chromate ion reduction were investigated by polarographic and coulometric methods of analysis. The electroreduction of chromate ion in neutral bifunctional alcohol solutions proceeds according to the scheme: Cr(VI)–Cr(III)–Cr(II) and the values of the standard rate constant k*0 decrease in the order H2O > EG > 1,2 PG. The values of real activation energy, Q, activation energy of diffusion, QD, and frequency factor log A° have been calculated. The obtained values of QD as well as Q proved the diffusion nature of limiting current. The values of the frequency factor log A° decrease in the order H2O > EG > 1,2 PG, which points to a less favourable orientation of the electroactive ions at the electrode surface in glycols.

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