Diffusion of Gases in Porous Solids. I. Theoretical Background and Experimental Method

1974 ◽  
Vol 52 (15) ◽  
pp. 2684-2691 ◽  
Author(s):  
K. R. Weller ◽  
N. S. Stenhouse ◽  
Harry Watts
Keyword(s):  
Diffusion Coefficients ◽  
Experimental System ◽  
Theoretical Background ◽  
Porous Solids ◽  
Diffusion Cell ◽  
Improved Method ◽  
Method Of Calculation ◽  
The Past ◽  
Concentration Changes

In the past, some authors have not defined the diffusion coefficient appropriate to their experimental system, consequently, valuable data have been lost. We discuss the various diffusion coefficients referred to all possible frames of reference in relation to the choice of a suitable experimental system for the determination of gaseous diffusion coefficients in porous media. A modified Ney and Armistead type diffusion cell is described with an improved method of calculation of results from continuously monitored concentration changes in the diffusion cell.

Diffusion of Methane and Chloromethanes in Air

1971 ◽  
Vol 49 (1) ◽  
pp. 74-77 ◽  
Author(s):  
M. Cowie ◽  
Harry Watts
Keyword(s):  
Carbon Tetrachloride ◽  
Diffusion Coefficients ◽  
Methylene Chloride ◽  
Methyl Chloride ◽  
Diffusion Cell ◽  
Infrared Spectrophotometry ◽  
Gaseous Diffusion ◽  
Simple Diffusion ◽  
Concentration Changes

The binary gaseous diffusion coefficients of air with methane, methyl chloride, methylene chloride, chloroform, and carbon tetrachloride at 298.2 °K and 1 atm have been determined. A simple diffusion cell was used, in which concentration changes of the diffusing gas were followed by infrared spectrophotometry.

Some Methodological Modifications of Determination of Diffusion Coefficients in Compacted Bentonite

2006 ◽  
Vol 932 ◽  
Author(s):  
Dušan Vopálka ◽  
Helena Filipská ◽  
Antonín Vokál
Keyword(s):  
Diffusion Coefficients ◽  
Effective Porosity ◽  
Diffusion Method ◽  
Dry Density ◽  
Diffusion Cell ◽  
Compacted Bentonite ◽  
Method Of Evaluation ◽  
Exclusion Effect ◽  
Positively Charged

ABSTRACTThe results of 3H, 36Cl and 137Cs diffusion experiments through compacted bentonite using a new design of diffusion cell and a new methodology of diffusion coefficients evaluation are presented. The diffusion cell was made from the stainless steel and enables to connect it directly to the input and/or output reservoirs without any tubing. The evaluation of diffusion coefficients utilizes a compartmental model developed in the environment of the GoldSim transport code. It enables to determine diffusion coefficients for various types of boundary conditions, including also input and output filters. The influence of the diffusion through filters on the determined values of both effective (De) and apparent (Da) diffusion coefficients was numerically demonstrated for the through diffusion method. This effect is most important for Da, the value of which would be underestimated using standard ways of evaluation for neutral and positively charged species, mainly in the case of high effective porosity.The comparison of standard and the newly developed method of evaluation of diffusion coefficients showed a significant influence of diffusion in filters for HTO. Contrary to the standard method of evaluation, the evaluation taking into account filters showed here no difference between total and effective porosity. The effect of filter resistance was negligible for Cl-, especially at high dry density of compacted bentonite, due to the anion exclusion effect. The numerical model developed enabled to determine Da values of Cs+ from the concentration change in the inlet reservoir.

scholarly journals Note: Determination of effective gas diffusion coefficients of stainless steel films with differently shaped holes using a Loschmidt diffusion cell

2010 ◽  
Vol 81 (4) ◽  
pp. 046104 ◽  
Author(s):  
N. G. C. Astrath ◽  
J. Shen ◽  
F. B. G. Astrath ◽  
J. Zhou ◽  
C. Huang ◽  
...  
Keyword(s):  
Stainless Steel ◽  
Diffusion Coefficients ◽  
Gas Diffusion ◽  
Diffusion Cell

Diffusion of Gases in Porous Solids. II. Diffusion of an Isotope Trace through Binary Gaseous Mixtures in a Porous Graphite

1974 ◽  
Vol 52 (15) ◽  
pp. 2692-2700
Author(s):  
K. R. Weller ◽  
N. S. Stenhouse ◽  
Harry Watts
Keyword(s):  
Diffusion Coefficients ◽  
Latin Squares ◽  
Diffusion Equations ◽  
Porous Solids ◽  
Statistical Experimental Design ◽  
Gaseous Mixtures ◽  
Porous Graphite ◽  
Xenon 133 ◽  
Model Diffusion

Diffusion coefficients of krypton-85 and xenon-133 through binary mixtures with He, Ne, Ar, Kr, and Xe permeating a porous graphite were measured. The statistical experimental design employing six 5 × 5 Latin squares permitted determination of the effects of gas type, mixture composition, and gas pressure. Five different cells were used and cell effects also determined. A regression equation which adequately correlated the experimental data was derived. This equation also correlated some literature data with better precision than did other model diffusion equations.

Transmission Electron Microscopy of Protein Macromolecules

1971 ◽  
Vol 29 ◽  
pp. 424-425
Author(s):  
Henry S. Slayter
Keyword(s):  
Biological Systems ◽  
Metal Vapor ◽  
Resolving Power ◽  
Electron Microscopic ◽  
Chemical Methods ◽  
Molecular Weights ◽  
The Past ◽  
Physical Chemical ◽  
Transmission Electron

Electron microscopic methods have been applied increasingly during the past fifteen years, to problems in structural molecular biology. Used in conjunction with physical chemical methods and/or Fourier methods of analysis, they constitute powerful tools for determining sizes, shapes and modes of aggregation of biopolymers with molecular weights greater than 50, 000. However, the application of the e.m. to the determination of very fine structure approaching the limit of instrumental resolving power in biological systems has not been productive, due to various difficulties such as the destructive effects of dehydration, damage to the specimen by the electron beam, and lack of adequate and specific contrast. One of the most satisfactory methods for contrasting individual macromolecules involves the deposition of heavy metal vapor upon the specimen. We have investigated this process, and present here what we believe to be the more important considerations for optimizing it. Results of the application of these methods to several biological systems including muscle proteins, fibrinogen, ribosomes and chromatin will be discussed.

SERUM TRIIODOTHYRONINE DETERMINATION BY SATURATION ANALYSIS

1973 ◽  
Vol 72 (4) ◽  
pp. 714-726 ◽  
Author(s):  
A. Burger ◽  
B. Miller ◽  
C. Sakoloff ◽  
M. B. Vallotton
Keyword(s):  
Ionic Strength ◽  
Limit Of Detection ◽  
Improved Method ◽  
Accuracy Of Measurement ◽  
Tracer Amount ◽  
The Mean ◽  
Physiological Values ◽  
Hyperthyroid Patients ◽  
Solvent Blank

ABSTRACT An improved method for the determination of serum triiodothyronine (T3) has been developed. After addition of a tracer amount of the hormone, T3 was extracted from 1 ml serum under conditions of pH and ionic strength which favoured T3 extraction (89%) over thyroxine (T4) extraction (58%). Chromatography of the extracted material on Sephadex LH-20 separated T3 completely from residual T4. The T3 eluate was dried, then re-dissolved in 0.5 ml NaOH 0.04 n. To 0.2 ml duplicate aliquots, a standard amount of TBG was added for the competitive protein analysis. After one hour incubation at 4°C, separation of bound from free T3 was achieved on small Sephadex G-25 columns. Overall recovery was 67 ± 10.8% and correction for the loss was made. The solvent blank was 37 ± 27 (sd) ng/100 ml. Accuracy of measurement of known quantities of T3 added to serum was 98.4%. The coefficient of variation within the assay was 6.2% and between the assays it was 11.4%. The limit of detection (0.1 ng) corresponded to a concentration of 25 ng/100 ml. T4 added to serum did not interfere with T3 determination until high non-physiological values were reached. The mean ± sd serum T3 in 54 euthyroid subjects was 153 ± 58 ng/100 ml and in 24 hyperthyroid patients it was 428 ±186 ng/100 ml; 4 out of the 24 hyperthyroid values were within 2 sd of the mean euthyroid group. All the values found in the euthyroid group were well above the limit of detection of the method.

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