Determination of the apparent diffusion constants in water containing granular solids

Author(s):  
H.A. Das ◽  
H.A. Van der Sloot ◽  
G.J. De Groot ◽  
R.C.H. Steneker
1929 ◽  
Vol 12 (4) ◽  
pp. 543-554 ◽  
Author(s):  
John H. Northrop ◽  
M. L. Anson

A method is described for determining the diffusion coefficient of solutes by determining the rate of passage of the solute through a thin porous membrane between two solutions of different concentration. The method has been used to determine the diffusion coefficient of carbon monoxide hemoglobin. This was found to be 0.0420 ± 0.0005 cm.2 per day at 5°C. The molecular weight of carbon monoxide hemoglobin calculated by means of Einstein's equation from this quantity is 68,600 ± 1,000.


Author(s):  
Rania Sobhy Abou Khadrah ◽  
Mohamed F. Dawoud ◽  
Ashraf Ali Abo-Elsafa ◽  
Amr M. Elkilany

Abstract Background T2 mapping and DWI are newly quantitated method for disk degeneration assessment; they were used in the determination of an early stage of intervertebral disk degeneration. T2 mapping was quantitatively sensitive for detecting the early stage and aging-related changes in intervertebral disk degeneration. Furthermore, T2 mapping and apparent diffusion coefficient values (ADC) in lumbar intervertebral disks indirectly correlated with the Pfirrmann grades in IVDD and age-related disk degeneration. The aim of this study is to evaluate the sensitivity of T2 mapping and apparent diffusion coefficient in the determination of an early stage of intervertebral disk degeneration. Results T2 relaxometry values were found to decrease with the increased disk degeneration except in grade V where it was found to be increased again. There was a negative correlation between T2 values and semi-quantitative grading (Pfirrmann Grading) of disk degeneration and T2 values were significantly different when comparing grade I to V. A T2 value of nucleus pulposus (NP) was more sensitive than annulus fibrosus (AF) and entire of the disk. ADC values were found to decrease with the increased degree of disk degeneration; there was a weakly significant negative correlation between age and T2 mapping values, ADC values of nucleus pulposus, and entire of disk. Conclusion T2 mapping was significantly different when comparing grade I to V while ADC value had a significant weak negative correlation with age, so T2 mapping and to a little extent ADC can be used for quantitative analysis of early disk generation seeking for early diagnosis and better management.


1980 ◽  
Vol 3 ◽  
Author(s):  
D. Wolf

ABSTRACTThe effect of atomic and molecular motions on the NMR free-induction decay (FID) and lineshape is investigated theoretically in the intermediate temperature range in which the NMR line is only partially narrowed. It is shown that the FID may be decomposed into the weighted sum of a rigid-lattice (background) contribution and an exponentially decaying part containing all the information on the diffusive or reorientational motions in the crystal in terms of the spin-spin relaxation time T2.


Science ◽  
1950 ◽  
Vol 112 (2921) ◽  
pp. 757-758 ◽  
Author(s):  
L. A. Walker

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