A New Modelling of the Kinetics of Uranium Dioxide Oxidation in Air

2003 ◽  
Vol 807 ◽  
Author(s):  
L. Desgranges ◽  
C. Poinssot
Keyword(s):  
Weight Gain ◽  
Finite Difference ◽  
Uranium Dioxide ◽  
Oxygen Diffusion ◽  
Uranium Oxide ◽  
Fick’S Law ◽  
Fick's Law ◽  
Oxidation In Air ◽  
Kinetics Of

ABSTRACTA finite difference based modelling of the oxidation of uranium oxide is presented. This modelling involves only oxygen diffusion from the atmosphere into the solid and then inside the solid described with Fick's law. Some calculations performed with this modelling evidenced that the shape of the weight gain curves observed experimentally could be reproduced. This modelling is compared to the formula previously used to interpret the thermograms.

How large is the drop in PO2 between cytosol and mitochondrion?

1987 ◽  
Vol 252 (6) ◽  
pp. C583-C587 ◽  
Author(s):  
A. Clark ◽  
P. A. Clark ◽  
R. J. Connett ◽  
T. E. Gayeski ◽  
C. R. Honig
Keyword(s):  
Experimental Data ◽  
Experimental Evidence ◽  
Diffusion Coefficients ◽  
Oxygen Diffusion ◽  
Diffusion Theory ◽  
Heterogeneous Systems ◽  
Fick’S Law ◽  
Fick's Law ◽  
The Subject

The subject of this brief review is the size of the local drops in PO2 around consuming mitochondria. We show that large drops (several Torr or more) are in conflict with the predictions of basic diffusion theory, when one uses accepted values for relevant parameters. In particular, oxygen diffusion coefficients must be reduced by at least a factor of 10 below measured values to reconcile Fick's law with large PO2 drops. Experimental evidence offered for large drops is often ambiguous because of system heterogeneities. In those cases where tractable models of heterogeneous systems can be developed, the experimental data are consistent with drops in PO2 on the order of a few hundredths of a Torr between cytosol and mitochondrion.

scholarly journals On a numerical model for diffusion-controlled growth and dissolution of spherical precipitates

1998 ◽  
Vol 4 (2) ◽  
pp. 115-133 ◽  
Author(s):  
R. Van Keer ◽  
J. Kacur
Keyword(s):  
Numerical Model ◽  
Fick’S Law ◽  
Fick's Law ◽  
Diffusion Limited ◽  
Diffusion Controlled ◽  
The Matrix ◽  
Space Discretization ◽  
Element Technique ◽  
Domain Transformation ◽  
Kinetics Of

This paper deals with a numerical model for the kinetics of some diffusion-limited phase transformations. For the growth and dissolution processes in 3D we consider a single spherical precipitate at a constant and uniform concentration, centered in afinitespherical cell of a matrix, at the boundary of which there is no mass transfer, see also Asthana and Pabi [1] and Caers [2].The governing equations are the diffusion equation (2nd Fick's law) for the concentration of dissolved element in the matrix, with a known value at the precipitate-matrix interface, and the flux balans (1st Fick's law) at this interface. The numerical method, outlined for this free boundary value problem (FBP), is based upon a fixed domain transformation and a suitably adapted nonconforming finite element technique for the space discretization. The algorithm can be implemented on a PC. By numerous experiments the method is shown to give accurate numerical results.

scholarly journals Association between perinatal factors, genetic susceptibility to obesity and age at adiposity rebound in children of the EDEN mother–child cohort

2021 ◽  
Author(s):  
Aminata Hallimat Cissé ◽  
Sandrine Lioret ◽  
Blandine de Lauzon-Guillain ◽  
Anne Forhan ◽  
Ken K. Ong ◽  
...  
Keyword(s):  
Weight Gain ◽  
Genetic Susceptibility ◽  
Gestational Weight Gain ◽  
Gestational Age ◽  
Obesity Risk ◽  
Perinatal Factors ◽  
Gestational Weight ◽  
Adiposity Rebound ◽  
Kinetics Of

Abstract Background Early adiposity rebound (AR) has been associated with increased risk of overweight or obesity in adulthood. However, little is known about early predictors of age at AR. We aimed to study the role of perinatal factors and genetic susceptibility to obesity in the kinetics of AR. Methods Body mass index (BMI) curves were modelled by using mixed-effects cubic models, and age at AR was estimated for 1415 children of the EDEN mother–child cohort study. A combined obesity risk-allele score was calculated from genotypes for 27 variants identified by genome-wide association studies of adult BMI. Perinatal factors of interest were maternal age at delivery, parental education, parental BMI, gestational weight gain, maternal smoking during pregnancy, and newborn characteristics (sex, prematurity, and birth weight). We used a hierarchical level approach with multivariable linear regression model to investigate the association between these factors, obesity risk-allele score, and age at AR. Results A higher genetic susceptibility to obesity score was associated with an earlier age at AR. At the most distal level of the hierarchical model, maternal and paternal educational levels were positively associated with age at AR. Children born to parents with higher BMI were more likely to exhibit earlier age at AR. In addition, higher gestational weight gain was related to earlier age at AR. For children born small for gestational age, the average age at AR was 88 [±39] days lower than for children born appropriate for gestational age and 91 [±56] days lower than for children born large for gestational age. Conclusion The timing of AR seems to be an early childhood manifestation of the genetic susceptibility to adult obesity. We further identified low birth weight and gestational weight gain as novel predictors of early AR, highlighting the role of the intrauterine environment in the kinetics of adiposity.

Toxicology: Quantitative Aspects

1977 ◽  
Vol 17 (1) ◽  
pp. 37-52 ◽  
Author(s):  
D. C. J. Horncastle
Keyword(s):  
Experimental Error ◽  
Body Fluids ◽  
Fick’S Law ◽  
Fick's Law

Amounts of drugs found in body fluids and tissues at death are related to the time since ingestion and, within the limits of experimental error, obey Fick's law.

Higher-order hydrodynamics: Extended Fick’s Law, evolution equation, and Bobylev’s instability

2002 ◽  
Vol 116 (4) ◽  
pp. 1571-1584 ◽  
Author(s):  
David Jou ◽  
José Casas-Vázquez ◽  
Justino R. Madureira ◽  
Áurea R. Vasconcellos ◽  
Roberto Luzzi
Keyword(s):  
Evolution Equation ◽  
Higher Order ◽  
Fick’S Law ◽  
Fick's Law
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