Monte Carlo Modelling of Glass Dissolution: Comparison with Experiments

2000 ◽  
Vol 663 ◽  
Author(s):  
M. Lobanova ◽  
L. Maurer ◽  
P. Barboux ◽  
F. Devreux ◽  
Y. Minet
Keyword(s):  
Surface Layer ◽  
Volume Ratio ◽  
Protective Role ◽  
Glass Dissolution ◽  
Altered Surface ◽  
Alkali Oxides ◽  
Soluble Species ◽  
Glass Leaching ◽  
Solution Volume

ABSTRACTOne presents the results of numerical simulations of glass leaching. The glass is modelled as a random mixture of partly and totally soluble species, which represent silica, and boron or alkali oxides, respectively. It is shown that the dissolution rate and the thickness of the altered surface layer are strongly dependent on the glass composition, whereas the equilibrium solubility is not. The dependence of the layer thickness on the glass surface area to solution volume ratio is also emphasized. The protective role of the surface layer is shown to arise from its restructuring after the extraction of the soluble species. The simulation results are compared to an experimental study performed on series of SiO2-B2O3-Na2O glasses.

Glass Surface area to Solution Volume Ratio and its Implications to Accelerated Leach Testing

1982 ◽  
Vol 15 ◽  
Author(s):  
Larry R. Pederson ◽  
Charles Q. Buckwalter ◽  
Gary L. Mcvay ◽  
B. Lynn Riddle
Keyword(s):  
Solid State ◽  
Surface Area ◽  
Glass Surface ◽  
Volume Ratio ◽  
Leaching Tests ◽  
Soluble Glass ◽  
State Diffusion ◽  
Dissolved Silicon ◽  
Glass Leaching ◽  
Solution Volume

ABSTRACTLeaching tests of PNL 76–68 glass in deionized water have been performed using the standard MCC-l static leaching procedure but with varied glass surface area to solution volume ratios (SA/V). It was found that leaching could be strongly influenced by the SA/V ratio, due largely to an effect of silicon solubility limitations. The conclusion that solubility and not solid state diffusion is most important in regulating leaching rates is supported by (1) the similarities in depth profiles of all soluble glass components with none depleted to depths greater than that of silicon despite vastly different solid state diffusivities, and (2) the lack of dependence of leaching rates on reaction layer thicknesses. To more directly examine the influence of dissolved silicon on glass leaching rates, leaching tests were performed in silicic acid solutions and in two actual groundwaters. As expected, leaching rates of all soluble glass components were reduced by amounts roughly proportional to the silicon saturation fraction. Since solubility modifies leaching rates in all but very dilute solutions, short-term tests at high SA/V values can be used to predict solution concentrations for long-term tests at low SA/V values, although reaction layers formed are not of the same thickness. Glass leaching data for a range of leaching times and SA/V values can be represented by a single curve when plotted versus the product of SA/V and time. However, the use of SA/V variations may have limited usefulness in accelerated leach testing for multicomponent systems. Events such as silica colloid and certain alteration phase formations modify the above relationship.

Investigations on the Role of Surface Layers in HLW Glass Leaching

1985 ◽  
Vol 50 ◽  
Author(s):  
R. Conradt ◽  
H. Roggendorf ◽  
H. Scholze
Keyword(s):  
Corrosion Test ◽  
Protective Effects ◽  
Reaction Products ◽  
Surface Layers ◽  
Hydrothermal Conditions ◽  
Glass Dissolution ◽  
Salt Brine ◽  
Glass Leaching

AbstractA corrosion test series was performed to clarify the role of reaction product layers on the corrosion of a simulated HLW borosilicate glass in a salt brine under hydrothermal conditions. The layers were unprotective at 200°C. At 120°C, slight protective effects ocurred when the leachant contained dissolved reaction products. The consequence for the long term behaviour between 120 and 200°C is a constant glass dissolution rate.

The Functional Dependence of Leaching on The Surface Area-To-Solution Volume Ratio

1982 ◽  
Vol 15 ◽  
Author(s):  
Albert J. Machiels ◽  
Claudio Pescatore
Keyword(s):  
Surface Area ◽  
Functional Dependence ◽  
Mathematical Formulation ◽  
Volume Ratio ◽  
Computer Code ◽  
Point Of View ◽  
Theoretical Point ◽  
Leaching Experiments ◽  
Glass Leaching ◽  
Solution Volume

ABSTRACTThe effects of the surface area-to-solution volume ratio on waste glass leach rates are investigated from a theoretical point of view. Simple leach models are discussed first. Correlation variables to interpret the results of similar leaching experiments performed at different values of the surface area-to-solution volume ratio are obtained for static leach testing. For dynamic leaching conditions, the source term required for risk assessment is derived and its dependence on the leachant flow rate and leach specimen surface area is discussed. The findings are upheld by a more complex leach model, the mathematical formulation of which has been implemented in a computer code named LIX. When tested against actual PNL 76–68 glass leaching data, LIX shows excellent capabilities in reproducing the experimental evidence, in particular the effects of the surface area-to-solution volume ratio.

Protective role of peroxiredoxin-4 in heart failure

2020 ◽  
Vol 134 (1) ◽  
pp. 71-72
Author(s):  
Naseer Ahmed ◽  
Masooma Naseem ◽  
Javeria Farooq
Keyword(s):  
Heart Failure ◽  
Cardiac Fibroblasts ◽  
Protective Role ◽  
Oxidative Stress Markers ◽  
Stress Markers ◽  
Total Antioxidant ◽  
Galectin 3 ◽  
Consequent Increase ◽  
And Oxidative Stress

Abstract Recently, we have read with great interest the article published by Ibarrola et al. (Clin. Sci. (Lond.) (2018) 132, 1471–1485), which used proteomics and immunodetection methods to show that Galectin-3 (Gal-3) down-regulated the antioxidant peroxiredoxin-4 (Prx-4) in cardiac fibroblasts. Authors concluded that ‘antioxidant activity of Prx-4 had been identified as a protein down-regulated by Gal-3. Moreover, Gal-3 induced a decrease in total antioxidant capacity which resulted in a consequent increase in peroxide levels and oxidative stress markers in cardiac fibroblasts.’ We would like to point out some results stated in the article that need further investigation and more detailed discussion to clarify certain factors involved in the protective role of Prx-4 in heart failure.

Parenting Behaviors and Anxiety in Young Adults

2015 ◽  
Vol 36 (3) ◽  
pp. 170-176 ◽  
Author(s):  
Erin N. Stevens ◽  
Joseph R. Bardeen ◽  
Kyle W. Murdock
Keyword(s):  
Effortful Control ◽  
Parenting Behaviors ◽  
Protective Role ◽  
Anxiety Symptoms ◽  
Interactive Effects ◽  
Parental Overprotection ◽  
High Control ◽  
Development Of Anxiety ◽  
The Relationship

Parenting behaviors – specifically behaviors characterized by high control, intrusiveness, rejection, and overprotection – and effortful control have each been implicated in the development of anxiety pathology. However, little research has examined the protective role of effortful control in the relation between parenting and anxiety symptoms, specifically among adults. Thus, we sought to explore the unique and interactive effects of parenting and effortful control on anxiety among adults (N = 162). Results suggest that effortful control uniquely contributes to anxiety symptoms above and beyond that of any parenting behavior. Furthermore, effortful control acted as a moderator of the relationship between parental overprotection and anxiety, such that overprotection is associated with anxiety only in individuals with lower levels of effortful control. Implications for potential prevention and intervention efforts which specifically target effortful control are discussed. These findings underscore the importance of considering individual differences in self-regulatory abilities when examining associations between putative early-life risk factors, such as parenting, and anxiety symptoms.

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