Channel diffusion of sodium in a silicate glass

Jund, Philippe; Kob, Walter; Jullien, R.

doi:10.1103/physrevb.64.134303

Cited by 150 publications

(145 citation statements)

References 25 publications

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“…63,64 This behavior is illustrated in the insets of Figure 9. Both in main panels and in insets, arrows point to the direction of the increase of time.…”

Section: Resultsmentioning

confidence: 80%

Association of a Weakly Acidic Anti-Inflammatory Drug (Ibuprofen) with a Poly(Amidoamine) Dendrimer as Studied by Molecular Dynamics Simulations

Tanis

Karatasos

2009

J. Phys. Chem. B

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In this work, we report results from fully atomistic molecular dynamics simulations regarding the associative behavior of a third-generation poly(amidoamine) dendrimer with ibuprofen, a weakly acidic nonsteroidal anti-inflammatory drug, in aqueous solutions and at different pH conditions. Employing a combined static and dynamic approach, we describe the specifics of the complexation/encapsulation of the drug within the dendritic structure. In addition, information regarding the dynamic behavior is provided for the self-and the collective motion of the drug molecules. The detail afforded by the present molecular-level description of the relevant associative mechanisms (i.e., electrostatic complexation, hydrogen-bonding), provides a deeper insight for the interpretation of recent experimental findings regarding the behavior of dendrimer/ibuprofen systems in an aqueous environment.

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“…63,64 This behavior is illustrated in the insets of Figure 9. Both in main panels and in insets, arrows point to the direction of the increase of time.…”

Section: Resultsmentioning

confidence: 80%

Association of a Weakly Acidic Anti-Inflammatory Drug (Ibuprofen) with a Poly(Amidoamine) Dendrimer as Studied by Molecular Dynamics Simulations

Tanis

Karatasos

2009

J. Phys. Chem. B

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“…Moreover, the structure of damage, which influences macroscopic mechanical properties such as fracture toughness and lifetime, should then be linked to the glass composition and nanostructure [28,31,32,33]. Complementary analyses addressing the question of the chemical bonds on the fracture surface will also be performed.…”

Section: Discussionmentioning

confidence: 99%

Crack fronts and damage in glass at the nanometre scale

Marlière

Prades²,

Célarié³

et al. 2003

J. Phys.: Condens. Matter

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Abstract. We have studied the low speed fracture regime for different glassy materials with variable but controlled length scales of heterogeneity in a carefully mastered surrounding atmosphere. By using optical and atomic force microscopy (AFM) techniques we tracked in real-time the crack tip propagation at the nanometer scale on a wide velocity range (10 −3 − 10 −12 m/s and below). The influence of the heterogeneities on this velocity is presented and discussed. Our experiments reveal also -for the first time -that the crack progresses through nucleation, growth and coalescence of nanometric damage cavities within the amorphous phase. This may explain the large fluctuations observed in the crack tip velocities for the smallest values. This behaviour is very similar to what is involved, at the micrometric scale, in ductile fracture. The only difference is very likely due to the related length scales (nanometric instead of micrometric). Consequences of such a nano-ductile fracture mode observed at a temperature far below the glass transition temperature, T g , in glass is finally discussed.

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“…For a given ion engaged in bonds to oxygens, the sum of bond valences Table 2 Bond valences s(NdAO) in aluminoborosilicate glasses of this study (from EXAFS NdAO distances), expected bond valences s(MAO) for alkali and alkaline-earth ions (distances correspond to the addition of ionic radii, [6]) and proposed model for Nd and NBO coordination Glass and Cation type M CN [6] dM-O (Å , [6] must equal the ionic charge, and inversely, for given oxygen the sum of bond valences must be close to 2. Table 2 gives examples of bond valence calculation in the aluminoborosilicate glasses of this study.…”

Section: Bond Valence Model Of Nd Sites Inferred From the Exafs Nd-o mentioning

confidence: 99%

“…In the seven-oxide glass, these cations are Na + and Ca 2+ , but a great variety of neighboring cations must be assumed in the nuclear glass with complete composition. The RE 3+ , modifying cations and NBO's probably form depolymerized regions throughout the network, according to widely accepted models of glass structure [5,6], though their extent is matter of debate. To improve this model, we now investigate how the distribution of sites of the rare-earth ion may be dependent on the nature of the surrounding alkali and alkaline-earth ions.…”

Section: Introductionmentioning

confidence: 99%

Effect of alkali and alkaline-earth cations on the neodymium environment in a rare-earth rich aluminoborosilicate glass

Quintas

Majérus

Lenoir

et al. 2008

Journal of Non-Crystalline Solids

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The local structure around neodymium in an aluminoborosilicate glass bearing 3.6 mol% Nd 2 O 3 is studied by optical absorption spectroscopy and EXAFS at the Nd L III -and K-edges. The influence of the nature of alkalis (M + = Li + , Na + , K + , Rb + , Cs + ) and alkalineearths (M 2+ = Mg 2+ , Ca 2+ , Sr 2+ , Ba 2+ ) on the coordination sphere of Nd 3+ ions in the glass is particularly investigated. The Nd 3+ sites are well-defined with NdAO mean distances of 2.46 ± 0.03 Å , whatever the alkali and alkaline-earth ion type except Li + and Mg 2+ , for which glasses exhibit slightly more disordered Nd sites and longer NdAO distances (2.49 ± 0.03 Å ). Using bond valence considerations, a model is proposed for the Nd site, and consists in 7-8 non-bridging oxygens (NBO), every NBO being charge compensated by 2-3 alkalis and alkaline-earths. The NdAO mean distance is adjusted according to the mean field strength of these cations, to avoid overbonding of the NBO's. A glass series with varying Ca 2+ /Na + concentration ratio shows that Nd 3+ cations are able to maintain this average coordination site even at high alkaline-earth content.

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Channel diffusion of sodium in a silicate glass

Cited by 150 publications

References 25 publications

Association of a Weakly Acidic Anti-Inflammatory Drug (Ibuprofen) with a Poly(Amidoamine) Dendrimer as Studied by Molecular Dynamics Simulations

Association of a Weakly Acidic Anti-Inflammatory Drug (Ibuprofen) with a Poly(Amidoamine) Dendrimer as Studied by Molecular Dynamics Simulations

Crack fronts and damage in glass at the nanometre scale

Effect of alkali and alkaline-earth cations on the neodymium environment in a rare-earth rich aluminoborosilicate glass

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