scholarly journals Molecular Simulation of Tracer Diffusion and Self-Diffusion in Entangled Polymers

2020 ◽  
Vol 53 (12) ◽  
pp. 4649-4658
Author(s):  
Sachin Shanbhag ◽  
Zuowei Wang
Keyword(s):  
Molecular Simulation ◽  
Tracer Diffusion ◽  
Self Diffusion ◽  
Entangled Polymers

Self-diffusion of Ag+ and Na+ in molten Ca(NO3)2-KNO3

1972 ◽  
Vol 25 (8) ◽  
pp. 1613 ◽  
Author(s):  
BJ Welch ◽  
CA Angell
Keyword(s):  
Electrical Conductance ◽  
Ionic Species ◽  
Tracer Diffusion ◽  
Dilute Solution ◽  
Self Diffusion ◽  
Capillary Method ◽  
Arrhenius Temperature Dependence ◽  
Radio Tracer ◽  
Tracer Diffusion Coefficients ◽  
Arrhenius Temperature

In order to explore the behaviour of diffusing ionic species in a molten salt in which non-Arrhenius behaviour of other transport properties is established, the diffusivities in dilute solution of Ag+ and Na+ in 38.1 mol% Ca(NO3)2+ 61.9 mol% KNO3 have been measured. For both ions limited radio-tracer diffusion coefficients, determined using a diffusion-out-of-capillary method, are reported. D(Ag+) has also been measured by chronopotentiometry, by which means the range and reliability of the measurements were considerably extended. Chronopotentiometric and tracer data agree within expected errors of measurement. Both ionic diffusivities show a non-Arrhenius temperature dependence which is indistinguishable in magnitude from that of the electrical conductance of the solvent melt.

Lithium tracer diffusion in near stoichiometric LiNi0.5Mn1.5O4 cathode material for lithium-ion batteries

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Daniel Uxa ◽  
Harald Schmidt
Keyword(s):  
Cathode Material ◽  
Secondary Ion Mass Spectrometry ◽  
Lithium Ion ◽  
Tracer Diffusion ◽  
Side Reactions ◽  
Battery Materials ◽  
Self Diffusion ◽  
Thermally Activated ◽  
Average Grain Size ◽  
And Migration

Abstract The compound LiNi0.5Mn1.5O4 is used as novel cathode material for Li-ion batteries and represents a variant to replace conventional LiMn2O4. For a further improvement of battery materials it is necessary to understand kinetic processes at and in electrodes and the underlying diffusion of lithium that directly influences charging/discharging times, maximum capacities, and possible side reactions. In the present study Li tracer self-diffusion is investigated in polycrystalline sintered bulk samples of near stoichiometric LiNi0.5Mn1.5O4 with an average grain size of about 50–70 nm in the temperature range between 250 and 600 °C. For analysis, stable 6Li tracers are used in combination with secondary ion mass spectrometry (SIMS). The tracer diffusivities can be described by the Arrhenius law with an activation enthalpy of (0.97 ± 0.05) eV, which is interpreted as the sum of the formation and migration energy of a thermally activated Li vacancy.

Diffusion in hydrogel-supported phospholipid bilayer membranes

2013 ◽  
Vol 723 ◽  
pp. 352-373 ◽  
Author(s):  
Chih-Ying Wang ◽  
Reghan J. Hill
Keyword(s):  
Tracer Diffusion ◽  
Membrane Dynamics ◽  
The Self ◽  
Phospholipid Bilayer ◽  
Total Force ◽  
Membrane Thickness ◽  
Bilayer Membranes ◽  
Self Diffusion ◽  
Planar Membrane ◽  
Self Diffusion Coefficient

AbstractWe model a cylindrical inclusion (lipid or membrane protein) translating with velocity$U$in a thin planar membrane (phospholipid bilayer) that is supported above and below by Brinkman media (hydrogels). The total force$F$, membrane velocity, and solvent velocity are calculated as functions of three independent dimensionless parameters:$\Lambda = \eta a/ ({\eta }_{m} h)$,${\ell }_{1} / a$and${\ell }_{2} / a$. Here,$\eta $and${\eta }_{m} $are the solvent and membrane shear viscosities,$a$is the particle radius,$h$is the membrane thickness, and${ \ell }_{1}^{2} $and${ \ell }_{2}^{2} $are the upper and lower hydrogel permeabilities. As expected, the dimensionless mobility$4\mathrm{\pi} \eta aU/ F= 4\mathrm{\pi} \eta aD/ ({k}_{B} T)$(proportional to the self-diffusion coefficient,$D$) decreases with decreasing gel permeabilities (increasing gel concentrations), furnishing a quantitative interpretation of how porous, gel-like supports hinder membrane dynamics. The model also provides a means of inferring hydrogel permeability and, perhaps, surface morphology from tracer diffusion measurements.

scholarly journals The analysis of intermolecular interactions in concentrated hyaluronan solutions suggest no evidence for chain–chain association

2000 ◽  
Vol 350 (1) ◽  
pp. 329-335 ◽  
Author(s):  
Phillip GRIBBON ◽  
Boon Chin HENG ◽  
Timothy E. HARDINGHAM
Keyword(s):  
Fluorescence Recovery After Photobleaching ◽  
Hydrodynamic Radius ◽  
Hydrophobic Interactions ◽  
Lateral Diffusion ◽  
Tracer Diffusion ◽  
Dilute Solution ◽  
Concentrated Solutions ◽  
Chain Flexibility ◽  
Self Diffusion ◽  
Confocal Fluorescence

Confocal fluorescence recovery after photobleaching (confocal-FRAP) was used to examine the influence of electrolytes (NaCl, KCl, MgCl2, MnCl2 and CaCl2) on the network and hydrodynamic properties of fluoresceinamine-labelled hyaluronan (FA-HA) at concentrations up to 10mg/ml. Self and tracer lateral diffusion coefficients showed that in Ca2+ and Mn2+, FA-HA (830kDa) was more compact than in Mg2+, Na+ or K+. These results were correlated with changes in the hydrodynamic radius of HA, determined by multi-angle laser-light-scattering analysis in dilute solution, which was smaller in CaCl2 (36nm) than in NaCl (43nm). The permeability of more concentrated solutions of HA (< 10mg/ml) to FITC-dextran tracers (2000kDa) was higher in CaCl2. The properties of HA in urea (up to 6M) were investigated to test for hydrophobic interactions and also in ethanol/water (up to 62%, v/v). In both, there was reduced hydrodynamic size and increased permeability to FITC-dextran, suggesting increased chain flexibility, but it did not show the changes predicted if chain–chain association was disrupted by urea, or enhanced by ethanol. Oligosaccharides of HA (HA20–26) also had no effect on the self diffusion of high-molecular-mass FA-HA (830kDa) solutions, or on dextran tracer diffusion, showing that there were no chain–chain interactions open to competition by short-chain segments. The results suggest that the effects of electrolytes and solvent are determined primarily by their effect on HA chain flexibility, with no evidence for association between chain segments contributing significantly to the major properties.

Oxygen nonstoichiometry, defect structure and oxygen diffusion in the double perovskite GdBaCo2O6−δ

2014 ◽  
Vol 43 (42) ◽  
pp. 15937-15943 ◽  
Author(s):  
D. S. Tsvetkov ◽  
M. V. Ananjev ◽  
V. A. Eremin ◽  
A. Yu. Zuev ◽  
E. Kh. Kurumchin
Keyword(s):  
Diffusion Coefficient ◽  
Double Perovskite ◽  
Tracer Diffusion ◽  
Oxygen Nonstoichiometry ◽  
Tracer Diffusion Coefficient ◽  
Self Diffusion ◽  
Polarization Technique ◽  
Dc Polarization ◽  
Oxygen Tracer ◽  
Self Diffusion Coefficient

The values of the oxygen self-diffusion coefficient measured by the dc-polarization technique completely coincide with those of the oxygen tracer diffusion coefficient.

scholarly journals Composition Effect on Shrinkage of Hollow Binary Alloy Nanospheres

2009 ◽  
Vol 289-292 ◽  
pp. 665-672 ◽  
Author(s):  
Alexander V. Evteev ◽  
Elena V. Levchenko ◽  
Irina V. Belova ◽  
Graeme E. Murch
Keyword(s):  
Steady State ◽  
Binary Alloy ◽  
Kinetic Monte Carlo ◽  
Geometric Mean ◽  
Tracer Diffusion ◽  
Theoretical Description ◽  
Radial Dependence ◽  
Atomic Fraction ◽  
Steady State Condition ◽  
Self Diffusion

In this paper, a hollow random binary alloy nanosphere and initially homogeneous is considered under the approximation that the radial dependence of the vacancy formation free energy can be neglected. On the basis of a theoretical description and kinetic Monte Carlo simulations it is shown that the steady-state condition for the atomic components is not achievable during its shrinkage at any composition when the ratio of the tracer diffusion coefficients is not greater than two orders of magnitude. In the theoretical description, the dependence of the collapse time of the hollow random binary alloy nanosphere on the atomic fraction of the faster diffusing species at can be estimated by using the geometric mean of the ratios of the atomic fluxes at self-diffusion and steady-state. At the ratio of the atomic fluxes approaches the self-diffusion ratio as increases.

scholarly journals Erratum to: Overview of SIMS-Based Experimental Studies of Tracer Diffusion in Solids and Application to Mg Self-Diffusion

2014 ◽  
Vol 35 (6) ◽  
pp. 779-779
Author(s):  
Nagraj S. Kulkarni ◽  
Robert J. Bruce Warmack ◽  
Bala Radhakrishnan ◽  
Jerry L. Hunter ◽  
Yongho Sohn ◽  
...  
Keyword(s):  
Experimental Studies ◽  
Tracer Diffusion ◽  
Diffusion In Solids ◽  
Self Diffusion

High-temperature diffusion of oxygen in synthetic diopside measured by nuclear reaction analysis

1999 ◽  
Vol 63 (5) ◽  
pp. 673-686 ◽  
Author(s):  
L. Pacaud ◽  
J. Ingrin ◽  
O. Jaoul
Keyword(s):  
High Temperature ◽  
Nuclear Reaction ◽  
Diffusion Coefficients ◽  
Tracer Diffusion ◽  
Nuclear Reaction Analysis ◽  
Gas Mixture ◽  
Diffusion Study ◽  
Self Diffusion ◽  
Temperature Diffusion ◽  
Diffusion Profiles

AbstractWe have performed O self-diffusion experiments in synthetic diopside single crystals along the b-axis at temperatures ranging from 1473–1643 K, under controlled O partial pressure (10−11–10−2 atm). The 18O tracer diffusion was imposed by solid/gas exchange between 16O in diopside and 18O2-enriched argon-hydrogen-H2O gas mixture. Diffusion profiles of 18O were measured by Nuclear Reaction Analysis 18O (p,α) 15N. The diffusion coefficients are described by , with log D0(m2/s)=−9.2 ± 1.0 and E 310 ± 30 kJ/mol.Our results are in agreement with Ryerson and McKeegan's (1994) data and Farver's (1989) data along a direction perpendicular to the c direction. Experiments performed in a wide pO2 range show that D is independent of pO2.We observe no change in the diffusion regime up to 1643 K (i.e. 22 K prior to melting temperature). This result differs from the diffusion study of Ca in diopside by Dimanov and Ingrin (1995), where a strong enhancement of Ca mobility, attributed to an excess disorder in the Ca-sublattice, was observed above 1523 K. We conclude that O diffusion in diopside is not affected by this premelting phenomenon.

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