scholarly journals Surface diffusion of long chainlike molecules: The role of memory effects and stiffness on effective diffusion barriers

2000 ◽  
Vol 112 (10) ◽  
pp. 4731-4738 ◽  
Author(s):  
T. Hjelt ◽  
I. Vattulainen
Keyword(s):  
Surface Diffusion ◽  
Effective Diffusion ◽  
Diffusion Barriers ◽  
Memory Effects

scholarly journals Considerations on Temperature Dependent Effective Diffusion and Permeability of Natural Clays

Materials ◽  
2021 ◽  
Vol 14 (17) ◽  
pp. 4942
Author(s):  
Florian Wesenauer ◽  
Christian Jordan ◽  
Mudassar Azam ◽  
Michael Harasek ◽  
Franz Winter
Keyword(s):  
Surface Diffusion ◽  
Effective Diffusion ◽  
Diffusion Chamber ◽  
Model Fit ◽  
Temperature Dependent ◽  
Gaseous Mixtures ◽  
Thermochemical Processes ◽  
O2 Diffusion ◽  
Natural Clays

A series of porous clay samples prepared at different pretreatment temperatures have been tested in a diffusion chamber. Diffusivity and permeability were examined in a temperature range from ambient to 900 °C. Gaseous mixtures of O2, CO2, and N2 have been applied, as these species are the relevant gases in the context of clay brick firing and similar thermochemical processes. Diffusive transport characteristics have been determined by means of the mean transport-pore model, and permeability has been evaluated by Darcy’s law. CO2 diffusivity increased strongly with temperature, whereas O2 diffusion was limited to a certain level. It is proposed that one should consider CO2 surface diffusion in order to explain this phenomenon. The diffusion model was expanded and surface diffusion was included in the model equation. The results of the model fit reflected the important role of incorporated carbonates of the clay foundation in gas-phase (molecular or Knudsen) diffusivity. CO2 surface diffusion was observed to exhibit similar coefficients for two different investigated clays, and is therefore indicated as a property of natural clays. Permeability showed a progressive rise with temperature, in line with related literature.

scholarly journals On the role of surface diffusion in determining the shape or morphology of noble-metal nanocrystals

2013 ◽  
Vol 110 (17) ◽  
pp. 6669-6673 ◽  
Author(s):  
X. Xia ◽  
S. Xie ◽  
M. Liu ◽  
H.-C. Peng ◽  
N. Lu ◽  
...  
Keyword(s):  
Surface Diffusion ◽  
Noble Metal ◽  
Metal Nanocrystals

The Role of Electrostatic Interactions in Protease Surface Diffusion and the Consequence for Interfacial Biocatalysis

Langmuir ◽  
2010 ◽  
Vol 26 (24) ◽  
pp. 18916-18925 ◽  
Author(s):  
Bob E. Feller ◽  
James T. Kellis ◽  
Luis G. Cascão-Pereira ◽  
Channing R. Robertson ◽  
Curtis W. Frank
Keyword(s):  
Surface Diffusion ◽  
Electrostatic Interactions

scholarly journals Trafficking to the primary cilium membrane

2017 ◽  
Vol 28 (2) ◽  
pp. 233-239 ◽  
Author(s):  
Saikat Mukhopadhyay ◽  
Hemant B. Badgandi ◽  
Sun-hee Hwang ◽  
Bandarigoda Somatilaka ◽  
Issei S. Shimada ◽  
...  
Keyword(s):  
Membrane Proteins ◽  
Signaling Pathways ◽  
Primary Cilium ◽  
Hedgehog Signaling ◽  
Diffusion Barriers ◽  
Disease Pathogenesis ◽  
Ciliary Membrane ◽  
Multiple Organs ◽  
Sensory Reception

The primary cilium has been found to be associated with a number of cellular signaling pathways, such as vertebrate hedgehog signaling, and implicated in the pathogenesis of diseases affecting multiple organs, including the neural tube, kidney, and brain. The primary cilium is the site where a subset of the cell's membrane proteins is enriched. However, pathways that target and concentrate membrane proteins in cilia are not well understood. Processes determining the level of proteins in the ciliary membrane include entry into the compartment, removal, and retention by diffusion barriers such as the transition zone. Proteins that are concentrated in the ciliary membrane are also localized to other cellular sites. Thus it is critical to determine the particular role for ciliary compartmentalization in sensory reception and signaling pathways. Here we provide a brief overview of our current understanding of compartmentalization of proteins in the ciliary membrane and the dynamics of trafficking into and out of the cilium. We also discuss major unanswered questions regarding the role that defects in ciliary compartmentalization might play in disease pathogenesis. Understanding the trafficking mechanisms that underlie the role of ciliary compartmentalization in signaling might provide unique approaches for intervention in progressive ciliopathies.

Some Comparisons of Ag Deposits on Ge and Si(111)

1992 ◽  
Vol 280 ◽  
Author(s):  
F. L. Metcalfe ◽  
J. A. Venables
Keyword(s):  
Crystal Growth ◽  
Surface Diffusion ◽  
Secondary Electron ◽  
Diffusion Length ◽  
Effective Diffusion ◽  
Rate Equations ◽  
Kinetic Rate ◽  
Annealing Conditions ◽  
Electron Imaging

ABSTRACTCrystal growth and surface diffusion have been studied in the Ag/Ge(lll) system using UHV-SEM based techniques, biassed secondary electron imaging (b-SEI), micro-AES and RHEED. Ag was deposited through and past a mask of holes held close to the substrate at 300<Td< 775K. Under certain conditions, the Ag patches were observed to split into two regions corresponding to the √3×√3R30° (hereafter √3) and a lower coverage 4×4 structure, each of which were easily observable using b-SEI. These patch widths were measured as a function of Td, and of annealing times at temperatures Ta, and effective diffusion coefficents extracted. The diffusion length of adatoms over the 4×4 structure is larger than that over the √3 structure. These observations are modelled using kinetic rate equations, and the results are compared with previous studies of Ag/Si(111). We find that energies characterising processes on top of the √3 layers of both systems are very similar, but that processes involved in the formation of the layers are quite different. The coverage of the √3 Ag/Ge(111) layer is close to 1 ML for all Td studied, unlike √3 Ag/Si(111). where it depends on deposition and annealing conditions.

The role of mood congruency memory effects in dream recall: A pilot study.

Dreaming ◽  
2009 ◽  
Vol 19 (2) ◽  
pp. 113-118 ◽  
Author(s):  
Michael Schredl ◽  
Manuela E. Hebel ◽  
Rosemarie C. Klütsch ◽  
Lena J. Liehe
Keyword(s):  
Pilot Study ◽  
Memory Effects ◽  
Dream Recall

On the Role of Surface Diffusion in Stress Relaxation During Electromigration

1995 ◽  
Vol 391 ◽  
Author(s):  
L.M. Klinger ◽  
L. Levin ◽  
E.E. Glickman
Keyword(s):  
Stress Relaxation ◽  
Surface Diffusion ◽  
Hydrostatic Stress ◽  
Stress Gradient ◽  
Film Surface ◽  
Diffusional Creep ◽  
Atomic Diffusion ◽  
Material Transport ◽  
Diffusional Flux

AbstractWe report on the role of surface diffusion involved in relaxation of electromigration (EM) induced compressive stresses in relation to hillock growth and EM behavior of interconnects. Two competing mechanisms of EM stress relaxation by material transport onto the surface are considered. The first is hillocking by threshold diffusional creep (TCH), with rather large blocks of material (grains or group of grains) involved in plastic flow. The second mechanism, atomic diffusion hillocking (ADH), is presumed to be a nonthreshold one, and represents atomic grain boundary (GB) diffusion stimulated by the hydrostatic stress gradient in the direction normal to the film surface. The latter process involves surface diffusion because GB diffusional flux onto the surface must be coupled with the flux of redistribution of the atoms over the surface. If ADH acts rapidly, this should prevent the build-up of the matter at the down-wind (anode) end of the stripe, and thus, eliminate the Blech EM threshold resulting from the stress-gradient along the stripe. The question as to whether GB diffusion capable of transporting atoms pushed by electron wind along the stripe is also effective in relieving compressive stress by GB migration of the surplus atoms in the normal direction, has remained open up to now. The problem is especially acute for short or/and narrow lines separated into short polycrystalline segments, where the Blech threshold effects are critical to EM reliability.We derived the main features of the EM behavior in drift velocity test geometry assuming that both TCH and ADH are operative. The result can be compared with available and future experimental observations in order to reveal if and when the ADH mechanism with surface diffusion involved works.

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