Diffusion field in coal stratum

1991 ◽  
Vol 27 (4) ◽  
pp. 368-370 ◽  
Author(s):  
I. L. Éttinger
Keyword(s):  
Diffusion Field ◽  
Coal Stratum

Diffusion field ahead of a growing columnar front: Discussion of the columnar-equiaxed transition

1981 ◽  
Vol 29 (2) ◽  
pp. 365-374 ◽  
Author(s):  
S. Witzke ◽  
J.-P. Riquet ◽  
F. Durand
Keyword(s):  
Diffusion Field ◽  
Columnar Front

Investigation of Ion Transport in Polypyrrole Modified Ultra-Microelectrodes During Scanning Electrochemical Microscopy

2016 ◽  
Author(s):  
Vinithra Venugopal ◽  
Vijay Venkatesh ◽  
Vishnu Baba Sundaresan
Keyword(s):  
Scanning Electrochemical Microscopy ◽  
Redox Mediator ◽  
Electrochemical Measurements ◽  
Bulk Solution ◽  
Electrochemical Technique ◽  
Diffusion Field ◽  
Faradaic Current ◽  
Constant Height ◽  
Electrolyte Bulk ◽  
Electrochemical Microscopy

Scanning electrochemical microscopy (SECM) is an electrochemical technique used to measure faradaic current changes local to the surface of a sample. The incorporation of shear force (SF) feedback in SECM enables the concurrent acquisition of topographical data of substrates along with electrochemical measurements. Contemporary SECM measurements require a redox mediator such as ferrocene methanol (FcMeOH) for electrochemical measurements; however, this could prove detrimental in the imaging of biological cells. In this article, nanoscale polypyrrole membranes doped with dodecylbenzene sulfonate (PPy(DBS)) are deposited at the tip of an ultra-microelectrode (UME) to demonstrate a novel modification of the contemporary SECM-SF imaging technique that operates in the absence of a redox mediator. The effect of distance from an insulating substrate and bulk electrolyte concentration on sensor response are examined to validate this technique as a tool for correlated topographical imaging and cation flux mapping. Varying the distance of the PPy(DBS) tipped probe from the substrate in a solution containing NaCl causes a localized change in cation concentration within the vicinity of the membrane due to hindered diffusion of ions from the bulk solution to the diffusion field. The cation transport into the membrane in close proximity to the substrate is low as compared to that in the electrolyte bulk and asymptotically approaches the bulk value at the sense length. At a constant height from the base, changing the bulk NaCl concentration from 5 mM to 10 mM increases the filling efficiency from 35% to 70%. Further, the sense length of this modified electrode in NaCl is about 440 nm which is significantly lower as compared to that of a bare electrode in ferrocene methanol (5–20 μm). It is postulated that this novel technique will be capable of producing high resolution maps of surface cation concentrations, thus having a significant impact in the field of biological imaging.

Stochastic Nature of the Casting Solidification Displayed by Micro-Modelling and Cellular Automata Method

2013 ◽  
Vol 197 ◽  
pp. 101-106
Author(s):  
Andriy A. Burbelko ◽  
Daniel Gurgul ◽  
Wojciech Kapturkiewicz ◽  
Jacek Początek ◽  
Marek Wróbel
Keyword(s):  
Diffusion Field ◽  
Thin Wall ◽  
Cooling Curves ◽  
Limited Growth ◽  
Voronoi Polyhedron ◽  
Stochastic Nature ◽  
Shape Prediction ◽  
Diffusion Limited ◽  
Average Shape ◽  
Solidification Processes

Some aspects of stochastic nature of the solidification processes are described. Firstly, the influence of the random grains nucleation on the cooling curves repeatability in the thin wall casting is presented. Secondly, the foundations of an average shape prediction for geometry of ele¬mentary diffusion field (concept of the Averaged Voronoi Polyhedron, AVP) are shown for the mi¬cro-modelling of the diffusion limited growth. Stochastic nature of the grains nucleation and growth is taken into account in the solidification modelling based on the Cellular Automaton technique (CA).

The growth kinetics of individual ledges during solid-solid phase transformations

1981 ◽  
Vol 378 (1774) ◽  
pp. 351-368 ◽  
Keyword(s):  
Phase Transformations ◽  
Volume Diffusion ◽  
Solid Phase ◽  
Parent Phase ◽  
Steady Motion ◽  
Diffusion Field ◽  
Lateral Growth ◽  
Small Perturbations ◽  
Step Motion ◽  
Kinetics Of

The problem of step motion during lateral growth in solid-solid phase transformations is re-examined. Results are obtained for the steady motion of an individual ledge when volume diffusion in the parent phase is the predominant contribution to the growth rate. A comparison is made between our results and the earlier work of Jones & Trivedi (1971). There are significant differences between the two sets of results particularly in the limit of small perturbations to the Laplacian diffusion field. To confirm the accuracy of the results presented here the calculations have been made by two different methods.

EM-ACROSS System and Corresponding Tensor Transfer Functions in Diffusion Field Region

2010 ◽  
pp. 177-191
Author(s):  
Takahiro Nakajima ◽  
Takahiro Kunitomo ◽  
Hiromichi Nagao ◽  
Mineo Kumazawa ◽  
Naotaka Shigeta
Keyword(s):  
Transfer Functions ◽  
Diffusion Field ◽  
Field Region
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