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Numerical Modeling of Pit Growth in Microstructure

S. Qidwai[1], N. Kota[2], V. DeGiorgi[1]
[1]Naval Research Laboratory, Washington, DC, USA
[2]Science Applications International Corporation, Washington, DC, USA

Pitting corrosion is a complex phenomenon where rates of: i) chemical reactions, ii) diffusion of various species involve in those reactions, and iii) species dissolution at the metal-electrolyte interface are fully dependent on each other, except under special conditions or assumptions. One set of such conditions is that: a) there are no species concentration gradients due to the rapid mixing ...

Finite Element Analysis of Induced Electroosmotic Flow in Brain Tissue and Application to ex vivo Determination of Enzyme Activity

Y. Ou[1], A. Rupert[1], M. Sandberg[2], S. Weber[1]
[1]University of Pittsburgh, Pittsburgh, PA, USA
[2]University of Gothenburg, Gothenburg, Sweden

Ectopeptidases are commonly accepted to be a means of clearing active peptides. However, studies have shown that they can also regulate peptide activity. We have developed a technique of electrokinetic push-pull perfusion (Ek-PPP, Figure 1) to examine this largely unexplored mechanism of modulation of peptide function. We push the neuropeptide galanin through organotypic hippocampal slice ...

Reactive Transport Processes in Compacted Bentonite

A.E. Idiart[1], M. Pekala[1], A. Nardi[1], D. Arcos[1]
[1]Amphos 21, Barcelona, Spain

The Swedish Organization for Radioactive Waste (SKB) is considering disposal High Level Wastes in a deep underground repository. Bentonite clay is planned to be used in the near-field of the waste packages as buffer material. The buffer is expected to provide a favorable environment with limited radionuclide migration due to slow diffusion and retardation by sorption and cation-exchange effects. ...

Localization of Chemical Sources Using Stochastic Differential Equations in Realistic Environments

A. Mohammed, and A. Jeremic
McMaster University, Hamilton, L8S4K1, Canada

Signal processing algorithms for chemical sensing/monitoring have been subject of considerable research interest in the recent years mainly due to their diverse applicability. When the concentration of chemical agent is small, the dispersion of particles is governed by stochastic differential equations describing more complex motion mechanisms such as Brownian motion. In this paper we propose ...

An Approach to Modeling Vacuum Desorption - new

C. F. Gomez[1], R. Schunk[1], R. F. Coker[1], J. Knox[1]
[1]NASA Marshall Space Flight Center, Huntsville, AL, USA

The objective of this simulation effort is to develop a mathematical model of vacuum desorption on a POC (Proof of Concept) canister loaded with Zeolite 13X/5A . This canister contains a pelletized adsorption bed which is used to adsorb H2O and CO2. Once this bed is fully saturated with an equilibrium loading, desorption is then accomplished by reducing the pressure to near vacuum. This type of ...

A Wall-Cooled Fixed-Bed Reactor Model for Gas-Phase Fischer-Tropsch Synthesis - new

A. Nanduri [1], P. L. Mills [1],
[1] Department of Chemical and Natural Gas Engineering, Texas A&M University - Kingsville, Kingsville, TX, USA

In the early 1920’s, Gas-To-Liquids (GTL) and Coal-To-Liquids (CTL) technologies were developed to account for the depleting crude oil resources [1]. During this period, Franz Fischer and Hans Tropsch developed a process to convert synthesis gas (syn gas), derived from coal gasification, to a wide range of high value-added products. This process later came to be known as Fischer-Tropsch (F-T) ...

Coupled Hydrochemical Modeling for the Optimal Design of an In-situ Redox Experiment

P. Trinchero[1], J. Molinero[1], G. Román-Ross[1], A. Nardi[1], L.M. De Vries[1], T. Karvonen[2], P. Pitkänen[3]
[1]Amphos 21, Barcelona, Spain
[2]WaterHope, Helsinki, Finland
[3]Posiva, Eurajoki, Finland

In this work, we present a number of scoping calculations that have been carried out to design an in-situ redox experiment (Figure 1) focused on assessing potential changes in the pH and redox conditions and in the buffering capacity of the Olkiluoto bedrock (i.e. the site for the Finnish spent fuel repository). A characteristic of these models lies in the need to integrate prior information, ...

Modeling Fluid-Induced Porous Scaffold Deformation

J. Podichetty Thribhuvan[1], S.V. Madihally[1]
[1]Oklahoma State University, Stillwater, OK, USA

Utilization of bioreactors to regenerate tissues outside the body has been intensely investigated in functional tissue engineering. Various studies have been performed using computational fluid dynamics (CFD) to understand fluid flow within bioreactors while assuming porous scaffold as a rigid structure. However, the physical and mechanical properties of most tissue engineering scaffolds suggest ...

Chemical Reactions in a Microfluidic T-Sensor: Numerical Comparison of 2D and 3D Models

R. Winz[1][2], N. Schröder[1], W. Wiechert[1], and E. von Lieres[1]
[1]Institute of Biotechnology 2, Research Centre Jülich, Jülich, Germany
[2]Research Center for Micro and Nanochemistry, University of Siegen, Siegen, Germany

In recent years lab-on-microchip technology has become a powerful tool for micro-scale analysis of biochemical processes. In the studied system the overall process consists of transport, convection, diffusion, reaction and adsorption processes. Two compounds A and B, contained in a carrier fluid (buffer), are introduced into a reaction channel via a Y-shaped double-inlet. As the streams flow ...

Can Oscillatory Convection Accelerate Signal Propagation in Simple Epithelium?

M. Nebyla[1], M. Pribyl[1]
[1]Institute of Chemical Technology, Prague, Department of Chemical Engineering, Prague, Czech Republic

We introduce a mathematical model of signal transmission in simple epithelial layers. The mathematical model consists of reaction-transport equations for extracellular ligands, cellular receptors, ligand-receptor complexes and a ligand releasing protease. We consider diffusion and nonstationary convective transport of protein ligands in the extracellular space. The study was carried out using ...