Diffuse interface

Schaaf P, Dejardin Ph and Schmitt A 1985 Reflectometrie appliquee aux interfaces diffuses possibilites et limites de la technique Rev. Phys. Appl. 20 631-40... 

Hansen CL, Skordalakes E, Berger JM, Quake SR (2002) A robust and scalable microfluidic metering method that allows protein crystal growth by free interface diffusion. Proc Natl Acad Sci USA 99 16531-16536 Herzig-Marx R, Queeney KT, Rebecca JJ, Schmidt MA, Jensen KF (2004) Infrared spectroscopy for chemically specific sensing in silicon-based microreactors. Anal Chem 76 6476-6483... 

The actual processes of uptake of chemical species by an organism typically encompass transport in the medium, adsorption at extracellular cell wall components, and internalisation by transfer through the cell membrane. Each of these steps constitutes a broad spectrum of physicochemical aspects, including chemical interactions between relevant components, electrostatic interactions, elementary chemical kinetics (in this volume, as pertains to the interface), diffusion limitations of mass transfer processes, etc. 

The liquid-liquid free interface diffusion (FID) method, in which protein and precipitant solutions are carefully superimposed and left to slowly mix diffusively, was least used in the past due to handling difficulties. However, in the last 4 years the free interface technique has experienced a revival for both screening and optimization procedures. The... 

A microfluidic chip has been developed for rapid screening of protein crystallization conditions (Hansen et al., 2002) using the free interface diffusion method. The chip is comprised of a multilayer, silicon elastomer and has 480 valves operated by pressure. The valves are formed at the intersection of two channels separated by a thin membrane. When pressure is applied to the top channel it collapses... 

Figure 6.3a shows the idealized sketch of concentration profiles near the interface by the 1 latta model, for the case of gas absorption with a very rapid second-order reaction. The gas component A, when absorbed at the interface, diffuses to the reaction zone where it reacts with B, which is derived from the bulk of liquid by diffusion. Ihe reaction is so rapid that it is completed within a very thin reaction zone this can be regarded as a plane parallel to the interface. The reaction product diffuses to the liquid main body. The absorption of CO2 into a strong aqueous KOH solution is close to such a case. Equation 6.21 provides the enhancement... 

Szymczak (1997, 1999) has stressed the possibility to distinguish between pure interface effects, i.e. surface magnetostriction, and the effects of an interface diffusion layer. Since magnetic anisotropy and magnetostriction have the same origin, the surface magnetostriction is expected to have an intrinsic character. In Szymczak s notation (Voigt... 

Figure 19.10 Schematic view of concentration profile across a wall boundary between different media with a boundary layer of thickness 8 on the B-side of the interface. Diffusivities are DB —> in the...

Heat release or consumption by surface reactions contributes to the energy balance at a gas-surface interface. Diffusive and convective fluxes in the gas phase are balanced by thermal radiative and chemical heat release at the surface. This balance is stated as... 

A fixed amount of condensed phase enclosed by an interface will undergo essentially the same process, except that the time scales may differ greatly. For solid phases, the interfaces will reduce gradients in curvature by diffusional processes such as interface diffusion, crystal diffusion, and vapor transport. At similar time scales (in the case of crystal diffusion) interfaces will move because atoms will experience differences in diffusion potential across an interface arising from differences in the curvature according to Eq. 3.76. 

Adsorbed molecules may diffuse laterally at the interface. Although surface diffusion is well-known in classical surface chemistry 33), data on adsorbed macromolecules is sparse. Burghardt and Axelrod3+) and Michaeli et al. 35) have both demonstrated rapid interface diffusion of adsorbed albumin. 

Step 2 is usually limited by the permeability of the membrane. In certain sensor designs, the membrane is eliminated to avoid this step. Step 4 refers to the diffusion of the solvated gas in the electrolyte to the electrode-electrolyte interface. Diffusion in liquids is often considerably slower than diffusion across a membrane. If the sensing electrode is flooded with electrolyte, the response is slow because the gas must diffuse through the electrolyte before reaching the reaction surface. 

It was already noted in early publications [165,184] (similar procedure is traditionally used in the QCA for describing various properties thermodynamic, phase interfaces, diffusion processes, kinetics of reactions) that for R — 1 the dimension of a system of equations can be lowered sharply if one goes over from equations in the variables 0,- and Oy, to new variables Xt with the aid of the following relation ... 

Various dynamic processes have been investigated using computer simulations of phospholipids. These include the dynamics of the alkyl chain movement of the phospholipid, the structure of water at the interface, diffusion of small molecules, interactions of phospholipids with water, dmgs, peptides, and proteins, and the effect of unsaturation or the presence of cholesterol on the phospholipid conformation. 

Saiz et al. (1998) considered that in the case of a triple line, the L/V surface can play the role of a grain boundary and the wetting ridge can move either by bulk or surface (or interface) diffusion of solid atoms (Figure 2.14). They treated the case of surface diffusion with n = 4, taking into account the difference of diffusivities at the S/V surfaces and S/L interfaces. In their experiments with Cu and Ni droplets on AI2O3 surfaces (see Section 1.2.4), Saiz et al. maintained the... 

Table 6.3 Interfacial compositions and rates of interface diffusion at the bottom of the column in Example 6.4...

Conventional free interface diffusion achieves high transient levels of supersaturation, but has a complicated spatial/temporal gradient due to the constant cross-section of the capillary. This gradient couples the kinetics and thermodynamics of traditional free interface diffusion assays in a way that pFID does not. 

Microfluidic Free Interface Diffusion 1 hour Equilibration of Bromophenol Blue... 

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