Resist development transport model

McKay, G. Al-Duri, B., and McKee, S., Development of solutions to two-resistance mass transport models based on external and pore diffusion Theoretical development and experimental results, Dev. Chem. Eng. Mineral Process., 1(2), 129-157(1993). 

A detailed transport model for resist dissolution has been developed (169). In conjunction with standard ellipsometric equations describing multilayer films, the model provides quantitative agreement with the observed traces from the in situ ellipsometer. Model parameters are thus extracted, and their significance in terms of molecular structures of the system can be established. This model can then be extended for predictive purposes in the design and selection of resist materials. 

For relatively porous nanofiltration membranes, simple pore flow models based on convective flow will be adapted to incorporate the influence of the parameters mentioned above. The Hagen-Poiseuille model and the Jonsson and Boesen model, which are commonly used for aqueous systems permeating through porous media, such as microfiltration and ultrafiltration membranes, take no interaction parameters into account, and the viscosity as the only solvent parameter. It is expected that these equations will be insufficient to describe the performance of solvent resistant nanofiltration membranes. Machado et al. [62] developed a resistance-in-series model based on convective transport of the solvent for the permeation of pure solvents and solvent mixtures ... 

Drug absorption generally occurs either through passive transcellular or paracellu-lar diffusion, active carrier transport, or active efflux mechanisms. Several methods have been developed to aid in the understanding of the absorption of new lead compotmds. The most common ones use an immortalized cell line (e.g., Caco-2, Madin-Darby canine kidney, and the like) to mimic the intestinal epithelium. These in vitro models provide more predictive permeability information than the artificial membrane systems (i.e., PAMPA and permeability assays, described previously) based on the cells ability to promote (active transport) or resist (efflux) transport. Various in vitro methods are listed in the U.S. FDA guidelines. These are acceptable to evaluate the permeability of a drug substance, and includes a monolayer of suitable epithelial cells, and one such epithelial cell line that has been widely used as a model system of intestinal permeability is the Caco-2 cell line. 

For many catalytic processes involving hydrocarbons the major deactivation pathway comes from the formation and deposition of carbonaceous species. Often referred to as coke, on many catalytic materials its deposition leads to transport resistances for reactants and products and blocks access to active sites. U nderstanding its rate of formation and impact on catalyst deactivation is of great importance in developing and modeling new catalytic processes. Developing a fundamental understanding of coke deposition enables the proper selection of catalytic materials and process conditions to minimize the impact of deactivation on a process. 

The anisotropic continuum approach to losses in multifilament conductors was first conceived by Carr, who developed the model assuming that the inductor is a continuum material with anisotropic resistivity. He applied this approach to the special case of losses in cylindrical conductors for applied transverse sinusoidal fields in the absence of transport current [ ]. Those losses resulting from pJ in the conductor are classified as eddy current or saturation hysteresis losses, depending upon the level of /. Eddy current losses result from J below Jc, with the implicit assumption of rapidly rising resistivity in the flux-flow regime with currents saturated at Jc. The magnetization loss for the continuum is essentially the magnetic hysteresis loss for the filaments times the fraction of the composite occupied by the filaments. 

Finally, Machado et al. [21] developed a resistances-in-series model and proposed that solvent transport through the MPF membrane consists of three main steps (1) transfer of the solvent into the top active layer, which is characterized by surface resistance (2) viscous flow through NF pores and (3) viscous flow through support layer pores, all expressed by viscous resistances, i.e. 

In this case, the PEM operates like a linear ohmic resistance, with irreversible voltage losses t]pem = jolpEM/ p, where jo is the fuel cell current density. In reality, this behavior is only observed in the limit of small Jo- At normal current densities of fuel cell operation, y o l A cm , the electro-osmotic coupling between proton and water fluxes causes nonuniform water distributions, which lead to nonlinear effects in tipem. These deviations result in a critical current density Jpc, at which the increase in tipem incurs a dramatic decrease of the cell voltage. It is, thus, crucial to develop membrane models that could predict the value of Jpc on the basis of primary experimental data on structure and transport properties. 

In VMD, the boundary layer resistance in the permeate side and the contribution of the heat transported by conduction through the membrane are negligible (Lawson and Lloyd, 1996a Bandini et al., 1997 Lawson and Lloyd, 1997). This makes VMD of pure water useful to determine the temperature of the feed solution at the membrane surface (T ), and therefore the boundary layer heat transfer coefficients in the membrane module can be evaluated (Mengual et al., 2004). This helps in selecting the adequate empirical heat transfer correlation of a given MD system, which is a complex task when developing theoretical models to determine the temperature polarization coefficients. 

In order to see how the electrode thickness might be optimized in order to provide the lowest electrode resistivity, we have developed a theoretical model to describe the charge/discharge processes in porous carbon electrodes. As a first approximation, let us consider an electrode having two sets of cylindrical pores, namely, nanopores (NP) of less than 3 nm in diameter and transport channels (TC) of more than 20 nm in diameter, with each nanopore having an exit to only one TC. ... 

DISCUSSION AND CONCLUSIONS In this study a general applicable model has been developed which can predict mass and heat transfer fluxes through a vapour/gas-liquid interface in case a chemical reaction occurs in the liquid phase. In this model the Maxwell-Stefan theory has been used to describe the transport of mass and heat. A film model has been adopted which postulates the existence of a well-mixed bulk and stagnant zones where the principal mass and heat transfer resistances are situated. Due to the mathematical complexity the equations have been solved numerically by a finite-difference technique. In this paper (Part I) the Maxwell-Stefan theory has been compared with the classical theory due to Pick for isothermal absorption of a pure gas A in a solvent containing component B. Component A is allowed to react by a unimolecular chemical reaction or by a bimolecular chemical reaction with... 

Figure 10. Kleitz s reaction pathway model for solid-state gas-diffusion electrodes. Traditionally, losses in reversible work at an electrochemical interface can be described as a series of contiguous drops in electrical state along a current pathway, for example. A—E—B. However, if charge transfer at point E is limited by the availability of a neutral electroactive intermediate (in this case ad (b) sorbed oxygen at the interface), a thermodynamic (Nernstian) step in electrical state [d/j) develops, related to the displacement in concentration of that intermediate from equilibrium. In this way it is possible for irreversibilities along a current-independent pathway (in this case formation and transport of electroactive oxygen) to manifest themselves as electrical resistance. This type of chemical valve , as Kleitz calls it, may also involve a significant reservoir of intermediates that appears as a capacitance in transient measurements such as impedance. Portions of this image are adapted from ref 46. (Adapted with permission from ref 46. Copyright 1993 Rise National Laboratory, Denmark.)...

The weight of soil carried in the surface runoff has been estimated by relating the sediment load to the rate of energy dissipation at the land surface by the rainfall and flowing water. The resistance of the soil to eroding forces has also been considered (4), and a method has been developed to estimate the net effect of erosion on radioaerosol transport. The volume of the liquid phase is estimated on a continuous basis by the Stanford watershed model, through consideration of a water budget. This feature has been retained in the HTM-1. 

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