Slit-pore

A7 Ethane/methane selectivity calculated from grand canonical Monte Carlo simulations of mixtures in slit IS at a temperature of 296 K. The selectivity is defined as the ratio of the mole fractions in the pore to the ratio of mole fractions in the bulk. H is the slit width defined in terms of the methane collision diameter (Tch,- (Figure awn from Crackncll R F, D Nicholson and N Quirke 1994. A Grand Canonical Monte Carlo Study ofLennard-s Mixtures in Slit Pores 2 Mixtures of Two-Centre Ethane with Methane. Molecular Simulation 13 161-175.)... 

M. Schoen, D. J. Diestler, J. H. Cushman. Fluids in micropores. I. Structure of a simple classical fluid in a slit-pore. J Chem Phys 27 5464-5476, 1987. 

P. Roeken. Capillary eondensation of simple fluids in ehemieally struetured slit-pores from statistieal-meehanieal ealeulations to a thermodynamie theory. PhD dissertation, Teehnisehe Universitat Berlin, Berlin, 1998. 

The principal effect of the presence of a smooth wall, compared to a free surface, is the occurrence of a maximum in the density near the interface due to packing effects. The height of the first maximum in the density profile and the existence of additional maxima depend on the strength of the surface-water interactions. The thermodynamic state of the liquid in a slit pore, which has usually not been controlled in the simulations, also plays a role. If the two surfaces are too close to each other, the liquid responds by producing pronounced density oscillations. 

FIG. 3 Setup of simulation cell of confined electrolyte with periodic boundary conditions, (a) Electrolyte bound by two infinitely long charged plates, representing a slit pore, (b) Electrolyte in a cylindrical nanopore. 

Travis, K. P., Gubbins, K. E., Poiseuille flow of Lennard-Jones fluids in narrow slit pores, J. Chem. Phys. 112, 4 (2000) 1984-1994. 

Both a uniform bulk fluid and an inhomogeneous fluid were simulated. The latter was in the form of a slit pore, terminated in the -direction by uniform Lennard-Jones walls. The distance between the walls for a given number of atoms was chosen so that the uniform density in the center of the cell was equal to the nominal bulk density. The effective width of the slit pore used to calculate the volume of the subsystem was taken as the region where the density was nonzero. For the bulk fluid in all directions, and for the slit pore in the lateral directions, periodic boundary conditions and the minimum image convention were used. 

Figure 7 also shows results for the thermal conductivity obtained for the slit pore, where the simulation cell was terminated by uniform Lennard-Jones walls. The results are consistent with those obtained for a bulk system using periodic boundary conditions. This indicates that the density inhomogeneity induced by the walls has little effect on the thermal conductivity. 

Q. Y. Wang and J. K. Johnson, Molecular simulation of hydrogen adsorption in single-walled carbon nanotubes and idealized carbon slit pores,./ Chem. Phys., 110, 577-586 (1999). 

Fig. 14.3 High resolution electron micrographs of the thermal transformation of goethite to hematite showing (Gt[001]//[Hm[210] orientation. Upper Gradual development (a d) of slit pores along Hm[001]. Lower Largely transformed region along the (Gt[001]//[Hm[210] orientation. Electron diffraction patterns in the in-...

Figure 3. GCMC simulated Xe adsorption isotherms on a graphite slit pore at 300 K. Experimetal isotherms are also shown. w= 0.90 nm, w= l.OOnm 0 P5, O P10, P20...

Figure 4.14 Pores may vary in size, shape, and connectivity a channel/cage structures b polygonal capillaries c ink bottle pores d laminae e slit pores.

Do DD, Nicholson D, and Do HD. Heat of adsorption and density distribution in slit pores with defective walls GCMC simulation studies and comparison with experimental data. Appl. Surf. Sci., 2007 253(13 SPEC. ISS.) 5580-5586. 

Pantatosaki E, Psomadopoulos D, Steriotis T, Stubos AK, Papaioannou A, and Papadopoulos GK. Micropore size distributions from C02 using grand canonical Monte Carlo at ambient temperatures Cylindrical versus slit pore geometries. Colloids Surf. A Physicochem. Eng. Aspects, 2004 241(1-3) 127-135. 

With the help of Equation 6.35 and Equation 6.30b for the H-K method, Equation 6.32b for the S-F method, and Equation 6.34 Cheng and Yang (Ch-Y) method, it is possible to calculate the MPSD for the slit pore geometry [17], for the cylindrical pore geometry, and for the spherical pore geometry [19], respectively. The original H-K method states that the relative pressure, x = P/P0, required for the tilling of micropores of a concrete size and shape is directly related to... 

In relation to methane adsorption in active carbon, which as previously described is formed by slit pores (see Figure 2.21), several numerical simulations have revealed that the highest density of the adsorbed phase is achieved within slit pores of 1.12-1.14 nm of diameter [187,200], For slit pores of a width, L = 1.13 nm (see Figure 2.21), two facing methane molecule monolayers may be inserted between pore walls [203-205],... 

In active carbons, micropores are slit-shaped, as represented in Figure 2.21 [201], In the image (Figure 2.21) of the slit pore are also described the meaning of the physical pore width, L and the accessible inner space, l [35,201], The parameter L is in general measured with the help of the adsorption of N2 at 77 K and Ar at 87 K [2] and the inner pore-wall spacing, l, is given by the relation [187,202]... 

The results obtained with the slit pore model are not reported since the calculated values do not agree with the experiment [97], This is an expected outcome, since the zeolite geometry can be modeled with the cylindrical pore or the spherical pore geometries, but not with the slit pore geometry. 

Monte Carlo Simulation for Distribution Equilibrium between Supercritical Fluid and Slit Pores... 

Because of its diatomic nature and permanent quadrupole moment, the physisorp-tion of nitrogen at 77 K presents special problems. The application of DFT is facilitated if the molecules are assumed to be spherical, which was the approach originally adopted by Seaton et al. (1989) and also by Lastoskie et al. (1993). The analytical procedures already outlined in Chapter 7 (Section 7.6) do not depend on the meniscus curvature and are in principle applicable to both capillary condensation and micropore filling. The non-local version of the mean field theory (NLDFT), which was used by Lastoskie, gave excellent agreement with computer simulation when applied to the carbon slit pore model. However, as pointed out earlier, these computational procedures are not entirely independent since they involve the same model parameters. 

Q1 The glomerulus is a ball of capillaries which is part of the renal corpuscle the other portion of this structure is Bowman s capsule, which forms the start of the nephron. The wall of Bowman s capsule is composed of a layer of specialized epithelial cells with extensions or foot processes which are in contact with the glomerulus and are called podocytes. The gaps between the foot processes are known as slit pores. These pores allow small molecules to pass through the epithelial layer into the nephron tubules. Below the epithelium is a basement membrane which prevents the passage of large proteins and whole cells into the renal tubules. 

We implement a modified version of the reconstruction method developed in a previous work to model two porous carbons produced by the pyrolysis of saccharose and subsequent heat treatment at two different temperatures. We use the Monte Carlo g(r) method to obtain the pair correlation functions of the two materials. We then use the resulting pair correlation functions as target functions in our reconstruction method. Our models present structural features that are missing in the slit-pore model. Structural analyses of our resulting configurations are useful to characterize the materials that we model. 

Figure 2 Comparison of isotherms generated by the two-stage HK method (solid lines) and DFT (diamonds) for nitrogen adsorption at 77 K in carbon slit pores of width (fi-om left to right) 10, 15 and 67 A.

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