Pore space INDEX

Porosity (ej>) determination with NMR is a direct measurement as the response is from the fluid(s) in the pore space of the rock. The initial amplitude (before relaxation) of the NMR response of the fluid(s) saturated rock (corrected for hydrogen index) is compared with the amplitude of the response of bulk water having the same volume as the bulk volume of the rock sample. The 2 MHz NMR... 

If the NMR response is capable of estimating the pore size distribution, then it also has the potential to estimate the fraction of the pore space that is capable of being occupied by the hydrocarbon and the remaining fraction that will only be occupied by water. The Free Fluid Index (FFI) is an estimate of the amount of potential hydrocarbons in the rock when saturated to a given capillary pressure. It is expressed as a fraction of the rock bulk volume. The Bulk Volume Irreducible (BVI) is the fraction of the rock bulk volume that will be occupied by water at the same capillary pressure. The fraction of the rock pore volume that will only be occupied by water is called the irreducible water saturation (Siwr = BVI/cj>). The amount of water that is irreducible is a function of the driving force to displace water, i.e., the capillary pressure. Usually the specified driving force is an air-water capillary pressure of 0.69 MPa (100 psi). 

Pore space-clay ratio, an important index to physical character of soil. Proc. Soil Sci. Soc. America, 1 23-37. 

However, in a later work Kruk et al. [31] reported the successful use of ATRP for the controlled preparation of brushes inside quite narrow pores (-15 nm diameter) of ordered mesoporous silica with a low polydispersity index (<1.1), as long as the grafted chains do not fill the pore space completely. It is very probable that system-specific issues affect properties of the resulting concave brushes, something that has to be studied further. 

Sol-gel techniques are being employed to fabricate components not only for mainstream applications such as photonics, thermal insulation, electronics and microfluidics, but also for more exotic applications such as space dust and radiation collectors [1]. Methods have been developed to tailor the physical properties of sol-gel materials to the requirements of a specific application. For example, porosity and pore size distribution can be controlled by forming micelles in a sol [2-4-] gels can be made hydrophobic by derivatizing the otherwise hydrophilic pore walls with hydrophobic moieties [5] superhydrophilicity can be obtained by ultraviolet irradiation [6, 7] mechanical strength can be increased by cross-linking the oxide nanoparticles that make up the gel [1, 8, 9], and optical properties can be controlled by adding chromophores and nanoparticles to control index of refraction, absorption and luminescence [10-12]. 

Powder X-ray diffraction patterns of samples AIMS-1 and TiMS-6 are shown in Fig.1. The distinctive characteristic of these diffractograms is that they exhibit reflections only at small angles 29 (<60). From the comparison with published data [2] it follows that they can be indexed on a hexagonal lattice typical of MCM-41. Broadness of the (100) reflection might be attributed to a certain distribution of pore sizes in the MCM-41 materials. The XRD d-)oo spacing and the lattice constant = = 2.dioo " 3 of samples prepared are given in Tab.1 and 2. 

The pore size is determined by the distribution of spheres of different racUi in the porous structure, where the pore radius is equal to the radius of the sphere that in its inside is formed by the empty phase (Schulz et al, 2007). To avoid that large spaces are fractioned into smaller spaces, the spheres radii begin to be modified from a maximum limit to unity. The characterized spaces are identified by the following index function ... 

It is assumed that the opening space is filled with solvent, such as alcohol. This means that the capillary force is low enough to make the shrinkage of a gel film small during the drying process, and opening spaces can remain as pores in the film after heat treatment (Sakka, 1988). Presence of these pores in a film gives rise to smaller refractive index of silica film with 2.5 r < 5 than 1.45, refractive index of dense silica. 

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