Open pores

The dissolution of carbonates can create spectacular features like those found in many caves. The process is termed karstification. Some reservoirs are related to Karst. Examples are the Bohai Bay Field in China or the Nang Nuan oil field in the Gulf of Thailand. These reservoirs are characterised by high initial production from the large open pore system. However, since the Karst features are connected downdip to the waterleg this is usually followed by rapid and substantial water breakthrough. ... 

Open pore Cavity or channel communicating with the surface of the solid. 

Porosity Ratio of the volume of open pores to the total volume of the... 

The pore-size distribution and the nature of the pores in catalyst supports and hence the catalysts derived from them are important properties that significantly affect catalyst performance (16). In most cases, catalyst designers prefer an open-pore stmcture, that is, pores that have more than one opening, and a pore size as uniform as possible in order to obtain maximum utilization of the available pore volume. This can be achieved by careful choice of raw materials and processing conditions. 

Directed Oxidation of a Molten Metal. Directed oxidation of a molten metal or the Lanxide process (45,68,91) involves the reaction of a molten metal with a gaseous oxidant, eg, A1 with O2 in air, to form a porous three-dimensional oxide that grows outward from the metal/ceramic surface. The process proceeds via capillary action as the molten metal wicks into open pore channels in the oxide scale growth. Reinforced ceramic matrix composites can be formed by positioning inert filler materials, eg, fibers, whiskers, and/or particulates, in the path of the oxide scale growth. The resultant composite is comprised of both interconnected metal and ceramic. Typically 5—30 vol % metal remains after processing. The composite product maintains many of the desirable properties of a ceramic however, the presence of the metal serves to increase the fracture toughness of the composite. 

The single-point BET surface area measurement was used to check for open pores. The results for some soft and hard carbon samples heated at 700°C and 1000°C are presented in Table 2 for comparison. The hard carbon samples studied here have about ten times more open porosity than the soft carbons. 

The family of agarose-based gels, Sepharose, Sepharose CL, and Sepharose Fast Flow, are bead-formed gels prepared from 2, 4, or 6% agarose solutions. The matrix porosity decreases and rigidity of the bead structure increases with increasing agarose concentrations. The open pore structure and broad... 

The unhindered ionic charge transfer requires many open pores of the smallest possible diameter to prevent electronic bridging by deposition of metallic particles floating in the electrolyte. Thus the large number of microscopic pores form immense internal surfaces, which inevitably are increasingly subject to chemical attack. 

Carbons may have closed and open pores with a large variety of dimensions from a few Angstroms to several microns. In terms of structure, the pores in active carbons are divided into three basic classes [66, 69] macropores, transitional pores, and micropores. Pores are formed during the production of carbon (pyrolysis of its precursors), or can be formed by other means such as oxidation by 02, air, C02, or H20 [66]. According to Dubinin s... 

A similar, but highly porous, vitreous carbon material—reticulated vitreous carbon (RVC)—has found widespread application for flow analysis and spectro-electrochemistry (25). As shown in Figure 4-10, RVC is an open-pore ( spongelike ) material such a network combines the electrochemical properties of glassy carbon with many structural and hydrodynamic advantages. These include a very high surface area ( 66 cm2 cm-3 for the 100-ppi grade), 90-97% void volume, and a low resistance to fluid flow. 

FIGURE 4-10 The open-pore structure of reticulated vitreous carbon. 

The confinement effects of the narrow pore on the ILs and the ionic interactions between [BMIM] favor the open pore while the anion, [PF6], was attached to the open metal sites, was observed in a simulation study. It was ascertained that C02 was favorably attached to the [PF6] anions sites. The study demonstrated that IL/MOF composites are a potential candidate for C02 adsorption and have displayed significantly high CO2/N2 selectivity. To the best of our... 

Other ionophore antibiotics such as gramicidin and valinomycin are channel-forming ionophores because they open pores that extend through the membrane. 

Cancrinites are one of the rarest members of the feldspathoid group, classified as such due to its low silicon content. However, cancrinite is also classified as a zeolite, due to its open pore structure, which confers molecular sieve properties [1], Likewise, variable sodium carbonate and NaOH concentrations in the hydrothermal synthesis of cancrinite could direct the synthesis of the intermediate phase or the disordered cancrinite formation [2], The intermediate phase is described as a phase between cancrinite and sodalite [3], The disordered cancrinite is an intermediate phase which is much closer to the cancrinite structure than sodalite structure [2],... 

Pores are classified into two types open pores, which connect to the outside of the material, and the closed pores, which are totally within the material. Penetrating pores are kind of open pores these have at least two openings located on two sides of a porous material. Penetrating pores are permeable for fluid, and therefore are important in applications such as filters. Many porous materials have been used in many applications. They are classified by many different criteria such as pore size, pore shape, materials and production methods. Classification by pore size and by pore shape is useful while considering the applications of porous materials. The classification of porous materials by pore size (according to Schaefer30) differentiates between microporous pores (pore diameter < 2 nm), mesoporous pores (2 nm < pore diameter <50 nm) and macroporous pores (pore diameter > 50 nm). 

LINPOR [Linde porous medium] A biological waste water treatment process, using an open-pore plastic foam for retaining the biomass. Its use enables the capacity of an activated sludge plant to be increased without adding extra tanks. Invented at the Technische Universitat, Munich, and further developed by Linde, Munich. See also CAPTOR. 

Conducting reactions in nanospace where the dimensions of the reaction vessel are comparable to those of the reactants provides a new tool that can be used to control the selectivity of chemical transformations.1 This dimensional aspect of nano-vessels has been referred to as shape selectivity.2 The effect of spatial confinement can potentially be exerted at all points on the reaction surface but its influence on three stationary points along the reaction coordinate (reactants, transition states, and products) deserve special attention.3,4 (1) Molecular sieving of the reactants, excluding substrates of the incorrect dimension from the reaction site can occur (reactant selectivity). (2) Enzyme-like size selection or shape stabilization of transition states can dramatically influence reaction pathways (transition state selectivity). (3) Finally, products can be selectively retained that are too large to be removed via the nano-vessel openings/pores (product selectivity). 

Several approaches towards monolithic GC columns based on open pore foams prepared in large diameter glass tubes were reported in the early 1970s [26,27, 110]. However, these columns had poor efficiencies, and the foams possessed only limited sample capacities in the gas-solid GC mode. Subsequent experiments with polymerized polymer layer open tubular (PLOT) columns where the capillary had completely been filled with the polymer were assumed to be failures since the resulting stationary phase did not allow the gaseous mobile phase to flow [111]. 

The flow of water through waists surrounding an open pore is governed by the size of the waist as follows ... 

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