Size-confinement studies

Mao et al. [478] have applied in situ STM to study Sn UPD on reconstructed and unreconstructed Au(lll) electrodes. On the unreconstructed Au(lll), Sn formed size-confined two-dimensional clusters of 1-2 nm. At more negative potential, surface alloying was observed. On the reconstructed Au(lll) surface, in turn, Sn preferably nucleated at face-centered cubic regions. The nuclei expanded toward the hexagonal close-packed regions to build up deposit domains. 

Liu, Y., Panagiotopoulos, A. Z., and Debenedetti, P. G. 2010. J. Chem. Phys. Finite-size scaling study of the vapor-liquid critical properties of confined fluids Crossover from three dimensions to two dimensions. 132 144107. 

The crystallization temperature (T ) has been found to decrease with pore size. Woo et al. [197] infiltrated linear polyethylene (PE) in AAO templates. Several pore sizes were studied, from 15 to llOnm, and even though a clear decreasing trend with pore size diameter was found, the crystallization temperatures found were too high to correspond to homogeneous nucleation of PE (see [92,97,100,112,200]). The nucleation of the confined PE nanocylinders must have been produced by surface nucleation. Similar results of decreasing with pore size have been reported for infiltrated PP [190], PEO [227,200, 202], and PE-b-PS [200] diblock copolymers. 

The effect of supply air temperature on jet behavior in confined spaces was studied by Miillejans. Studies of cooled air jets were conducted in rooms with a size from 1.0 m x 1.0 m x 1.6 m to 2.27 m x 3.33 m x 5.31 m with an air supply through the slot (b = or rectangular opening (h B. . Numerous smoke photographs were taken reflecting supply situa-... 

Lu, Vyn, Sandus and Slagg (Ref 17) conducted ignition delay time and initiation studies on solid fuel powder-air mixts in an attempt to determine the feasibility of solid-air detonations. The materials investigated included Al, Mg, Mg-Al alloy, C and PETN. Ignition delay time was used as a method of screening the candidate fuels for further work in initiation studies which determined detonation wave speed, detonation pressure, detonation limits, initiation requirements, and the effect of particle size and confinement. The testing showed the importance of large surface area per unit mass, since the most... 

A question of practical interest is the amount of electrolyte adsorbed into nanostructures and how this depends on various surface and solution parameters. The equilibrium concentration of ions inside porous structures will affect the applications, such as ion exchange resins and membranes, containment of nuclear wastes [67], and battery materials [68]. Experimental studies of electrosorption studies on a single planar electrode were reported [69]. Studies on porous structures are difficult, since most structures are ill defined with a wide distribution of pore sizes and surface charges. Only rough estimates of the average number of fixed charges and pore sizes were reported [70-73]. Molecular simulations of nonelectrolyte adsorption into nanopores were widely reported [58]. The confinement effect can lead to abnormalities of lowered critical points and compressed two-phase envelope [74]. 

As was demonstrated in the preceding sections, structure-sensitivity phenomena are mostly confined to particle size regimes smaller than 3-4 nm. A process of industrial relevance was investigated by de Jong et al. [127] in their study on cobalt particle size effects in the Fischer-Tropsch reaction. Earlier works noted distinct drop in activity for Co particles smaller than lOnm and ascribed this phenomenon to either a partial oxide or carbide formation which should be enhanced for particles in this size regime [128-139]. In order to avoid similar effects, de Jong used... 

The study of how fluids interact with porous solids is itself an important area of research [6], The introduction of wall forces and the competition between fluid-fluid and fluid-wall forces, leads to interesting surface-driven phase changes, and the departure of the physical behavior of a fluid from the normal equation of state is often profound [6-9]. Studies of gas-liquid phase equilibria in restricted geometries provide information on finite-size effects and surface forces, as well as the thermodynamic behavior of constrained fluids (i.e., shifts in phase coexistence curves). Furthermore, improved understanding of changes in phase transitions and associated critical points in confined systems allow for material science studies of pore structure variables, such as pore size, surface area/chemistry and connectivity [6, 23-25],... 

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