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During recent years, major progress has been made in the understanding of the adsorption, pore condensation and hysteresis behavior of fluids in novel ordered nanoporous materials with well defined pore structure. This has led to major advances in the structural characterization by physical adsorption, also because of the development and availability of advanced theoretical procedures based on statistical mechanics e.g., density functional theory, molecular simulation which allows to describe adsorption and phase behavior of fluids in pores on a molecular level. Very recent improvements allow even to take into account surface geometrical inhomogeneity of the pore walls However, there are still many open questions concerning the structural characterization of more complex porous systems. Important aspects of the major underlying mechanisms associated with the adsorption, pore condensation and hysteresis behavior of fluids in micromesoporous materials are reviewed and their significance for advanced physical adsorption characterization is discussed.

Abstract We present a molecular thermodynamic approach to model mercury porosimetry. A lattice model is used to describe the intrusion/extrusion of mercury into different pore structures. The non-wetting nature of mercury is modeled by setting the wall-fluid interaction of the lattice model to repulsive values. We perform Mean-Field Density Functional Theory calculations on a mesoporous Vycor glass for different temperatures. The shape of the intrusion/extrusion curves is in good agreement with experimental observations. Visualizations of the liquid distribution in the Vycor glass reveal a fragmentation of mercury along the extrusion curve. The calculations performed on ink-bottle pore show that this fragmentation is caused by the snap-off of mercury from the necks leading to a droplet of mercury entrapped into the bottle part of the pore. This phenomenon is likely to play a role in the mechanism of mercury entrapment frequently observed during experiments.

We consider mercury porosimetry from the perspective of the statistical thermodynamics of penetration of a nonwetting liquid into a porous material under an external pressure. We apply density functional theory to a lattice gas model of the system and use this to compute intrusion/extrusion curves. We focus on the specific example of a Vycor glass and show that essential features of mercury porosimetry experiments can be modeled in this way. The lattice model exhibits a symmetry that provides a direct relationship between intrusion/extrusion curves for a nonwetting fluid and adsorption/desorption isotherms for a wetting fluid. This relationship clarifies the status of methods that are used for transforming mercury intrusion/extrusion curves into gas adsorption/desorption isotherms. We also use Monte Carlo simulations to investigate the nature of the intrusion and extrusion processes.

We present results of a systematic study on the sorption- and phase behavior of nitrogen, argon, and krypton at 77 and 87 K in different pristine mesoporous MCM-48 silica phases (BJH pore diameters 2−3 nm) and MCM-48 silica/iron(III) host compound, which consists of two interwoven, but unconnected three-dimensional pore systems. Different methods (e.g., BET, BJH, SF) were used to analyze nitrogen (77 K) and argon (87 K) sorption isotherms in order to characterize the MCM-48 silica materials with respect to surface area, pore volume and pore diameter. In contrast to nitrogen, argon, and krypton sorption isotherms on all MCM-48 silica materials reveal phase transitions accompanied by sorption hysteresis of type H1 (IUPAC classification) down to temperatures T well below the bulk triple-point temperature TR, i.e., 87 K (TR − T ≈ 28.5 K) in the case of krypton and 77 K (TR − T ≈ 6.5 K) in the case of argon. Details of the sorption hysteresis depend on temperature and pore size, e.g., with increasing temperature and decreasing pore size a shrinkage of the hysteresis loops is observed. In contrast to the argon/MCM-48 silica system, argon sorption isotherms at TR − T ≈ 6.5 K in controlled-pore glass of BJH pore diameter ca. 16 nm reveal no pore condensation and hysteresis, indicating that in such wide pores the pore condensation line does not extend down to this temperature for pressures up to the corresponding bulk sublimation pressure.

Hatchery brown trout Salmo trutta intended for stocking into Lake Michigan were exposed for 57 days to three temperature regimes: (1) a diel temperature cycle (9–18 C; mean 12.5 C; amplitude 4.6 C) simulating that selected by brown trout residing in thermal effluent areas in spring; (2) a constant 13 C, the optimum constant temperature for brown trout growth; and (3) naturally fluctuating, arrhythmic temperatures of inshore Lake Michigan waters (4–11 C; mean 7.7 C). Fish in each treatment were fed to satiation twice a day with alewife Alosa pseudoharengus. Food consumption and growth rates were nearly identical in the constant 13 C and the ambient-temperature regimes; they were significantly greater in the thermocyclic regime than in the other two regimes. Gross conversion efficiencies were not significantly different among treatments, indicating little, if any, energetic penalty for exposure to large or small diel temperature fluctuations. Brown trout exposed to a constant 13 C accumulated less total lipid (whole body) and deposited a lower proportion of lipids in muscle than fish in the fluctuating temperature regimes. Apparent acclimation temperatures of brown trout in the cyclic and the ambient regimes, based on expected food consumption and growth at constant temperatures, were at or above the maximum temperature of each exposure range.

Two conventional fishery stock assessment models, the surplus-production model and the dynamic-pool model, were applied to assess the impacts of water withdrawals by electricity-generating plants, industries, and municipalities on the standing stocks and yields of alewife Alosa pseudoharengus, rainbow smelt Osmerus mordax, and yellow perch Perca flavescens in Lake Michigan. Impingement and entrainment estimates were based on data collected at 15 power plants. The surplus-production model was fitted to the three populations with catch and effort data from the commercial fisheries. Dynamic-pool model parameters were estimated from published data. The numbers entrained and impinged are large, but the proportions of the standing stocks impinged and the proportions of the eggs and larvae entrained are small. The reductions in biomass of the stocks and in maximum sustainable yields are larger than the proportions impinged. The reductions in biomass, based on 1975 data and an assumed full water withdrawal, are 2.86% for alewife, 0.76% for rainbow smelt, and 0.28% for yellow perch. Fishery models are an economical means of impact assessment in situations where catch and effort data are available for estimation of model parameters.