Analysis of high-speed (150 frames/sec) cinematographs of the filling and expulsion of the water expulsion vesicle of Tetrahymena pyriformis shows that the vesicle fills as water is pumped into it by contractions of at least four ampullary sacs which are continuous with the endoplasmic reticulum. When filled, the vesicle is pressed against its two excretory pores by cyclotic movements of the cy...

One of soil microbiology's most intriguing puzzles is how so many different bacterial species can coexist in small volumes of soil when competition theory predicts that less competitive species should decline and eventually disappear. We provide evidence supporting the theory that low pore connectivity caused by low water potential (and therefore low water content) increases the diversity of a ...

pore pressure is an important parameter, in exploration and production of hydrocarbon resources. lack of accurate knowledge about pore pressure, before drilling phase, leads to serious dangers in drilling process. accurate knowledge about distribution of pore pressure in a field, leads to reduce risks in drilling, improve well planning and mud weight calculations. during burial, normally pressu...

A two-step acid/base-catalyzed silica gel has been aged in alcohol and water baths followed by various aprotic solvents with a wide range of surface tensions. Low temperature (CO 2) and high temperature (ethanol) aerogels were also prepared. The physical and chemical structures of gels dried from aprotic solvents were studied by a series of techniques (29Si MAS-NMR, nitrogen adsorption, SAXS, e...

the characterizations of natural diatomite from birjand deposit (iran) were studied such as chemical compositions, specific surface area, total pore volume, pore size distribution and xrd. the diatomite that was treated only with sulfuric acid displayed a larger surface area, expanded total pore volume and increased pore size in comparison with both washed natural diatomite with deionized water...

Mercury cycling in the water column and upper sediments of a contaminated area, the Largo do Laranjo, Aveiro (Portugal), was evaluated after determination of reactive and non-reactive mercury concentrations in the water column and pore waters of sediments, collected in several places of this bay. In the water column, reactive mercury concentrations varied between 10 and 37 pmol dm(-3), the high...

Enterococci are used to evaluate the safety of beach waters and studies have identified beach sands as a source of these bacteria. In order to study and quantify the release of microbes from beach sediments, flow column systems were built to evaluate flow of pore water out of beach sediments. Results show a peak in enterococci (average of 10% of the total microbes in core) released from the san...

We present the results of molecular dynamics simulations on water confined in a silica pore of 15 Å modelled to mimic the MCM-41 structure. We focus on the dynamical properties of water for different hydration levels of the pore. Density profiles show a well-defined double-layer structure close to the surface. From the analysis of the layers we find that water molecules close to the substrate s...

We present results of molecular dynamics simulations of water confined in a silica pore. A cylindrical cavity is created inside a vitreous silica cell with geometry and size similar to the pores of real Vycor glass. The simulations are performed at different hydration levels. At all hydration levels water adsorbs strongly on the Vycor surface; a double layer structure is evident at higher hydra...

Deep inelastic neutron scattering measurements of water confined in nanoporous xerogel powders, with average pore diameters of 24 and 82 A, have been carried out for pore fillings ranging from 76% to nearly full coverage. DINS measurements provide direct information on the momentum distribution n(p) of protons, probing the local structure of the molecular system. The observed scattering is inte...