The separation of small molecule gases by membrane technologies can help performance enhancement and process intensification for emerging advanced fossil energy systems with CO2 capture capacity. This paper reports the demonstration of controlled modification of zeolitic channel size for the MFI-type zeolite membranes to enhance the separation of small molecule gases such as O2 and N2. Pure-sil...

many properties of chemicals depend on their stereochemistry. among these, the effects of stereoisomerism on percutaneous absorption of drugs are not well studied. we have previously shown that permeation of tretinoin and isotretinoin (two geometric isomers) through hydrophilic enhancers-treated rat skin is stereoselective. as, depending on their lipophilicity, penetration enhancers can change ...

In this study, the charge selectivity of staphylococcal alpha-hemolysin (alphaHL), a bacterial pore-forming toxin, is manipulated by using cyclodextrins as noncovalent molecular adapters. Anion-selective versions of alphaHL, including the wild-type pore and various mutants, become more anion selective when beta-cyclodextrin (betaCD) is lodged within the channel lumen. By contrast, the negativel...

in this work we sought to determine whether vesicles (liposomes/niosomes) were able to enhance finasteride concentration in the dermis layer, including the pilosebaceous units (psu). such enhancement could be beneficial in the treatment of some androgen-related skin disorders. hamster flank skin was used to study  3hfinasteride permeation via vesicles and a hydroalcoholic solution (ha). the dru...

Although permeation of hydrocarbons such as Benzene, Toluene, Ethybenzene, and Xylene (BTEX) through polyethylene (PE) pipe in potable water applications is rarely occurred. It is important to understand permeation mechanism and characterize the potential health risk. The most common potential hydrocarbon substances are originated from gasoline leaks. Previous research has shown that pipe mater...

Biological ion channels rely on a multi-ion transport mechanism for fast yet selective permeation of ions. The crystal structure of the KcsA potassium channel provided the first microscopic picture of this process. A similar mechanism is assumed to operate in all potassium channels, but the validity of this assumption has not been well investigated. Here, we examine the energetics of ion permea...

Graphene is an ideal membrane for selective separation because of its unique properties and single-layer structure. Considerable efforts have been made to alter the permeability of graphene. In this study, we investigate the pathways for an oxygen atom to pass through graphene sheets. We also identify the effect of the ripple's curvature in graphene sheets on the energy barrier of permeation th...

this paper discusses different important gas permeation models such as “maxwell”, “bruggeman”, “lewis-neilson”, and “pal” models to predict “mixed matrix membranes” (mmms) performance. the main parameter considered and discussed is the permeability of hydrogen on carbon nanotubes (cnts)-mmm. for evaluation of the theoretical models, experimental data of permeability for h2 were compared to the ...

Aquaporins (AQPs) are a family of integral membrane proteins, which facilitate the rapid and yet highly selective flux of water and other small solutes across biological membranes. Molecular dynamics (MD) simulations contributed substantially to the understanding of the molecular mechanisms that underlie this remarkable efficiency and selectivity of aquaporin channels. This chapter reviews the ...

The representative measurement of gas concentration and fluxes in heterogeneous soils is one of the current challenges when analyzing the interactions of biogeochemical processes in soils and global change. Furthermore, recent research projects on CO(2)-sequestration have an urgent need of CO(2)-monitoring networks. Therefore, a measurement method based on selective permeation of gases through ...