Membrane permeability to ions and small molecules is believed to be a critical step in the pathology of Alzheimer's disease (AD). Interactions of oligomers formed by amyloid-β (Aβ) peptides with the plasma cell membrane are believed to play a fundamental role in the processes leading to membrane permeability. Among the family of Aβs, pyroglutamate (pE)-modified Aβ peptides constitute the most a...

Byproducts of normal mitochondrial metabolism and homeostasis include the buildup of potentially damaging levels of reactive oxygen species (ROS), Ca(2+), etc., which must be normalized. Evidence suggests that brief mitochondrial permeability transition pore (mPTP) openings play an important physiological role maintaining healthy mitochondria homeostasis. Adaptive and maladaptive responses to r...

The effect of ethanol on the cytoplasmic membrane of Oenococcus oeni cells and the role of membrane changes in the acquired tolerance to ethanol were investigated. Membrane tolerance to ethanol was defined as the resistance to ethanol-induced leakage of preloaded carboxyfluorescein (cF) from cells. To probe the fluidity of the cytoplasmic membrane, intact cells were labeled with doxyl-stearic a...

Many Gram-negative bacteria, including human pathogens such as Pseudomonas aeruginosa, do not have large-channel porins. This results in an outer membrane (OM) that is highly impermeable to small polar molecules, making the bacteria intrinsically resistant towards many antibiotics. In such microorganisms, the majority of small molecules are taken up by members of the OprD outer membrane protein...

Although water, small nonelectrolytes, and gases are freely permeable through most biological membranes, apical membranes of certain barrier epithelia exhibit extremely low permeabilities to these substances. The role of integral membrane proteins in this barrier function has been unclear. To study this problem, we have ablated the mouse gene encoding uroplakin III (UPIII), one of the major pro...

We report an atomistic physical model for the passive membrane permeability of cyclic peptides. The computational modeling was performed in advance of the experiments and did not involve the use of "training data". The model explicitly treats the conformational flexibility of the peptides by extensive conformational sampling in low (membrane) and high (water) dielectric environments. The passiv...

one of the main factors of premature deterioration of concrete structures is the corrosion of reinforcements. chloride penetration of concrete is one of the main reasons of this phenomenon. therefore, to have durable structure, it is necessary to have concretes with low permeability.there are various methods to evaluate permeability of concrete. finding a relationship between them can be useful...

the performances of two-phase polymer-liquid pebax®/polyethylene glycol (peg) and three-phase polymer-liquid-solid pebax®/peg/mwnt thin film composite membranes for co2 and ch4 permeation were studied. the effect of temperature and mwnt/pebax® ratio on single gas (co2 and ch4) permeability was investigated. the permeation of both gases was measured at different temperatures from 303 to 323 ˚k. ...

The soil is a heterogeneous and anisotropic medium. Hydraulic conductivity, an intrinsic property of natural alluvial deposits varies both deterministically and randomly in space and has different values in various directions. In the present study, the permeability of natural deposits and its influence on the seepage flow through a natural alluvial deposit is studied. The 2D Finite Difference c...

Stress waves contain useful information about the properties of porous materials; they can be recovered through different non-destructive testing methods such as crosswell, vertical seismic profile, borehole logging as well as sonic tests. In all these methods, it is crucial to assess the effects of frequency on wave attributes including velocity and intrinsic attenuation. The dependency of per...