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Title: K%2B/Na%2B selectivity in K-channels and valinomycin: Phase-activated Vs phase-tolerant mechanisms.

Abstract

Abstract not provided.

Authors:
; ;
Publication Date:
Research Org.:
Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
Sponsoring Org.:
USDOE National Nuclear Security Administration (NNSA)
OSTI Identifier:
1148089
Report Number(s):
SAND2007-3997J
522881
DOE Contract Number:
DE-AC04-94AL85000
Resource Type:
Journal Article
Resource Relation:
Journal Name: Pnas; Related Information: Proposed for publication in pnas.
Country of Publication:
United States
Language:
English

Citation Formats

Varma, Sameer, Rempe, Susan, and Sabo, Dubravko. K%2B/Na%2B selectivity in K-channels and valinomycin: Phase-activated Vs phase-tolerant mechanisms.. United States: N. p., 2007. Web.
Varma, Sameer, Rempe, Susan, & Sabo, Dubravko. K%2B/Na%2B selectivity in K-channels and valinomycin: Phase-activated Vs phase-tolerant mechanisms.. United States.
Varma, Sameer, Rempe, Susan, and Sabo, Dubravko. Fri . "K%2B/Na%2B selectivity in K-channels and valinomycin: Phase-activated Vs phase-tolerant mechanisms.". United States. doi:.
@article{osti_1148089,
title = {K%2B/Na%2B selectivity in K-channels and valinomycin: Phase-activated Vs phase-tolerant mechanisms.},
author = {Varma, Sameer and Rempe, Susan and Sabo, Dubravko},
abstractNote = {Abstract not provided.},
doi = {},
journal = {Pnas},
number = ,
volume = ,
place = {United States},
year = {Fri Jun 01 00:00:00 EDT 2007},
month = {Fri Jun 01 00:00:00 EDT 2007}
}
  • Abstract not provided.
  • Abstract not provided.
  • The crystallization and phase transformation of glassy Na{sub 2}O{center_dot}2B{sub 2}O{sub 3} have been studied by X-ray diffraction, infrared spectroscopy, thermal analysis, and density measurement. By employing proper thermal treatment methods, three metastable and two relatively stable polymorphs of Na{sub 2}O{center_dot}2B{sub 2}O{sub 3} are obtained, as well as two other compounds, Na{sub 2}O{center_dot}B{sub 2}O{sub 3} and 2Na{sub 2}O{center_dot}5B{sub 2}O{sub 3}. The possible structural groups of these phases are deduced, which are found to be similar to that existing in the glass. Current glass models which imply the existence of structural ``granularity`` satisfactorily describe the crystallization behavior. The phase transformation is observedmore » to depend not only on temperature, but also on the density of the phase.« less
  • Selectivity is one of the most fundamental concepts in natural sciences, and it is also critically important in various technological, industrial, and medical applications. Although there are many experimental methods that allow to separate molecules, frequently they are expensive and not efficient. Recently, a new method of separation of chemical mixtures based on utilization of channels and nanopores has been proposed and successfully tested in several systems. However, mechanisms of selectivity in the molecular transport during the translocation are still not well understood. Here, we develop a simple theoretical approach to explain the origin of selectivity in molecular fluxes throughmore » channels. Our method utilizes discrete-state stochastic models that take into account all relevant chemical transitions and can be solved analytically. More specifically, we analyze channels with one and two binding sites employed for separating mixtures of two types of molecules. The effects of the symmetry and the strength of the molecular-pore interactions are examined. It is found that for one-site binding channels, the differences in the strength of interactions for two species drive the separation. At the same time, in more realistic two-site systems, the symmetry of interaction potential becomes also important. The most efficient separation is predicted when the specific binding site is located near the entrance to the nanopore. In addition, the selectivity is higher for large entrance rates into the channel. It is also found that the molecular transport is more selective for repulsive interactions than for attractive interactions. The physical-chemical origin of the observed phenomena is discussed.« less