381,818 research outputs found
Modeling two-state cooperativity in protein folding
A protein model with the pairwise interaction energies varying as local
environment changes, i.e., including some kinds of collective effect between
the contacts, is proposed. Lattice Monte Carlo simulations on the
thermodynamical characteristics and free energy profile show a well-defined
two-state behavior and cooperativity of folding for such a model. As a
comparison, related simulations for the usual G\={o} model, where the
interaction energies are independent of the local conformations, are also made.
Our results indicate that the evolution of interactions during the folding
process plays an important role in the two-state cooperativity in protein
folding.Comment: 5 figure
Crystal nuclei templated nanostructured membranes prepared by solvent crystallization and polymer migration
Currently, production of porous polymeric membranes for filtration is predominated by the phase-separation process. However, this method has reached its technological limit, and there have been no significant breakthrough over the last decade. Here we show, using polyvinylidene fluoride as a sample polymer, a new concept of membrane manufacturing by combining oriented green solvent crystallization and polymer migration is able to obtain high performance membranes with pure water permeation flux substantially higher than those with similar pore size prepared by conventional phase-separation processes. The new manufacturing procedure is governed by fewer operating parameters and is, thus, easier to control with reproducible results. Apart from the high water permeation flux, the prepared membranes also show excellent stable flux after fouling and superior mechanical properties of high pressure load and better abrasion resistance. These findings demonstrate the promise of a new concept for green manufacturing nanostructured polymeric membranes with high performances
Minijet-associated Dilepton Production in Ultrarelativistic Heavy Ion Collisions
Dilepton production associated with minijets is calculated in
ultrarelativistic heavy ion collisions using the first order approximation of
the dilepton fragmentation functions of quarks and gluons. The full QCD
evolution of the fragmentation functions is also studied. We find that the
dilepton pairs from the fragmentation of minijets are comparable to direct
Drell-Yan at AGeV for small dilepton invariant mass 1-2
GeV/c while dominant over a large range of mass at AGeV.Comment: 23 pages in RevTex, 5 figures in uuencoded files, LBL-3440
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