Lehigh University

About: Lehigh University is a education organization based out in Bethlehem, Pennsylvania, United States. It is known for research contribution in the topics: Catalysis & Fracture mechanics. The organization has 12684 authors who have published 26550 publications receiving 770061 citations.

Balanced Protein–Water Interactions Improve Properties of Disordered Proteins and Non-Specific Protein Association

Abstract: Some frequently encountered deficiencies in all-atom molecular simulations, such as nonspecific protein–protein interactions being too strong, and unfolded or disordered states being too collapsed, suggest that proteins are insufficiently well solvated in simulations using current state-of-the-art force fields. To address these issues, we make the simplest possible change, by modifying the short-range protein–water pair interactions, and leaving all the water–water and protein–protein parameters unchanged. We find that a modest strengthening of protein–water interactions is sufficient to recover the correct dimensions of intrinsically disordered or unfolded proteins, as determined by direct comparison with small-angle X-ray scattering (SAXS) and Forster resonance energy transfer (FRET) data. The modification also results in more realistic protein-protein affinities, and average solvation free energies of model compounds which are more consistent with experiment. Most importantly, we show that this scaling...

Discrete solitons in photorefractive optically induced photonic lattices

Abstract: We demonstrate that optical discrete solitons are possible in appropriately oriented biased photorefractive crystals. This can be accomplished in optically induced periodic waveguide lattices that are created via plane-wave interference. Our method paves the way towards the observation of entirely new families of discrete solitons. These include, for example, discrete solitons in two-dimensional self-focusing and defocusing lattices of different group symmetries, incoherently coupled vector discrete solitons, discrete soliton states in optical diatomic chains, as well as their associated collision properties and interactions. We also present results concerning transport anomalies of discrete solitons that depend on their initial momentum within the Brillouin zone.

Methane-derived authigenic carbonates formed by subduction-induced pore-water expulsion along the Oregon/Washington margin

Abstract: Authigenic magnesian calcite, dolomite, and aragonite are precipitated in the uppermost terrigenous sediments of the Washington/Oregon accretionary prism by subduction-induced dewatering. These distinctive carbonates are methane-derived and occur at sites of concentrated pore-water expulsion. Unique biologic communities that subsist, at least indirectly, on methane (Suess et al., 1985) are also found at some of these sites. The methane, which is dominantly biogenic, is carried to the uppermost sediments of the prism by fluids and is oxidized by sulfate reducers before being incorporated into a carbonate cement. Carbonate precipitation occurs below the oxic layer, probably no deeper than several centimetres to a few metres below the seabed. Cementation may be induced by three factors: (1) increased carbonate alkalinity resulting from microbial sulfate reduction, (2) decreased σCO 2 solubility resulting from a pressure decrease when the pore water escapes the prism, and/or (3) the addition of Ca 2+ and Mg 2+ ions from sea water near the sediment/water interface. The convergent margin setting engenders precipitation of authigenic carbonates in several ways. Compressive stresses induce anomalously rapid compaction and dewatering rates, and they may cause overpressuring in migrating pore water, thereby delaying precipitation of carbonates until pressure is released near the sediment-water interface. Structural deformation of the accretionary prism creates pathways (such as fault zones), secondary fracture porosity, and dipping permeable layers (often exposed by mass movement) for efficient advection and expulsion of methane-enriched pore water. These characteristic conditions, which lead to the precipitation of methane-derived carbonates, may be found at other convergent margins.

Approaches for high internal quantum efficiency green InGaN light-emitting diodes with large overlap quantum wells

Abstract: Optimization of internal quantum efficiency (IQE) for InGaN quantum wells (QWs) light-emitting diodes (LEDs) is investigated. Staggered InGaN QWs with large electron-hole wavefunction overlap and improved radiative recombination rate are investigated for nitride LEDs application. The effect of interface abruptness in staggered InGaN QWs on radiative recombination rate is studied. Studies show that the less interface abruptness between the InGaN sub-layers will not affect the performance of the staggered InGaN QWs detrimentally. The growths of linearly-shaped staggered InGaN QWs by employing graded growth temperature grading are presented. The effect of current injection efficiency on IQE of InGaN QWs LEDs and other approaches to reduce dislocation in InGaN QWs LEDs are also discussed. The optimization of both radiative efficiency and current injection efficiency in InGaN QWs LEDs are required for achieving high IQE devices emitting in the green spectral regime and longer.