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.

Coupling of rock uplift and river incision in the Namche Barwa–Gyala Peri massif, Tibet

Abstract: Geodynamic modeling demonstrates the strong potential for erosion to influence the pattern and style of deformation in active mountain belts, but field studies yield conflicting views on the importance of erosion in influencing orogenesis. Here we compare patterns in river power, inferred excess fluvial-transport capacity, topographic relief, precipitation, and mineral-cooling ages to assess the coupling between surface erosion and rock uplift within the vicinity of the Namche Barwa–Gyala Peri massif, an active antiformal structure within the eastern Himalayan syntaxis. Our rich and dense data set reveals a tight spatial correspondence of fluvial incision potential, high relief, and young cooling ages. The spatial coincidence is most easily explained by a sustained balance between rock uplift and denudation driven by river incision over at least the last ∼1 m.y. The Yarlung Tsangpo–Brahmaputra River is the largest and most powerful river in the Himalaya, and two lines of evidence point to its active role in the dynamic interaction of local erosion, rock uplift, thermal weakening of the lithosphere, and deformation: (1) Whereas along the rest of the Himalayan front, high relief and high rock uplift rates are essentially continuous, the high relief and rapid exhumation in the syntaxis is restricted to a “bull's-eye” pattern exactly where the largest river in the Himalaya, the Yarlung Tsangpo–Brahmaputra, has the most energy per unit area available to erode its channel and transport sediment. (2) The location of rapid incision on the Yarlung Tsangpo–Brahmaputra has been pinned for at least 1 m.y., and without compensatory uplift of the Namche Barwa–Gyala Peri massif during this time the river would have eroded headward rapidly, incising deeply into Tibet.

TESS Discovery of a Transiting Super-Earth in the pi Mensae System

Abstract: We report the detection of a transiting planet around π Men (HD 39091), using data from the Transiting Exoplanet Survey Satellite (TESS). The solar-type host star is unusually bright (V = 5.7) and was already known to host a Jovian planet on a highly eccentric, 5.7-year orbit. The newly discovered planet has a size of 2.04 ± 0.05 R⊕ and an orbital period of 6.27 days. Radial-velocity data from the HARPS and AAT/UCLES archives also displays a 6.27-day periodicity, confirming the existence of the planet and leading to a mass determination of 4.82±0.85 M⊕. The star's proximity and brightness will facilitate further investigations, such as atmospheric spectroscopy, asteroseismology, the Rossiter-McLaughlin effect, astrometry, and direct imaging.

Perchlorate Reduction by Nanoscale Iron Particles

Abstract: We report herein the near complete reduction of perchlorate (ClO $$_{4}^{-}$$ ) to chloride by nanoscale iron particles. The nanoparticles also reduce chlorate (ClO $$_{3}^-$$ ), chlorite (ClO $$_{2}^-$$ ) and hypochlorite (ClO $$^{-}$$ ) to chloride. No reaction was observed with microscale iron powder under identical conditions. The temperature sensitivity of the perchlorate-nanoparticle reaction is evidenced by progressively increasing rate constant values of 0.013, 0.10, 0.64 and 1.52 mg perchlorate per g nanoparticles per hour (mg-g-1-hr-1), respectively, at temperatures of 25, 40, 60 and 75°C. The activation energy of perchlorate-iron reaction was calculated to be 79.02 ± 7.75 kJ/mole. Despite favorable thermodynamics, the relatively large activation energy for this reaction suggests that perchlorate reduction is limited by the slow kinetics. The nanoscale iron particles may represent a potential treatment method for perchlorate-contaminated water.

From Board Composition to Corporate Environmental Performance Through Sustainability-Themed Alliances

Abstract: A growing body of work suggests that the presence of women and of independent directors on boards of directors is associated with higher corporate environmental performance. However, the mechanisms linking board composition to corporate environmental performance are not well understood. This study proposes and empirically tests the mediating role of sustainability-themed alliances in the relationship between board composition and corporate environmental performance. Using the population of public oil and gas firms in the United States as the sample, the study relies on renewable energy alliances to measure sustainability-themed alliances and longitudinally analyzes lagged data for independent and control variables. The study found that (1) the higher the representation of women on a firm’s board, the more likely the firm is to form sustainability-themed alliances, and (2) the higher the representation of independent directors on a firm’s board, the more likely the firm is to form sustainability-themed alliances. Such alliances, in turn, positively contribute to corporate environmental performance. This paper discusses the study’s contributions to the board composition-social performance literature.

TDP-43 α-helical structure tunes liquid–liquid phase separation and function

Abstract: Liquid-liquid phase separation (LLPS) is involved in the formation of membraneless organelles (MLOs) associated with RNA processing. The RNA-binding protein TDP-43 is present in several MLOs, undergoes LLPS, and has been linked to the pathogenesis of amyotrophic lateral sclerosis (ALS). While some ALS-associated mutations in TDP-43 disrupt self-interaction and function, here we show that designed single mutations can enhance TDP-43 assembly and function via modulating helical structure. Using molecular simulation and NMR spectroscopy, we observe large structural changes upon dimerization of TDP-43. Two conserved glycine residues (G335 and G338) are potent inhibitors of helical extension and helix-helix interaction, which are removed in part by variants at these positions, including the ALS-associated G335D. Substitution to helix-enhancing alanine at either of these positions dramatically enhances phase separation in vitro and decreases fluidity of phase-separated TDP-43 reporter compartments in cells. Furthermore, G335A increases TDP-43 splicing function in a minigene assay. Therefore, the TDP-43 helical region serves as a short but uniquely tunable module where application of biophysical principles can precisely control assembly and function in cellular and synthetic biology applications of LLPS.