skip to main content

Title: X-ray computed tomography to predict soil N 2 O production via bacterial denitrification and N 2 O emission in contrasting bioenergy cropping systems
Award ID(s):
1832042 1637653 1027253
Author(s) / Creator(s):
 ;  ;  ;  ;  ;  
Publisher / Repository:
Date Published:
Journal Name:
GCB Bioenergy
Page Range / eLocation ID:
894 to 909
Medium: X
Sponsoring Org:
National Science Foundation
More Like this
  1. The thermal stability of n/n + β -Ga 2 O 3 epitaxial layer/substrate structures with sputtered ITO on both sides to act as rectifying contacts on the lightly doped layer and Ohmic on the heavily doped substrate is reported. The resistivity of the ITO deposited separately on Si decreased from 1.83 × 10 −3 Ω.cm as-deposited to 3.6 × 10 −4 Ω.cm after 300 °C anneal, with only minor reductions at higher temperatures (2.8 × 10 −4 Ω.cm after 600 °C anneals). The Schottky barrier height also decreased with annealing, from 0.98 eV in the as-deposited samples to 0.85 eV after 500 °C annealing. The reverse breakdown voltage exhibited a negative temperature coefficient of −0.46 V.C −1 up to an annealing temperature of 400 °C and degraded faster at higher temperatures. Transmission Electron Microscopy showed significant reaction at the ITO and Ga 2 O 3 interface above 300 °C, with a very degraded contact stack after annealing at 500 °C. 
    more » « less
  2. Abstract

    The ratio of O to N2number densities (O/N2) at different altitudes is an important parameter in describing thermospheric neutral composition changes and their effects on the ionosphere during geomagnetic storms. However, storm‐induced vertical variations in O/N2and its dependence on the O and N2perturbations are still not fully understood. Here, the Thermosphere/Ionosphere Electrodynamics General Circulation Model simulations were used to investigate the responses of thermospheric composition at different pressure levels to the super geomagnetic storm occurred on November 20 and 21 in 2003. Our analysis shows that the behaviors of O/N2perturbations on different pressure levels are similar above ∼180 km altitude. In the middle and low thermosphere of below ∼300 km, the storm‐time O/N2decrease is mainly caused by a large reduction of O number density. However, N2enhancement plays a vital role in O/N2decreases in the upper thermosphere. The O/N2enhancement is mainly attributed to the N2decreases at all pressure levels. The changes of O and N2number densities at a constant pressure level can be explained by the perturbations of their mass mixing ratio (mmr) and total mass density (ρ). The regions of the O/N2decrease are characterized by the O mmr decrease and N2mmr enhancement, whereas the regions of the O/N2increase are characterized by the O mmr increase and N2mmr decrease. Theρvalue that shows the decrease globally at most pressure levels during the storm either enhance or reduce the O and N2perturbations.

    more » « less