Browsing by Author "Garcia, Carlos"

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    Global ecological predictors of the soil priming effect
    Bastida, Felipe; Garcia, Carlos; Fierer, Noah; Eldridge, David J.; Bowker, Matthew A.; Abades, Sebastian R.; Alfaro, Fernando D.; Berhe, Asmeret Asefaw; Cutler, Nick A.; Gallardo, Antonio; Garcia-Velazquez, Laura; Hart, Stephen C.; Hayes, Patrick E.; Hernández, Teresa; Hseu, Zeng-Yei; Jehmlich, Nico; Kirchmair, Martin; Lambers, Hans; Neuhauser, Sigrid; Pena-Ramirez, Victor M.; Perez, Cecilia A.; Reed, Sasha C.; Santos, Fernanda; Siebe, Christina; Sullivan, Benjamin W.; Trivedi, Pankaj; Vera, Alfonso; Williams, Mark A.; Moreno, Jose Luis; Delgado-Baquerizo, Manuel (Springer Nature, 2019-08-02)
    Identifying the global drivers of soil priming is essential to understanding C cycling in terrestrial ecosystems. We conducted a survey of soils across 86 globally-distributed locations, spanning a wide range of climates, biotic communities, and soil conditions, and evaluated the apparent soil priming effect using C-13-glucose labeling. Here we show that the magnitude of the positive apparent priming effect (increase in CO2 release through accelerated microbial biomass turnover) was negatively associated with SOC content and microbial respiration rates. Our statistical modeling suggests that apparent priming effects tend to be negative in more mesic sites associated with higher SOC contents. In contrast, a single-input of labile C causes positive apparent priming effects in more arid locations with low SOC contents. Our results provide solid evidence that SOC content plays a critical role in regulating apparent priming effects, with important implications for the improvement of C cycling models under global change scenarios.
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    Photoluminescence Study of Carrier Localization and Recombination in Nearly Strain-Balanced Nonpolar InGaN/AlGaN Quantum Wells
    Cao, Yang; Dzuba, Brandon; Magill, Brenden A.; Senichev, Alexander; Trang Nguyen; Diaz, Rosa E.; Manfra, Michael J.; McGill, Stephen; Garcia, Carlos; Khodaparast, Giti A.; Malis, Oana (Wiley-V C H, 2022-02-16)
    Temperature-dependent continuous-excitation and time-resolved photoluminescence are studied to probe carrier localization and recombination in nearly strain-balanced m-plane In0.09Ga0.91N/Al0.19Ga0.81N multi-quantum wells grown by plasma-assisted molecular-beam epitaxy. An average localization depth of 21 meV is estimated for the undoped sample. This depth is much smaller than the reported values in polar structures and m-plane InGaN quantum wells. As part of this study, temperature and magnetic field dependence of time-resolved photoluminescence is performed. At 2 K, an initial fast decay time of approximate to 0.3 ns is measured for both undoped and doped structures. The undoped sample also exhibits a slow decay component with a time scale of 2.2 ns. The existence of two relaxation paths in the undoped structure can be attributed to different localization centers. The fast relaxation decays are relatively insensitive to external magnetic fields, while the slower relaxation time constant decreases significantly with increasing magnetic fields. The fast decay time scale in the undoped sample is likely due to indium fluctuations in the quantum well. The slow decay time may be related to carrier localization in the barriers. The addition of doping leads to a single fast decay time likely due to stronger exciton localization in the InGaN quantum wells.