Abscisic acid (ABA) is a plant hormone that mediates abiotic stress tolerance and regulates growth and development. ABA binds to members of the PYL/RCAR ABA receptor family that initiate signal transduction inhibiting type 2C protein phosphatases. Although crosstalk between ABA and the hormone Jasmonic Acid (JA) has been shown, the molecular entities that mediate this interaction have yet to be fully elucidated. We report a link between ABA and JA signaling through a direct interaction of the ABA receptor PYL6 (RCAR9) with the basic helix-loop-helix transcription factor MYC2. PYL6 and MYC2 interact in yeast two hybrid assays and the interaction is enhanced in the presence of ABA. PYL6 and MYC2 interact in planta based on bimolecular fluorescence complementation and co-immunoprecipitation of the proteins. Furthermore, PYL6 was able to modify transcription driven by MYC2 using JAZ6 and JAZ8 DNA promoter elements in yeast one hybrid assays. Finally, pyl6 T-DNA mutant plants show an increased sensitivity to the addition of JA along with ABA in cotyledon expansion experiments. Overall, the present study identifies a direct mechanism for transcriptional modulation mediated by an ABA receptor different from the core ABA signaling pathway, and a putative mechanistic link connecting ABA and JA signaling pathways.
Analyzing the dynamics of trapped electron fluxes in the Earth's outer radiation belt is a complex task, due to the presence of insufficiently known parameters and the long runtimes of multi-dimensional radiation belt codes, preventing a thorough examination of dependencies on all parameters. Here, we present an approximate eigenfunction modeling of whistler-mode wave-driven electron pitch-angle diffusion, slightly generalized compared to previous work. This new model can approximately describe, in an easy, flexible, and fast way, both the asymptotic electron pitch-angle distribution (PAD) at all pitch angles and its temporal evolution toward this final state, in both weak and strong diffusion regimes, in the presence of a finite, time-varying electron source. In this model, wave-driven pitch-angle diffusion is assumed to prevail over energy diffusion and radial diffusion, limiting its applicability to the plasmasphere or intervals of smooth decay of the electron flux outside the plasmasphere, during moderately active periods. We propose a new method, based on this model, for estimating the energy spectrum and temporal variation of the electron source. We investigate the dynamics of the electron flux measured by the Van Allen Probes and Arase spacecraft during two events in 2018 and 2022 in the outer radiation belt. We demonstrate that the new model can reproduce the evolution of the measured electron flux and of its PAD, provided that the magnitude of diffusion rates is normalized to the observed decay timescale in the 300-600 keV range and that a finite electron source term is included below 300 keV.
Optical emission spectroscopy has been used to study the effects of cryogenic substrate cooling during etching of SiO2 in CF4/H2 plasma admixtures in a low-pressure, industrial grade etching device. The absolute densities of atomic F, O and H, and relative densities of OH and CO molecules were obtained. All species and etch rates showed significant increase once the substrate temperature reached below -40 degrees C, with O and H increasing overall by 5.5 & times; and 2 & times; at -60 degrees C, respectively, except for F which increased only by 0.6 & times; due to scavenging by H atoms. Under fixed cooling, the density variation of F and H behaved similarly to the ambient case, whereas O density reduction was delayed until much higher H2 contents, showing that etching could continue under these conditions. Thus, in addition to enhanced etch rates, cryogenic cooling clearly affects the composition of the plasma. By studying the OH emission, a rise in its hot rotational temperature stems from dissociative recombination of H3O+ and is indicative of adsorbed HF and H2O at cryogenic temperatures dissociating at the substrate surface, resulting in the faster etching.
Abstract Widespread household use of solid fuels releases massive amounts of carbonaceous aerosols in developing countries. Assessment of their roles in meteorology and climate change is considered low confidence by the Intergovernmental Panel on Climate Change. Here, we leverage real‐world measurements to constrain the radiative absorption of light‐absorbing organic aerosols (i.e., brown carbon, BrC) from household coal and biofuel combustion within chemistry‐climate simulations. We determine the mass absorption efficiencies ranging from 0.7 to 3.2 m2 g−1 for coal and 2.1–5.8 m2 g−1 for biofuel, with an Absorption Ångström Exponent of about 5. Our improved simulations show that despite an ∼30% reduction from photobleaching, BrC radiative absorption still amounts to 16–49% of black carbon absorption in China, 2–7 times that simulated by commonly used parameterizations. Such importance of household‐derived BrC also exists in South Asia and Central Africa. Our results help reevaluate the intricate effects of anthropogenic emissions on weather and climate.
This study investigates the formation and soot removal properties of four composite materials derived from alloy glasses in the system of Zr-Pd-Pt-Ce. Amorphous Zr65Pd35, Zr65Pd30Pt5, Zr60Pd35Ce5, and Zr60Pd30Pt5Ce5 were subjected to a heat treatment at 800 degrees C for 3 h in air, resulting in the formation of composites containing PdO, Pd and a mixture of tetragonal and monoclinic ZrO2 phases. Their microstructure was identified as composites in which PdO (Pd) precipitates are were dispersed in a ZrO2 matrix. The oxidation of soot over the composites was initiated at lower temperatures, reaching the completion of removal at approximately 600 degrees C, which was superior to that of non-catalytic soot combustion. The sequence in which the removal temperatures decreased was as follows: Zr65Pd35 > Zr60Pd35Ce5 > Zr60Pd25Pt5Ce5 > Zr65Pd30Pt5. The microstructure emerges as the predominant factor influencing soot oxidation activity, where the oxidation reaction rate was mainly governed by the interface length between PdO and ZrO2. The present results identified a novel bulk-type catalytic composite material, which was derived by a simple process from alloy glasses for the purpose of low-temperature soot oxidation.
