SUMMARY Given their sessile nature, land plants must use various mechanisms to manage dehydration under water‐deficit conditions. Osmostress‐induced activation of the SNF1‐related protein kinase 2 (SnRK2) family elicits physiological responses such as stomatal closure to protect plants during drought conditions. With the plant hormone ABA receptors [PYR (pyrabactin resistance)/PYL (pyrabactin resistance‐like)/RCAR (regulatory component of ABA receptors) proteins] and group A protein phosphatases, subclass III SnRK2 also constitutes a core signaling module for ABA, and osmostress triggers ABA accumulation. How SnRK2 is activated through ABA has been clarified, although its activation through osmostress remains unclear. Here, we show that Arabidopsis ABA and abiotic stress‐responsive Raf‐like kinases (AtARKs) of the B3 clade of the mitogen‐activated kinase kinase kinase (MAPKKK) family are crucial in SnRK2‐mediated osmostress responses. Disruption of AtARKs in Arabidopsis results in increased water loss from detached leaves because of impaired stomatal closure in response to osmostress. Our findings obtained in vitro and in planta have shown that AtARKs interact physically with SRK2E, a core factor for stomatal closure in response to drought. Furthermore, we show that AtARK phosphorylates S171 and S175 in the activation loop of SRK2E in vitro and that Atark mutants have defects in osmostress‐induced subclass III SnRK2 activity. Our findings identify a specific type of B3‐MAPKKKs as upstream kinases of subclass III SnRK2 in Arabidopsis. Taken together with earlier reports that ARK is an upstream kinase of SnRK2 in moss, an existing member of a basal land plant lineage, we propose that ARK/SnRK2 module is evolutionarily conserved across 400 million years of land plant evolution for conferring protection against drought.
A systematic method based on the impedance technique to determine the optimal locations and shapes of multiple induced strain actuators bonded on a host structure in respect of the smallest power consumption is proposed. The mechanical efficiency in measuring the energy provided to the actuators and then transferred to the host structure is estimated by using the power factor which is expressed in terms of impedances of the host structure and the strain actuators. It provides an alternative besides optimization methods to decide where to bond the actuator and what the shape of the actuator should be. For an intelligent structure with multiple actuators, this proposed method provides accurate predictions of vibration response and mechanical efficiency due to the mass of the multiple actuators being included in the model. Numerical examples are presented to show the mass effect caused by the actuators on the power factor and to demonstrate how to determine the optimal bonding locations and configurations for the multiple actuators.
In order to get around the high and activated n-doping levels for ZnTe, the co-doping technique known as effective method to overcome the dopant compensation was explored. The co-doping concept is to introduce two oppositely polar atoms at the same time in a 2:1 ratio, forming metastable three-atom complexes located at adjacent crystal sites. In this study, two types of deposition process were considered to place the co-dopants at the intended site, and the co-doped ZnTe:(Al, N) layers were grown on (001) oriented ZnTe substrates by molecular beam epitaxy. From the low temperature PL spectra, the increase of Al activation was confirmed by using co-doping sequences, and the activation of N dopant was also confirmed for one doping sequence even thought the doping level was maintained the same.
Zincblende ZnMgCdS quaternary alloy layers were grown by molecular beam epitaxy. The ZnMgCdS alloy could lattice match to GaAs and could exhibit the band-gap energy of approximately 3 eV. Zn, Mg, and CdS were used as source materials. Incorporation of Mg was more effective compared with Zn in the alloy. Stabilizing the substrate temperature especially at the initial growth stage was crucial to obtain high quality layers. The epilayer was applied to the metal-semiconductor-metal photodetector, and the rejection rate above 10 3 have bean achieved.1 Introduction Recently, problems associated with the exposure to the UV-A ray has been reconsidered. The fabrication of visible blind UV-A sensors was extensively studied utilizing wide band gap II-VI compound epitaxial layers [1][2][3]. ZnMgCdS quaternary alloy is a II-II-II-VI compound which exhibits a room-temperature band-gap corresponding to the UV-A region (about 3 eV). The controllability of the alloy composition would be fairly easy since sulfur is the only anion in the alloy. Lattice matching to GaAs could be achieved regardless of Mg, and the band-gap would be around 3 eV when the Mg mole fraction would be about 10%. Disadvantages of Mg compounds include its hydroscopic nature and rock salt crystal structures [4]; the small mole fraction of Mg in the alloy is a notable advantage from the device application point of view. In this study, the ZnMgCdS alloy films were grown by molecular beam epitaxy (MBE) on (001) GaAs substrates and metal-semiconductor-metal (MSM) device structures were fabricated. The MSM device structure was focused in this study since the valence control of the crystal, which would be difficult for this alloy, could be ignored. Spectral response of the photoconductivity was characterized under various bias conditions.
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