Publications by authors named "Katsuhisa Yoshida"

Localized impurities doped in the semiconductor substrate of nanostructure devices play anessential role in understanding and resolving transport and variability issues in device characteristics.Modeling discrete impurities under the framework of device simulations is, therefore, an urgent needfor reliable prediction of device performance via device simulations. In the present paper, we discussthe details of the physics associated with localized impurities in nanostructure devices, which areinherent, yet nontrivial, to any device simulation schemes: The physical interpretation and the roleof electrostatic Coulomb potential in device simulations are clarified.

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Article Synopsis
  • Photovoltaic generation has dramatically increased over the past ten years, now supplying about 1.7% of global electricity and emerging as a key player in the energy transition.
  • Advances in materials and production techniques have significantly contributed to this growth, but challenges remain in achieving clean, affordable energy through solar technology.
  • The Japan-French cooperation program, NextPV, explores innovative solar cell technologies, including multijunction and ultrathin cells, and focuses on developing printable materials like colloidal quantum dots.
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A large number of proteins in the vacuolar membrane (VM; tonoplast), including transporters and receptors, support the various functions of the vacuole. Molecular analysis of membrane proteins is an essential step in understanding how the vacuole operates but so far only a small number of tonoplast proteins have been identified at the molecular level. Accordingly, mutant lines with altered level of tonoplast proteins for characterizing their physiological roles have been developed sparsely.

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We report for the first time a successful fabrication and operation of an InAs/GaAs quantum dot based intermediate band solar cell concentrator photovoltaic (QD-IBSC-CPV) module to the IEC62108 standard with recorded power conversion efficiency of 15.3%. Combining the measured experimental results at Underwriters Laboratory (UL®) licensed testing laboratory with theoretical simulations, we confirmed that the operational characteristics of the QD-IBSC-CPV module are a consequence of the carrier dynamics via the intermediate-band at room temperature.

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The local distribution of both the vacuolar-type proton ATPase (V-ATPase) and the vacuolar-type proton pyrophosphatase (V-PPase), the main vacuolar proton pumps, was investigated in intact vacuoles isolated from Arabidopsis suspension-cultured cells. Fluorescent immunostaining showed that V-PPase was distributed evenly on the vacuolar membrane (VM), but V-ATPase localized to specific regions of the VM. We hypothesize that there may be membrane microdomains on the VM.

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The intracellular membrane dynamics of Arabidopsis cells under high salt treatment were investigated. When Arabidopsis was treated with high levels of NaCl in hydroponic culture, root tip cells showed rapid changes in the vacuolar volume, a decrease in the number of small acid compartments, active movement of vesicles and accumulation of Na(+) both in the central vacuole and in the vesicles around the main vacuole observed with the Na(+)-dependent fluorescence of Sodium Green. Detailed observation of Arabidopsis suspension-cultured cells under high salt treatment showed a similar pattern of response to that observed in root tip cells.

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The role of actin filaments in rhizoid morphogenesis was studied in Spirogyra. When the algal filaments were severed, new terminal cells started tip growth and finally formed rhizoids. Actin inhibitors, latrunculin B and cytochalasin D, reversibly inhibited the process.

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Spirogyra living in running water forms a rhizoid which anchors it to the substratum. Rhizoid differentiation can be induced in the laboratory by severing algal filaments. The terminal cell changes the growth mode from diffuse growth to tip growth, and finally differentiates to be a rhizoid.

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