Yuki Nakano

GaAs-Based Nanowire Devices with Multiple Asymmetric Gates for Electrical Brownian Ratchets

GaAs-based nanowire devices having multiple asymmetric gates for electrical Brownian ratchets were fabricated and characterized. From three-dimensional potential simulation results and current–voltage characteristics, we confirmed the formation of the asymmetric potential in our device design. Direct current was generated at room temperature by repeatedly switching the potential in a multiple-asymmetric-gate device on and off. Such current was not observed in either a single-asymmetric-gate device or a multiple-symmetric-gate device. The current direction and input frequency dependences of the net current indicated that the observed current was generated by the flashing-ratchet mechanism.

Systematic Investigation of c-Axis Tilt in GaN and AlGaN Grown on Vicinal SiC(0001) Substrates

High-resolution X-ray diffraction measurements of GaN and AlGaN grown on 4H- and 6H-SiC(0001) vicinal substrates with misorientation angles of up to 9° are presented. Growth of (Al)GaN was carried out by plasma-assisted molecular beam epitaxy. The c-axis tilt, i.e., inclination of the (Al)GaN c-axis relative to that of SiC, was systematically investigated. The inclination angle clearly depended on the SiC substrate misorientation angle, while it was independent of the (Al)GaN growth temperature, SiC polytype, and substrate misorientation direction. The behavior observed for both GaN and AlGaN is in excellent agreement with the model proposed previously by Nagai for the InGaAs/GaAs system.

Role of Orography, Diurnal Cycle, and Intraseasonal Oscillation in Summer Monsoon Rainfall over the Western Ghats and Myanmar Coast

AbstractRainfall over the coastal regions of western India [Western Ghats (WG)] and Myanmar [Arakan Yoma (AY)], two regions experiencing the heaviest rainfall during the Asian summer monsoon, is examined using a Tropical Rainfall Measuring Mission (TRMM) Precipitation Radar (PR) dataset spanning 16 years. Rainfall maxima are identified on the upslope of the WG and the coastline of AY, in contrast to the offshore locations observed in previous studies. Continuous rain with slight nocturnal and afternoon–evening maxima occurs over the upslope of the WG, while an afternoon peak over the upslope and a morning peak just off the coast are found in AY, resulting in different locations of the rainfall maxima for the WG (upslope) and AY (coastline). Large rainfall amounts with small diurnal amplitudes are observed over the WG and AY under strong environmental flow perpendicular to the coastal mountains, and vice versa. Composite analysis of the boreal summer intraseasonal oscillation (BSISO) shows that the rain an...

Tyr34 in PSII-L Protein is Essential for the Oxidation of Tyr-Z in PSII

It is well established that all of the redox components which participate in the light induced electron transfer in the PSII are located in a heterodimer of two polypeptides denoted as D1 and D2. However, a minimal size preparation of PSII isolated from higher plants composed of D1/D2/Cytb-559/PSII-I proteins gives a spin-polarized triplet signal upon low temperature illumination which is a result of charge recombination between P680+ and Pheo−, but does not give EPR signal exhibiting the formation of Tyr-Z+ upon illumination, indicating the electron transfer succeeding to the photoinduced primary charge separation to be inhibited in the minimal size PSII preparation. This was a kind of mystery which had remained for long to be solved, because Tyr-Z and D present in the complex. Recently, we reported that PSII-L protein is involved in the donor side electron transfer of PSII (1). PSII-L encoded by psbL gene in plastid DNA of the higher plants is a component of the PS II reaction center complex. This protein consists of 37 amino acid residues and has a single putative transmembrane a-helix in its carboxyl-terminal region (2).