High pressure growth and electron transport properties of superconducting SmFeAsO1-xHx single crystals

We report the single crystal growth and characterization of the highest Tc iron-based superconductor SmFeAsO1-xHx. Some sub-millimeter-sized crystals were grown using the mixture flux of Na3As + 3NaH + As at 3.0 GPa and 1473 K. The chemical composition analyses confirmed 10% substitution of hydrogen for the oxygen site (x = 0.10), however, the structural analyses suggested that the obtained crystal forms a multi-domain structure. By using the FIB technique we fabricated the single domain SmFeAsO0.9H0.10 crystal with the Tc of 42 K, and revealed the metallic conduction in in-plane (rhoab), while semiconducting in the out-of-plane (rhoc). From the in-plane Hall coefficient measurements, we confirmed that the dominant carrier of SmFeAsO0.9H0.10 crystal is an electron, and the hydride ion occupied at the site of the oxygen ion effectively supplies a carrier electron per iron following the equation: O2- = H- + e-.Comment: 4 figures, 2 table

Initial incorporation of phytoplankton into young ice in Saroma Ko lagoon, Hokkaido, Japan

The initial incorporation of phytoplankton into young ice was examined on February 25-28,1998 in Saroma Ko lagoon, Hokkaido, Japan to test our hypothesis that some physical selection would occur to establish the ice algal assemblages during the formation of young sea ice and the development of fast sea ice. An open pool (2×2m) was employed for the experiment. Young sea ice was collected for a 24hr experiment. Relative brine volume in the young sea ice might be related to air temperature. Incorporated contents of chlorophyll α, biogenic silica, particulate organic carbon and nitrogen were directly related to the relative brine volume. The larger than 2μm fractions of chlorophyll α and biogenic silica were 95% and 78%, respectively. The most abundant species incorporated into the young sea ice were Navicula transitans (33%) and Achnanthes taeniata (12%). Those species were originated from a water column where they were released from the bottom surface of seasonal sea ice in the vicinity of the experimental pool. Cell density of the incorporated phytoplankton ranged from 46 to 154 cells ml^ into the young sea ice and 17±5 cells ml^ in the sea water under the young sea ice. Those microscopic observations suggested the selective incorporation of phytoplankton into the young sea ice at the beginning of ice formation and it might accelerate selective development of establish the ice algal assemblages with the growth of fast sea ice

Rapid turnover of the CD3ζ chain independent of the TCR-CD3 complex in normal T cells

AbstractThe function of CD3ζ in the assembly and transport of the T cell receptor (TCR)-CD3 complex was analyzed in normal T cells. The ζ chain, but not other chains in the surface TCR complex, rapidly exchanged with newly synthesized ζ. Because ζ was expressed independently from the complex, the TCR complex may be transported to the surface along the ζ turnover pathway by association with ζ. These data suggest the dynamic nature of ζ metabolism and provide the evidence that a single component in a multisubunit receptor exhibits independent metabolism from the rest of the complex

Stability Calculation of Power Systems Having Shunt Loads

The small signal performance of a multimachine power system is described by a set of differential equations of the form ＝Ax. The analysis includes the effect of local shunt loads and margin of stability defined in the eigenvalue-plane. The construction of the A-matrix involves an equivalent circuit of a transmission network, a hybrid reference frame and an axis transformation based on Park's transformation. Once the A-matrix is obtained, standard computer programs may be used for studying the dynamic stability characteristics of the power system. Root-locus analysis is adapted to get information on the dynamic stability of a sample model

Infrared and Raman spectroscopic investigation of the reaction mechanism of cytochrome c oxidase

AbstractRecent progress in studies on the proton-pumping and O2 reduction mechanisms of cytochrome c oxidase (CcO) elucidated by infrared (IR) and resonance Raman (rR) spectroscopy, is reviewed. CcO is the terminal enzyme of the respiratory chain and its O2 reduction reaction is coupled with H+ pumping activity across the inner mitochondrial membrane. The former is catalyzed by heme a3 and its mechanism has been determined using a rR technique, while the latter used the protein moiety and has been investigated with an IR technique. The number of H+ relative to e− transferred in the reaction is 1:1, and their coupling is presumably performed by heme a and nearby residues. To perform this function, different parts of the protein need to cooperate with each other spontaneously and sequentially. It is the purpose of this article to describe the structural details on the coupling on the basis of the vibrational spectra of certain specified residues and chromophores involved in the reaction. Recent developments in time-resolved IR and Raman technology concomitant with protein manipulation methods have yielded profound insights into such structural changes. In particular, the new IR techniques that yielded the breakthrough are reviewed and assessed in detail. This article is part of a Special Issue entitled: Vibrational spectroscopies and bioenergetic systems

Dirac fermion reflector by ballistic graphene sawtooth-shaped npn junctions

We have realized a Dirac fermion reflector in graphene by controlling the ballistic carrier trajectory in a sawtooth-shaped npn junction. When the carrier density in the inner p-region is much larger than that in the outer n-regions, the first straight np interface works as a collimator and the collimated ballistic carriers can be totally reflected at the second zigzag pn interface. We observed clear resistance enhancement around the np+n regime, which is in good agreement with the numerical simulation. The tunable reflectance of ballistic carriers could be an elementary and important step for realizing ultrahigh-mobility graphene field effect transistors utilizing Dirac fermion optics in the near future

Mass, nitrogen content, and decomposition of woody debris in forest stands affected by excreta deposited in nesting colonies of Great Cormorant

First online: 14 March 2015Great Cormorant (Phalacrocorax carbo), a piscivorous bird, has established breeding colonies in a coniferous forest near Lake Biwa in central Japan. This study investigated the possible effects of the colony’s excreta on the mass, nitrogen (N) content, and decomposition of woody debris. Study plots were established in forest stands representing four stages from breeding colony establishment to post-abandonment. The mass of fallen branches (diameter 1–5 cm) and coarse woody debris (logs, snags, and stumps; diameter ≥10 cm) was greater in forest stands colonized by Cormorants than a control stand never colonized by Cormorants. This was primarily attributed to Cormorant activity that caused increased mortality of standing trees and by Cormorants breaking branches for nesting materials. Nitrogen content of branches and logs that had fallen to the forest floor was negatively correlated with the relative density of wood. Nitrogen content of branches was consistently higher (at a given value of relative density) in the colonized stands than in the control stand. The increase of branch N content was possibly caused by the incorporation of N into decomposing branches with excreta-derived N supplied as throughfall and/or soil solution. The mean value of 2-year mass loss of recently dead branches and logs was significantly greater for woody debris in the smallest diameter class but was not significantly different among the forest stands. This suggests that the excessive supply of excreta-derived N and concomitant enrichment of N in soil had negligible effects on the initial stages of decomposition of woody debris