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Volume 89, Issue 1
Displaying 1-5 of 5 articles from this issue
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Reviews
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Toshinori SUZUKI2013 Volume 89 Issue 1 Pages 1-15
Published: January 11, 2013
Released on J-STAGE: January 11, 2013
JOURNAL FREE ACCESSPolyatomic molecules have several electronic states that have similar energies. Consequently, their chemical dynamics often involve nonadiabatic transitions between multiple potential energy surfaces. Elucidating the complex reactions of polyatomic molecules is one of the most important tasks of theoretical and experimental studies of chemical dynamics. This paper describes our recent experimental studies of the multidimensional multisurface dynamics of polyatomic molecules based on two-dimensional ion/electron imaging. It also discusses ultrafast photoelectron spectroscopy of liquids for elucidating nonadiabatic electronic dynamics in aqueous solutions.
(Communicated by Hiroo INOKUCHI, M.J.A.)View full abstractDownload PDF (1567K) -
Tatsuhiko YAGI, Yoshiki HIGUCHI2013 Volume 89 Issue 1 Pages 16-33
Published: January 11, 2013
Released on J-STAGE: January 11, 2013
JOURNAL FREE ACCESSHydrogenases are microbial enzymes which catalyze uptake and production of H2. Hydrogenases are classified into 10 classes based on the electron carrier specificity, or into 3 families, [NiFe]-family (including [NiFeSe]-subfamily), [FeFe]-family and [Fe]-family, based on the metal composition of the active site. H2 is heterolytically cleaved on the enzyme (E) to produce EHaHb, where Ha and Hb have different rate constants for exchange with the medium hydron. X-ray crystallography unveiled the three-dimensional structures of hydrogenases. The simplest [NiFe]-hydrogenase is a heterodimer, in which the large subunit bears the Ni-Fe center buried deep in the protein, and the small subunit bears iron-sulfur clusters, which mediate electron transfer between the Ni-Fe center and the protein surface. Some hydrogenases have additional subunit(s) for interaction with their electron carriers. Various redox states of the enzyme were characterized by EPR, FTIR, etc. Based on the kinetic, structural and spectroscopic studies, the catalytic mechanism of [NiFe]-hydrogenase was proposed to explain H2-uptake, H2-production and isotopic exchange reactions.
(Communicated by Shigekazu NAGATA, M.J.A.)View full abstractDownload PDF (3324K) -
Masahiko ISOBE2013 Volume 89 Issue 1 Pages 34-50
Published: January 11, 2013
Released on J-STAGE: January 11, 2013
JOURNAL FREE ACCESSIn this paper, a systematic, overall view of theories for periodic waves of permanent form, such as Stokes and cnoidal waves, is described first with their validity ranges. To deal with random waves, a method for estimating directional spectra is given. Then, various wave equations are introduced according to the assumptions included in their derivations. The mild-slope equation is derived for combined refraction and diffraction of linear periodic waves. Various parabolic approximations and time-dependent forms are proposed to include randomness and nonlinearity of waves as well as to simplify numerical calculation. Boussinesq equations are the equations developed for calculating nonlinear wave transformations in shallow water. Nonlinear mild-slope equations are derived as a set of wave equations to predict transformation of nonlinear random waves in the nearshore region. Finally, wave equations are classified systematically for a clear theoretical understanding and appropriate selection for specific applications.
(Communicated by Kiyoshi HORIKAWA, M.J.A.)View full abstractDownload PDF (425K)
Original Articles
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Arnaud METSUE, Taku TSUCHIYA2013 Volume 89 Issue 1 Pages 51-58
Published: January 11, 2013
Released on J-STAGE: January 11, 2013
JOURNAL FREE ACCESSWe investigate the shear response of possible slip systems activated in pure and Fe-bearing MgSiO3 post-perovskite (PPv) through ab initio generalized stacking fault (GSF) energy calculations. Here we show that the [100](001) slip system has the easiest response to plastic shear among ten possible slip systems investigated. Incorporation of Fe2+ decreases the strength of all slip systems but does not change the plastic anisotropy style. Therefore, pure and Fe-bearing MgSiO3 PPv should demonstrate similar LPO patterns with a strong signature of the [100](001) slip system. An aggregate with this deformation texture is expected to produce a VSH > VSV type polarization anisotropy, being consistent with seismological observations.
(Communicated by Ikuo KUSHIRO, M.J.A.)View full abstractDownload PDF (672K) -
Yoshiki TSUCHIYA, Itsunari MINAMI, Hiroshi KADOTANI, Takeshi TODO, Eis ...2013 Volume 89 Issue 1 Pages 59-65
Published: January 11, 2013
Released on J-STAGE: January 11, 2013
JOURNAL FREE ACCESSAccumulating evidence indicates that ERK MAP kinase signaling plays an important role in the regulation of the circadian clock, especially in the clock-resetting mechanism in the suprachiasmatic nucleus (SCN) in mammals. Previous studies have also shown that ERK phosphorylation exhibits diurnal variation in the SCN. However, little is known about circadian regulation of ERK signaling in peripheral tissues. Here we show that the activity of Ras/ERK signaling exhibits circadian rhythms in mouse liver. We demonstrate that Ras activation, MEK phosphorylation, and ERK phosphorylation oscillate in a circadian manner. As the oscillation of ERK phosphorylation is lost in Cry1/Cry2 double-knockout mice, Ras/ERK signaling should be under the control of the circadian clock. Furthermore, expression of MAP kinase phosphatase-1 (Mkp-1) shows diurnal changes in liver. These results indicate that Ras/ERK signaling is strictly regulated by the circadian clock in liver, and suggest that the circadian oscillation of the activities of Ras, MEK, and ERK may regulate diurnal variation of liver function and/or homeostasis.
(Communicated by Shigekazu NAGATA, M.J.A.)View full abstractDownload PDF (371K)
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