Current-driven resonant excitation of magnetic vortices

A magnetic vortex core in a ferromagnetic circular nanodot has a resonance frequency originating from the confinement of the vortex core. By the micromagnetic simulation including the spin-transfer torque, we show that the vortex core can be resonantly excited by an ac (spin-polarized) current through the dot and that the resonance frequency can be tuned by the dot shape. The resistance measurement under the ac current successfully detects the resonance at the frequency consistent with the simulation.     

The electronic structure and magnetic property of μ-hydroxo bridged manganese porphyrin dimer

The electronic structure and effective exchange integrals (J _ab) between two manganese (III) ions of porphyrin dimer (PPMn(III)–OH–Mn(III)PP) were examined by using unrestricted hybrid DFT (UHDFT) methods. The dependence of J_ab on bond angle between two manganese ( Mn–OH–Mn) is also calculated to elucidate orbital overlap effect for J_ab value in the system. Natural orbital analysis is performed to explain the overlap effect in terms of the instability of the π, σ and δ orbitals by using diradical character.     

Study of γ d → π + π − d Reaction in an Energy Region of 0.67 ≤ E γ ≤ 1.08 GeV

Double charged pion photoproductions from the deuteron have been studied at Research Center for Electron Photon Science (ELPH), Tohoku University. Tagged photon beams in an energy range of 0.67 ≤ E _γ ≤ 1.08 GeV were impinged on the liquid deuteron target. Produced charged particles were observed with the Neutral Kaon Spectrometer2 (NKS2). The γ d → π ⁺ π ^? d process was clearly separated among the three charged tracks. We obtained the photon energy dependence of the normalized yields of this process.     

Study of Strangeness Photoproduction on the Neutron in the Threshold Region

Photoproduction of the neutral kaon on the deuteron has been investigated at the Research Center for Electron Photon Science, Tohoku University. We constructed the Neutral Kaon Spectrometer-2 for the detection of charged particles from the decay of the neutral kaon and the hyperon. We obtained a momentum distribution of K ⁰ with the inclusive measurement. It was consistent with the previous measurement. The total cross section of γ + d → K ⁰ + Λ + p was estimated from the measured integral cross section of γ + d → Λ + X. The total cross section with respect to the photon energy was compared with the theoretical calculations. It favored the Saclay-Lyon A model calculation with the ratio of the neutral to charged coupling constants of the axial-vector meson, K ₁, as ~ ?1.5. The energy dependence and the magnitude of the total cross section were similar to the total cross section of γ + p → K ⁺ Λ.     

Imaging mass spectrometry of gold nanoparticles in a tissue section as an immunohistochemical staining mass probe

For analysis of low abundance peptides in a tissue section, immunohistochemical staining through antibody‐antigen interaction is a usual technique. The antibody is conjugated with a probe moiety that aids in highly sensitive detection. Gold nanoparticles, which show excellent chemical stability and variation of surface modifications, are expected to act as a sensitive mass probe to desorb gold ions (Au⁺, Au₂⁺, Au₃⁺) that are distinguishable from fragment ions from organic molecules. Here, green fluorescent proteins (GFP) in a tissue section of a transgenic zebrafish were detected by the gold mass probe conjugated with antibodies. Due to the efficient ionization and desorption of gold ions, imaging mass spectrometry of Au₂⁺ ions indicated the distribution of gold nanoparticles stained in a tissue section, and the mass signal distribution was consistent with the area where the GFP‐expressing cells were distributed. Conventional immunofluorescence techniques showed intense autofluorescence that come from intrinsic fluorophores in the tissue section. In contrast, the gold nanoparticles acted as an immunostaining mass probe that displayed significantly lower background signals.     

Stereodynamics in dissociative adsorption of NO on Si(111)

We report results of our study on the surface-temperature dependence of the steric effect in the dissociative adsorption of NO on Si(111)-(7x7). Data presented here show that, at an incident energy of 58 meV, the reactive sticking probability for the N-end collision is larger than that for the O-end collision. Furthermore, this steric preference is quite sensitive to the surface temperature and the surface coverage. This study shows that the transient surface trapping into a shallow precursor well plays a key role in the stereodynamics of the dissociative adsorption at the low energy region.     

Fabrication of micro-structure on glass surface using micro-indentation and wet etching process

In order to improve the new micro-fabrication technology using micro-indentation and wet etching, in which the etching rate drastically decrease at the indented area and consequently micro-structure can be formed on the glass surface, the effect of the applying load on the etching rate change was investigated. The extent of the etching rate change was found to be almost constant irrespective of the amount of the applying load. Therefore, the height of the structure could be controlled simply by the etching depth as far as the densified portion remains beneath the glass surface. And some example micro-patterns were fabricated in this process. Various kinds of indentation methods were employed, including scanning a pointed tool under a load and wet abrasive blast. The patterns can be freely drawn by the use of numerical control (NC) machine. Mold pattern can be also applied, which enables drawing many lines simultaneously. In every method, the heights of the patterns were confirmed to be very uniform. This new type of the micro-fabrication method was referred to as “SMIL (Stress Masked Image Lithography)”.     

Syntheses of thallusin analogues and their algal morphogenesis-inducing activities

Thallusin is the only known natural product that induces cell differentiation followed by formation of a thallus during the growth of green macroalgae such as Monostroma and Ulva. Herein, various thallusin analogues based on the terpen skeleton were synthesized to study the structure?activity relationships of thallusin. The potency of the synthetic analogues was investigated in an experimental assay, which demonstrated that the 19-methyl group in thallusin is essential for potent morphogenesis-inducing activity.     

Coadsorbed H and CO interaction on platinum

The behavior of hydrogen near a platinum-surface-adsorbed carbon monoxide molecule is described using a potential energy term constructed from density functional theory. A clear nonattractive interaction of hydrogen with CO is confirmed, most notably with oxygen, which retains its strong H-repulsive traits in the Pt-bound CO case. Inhibiting effects of CO greater than what is expected from simple adsorption site exclusion are discussed with regard to adsorption/desorption and mobility on platinum, as well as possibilities of COH and HCO formation.     

Atomic alignment effect on the branching to ArCl* and CCl2* formation in the reaction of oriented Ar(3P2,MJ=2) + CCl4

Atomic alignment effects for the formation of ArCl*(C) and CCl2*(A) in the reaction of Ar((3)P 2) + CCl 4 have been measured by using an oriented Ar( (3)P2, M J=2) beam at a collision energy of 0.08 eV. The emission intensity for ArCl*(C) and CCl2*(A) has been measured as a function of the magnetic orientation field direction in the collision frame. A significant atomic alignment effect is observed for the atom transfer process [ArCl*(C) formation]. Formation of ArCl*(C) is modestly enhanced when the electron angular momentum of the Ar((3)P 2) reactant is aligned along the relative velocity vector, while the excitation transfer process [CCl2*(A) formation] shows little alignment effect.