Reduction of elemental selenium by samarium diiodide: Selective synthesis of diorganyl selenides and diselenides

The reduction of elemental selenium by samarium diiodide led to selective formation of selenolate anion species (Se²⁻ and Se₂²⁻), the alkylation of which provided dialkyl selenides and diselenides, respectively, in excellent yields.     

Time operators for quantum walks

Letters in Mathematical Physics - We study time operators for discrete-time quantum systems. Quantum walks are typical examples. We construct time operators for one-dimensional homogeneous quantum...     

A new set of atomic radii for accurate estimation of solvation free energy by Poisson–Boltzmann solvent model

The Poisson–Boltzmann implicit solvent (PB) is widely used to estimate the solvation free energies of biomolecules in molecular simulations. An optimized set of atomic radii (PB radii) is an important parameter for PB calculations, which determines the distribution of dielectric constants around the solute. We here present new PB radii for the AMBER protein force field to accurately reproduce the solvation free energies obtained from explicit solvent simulations. The presented PB radii were optimized using results from explicit solvent simulations of the large systems. In addition, we discriminated PB radii for N‐ and C‐terminal residues from those for nonterminal residues. The performances using our PB radii showed high accuracy for the estimation of solvation free energies at the level of the molecular fragment. The obtained PB radii are effective for the detailed analysis of the solvation effects of biomolecules. © 2014 The Authors Journal of Computational Chemistry Published by Wiley Periodicals, Inc.     

Color removal method considering perceived lightness

Optical Review - A novel color removal method for digital color images is proposed. In this method, differences of colors in an input color image are reflected effectively, and the perceived...     

Nano-structured surfaces on Ni–Ti generated by multiple shots of interfering femtosecond laser

Combined periodic structures composed of micron-sized periodic structure and nano-sized quasi periodic structure were generated on Ni–Ti target by multiple shots of interfering femtosecond laser beams. The micron-sized structure was generated by the interference pattern of four beams, and the nano-sized quasi period was generated due to the multiple shot effect of femtosecond laser. The structures were investigated in detail by two-dimensional fast Fourier transform (2D-FFT). The power spectra showed small spots and fuzzy spots due to precise period and quasi period, respectively. The most major size of the quasi periodic structure was 580 nm.     

Paraxial propagation in disclinated amorphous media

We study paraxial beam propagation along the wedge axis of a disclinated amorphous medium. The defect-induced inhomogeneity results in Berry phase and curvature that are affected by the induced uniaxial anisotropy. The Berry phase manifests itself as a precession of the polarization vector. The Berry curvature is responsible for the optical spin Hall effect in the disclinated medium, where beam deflection varies sinusoidally along the paraxial direction. Its application in determining the birefringence and the magnitude of the Frank vector is explained.     

Control of light pulse propagation with only a few cold atoms in a high-finesse microcavity

Propagation of a light pulse through a high-Q optical microcavity containing a few cold atoms (N<10) in its cavity mode is investigated experimentally. With less than ten cold rubidium atoms launched into an optical microcavity, up to 170 ns propagation lead time ("superluminal"), and 440 ns propagation delay time (subluminal) are observed. Comparison of the experimental data with numerical simulations as well as future experiments are discussed.     

Local chemical state change in Co–O resistance random access memory

Kelvin probe force microscopy (KFM) and conductive atomic force microscopy (C‐AFM) together with micro X‐ray photoelectron spectroscopy (XPS) were performed for the stacking structure comprising of the transition metal oxide Co–O and metal electrode, which exhibits large reproducible resistance switching. The application of the external voltage by the C‐AFM cantilever decreases the resistance of Co–O, which well accords with the non‐polar forming process observed in the Pt/Co–O/Pt trilayer, known as the candidate of resistance random access memory (ReRAM). Furthermore, the KFM and micro XPS experimentally revealed that the local reductive reaction of Co–O possibly nucleates the defect related energy levels which dominates the current conduction in the low resistance state. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

The behavior of a bubble between narrow parallel plates

Using the variational method, the behavior of a bubble situated between two parallel plates is theoretically analyzed, and the effect of solid walls on the bubble behavior is examined. As a result, it is clarified that when a spherical bubble is situated near to one side of two walls, its behavior is similar to the case of the bubble in the neighborhood of only one wall.

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Zusammenfassung Mit Benützung der Variationsrechnung wird das Verhalten einer Blase zwischen zwei parallelen ebenen Platten theoretisch gelöst. Der Einfluss der festen Grenzflächen auf das Verhalten der Blase wird untersucht. Es wurde gefunden, dass das Verhalten der kugelförmigen Blase in der Nähe der einen von beiden festen Grenzflächen ähnlich ist demjenigen in der Nähe einer festen Grenzfläche allein.