Fabrication of photonic crystals in ZnS-doped glass

Three-dimensional photonic crystals were fabricated in a ZnS-doped silicate glass by use of a femtosecond pulsed laser. Woodpile structures consisting of 36 layers were produced by focusing with a 100x (1.35-numerical-aperture) objective. Attenuations of approximately 3-8 dB arising from a photonic bandgap were observed in the visible and the near-infrared regions.     

Enhancement of efficiency in photo-excitation to the triplet state by laser-pulse reshaping

An optical system is proposed to enhance efficiency in photo-excitation to the triplet state by reshaping an original laser pulse into a train of pulses. This optical system can be used to improve the attainable nuclear spin polarization in dynamic nuclear polarization experiments using photo-excited triplet electron spins.     

The interaction of an anionic gemini surfactant with conventional anionic surfactants

The interaction in two mixtures of an anionic gemini surfactant having N ,N -dialkylamide and carboxylate groups in a molecule, (CH2)2[N(COC11H23)CH(CO2H)CH2(CO2H)]2. 2NaOH (GA), and conventional anionic surfactants have been investigated in 0.1 M NaCl at pH 5.0. The two mixtures are GA/sodium dodecylsulfate (SDS) and GA/sodium N -dodecanoylglutamate (AGS) at a molar fraction of GA, alphaGA = 0.25 . Mixtures of both GA/SDS and GA/AGS exhibit synergism in surface tension reduction effectiveness. The GA/SDS mixture also exhibits synergism in surface tension reduction efficiency and mixed micelle formation, whereas the GA/AGS mixture does not. The interaction in mixed adsorption film formation is stronger than that in mixed micelle formation for the two mixtures. The interaction in the formation of the mixed adsorption film and the mixed micelle for the GA/SDS mixture is stronger in both formations than that for the GA/AGS mixture. The stronger interaction for the GA/SDS mixture may be caused by the combination of the smaller minimum area per molecule at the air/water interface (Amin) of the head groups in the GA molecule and the larger Amin in the SDS molecule.     

Reductive cleavage of the C-O bond of acetals and orthoesters: reduction by silane in the presence of a Rh-PPh3 complex

Reductions of acetals to ethers and of orthoester to acetal by hydrosilane using rhodium catalyst are described.     

A recursive algorithm for finding the minimum norm point in a polytope and a pair of closest points in two polytopes

For a given pair of finite point setsP andQ in some Euclidean space we consider two problems: Problem 1 of finding the minimum Euclidean norm point in the convex hull ofP and Problem 2 of finding a minimum Euclidean distance pair of points in the convex hulls ofP andQ. We propose a finite recursive algorithm for these problems. The algorithm is not based on the simplicial decomposition of convex sets and does not require to solve systems of linear equations.     

On the dibaryon ansatz in nonlinear sigma models: Review,developments and problems

I present a short review, focussing on five points of view, of the dibaryon ansatz, which plays an important role in the study of nonlinear sigma models, and propose new problems concerning this ansatz.Partially supported by the Grant-in-Aid for Scientific Research No. 61460005.     

Phase-transfer-catalyzed asymmetric Darzens reaction using a new chiral ammonium salt

Catalytic asymmetric Darzens reaction of haloamides is described. A new and easily-prepared bis-ammonium salt derived from BINOL acts as an effective phase-transfer catalyst and efficiently promotes the reaction to give the desired epoxides under quite mild conditions with up to 70% ee.