Synthesis and properties of novel macrocyclic compounds bearing thiourea moieties by use of chemical feature of hypervalent sulfur

Macrocyclic compounds 5a‐i bearing two tetraazathiapentalene frameworks were synthesized by the reaction of 10‐S‐3 tetraazathiapentalene derivatives 3a‐f with compounds having various diisothiocyanate functions 4a‐e. The reduction of the macrocyclic compounds with NaBH₄ afforded the ring‐opened macrocyclic compounds 11a‐b and 11e‐h by elimination of the hypervalent sulfur. The structures of these compounds were established by their spectral data and also by the X‐ray crystallographic analysis of lla. The other ring‐opened macrocyclic compounds 14a and 14e‐h that bear four thiourea groups were synthesized by alkaline hydrolysis of 5a and 5e‐h in that elimination of the C=S^IV moiety in the tetraazathiapentalene rings occurred.     

Self-discharge characteristics of an electric double-layer capacitor with polymer hydrogel electrolyte

An electric double-layer capacitor (EDLC) was assembled with the polymer hydrogel electrolyte prepared from cross-linked potassium poly(acrylate) (PAAK) and KOH aqueous solution, and the self-discharge characteristics were investigated. The EDLC cell with the polymer hydrogel electrolyte showed lower voltage decay on open circuit than that with a KOH aqueous solution. Moreover, it was found that the leakage current of the EDLC cell was markedly suppressed by using the polymer hydrogel electrolyte. The suppression was enhanced with increasing PAAK content in the electrolyte. These results strongly suggest that the PAAK plays an important role in the suppression of self-discharge.     

Real-time optical measuring system for dye colour and concentration-II. Dispersive dye

A real-time measuring method of a dispersive dye, i.e. oil dye, has been developed which enables us to measure the concentration and its fluctuation of the three base colours. The method is based on the light scattering theory and its principle requires three different lasers having the three base colours. The system consisted of a semiconductor laser and argon ion laser for light sources, a photodiode for a light detector and a personal computer for data processing. Detection sensitivity for the dye concentration was about 1 mg/l and was applicable for practical use.     

Fluorescent polymer particles incorporating pyrene derivatives

Fluorescent polymer particles incorporating pyrene and alkynylpyrenes were prepared by miniemulsion polymerization of styrene. The pyrenes were simply dissolved in styrene monomer and then added to the reaction mixture in a vessel, followed by ultrasonication and the polymerization. The pyrenes were incorporated in the polystyrene particles and gave monomer fluorescence emission. The fluorescent particles incorporating the alkynylpyrenes, which have high fluorescence quantum yield and short fluorescence lifetime, showed the same fluorescence emission intensity under air and nitrogen. The fluorescence of the alkynylpyrenes in the polymer particles will not be quenched by molecular dioxygen in contrast to that in organic solvents. Incorporation of fluorophore into polymer particles will protect the fluorophore from its undesirable interaction with oxygen, affording the particles highly fluorescent even under air. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 1470–1475, 2008     

First observation of luminescence from tris(2,2'-bipyridine)ruthenium(II) triggered by anodic oxidation of oligodeoxyribonucleotide.

Anodic oxidation of oligodeoxyribonucleotide in an alkaline aqueous medium containing tris(2,2'-bipyridine)ruthenium(II) (Ru(bpy)3(2+)) was shown to cause luminescence around +1.3 V (vs. Ag/AgCl) with a maximal intensity at approximately 600 nm, possibly originating from Ru(bpy)3(2+) in the d-pi* triplet state. A pivotal initial stage in the light production path was postulated to be the anodic oxidation of 2-deoxyribose residue. This reaction seems to be available for the determination of sub-micromol dm(-3) levels of oligodeoxyribonucleotide.     

Measurement of the production rates of <Superscript>36</Superscript>Cl from Cl,K, and Ca in concrete at the 500 MeV neutron irradiation facility at KENS

In order to estimate the total radioactivity induced in a concrete shield by thermal neutron-capture reactions at high-energy accelerator facilities, the observed activity of ³⁶Cl in the concrete is expected to serve as an indicator of the thermal neutron fluence. Since ³⁶Cl can also be produced from K and Ca by spallation reactions, we measured these production rates in order to clarify the contribution of each reaction. The Cl, K, and Ca targets were irradiated with neutrons having a maximum energy of 500 MeV. As a result, the production rates of ³⁶Cl from Cl were only two orders higher than those from K and Ca. It was found that the ³⁶Cl production ratios from Cl, K, and Ca were 6.7%, 6.8%, and 86.5%, respectively, and Ca was the main source of ³⁶Cl production.     

Second variation and Legendrian stabilities of minimal Legendrian submanifolds in Sasakian manifolds

First, we derive a new second variation formula which holds for minimal Legendrian submanifolds in Sasakian manifolds. Using this, we prove that any minimal Legendrian submanifold in an η-Einstein Sasakian manifold with “nonpositive” η-Ricci constant is stable. Next we introduce the notion of the Legendrian stability of minimal Legendrian submanifolds in Sasakian manifolds. Using our second variation formula, we find a general criterion for the Legendrian stability of minimal Legendrian submanifolds in η-Einstein Sasakian manifolds with “positive” η-Ricci constant.