Pulsed EPR study on large dynamic electron polarisation created in the quenching of photo-excited xanthene dyes by nitroxide radicals in aqueous solutions

Dynamic electron polarisation (DEP) produced by the quenching of dye molecules in the triplet excited states by nitroxide radicals was investigated in aqueous solutions by pulsed electron paramagnetic resonance and transient absorption spectroscopy. An analysis of the measured quenching rate constants suggests that quenching is promoted by either exchange or charge-transfer mechanisms for a triplet dye and a doublet radical pair. An unusually large DEP on the radical was found generated in the nitroxide and Eosin Y or Rose Bengal systems in aqueous solutions. Quantitative analysis indicates that the DEP values in aqueous solutions range from ?40 to ?150 in the unit of thermal spin polarisation, which is in contrast to previously reported small DEP values of less than ?10 for organic triplet molecules in benzene solutions [22–27,29,31,32]. From the theoretical analysis of DEP, an origin of this large DEP was attributed to the notably slow diffusion motion of Eosin Y and Rose Bengal in water.     

Cinchona alkaloids are also produced by an endophytic filamentous fungus living in cinchona plant

We report that the endophytic filamentous fungus Diaporthe sp., isolated from Cinchona ledgeriana and cultivated in a synthetic liquid medium, produces Cinchona alkaloids (quinine, quinidine, cinchonidine, and cinchonine). This shows that Cinchona alkaloids are produced not only in Cinchona plant cells, but also in endophytic microbe cells.     

Quadrature phase-shifting interferometer using spatial carrier

We propose a high-speed phase measurement using a phase calculation algorithm in a quadrature phase-shifting interferometer (QPI), which is applied to tilted fringes. Although the spatial carrier method is useful for a high-speed measurement with a single imaging sensor, the spatial resolution in conventional phase calculation algorithms is reduced owing to the use of three or more phase-shifted data at different sample points. Phases in the QPI method can be calculated with only two quadarture phase-shifted data extracted from the tilted fringes before and after a phase change of the interferometer. Thus, the proposed method can suppress the reduction of the spatial resolution compared with that in conventional methods, and makes it possible to measure a phase at high-speed. The principle and experimental results of this technique are presented.     

Development of a highly selective fluorescence probe for hydrogen sulfide

Hydrogen sulfide (H(2)S) has recently been identified as a biological response modifier. Here, we report the design and synthesis of a novel fluorescence probe for H(2)S, HSip-1, utilizing azamacrocyclic copper(II) ion complex chemistry to control the fluorescence. HSip-1 showed high selectivity and high sensitivity for H(2)S, and its potential for biological applications was confirmed by employing it for fluorescence imaging of H(2)S in live cells.     

Highly efficient, organocatalytic aerobic alcohol oxidation

5-Fluoro-2-azaadamantane N-oxyl (5-F-AZADO) realizes a simple, organocatalytic aerobic alcohol oxidation system that has a wide scope under mild conditions at ambient pressure and temperature and is weakly acidic and halogen- and transition-metal-free. The oxoammonium nitrate (5-F-AZADO(+)NO(3)(-)) works as a bifunctional catalyst of 5-F-AZADO and NO(x) that enables the catalytic aerobic oxidation of alcohols by itself (a metal-salt-free system).     

Ionophoretic activities of oligopeptide lactones and resin-glycosides in human erythrocytes

Oligopeptide lactones (theonellapeptolides) isolated from the Okinawan marine sponge Theonella swinhoei and resin-glycosides (merremosides) from the tuber of an Indonesian medicinal plant Merremia mammosa were examined regarding their activities in transporting Na+, K+, and Ca++ ions into human erythrocytes. Each of these lactones, which had been shown, using a supported liquid membrane, to have an ionophoretic effect on the alkali metal ions, transported the ions to a different extent. The ion transporting activities of these compounds were completely lost when the macrocyclic lactone structures were cleaved by sodium methylate. Resin-glycosides with an additional branched glycosyl residue showed much greater ion transporting activities than those without it.     

An in situ transport measurement of interfaces between SrTiO3(1 0 0) surface and an amorphous wide-gap insulator

We have explored the transport properties of the interface between a SrTiO₃(1 0 0) single crystal and a CaHfO₃ wide-gap insulator layer deposited by pulsed laser deposition. The electrical transport measurements were done in situ during the heterojunction fabrication and consistently showed an enhancement of interface conductivity. A conducting interface was always obtained, independent of deposition parameters (laser pulse rate, laser fluence, oxygen pressure, and substrate termination). The conduction was attributed to plume-induced photocurrent in SrTiO₃. The current decay rate after insulator film fabrication was strongly influenced by substrate termination. An exponential relaxation-type photocurrent decay was clearly seen on SrO-termination, whereas a nearly constant conductivity was seen for up to 24 h on TiO₂-terminated surfaces.     

Synthesis and properties of new chiral dopants containing a δ-lactone ring for practical ferroelectric liquid crystal mixtures

A series of new optically active δ-lactones were synthesized as chiral dopants for ferroelectric liquid crystals (FLCs). The response time of an FLC mixture containing 4 mol% (S)-2,2-dimethyl-5-[2-fluoro-4-(5-n-octylpyrimidin-2-yl)-phenoxy[methyl-δ-valerolactone was 25 μs at 25°C. (0-90 per cent change in light transmission, 10 V μm^-1). The synthesis and properties of these materials as practical chiral dopants are reported.