Probing interaction of paramagnetic electron with conduction electrons in high Tc superconductor LaSrCuO by (μ-O) spin relaxation

The paramagnetic (μ^-O) state formed at the oxygen site in high T_c LaSrCuO was used to probe an interaction between the localized moment of the paramagnetic electron and the conduction electrons via zero field μ^- spin relaxation. The enhanced relaxation rates consistently observed in the superconducting state of various Sr concentrations are explained as an effect of spin‐pairing in the high T_c supercurrent. This revised version was published online in August 2006 with corrections to the Cover Date.     

Signal enhancement in ESR spin-trapping for hydroxyl radicals.

In an ESR spin-trapping measurement of hydroxyl radicals formed in a Fenton reaction, the trapping efficiency with DMPO increased by about 300 times in a sodium trifluoroacetate solution, whereas it was little changed in a phosphate buffer.     

Stability of small fullerenes C n (n=36,40 and 60): A topological and molecular orbital approach

Summary By semi-empirical molecular orbital calculations stability of fullerenes was analyzed in terms of topological parameters, such as the number of special fragments and the number of three types of abutting bonds between two 5-membered rings. Relative stability was compared by AM1 method for all spectrally distinct closed-shell isomers of C₃₆ and C₄₀ fullerenes, and for some closed-shell isomers of C₆₀ fullerene. Molecular geometries of these fullerenes were also optimized. Their relative stabilities were well explained by the instability of abutting bonds.     

Effects of fullerene encapsulation on structure and photophysical properties of porphyrin-linked single-walled carbon nanotubes

Fullerene-encapsulating single-walled carbon nanotubes (C(60)@SWNT) linked with porphyrins by a short bridge have been prepared for the first time. Steady state and time-resolved spectroscopies demonstrated the initial formation of an exciplex state, followed by a charge-separated state.     

Incorporation of organometallic Ru complexes into apo-ferritin cage

Spherical protein cages such as an iron storage protein, ferritin, have great potential as nanometer-scale capsules to assemble and store metal ions and complexes. We report herein the synthesis of a composite of an apo-ferritin cage and Ru(p-cymene) complexes. Ru complexes were efficiently incorporated into the ferritin cavity without degradation of its cage structure. X-Ray crystallography revealed that the Ru complexes were immobilized on the interior surface of the cage mainly by the coordination of histidine residues.     

Photoinduced Reversible Topographical Changes on Diarylethene Microcrystalline Surfaces with Biomimetic Wetting Properties

Reversible topographical changes were observed on a photochromic diarylethene microcrystalline film surface by alternate irradiation with UV and visible light. Two types of surfaces were prepared from this film: 1) Storage of the film at 30 °C for 24 hours in the dark after UV irradiation afforded a surface that was covered with needle‐shaped crystals, whose diameter and length were approximately 1 μm and 10 μm, respectively, and showed a superhydrophobic lotus effect. 2) Storage of the film at 70 °C for 3 hours in the dark caused the needle‐shaped crystals to be converted into larger rod‐like crystals (5∼8 μm wide and 20∼30 μm long) by Ostwald ripening and a disappearance of the lotus effect. The obtained activation energy of the formation of the needle‐ and rod‐shaped crystals was 143 and 162 kJ mol⁻¹, respectively. Subsequent UV irradiation to the surface, which was followed by storage at 50 °C for 1 hour in the dark, gave a doubly rough structure; small needle‐shaped crystals were formed between the larger rod‐shaped crystals. The surface showed both superhydrophobic properties and the pinned effect of the water droplet: the petal effect. Fractal analysis of both surfaces were carried out using a box‐counting method, and the lotus effect was observed in the presence of smaller‐sized crystals, whilst the petal effect was observed with larger sized crystals (ca. 100 μm). We demonstrated that the hydrophobic property was controlled by the distribution in crystal size of the closed‐ring isomer of the diarylethene. Visible‐light irradiation of both rough surfaces afforded surfaces with cubic‐shaped micro‐crystals of the open‐ring isomer.     

A rapid gel electrophoretic chip for serum cholesterol determination

We present a rapid gel electrophoretic chip, composed of 2.5% (w/v) acrylamide and 1% (w/v) agarose gel, for serum cholesterol determination using a photo lithography technique. After optimizations, we determined the lipoprotein concentration of standard serum using a conventional enzyme method. The serum was diluted, stained and loaded for 15 min onto the chip. After loading, the intensities of low density lipoprotein cholesterol (LDL-C) and high density lipoprotein cholesterol (HDL-C) bands separated at the chip were estimated using an image analyzer. The intensities of these bands corresponded to concentrations obtained from a standard enzyme-based method. The detected LDL-C and HDL-C concentrations were linear up to 146 mg dL(-1) and 53 mg dL(-1) respectively. Finally, we carried out the cholesterol analysis using real biological samples obtained from nine volunteers using our electrophoretic chip. The LDL-C and HDL-C levels detected using our chip correlated well with the results obtained using the conventional enzyme-based method r(2) = 0.98 and r(2) = 0.86 for LDL-C and HDL-C, respectively. Although our sample size is small and confined only to health volunteers, we have demonstrated that this proof-of-concept gel electrophoretic chip can determine lipoproteins, simultaneously.