Multiple nuclear Bragg scattering

Multiple nuclear resonant scattering from an ⁵⁷FeBO₃ single crystal has been observed in the three-beam case. A change of the lifetime and a modulation of the quantum beat were observed in our study. The high brilliance of synchrotron radiation and the high perfection of the synthetic ⁵⁷FeBO₃ single crystal enabled us to observe such an effect. This revised version was published online in August 2006 with corrections to the Cover Date.     

Oxidation of Benzyl Alcohol with CuII and ZnII Complexes of the Phenoxyl Radical as a Model of the Reaction of Galactose Oxidase

Profound insights into the catalytic mechanism of galactose oxidase (GO) are offered by new models of the active form of the metalloenzyme. The important role of the Cu^II center in the oxidation of benzyl alcohol to benzaldehyde by the Cu^II–phenoxyl radical complex of ligand 1 has been revealed by comparison with the reactivity of the corresponding Zn^II–phenoxyl radical complex; py=2-pyridyl.     

Synthetic studies on quassinoids: a stereoselective construction of the picrasane skeleton

12β-Hydroxypicrasan-3-one, a compound having the correct relative stereochemistry of all the six ring-juncture chiral centers of the picrasane skeleton, was synthesized from a known tricyclic compound, using the orthoester Claisen rearrangement and lead tetraacetate oxidation as key reactions.     

Enhancement of the electrocatalytic O2 reduction on Pt–Fe alloys

The design of high performance cathode electrocatalysts is essential for polymer–electrolyte fuel cells, which are now attracting enormous interest as a primary power source for zero-emission electric vehicles. We have discovered a significant enhancement of electrocatalytic activity of Pt by alloying with Fe, and found a maximum activity at ca. 50% Fe content, which results in 25 times higher activity than pure Pt activity. It was confirmed experimentally at Pt–Fe bulk alloys that the alloy catalyst surface consists of a pure Pt skin-layer (<1 nm in thickness) that is modified in the electronic structure by that of the bulk alloy. The enhancement could be well explained by the 5d-vacancy of the surface, but not by Pt interatomic distance or roughening of the surfaces.     

Near-Infrared Imaging Using a High-Speed Monitoring Near Infrared Hyperspectral Camera(Compovision)

This review paper reports near-infrared (NIR) imaging studies using a newly-developed NIR camera, Compovision. Compovision can measure a significantly wide area of 150 mm×250 mm at high speed of between 2 and 5 s. It enables a wide spectral region measurement in the 1 000～2 350 nm range at 6 nm intervals. We investigated the potential of Compovision in the applications to industrial problems such as the evaluation of pharmaceutical tablets and polymers. Our studies have demonstrated that NIR imaging based on Compovision can solve several issues such as long acquisition times and relatively low sensitivity of detection. NIR imaging with Compovision is strongly expected to be applied not only to pharmaceutical tablet monitoring and polymer characterization but also to various applications such as those to food products, biomedical substances and organic and inorganic materials.     

Chemical synthesis of homogeneous human glycosyl-interferon-β that exhibits potent antitumor activity in vivo

Chemical synthesis of homogeneous human glycoproteins exhibiting bioactivity in vivo has been a challenging task. In an effort to overcome this long-standing problem, we selected interferon-β and examined its synthesis. The 166 residue polypeptide chain of interferon-β was prepared by covalent condensation of two synthetic peptide segments and a glycosylated synthetic peptide bearing a complex-type glycan of biological origin. The peptides were covalently condensed by native chemical ligation. Selective desulfurization followed by deprotection of the two Cys(Acm) residues gave the target full-length polypeptide chain of interferon-β bearing either a complex-type sialyl biantennary oligosaccharide or its asialo form. Subsequent folding with concomitant formation of the native disulfide bond afforded correctly folded homogeneous glycosyl-interferon-β. The chemically synthesized sialyl interferon-β exhibited potent antitumor activity in vivo.