Hydrogen chemisorption on Si(111)√ 3×√ 3R30∘-B passivated surface studied by thermal desorption and scanning tunneling microscopy

Atomic H chemisorption on the Si(111)√ 3×√ 3R30^°-B surface has been studied by thermal desorption spectroscopy (TDS) and scanning tunneling microscopy (STM). The B-modified Si surface is known to be inert towards adsorbates, since the surface dangling bonds of Si adatoms are passivated by B atoms sitting in sub-surface sites. However, it was found that even on a perfectly passivated surface, H is adsorbed on the surface by destroying the original √ 3 × √ 3 structure. STM observations revealed that H exposure led to the creation of defects at surface sites, and H was subsequently adsorbed as Si-monohydride at these sites. H exposure also caused cluster island formation at the top surface. The islands are composed of hydrogenated amorphous Si atoms or B-hydrogen complexes.     

Effective cleavage of ditertiary glycols via vanadium(V)-catalyzed aerobic oxidation

The aerobic oxidation of ditertiary glycols catalyzed by oxytrichlorovanadium resulted in carbon-carbon bonds cleavage producing the ketones efficiently.     

Dielectric and piezoelectric properties of dense and porous PZT films prepared by sol-gel method

PZT films with different microstructure and Zr:Ti ratios were fabricated on ITO/glass and platinized silicon wafer substrates by dip-coating. A dense film of 2% porosity and a porous film of 19% porosity were obtained by repetition of thin and thick coatings, respectively. Development of pores during heating the film was examined and heating process factors were investigated. In the film fabricated on ITO/glass substrates, an existence of non-perovskite and low permittivity layer was confirmed by measurement of film thickness dependence of the dielectric constant. Among the films studied, the film with molar composition of Ti:Zr = 5:5 exhibited the largest dielectric constant and apparent piezoelectric coefficient, d ₃₃, though the values were small. Apparent piezoelectric coefficients of d ₃₃ and g ₃₃ of the porous films were larger than those of the dense films.     

Status of the electron accelerator for radioanalytical studies at tohoku university

We introduce the status of the 300 MeV electron linear accelerator used for radioanalytical studies at Tohoku University. In the accelerator facility, several scientific programs for producing radioactivity have been performed in several fields, such as photon-activation analysis, nuclear chemistry, hot-atom chemistry, and radioactive tracers for material science. First, we introduce an outline of the facility and the irradiation system for producing radioactivity. Then, several topics in these fields are explored in detail.     

Transition temperature to crystal phase of Al86Mn14 quasicrystal ultrafine particles determined by direct observation and characterization of surface oxide layer

Al–Mn quasicrystal ultrafine particles can be produced by the advanced gas evaporation method (AGEM), which is a method of preparing ultrafine alloy particles by coalescence growth among the particles near the evaporation sources. We investigated the phase transition temperature from a quasicrystal to a stable crystal, by examining successive electron diffraction patterns of an ultrafine particle in an in situ experiment using a transmission electron microscope. In spite of the report that the Al₈₆Mn₁₄ quasicrystal transforms into the crystal phase at around 400–670 °C on thin film specimens, the quasicrystal ultrafine particle transformed at 800 °C, i.e., the quasicrystal ultrafine particle is more stable. Since the cross-sectional view of the surface oxide layer of the quasicrystal ultrafine particles can be easily observed, the surface oxides of η-Al₂O₃ and MnO were characterized as a result of the oxidation of residual atoms on the surface of the produced alloy particles including the quasicrystals. The conditions required for Al–Mn quasicrystal ultrafine particle formation by the AGEM can be estimated under the cooling rate of 10⁵ K/s.     

Investigation of Fiber Design for Discrete Raman Amplifiers

A eff,R and gR of the optical fibers for discrete Raman amplifiers are theoretically and experimentally investigated.It is demonstrated that Gaussian approximation is adaptable for Aeff,R of these fibers, and gR does not depend on only core materials.     

A mild procedure for the oxidative cleavage of substituted indoles catalyzed by plant cell cultures

We have developed a novel procedure for the oxidative cleavage of indole carbon double bonds in the presence of H₂O₂ using plant cell cultures as a catalytic system. The oxidative procedure has some advantages, such as mild reactions, good yields, easy work-up and safety.     

Polymerization of bisdithiafulvenes with conjugated spacers using oxidative dimerization

Novel vinylogous tetrathiafulvalene (TTF) containing polymers ( 13 and 14 ) were prepared by the oxidative dimerization polymerization of bisdithiafulvenes. The obtained polymers were soluble in common organic solvents such as CHCl₃. The structures of the polymers were confirmed by ¹H NMR and cyclic voltammetry analysis. The number‐average molecular weights of 13 and 14 were estimated from gel permeation chromatography to be 3600 and 3800, respectively. Through the introduction of phenylene or phenylene–vinylene spacers, distortion between dialkoxybenzene and vinylogous TTF units was effectively prevented according to ultraviolet–visible analysis. The polymers exhibited a strong electron‐donating property investigated by cyclic voltammetry analysis. Chemical doping by CF₃SO₃H gave doped polymers having a cationic radical and a dication of a vinylogous TTF unit. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 2027–2033, 2006     

Development of a surface-reaction system in a nanoliter droplet made by an ink-jet microchip.

A surface-reaction system in a nanoliter water pool using an ink-jet microchip was developed. The reaction system in the nanodroplets formed on a poly(dimethylsiloxane) (PDMS) coated glass slide increased the diffusion-controlled reaction without using a nano-pump, specialized connector or highly sensitive detector. When nanoliter droplets were placed on the PDMS surface with a distance of 100 microm between them by the ink-jet microchip, the repeatabilities of the fluorescence intensity were 2.9% RSD (n = 7). The used ink-jet microchip had 4 different injection ports, and the distance between the ports was 0.995 mm. It was necessary to correct the distance in order to mix or dilute samples in a small droplet. The correction was successfully performed by moving the X-Y stage using inhouse-made software. A linear relationship was obtained between the Resorufin concentrations and the fluorescence intensity. We applied this system to an enzyme-linked immunosorbent assay (ELISA) for immunoglobulin A (IgA), and observed a difference in the fluorescence intensity derived from the amount of IgA (blank, 6.25 ng/mL, 12.5 ng/mL). These results show the usefulness of the open-type micro-analytical systems proposed by us.