Improvement of ozone yielding rate in atmospheric pressure barrierdischarges using a time-modulated power supply

The ozone (O₃) yielding rate of a high-pressure thin-gap barrier discharge was improved using a time-modulated power supply. The maximum improvement reached more than 20% compared with a continuous-wave power supply. The rate was strongly dependent on the discharge-off time, with the optimum one corresponding to the O₂ removal time from the discharge space. Dependence of the yielding rate on the off-time was numerically calculated using O and O₃ rate equations     

Probe Measurements of Wave Fluctuations Excited in Glow Discharges

Fluctuations of the electric field, the charged particle density; the electron temperature and the plasma potential are simultaneously measured by a probe in the positive column of helium glow discharge at a few torr gas pressure by exciting a small amplitude ionization wave. It is proposed that these values can be determined by analyzing the probe current.     

Oxidative transformation of tert-cyclobutanols by palladium catalysis under oxygen atmosphere

Palladium(II)-catalyzed oxidative reaction of tert-cyclobutanols involving the cleavage of a C-C bond via beta-carbon elimination under atmospheric pressure of oxygen is described. An alkylpalladium intermediate produced by beta-carbon elimination from a Pd(II) alcoholate gives a variety of products, depending on the substituents on the cyclobutane ring, in which reactions such as dehydrogenative ring opening, ring expansion and ring contraction are involved. For some substrates, the addition of a catalytic amount of ethyl acrylate dramatically accelerates the reaction. In all cases, the dehydrogenative products are obtained and the Pd(II)-hydride species produced at the final stage can be converted again to active Pd(II) species by molecular oxygen.     

Field-Like spin-transfer torque in a chiral helimagnet

Based on the microscopic model of sd coupling between free electrons and local moments, we present a quantum calculation of a nonadiabatic spin-transfer torque in a chiral helimagnet.     

Photochromism of a diarylethene having an azulene ring

Diarylethene derivatives incorporating an azulene ring at the ethene moiety were synthesized. One derivative having thiazole rings showed the expected coloration reaction by excitation at 313 nm (to a higher singlet state) but not when excited at 635 nm (S(0) to S(1) excitation). The system demonstrates that the cyclization reaction can be controlled by selective excitation at different wavelengths of the absorption spectrum. On the other hand, another derivative having thiophene rings did not show any photochromism. The results clearly show the importance of the coplanarity of the system for the photoisomerization.     

pH-Responsive Cy5 dyes having nucleophilic substituents for molecular imaging

pH-Responsive fluorescent pentamethine cyanine (Cy5) derivatives having nucleophilic substituents were synthesized. Cy5 derivatives 1-O having mercaptopropyl, hydroxypropyl, and aminopropyl groups on an indole nitrogen atom showed pH-dependent equilibria between a fluorescent open-ring structure (1-O) and a non-fluorescent closed-ring structure (1-C) in pH ranges 3–7, 6–7.5, and 8–9, respectively. pH-Responsive dyes 1a-C having a 1,3-thiazinane structure were easily internalized into A549 cells and converted to open-ring structure 1a-O in response to the relatively low pH of acidic compartments in the cells.     

Catalytic Diastereoselective Imidation of Diaryl Sulfides Bearing a Chiral Oxazolinyl Moiety with Chloramine T Trihydrate

Up to 99 % de is obtained in the imidation of diaryl sulfides bearing a chiral oxazolinyl moiety at the ortho position. The corresponding N-p-tosylsulfimides are produced upon use of chloramine T trihydrate in the presence of Cu(OTf)₂ as catalyst [Eq. (1)]. OTf=trifluoromethanesulfonate; Ts=toluenesulfonyl.