Self-crosslinkable polymers. I. Copolymerization of glycidyl methacrylate with 2-vinylpyridine and 2-vinyl-5-ethylpyridine

A soluble and self-crosslinkable linear copolymer with pendant epoxy and pyridyl groups was obtained from glycidyl methacrylate (M₁) and 2-vinylpyridine (M₂) or 2-vinyl-5-ethylpyridine (M₂) by the action of azobisisobutyronitrile. The monomer reactivity ratios were determined in tetrahydrofuran at 60°C: r₁ = 0.510, r₂ = 0.620 with 2-vinylpyridine and r₁ = 0.57, r₂ = 0.62 with 2-vinyl-5-ethylpyridine. These were consistent with the calculated values with the reported Q and e values for these monomers. The intrinsic viscosities of the copolymers with 2-vinylpyridine and with 2-vinyl-5-ethylpyridine were found to be 0.17–0.19 and 0.26–0.38, respectively, in tetrahydrofuran at 30°C; they were independent of the copolymer composition. The copolymers were amorphous, had no clear melting points, and became insoluble crosslinked polymers under heating without further addition of any curing agents.     

Ruthenium-catalyzed arylation of 2-alkenylpyridines with aryl bromides: alternative E,Z-selectivity to Mizoroki-Heck reaction

Regio- and stereoselective arylation of 2-alkenylpyridines with aryl bromides is catalyzed by specific Ru(II)-phosphine complexes affording beta-arylated (Z)-2-alkenylpyridines, in which the aryl moiety is introduced cis to the pyridyl group. This geometrical selectivity is in sharp contrast to the Mizoroki-Heck reaction. [reaction: see text]     

Thermal decompositions of formates. Part VI. Thermal dehydration reaction of copper(II) formate dihydrate

The thermal dehydration reactions of two kinds of copper(II) formate dihydrate, which differ in origin and preparation history, have been investigated by means of TG, DTA and DSC. The kinetics of isothermal dehydration were studied by weight loss, and the difference in kinetic behavior between these two samples was related to the difference in origin and preparation history. On the whole, the dehydration mechanisms of these two samples were found to be phase boundary controlled contracting interface reactions.     

Thermal decomposition of formates. Part VIII. Thermal dehydration of Dy(III), Ho(III), Er(III), Tm(III), Yb(III) and Lu(III) formate dihydrates

The thermal dehydration of some rare earth metal formate dihydrates were studied by means of thermogravimetry, differential thermal analysis and differential scanning calorimetry.The dehydration took place successively as a one step reaction for all of the formate dihydrates examined. The reaction order of dehydration was found to be $\text{2}\text{3}$ for all of the salts examined, which indicated that the rate of dehydration was controlled by a chemical process at a phase boundary.The values of the activation energy, frequency factor and the enthalpy change of dehydration for all of the dihydrates were 108–142 kJ mole^?1, 10¹⁶–10¹⁷ min^?1 and 109–147 kJ mole^?1, respectively.Both the temperature at which the dehydration occurred and the enthalpy change increased as the reciprocal of the radius of the metallic ion increased.     

The system BaOGeO2 at high pressures and temperatures,with special reference to high-pressure transformations in BaGeO3, BaGe2O5, and Ba2Ge5O12

Phase relations in the system BaOGeO₂ were investigated in the pressure range 20–70 kbar in the temperature range 750–1200°C. Several new phases were identified in this system: an atmospheric phase of BaGe₂O₅ (monoclinic BaGe₂O₅ I), two high-pressure phases of BaGe₂O₅ (monoclinic BaGe₂O₅ II and tetragonal BaGe₂O₅ III), and a high-pressure phase of Ba₂Ge₅O₁₂. The phase boundary curve between BaGe₂O₅ II and BaGe₂O₅ III was preliminarily determined as P(kbar) = 7.7 + 0.047T (°C). The high-pressure phases of BaGeO₃, which were previously reported by Y. Shimizu, Y. Syono, and S. Akimoto (High Temp.-High Pressures2, 113 (1970)) in the pressure range 15–95 kbar, were interpreted to be not single-phase materials but complicated mixtures of more than two phases in the system BaOGeO₂. X-Ray powder diffraction data for the new compounds synthesized in this study are given.     

Direct micropatterning of high dielectric BaTiO3 films by laser-induced pyrolysis with a nano-crystalline seeding technique

A direct patterning method of dielectric BaTiO₃ (BT) films is proposed, which applies laser-induced pyrolysis in combination with nano-crystalline seeding technique. A precursor solution of a BT complex alkoxide containing BT nano-crystalline particles with polyvinylpyrollidone (PVP) as dispersion stabilizer was spin-coated on Pt substrate. An Ar⁺ laser beam was focused and scanned on spin-coated BT films, which induced pyrolysis and crystallization of the films with spatial selectivity. Micropatterns were obtained by striping laser-unirradiated regions on the films with HCl aqueous solution. Raman spectra of the micropattern confirmed that the structures were tetragonal crystalline BT. Clear micropatterns with a line width of ca. 3 μm and an interval of 5 μm were formed at PVP concentrations of 25 and 50 kg/m³. The dielectric constant and dissipation factor of the film fabricated at a laser energy density of 27 MW/cm² and a scanning speed of 25 μm/s attained 76.2 and 0.07, respectively, for a measurement frequency of 100 kHz.     

A video camera system for coaxial observation of a sample with an incident soft X‐ray beam

A video camera system for observing a sample from the direction of an incident soft X‐ray beam has been developed. The sample is seen via two reflecting mirrors. The first mirror, which has a hole to allow the soft X‐ray beam to pass through, is set on the beam axis in a vacuum. The second mirror is used to cancel out the mirror inversion of the image. This camera system is used for efficient positioning of samples in a soft X‐ray beam.     

Effects of hydroxyls on the structural and room temperature ferromagnetic properties of Co doped SnO2 nanoparticles

Co doped SnO₂ nanoparticles have been prepared via a wet chemical method with different precipitation processes. The structure and morphology of Co doped SnO₂ nanoparticles demonstrate that the nanoparticles are in a rutile single phase and uniform, respectively. X-ray photoelectron spectroscopy shows that the Co dopants are in 2+ oxidation valence state and doped ∼2 atm% in SnO₂ nanoparticles. Moreover, Raman spectroscopy further confirms that Co doped SnO₂ nanoparticles have single phase crystallinity without forming any extra modes related to secondary phases. The magnetic measurements reveal that all nanoparticles exhibit room temperature ferromagnetism (RTFM) due to the presence of disorders and defects introduced by hydroxyls in the crystal structure. In addition, it has been clearly observed that the saturated magnetic moments are strongly affected by the precipitation processes which control the incorporation of hydroxyls into the lattice.     

High-performance optics for thermal microscopy

We have developed a thermal microscope which has an InSb detector and optics optimized for the camera. Using this system, we evaluated maximum resolution of a 30×/numerical aperture 0.71 lens made of silicon and germanium, and achieved the cutoff frequency of around 300 line pairs/mm, which is almost a diffraction-limited performance. The thermal microscope is installed on the THEMOS-1000, a product of Hamamatsu Photonics, for thermal emission analysis.