Synthesis and photochemical properties of novel multifunctional photopolymers with both pendant epoxy groups and phenacyl ester groups

Novel multifunctional photopolymers with both pendant epoxy groups and phenacyl ester groups were synthesized by the one‐pot method for the reaction of poly(methacrylic acid) with epibromohydrin; this was followed by a reaction with phenacylbromide with 1,8‐diazabicyclo‐[5.4.0]undecene‐7 as a condensation reagent. These esterification reactions proceeded smoothly and quantitatively under mild conditions. Moreover, the photochemical reactions of the resulting polymers were evaluated by UV and IR spectroscopy. The pendant phenacyl ester groups were photocleaved to give corresponding carboxyl groups, and then the produced carboxyl groups reacted with pendant epoxy groups. Furthermore, the baking process promoted a crosslinking reaction because of the addition reaction of epoxy groups with carboxyl groups after irradiation. It was also proven that the photochemical reactivity of the resulting polymers was affected by the structure of the phenacyl ester group. © 2001 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 39: 530–538, 2001     

Conjugates of a Dinuclear Zinc(II) Complex and DNA Oligomers as Novel Sequence-Selective Artificial Ribonucleases

Even in the presence of a large excess of Zn ^II ions , sequence-selective RNA hydrolysis is achieved by DNA conjugates involving a dinuclear Zn^II complex (shown schematically). This is because the cooperation of two Zn^II ions is essential for the RNA scission.     

The Poisson kernel for certain degenerate elliptic operators

Let $\text{L =}\text{1}\text{2}\text{∑}{}_{\mathrm{k\; =\; 1}}{}^{\mathrm{d}}\text{V}{}_{\mathrm{k}}{}^2\text{+ V}{}_0$ be a smooth second order differential operator on $\text{R}$ⁿ written in Hörmander form, and $\text{G}$ be a bounded open set with smooth noncharacteristic boundary. Under a global condition that ensures that the Dirichlet problem is well posed for L on $\text{G}$ and a nondegeneracy condition at the boundary (precisely: the Lie algebra generated by the vector fields V₀, V₁,…, V_d is of full rank on the boundary) then the harmonic measure for L starting at any point in $\text{G}$ has a smooth density with respect to the natural boundary measure. Estimates on the derivatives of this density (the Poisson kernel) similar to the classical estimates for the Poisson kernel for the Laplacian on a half space are given.     

Rotational vibration of poly(tetrafluoroethylene) chains by the electron spin resonance method

Temperature‐dependent electron spin resonance spectra of main‐chain free radicals, ? CF₂(β)? C · F(α)? CF₂(β)? , in poly(tetrafluoroethylene) (PTFE) were analyzed by the change in the hyperfine splitting due to β‐fluorines, which was a decreasing function of the observation temperature. The results were interpreted in terms of the rotational vibration around the C_α? C_β bond. The amplitude of the vibration was estimated on the assumption of its harmonic oscillation. The vibration of the PTFE chain was found to have a large amplitude in comparison with that of a polyethylene chain in single crystals. The vibration of the large amplitude was caused by a weak interchain interaction in the PTFE matrices. The amplitude of the vibration in crosslinked PTFE was much larger than that in noncrosslinked PTFE. This result indicated that the free radicals in crosslinked PTFE were trapped in the amorphous region, which had the disordered sites of crosslinking, whereas the free radicals in noncrosslinked PTFE were mainly trapped in the paracrystalline region. The decay reaction of the free radicals in the PTFE matrices was also related to the heterogeneity in the structure and the rotational vibration. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 1539–1547, 2004     

Stable profit sharing in a patent licensing game: general bargaining outcomes

By considering coalition structures formed by an external licensor of a patented technology and oligopolistic firms, we investigate licensing agreements that can be reached as bargaining outcomes under those coalition structures. The following results hold in a generalized patent licensing game. The core for a coalition structure is always empty, unless the grand coalition forms. We give a necessary and sufficient condition for the nonemptiness of the core (for the grand coalition). If the number of licensees that maximizes licensees’ total surplus is greater than the number of existing non-licensees, each symmetric bargaining set for a coalition structure is a singleton, and the optimal number of licensees that maximizes the licensor’s revenue is uniquely determined. The authors wish to thank the chief editor, anonymous referees, and participants in the 10th DC (Japan), the 3rd ICMA, and the 17th Stony Brook conference for helpful comments and suggestions. Thanks are extended to Ryo Kawasaki for editing English. They are partially supported by the MEXT Grant-in-Aid for 21 Century COE Program, Grant-in-Aid 18730517 (Watanabe), and Grant-in-Aid 16310107 (Muto).     

Compact and monolithic coarse wavelength-division multiplexer-demultiplexer fabricated by use of a high-spatial-frequency transmission grating buried in a slab waveguide

A compact and monolithic four-channel demultiplexer with 20-nm spacing was fabricated by use of a high-spatial-frequency transmission grating buried in a silica waveguide. The grating was successfully buried in a silica slab waveguide by overcladding by plasma-enhanced chemical-vapor deposition. The device's size was approximately 5.1 mm x 9.2 mm. The average insertion loss was 13 dB. The average cross talk was -15 dB for adjacent channels and -19 dB for nonadjacent channels. The polarization-dependent loss was estimated to be as low as 0.7 dB.     

High-pressure Raman study of Ba doped silicon clathrate

Vibrational properties of Ba doped Si clathrate are investigated at high pressures up to 20 GPa by Raman spectroscopy. Vibrations related with Ba encaged in the Si cages are observed below 100 cm(-1) by low-frequency Raman measurements of Ba8Si46 and Ba6.6Si46 clathrates. The high-pressure Raman spectra obtained for both compression and decompression processes reveal a new phase transition at 7 GPa, and the reversibility of the phase transition at 15 GPa. We investigate the mechanisms of these phase transitions, the interaction between the guest and host frame, and the volume dependence of the vibrational modes.