Masataka Ohoka

High Throughput Cell Electroporation Array Fabricated by Single-Mask Inclined UV Lithography Exposure and Oxygen Plasma Etching

In this paper, we propose a multiple cell treatment array with high-density arrayed micro-orifice having an individually accessible microchannel and electrodes. More than 10000 micro-orifices with the diameter of 2 mum can be simultaneously fabricated by Single-Mask inclined UV photolithography for embedded network (SIMPLE) process with the oxygen plasma etching. More than 200 living cells immobilized at the arrayed micro-orifices were permeabilized by electroporation and allowed to uptake an foreign impermeant substance.

Stabilization of photoejected electrons produced through two-photon ionization of dopant chromophores in electron-accepting polyester film

Abstract Anionic as well as cationic species formed through two-photon ionization of dopant chromophores in a copolymer (polyester) film having two weak electron-accepting groups, terephthaloyl and isophthaloyl groups, were simultaneously observed at 20 K by absorption measurement. It is found that most of the photoejected electrons migrate and are localized at higher electron-accepting terephthaloyl groups in the main chain of the polyester. The decay of both ionic species thus formed in the polyester film at low temperatures mainly results from charge recombination.

Radiation-induced reactions of syndiotactic polypropylene

SummaryThe radiation-induced reaction of highly syndiotactic polypropylene was examined by following the changes in limiting viscosity, molecular weight distribution, and stereoregularity. The degree of syndiotacticity clearly decreased even when there was no apparent change in molecular weight. Irradiation at an elevated temperature caused a marked decrease in molecular weight and formation of unsaturated residues.

Inherent phase transition and polymerization mechanism in irradiated diacetylene crystal : 1,6-(N-carbazolyl)-2,4-hexadiyne (DCH)

Abstract The crystal of 1,6-di(N-carbazolyl)-2,4-hexadiyne undergoes an inherent phase transition (IPT). In the present work with differential scanning calorimetry (DSC), it has been determined that the temperature and the heat of IPT are 148K and 1.2kcal/mol in as-grown crystals, respectively. When the crystals have been irradiated at room temperature, the original endotherm signal has been shifted to the temperature side lower than 148K with decreasing its intensity. Similar changes have been observed by γ-irradiation at 77K and subsequent pulse-annealing. The decrease in signal intensity is interpreted in terms of the excess strain energy which is released at IPT by the polymers present in the crystal. The temperature shift of IPT is discussed with the concept of strain field induced by the formation of polymer.

[2 + 2]-Photocycloaddition of N-vinylcarbazole to dimethyl fumarate

The [2 + 2]-photocycloaddition of photoexcited N-vinylcarbazole (VCZ) with dimethyl fumarate (F) in nonpolar benzene solvent yields an oxetane. This oxetane is subsequently cleaved to give two methoxydiene isomer products. The existence of the exciplex emission, the effect of solvent polarity on the photoproducts, and triplet sensitizer and quencher experiments prove the existence of a singlet exciplex intermediate in the photocycloaddition of VCZ and F.

Thermal study on polymerization through phase transition in carbazolyl substituted diacetylenes

Abstract The asymmetric monomers of 1-( N -carbazolyl)-6-(4′-methyl terephthaloyl-2,4-hexadiyne and 1-( N -carbazolyl)-6-(2′,4′-dinitrophenyl ether)-2,4-hexadiyne were synthesized. Their crystal structures have been determined with x-ray diffraction analysis. The present crystals have showed neither topochemical polymerization nor phase transition. The non-polymerizability of the crystals is discussed with monomer packing parameters and is consistent with the Baughmans model.