Application of photopolymer to core‐hair type microgels with various hair length

The new microgels, called “core‐hair” type microgels, were synthesized. They have a hair moiety consisting of the oxyhexano‐1,7‐diyl (? O? (CH₂)₅? C(O)? ) group as a spacer and the acryloyl group for polymerization. The hair length depends on the number of spacer units, and affects the viscosity and the thixotropy index of the microgel. These core‐hair microgels show the pseudo‐plastic flow of a non‐Newtonian fluid with moderate to high dispersibility in water or alcoholic solvents. Due ­to their viscosities and dispersibilities, these core‐hair microgels are useful for photopolymer, e.g. for screen printing. Therefore, these microgels were actually applied to screen printing and confirmed pattern forming on a screen printing plate through water development. We now discuss the relation between the viscosity, the dispersibility, the photosensitivity, and the rate of photopolymerization to the hair length of the microgel. Copyright © 2001 John Wiley & Sons, Ltd.     

Photo‐alignment material with azobenzene‐functionalized polymer linked in film

Application of a new azo‐polymer as a photo‐alignment material for liquid crystals (LCs) was demonstrated. 4‐(Vinyloxyethyloxy)azobenzene (VAZO), which has thermally reactive vinyl ether groups, reacted with the ? OH groups of poly(4‐hydroxystyrene) (PHS) during the baking process. The azo‐attached polymer (PHS‐VAZO) film showed anisotropic spectra after exposure to 365‐nm linear polarized light (LPL) unlike the VAZO‐doped poly(methylmethacrylate) (PMMA) film. The anisotropy of the film was small at high concentration of the azo‐chromophore because of thermal randomization of the polarized state. In the evaluation of photo‐alignment of the LC, the LC hybrid cell using the PHS‐VAZO film achieved high LC alignment. The azo‐attached polymer using the thermal reaction of vinyl ethers is useful for a photo‐alignment material. Copyright © 2002 John Wiley & Sons, Ltd.     

Sensitized red luminescence from Ce, Mn-doped glaserite-type alkaline-earth silicates

Bright red luminescence is observed from Ce, Mn-doped glaserite-type alkaline-earth silicates with M₂BaMgSi₂O₈ (M: Ba, Sr, Ca) chemical composition. Under UV excitation, Ce-doped M₂BaMgSi₂O₈ exhibits strong near-UV emission with asymmetric peak shape. UV-excited Mn-doped M₂BaMgSi₂O₈ compounds show visible red emission only when Ce³⁺ ions are doped together. These results indicate that Mn²⁺-derived red emission is caused by an efficient energy transfer from Ce³⁺ to Mn²⁺. The red emission becomes intense with an increase in Ba-amount. This trend originates from the relaxation of the selection rule for 3d-3d transition in Mn²⁺ ions, which is caused by the structural deformation due to Ba²⁺ occupation for layer-pockets.     

Interpolation Method for Computer-Generated Holograms Using Random Phase Technique

An interpolation method for reconstructed images of computer-generated holograms (CGHs) enables one to synthesize CGHs with a large space bandwidth product (SBWP) from CGHs with a small SBWP. The phase information of objects is regarded as constant because the method is based on digital image processing techniques. Therefore, diffraction efficiency is low due to the saturation effect in the recording process. To improve the diffraction efficiency, a random phase technique is employed for the interpolation method to the CGH. Effects of the random phase in the reconstructed image are discussed in several interpolation types. The interpolation method is also applied to a kinoform. Some computer simulations and optical experiments are presented.     

Vis‐sensitive photopolymer containing vinyl ether compound and pyrromethene dye

A visible light(vis)‐sensitive photoresist based on the concept of chemical amplification was developed utilizing poly(p‐hydroxystyrene) (PHS), 2,2‐bis[4‐(2‐(vinyloxy)‐ethoxy)phenyl]propane (BPA‐DEVE) as a crosslinking agent, N‐trifluoromethylsulfonyloxy‐1,8‐naphthalimide (NIT) as a photoacid generator (PAG) and pyrromethene dyes such as 1,3,5,7,9‐pentamethylbipyrromethene difluoroborate (PRH) and 2,8‐diethyl‐1,3,5,7,9‐pentamethylbipyrromethene difluoroborate (PRE) and 3,3′‐carbonylbis(7,7′‐diethylaminocoumarin) (KCD). On irradiation with an argon ion laser, the photopolymer comprising PRH and PRE exhibited a high sensitivity of 65 and 46 mJ cm^?2, respectively. It is suggested that the sensitization mechanism of the pyrromethene dye/PAG system involves singlet electron transfer. The sensitivity of the photoresist increased with the decreasing molecular weight of PHS because of the high dissolution rate. Copyright © 2002 John Wiley & Sons, Ltd.     

Concepts for a new class of all-polymer micropumps

This paper presents a polymer-based micropump addressing the cost, performance, and system compatibility issues that have limited the integration of on-chip micropumps into microanalysis systems. This pump uses dielectric elastomer actuation to periodically displace fluid, and a pair of elastomeric check valves to rectify the fluid's resulting movement. Its significant features include the use of a transparent substrate, self-priming capability, insensitivity to gas bubbles, and the ability to admit particles. A pump occupying less than 10 mm2 of chip space produced a 77 microl min(-1) flow rate. The pump has a high thermodynamic efficiency and exhibits little performance degradation over 10 hours of operation. In addition to its notable performance, the pump can be fabricated at low cost and directly integrated into microfluidic chips that use planar softlithography-formed structures. The new pump concept, fabrication, and experimental performance are discussed herein.     

Simultaneous spectrophotometric determination of phosphate and silicate ions in river water by using ion-exclusion chromatographic separation and post-column derivatization

The simultaneous spectrophotometric determination of phosphate and silicate ions in river water was examined by using ion-exclusion chromatography and post-column derivatization. Phosphate and silicate ions were separated by the ion-exclusion column packed with a polymethacrylate-based weakly acidic cation-exchange resin in the H⁺-form (TSKgel Super IC-A/C) by using ultra pure water as an eluent. After the post-column derivatization with molybdate and ascorbic acid, so-called molybdenum-blue, both ions were determined simultaneously by spectrophotometry. The effects of sulfuric acid, sodium molybdate and ascorbic acid concentrations and reaction coil length, which have relation to form the reduced complexes of molybdate and ions, on the detector response for phosphate and silicate ions were investigated. Under the optimized conditions (color-forming reactant, 50 mM sulfuric acid-10 mM sodium molybdate; reducing agent, 50 mM ascorbic acid; reaction coil length, 6 m), the calibration curves of phosphate and silicate ions were linear in the range of 50-2000 μg L⁻¹ as P and 250-10,000 μg L⁻¹ as Si. This method was successfully applied to water quality monitoring of Kurose-river watershed and it suggested that the effluent from a biological sewage treatment plant was significant source of phosphate ion in Kurose-river water.     

Gene transfer device utilizing micron-spiked electrodes produced by the self-organization phenomenon of Fe-alloy

In the diffusional phase transformation of two-phase alloys, the new phase precipitates form the matrix phase at specific temperatures, followed by the formation of a mixed microstructure comprising the precipitate and the matrix. It has been found that by specific chemical-etching treatment, the precipitate in Fe-25Cr-6Ni alloy projects substantially and clusters at the surface. The configuration of the precipitate has an extremely high aspect ratio: it is several microns in width and several tens of microns in length (known as micron-spiked). This study targets the development of a gene transfer device with a micro-spike produced based on the self-organization phenomenon of the Fe-25Cr-6Ni alloy. With this spike-projected device, we tried to efficiently transfer plasmid DNA into adherent cells by electric pulse-triggered gene transfer using a plasmid-loaded electrode (electroporation-based reverse transfection). The spiked structure was applied to a substrate of the device to allow efficient gene transfer into adherent cells, although the general substrate was flat and had a smooth surface. The results suggest that this unique spike-projected device has potential applications in gene transfer devices for the analysis of the human genome in the post-genome period.     

VO<Subscript>x</Subscript>/Zr–SBA-15 catalysts for selective oxidation of ethanol to acetaldehyde

Effect of zirconium presence in the silica framework and content and speciation of vanadium surface oxo-complexes on the catalytic behavior of VO_x/Zr–SBA-15 catalysts in oxidative dehydrogenation of ethanol was investigated. Experimental results bring evidence of successful incorporation of zirconium into ordered mesoporous silica framework with the preservation of ordered mesoporosity by hydrothermal template base synthesis method. The presence of zirconium in the SBA-15 framework increases reducibility of vanadium species and acidity of the catalysts. It is reflected in higher activity of vanadium species expressed as turn-over frequency (e.g., TOF of 20 h^?1 for 5%VO_x/Zr–SBA-15 sample in comparison with TOF of 12 h^?1 for 5%VO_x/SBA-15 sample) and also in significant decrease of selectivity to acetaldehyde (65% in comparison with 90% for mentioned samples) followed by increase in selectivity to ethylene (25% in comparison with 5%). This change in distribution of reaction products is related to stronger acidity character of surface OH groups and inhibition effect of formed water vapours on the oxidative dehydrogenation products (acetaldehyde). Catalytic data also reveal that oligomeric/polymeric tetrahedrally coordinated vanadium species exhibit higher activity in ethanol oxidative dehydrogenation than monomeric complexes. In addition, comparison of the catalytic performance of VO_x/Zr–SBA-15 catalysts with VO_x/SBA-15 catalysts showed that catalytic properties of VO_x/Zr–SBA-15 catalysts can be tuned by incorporation of controlled amount of zirconium into silica framework.