1.6 μm band double pass fiber Raman amplifiers using Raman fiber oscillator

We propose double pass fiber Raman amplifier schemes based on Raman fiber oscillator in order to amplify optical signal with wavelengths from 1610 to 1650 nm efficiently. We experimentally demonstrate that the proposed double pass amplifier scheme has enhanced gain characteristics compared to a conventional single pass scheme. We also demonstrate a scheme for the proposed double pass amplifier to have small gain variation over the wavelength range by using two fiber Bragg gratings with different center wavelengths.     

A novel infrared absorbing structure for uncooled infrared detector

In this paper, we proposed a novel infrared absorbing structure for uncooled infrared detectors. The infrared absorber makes use of a quarter-wavelength structure composed of a dielectric layer, a protecting layer, an active layer, a supporting layer and a reflecting layer. Sputtered amorphous silicon is used as a dielectric layer because of its high refractive index. We fabricated the uncooled microbolometer with the proposed infrared absorbing structure by surface micromachining method. Then we characterized various bolometric properties such as thermal conductance, thermal time constant, responsivity and infrared absorptance. The fabricated bolometer showed the thermal conductance of 6.72 × 10⁻⁷ W/K, the thermal mass of 4.43 × 10⁻⁹ J/K, the thermal time constant of 6.6 ms and the responsivity of 7.76 × 10³ V/W at 10 Hz chopper frequency and 9.22 μA bias current. From the results, the estimated absorptance is about 80%. We expect that the proposed absorbing structure shows high infrared absorption and high performance of uncooled microbolometer.     

K* 0 Σ+ Photoproduction with Evidence for the Kappa Meson Exchange at SPring-8/LEPS

Recently, LEPS collaboration reported the parity spin asymmetry for the γ p → K* ⁰Σ⁺ reaction using linearly polarized photons at beam energies from 1.85 to 2.96 GeV. The parity spin asymmetry ( ${P_{\sigma} = 2\rho^{1}_{1-1} - \rho^{1}_{00}}$ ) was obtained, with large positive asymmetry at forward angles. This supports that natural-parity exchange is dominant at forward angles for K* ⁰Σ⁺ photoproduction, which is consistent with κ meson-exchange. The differential cross sections for the γ p → K* ⁰Σ⁺ reaction are presented at forward angles averaged over all beam energies. There is good agreement with the differential cross sections from the CLAS and the CBELSA/TAPS collaborations.     

Chemical bath deposition of CdS channel layer for fabrication of low temperature-processed thin-film-transistors

～66 nm thick CdS film with a hexagonal structure was uniformly generated via a low temperature-processed chemical bath deposition at 80 °C using a complexing agent of ethylenediaminetetraacetic acid and its crystal structure, surface morphology, optical transmittance, and Raman scattering property were measured. Grown CdS film was used as a channel layer for the fabrication of bottom-gate, top-contact thin-film-transistor (TFT). The TFT device with 60 °C-dried channel layer exhibited a poor electrical performance of on-to-off drain current ratio (I_on/I_off) of 5.1 × 10³ and saturated channel mobility (μ_sat) of 0.10 cm²/Vs. However, upon annealing at 350 °C, substantially improved electrical characteristics resulted, showing I_on/I_off of 5.9 × 10⁷ and μ_sat of 5.07 cm²/Vs. Furthermore, CdS channel layer was chemically deposited in an identical way on a transparent substrate of SiN_x/ITO/glass as part of transparent TFT fabrication, resulting in I_on/I_off of 5.8 × 10⁷ and μ_sat of 2.50 cm²/Vs.     

Compatibilizing effect of polyarylate-polystyrene block copolymer in polyarylate/polystyrene blends

The compatibilizing effect of polyarylate-polystyrene (PAR-PS) block copolymer prepared from macroazo initiator was examined in polyarylate/polystyrene blends from the view-points of morphology, density, and thermal, mechanical, and rheological properties. PARPS block copolymer enhanced the mutual dissolution of the homopolymers. Reduced dispersed-domain size and increased density showed the efficiency of the block copolymer as a compatibilizing agent. Results from mechanical and rheological properties could also be explained by the compatibilizing effect of PAR-PS block copolymer in the blends. © 1994 John Wiley & Sons, Inc.     

Spectral correlation in incommensurate multiwalled carbon nanotubes

We investigate the energy spectra of clean incommensurate double-walled carbon nanotubes, and find that the overall spectral properties are described by the critical statistics similar to that known in the Anderson metal-insulator transition. In the energy spectra, there exist three different regimes characterized by Wigner-Dyson, Poisson, and semi-Poisson distributions. This feature implies that the electron transport in incommensurate multiwalled nanotubes can be either diffusive, ballistic, or intermediate between them, depending on the position of the Fermi energy.     

Protein micropatterning on bifunctional organic-inorganic sol-gel hybrid materials

Active protein micropatterns and microarrays made by selective localization are popular candidates for medical diagnostics, such as biosensors, bioMEMS, and basic protein studies. In this paper, we present a simple fabrication process of thick (approximately 20 microm) protein micropatterning using capillary force lithography with bifunctional sol-gel hybrid materials. Because bifunctional sol-gel hybrid material can have both an amine function for linking with protein and a methacryl function for photocuring, proteins such as streptavidin can be immobilized directly on thick bifunctional sol-gel hybrid micropatterns. Another advantage of the bifunctional sol-gel hybrid materials is the high selective stability of the amine group on bifunctional sol-gel hybrid patterns. Because amine function is regularly contained in each siloxane oligomers, immobilizing sites for streptavidin are widely distributed on the surface of thick hybrid micropatterns. The micropatterning processes of active proteins using efficient bifunctional sol-gel hybrid materials will be useful for the development of future bioengineered systems because they can save several processing steps and reduce costs.     

Complement activation by sulfonated poly(ethylene glycol)-acrylate copolymers through alternative pathway

Previously, novel poly(ethylene glycol) (PEG) and sulfonated PEG acrylate (PEG-SO₃A/OA) copolymers were prepared as coating and/or blending materials for biomedical applications. Surfaces modified with copolymers exhibited increased anti-coagulation properties and decreased plasma adsorption level due to increased hydrophilic properties and reorientation characteristics of PEG/PEG-SO₃A chains in water phase. As continuation study, anti-complement effects of PEG-SO₃/OA copolymers were investigated in vitro, and compared with those of low-density polyethylene (LDPE) and PEG/OA. C3 activation by PEG-SO₃/OA samples was lower than that by PEG/OA samples, which was attributed to decreased surface nucleophile level of samples. PEG-SO₃/OA samples increased inhibition of Bb production, resulting in decreased C5 activation. Owing to reduced activations of C3 and C5, PEG-SO₃/OA samples markedly decreased SC5b-9 levels in plasma.     

A new way to increase performance of oxide electrode for oxygen reduction using grain growth inhibitor

Nickel oxide was introduced as a grain growth inhibitor into Ba_0.5Sr_0.5Co_0.8Fe_0.2O_3 − δ (BSCF) electrode to increase its activity for oxygen reduction reaction. Small amount of NiO can effectively suppress the grain growth of BSCF by spinning the grain boundary and thus increase the electrode surface area, while the particle connection is not obviously affected. Electrochemical impedance spectra of symmetric cells indicate that the electrode activity for oxygen reduction is indeed effectively improved by introducing NiO additive. At 600 °C, area specific resistance of BSCF+5wt.% NiO is about 36.5% lower than that of pure BSCF electrode. Single cell tests also demonstrate an improved cell power output by introducing NiO additive. It implies that the adoption of a sintering inhibitor may be a facile and practical way to increase electrode activity for oxygen reduction.