PtCu nanoparticles were synthesized with different pH and support conditionsusing radiochemical process. The nanoparticle structures were characterized bytransmission electron microscopy, inductively coupled plasma atomic emissionspectrometry, X-ray absorption spectroscopy, and X-ray diffraction techniques.The nanoparticle structure was relevant to the pH of the precursor solutions.The lattice parameter of PtCu alloy increased in high pH samples, whichindicates the critical effect of metal ion adsorption in precursor solution onnanoparticle structure.

Antiviral activity of metallic Ag nanoparticles immobilized on textile fabrics were investigated. The Ag nanoparticles synthesized by radiochemical process are firmly immobilized on the surface of support textile fabrics of cotton. Small Ag particles of about 2–4 nm were observed together with relatively large particles of more than 10 nm. The Ag nanoparticles showed antiviral activity against Influenza A and Feline Calicivirus. The antiviral activity significantly depended on the concentration of the Eagle’s minimal essential medium. It was implied that the surface passivation by inhibitory agent lead to the deactivation of metallic Ag nanoparticles.

Electrode catalysts composed of carbon supported PtRu nanoparticles (PtRu/C) synthesized by radiochemical process were annealed to control the PtRu substructure to enhance catalytic activity. The substructure of the PtRu nanoparticles synthesized by using high-energy electron beam under acidic condition was Pt-rich core/Ru-rich shell type, reflecting the redox potentials of each precursor ions. The material characterization techniques revealed that the reductive annealing led to the mixing of PtRu both in the core and on the surface. The sample with annealing temperature of 300°C for 5 hour showed the highest methanol oxidation current, 2.3 times higher than that obtained with before annealing.

Carbon supported Pt-SnO2 electrocatalysts with different Sn/Pt molar ratios were prepared by an electron beam irradiation method. Dissolved gas conditions in the vials irradiated with electron beam were controlled to air or Ar. The results of the material analyses showed that both Pt and SnO2 were immobilized onto carbon support in all catalysts. Bubbling Ar to the precursor solution led to steady change of metal contents in response to the precursor concentrations. The ethanol oxidation activity plotted against Sn/Pt ratio behaved differently with dissolved gas condition of the vial. This difference is discussed with supposed existing state of SnO2 in connection with the reduction process of Pt and Sn.

HoxEr1-xN (x=0.25, 0.5, 0.75) samples were synthesized by nitriding of HoxEr1-x alloy bars and their thermal conductivity κ were measured. The measured κ values were comparable to those of stainless steel and Er3Ni. Ho0.5Er0.5N showed the highest κ of the present three samples. The thermal diffusivity calculated from the κ and the specific heat indicates that Ho0.5Er0.5N is a very promising regenerator material for the cryocoolers. The electrical resistivity ρ was also measured as a function of temperature.

A nanoparticle catalyst of PtRuAu/C was synthesized by including an Au precursor in the radiolytic process for preparing a PtRu/C catalyst. Their methanol oxidation activity and electrochemical durability were measured by linear sweep voltammetry before and after potential cycling treatment. PtRuAu/C had a significantly higher durability than PtRu/C while maintaining a comparable high activity. The morphology and substructure of the nanoparticles were investigated by energy-dispersive x-ray spectroscopy, x-ray diffraction, and x-ray absorption fine structure spectroscopy. Metallic nanoparticles with diameters of about 2 nm were obtained; they probably had Pt-core/PtRu-shell structures. Transmission electron microscopy observations after potential cycling revealed that 2-nm-diameter nanoparticles containing Au did not coarsen, whereas nanoparticles without Au coarsened significantly to 3.7 nm. Some crystal defaults were observed in the coarsened particles, implying that the coarsening was caused by Ostwald ripening. The Au addition to catalyst particles consisting of PtRu inhibits coarsening and consequently improves the electrochemical durability.

Nanoparticle catalyst of PtRuAu/C for direct methanol fuel cell anodes was synthesized by a radiolytic process. Its methanol oxidation activity and the electrochemical durability were evaluated by using the linear sweep voltammetry and the cyclic voltammety. The Au addition significantly improved the durability in comparison with PtRu/C catalyst without losing its high activity. The atomic structure was characterized with techniques of the transmission electron microscopy, the X-ray diffraction, the X-ray fluorescence spectroscopy and the X-ray absorption fine structure. These results implied that the arrangement of Pt and Ru atoms in the PtRuAu/C has no significant difference from that without Au, possessing a structure of Pt rich core and PtRu alloy shell. We concluded that the improvement in durability could originate from these PtRu nanoparticles decorated with Au, but not from particles with high Au contents.

A magnetic refrigeration test was performed using a test device filled with spherical GdN material synthesized by the hot isostatic pressing (HIP) method. Refrigeration with an active magnetic regenerator cycle was tested in the temperature range between 48 and 66 K, with the field changing from 1.2 to 3.7 T and 2.0 to 4.0 T at upper and lower sides of the regenerator bed filled with the GdN spheres, respectively. Temperature spans about of 2 K were obtained at both sides, and the total temperature span in each cycle attained about 5 K. The specific heat of the material was measured to calculate the magnetic entropy change ΔS and the adiabatic temperature change ΔT induced by the magnetic field change ΔH. It was suggested that for a given ΔH, larger ΔS and ΔT can be exploited when demagnetized to lower H, especially, to zero field.

Catalysts in which Pt and Cu are immobilized on support particles of γ-Fe2O3 were synthesized by the radiolytic process and were evaluated for CO oxidation in a gas flow mixture (1% CO, 0.5% O2, 67.2% H2 and N2 balance) by measuring the CO concentration in the outlet gas. The Pt/Cu atomic ratios of the as-synthesized catalysts were determined to be 100:0, 90:10, 78:22, 50:50, 21:79, and 11:89, and the total metal loadings determined by chemical analyses were 10 wt%. Material characterization was performed using X-ray diffraction, X-ray absorption near edge structure, and transmission electron microscopy, and it was indicated that the composite catalysts consist of Pt-Cu bimetallic grains immobilized on the support at higher Pt-loading, while CuO with poor crystallinity is also observed at lower Pt-loading. The catalytic activity decreased as the Pt-loading was decreased to 50 at%, and also with increasing temperature. However, as the Pt-loading was further decreased, the activity contrariwise increased, and increased with increasing temperature up to 100 °C. The sample containing only 11 at% Pt exhibited the highest activity at 100 °C, which is higher than that of the commercial catalyst measured for comparison, and given at a lower temperature than that for the commercial catalyst. This enhanced activity, despite the low Pt-loading, could be attributed to oxygen supply via CuO from the O2-poor atmosphere to PtCu bimetallic grains trapping CO molecules. This new material is promising for use as a catalyst to purify hydrogen gas fed to a polymer electrolyte fuel cell.

The infrared astronomical satellite AKARI performed an all sky survey at six infrared bands. We report here on the calibration of the all-sky image data, observed in the four long wavelength bands with the FIS instrument (AKARI Far-infrared All Sky Survey : AFASS). The preliminary image attains a calibration uncertainty and sensitivity of better than ~ 30% and ~ 10 MJy str−1, respectively, for all four bands. The point spread function (PSF) is obtained via a stacking technique. The data are shown to be useful for exploring the internal structure and dust spectral energy distributions (SEDs) of nearby galaxies.

Carbon and nitrogen stable isotope ratios (δ13C and δ15N) have been used to study the structure of food webs. However, few studies have examined how a terrestrial food web can be depicted by this technique. We measured δ13C and δ15N in various consumers of four trophic groups (detritivores, herbivores, omnivores and predators), including vertebrates and invertebrates (14 orders, ≥24 families), as well as canopy and understorey leaves in a tropical rain forest in Malaysia. We found that δ13C and δ15N of the consumers differed significantly among the trophic groups. The predators had significantly higher δ13C than the herbivores, and were similar in δ13C to the detritivores, suggesting that most predators examined depend largely on below-ground food webs. δ15N was higher in predators than detritivores by about 3‰. The comparison of δ13C in plant materials and herbivores suggests that most herbivores are dependent on C fixed in the canopy layers. The vertebrates had significantly higher δ15N and δ13C than the invertebrates of the same trophic group, likely reflecting differences in the physiological processes and/or feeding habits. This study indicates that stable isotope techniques can help better understanding of the terrestrial food webs in terms of both trophic level and the linkage of above- and below-ground systems.

Bimetallic nanoparticles of PtCu and PtNi supported on iron oxide particles were synthesized by a new method employing a 4.8-MeV electron beam as a trigger for reduction of their aqueous ions, and their CO oxidation catalysis was evaluated to find activities enhanced by the alloying. Sample materials of PtCu (PtNi) bimetallic grains supported on γ-Fe2O3 particles were synthesized by irradiating with the electron beam a glass vial containing precursors in an aqueous solution. The vial contains aqueous ions of platinum and copper (nickel) and γ-Fe2O3 particles of average size of 30 nm. The irradiation induces water radiolysis generating reducing species, such as hydrated electrons, and metallic nanograins are formed and stabilized on the support material. The irradiation was finished in several seconds without using any organic solvent and any surfactant. The average grain sizes observed with a TEM were around 3 nm in diameter. XRD patterns of PtCu samples exhibited the FCC structure with peak shifts obeying the Vegard’s law at low Cu concentrations. X-ray absorption spectra measured at edges of the constituent elements indicated that Pt is in the metallic state and coordinates certainly with Cu or Ni. Catalytic activity of CO oxidation of the material was evaluated by measuring residual CO contents in air in contact with the sample material by using a gas-chromatograph. The activities of the PtCu and PtNi samples were higher than that of monolithic Pt on γ-Fe2O3. The correlation between the atomic structure in these nanograins and their activities was investigated, which indicated that the random alloy enhances the activity. These bimetallic nanoparticles are expected as catalysts for preferential oxidation of CO in hydrogen gas fed to fuel cells.

Composite nanoparticles consisting of gold and iron-oxide were radiochemically synthesized in aqueous solution systems by using polyethylene glycols. The gold particles with average diameter of 3 nm were firmly immobilized on the surface of the support iron-oxide nanoparticles. The composite nanoparticles specifically adsorbed sulfur-containing amino acids by a Au-S bonding.

We synthesized HoxEr1−xN (x =0.1, 0.3, 0.5, 0.7, 0.9) by the carbothermic reduction method. The magnetic entropy change, ΔS, which is an indicator of performance of magnetocaloric effect, MCE, was obtained from data sets of magnetization M (H, T) measured at various temperature, T, and magnetic field, H, through the Maxwell equations. The Thus obtained ΔS vs. T curves have peaks at temperatures depending on x in a range of 8–18 K. ΔS values of HoxEr1−xN expressed in terms of J K−1 m−3 were higher than those of intermetallic compounds of rare earth and transition metals previously reported. These ΔS peak plots are along a convex curve, which may indicate an interaction between the two components.

PtRu bimetallic nanoparticles supported on carbon nanoparticle (PtRu/C) catalysts were synthesized with radiation irradiation. The samples were structural analyzed by techniques of X-ray absorption fine structure (XAFS), transmission electron microscope (TEM) and X-ray diffraction (XRD). The results indicated that PtRu/C catalysts which prepared by an electron beam irradiation had more homogeneous atomic arrangement than that prepared by a gamma-ray irradiation. We found a clear correlation between the atomic structure and the catalytic activity of PtRu/C catalysts. These results supported the bi-functional mechanism.

SPICA is a cooled, single large-mirror space-telescope, which is under discussion as an succsesor of the ASTRO-F mission. One of the most ambitious challenges of the SPICA mission is the direct observations of exoplanets with a coronagraph instrument. We report cryogenic infrared optics to realize high quality wavefronts for the SPICA coronagraph.

The SPICA satellite will be launched by an H-IIA rocket to Sun-Earth L2 Halo orbit early in the 2010s. The SPICA telescope is a Ritchey-Chretien optics with 3.5m diameter primary mirror, and cooled down to 4.5 K in orbit by radiation cooling and mechanical cryo-coolers. Main working wavelengths are 5–200 micron. Advantages of the SPICA coronagraph are the infrared wavelenths where the contrast between planets and central stars are smaller than the optical wavelengths, and that the cooled space telescope consists of monolithic mirrors.

Development of light-weight cooled telescope is one of the most important tasks to realize SPICA. At the present, sintered SiC and carbon fiber reinforced SiC (C/SiC) composite are candidate materials for the mirrors, truss, and optical bench. For these materials, estimations and improvements of basic property and surface roughness in cryogenic temperatures have been carried out. Deformation of trial product mirrors by cooling is also examined.

We are developing cryogenic deformable mirrors (DMs) because wave front accuracy of the SPICA telescope is 0.35 micron RMS, which is not enough for our coronagraphic instrument. For MEMS (Micro Electro Mechanical System) DM and some others, measurements of thermal deformation by cooling, electrical response, and heat generation are undergoing. Developments of a tip-tilt system for cryogenic usage started to cancel vibration caused by the cryo-coolers and other components and to realize a diffraction limit resolution. The first result of our binary mask coronagraph experiment is also shown.

Nano-sized PtRu catalysts supported on carbon nanoparticles were synthesized by a polyol process. The PtRu catalyst prepared at pH=3 indicated higher catalysis for methanol oxidation than one prepared at pH=5.5. The samples were analyzed by techniques of the extended X-ray absorption fine structure (EXAFS), transmission electron microscope (TEM), X-ray diffraction (XRD) and X-ray fluorescence (XRF). Their results showed that the pH of the precursor solution during the polyol process affected the substructure of the PtRu nanoparticles. The correlation of the substructure with the catalytic activity was studied.

Amounts of oligonucleotides adsorbed onto the Au/γ-Fe2O3 composite nanoparticles synthesized by gamma-ray irradiation and picked up by a magnet were evaluated using fluorescence technique. The adsorbing capacity of the oligonucleotides on our nanoparticles are larger than a commercial magnetic beads for a separation of biomolecules.

Z-type hexagonal ferrite samples in which cobalt is partially substituted with iron, Ba3Co2-xFe24+xO41 (x = 0, 0.2, 0.4, 0.6), were prepared by the ceramic process under a sintering oxygen partial pressure, PO2 = 21.3 or 101.3 kPa, at 1573 K. The influence of the substitution ratio and oxygen partial pressure on the complex permeability was investigated by examining the cobalt distribution over various cation sites in the Z-type structure with the neutron powder diffraction analysis performed at 294 K (neutron wave length was 1.006Å). The neutron diffraction pattern was studied with the Rietveld method. A significant difference in the preferential occupation of cobalt on various kind of cation sites was observed between the samples obtained under PO2 = 21.3 and 101.3 kPa. Almost all cobalt atoms are on the 12k octahedral site at the boundary between S- and R-blocks in the sample of x = 0, PO2 = 21.3 kPa. On the other hand, in the sample of x = 0, PO2 = 101.3 kPa, cobalt atoms are as well on other sites, the 12k octahedral site at the boundary between S- and T-blocks, the 4e tetrahedral site in S-block, the 2a octahedral site in T-block and the 2d five fold (trigonal bypiramid) site in T-block.

One of the most important results of the IRAS survey is the discovery of a class of “Luminous Infrared Galaxies” (LIGs), which emit most of the energy in the infrared and are the dominant population in the local universe at luminosities above 1011L⊙ (e.g., Sanders & Mirabel 1996). All LIGs appear to be extremely rich in molecular gas, and many of them show evidence of recent interacting/merging activities. Hence it is now accepted that strong interactions of gas-rich galaxies triggers large central concentration of molecular gas, and makes optimal conditions for both enormous nuclear starbursts and building and/or fueling AGN. Actually, various observations show evidence of starburst activity as well as that of AGN in many LIGs (Sanders & Mirabel 1996).