Application of the micro-PIXE technique for analyzing arsenic in biomat and lower plants of lichen and mosses around an arsenic mine site, at Gunma, Japan

Microhabitats of bacteria (biomat) and lower plants, such as lichen and mosses, are known to accumulate hazardous elements. Since the concentration of hazardous elements in the environment is quite low, we have applied the in-air μ-PIXE (particle induced X-ray emission) system developed in the TIARA facility of JAERI, which has low concentration detection limit of ppm, to measure As, one of the hazardous elements, distributions in biomat, lichen and mosses observed around an abandoned As mine site in Gunma, Japan to elucidate the applicability of these biomat and lower plants as bio-indicators of As. Spatial distributions of As, Fe, Si and S in all biomat, lichen and moss collected within 3 m from the mine entrance indicate that As is localized, and is associated with silicate and Fe-containing compounds. In addition, the intensity ratio of peak area for As to Fe in μ-PIXE spectrum of the moss collected from the concrete wall at 3 m downstream of the mine water discharge position is different from those of the lower plants on the rock near the closed entrance, but is the same as that of biomat formed at the mine water discharge position. This indicates that As trapped by the moss on the concrete wall probably has the same origin as the biomat. It is concluded that application of μ-PIXE analysis to the measurement of As in the lower plants and biomat gives not only the distribution of the hazardous element of As, but also the information of the origin.     

Hybrid optical circulator using garnet-quartz composite embedded in planar waveguides

A novel hybrid configuration of optical circulator is presented. A Garnet-Quartz composite (GQC), which is comprised of four quarter-wave plates and Faraday rotator, is embedded into a groove formed across the branching waveguides pair of Mach-Zehnder interferometer. Optical path difference of the pair is 0 rad for forward path, whereas /spl pi/ for backward path with the GQC, realizing nonreciprocal operation. The forward-to-reverse isolation of 16.2-29.8 dB and the insertion loss of 8.8-9.4 dB are obtained.     

He-Cd+white light laser by a novel tube structure

A newly designed external cathode type He-Cd+ hollow-cathode white light laser has been realized by using a "twin cathode" and a cylindrical grid electrode which is distributed coaxially along the rod anode. The electric input power of this system is 300 V, 1 A, and 300 W, almost double that of the flute type, 250 V, 0.6 A, and 150 W, but the cathode temperature is almost the same in both systems. The output power of the blue laser line was increased over that of the flute and hybrid hole types, while that of the green and red laser lines could not exceed both types.     

Experimental Determination of Phase Equilibria in the Co-Cr-Ni System

The phase equilibria between the γ (A1) and liquid phases and those between the γ, ε (A3), σ (D8_b) and α (A2) phases at temperatures between 750 and 1300 °C in the Co-Cr-Ni system were determined by differential scanning calorimetry and electron probe microanalysis. It was found that the γ solidus and liquidus temperatures decrease with increasing Cr or Ni content and that the difference between them increases with increasing Cr content. The phase equilibria at 800, 900, 1000, 1100, 1200 and 1300 °C were determined using two- or three-phase alloys, and the phase boundaries due to the magnetically induced phase separation in the γ and ε phases were also observed at 850, 800 and 750 °C by the diffusion couple method.     

No. 4Vol. 42, No. 2, pp. 102–109, 2008A novel water-based sunscreen gel using a polymer – zinc oxide composite

Conventional sunscreen products generally must strike a compromise between efficacy and product feel; the hydrophobic ingredients that provide the sun protection generally impart an unpleasant, greasy feel and the greater the SPF rating, the worse the greasy feel. We tested an idea that a water-based sunscreen gel formulation containing inorganic UV absorbers would provide an effective way to address these problems. Our goal was to find a way to disperse inorganic sunscreen materials in water and to incorporate them into a water-based gel which would provide a more pleasant product feel. After extensive research we discovered a polymer-zinc oxide composite (P-ZnO) with high UV protective effect and high dispersibility in water. In dried powdered form, P-ZnO can be easily dispersed in water. P-ZnO makes it possible to formulate a gel-type sunscreen, which is not possible using commercially available inorganic powders. The composite size of P-ZnO is about 500 nm and its structure consists of a dense aggregate of nano-ZnO having a size distribution in the 5–10 nm range and amorphous layers of poly acrylic acid coating zinc oxide to control the particle growth, block surface activity and prevent aggregation. The water-based P-ZnO sunscreen gel offers UV protection comparable to conventional products in a delivery vehicle that is much more pleasant to use.