Radon mitigation using an air cleaner

Room experiments were conducted to investigate the effects of an air cleaner on radon mitigation. Radon concentration, equilibrium equivalent radon concentration and unattached fraction were measured during the experiments. Two types of filtration were tested using the air cleaner which has a high efficiency particulate air filter (HEPA-filter) and a deodorizing activated carbon (carbon-filter). One is the filtration with the HEPA-filter plus carbon-filter and the other is the filtration with only the HEPA-filter. The effective doses from radon progeny were significantly decreased. Both filtration methods were effective for the mitigation of effective dose due to radon progeny.     

Characterization of airborne radon released by domestic showering and the use of a washing machine

Water originated from groundwater systems can have relatively high concentration of radon. In many situations, radon is released from the water and mixes with the indoor air. In the present study, laboratory experiments were conducted to characterize the airborne radon released by showering and the use of a washing machine. The followings were discussed: (1) a comparison between the loss of waterborne radon and the increase of airborne radon, (2) time-related changes in airborne radon after the water use, (3) changes in the equilibrium factor, and (4) the relationship between radon concentration and the distance from the source of radon release.     

Ion-channeling analysis for epitaxial YBa2Cu3Ox superconducting thin films by laser deposition

Rutherford backscattering/channeling has been applied to study structures of as-deposited epitaxial YBa₂Cu₃O_x thin films prepared on {100}SrTiO₃ by laser deposition. The epitaxial growth has been proved by a planar channeling experiment and transmission electron microscopy. An axial angular yield profile for barium along the c-axis has ideal characters of compensating shoulders and of a flat region at the bottom of the channeling dip. The thermal vibration amplitude, which has been determined from a half-angle of the axial angular yield profile by using Gemmell's channeling model for polyatomic crystals, is compared to those from diffraction experiments.     

Kink motion in poly(vinylidene fluoride) form I

The diffuse-streak x-ray scattering intensity from poly(vinylidene fluoride) form I, which is caused by kink bands with GT_n? (n odd) conformation contained in the crystallite, decreases with increasing temperature, while the intensity of the 001 reflection does not change. This is attributed to the disappearance of the kink bands in the crystallite, not to partial melting of crystallites containing kink bands. The disappearance of the kink bands suggests that kink motion takes place in the crystallite. Plots of the intensity of diffuse-streak scattering, estimated from the asymmetric part of the 001 reflection, against 1/T roughly give ΔH_v = ?4.6 kcal/mol. This suggests that the kink band is energetically more stable than the regular structure of form I.     

Positive muon spin precession in magnetic oxides MnO and V2O3; local fields and phase transition

Muon spin precession is observed in the ordered state of antiferromagnetic oxides MnO and V₂O₃. An anomalous temperature dependence of muon precession frequency and the absence of critical behavior atT _N are found in MnO and a hysterisis of the transition temperature is observed in V₂O₃. These results are explained in terras of the crystal distortion of these materials belowT _N.We would like to thank Dr. T. Suzuki, Dr. S. Takagi, Dr. Y. Kuno and Dr. C.Y. Huang for their help in the measurements, and Dr. K. Kosuge and Dr. S. Kachi for providing the specimen of V₂O₃. We are grateful to the financial support from Japan Society for Promotion of Science.     

Spin fluctuation of itinerant electrons in MnSi probed by μ+

Conclusion To our knowlge, this is the first experimental work to show the divergent behavior of 1/T₁ at T_C in weak itinerant ferromagnetic systems, and we conclude that there is general agreement between the present results and the SCR theory.Work supported by Japan Society for the Promotion of Science, the Toray Science Foundation, the Grant-in-Aid of the Japanese Ministry of Education, Culture and Science, and the Atomic Energy Control Board and National Research Council of Canada.