Report of test on the deterioration of former geological hut at Syowa Station

In January 1957 the First Japanese Antarctic Research Expedition built a prefabricated living hut at Syowa Station, and this hut has been used as a laboratory for geological study, named Geology Hut. Because of aging of finishing and interior materials, the hut was dismantled in January 1981 and brought to Japan in April 1981. To investigate the deterioration of building materials, one floor panel and two wall panels were subjected to the following four tests and their strength was compared with the original strength : Bending test of panel; residual strength of adhesion used in wood lamination; strength test of panel core; test of heat conductivity and physical properties. Test results indicated no appreciable deterioration of building materials and these materials may still stand good for future use

Emission and detection of terahertz radiation using two-dimensional plasmons in semiconductor nanoheterostructures for nondestructive evaluations

International audienceThe recent advances in emission and detection of terahertz radiation using two-dimensional (2-D) plasmons in semiconductor nanoheterostructures for nondestructive evaluations are reviewed. The 2-D plasmon resonance is introduced as the operation principle for broadband emission and detection of terahertz radiation. The device structure is based on a high-electron-mobility transistor and incorporates the authors' original asymmetrically interdigitated dual-grating gates. Excellent THz emission and detection performances are experimentally demonstrated by using InAlAs/InGaAs/InP and/or InGaP/InGaAs/GaAs heterostructure material systems. Their applications to nondestructive material evaluation based on THz imaging are also presented

Irradiation system of ions (H-Xe) for biological studies near the Bragg peak

We have developed a new system for irradiating biological samples in air with ions from H to Xe below 6.0MeV∕nucleon near the Bragg peak. The irradiation system can provide ion beams with 20‐mm diameter of which the central area of 100mm2 is uniform in fluence rate within a standard deviation of ±10%. For each ion, the linear energy transfer is selectable by irradiation positions in air, from the lowest at the surface of a vacuum window to the highest at the Bragg peak, for example, from 281 to 977 keV/μm for C ions. A wide range of fluence rates, 10−3–104ions∕μm2∕s, can be provided by the system, which makes it possible to irradiate a variety of biological samples with different target sizes, from small plasmid DNA to living mammalian cells. The ion fluence irradiated to each sample is calculated from the output of the secondary electron monitor using the linear relationship between the output and ion fluence measured at the sample position by CR-39 track detectors. Survival curves and visualization of NBS1 foci for human cells are presented as examples of preliminary experiments using C ions near the Bragg peak