We initiated a long-term and highly frequent monitoring project toward 442 methanol masers at 6.7 GHz (Dec >−30 deg) using the Hitachi 32-m radio telescope in December 2012. The observations have been carried out daily, monitoring a spectrum of each source with intervals of 9–10 days. In September 2015, the number of the target sources and intervals were redesigned into 143 and 4–5 days, respectively. This monitoring provides us complete information on how many sources show periodic flux variations in high-mass star-forming regions, which have been detected in 20 sources with periods of 29.5–668 days so far (e.g., Goedhart et al. 2004). We have already obtained new detections of periodic flux variations in 31 methanol sources with periods of 22–409 days. These periodic flux variations must be a unique tool to investigate high-mass protostars themselves and their circumstellar structure on a very tiny spatial scale of 0.1–1 au.

We showed that it is feasible to measure the mass of a single star by observing the variation of gravitational deflection caused by the orbital motion of the Earth. When the distance of a star is less than 60 pc and some appropriate sources are within 1 arcsec. in its background, not only the distance but also the mass of the star may be determined by measuring the deflection with an accuracy of 10 μ arcsec. In the case of photometric microlensing by a MACHO, the observation of astrometric gravitational deflection is also useful. By measuring the separation between the primary image and the secondary image, the ratio of mass to distance of the MACHO will be obtained. Further, the orbital motion of the Earth modifying the light curve of the source is discussed.

Several scales' density fluctuations which exist in the early universe will first gravitationally collapse along one axis and make pancake-like structures. If the collapsed baryonic pancake heats up over 104 K by shock formation, radiative cooling begins to work and mass accretion toward the central region will advance. Because of this effect, mass fraction of the high density layer becomes large. Densities and widths of the layers will reflect masses of structures (e.g. galaxy) which will be formed after caustics. In this respect, we assumed an Einstein-de Sitter universe dominated by cold dark matter (Ω DM = 0.9) and investigated the evolutions of fluctuations numerically using one-dimensional hydrodynamic plus N-body codes. We applied a new method for larger fluctuation scales; it is a hybrid method of Eulerian PPM and Zeldovich approximation and it can simulate around the central pancake region with high accuracy.

Extended abstract of a paper presented at Microscopy and Microanalysis 2013 in Indianapolis, Indiana, USA, August 4 – August 8, 2013.

Extended abstract of a paper presented at Microscopy and Microanalysis 2012 in Phoenix, Arizona, USA, July 29 – August 2, 2012.

Extended abstract of a paper presented at Microscopy and Microanalysis 2011 in Nashville, Tennessee, USA, August 7–August 11, 2011.

Extended abstract of a paper presented at Microscopy and Microanalysis 2011 in Nashville, Tennessee, USA, August 7–August 11, 2011.

Extended abstract of a paper presented at Microscopy and Microanalysis 2011 in Nashville, Tennessee, USA, August 7–August 11, 2011.

Extended abstract of a paper presented at Microscopy and Microanalysis 2011 in Nashville, Tennessee, USA, August 7–August 11, 2011.

Photoluminescence characteristics of porous silicon layers (PSLs) doped with Er or Yb ions are studied. 10μm thick PSLs with a luminescence centered at ∼ 0.8μm are formed by anodic etching of p-type silicon wafers of several Ω-cm resistivity. Rare-earth ions are electrochemically incorporated into PSLs. The Er3+-related luminescence at 1.54μm as well as the Yb3+-related luminescence at 1.0μm is observed at room temperature after annealing at high temperatures (>900°C). The Er-related luminescence is enhanced after annealing in O2, whereas the Yb3+-related luminescence needs oxygen-free atmosphere (H2) for the optical activation. The luminescence decay time of the rare earth ions as well as the host PSLs is measured and the energy transfer mechanism is discussed.

The optimum materials design in microstructural control could be developed for the highstrain-rate superplastic materials in the industrial scale. In the present work, it is reported that the high-performance-engine pistons with near-net-shape can be fabricated by the superplastic forging technology in the high-strain-rate superplastic PM Al-Si based alloy, which is produced by using this optimum materials design.

Cavitation behaviors related to ferrous primary crystals have been investigated at a temperature of 653 K and a strain rate of 10−3/s for Al-4.5%Mg-0.05%Fe and Al-4.5%Mg-0.2%Fe alloys which have a grain size of 50;Lm. The alloys constantly exhibited a large elongation-to-failure above 300% at the temperature of 653 K and strain rate of 10−3/s. Cavitation was increased by increasing the iron content. Most cavities were nucleated at the interface between the ferrous primary crystal and matrix and elongated parallel to the tensile direction. The experimental critical diameter of the primary crystal, above which cavity is nucleated, was 1.5 µm at the grain boundary and 0.5µm at grain interior, which were very close to double the critical diffusion length.

Compositional ordering is observed in essentially all IIIN semiconductor alloys. The mechanism leading to the specific ordered structures formed is only now beginning to be understood. It is intimately related to the atomic-scale physical processes occurring on the surface during epitaxial growth, specifically surface reconstruction and the attachment of atoms at steps. This paper will emphasize the use of surface analytic techniques to better understand the ordering processes during organometallic vapor phase epitaxial growth of GalnP. Surface photo absorption has been used to determine, for the first time, that the surface reconstruction is (2×4)-like during growth of GalnP with Cu-Pt ordering. By increasing the growth temperature and/or decreasing the V/Ill ratio the concentration of phosphorus dimers characteristic of the (2×4) structure is observed to decrease in tandem with a decrease in the degree of order measured in the epitaxial layers. This suggests that formation of the (2×4) reconstruction is necessary for formation of the Cu-Pt ordered structure.

Atomic force microscopy was used to examine the step structure. For exactly (001)-oriented substrates, growth at low V/Ill ratios produces islands surrounded by single monolayer steps. Increasing the V/Ill ratio leads to the formation of bilayer steps approximately 6 Å high. A similar change in the structure of steps is observed in the vicinal regions for substrates misoriented to produce [110] steps. This phenomenon is interpreted in terms of the stabilization, at high V/Ill ratios, of the (2×2) reconstruction on the (111)B regions of the bilayer steps. This may also have an effect on formation of the Cu-Pt ordered structure.

By changing the substrate temperature or the input partial pressure of the phosphorus precursor, the degree of order and, hence, the bandgap energy of GalnP, can be modulated during growth. This has allowed the production of a variety of single and double heterostructures. The heterostructures produced by changing the temperature from 740 to 620°C and from 620 to 520°C are abrupt. The heterostructures formed by changing the phosphine flow rate are not. The ordered structure in the lower layer persists into the upper layer. This may be an indication of the importance of the step structure.

Extended abstract of a paper presented at Microscopy and Microanalysis 2010 in Portland, Oregon, USA, August 1 – August 5, 2010.