Influence of Oxidation in Starting Material Sn on Electric Transport Properties of SnSe Single Crystals

We found that the electronic transport property of SnSe single crystals was sensitively affected by oxidation in raw Sn. Semiconducting SnSe single crystals were obtained by using Sn of grain form as a starting material while powder Sn resulted in metallic SnSe. X-ray photoelectron spectroscopy analysis revealed that the surfaces of raw Sn were oxidized, which volume fraction is lower in grain Sn. This indicates that the amount of oxygen in raw Sn is the key factor for the electronic transport property of SnSe

Migration of tremor locations before the 2008 eruption of Meakandake Volcano, Hokkaido, Japan

We estimate the locations of three tremor sequences, denoted A, B, and C, that occurred before the 2008 eruption at Meakandake volcano, eastern Hokkaido, Japan, using the spatial distribution of seismic amplitudes of volcanic tremor. Although we used only five seismic stations, we could estimate the locations of three tremor sequences. We find two different tremor source areas: those of Tremor A located about 2 km southwest of the erupted crater (Area A) and the other about 1 km southeast to south of the crater as that of the Tremor C (Area B). The location of an early phase of the Tremor B is estimated in Area A while the location of its later phase appears to connect the two areas. This location migration during Tremor B occurred simultaneously with other important geophysical phenomena before the eruption event, as suggested by geodetic and geomagnetic studies. Our findings of the two tremor locations of the tremor sequences and location migration during Tremor Bmay be important for future monitoring activities at Meakandake volcano, particularly to forecast the location of a possible phreatic eruption

Estimation of relative source locations from seismic amplitude : application to earthquakes and tremors at Meakandake volcano, eastern Hokkaido, Japan

Although seismic amplitudes can be used to estimate event locations for volcanic tremors and other seismic events with unclear phase arrival times, the precision of such estimates is strongly affected by site amplification factors. Therefore, reduction of the influence of site amplification will allow more precise estimation of event locations by this method. Here, we propose a new method to estimate relative event locations using seismic amplitudes. We use the amplitude ratio between two seismic events at a given station to cancel out the effect of the site amplification factor at that station. By assuming that the difference between the hypocentral distances of these events is much smaller than their hypocentral distances themselves, we derive a system of linear equations for the differences in relative event locations. This formulation is similar to that of a master event location method that uses differences in phase arrival times. We applied our new method to earthquakes and tremors at Meakandake volcano, eastern Hokkaido, Japan. Comparison of the hypocentral distributions of volcano-tectonic earthquakes obtained thereby with those obtained from phase arrival times confirmed the validity of our new method. Moreover, our method clearly identified source migration among three source regions in the tremor on 16 November 2008, consistent with previous interpretations of other geophysical observations in our study area. Our method will thus be useful for detailed analyses of seismic events whose onset times are ambiguous

A Liquid Chromatography-Mass Spectrometry Method to Study the Interaction between Membrane Proteins and Low-Molecular-Weight Compound Mixtures

Molecular interaction analysis is an essential technique for the study of biomolecular functions and the development of new drugs. Most current methods generally require manipulation to immobilize or label molecules, and require advance identification of at least one of the two molecules in the reaction. In this study, we succeeded in detecting the interaction of low-molecular-weight (LMW) compounds with a membrane protein mixture derived from cultured cells expressing target membrane proteins by using the size exclusion chromatography-mass spectrometry (SEC-MS) method under the condition of 0.001% lauryl maltose neopentyl glycol as detergent and atmospheric pressure chemical ionization. This method allowed us to analyze the interaction of a mixture of medicinal herbal ingredients with a mixture of membrane proteins to identify the two interacting ingredients. As it does not require specialized equipment (e.g., a two-dimensional liquid chromatography system), this SEC-MS method enables the analysis of interactions between LMW compounds and relatively high-expressed membrane proteins without immobilization or derivatization of the molecules