Direct Observation of Mono-, Bi-, and Tri-layer Charge Density Waves in 1T-TaS_2 by Transmission Electron Microscopy without a Substrate

Charge-density-waves (CDW) which occur mainly in low-dimensional systems have a macroscopic wave function similar to superfluids and superconductors. Kosterlitz-Thouless (KT) transition is observed in superfluids and superconductors, but the presence of KT transition in ultra-thin CDW systems has been an open problem. We report the direct real-space observation of CDWs with new order states in mono-, bi-, and tri-layer 1T-TaS_2 crystal by using a low voltage scanning-transmission-electron-microscope (STEM) without a substrate. This method is ideal to observe local atomic structures and possible defects. We clearly observed that the mono-layer crystal has a new triclinic stripe CDW order without the triple q condition q_1 + q_2 + q_3 = 0. A strong electron-phonon interaction gives rise to new crevasse (line) type defects instead of disclination (point) type defects due to the KT transition. These results reaffirm the importance of the electron-phonon interaction in mono-layer nanophysics.Comment: 5 figures, 1 tabl

‘Successful’ participation in intercultural exchange: Tensions in American-Japanese telecollaboration

The concept of successful participation is context-dependent. Learners have different definitions, which are subject to potential tension in the manner of participation that affects other aspects of the interaction. Drawing on activity theory (Vygotsky, 1987), the present study analyzes tensions that emerged during a six-week telecollaborative project between American learners of Japanese (AMU students) and Japanese learners of English (JPU students) through their understandings of successful participation. Transpacific dyads engaged in online discussions regarding assigned topics and a series of reflective tasks. Using a three-stage grounded theory data coding strategy, major contradictions are identified and analyzed. The findings suggest emergent contradictions in two dyads deriving from differences in the definition of participation. In one dyad, the JPU participant negotiated the imbalanced division of labor due to her passiveness by intentionally changing her participatory behavior. In the other dyad, the AMU participant displayed frustration and disappointment by his JPU partner whose definition of successful participation comprised prompt responses instead of proactive engagement in the discussion. These two cases illustrate how learners’ understandings of successful participation informed their actions and how local definitions affected their overall evaluation of the interaction

The electronic structures and magnetic properties of perovskite ruthenates from constrained orbital hybridization calculations

We introduce a method to analyze the effect of hybridization by shifting corresponding atomic levels using external potentials. Based on this approach, we study perovskite ruthenates,\ and unambiguously identify that the covalency between the \textit{A}-site cation and O ion will modify the Ru-O hybridization and change the density of state at Fermi level, consequently affect the magnetic properties significantly. We also study the effect of pressure and reveal that hydrostatic pressure has a small effect on the Ru-O-Ru bond angle of SrRuO$_{3}$, while it will decrease the Ru-O length and increase the band width significantly. Therefore, the magnetic ordering temperature will decrease monotonically with pressure

Discharge Behavior of Water-Activated Magnesium Battery

Water-activated magnesium batteries possess several favorable attributes for energy storage and lighting sources. In this chapter, a portable-sized magnesium battery which consisted of MnO2 cathodes and magnesium alloy anodes, being activated by drops of water, was investigated. The anode and cathode potential as well as their electrochemical impedance under a constant current load was monitored to evaluate the effect of water content, cell stacking, and discharging cycles. It was revealed that the discharge behavior was initially controlled by the depletion of water, followed by the cease of cathode reaction and the accumulation of Mg(OH)2 at anode. The problem of low anode efficiency caused by stacking cells was analyzed, and its countermeasure was proposed. Several approaches to improve the battery performance were also presented

〔研究ノート〕水素水の抗酸化力

　　Today we find several varieties of hydrogen water in stores. This suggests that there has been a growing interest in this product among people who are concerned about their health and beauty. Hydrogen can be effective in reducing excess active oxygen in the body, and hydrogen water contains molecular hydrogen. Therefore the author measured antioxidative activities of 5 kinds of commercial hydrogen water and for comparison 2 kinds of alkaline ionized water using the Biological Anti-oxidant Potential（BAP）testing method. Commercial hydrogen waters were found to have antioxidative activities of about 200 to 450μmol/L. One of the alkaline ionized waters showed antioxidative activity of about 430μmol/L