An anticorrosive magnesium/carbon nanotube composite

"Here, we report a drastically improved anticorrosive characteristic of magnesium alloy composites with the introduction of multiwalled carbon nanotubes. Highly depressed corrosion of nanotube-filled magnesium composite in salt water is due to the formation of stable oxide films along the grain boundaries of magnesium. Our results indicate that carbon nanotube acted as effective multifunctional filler to improve both mechanical and anticorrosive performances of magnesium alloy.

Controlled growth of one-dimensional clusters of molybdenum atoms using double-walled carbon nanotube templating

"We report the controlled growth of one-dimensional clusters of molybdenum atoms inside the inner cores of double-walled carbon nanotubes. A combined characterization including high resolution transmission electron microscopy, nitrogen adsorption measurement at 77 K, x-ray photoelectron spectroscopy, Raman spectroscopy, and thermogravimetric analysis reveals that the growth of one-dimensional Mo clusters can be controlled by varying the reaction conditions. The products have specific surface areas of 360–480 m2 g−1360–480 m2 g−1, and their characteristic properties are attributed to the presence of Mo cluster, which affect the electronic structure and can be exploited for the development of nanotube electronic devices.

Crystal Structure of the Homology Domain of the Eukaryotic DNA Replication Proteins Sld3/Treslin

SummaryThe initiation of eukaryotic chromosomal DNA replication requires the formation of an active replicative helicase at the replication origins of chromosomal DNA. Yeast Sld3 and its metazoan counterpart Treslin are the hub proteins mediating protein associations critical for the helicase formation. Here, we show the crystal structure of the central domain of Sld3 that is conserved in Sld3/Treslin family of proteins. The domain consists of two segments with 12 helices and is sufficient to bind to Cdc45, the essential helicase component. The structure model of the Sld3-Cdc45 complex, which is crucial for the formation of the active helicase, is proposed

Coupled K+–Water Flux through the HERG Potassium Channel Measured by an Osmotic Pulse Method

The streaming potential (Vstream) is a signature feature of ion channels in which permeating ions and water molecules move in a single file. Vstream provides a quantitative measure of the ion and water flux (the water–ion coupling ratio), the knowledge of which is a prerequisite for elucidating the mechanisms of ion permeation. We have developed a method to measure Vstream with the whole-cell patch-clamp configuration. A HEK293 cell stably expressing the HERG potassium channel was voltage clamped and exposed to hyperosmotic solutions for short periods of time (<1 s) by an ultrafast solution switching system (the osmotic pulse [quick jump-and-away] method). The reversal potentials were monitored by a series of voltage ramps before, during, and after the osmotic pulse. The shifts of the reversal potentials immediately after the osmotic jump gave Vstream. In symmetrical K+ solutions (10 mM), the Vstreams measured at different osmolalities showed a linear relationship with a slope of −0.7 mV/ΔOsm, from which the water–ion coupling ratio (n, the ratio of the flux of water to the flux of cations; Levitt, D.G., S.R. Elias, and J.M. Hautman. 1978. Biochim. Biophys. Acta. 512:436–451) was calculated to be 1.4. In symmetrical 100 mM K+ solutions, the coupling ratio was decreased significantly (n = 0.9), indicating that the permeation process through states with increased ion occupancy became significant. We presented a diagrammatic representation linking the water–ion coupling ratio to the mode of ion permeation and suggested that the coupling ratio of one may represent the least hydrated ion flux in the single-file pore

Strong and stable photoluminescence from the semiconducting inner tubes within double walled carbon nanotubes

This article may be downloaded for personal use only. Any other use requires prior permission of the author and the American Institute of Physics. The following article appeared in APPLIED PHYSICS LETTERS. 94(8):083106 (2009) and may be found at https://doi.org/10.1063/1.3085966 .ArticleAPPLIED PHYSICS LETTERS. 94(8):083106 (2009)journal articl

Wall-to-wall stress induced in (6,5) semiconducting nanotubes by encapsulation in metallic outer tubes of different diameters: A resonance Raman study of individual C(60)-derived double-wall carbon nanotubes

We measure resonant Raman scattering from 11 individual C(60)-derived double-wall carbon nanotubes all having inner semiconducting (6,5) tubes and various outer metallic tubes. The Raman spectra show the radial breathing modes (RBM) of the inner and the outer tubes to be simultaneously in resonance with the same laser energy. We observe that an increase in the RBM frequency of the inner tubes is related to an increase in the RBM frequency of the outer tubes. The Raman spectra also contain a sharp G(-) feature that increases in frequency as the nominal diameter of the outer metallic tubes decreases. Finally, the one-phonon second-order D-band mode shows a two-way frequency splitting that decreases with decreasing nominal wall-to-wall distance. We suggest that the stress which increases with decreasing nominal wall-to-wall distance is responsible for the hardening that is observed in the frequencies of the RBM, D and G(-) modes of the inner (6,5) semiconducting tubes.ArticleNANOSCALE. 2(3):406-411 (2010)journal articl

Tritium and iodine-129 concentrations in precipitation at Tsukuba, Japan, after the Fukushima Daiichi Nuclear Power Plant accident

The earthquake off the Pacific coast of Japan and the subsequent tsunami on March 11, 2011, triggered a series of accidents in the Fukushima Daiichi Nuclear Power Plant (FNPP1). The accidents caused the release of a mixture of radioactive substances into the environment. This study measured the concentration of tritium (3H) and iodine-129 (129I) in rainwater samples collected at Tsukuba, 170 km southwest of the plant, during the year following the accident. High 3H concentrations were observed in the rainwater samples collected within one month after the FNPP1 accident. 3H concentrations decreased steadily over time and returned to the levels before the accident. Concentrations of 129I also decreased over time. However, pulses of high 129I concentrations were observed at several other times following the accident. The 129I concentrations were found to be correlated with iron concentrations in rainwater. It is likely that iron oxide, which can absorb iodate ions (IO3–), was the carrier of radiogenic iodine. This study concludes that 129I and also 131I, which is one of the most harmful radionuclides produced in nuclear reactors, can be redistributed to the atmosphere in the months following the deposition of radiogenic iodine on the ground

Synthesis of Y2O3 Films by Spray Coating with Milled EDTA ・Y・H Complexes

Yttrium oxide (Y2O3) films have been successfully deposited with yttrium-ethylenediaminetetraacetic acid (EDTA・Y・H) complexes prepared by various milling techniques. The effects of the properties of the EDTA・Y・H complex on the properties of the deposited Y2O3 films have been analyzed. Seven different types of the raw EDTA・Y・H complexes were prepared by various commercial milling techniques such as ball milling, hammer milling, commercial milling, and mortar milling. The milled EDTA・Y・H complexes exhibited various particle sizes and distributions, depending on the milling method. Furthermore, we analyzed the crystal structure, morphology and elemental distribution profile of the metal oxide films deposited on stainless steel substrate with the milled EDTA・Y・H complexes. Depending on the milling technique, the flow properties of the raw powders differed. The X-ray diffraction pattern of all the samples revealed the formation of Y2O3 crystalline phase, irrespective of the milling technique. Of all the different milling techniques, the hammer milling technique is considered suitable for fabricating dense Y2O3 films

Loop formation in graphitic nanoribbon edges using furnace heating or Joule heating

"Here the authors report the use of either furnace heating or Joule heating to pacify the exposed graphene edges by loop formation in a novel graphitic nanoribbon material, grown by chemical vapor deposition. The edge energy minimization process involves the formation of loops between adjacent graphene layers within the nanoribbons. A comparison is made of the similarities and differences between the loop structures formed using these two methods. An estimation of the temperature of these graphitic nanoribbons during Joule heating is also reported based on the melting and evaporation of Pt nanoparticles.

A New Framework of Technology and Engineering Education Proposed by the Japan Society of Technology Education

The Japan Society of Technology Education (JSTE), an academic society for leading technology education research in Japan, has proposed a new framework of technology and engineering education in 2021 to impact the next revision of the Japan's national curriculum. The proposal includes a triple-loop model of the engineering design process and a model of the problem-solving process in line with learners' developmental stages. It also proposes to incorporate the connections between physical and cyber technologies, and between technology and other disciplines in the scope of technology education. However, this proposal was written in Japanese only, is not translated in other language. In this report, we will report of the result of survey conducted in this project, and introduce the contents of the proposal with some practical examples