Bratescu M.A.,EcoTopia Science Institute |
Takai O.,Kanto Gakuin University |
Saito N.,Nagoya University
Journal of Alloys and Compounds | Year: 2013
A rapid, one-step process for the synthesis of bimetallic nanoparticles by simultaneous metal reduction and gold erosion in an aqueous solution discharge was investigated. Gold bimetallic nanoparticles were obtained by alloying gold with various types of metals belonging to one of the following categories: divalent sp metals, trivalent sp metals, 3d or 4d metals. The composition of the various gold bimetallic nanoparticles obtained depends on electrochemical factors, charge transfer between gold and other metal, and initial concentration of metal in solution. Transmission electron microscopy and energy dispersive spectroscopy show that the gold bimetallic nanoparticles were of mixed pattern, with sizes of between 5 and 20 nm. A red-shift of the surface plasmon resonance band in the case of the bimetallic nanoparticles Au-Fe, Au-Ga, and Au-In, and a blue-shift of the plasmon band of the Au-Ag nanoparticles was observed. In addition, the interaction of gold bimetallic nanoparticles with unpaired electrons, provided by a stable free radical molecule, was highest for those NPs obtained by alloying gold with a 3d metal. © 2013 Elsevier B.V. All rights reserved.
Yoshida H.,Kanto Gakuin University |
Sugai T.,University of Tokyo |
Ohmori H.,University of Tokyo
Geomorphology | Year: 2012
Catastrophic collapse of volcanic edifices and the accompanying rockslide-debris avalanches drastically change landforms and cause disasters around volcanoes. Rapid modification of the landforms created by these events makes it difficult to estimate the magnitudes of prehistoric events and evaluate damage. However, the widespread preservation of hummocks along the course of rockslide-debris avalanches is useful for understanding the physical characteristics of these landslides. We analyzed data on hummocks from seven prehistoric events in northern Japan to derive the relationship between hummock size and distance from landslide source, and interpreted the geomorphic significance of the intercept and slope coefficients of the observed functional relationships. Hummock size decreases as an exponential function of distance for volcanic rockslide-debris avalanches, although each event has its own distinct distribution pattern. The intercept coefficient, α, which corresponds to the initial average size of hummocks (blocks) at the origin of the landslide, shows a strong correlation with the volume of the collapsed mass, indicating that the initial size of blocks at the source may be determined by the volume of the collapsed mass. The slope coefficient, β, which describes the rate of decrease in size of hummocks with distance, shows a strong correlation with the coefficient of friction of the rockslide-debris avalanche, indicating that the attrition or size decrease rate of hummocks is controlled by the mobility of the avalanche. These relationships enable us to estimate the volume of the collapsed mass and the travel distance of an avalanche. Because it is sometimes difficult to obtain the evidence directly indicating the volume of collapses and the damage they caused, the findings are significant also for hazard assessment that the size-distance relationships of hummocks can be obtained from fragmentary remnants of a rockslide-debris avalanche to help reveal the characteristics of the events. © 2011 Elsevier B.V.
Momose-Sato Y.,Kanto Gakuin University |
Sato K.,Komazawa Womens University
Respiratory Physiology and Neurobiology | Year: 2011
To regulate the autonomic function, the vagus nerve transfers various sensory information from peripheral organs, and appropriate motor reflexes are produced in the neural circuit. The functional development of the vagal pathway during the early phase of embryonic development has long been unclear. Optical recording with voltage-sensitive dyes has provided a new approach to the analysis of the functional development of the embryonic central nervous system. In this review, we present recent progress in optical studies on the vagal pathway in the embryonic chick and rat brainstems. The topics include how neural excitability is initially expressed in the motor and sensory nuclei [e.g. the dorsal motor nucleus of the vagus nerve (DMNV) and the nucleus of the tractus solitarius (NTS)] and how synapse networks are formed in the primary and higher-ordered sensory nuclei [e.g. the parabrachial nucleus (PBN)]. We also refer to the functional development of the glossopharyngeal nuclei and compare the developmental steps with those of the vagal nuclei. © 2011 Elsevier B.V.
Yamada T.,Kanto Gakuin University |
Funaki Y.,University of Tsukuba
Physical Review C - Nuclear Physics | Year: 2010
The structure of 3/2⊃- and 1/2⊃+ states in B11 is investigated with an α+α+t orthogonality condition model (OCM) based on the Gaussian expansion method. Full levels up to the 3/23- and 1/22+ states around the α+α+t threshold (Ex=11.1 MeV) are reproduced consistently with the experimental energy levels. It is shown that the 3/23- state located around the 7Li+α threshold has an α+α+t cluster structure, whereas the 3/21- and 3/22- states have a shell-model-like compact structure. We found that the 3/23- state does not possess an α-condensate-like nature analogous to the 02+ state of C12 (Hoyle state) which has a dilute 3α-condensate structure described by a (0Sα)3 configuration with about 70% probability, although the monopole transition strength of the former is as large as that of the latter. We discuss the reasons why the 3/23- state does not have the condensate character. On the other hand, the 1/21+ state just below the 7Li+α threshold has a cluster structure that can be interpreted as a parity-doublet partner of the 3/23- state. We indicate that the 12.56-MeV state (Jπ=1/22+) just above the α+α+t threshold observed in the Li7(Li7,B11⊃*)t reaction, etc., is of the dilute cluster-gas-like configuration and is a strong candidate for the product states of clusters, having a configuration of (0Sα)2(0S t) with about 65% probability, from the analyses of the single-cluster motions in B11. The structure property of the 1/2⊃+ resonant state is analyzed with the complex scaling method. © 2010 The American Physical Society.
Momose-Sato Y.,Kanto Gakuin University |
Sato K.,Komazawa Womens University
Neuroscience Letters | Year: 2014
We examined the initial expression of synaptic function in the embryonic chick trigeminal nucleus using voltage-sensitive dye recording. Brainstem preparations with three trigeminal nerve afferents, the ophthalmic nerve (N.V1), maxillary nerve (N.V2) and mandibular nerve (N.V3), were dissected from 5.5- to 6.5-day-old chick embryos. In our previous study [Sato et al., 1999], we detected slow signals corresponding to glutamatergic excitatory postsynaptic potentials and identified the principal sensory nucleus of the trigeminal nerve (Pr5), spinal sensory nucleus of the trigeminal nerve (Sp5) and trigeminal motor nucleus. In this study, we examined the effects of removing Mg2+ from the physiological solution, which enhanced N-methyl-d-aspartate receptor function in the sensory nuclei. In 6.5-day-old (St 29) embryos, the slow signal was observed in Pr5 and Sp5 only when N.V1 was stimulated, whereas it appeared in Mg2+-free solution with every nerve stimulation. In 6-day-old (St 28) embryos, the slow signal was observed in Sp5 with N.V1 stimulation, and the appearance of synaptic function in Mg2+-free solution varied, depending on the nerves and preparations used. In 5.5-day-old (St 27) embryos, synaptic function was not detected even when external Mg2+ was removed. These results indicate that the initial expression of synaptic function in the trigeminal system occurs earlier than previously considered, and that the developmental organization of synaptic function differs among the three trigeminal nerves and between the two sensory nuclei. © 2014 Elsevier Ireland Ltd.