34 research outputs found
Redox characteristics variations in the cation-ordered perovskite oxides BaLnMn(2)O(5+delta) (Ln = Y, Gd, Nd, and La) and Ca2Al1-xGaxMnO5+delta (0 <= x <= 1)
No full textTwo series of manganese-based oxygen storage materials, BaLnMn(2)O(5+delta) (Ln = Y, Gd, Nd, and La) and Ca2Al1-xGaxMnO5+delta (0 <= x <= 1), were synthesized and characterized to clarify cationic substitution effects on the oxygen intake/release behaviors of these materials. The thermogravimetric data revealed that the isovalent substitutions neighboring the active sites for oxygen intake/release are very effective. For BaLnMn(2)O(5+)delta, fully-reduced delta approximate to 0 products with larger Ln ions showed oxygen intake starting at lower temperatures in flowing O-2 gas, resulting in a systematic relationship between the onset temperature and the ionic radius of Ln(3+). Furthermore, the delta vs. P(O-2) plots at 700 degrees C indicated a systematic trend: the larger the ionic size of Ln(3+) is, the larger oxygen contents the Ln-products exhibit. For Ca2Al1-x-GaxMnO5+delta , on the other hand, the temperature-induced oxygen intake/release characteristics appeared to be influenced by Ga-for-Al substitution, where the onset temperatures of oxygen release (upon heating) and oxygen intake (upon cooling) are decreased with the increasing Ga content (x)
Linear Analysis of Dispersive Waves in Bubbly Flows Based on Averaged Equations
No full textOne-dimensional linear dispersive waves in water flows containing a number of small spherical air bubbles are analytically studied on the basis of a set of averaged equations recently derived by the present authors. The set of equations consists of the conservation laws for gas and liquid phases and the equation of motion of bubble wall. In addition to the volume-averaged pressure in each phase, the surface-averaged liquid pressure at the bubble wall is incorporated. The compressibility of water is taken into account as well as that of gas in bubbles, and a model of virtual mass force is included, although the Reynolds stress, viscosity, heat conductivity, and the phase change across the bubble wall are disregarded. The results are summarized as follows: (i) the waves are decomposed into the fast mode, slow mode, and convection mode (void wave). (ii) In the uniform flows, the three modes stably exist for all real wave numbers. (iii) In the limit of infinitesimal void fraction, the explicit representation of the elementary solution is obtained. (iv) The instability does not appear in the range where the present averaged equations are applicable
Semantic web link analysis to discover social relationship in academic communities
No full textTo discover how precisely links among researchers’ Web sites capture the ties of academic communities, this study conducts Web citation analysis. 3,878 Web sites of computer scientists and their 8,811 articles are assessed. 200 most frequently cited researchers from them are subjected to Web author cocitation analysis and compared to bibliographical data. As a result, a cluster of researchers on the Web becomes a superset of bibliographical one, that is, a community representing a larger research field. We then develop Web link ontology that defines various relationships among researchers to apply metadata annotation to the links among 200 sites. Findings: 1) since intellectual ties analysis separates off sociocognitive ties, it results into a better approximation of bibliographical author cocitation, 2) since sociocognitive ties analysis can utilize various links not only coauthor networks, diverse kinds of social connections can be found, 3) merging intellectual ties and sociocognitive ties analyses detect gatekeepers who bridges research fields on social networks. 1
Redox characteristics variations in the cation-ordered perovskite oxides BaLnMn(2)O(5+delta) (Ln = Y, Gd, Nd, and La) and Ca2Al1-xGaxMnO5+delta (0 <= x <= 1)
No full text
The estimation of concentration fluctuations in liquid Ag-Si and Au-Si alloys
No full textThe specific electrical resistivity was measured for liquid states of Ag–Si and Au–Si with deep eutectic points for which the ‘electron atom ratio’ at the eutectic composition is 1.33 and 1.56, respectively. On lowering the temperature, the specific electrical resistivity deviates from the straight line, which was obtained by extrapolating its behavior from high to low temperatures. The concentration dependence of this deviation at the liquidus shows the largest value at the eutectic composition. The analysis based on the effective medium theory tells us that the volume fraction of concentration fluctuation in the homogeneous liquid phase is largest at the eutectic composition. The degree of concentration fluctuation was summarized on one systematic trend among metal–semiconductor eutectic systems. It is concluded that the large concentration fluctuation develops in the homogeneous liquid phase of eutectic systems. The possibility of the poor supercooling tendency of homogeneous liquids at the eutectic composition was revealed with relation to this concentration fluctuation
Structural Change in Lipid Bilayers and Water Penetration Induced by Shock Waves: Molecular Dynamics Simulations
No full textThe structural change of a phospholipid bilayer in water under the action of a shock wave is numerically studied with unsteady nonequilibrium molecular dynamics simulations. The action of shock waves is modeled by the momentum change of water molecules, and thereby we demonstrate that the resulting collapse and rebound of the bilayer are followed by the penetration of water molecules into the hydrophobic region of the bilayer. The high-speed phenomenon that occurs during the collapse and rebound of the bilayer is analyzed in detail, particularly focusing on the change of bilayer thickness, the acyl chain bend angles, the lateral fluidity of lipid molecules, and the penetration rate of water molecules. The result shows that the high-speed phenomenon can be divided into two stages: in the first stage the thickness of bilayer and the order parameter are rapidly reduced, and then in the second stage they are recovered relatively slowly. It is in the second stage that water molecules are steadily introduced into the hydrophobic region. The penetration of water molecules is enhanced by the shock wave impulse and this qualitatively agrees with a recent experimental result
Changes in the fluctuation of the contraction rhythm of spontaneously beating cardiac myocytes in cultures with and without cardiac fibroblasts.
No full textThe heart functions as a syncytium of cardiac myocytes and surrounding supportive non-myocytes such as fibroblasts. There is a possibility that a variety of non-myocyte-derived factors affect the maturation of cardiac myocytes in the development of the heart. Cultured neonatal cardiac myocytes contract spontaneously and cyclically. The fluctuation of beating rhythm varies depending on the strength of coupling through gap junctions among cardiac myocytes, indicating that the development of intercellular communication via gap junctions is crucial to the stability of contraction rhythm in cardiac myocytes. In this study, we aimed at elucidating whether and how cardiac fibroblasts affect the development of cardiac myocytes from the point of view of the changes in the fluctuation of the contraction rhythm of cardiac myocytes in cardiac myocyte-fibroblast co-cultures. The present study suggested that cardiac fibroblasts co-cultured with cardiac myocytes enhanced the intercellular communication among myocytes via gap junctions, thereby stabilizing the spontaneous contraction rhythm of cultured cardiac myocytes
Phospholipid Flippases Lem3p-Dnf1p and Lem3p-Dnf2p Are Involved in the Sorting of the Tryptophan Permease Tat2p in Yeast
No full textThe type 4 P-type ATPases are flippases that generate phospholipid asymmetry in membranes. In budding yeast, heteromeric flippases, including Lem3p-Dnf1p and -Dnf2p translocate phospholipids to the cytoplasmic leaflet of membranes. Here we report that Lem3p-Dnf1/2p are involved in transport of the tryptophan permease Tat2p to the plasma membrane. The lem3Δ mutant exhibited a tryptophan requirement due to the mislocalization of Tat2p to intracellular membranes. Tat2p was relocalized to the plasma membrane when trans-Golgi network (TGN)-to-endosome transport was inhibited. Inhibition of ubiquitination by mutations in ubiquitination machinery also rerouted Tat2p to the plasma membrane. Lem3p-Dnf1/2p are localized to endosomal/TGN membranes in addition to the plasma membrane. Endocytosis mutants, in which Lem3p-Dnf1/2p are sequestered to the plasma membrane. Endocytosis mutants, in which Lem3p-Dnf1/2p are sequestered to the plasma membrane, also exhibited the ubiquitination-dependent missorting of Tat2p. These results suggest that Tat2p is ubiquitinated at the TGN and missorted to the vacuolar pathway in the lem3Δ mutant. The NH2-terminal cytoplasmic region of Tat2p containing ubiquitination acceptor lysines interacted with liposomes containing acidic phospholipids, including phosphatidylserine. This interaction was abrogated by alanine substitution mutations in the basic amino acids downstream of the ubiquitination sites. Interestingly, a mutant Tat2p containing these substitutions was missorted in a ubiquitination-dependent manner. We propose the following model based on these results; Tat2p is not ubiquitinated when the NH2-terminal region is bound to membrane phospholipids, but if it dissociates from the membrane due to a low level of phosphatidylserine caused by perturbation of phospholipid asymmetry in the lem3Δ mutant, Tat2p is ubiquitinated and then transported from the TGN to the vacuole
