Redo operation after surgery for aortic aneurysm and dissection

Thirteen patients who underwent redo operation after surgical treatment of aortic aneurysm and dissection were presented. In 8 patients, redo operations were performed for aortic dissection following aortic valve replacement. A-C bypass, the Koster-Collins operation and replacement of thoracic aorta. In the other 5 patients, the reasons for redo operation were aortic root enlargement after replacement of ascending aorta and aortic valve replacement, pseudoaneurysm and aneurysmal dilatation around coronary button for the Bentall operation and recurrent aneurysm after patch aortoplasty and thoracoabdominal replacement using the Crawford's maneuver. To prevent these redo operation, adequate selection of surgical procedures and meticulous operative techniques should be required in primary operation.     

Electrochemical study on hot corrosion of Si-modified aluminide coated In-738LC in Na2SO4-20 wt.% NaCl melt at 750 °C

The corrosion performance of the slurry Si-modified aluminide coating on the nickel base superalloy In-738LC exposed to low temperature hot corrosion condition has been investigated in Na₂SO₄-20 wt.% NaCl melt at 750 °C by combined use of the anodic polarization and characterization techniques.The coated specimen showed a passive behavior up to −0.460 V vs. Ag/AgCl (0.1 mol fraction) reference electrode, followed by a rapid increase in anodic current due to localized attack in the higher potential region. In the passive region, the anodic dissolution of constituents of the coating occurred through the passive film, probably SiO₂, at slow rate of 20-30 μA/cm². The passive current for the Si-modified coating was two orders of magnitude smaller than that for bare In-738LC, which is known as Cr₂O₃ former in this melt. This indicates that the SiO₂ film is chemically more stable than Cr₂O₃ film under this condition. However, pitting-like corrosion commenced around −0.460 V and proceeded at the high rate of 100 mA/cm² in the higher potential region than +0.400 V. The corrosion products formed on the coating polarized in different anodic potentials were characterized by SEM, EDS and XRD. It was found from the characterization that oxidation was dominant attack mode and no considerable sulfidation occurred at 750 °C. The SiO₂ oxide was not characterized in the passive region because the thickness of the passive film was extremely thin, but was detected as the primary oxide in the localized corrosion region, where the selective oxidation of Al was observed by further progress of the corrosion attack front into the inner layer of coating.     

Hydrothermal stability of fluorine-induced microporous silica membranes: Effect of steam treatment conditions

A fluorine-SiO₂ membrane was prepared using triethoxyfluorosilane (TEFS) as a Si precursor, and its hydrothermal stability was evaluated. The TEFS membrane calcined at 750°C had fewer Si-OH and Si-F groups in its network structure and showed H₂ permeance that was greater than 10⁻⁶ mol m⁻² s⁻¹ Pa⁻¹ with H₂/N₂ and N₂/SF₆ permeance ratios of 10 and 210, respectively. This membrane performance was relatively stable under the temperature (< 500°C) used for steam treatment, regardless of the steam partial pressure (30, 90 kPa). On the other hand, when the steam treatment temperature was increased beyond 500°C, gas permeance decreased significantly and the membrane became highly selective for He and H₂ over smaller molecules (He/N₂: > 600, H₂/N₂: > 100). The relationship between the activation energy of H₂ and the permeance ratios (He/H₂, He/H₂O, H₂/H₂O) of a TEFS-derived membrane under steam treatment higher than 600°C resulted in a network pore size that approximated in conventional microporous SiO₂ membranes.     

Functional genomics of commercial baker's yeasts that have different abilities for sugar utilization and high-sucrose tolerance under different sugar conditions

In the modern baking industry, high-sucrose-tolerant (HS) and maltose-utilizing (LS) yeast were developed using breeding techniques and are now used commercially. Sugar utilization and high-sucrose tolerance differ significantly between HS and LS yeasts. We analysed the gene expression profiles of HS and LS yeasts under different sucrose conditions in order to determine their basic physiology. Two-way hierarchical clustering was performed to obtain the overall patterns of gene expression. The clustering clearly showed that the gene expression patterns of LS yeast differed from those of HS yeast. Quality threshold clustering was used to identify the gene clusters containing upregulated genes (cluster 1) and downregulated genes (cluster 2) under high-sucrose conditions. Clusters 1 and 2 contained numerous genes involved in carbon and nitrogen metabolism, respectively. The expression level of the genes involved in the metabolism of glycerol and trehalose, which are known to be osmoprotectants, in LS yeast was higher than that in HS yeast under sucrose concentrations of 5-40%. No clear correlation was found between the expression level of the genes involved in the biosynthesis of the osmoprotectants and the intracellular contents of the osmoprotectants. The present gene expression data were compared with data previously reported in a comprehensive analysis of a gene deletion strain collection. Welch's t-test for this comparison showed that the relative growth rates of the deletion strains whose deletion occurred in genes belonging to cluster 1 were significantly higher than the average growth rates of all deletion strains.     

Cytochrome c-552 from gram-negative alkaliphilic Pseudomonas alcaliphila AL15-21T alters the redox properties at high pH

A soluble class I cytochrome c of an alkaliphile was purified and characterized, and its primary structure was determined. This is the first example of a soluble class I cytochrome c in alkaliphiles. Cells the alkaliphilic gram-negative bacterium Pseudomonas alcaliphila AL15-21(T) grown at pH 10 had a soluble cytochrome c content that was more than twofold that of strain AL15-21(T) cells grown at pH 7 under air-limited conditions. Cytochrome c-552, a soluble cytochrome c with a low molecular weight, was purified from strain AL15-21(T) cells grown at pH 10 under air-limited conditions. Cytochrome c-552 had a molecular mass of 7.5 kDa and exhibited an almost fully reduced state in the resting form, which exhibited absorption maxima at wavelengths of 552, 523 and 417 nm. In the oxidized state, it exhibited an absorption maximum at 412 nm when it was oxidized by ferricyanide, its isoelectric point (pI) was 4.3 and it contained one heme c as a prosthetic group. Cytochrome c-552 was autoreduced at pH 10, and the autoreduction was reproducible. On the other hand, the autoreduction of cytochrome c-552 was not observed at pH 7.0. When pH was increased from 7.0 to 8.3, its midpoint redox potentials (E(m) values) increased from +228 mV to +276 mV as determined by redox titrations, and from +217 mV to +275 mV as determined by cyclic voltammetric measurements. The amino acid sequence deduced by cytochrome c-552 gene analysis revealed that the sequence consists of 96 residues, including 19 residues as an amino-terminal signal peptide. A phylogenetic tree based on amino acid sequence indicated that the protein belongs to group 4, cytochrome c(5) in class I cytochrome c.     

Influence of oxygen transfer in Hf-based high-k dielectrics on flatband voltage shift

We investigated flatband voltage (Vfb) behavior for several Hf-based high-k dielectrics, including HfO₂, Mg-, and La-incorporated HfO₂, HfSiO_x, and Mg-, La-, and N-incorporated HfSiO_x, during the reduction (forming gas annealing: FGA) and oxidation annealing (ODA) processes. A negative Vfb shift appeared in all high-k dielectrics as the FGA temperature increased. In contrast, a positive Vfb shift was observed after the introduction of additional oxygen into the high-k layer during ODA. The oxygen diffusion coefficient (D) values of all samples were estimated using Fick's law. The results showed that the D value of the HfO₂ dielectric was five times as large as that of the HfSiO_x dielectric in ODA at 400 °C. Furthermore, the Mg-, La-, and N- incorporated high-k dielectrics exhibited a larger D value compared with the pure high-k dielectrics. These results strongly suggest that the ionicity of high-k dielectrics, which we attribute to a large positive Vfb shift, enhances oxygen diffusion in the high-k layer.     

Optimal coteries for rings and related networks

Summary Let a distributed system be represented by a graphG=(V, E), whereV is the set of nodes andE is the set of communication links. A coterie is defined as a family,C, of subsets ofV such that any pair of subsets inC has at least one node in common and no subset inC contains any other subset inC. Assuming that each nodev _i V (resp. linke _j E) is operational with probabilityp _i (resp.r _j ), the availability of a coterie is defined as the probability that the operational nodes and links ofG connect all nodes in at least one subset in the coterie. Although it is computationally intractable to find an optimal coterie that maximizes availability for general graphG, we show in this paper that, ifG is a ring, either a singleton coterie or a 3-majority coterie is optimal. Therefore, for any ring, an optimal coterie can be computed in polynomial time. This result is extended to the more general graphs, in which each biconnected component is either an edge or a ring. Toshihide Ibaraki received the B.E., M.E., and Dr. E. degrees from Kyoto University, in 1963, 1965 and 1970, respectively. Since 1969, he has been with the Department of Applied Mathematics and Physics, Kyoto University, except for two and a half years from 1983 to 1985, during which time he was with Department of Computer and Information Sciences, Toyohashi University of Technology. Currently, he is a professor of Kyoto University. He has held a number of visiting appointments with University of Illinois, University of Waterloo, Simon Fraser University, Rutgers University, and others. He is the author of Enumerative Approaches to Combinatorial Optimization, Baltzer AG., a coauthor of Resource Allocation Problems: Algorithmic Approaches, MIT Press, and the author of several books in Japanese, including Algorithms and Data Structures, Shoukohdou. His interest includes algorithms, optimization, computational complexity and their applications. Hiroshi Nagamochi was born in Tokyo, on January 1, 1960. He received the B.A., M.E. and D.E. degrees from Kyoto University, in 1983, in 1985 and in 1988, respectively. From 1988 to 1990, he was with Department of Computer and Information Sciences, Toyohashi University of Technology. Currently, he is an Associate Professor in the Department of Applied Mathematics and Physics at Kyoto University. His research interests include network flow problems and graph connectivity problems. Dr. Nagamochi is a member of the Operations Research Society of Japan and the Information Processing Society. Tsunehiko Kameda received the B.E. and M.E. degrees from the University of Tokyo in 1961 and 1963, respectively, and the Ph.D. degree from Princeton University in 1968. From 1967 to 1980, he was with the Department of Electrical Engineering, University of Waterloo. Since 1981, he has been with Simon Fraser University, Burnaby, British Columbia, Canada, where he is a Professor of Computing Science and is the Director of Computer and Communications Research Laboratory. He has held a number of visiting appointments with Universities of Erlangen-Nürnberg, Bonn, Frankfurt, and Braunschweig, and Gesellschaft für Mathematik und Datenverarbeitung, all in Germany, and also with Kyoto University, Japan. Dr. Kameda is a member of the ACM. He has co-authored three books: Einführung in die Codierungstheorie, Bibliographisches Institut, Distributed Algorithms, Kindai Kagaku-Sha, and A Probabilistic Analysis of Test Response Compaction, IEEE Press. His current research interests include database systems, combinatorial algorithms, distributed computing, ATM networks, and random testing of VLSI circuits.This work was supported in part by Grant-in-Aid from the Ministry of Education, Science and Culture of Japan, and in part by grants from the Natural Sciences and Engineering Research Council of Canada, and the Advanced Systems Institute of British Columbia.     

纯铬钝化膜的电化学性能

本文用交流阻抗技术,通过对钝化铬在中性H₃BO₃+Na₂B₄O₇溶液中添加了K₃Fe₂(CN)₆/K₄Fe(CN)₆氧化还原对溶液中的极化性能及交流阻抗特性的研究,讨论了铬的钝化膜的电路模型。     

3D reconstruction considering calculation time reduction for linear trajectory shooting and accuracy verification with simulator

Artificial Life and Robotics - Photogrammetry is a three-dimensional (3D) reconstruction from images. In photogrammetry, when each image captures the features of the target object for 3D...