β‐1,6‐glucan synthesis‐associated genes are required for proper spore wall formation in Saccharomyces cerevisiae

The yeast spore wall is an excellent model to study the assembly of an extracellular macromolecule structure. In the present study, mutants defective in β ‐1,6‐glucan synthesis, including kre1? , kre6? , kre9? and big1? , were sporulated to analyse the effect of β ‐1,6‐glucan defects on the spore wall. Except for kre6? , these mutant spores were sensitive to treatment with ether, suggesting that the mutations perturb the integrity of the spore wall. Morphologically, the mutant spores were indistinguishable from wild‐type spores. They lacked significant sporulation defects partly because the chitosan layer, which covers the glucan layer, compensated for the damage. The proof for this model was obtained from the effect of the additional deletion of CHS3 that resulted in the absence of the chitosan layer. Among the double mutants, the most severe spore wall deficiency was observed in big1? spores. The majority of the big1?chs3? mutants failed to form visible spores at a higher temperature. Given that the big1? mutation caused a failure to attach a GPI‐anchored reporter, Cwp2‐GFP, to the spore wall, β ‐1,6‐glucan is involved in tethering of GPI‐anchored proteins in the spore wall as well as in the vegetative cell wall. Thus, β ‐1,6‐glucan is required for proper organization of the spore wall. Copyright © 2017 John Wiley & Sons, Ltd.     

Multiscale, Multiphysics Numerical Modeling of Fusion Welding with Experimental Characterization and Validation

Various physical interfacial phenomena occur during the process of welding and influence the final properties of welded structures. As the features of such interfaces depend on physics that resolve at different spatial scales, a multiscale and multiphysics numerical modeling approach is necessary. In a collaborative research project Modeling of Interface Evolution in Advanced Welding, a novel strategy of model linking is employed in a multiscale, multiphysics computational framework for fusion welding. We only directly link numerical models that are on neighboring spatial scales instead of trying to link all submodels directly together through all available spatial scales. This strategy ensures that the numerical models assist one another via smooth data transfer, avoiding the huge difficulty raised by forcing models to attempt communication over many spatial scales. Experimental activities contribute to the modeling work by providing valuable input parameters and validation data. Representative examples of the results of modeling, linking and characterization are presented.     

Measurement of surface dryout near heating surface at high heat fluxes in subcooled pool boiling

The authors have conducted measurements of liquid–vapor behavior in the vicinity of a heating surface for saturated and subcooled pool boiling on an upward-facing copper surface by using a conductance probe method. A previous paper [A. Ono, H. Sakashita, Liquid–vapor structure near heating surface at high heat flux in subcooled pool boiling, Int. J. Heat Mass Transfer 50 (2007) 3481–3489] reported that thicknesses of a liquid rich layer (a so-called macrolayer) forming in subcooled boiling are comparable to or thicker than those formed near the critical heat flux (CHF) in saturated boiling. This paper examines the dryout behavior of the heating surface by utilizing the feature that a thin conductance probe placed very close to the heating surface can detect the formation and dryout of the macrolayer. It was found that the dryout of the macrolayer formed beneath a vapor mass occurs in the latter half of the hovering period of the vapor mass. Two-dimensional measurements conducted at 121 grid points in a 1-mm × 1-mm area at the center of the heating surface showed that the dryout commences at specific areas and spreads over the heating surface as the heat flux approaches the CHF. Furthermore, transient measurements of wall void fractions from nucleate boiling to transition boiling were conducted under the transient heating mode, showing that the wall void fraction has small values (<10%) in the nucleate boiling region, and then steeply increases in the transition boiling region. These findings strongly suggest that the macrolayer dryout model is the most appropriate model of the CHF for saturated and subcooled pool boiling of water on upward facing copper surfaces.     

Temperature measurements near a heating surface at high heat fluxes in subcooled pool boiling

In previous papers (Int J Heat Mass Transfer, 2008;50:3481–3489, 2009;52: 814–821), the authors conducted measurements of liquid–vapor structures in the vicinity of a heating surface for subcooled pool boiling on an upward‐facing copper surface by using a conducting probe method. We reported that the macrolayer dryout model is the most appropriate model of the CHF and that the reason why the CHF increases with increasing subcooling is most likely that a thick macrolayer is able to form beneath large vapor masses and the lowest heat flux of the vapor mass region shifts towards the higher heat flux. To develop a mechanistic model of the CHF for subcooled boiling, therefore, it is necessary to elucidate the effects of local subcooling on boiling behaviors in the vicinity of a heating surface. This paper measured local temperatures close to a heating surface using a micro‐thermocouple at high heat fluxes for water boiling on an upward‐facing surface in the 0 to 40 K range of subcooling. A value for the effective subcooling, defined as the local subcooling during the period while vapor masses are being formed was estimated from the detected bottom peaks of the temperature fluctuations. It was established that the effective subcooling adjacent to the surface remains at considerably lower values than the bulk liquid subcooling. This suggests that, from nucleation to coalescence, the subcooling of a bulk liquid has a smaller effect on the behavior of primary bubbles than the extent of the subcooling would appear to suggest. An empirical correlation of the effective subcooling is proposed to provide a step towards quantitative modeling of the CHF for subcooled boiling. © 2009 Wiley Periodicals, Inc. Heat Trans Asian Res; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/htj.20277     

Characterization of Dynamics in Materials Using Time-Resolved Electron Microscopy Incorporating Electron Counting and Electron Correlation Spectroscopy

Time-resolved electron microscopy incorporating electron counting and electron correlation spectroscopy can be used to quantify the dynamics in materials faster than the shot noise limit of the real-time observation in conventional transmission electron microscopy. An imaging electron beam current, temporally modulated by the dynamics of the specimen, is selected by the aperture in the image plane, and is measured by means of an electron counting technique. Applications of the method to the study of the dynamics of superconducting vortices and to the observation of nanovibrations of materials associated with elastic properties are discussed.     

Association of Ligamentum Flavum Hypertrophy with Adolescent Idiopathic Scoliosis Progression—Comparative Microarray Gene Expression Analysis

The role of the ligamentum flavum (LF) in the pathogenesis of adolescent idiopathic scoliosis (AIS) is not well understood. Using magnetic resonance imaging (MRI), we investigated the degrees of LF hypertrophy in 18 patients without scoliosis and on the convex and concave sides of the apex of the curvature in 22 patients with AIS. Next, gene expression was compared among neutral vertebral LF and LF on the convex and concave sides of the apex of the curvature in patients with AIS. Histological and microarray analyses of the LF were compared among neutral vertebrae (control) and the LF on the apex of the curvatures. The mean area of LF in the without scoliosis, apical concave, and convex with scoliosis groups was 10.5, 13.5, and 20.3 mm², respectively. There were significant differences among the three groups (p < 0.05). Histological analysis showed that the ratio of fibers (Collagen/Elastic) was significantly increased on the convex side compared to the concave side (p < 0.05). Microarray analysis showed that ERC2 and MAFB showed significantly increased gene expression on the convex side compared with those of the concave side and the neutral vertebral LF cells. These genes were significantly associated with increased expression of collagen by LF cells (p < 0.05). LF hypertrophy was identified in scoliosis patients, and the convex side was significantly more hypertrophic than that of the concave side. ERC2 and MAFB genes were associated with LF hypertrophy in patients with AIS. These phenomena are likely to be associated with the progression of scoliosis.     

Algicidal effect of bacterial isolates of Pedobacter sp. against cyanobacterium Microcystis aeruginosa

The aim of this study was to isolate algicidal bacteria so as to control harmful cyanobacterium Microcystis aeruginosa (M.aeruginosa) blooms using biological methods. Nine bacterial strains were isolated to inhibit the growth of M. aeruginosa, among which the MaI11-5 bacterial strain exhibited remarkable algicidal activity against M. aeruginosa cells during the test. Based on the 16S rDNA analysis, the isolated MaI11-5 was identified as Pedobacter sp. through morphology and homology research. The results of cocultivation of the cyanobacteria with MaI11-5 algicidal isolates showed obvious algicidal activity against cyanobacterial cells. The algicidal effect of MaI11-5 exceeded 50% after two days, exceeded 70% after four days, and reached 80% after seven days. The observation results with a scanning electron microscope showed that the cyanobacterial cells aggregated and produced mucous-like substances when cocultivated with the algicidal bacteria. The results indicated that the MaI11-5 bacterial strain may possess a novel function for controlling harmful blooms and further studies will provide new insights into its role in water environment.     

A novel beta-galactoside-binding lectin in cultured murine lymphocytic leukemia cells

Using affinity chromatography on lactosyl-Sepharose, a beta-galactoside-binding protein of 38 kDa was detected in mouse L1210 lymphocytic leukemia cells. Immunoblotting analysis revealed that it is distinct from any known larger molecular weight galectin. The partial amino acid sequences of the 38 kDa protein indicated that it is a novel member of the galectin family. This 38 kDa lectin is expressed in lymphocytic cell lines but not macrophage-like cell lines.