Plasticity initiation and subsequent deformation behavior in the vicinity of single grain boundary investigated through nanoindentation technique

The initiation of plasticity and the subsequent state in the vicinity of a single grain boundary during indentation-induced deformation were investigated to understand an elementary step of a stress-strain behavior of polycrystalline materials. Nanoindentation measurements on several points on a single grain boundary and the grain interior of an interstitial-free steel and an analysis on the pop-in behavior and the plastic nanohardness were carried out. The pop-in load P ^c that was obtained on the loading curve is different for each measurement. However, the loading curves overlap one another and the unloading curves coincide as well after the pop-in event. The nanohardness Hn has no dependence on the P ^c in the range of 150–550 μN. The relation between P ^c and Δh can be expressed as a simple cubic polynomial function based on a geometrically necessary dislocation loop model. The fitted function differed for various grains with different crystallographic orientations.     

Measurement and numerical simulation of a small centrifugal compressor characteristics at small or negative flow rate

For centrifugal compressors used in automotive turbochargers,the extension of the surge margin is demanded because of lower engine speed.In order to estimate the surge line exactly,it is required to acquire the compressor characteristics at small or negative flow rate.In this paper,measurement and numerical simulation of the characteristics at small or negative flow rate are carried out.In the measurement,an experimental facility with a valve immediately downstream of the compressor is used to suppress the surge.In the numerical work,a new boundary condition that specifies mass flow rate at the outlet boundary is used to simulate the characteristics around the zero flow rate region.Furthermore,flow field analyses at small or negative flow rate are performed with the numerical results.The separated and re-circulated flow fields are investigated by visualization to identify the origin of losses.     

Surface Modification of Epoxy Resin with Silicone-containing Block Copolymers

In order to improve oil and water repellency, silicone-containing block copolymers, composed of methylmethacrylate (MMA), glycidylmethacrylate (GMA), and polydimethylsiloxanemethacrylate (SMA), were blended in an epoxy resin. It was expected that the low surface energy dimethylsiloxane segments would adsorb and orient at the exterior of the resin to make a thin surface phase and the glycidyl groups would mesh with the epoxy resin by primary bonding. The techniques of X-ray photoelectron spectroscopy (ESCA), dynamic contact angle (DCA) and peel strength measurements of pressure sensitive adhesives were used to characterize the modified epoxy resin surface phases. The amount of Si_2p obtained via angular dependent ESCA investigation in the near surface region of the modified resin increased with decreasing sampling depth. With an increase in modifier content, both the amount of Si_2p and O_1s also increased. Both advancing and receding contact angles for an aluminum plate coated with modified resin, measured by dipping into and out of water, increased with the addition of these modifiers. The peel strength of a pressure sensitive adhesive tape affixed to the modified epoxy resin decreased dramatically with increasing modifier content. It was found that these copolymers were good surface modifiers to improve oil and water repellency and that they acted as release agents.     

PAD1 and FDC1 are essential for the decarboxylation of phenylacrylic acids in Saccharomyces cerevisiae

The volatile phenols, to which Saccharomyces cerevisiae converts from phenylacrylic acids including ferulic acid, p-coumaric acid, and cinnamic acid, generate off-flavors in alcoholic beverages such as beer and wine. Using gene disruptants, transformants and cell-free extracts of these strains, we have verified that the adjacent PAD1 (phenylacrylic acid decarboxylase, YDR538W) and FDC1 (ferulic acid decarboxylase, YDR539W) genes are essential for the decarboxylation of phenylacrylic acids in S. cerevisiae. Pad1p and Fdc1p are homologous with UbiX and UbiD, respectively, in the ubiquinone synthetic pathway of Escherichia coli. However, ubiquinone was detected quantitatively in all of the yeast single-deletion mutants, Δpad1, Δfdc1, and double-deletion mutant, Δpad1Δfdc1.     

Development of a novel hydrate-based refrigeration system: A preliminary overview

This paper gives a preliminary overview of our attempt at developing a hydrate-based refrigeration system based on a novel conceptual design. The system forms a closed cycle, which is more or less analogous to the conventional vapor-compression refrigeration cycle. The cycle of present interest is performed by a multiphase refrigerant, which is typically a mixture of one or two hydrate-forming substances and water. The refrigerant is required to form a hydrate at a temperature as high as 30 °C or above, desirably under a modest pressure, such that the heat released by the exothermic hydrate formation can be efficiently removed by an environmental fluid such as the atmospheric air, groundwater or river water. The hydrate slurry thus formed is depressurized to dissociate at a lower temperature, typically 5–9 °C, thereby absorbing heat from a space to be refrigerated. To confirm the feasibility of the above conceptual design of the hydrate-based refrigeration system, a thermodynamic analysis of the system and a simulation of its operation have been performed. Also a laboratory-scale refrigerator based on the above design was constructed and tested. The paper summarizes the results of these efforts to show the potential advantages of the hydrate-based refrigeration system over conventional ones and to give the prospects of our refrigeration-system development.     

Genes and Gene Networks Involved in Sodium Fluoride-Elicited Cell Death Accompanying Endoplasmic Reticulum Stress in Oral Epithelial Cells

Here, to understand the molecular mechanisms underlying cell death induced by sodium fluoride (NaF), we analyzed gene expression patterns in rat oral epithelial ROE2 cells exposed to NaF using global-scale microarrays and bioinformatics tools. A relatively high concentration of NaF (2 mM) induced cell death concomitant with decreases in mitochondrial membrane potential, chromatin condensation and caspase-3 activation. Using 980 probe sets, we identified 432 up-regulated and 548 down-regulated genes, that were differentially expressed by >2.5-fold in the cells treated with 2 mM of NaF and categorized them into 4 groups by K-means clustering. Ingenuity^® pathway analysis revealed several gene networks from gene clusters. The gene networks Up-I and Up-II included many up-regulated genes that were mainly associated with the biological function of induction or prevention of cell death, respectively, such as Atf3, Ddit3 and Fos (for Up-I) and Atf4 and Hspa5 (for Up-II). Interestingly, knockdown of Ddit3 and Hspa5 significantly increased and decreased the number of viable cells, respectively. Moreover, several endoplasmic reticulum (ER) stress-related genes including, Ddit3, Atf4 and Hapa5, were observed in these gene networks. These findings will provide further insight into the molecular mechanisms of NaF-induced cell death accompanying ER stress in oral epithelial cells.