Surface cracking on Σ3, Σ9 CSL and random grain boundaries in helium implanted 316L austenitic stainless steel

The relationship between surface cracking at grain boundaries and the grain boundary nature in helium implanted 316L austenitic stainless steel was investigated by in situ annealing in a high-voltage electron microscope, and by SEM and TEM observations. The nucleation and growth of helium bubbles at a random grain boundary was observed during annealing up to 973 K. After annealing, surface cracking was observed at the random grain boundaries and some coincidence site lattice (CSL) boundaries because of the formation and rupture of the helium bubbles at these grain boundaries. At the faceted CSL boundaries, surface cracking occurred only on one boundary facet plane. This indicates that the twin boundary and pure tilt Σ9 CSL boundary show the highest resistance to cracking because of their low boundary energies.     

Tea catechins modulate the glucose transport system in 3T3-L1 adipocytes

In this study, we investigated the effects of tea catechins on the translocation of glucose transporter (GLUT) 4 in 3T3-L1 adipocytes. We found that the ethyl acetate fraction of green tea extract, containing abundant catechins, most decreased insulin-induced glucose uptake activity in 3T3-L1 cells. When the cells were treated with 50 μM catechins in the absence or presence of insulin for 30 min, nongallate-type catechins increased glucose uptake activity without insulin, whereas gallate-type catechins decreased insulin-induced glucose uptake activity. (-)-Epicatechin (EC) and (-)-epigallocatechin (EGC), nongallate-type catechins, increased glucose uptake activity in the dose- and time-dependent manner, whereas (-)-catechin 3-gallate (Cg) and (-)-epigallocatechin 3-gallate (EGCg), gallate-type catechins, decreased insulin-induced glucose uptake activity in the dose- and time-dependent manner. When the cells were treated with 50 μM catechins for 30 min, EC and EGC promoted GLUT4 translocation, whereas Cg and EGCg decreased the insulin-induced translocation in the cells. EC and EGC increased phosphorylation of PKCλ/ζ without phosphorylation of insulin receptor (IR) and Akt. Wortmannin and LY294002, inhibitors for phosphatidylinositol 3'-kinase (PI3K), decreased EC- and EGC-induced glucose uptake activity in the cells. Cg and EGCg decreased phosphorylation of PKCλ/ζ in the presence of insulin without affecting insulin-induced phosphorylation of IR, and Akt. Therefore, EC and EGC promote the translocation of GLUT4 through activation of PI3K, and Cg and EGCg inhibit insulin-induced translocation of GLUT4 by the insulin signaling pathway in 3T3-L1 cells.     

The Quiescent Cellular State is Arf/p53-Dependent and Associated with H2AX Downregulation and Genome Stability

Cancer is a disease associated with genomic instability and mutations. Excluding some tumors with specific chromosomal translocations, most cancers that develop at an advanced age are characterized by either chromosomal or microsatellite instability. However, it is still unclear how genomic instability and mutations are generated during the process of cellular transformation and how the development of genomic instability contributes to cellular transformation. Recent studies of cellular regulation and tetraploidy development have provided insights into the factors triggering cellular transformation and the regulatory mechanisms that protect chromosomes from genomic instability.     

Diffusion of titanium in copper

Interdiffusion coefficients in copper-titanium alloys have been determined by Matano's method in the temperature range between 973 and 1283 K on (pure Cu)-(Cu-1.98 at. pct Ti alloy) and (pure Cu)-(Cu-2.91 at. pct Ti alloy) couples. Temperature dependence of the impurity diffusion coefficient of titanium in copper, determined by extrapolation of the concentration dependence of the interdiffusion coefficient to zero mole fraction of titanium, is expressed by the following Arrhenius equation along with the probable errors:D _Ti/Cu=(0.693 _−0.135 ^+0.169 )×10⁻⁴exp[−(196±2)kJ mol⁻¹/RT] m²/s. The difference in the activation energies for the impurity diffusion of the 3d-transition metals and self-diffusion in copper has been calculated by applying LeClaire's model with the oscillating potential of the impurity atom in copper. The calculated values agree well with the experimental values including the present one. Kazutomo Hoshino, formerly Graduate Student, Tohoku University     

Photonic transport technologies to create robust backbone networks

This article discusses the role of the new optical layer in terms of transport layer architecture and functional allocations. The envisaged future photonic network is identified, and the technologies needed to realize reliable communication are clarified. Network-node interface technologies, and network protection and restoration strategies are discussed in detail, since these are key to developing a network with high integrity that will be a main pillar of the future information society. Finally, applications of photonic network technologies and a network design example are presented; the IP backbone network based on optical path technologies is highlighted     

Increased activity of oleate-dependent type phospholipase D during actinomycin D-induced apoptosis in Jurkat T cells

Apoptosis is an active form of cell death that can be induced by a wide variety of agents and conditions. In response to actinomycin D, hydrogen peroxide (H2O2), or TNF-alpha, Jurkat T cells underwent typical apoptosis. Phospholipase D (PLD) activity in intact cells determined by phosphatidylbutanol generation was up-regulated by these agents. The PLD activation was in a time-dependent manner during apoptosis. It was also shown that the PLD activity measured by using exogenous substrate in the lysate from apoptotic cells was higher than that in the lysate from control untreated cells. The PLD activity in lysate from control untreated cells was stimulated by unsaturated fatty acids (UFA), but not by guanosine 5'-O-(3-thiotriphosphate). However, the PLD activity in the apoptotic cell lysate was no longer enhanced by the addition of oleate, suggesting that the increased PLD activity during apoptosis was attributed to the PLD of UFA-dependent type, but not the small G protein-dependent one. In fact, the release of free UFA was increased during apoptosis. The caspase inhibitors, z-DEVD and z-VAD, effectively suppressed PLD activation and apoptosis, but UFA release was unaffected. These results suggest the possibility that UFA-dependent type PLD may be implicated in apoptotic process in Jurkat T cells. This is the first demonstration that the PLD of UFA-dependent type would be involved in cellular responses.     

Optical signal processing using photorefractive effect

Novel applications of photorefractive effect to optical signal processing are proposed and demonstrated. The applications of two-wave mixing (2-WM) in a bulk photorefractive crystal include logic operations and cross connect. Photorefractive crystal waveguide (PCW) is another primary concern. Holographic storage of Fourier transformed image in PCW and its application to optical neural network, two-dimensional array of PCW as a storage device, phase conjugate mirror using PCW, and structural consideration of PCW for efficient 2-WM are investigated. In the experiments,LiNbO ₃ andBaTiO ₃ waveguides are used.BaTiO ₃ waveguide will be tested here for the first time. In a long-term prospect, all these technologies will eventually find important roles in optical signal processing.     

Shock-Compaction of Nano-Sized Diamond Powder, as Examined by Microstructural Analysis

Nano-sized diamond powder, shock-compacted in the present study, showed neither grain growth nor graphitization, but the compact was fragmented and not strongly consolidated. In contrast, a mixture of the nano-sized powder and submicrometer-sized diamond powder consolidated into a disk with 93 % of theoretical density and a Vickers micro-hardness of 25 GPa also exhibited no grain growth and showed interparticle bonds only among large particles. Although the samples obtained were neither hard nor strong, microstructural analyses and considerations based on the shock-compaction theories and models clarified issues surrounding the shock-compaction method of producing nanocrystalline materials. Both the propriety and the limitation of these theories and models are discussed in this paper.