Development of Nanostructured Tungsten Based Materials Resistant to Recrystallization and/or Radiation Induced Embrittlement

Mitigation of embrittlement caused by recrystallization and radiation is the key issue of tungsten (W) based materials for use in the advanced nuclear system such as fusion reactor applications. In this paper, our nanostructured W materials development performed so far to solve the key issue is reviewed, including new original data. Firstly, the basic concept of mitigation of the embrittlement is shown. The approach to the concept has yielded ultra-fine grained, recrystallized (UFGR) W–(0.25–1.5) mass%TiC compacts containing fine TiC dispersoids (precipitates). The UFGR W–(0.25–1.5)%TiC exhibits favorable as well as unfavorable features from the viewpoints of microstructures and various thermo-mechanical properties including the response to neutron and ion irradiations. Most of the unfavorable features stem from insufficient strengthening of weak random grain boundaries (GBs) in the recrystallized state. The focal point on this study is, therefore, to develop a new microstructural modification method to significantly strengthen the random GBs. The method is designated as GSMM (GB Sliding-based Microstructural Modification) and has lead to the birth of toughened, fine-grained W–1.1%TiC in the recrystallized state (TFGR W–1.1TiC). The TFGR W–1.1TiC exhibits much improved thermo-mechanical properties. The applicability of TFGR W–1.1TiC to the divertor in ITER is discussed

Plasma Membrane and Nuclear Localization of G Protein–coupled Receptor Kinase 6A

G protein–coupled receptor (GPCR) kinases (GRKs) specifically phosphorylate agonist-occupied GPCRs at the inner surface of the plasma membrane (PM), leading to receptor desensitization. Here we show that the C-terminal 30 amino acids of GRK6A contain multiple elements that either promote or inhibit PM localization. Disruption of palmitoylation by individual mutation of cysteine 561, 562, or 565 or treatment of cells with 2-bromopalmitate shifts GRK6A from the PM to both the cytoplasm and nucleus. Likewise, disruption of the hydrophobic nature of a predicted amphipathic helix by mutation of two leucines to alanines at positions 551 and 552 causes a loss of PM localization. Moreover, acidic amino acids in the C-terminus appear to negatively regulate PM localization; mutational replacement of several acidic residues with neutral or basic residues rescues PM localization of a palmitoylation-defective GRK6A. Last, we characterize the novel nuclear localization, showing that nuclear export of nonpalmitoylated GRK6A is sensitive to leptomycin B and that GRK6A contains a potential nuclear localization signal. Our results suggest that the C-terminus of GRK6A contains a novel electrostatic palmitoyl switch in which acidic residues weaken the membrane-binding strength of the amphipathic helix, thus allowing changes in palmitoylation to regulate PM versus cytoplasmic/nuclear localization

RSBP-1 Is a Membrane-targeting Subunit Required by the Gαq-specific But Not the Gαo-specific R7 Regulator of G protein Signaling in Caenorhabditis elegans

In vivo characterization of the C. elegans R7 RGS Binding Protein, RSBP-1, shows that this protein is required to target the Gαq-specific, but not the Gαo-specific, R7 RGS protein to the plasma membrane, that plasma membrane localization is essential for function, and suggests that the mechanism of membrane targeting may determine Gα specificity

Ric-8 controls Drosophila neural progenitor asymmetric division by regulating heterotrimeric G proteins

10.1038/ncb1317Nature Cell Biology7111091-1098NCBI