In order to assimilate iron, Acinetobacter baumannii ATCC 19606T produces a siderophore named acinetobactin (Ab) that is composed of equimolar quantities of 2,3-dihydroxybenzoic acid (DHBA), L-threonine and N-hydroxyhistamine. Application of the Fur titration assay system to A. baumannii genomic libraries, followed by further cloning of the regions surrounding the candidate genes, led to the identification of the Ab cluster, which harbours the genetic determinants necessary for the biosynthesis and transport of the siderophore. However, an entA homologue essential for DHBA biosynthesis was not found in this cluster. Functions of potential biosynthetic genes inferred by homology studies suggested that the precursors, DHBA, L-threonine and N-hydroxyhistamine, are linked in steps resembling those of bacterial non-ribosomal peptide synthesis to form Ab. Genes responsible for the two-step biosynthesis of N-hydroxyhistamine from histidine were also identified in this cluster. Their genetic organization suggests that five genes involved in the transport system of ferric Ab into the cell cytosol form an operon. Construction of disruptants of some selected genes followed by phenotypic analysis supported their predicted biological functions. Interestingly, three additional genes probably involved in the intracellular release of iron from ferric Ab and the secretion of nascent Ab are contained in this cluster. Primer extension and RT-PCR analyses suggested that the Ab cluster, which includes 18 genes, is organized in seven transcriptional units originating from respective Fur-regulated promoter-operator regions.

The work of the ITPA SOL/divertor group is reviewed and implications for ITER discussed. Studies of near SOL gradients have revealed a connection to underlying turbulence models. Analysis of a multi-machine database shows that parallel conduction gradients near the separatrix scale as major radius. New SOL measurements have implicated low-field side transport as driving parallel flows to the inboard side. The high-n nature of ELMs has been elucidated and new measurements have determined that they carry ~10-20% of the ELM energy to the far SOL with implications for ITER limiters and the upper divertor. Analysis of ELM measurements imply that the ELM continuously loses energy as it travels across the SOL-larger gaps should reduce surface loads. The predicted divertor power loads for ITER disruptions has been reduced as a result of finding that the divertor footprint broadens during the thermal quench and that the plasma can lose up to 80% of its thermal energy before the thermal quench (not true for VDEs or ITBs). On the other hand predictions of power loading to surfaces outside the divertor have increased. Disruption mitigation through massive gas puffing has been successful at reducing divertor heat loads but estimates of the effect on the main chamber walls indicate 10s of kG of Be could be melted/mitigation. Estimates of ITER tritium retention have reduced the amount retained/discharge although the uncertainties are large and tritium cleanup may be necessary every few days to weeks. Long-pulse studies have shown that the fraction of injected gas that can be recovered after a discharge decreases with discharge length. The retention rate on the sides of tiles appears to ~ 1-3% of the ion flux to the front surface for C tiles and ~100x less for Mo tiles. T removal techniques are being developed based on surface heating and surface ablation although ITER mixed materials will make T removal more difficult. The use of mixed materials gives rise to a number of potential processes-e.g. reduction of surface melting temperatures (formation of alloys) and reduction of chemical sputtering. Advances in modelling of the ITER divertor and flows have enhanced the capability to match experimental data and predict ITER performance.

Behavior and characteristics of tungsten under impinging high heat-fluxes are investigated in view of the material choices for future devices such as ITER and DEMO. Experiments have been performed in the edge of the TEXTOR tokamak to study melt-layer motion, macroscopic melt layer erosion as well as the changes of the material properties. The parallel heat-flux ranges around q ∼ 45M W/m 2 allowing samples at an impact angle of 35 • to be exposed to 20 − 30M W/m 2 . Melt-layer motion perpendicular to the magnetic field is observed following a Lorentzforce originating from thermoelectric emission of the hot sample. Up to 3 g of tungsten are redistributed forming mountain like structures at the edge of the sample. The typical melt layer thickness is 1 − 1.5mm. Those hills are particularly susceptible to even higher heat-fluxes of up to the full q . Locally the temperature can reach up to 6000K, high levels of evaporation are causing significant erosion in form of continuous fine-spray (∼ 1 · 10 24 atoms m −2 s −1 ). Vaporshielding is occurring and hindering the further heating of the samples. In addition the formation of ligaments and splashes occurs several times during the melt phase ejecting droplets in the order of several 10µm up to 100µm probably caused by a Kelvin-Helmholtz instability evolving in the melt. In terms of material degradation several aspects are considered: formation of leading edges by redistributed melt, bubble formation and re-crystallization. Bubbles are occurring in sizes between µm and 200 µm while recrystallization increases the grain size up to 1.5 mm. The power handling capabilities are thus severely degraded. Melting of Tungsten in future devices is highly unfavorable and needs to be avoided especially in light of uncontrolled transients and possible unshaped PFCs

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A mixed-valence tin oxide, (Sn(2+))2(Sn(4+))O4, was synthesized via a hydrothermal route. The Sn3O4 material consisted of highly crystalline {110} flexes. The Sn3O4 material, when pure platinum (Pt) was used as a co-catalyst, significantly catalyzed water-splitting in aqueous solution under illumination of visible light (λ > 400 nm), whereas neither Sn(2+)O nor Sn(4+)O2 was active toward the reaction. Theoretical calculations have demonstrated that the co-existence of Sn(2+) and Sn(4+) in Sn3O4 leads to a desirable band structure for photocatalytic hydrogen evolution from water solution. Sn3O4 has great potential as an abundant, cheap, and environmentally benign solar-energy conversion catalyst.

The interaction between single-stranded RNAs and liposomes was studied using UV, Fourier Transform Infrared spectroscopy (FTIR) and Circular Dichroism spectroscopy (CD). The effect of the surface characteristics of liposomes, which were composed of 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) and modified with cholesterol (Ch) or 1,2-dioleoyl-3-trimethylammonium propane (DOTAP), on the liposome–RNA interaction was investigated. The fluorescence of 6-(p-toluidino)naphthalene-2-sulfonate (TNS) embedded in the liposome surface (ε = 30–40) was decreased in the presence of tRNA, suggesting that single-stranded tRNA could bind onto the liposome. The dehydration of –PO2− –, guanine (G) and cytosine (C) of tRNA molecules in the presence of liposomes suggested both an electrostatic interaction (phosphate backbone of tRNA and trimethylammonium group of POPC, DOTAP) and a hydrophobic interaction (guanine or cytosine of tRNA and aliphatic tail of lipid). The tRNA conformation on the liposome was determined by CD spectroscopy. POPC/Ch (70/30) maintained tRNA conformation without any denaturation, while POPC/DOTAP(70/30) drastically denatured it. The mRNA translation was evaluated in an Escherichia coli cell-free translation system. POPC/Ch(70/30) enhanced expression of green fluorescent protein (GFP) (116%) while POPC/DOTAP(70/30) inhibited (37%), suggesting that the conformation of RNAs was closely related to the translation efficiency. Therefore, single-stranded RNAs could bind to liposomal membranes through electrostatic and hydrophobic attraction, after which conformational changes were induced depending on the liposome characteristics.

The enhancement of the oxygen reduction reaction (ORR) activity of platinum nanoparticles (Pt NPs) using transition metal oxide (MO x , M = Ti, Nb, Ta, W, Y, and Zr) supports has been examined. To enable the use of transition metal oxides having low electric conductivity as supports, Pt NPs were formed on thin transition metal oxides formed on conducting cup-stacked carbon nanotubes (CSCNTs). Metal oxide composites (M1M2O x ) prepared from two types of transition metal (M1M2: TiNb, NbTa, and TaW) precursors were also used as supports. Pt NPs were photodeposited on MO x /CSCNTs and M1M2O x /CSCNT supports, resulting in MO x /CSCNT- and M1M2O x /CSCNT-supported Pt NP catalysts (abbreviated as Pt/MO x /CSCNTs and Pt/M1M2O x /CSCNTs). Their ORR activities in 0.1 M HClO4 aqueous solution were found to significantly depend on the atomic ratio of M1 and M2 in M1M2O x and the type of metal oxide support. A “volcano-type” dependence of the ORR activity (represented as the current density, mass activity, and specific activity at 0.9 V vs reversible hydrogen electrode (RHE)) on the Pt d-band center, relative to the Fermi level, was obtained in a series of the Pt/MO x /CSCNTs and Pt/M1M2O x /CSCNT catalysts. It was found that the d-band center values (ranging from −3.83 to −3.42 eV) of Pt deposited on MO x /CSCNTs and M1M2O x /CSCNT supports were lower than that (−3.39 eV) of the reference Pt/carbon black (CB) and that the Pt/TiNbO x (Ti/Nb = 1:6.6 in atomic ratio)/CSCNTs with a d-band center of −3.59 eV exhibited the maximum ORR activity, in agreement with the theoretical expectation that an ORR catalyst having a d-band center that is ca. 0.2 eV lower than that of Pt would have maximal ORR activity.

In response to low iron availability, Vibrio parahaemolyticus synthesizes and secretes a polyhydroxycarboxylate-type siderophore vibrioferrin which is composed of 1 mol each of 2-ketoglutaric acid, L-alanine, ethanolamine, and citric acid. We have previously reported the cloning and characterization of the pvuA gene, which encodes the 78-kDa outer membrane receptor protein for ferric vibrioferrin. In this study, nine genes involved in the biosynthesis and transport of vibrioferrin have been identified in the genomic regions surrounding the pvuA gene. The genes were sequenced, and gene disruptants were constructed by insertion mutation for phenotype analysis. Five of the genes, named pvsABCDE, constitute an operon that is expressed under iron-limiting conditions. Homology searches of their predicted protein products suggested that the four genes pvsABDE are implicated in the biosynthesis of the siderophore. Another gene in the same operon, pvsC, encodes a putative exporter that is homologous to members of the major facilitator superfamily of multidrug efflux pumps. The remaining four genes, named pvuBCDE, encode proteins strongly homologous to Escherichia coli FecBCDE, respectively, which are components of the ATP-binding cassette transporter system for ferric dicitrate. Reverse transcriptase PCR analysis revealed that these transport genes are transcribed as a single mRNA with the upstream genes, psuA and pvuA. Phenotypic comparison between the wild-type strain and its targeted gene disruptants supported the biological functions for the respective operons that were expected on the basis of the homology search.