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81.
Superconducting properties of carbon nanotubes 总被引:1,自引:0,他引:1
Metallic single wall carbon nanotubes have attracted much interest as 1D quantum wires combining a low carrier density and a high mobility. It was believed for a long time that low temperature transport was exclusively dominated by the existence of unscreened Coulomb interactions leading to an insulating behavior at low temperature. However experiments have also shown evidence of superconductivity in carbon nanotubes. We distinguish two fundamentally different physical situations. When carbon nanotubes are connected to superconducting electrodes, they exhibit proximity induced superconductivity with supercurrents which strongly depend on the transmission of the electrodes. On the other hand intrinsic superconductivity was also observed in suspended ropes of carbon nanotubes and recently in doped individual tubes. These experiments indicate the presence of attractive interactions in carbon nanotubes which overcome Coulomb repulsion at low temperature, and enables investigation of superconductivity in a 1D limit never explored before. To cite this article: M. Ferrier et al., C. R. Physique 10 (2009). 相似文献
82.
Christopher Manon 《Journal of Algebraic Combinatorics》2010,31(4):467-489
We study presentations for subalgebras of invariants of the coordinate algebras of binary symmetric models of phylogenetic
trees studied by Buczynska and Wisniewski in (J. Eur. Math. Soc. 9:609–635, 2007). These algebras arise as toric degenerations of projective coordinate rings of the moduli of weighted points on the projective
line, and projective coordinate rings of the moduli of quasiparabolic semisimple rank two bundles on the projective line. 相似文献
83.
84.
Maryline Ferrier Frederic Poineau Gordon D. Jarvinen Kenneth R. Czerwinski 《Journal of Radioanalytical and Nuclear Chemistry》2013,298(3):1809-1817
The chemical and electrochemical properties of technetium metal were studied in 1–6 M HX and in 1 M NaX (pH 1 and 2.5), X = Cl, NO3. The chemical dissolution rates of Tc metal were higher in HNO3 than in HCl (i.e. 8.63 × 10?5 mol cm?2 h?1 in 6 M HNO3 versus 2.05 × 10?9 mol cm?2 h?1 in 6 M HCl). The electrochemical dissolution rates in HNO3 and HCl were similar and mainly depended on the electrochemical potential and the acid concentration. The optimum dissolution of Tc metal was obtained in 1 M HNO3 at 1 V/AgAgCl (1.70 × 10?3 mol cm?2 h?1). The dissolution potentials of Tc metal in nitric acid were in the range of 0.596–0.832 V/AgAgCl. Comparison of Tc behavior with Mo and Ru indicated that in HNO3, the dissolution rate followed the order: Mo > Tc > Ru, and for dissolution potential the order: E diss(Ru) > E diss(Tc) > E diss(Mo). The corrosion products of Tc metal were analyzed in HCl solution by UV–Visible spectroscopy and showed the presence of TcO4 ?. The surface of the electrode was characterized by microscopic techniques; it indicated that Tc metal preferentially corroded at the scratches formed during the polishing and no oxide layer was observed. 相似文献
85.
Cavalier M Walls M Lisiecki I Pileni MP 《Langmuir : the ACS journal of surfaces and colloids》2011,27(8):5014-5020
We report a solution-phase annealing of spherical Co nanocrystals synthesized in reverse micelles and coated with dodecanoic acid. The deposition of a drop of solution on a transmission electron microscope grid shows that a progressive increase in the temperature to 316 °C results in the progressive crystallographic transition from a polycrystalline and probably face-centered cubic Co phase to the single-crystalline hexagonal close-packed (hcp) Co phase. These nanocrystals are highly stable against oxidation and coalescence. We stress that, to our knowledge, this constitutes the first example in the literature of pure hcp-Co spherical single crystals dispersed in solution. These nanocrystals can be freely manipulated and, due to their low size dispersion, can self-organize on various substrates. 相似文献
86.
Coupling amperometry and total internal reflection fluorescence microscopy at ITO surfaces for monitoring exocytosis of single vesicles 总被引:1,自引:0,他引:1
87.
88.
Zhizhuang Xiao Meiqun Wu Stephan Grosse Manon Beauchemin Michelle Lévesque Peter C. K. Lau 《Applied biochemistry and biotechnology》2014,172(1):73-86
Mining fungal genomes for glucoamylase and α-amylase encoding sequences led to the selection of 23 candidates, two of which (designated TSgam-2 and NFamy-2) were advanced to testing for cooked or raw starch hydrolysis. TSgam-2 is a 66-kDa glucoamylase recombinantly produced in Pichia pastoris and originally derived for Talaromyces stipitatus. When harvested in a 20-L bioreactor at high cell density (OD600?>?200), the secreted TSgam-2 enzyme activity from P. pastoris strain GS115 reached 800 U/mL. In a 6-L working volume of a 10-L fermentation, the TSgam-2 protein yield was estimated to be ~8 g with a specific activity of 360 U/mg. In contrast, the highest activity of NFamy-2, a 70-kDa α-amylase originally derived from Neosartorya fischeri, and expressed in P. pastoris KM71 only reached 8 U/mL. Both proteins were purified and characterized in terms of pH and temperature optima, kinetic parameters, and thermostability. TSgam-2 was more thermostable than NFamy-2 with a respective half-life (t1/2) of >300 min at 55 °C and >200 min at 40 °C. The kinetic parameters for raw starch adsorption of TSgam-2 and NFamy-2 were also determined. A combination of NFamy-2 and TSgam-2 hydrolyzed cooked potato and triticale starch into glucose with yields, 71–87 %, that are competitive with commercially available α-amylases. In the hydrolysis of raw starch, the best hydrolysis condition was seen with a sequential addition of 40 U of a thermostable Bacillus globigii amylase (BgAmy)/g starch at 80 °C for 16 h, and 40 U TSgam-2/g starch at 45 °C for 24 h. The glucose released was 8.7 g/10 g of triticale starch and 7.9 g/10 g of potato starch, representing 95 and 86 % of starch degradation rate, respectively. 相似文献
89.
Abderafi Charki C. Ferrier G. Bonnier M. Berrada E. A. Hassani L. Osseni 《Accreditation and quality assurance》2009,14(4):227-230
This article presents the CAFMET (African Committee of Metrology), a non-profit organization that aims to meet the needs of
African countries in the field of metrology. Its objectives are to spread a metrology culture in Africa via various domains
in metrology such as, analysis, tests, and calibration. The difficulties of the development of metrology in Africa and the
different activities, events and projects of the CAFMET are all presented. 相似文献