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81.
Roman Gumeniuk Dr. Miriam Schmitt Walter Schnelle Ulrich Burkhardt Helge Rosner Andreas Leithe‐Jasper 《无机化学与普通化学杂志》2010,636(6):954-961
Two new intermetallic alkaline‐earth palladium borides, SrPd4B and BaPd4B were synthesised and their physical properties were investigated. The crystal structure of SrPd4B was solved from powder X‐ray diffraction data: new structure type, space group Pnma, a = 6.0014(1) Å, b = 5.5041(1) Å, c = 11.8723(2) Å, RI = 0.065, RP = 0.093. BaPd4B is isostructural with a = 6.0883(1) Å, b = 5.6066(1) Å, c = 12.0050(2) Å, RI = 0.062, RP = 0.097. The relationship of this structure type with the series of derivatives of the CaCu5 type is discussed. Calculated electronic band structures for palladium, Pd3B, SrPd5, SrPd4B and SrPd3B are compared. The role of boron and strontium for the electronic properties is discussed in detail. SrPd4B shows metallic behaviour with a DOS(EF) ≈? 1.7 eV–1 · f.u.–1 at the Fermi level. Magnetic properties, electrical resistivity and specific heat capacity measurements reveal that the two compounds are diamagnetic metallic conductors with low electronic density of states, in agreement, with the electronic structure calculations. 相似文献
82.
Arvind Venkataraman Miriam Rosenbaum Jan B.A. Arends Rayko Halitschke Largus T. Angenent 《Electrochemistry communications》2010,12(3):459-462
Here, we show that quorum sensing (QS) modulates the current generation of the anode-respiring bacterium Pseudomonas aeruginosa because it controls the production of phenazines, which mediate the electron transfer to the anode. The current generation by a wildtype (WT) strain P. aeruginosa PA14 and the GacS/GacA protein-regulatory mutant retS was investigated under different environmental conditions. The retS mutant generated significantly higher current (45-fold) than the WT under anaerobic conditions. Anaerobic current generation by the WT was 28-fold higher with extraneously supplied lactones (a QS-signaling molecule). Compared to anaerobic conditions, the WT with some oxygen (microaerobic conditions) exhibited enhanced phenazine production (39-fold) and current levels (48-fold). Iron-rich medium and microaerobic conditions had a negative impact on current generation by retS. All these results were directly linked to QS activity in P. aeruginosa, thus, demonstrating the importance of this bacterial communication system for current generation in BESs. We also show that BESs represent a new tool for real-time investigation of phenazine-related QS activity. 相似文献
83.
Xu-Yuan Peng Xiao-Xia Liu Pei-Jie Hua Dermot Diamond King-Tong Lau 《Journal of Solid State Electrochemistry》2010,14(1):1-7
Nickel oxide (NiOx) and polyaniline (PAni) were electrocodeposited from NiSO4 and aniline through cyclic voltammetric scans to afford PAni–NiOx composite film at controlled pH environment. The electrochemical activities of the film were investigated by cyclic voltammetry
in 0.1 M NaOH and 0.1 M H2SO4, respectively. Typical redox couples of PAni in 0.1 M H2SO4 appeared at approximately 0.2 and 0.4 V vs. saturated calomel electrode (SCE); Ni(II)/Ni(III) redox couple was observed at
approximately 0.4 V vs. SCE in 0.1 M NaOH. The morphologies and elemental components of the films were inspected by scanning
electron microscopy and energy dispersive X-ray diffraction. The stability of nickel oxide in the films was found to be enhanced
against acidic environments. Electrochemical catalytic behavior of NiOx within the composite film was conserved and demonstrated by catalytic oxidation of methanol and ethanol. 相似文献
84.
85.
Emer Lahiff Carol Lynam Niamh Gilmartin Richard O’Kennedy Dermot Diamond 《Analytical and bioanalytical chemistry》2010,398(4):1575-1589
The growing need for analytical devices requiring smaller sample volumes, decreased power consumption and improved performance
have been driving forces behind the rapid growth in nanomaterials research. Due to their dimensions, nanostructured materials
display unique properties not traditionally observed in bulk materials. Characteristics such as increased surface area along
with enhanced electrical/optical properties make them suitable for numerous applications such as nanoelectronics, photovoltaics
and chemical/biological sensing. In this review we examine the potential that exists to use nanostructured materials for biosensor
devices. By incorporating nanomaterials, it is possible to achieve enhanced sensitivity, improved response time and smaller
size. Here we report some of the success that has been achieved in this area. Many nanoparticle and nanofibre geometries are
particularly relevant, but in this paper we specifically focus on organic nanostructures, reviewing conducting polymer nanostructures
and carbon nanotubes. 相似文献
86.
Gabriella Santoni Dr. Miriam Mba Dr. Marcella Bonchio Dr. William A. Nugent Cristiano Zonta Dr. Giulia Licini Prof. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2010,16(2):645-654
The stereoselective oxidation of differently functionalised benzyl phenyl sulfides has been examined by using enantiopure TiIV trialkanolamine complexes. These complexes efficiently catalyse the sulfoxidation with good stereoselectivities. The data highlight the contribution to the stereoselectivity of steric effects and non‐covalent π–π interactions between the aromatic rings of the TiIV complex and those pertaining to the substrates. Enantiomeric excesses have been correlated with the electrostatic potential surfaces (EPS) of the reacting sulfides. The overall study leads to a mechanistic interpretation that explains the stereoselectivity of the system and dissects the role of aromatic and steric interactions in the stereoselective process. 相似文献
87.
Progress from global gyrokinetic simulations in understanding the origin of intrinsic rotation in toroidal plasmas is reported. The turbulence-driven intrinsic torque associated with nonlinear residual stress generation due to zonal flow shear induced asymmetry in the parallel wave number spectrum is shown to scale close to linearly with plasma gradients and the inverse of the plasma current, qualitatively reproducing experimental empirical scalings of intrinsic rotation. The origin of current scaling is found to be enhanced k(∥) symmetry breaking induced by the increased radial variation of the safety factor as the current decreases. The intrinsic torque is proportional to the pressure gradient because both turbulence intensity and zonal flow shear, which are two key ingredients for driving residual stress, increase with turbulence drive, which is R/L(T(e)) and R/L(n(e)) for the trapped electron mode. 相似文献
88.
Rice JE Cziegler I Diamond PH Duval BP Podpaly YA Reinke ML Ennever PC Greenwald MJ Hughes JW Ma Y Marmar ES Porkolab M Tsujii N Wolfe SM 《Physical review letters》2011,107(26):265001
Direction reversals of intrinsic toroidal rotation have been observed in diverted Alcator C-Mod Ohmic L-mode plasmas following electron density ramps. For low density discharges, the core rotation is directed cocurrent, and reverses to countercurrent following an increase in the density above a certain threshold. Such reversals occur together with a decrease in density fluctuations with 2 cm(-1)≤k(θ)≤11 cm(-1) and frequencies above 70 kHz. There is a strong correlation between the reversal density and the density at which the Ohmic L-mode energy confinement changes from the linear to the saturated regime. 相似文献
89.
We study the well-posedness of a linear control system Σ(A,B,C,D) with unbounded control and observation operators. To this end we associate to our system an operator matrix $\mathcal{A}$ on a product space $\mathcal{X}^{p}$ and call it p-well-posed if $\mathcal{A}$ generates a strongly continuous semigroup on $\mathcal{X}^{p}$ . Our approach is based on the Laplace transform and Fourier multipliers. The results generalize and complement those of Curtain and Weiss (Int. Ser. Numer. Math. vol. 91. Birkhäuser, Basel, 1989), Staffans and Weiss (Trans. Am. Math. Soc. 354:3229–3262, 2002) and are illustrated by a heat equation with boundary control and point observation. 相似文献
90.
Miriam Isabel Seifert 《Extremes》2014,17(2):193-219
An effective approach for studying the asymptotics of bivariate random vectors is to search for the limits of conditional probabilities where the conditioning variable becomes large. In this context, elliptical and related distributions have been extensively investigated. A quite general model was presented by Fougères and Soulier (Limit conditional distributions for bivariate vectors with polar representation in Stochastic Models, 2010), who derived a conditional limit theorem for random vectors (X, Y) with a polar representation R · (u(T), v(T)), where R, T are stochastically independent and R is in the Gumbel max-domain of attraction. We reformulate their assumptions, such that they have a simpler structure, display more clearly the geometry of the curves (u(t), v(t)) and allow us to deduce interesting generalizations into two directions: u has several global maxima instead of only one, the curve (u(t), v(t)) is no longer differentiable, but forms a “cusp”. The latter generalization yields results where only random norming leads to a non-degenerate limit statement. Ideas and results are elucidated by several figures. 相似文献