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81.
The mechanisms of erosion of metal surfaces under the action of submicrosecond (10−9−10−6 s) ion beams in the power density range of P = 106−109 W/cm2 with a particle energy of 1–2000 keV are considered. It is shown that the collective processes associated with the radiation
heating of the surface are of great importance. A model for the erosion is proposed. In accordance with this model, the flow
of atoms of the target leaving the surface being irradiated consists of two independent components caused by collisional sputtering
and evaporation, respectively. The influence of the irradiation parameters on the erosion coefficient and the ratio between
the sputtering and evaporation factors is analyzed. 相似文献
82.
Perzlmaier K Buess M Back CH Demidov VE Hillebrands B Demokritov SO 《Physical review letters》2005,94(5):057202
Quantized spin-wave eigenmodes in single, 16 nm thick and 0.75 to 4 mum wide square permalloy islands with a fourfold closure domain structure have been investigated by microfocus Brillouin light scattering spectroscopy and time resolved scanning magneto-optical Kerr microscopy. Up to six eigenmodes were detected and classified. The main direction of the spin-wave quantization in the domains was found to be perpendicular to the local static magnetization. An additional less pronounced quantization along the direction parallel to the static magnetization was also observed. 相似文献
83.
Using a novel approach to calculate optical properties of strongly correlated systems, we address the old question of the physical origin of the alpha--> gamma transition in Ce. We find that the Kondo collapse model, involving both the f and the spd electrons, describes the optical data better than a Mott transition picture involving the f electrons only. Our results compare well with existing experiments on thin films. We predict the full temperature dependence of the optical spectra and find the development of a hybridization pseudogap in the vicinity of the alpha--> gamma phase transition. 相似文献
84.
85.
Modular Construction of Fluoroarenes from a New Difluorinated Building Block by Cross‐Coupling/Electrocyclisation/Dehydrofluorination Reactions
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Prof. Dr. Jonathan M. Percy Helena Emerson James W. B. Fyfe Dr. Alan R. Kennedy Sergej Maciuk David Orr Lucie Rathouská Dr. Joanna M. Redmond Dr. Peter G. Wilson 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(34):12166-12175
Palladium‐catalysed coupling reactions based on a novel and easy‐to‐synthesise difluorinated organotrifluoroborate were used to assemble precursors to 6π‐electrocyclisations of three different types. Electrocyclisations took place at temperatures between 90 and 240 °C, depending on the central component of the π‐system; nonaromatic trienes were most reactive, but even systems that required the temporary dearomatisation of two arenyl subunits underwent electrocyclisation, albeit at elevated temperatures. Photochemical conditions were effective for these more demanding reactions. The package of methods delivered a structurally diverse set of fluorinated arenes, spanning a 20 kcal mol?1 range of reactivity, by a flexible route. 相似文献
86.
Dr. Marinela M. Dîrtu France Schmit Dr. Anil D. Naik Dr. Ionela Rusu Prof. Dr. Aurelian Rotaru Sergej Rackwitz Dr. Juliusz A. Wolny Prof. Dr. Volker Schünemann Prof. Dr. Leonard Spinu Prof. Dr. Yann Garcia 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(15):5843-5855
A thermochromic 1D spin crossover coordination (SCO) polymer [Fe(βAlatrz)3](BF4)2 ? 2 H2O ( 1? 2 H2O), whose precursor βAlatrz, (1,2,4‐triazol‐4‐yl‐propionate) has been tailored from a β‐amino acid ester is investigated in detail by a set of superconducting quantum interference device (SQUID), 57Fe Mössbauer, differential scanning calorimetry, infrared, and Raman measurements. An hysteretic abrupt two‐step spin crossover (T1/2↓=230 K and T1/2↑=235 K, and T1/2↓=172 K and T1/2↑=188 K, respectively) is registered for the first time for a 1,2,4‐triazole‐based FeII 1D coordination polymer. The two‐step SCO configuration is observed in a 1:2 ratio of low‐spin/high‐spin in the intermediate phase for a 1D chain. The origin of the stepwise transition was attributed to a distribution of chains of different lengths in 1? 2 H2O after First Order Reversal Curves (FORC) analyses. A detailed DFT analysis allowed us to propose the normal mode assignment of the Raman peaks in the low‐spin and high‐spin states of 1? 2 H2O. Vibrational spectra of 1? 2 H2O reveal that the BF4? anions and water molecules play no significant role on the vibrational properties of the [Fe(βAlatrz)3]2+ polymeric chains, although non‐coordinated water molecules have a dramatic influence on the emergence of a step in the spin transition curve. The dehydrated material [Fe(βAlatrz)3](BF4)2 ( 1 ) reveals indeed a significantly different magnetic behavior with a one‐step SCO which was also investigated. 相似文献
87.
Bjoern B. Burckhardt Sergej Ramusovic Jutta Tins Stephanie Laeer 《Biomedical chromatography : BMC》2013,27(4):477-486
The orally active direct renin inhibitor aliskiren is approved for the treatment of essential hypertension in adults. Analytical methods utilized in clinical studies on efficacy and safety have not been fully described in the literature but need a large sample volume ranging from 200 to 700 μL, rendering them unsuitable particularly for pediatric applications. In the assay presented only 100 μL of serum is needed for mixed‐mode solid‐phase extraction. The chromatographic separation was performed on XselectTM C18 CSH columns with mobile phase consisting of methanol–water–formic acid (75:25:0.005, v/v/v) and a flow rate of 0.4 mL/min. Running in positive electrospray ionization and multiple reaction monitoring the mass spectrometer was set to analyze precursor ion 552.2 m/z [M + H]+ to product ion 436.2 m/z during a total run time of 5 min. The method covers a linear calibration range of 0.146–1200 ng/mL. Intra‐run and inter‐run precisions were 0.4–7.2 and 0.6–12.9%. Mean recovery was at least 89%. Selectivity, accuracy and stability results comply with current European Medicines Agency and Food and Drug Administration guidelines. This successfully validated LC‐MS/MS method with a wide linear calibration range requiring small serum amounts is suitable for pharmacokinetic investigations of aliskiren in pediatrics, adults and the elderly. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
88.
Sergej Rackwitz Isabelle Faus Markus Schmitz Harald Kelm Hans-Jörg Krüger K. Kristoffer Andersson Hans-Petter Hersleth Klaus Achterhold Kai Schlage Hans-Christian Wille Volker Schünemann Juliusz A. Wolny 《Hyperfine Interactions》2014,226(1-3):673-678
In order to carry out orientation dependent nuclear resonance scattering (NRS) experiments on small single crystals of e.g. iron proteins and/or chemical complexes but also on surfaces and other micrometer-sized samples a 2-circle goniometer including sample positioning optics has been installed at beamline P01, PETRA III, DESY, Hamburg. This sample environment is now available for all users of this beamline. Sample cooling is performed with a cryogenic gas stream which allows NRS measurements in the temperature range from 80 up to 400 K. In a first test this new sample environment has been used in order to investigate the orientation dependence of the nuclear inelastic scattering (NIS) signature of (i) a dinuclear iron(II) spin crossover (SCO) system and (ii) a hydrogen peroxide treated metmyoglobin single crystal. 相似文献
89.
Transport properties of particles and waves in spatially periodic structures that are driven by external time-dependent forces manifestly depend on the space–time symmetries of the corresponding equations of motion. A systematic analysis of these symmetries uncovers the conditions necessary for obtaining directed transport. In this work we give a unified introduction into the symmetry analysis and demonstrate its action on the motion in one-dimensional periodic, both in time and space, potentials. We further generalize the analysis to quasi-periodic drives, higher space dimensions, and quantum dynamics. Recent experimental results on the transport of cold and ultracold atomic ensembles in ac-driven optical potentials are reviewed as illustrations of theoretical considerations. 相似文献
90.