Skiing manufacturers depend on the development of new skis on trial and error cycles and extensive product testing. Simulation tools, such as the finite element method, might be able to reduce the number of required testing cycles. However, computer programs simulating a ski in the situation of a turn so far lack realistic ski-snow interaction models. The aim of this study was to (a) implement a finite element simulation of a ski in a carved turn with an experimentally validated ski-snow interaction model, and (b) comparison of the simulation results with instantaneous turn radii determined for an actual carved turn. A quasi-static approach was chosen in which the skisnow interaction was implemented as a boundary condition on the running surface of the ski. A stepwise linear function was used to characterise the snow pressure resisting the penetration of the ski. In a carved turn the rear section of the ski interacts with the groove that forms in the snow. Two effects were incorporated in the simulation to model this situation: (a) the plasticity of the snow deformation, (b) the influence of the ski's side-cut on the formation and shape of this groove. The simulation results agreed well with experiments characterising snow penetration. Implementation of the groove in the ski-snow interaction model allowed calculation of the instantaneous turn radii measured in actual turns, but also caused significant numerical instability. The simulation contributes to the understanding of the mechanical aspects of the ski-snow interaction in carved turns and can be used to evaluate new ski designs.
Polymer micelles are an attractive means to solubilize water insoluble compounds such as drugs. Drug loading, formulations stability and control over drug release are crucial factors for drug‐loaded polymer micelles. The interactions between the polymeric host and the guest molecules are considered critical to control these factors but typically barely understood. Here, we compare two isomeric polymer micelles, one of which enables ultra‐high curcumin loading exceeding 50 wt.%, while the other allows a drug loading of only 25 wt.%. In the low capacity micelles, steady‐state fluorescence revealed a very unusual feature of curcumin fluorescence, a high energy emission at 510 nm. Time‐resolved fluorescence upconversion showed that the fluorescence life time of the corresponding species is too short in the high‐capacity micelles, preventing an observable emission in steady‐state. Therefore, contrary to common perception, stronger interactions between host and guest can be detrimental to the drug loading in polymer micelles.
The valence-band electronic structure of a clean Ni(111) surface is investigated by spin-resolved photoemission. At room temperature the orientation of the photoelectron spins on the Bloch sphere and the exchange splitting of surface and bulk states along the surface normal (Γ̅ ) are determined. All investigated states are found to have a sizable exchange splitting >50 meV. Since the splitting is smaller than the intrinsic line width in the spin-integrated spectrum this is only seen with a spin-resolved technique. At room-temperature photoemission reaching above the Fermi level directly shows that the Shockley type surface state S1 has an occupied majority and an unoccupied minority band with a splitting ΔEex=62±15 meV.
AbstractThe valence band electronic structure of a clean Ni(111) surface is investigated by spin-resolved
233Shubnikov-de Haas oscillations including an abrupt phase shift of the extrema position at a critical magnetic field are reproduced by computer simulation allowing a quantitative evaluation of the spin and valley splittings A, and A, with a high accuracy. Varying the gate voltage and tilt angle of a sample in the magnetic field data are obtained over a wide field range. The computer simulation also permits to check the assumptions about the magnetic field dependence of the energy width and the shape of the broadened levels in quantizing magnetic and electric fields. The results obtained for A, and A, both depend on the history of even the same sample.Shubnikov-de Haas-Oszillationen, einschliefllich eines abrupten Phasensprungs fur die Lage der Extrema bei einem kritischen Magnetfeld, werden durch Computer-Simulation reproduziert, wodurch eine quantitative Auswertung der Spin-und Valley-Aufspaltungen 3, und A, mit hoher Genauigkeit moglich wird. Durch Verinderung der Gate-Spannung und des Neigungswinkels der Probe im Magnetfeld werden Daten in einem groflen Feldbereich erhalten. Die numerische Simulation erlaubt ebenso die Prufung der Annahmen fur die Magnetfeldabhangigkeit der Linienbreite und fur die Form der verbreiterten Niveaus in quantisierenden elektrischen und magnetischen Feldern. Die erhaltenen Resultate fur A, und A , hangen beide sogar fur die gleiche Probe von ihrer Vorgeschichte ab.
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