Search results for "Magnetism"
showing 10 items of 1934 documents
Enhancing effect of alpha-hydroxyacids on "in vitro" permeation across the human skin of compounds with different lipophilicity.
2005
The percutaneous penetration-enhancing effects of glycolic acid, lactic acid and sodium lauryl sulphate through the human epidermis was investigated using 5-fluorouracil as a hydrophilic model permeant and three compounds belonging to the phenylalcohols: 2-phenyl-ethanol, 4-phenyl-butanol and 5-phenyl-pentanol. The lipophilicity values of the compounds ranged from log Poct -0.95 to 2.89. The effect of the enhancer concentration was also studied. Skin pretreatment with aqueous solutions of the three enhancers did not increase the permeability coefficient of the most lipophilic compound (log Poct = 2.89). For the other compounds assayed, the increase in the permeability coefficients depended …
A rigidity theorem for Lagrangian deformations
2005
We consider deformations of singular Lagrangian varieties in symplectic manifolds. We prove that a Lagrangian deformation of a Lagrangian complete intersection is analytically rigid provided that this is the case infinitesimally. This result is given as a consequence of the coherence of the direct image sheaves of relative infinitesimal Lagrangian deformations.
Optical gain, spontaneous and stimulated emission of surface plasmon polaritons in confined plasmonic waveguide
2010
International audience; We develop a theoretical model to compute the local density of states in a confined plasmonic waveguide. Based on this model, we derive a simple formula with a clear physical interpretation for the lifetime modification of emitters embedded in the waveguide. The gain distribution within the active medium is then computed following the formalism developed in a recent work [Phys. Rev. B 78, 161401 (2008)], by taking rigorously into account the pump irradiance and emitters lifetime modifications in the system. We finally apply this formalism to describe gain–assisted propagation in a dielectric–loaded surface plasmon polariton waveguide.
Selection and characterization of adsorbents for the analysis of an explosive-related molecule traces in the air
2013
International audience; This study is focused on the development of a 3D micro-preconcentrator for a sensitive analysis of an explosive-related compound: orthonitrotoluene (ONT). A set of potentially efficient adsorbents for the pre-concentration of ONT was investigated here. An in-depth characterization of their textural properties was carried out in order to better understand their adsorption behavior toward the target analyte. More particularly, this study allowed highlighting the interesting adsorption features of a hydrophobic zeolite and a porous activated carbon in relation to their preconcentration performances toward ONT at the ppb level. Moreover, we found a difference in the adso…
Pressure-induced magnetic switching and linkage isomerism in K0.4Fe4[Cr(CN)6]2.8 x 16 H2O: X-ray absorption and magnetic circular dichroism studies.
2008
The effect of applied pressure on the magnetic properties of the Prussian blue analogue K0.4Fe4[Cr(CN)6]2.8 x 16 H2O (1) has been analyzed by dc and ac magnetic susceptibility measurements. Under ambient conditions, 1 orders ferromagnetically at a critical temperature (T(C)) of 18.5 K. Under application of pressure in the 0-1200 MPa range, the magnetization of the material decreases and its critical temperature shifts to lower temperatures, reaching T(C) = 7.5 K at 1200 MPa. Pressure-dependent Raman and Mossbauer spectroscopy measurements show that this striking behavior is due to the isomerization of some Cr(III)-C[triple bond]N-Fe(II) linkages to the Cr(III)-N[triple bond]C-Fe(II) form. A…
Investigation into the reaction of (t-BuC5H4)2Nb(η2-Te2)H with CH3Li: Hydride abstraction versus telluride methylation
2007
Abstract The reaction of [ Cp 2 ′ Nb ( Te 2 ) H ] ( 1 ) (Cp′ = t -BuC 5 H 4 ) with CH 3 Li in THF was examined by variable temperature 1 H NMR, ESR and mass spectroscopic means. From these methods it is evident that the diamagnetic compounds [ Cp 2 ′ NbH 2 ( TeCH 3 ) ] ( 2 ) and [ Cp 2 ′ Nb ( Te ) CH 3 ] ( 3 ) as well as the paramagnetic compound [ Cp 2 ′ Nb ( TeCH 3 ) 2 ] ( 4 ) form simultaneously. In the subsequent reaction of the intermediate solution with [Co 2 (CO) 8 ] compound 4 was consumed and the compound [ Cp 2 ′ Nb ( μ - TeCH 3 ) 2 Co(CO) 2 ] ( 5 ) formed in good yield. Complex 5 was characterized by IR and variable temperature 1 H NMR spectroscopies. Electrochemical two-electro…
Temperature dependence of the non-local spin Seebeck effect in YIG/Pt nanostructures
2017
We study the transport of thermally excited non-equilibrium magnons through the ferrimagnetic insulator YIG using two electrically isolated Pt strips as injector and detector. The diffusing magnons induce a non-local inverse spin Hall voltage in the detector corresponding to the so-called non-local spin Seebeck effect (SSE). We measure the non-local SSE as a function of temperature and strip separation. In experiments at room temperature we observe a sign change of the non-local SSE voltage at a characteristic strip separation d0, in agreement with previous investigations. At lower temperatures however, we find a strong temperature dependence of d0. This suggests that both the angular momen…
Ferromagnetic gyroscopes for tests of fundamental physics
2020
A ferromagnetic gyroscope (FG) is a ferromagnet whose angular momentum is dominated by electron spin polarization and that will precess under the action of an external torque, such as that due to a magnetic field. Here we model and analyze FG dynamics and sensitivity, focusing on practical schemes for experimental realization. In the case of a freely floating FG, we model the transition from dynamics dominated by libration in relatively high externally applied magnetic fields, to those dominated by precession at relatively low applied fields. Measurement of the libration frequency enables in situ measurement of the magnetic field and a technique to reduce the field below the threshold for w…
Influence of Proton Conducting Cations on the Structure and Properties of 2D Anilate-Based Magnets
2017
The syntheses, structures, magnetic, and proton conductivity properties of a family of bimetallic anilate-based compounds with inserted alkylammonium cations are presented. The structures of (Me2NH2)[MnIICrIII(Br2An)3]·2H2O (1), (Et2NH2)[MnIICrIII(Br2An)3] (2), (Et3NH)[MnIICrIII(Cl2An)3] (3), and [(Et)(i-Pr)2NH]-[MnIICrIII(Br2An)3]·(CHCl3)0.5·(H2O) (4) contain a 2D anionic network formed by Mn(II) and Cr(III) ions linked through anilate ligands. In 1, 2, and 3, the hexagonal holes of this network are occupied by Me2NH2+, Et2NH2+, or Et3NH+ cations. Interestingly, the small increase of size of the templating cation in 4 ([(Et)(i-Pr)2NH]+ in the place of Me2NH2+, Et2NH2+ or Et3NH+), gives ris…
Micro magnetofluidics: droplet manipulation of double emulsions based on paramagnetic ionic liquids
2013
The ability to control and manipulate discrete fluid droplets by magnetic fields offers new opportunities in microfluidics. A surfactant-free and easy to realize technique for the continuous generation of double emulsion droplets, composed of an organic solvent and a paramagnetic ionic liquid, is applied. The inner phase of the emulsion droplet consists of imidazolium-based ionic liquids with either iron, manganese, nickel or dysprosium containing anions which provide paramagnetic behaviour. The double emulsion droplets are dispersed in a continuous phase of FC-40. All substances - the organic phase, the paramagnetic ionic liquid and the continuous phase -are immiscible. The magnetic proper…