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11.
C. Devaux J.P. Chapel E. Beyou Ph. Chaumont 《The European physical journal. E, Soft matter》2002,7(4):345-352
Thin layers of polystyrene were grown from surface-grafted nitroxide initiators via controlled “living” free radical polymerization.
The “reactive” Langmuir-Blodgett deposition method allowed an effective control of the initiator layer density leading to
PS brushes with different and high grafting density and stretching. The influence of the grafting density on the layer structure
was studied. Comparison with theoretical predictions for monodispersed brushes in bad solvent was discussed. The thickness
was found to vary linearly with molecular weight and the density dependence was shown using wetting measurements. Special
features of controlled radical nitroxide polymerization from a surface were discussed. A direct comparison of the molecular
weight and polydispersity between surface and bulk polymers was made by de-grafting the brushes into a toluene/HF solution.
Finally, some evidence of a “surface Fischer” effect was shown from re-initiated layers.
Received 20 December 2001 相似文献
12.
Ph. Hägler B. Pire L. Szymanowski O.V. Teryaev 《The European Physical Journal C - Particles and Fields》2002,24(2):261-270
We study Pomeron-Odderon interference effects giving rise to charge and single-spin asymmetries in diffractive electroproduction
of a pair. We calculate these asymmetries, originating from both longitudinal and transverse polarizations of the virtual photon,
in the framework of QCD and in the Born approximation, in a kinematical domain accessible to HERA experiments. We predict
a sizable charge asymmetry with a characteristic dependence on the invariant mass of the pair, which makes this observable very important for establishing the magnitude of the Odderon exchange in hard processes.
The single-spin asymmetry turns out to be rather small. We briefly discuss future improvements of our calculations and their
possible effects on the results.
Received: 18 July 2002 / Published online: 25 October 2002 相似文献
13.
Summary. The reconstruction index of all semiregular permutation groups is determined. We show that this index satisfies 3 £ r(G, W) £ 5 3 \leq \rho(G, \Omega) \leq 5 and we classify the groups in each case. 相似文献
14.
S. A. Klimin M. N. Popova E. P. Chukalina B. Z. Malkin A. R. Zakirov E. Antic-Fidancev Ph. Goldner P. Aschehoug G. Dhalenne 《Physics of the Solid State》2005,47(8):1425-1430
The absorption spectra of Yb2Ti2O7 single crystals and the luminescence and luminescence excitation spectra of Y2Ti2O7: Yb (1%) polycrystals were studied in the temperature range 4.2–300 K. The spectra were analyzed in terms of the crystal-field
theory and the exchange-charge model. Based on the set of crystal-field parameters found for Yb2Ti2O7, analogous sets of parameters were determined for other rare-earth titanates and proved to be in reasonable agreement with
all available experimental data.
__________
Translated from Fizika Tverdogo Tela, Vol. 47, No. 8, 2005, pp. 1376–1380.
Original Russian Text Copyright ? 2005 by Klimin, Popova, Chukalina, Malkin, Zakirov, Antic-Fidancev, Goldner, Aschehoug,
Dhalenne. 相似文献
15.
We classify smooth subvarieties of codimension twoX⊂P
n
, 4≤n≤5, which are arithmetically Cohen-Macaulay and of non general type. By the way we exhibit some classes of non extendable
subvarieties. Then we give new proofs of the classification of scrolls inP
4; finally we consider smooth surfaces of non general type inP
4 arising from rank three vector bundles.
Sunto Classifichiamo le sottovarietà lisce di codimensione dueX⊂P n , 4≤n≤5, aritmeticamente Cohen-Macaulay e non di tipo generale. Nel contempo descriviamo alcune classi di sottovarietà non estendibili. Diamo poi due nuove dimostrazioni della classificazione degli scrolls inP 4; infine consideriamo superfici lisce inP 4, non di tipo generale, associate a fibrati di rango tre.相似文献
16.
Zusammenfassung Mittels des Einsatzes einer Hochdrucksichtzelle wurden Eigenschaften der Kontaktbereiche in Trennverfahren mit unterschiedlichen wäßrigen Lösungen und CO2 unter hohen Drücken untersucht. Die Methode des hängenden Tropfens wurde zur Messung der Grenzflächenspannung bis zu Drücken von 280 bar angewandt. Der mit dem Druck abnehmende Verlauf weist nach der Gibbs'schen Theorie auf die Anreicherung von CO2 in der Phasengrenze. Weiterhin wurde die für Packungskolonnen bedeutsame Feststoffbenetzung in Abhängigkeit von Druck und Oberflächenbeschaffenheit des Feststoffes untersucht. Der die Feststoffbenetzung charakterisierende Kontaktwinkel wurde mittels der Methode der gekippten Platte vermessen und ergab eine schlechtere Benetzung bei höheren Drücken und glatten Stahloberflächen.
相似文献
The effect of interfacial phenomena on mass transport and performance of separations in countercurrent columns with supercritical CO2
Interfacial phenomena affecting countercurrent separation processes have been studied in systems containing aqueous solutions and CO2 at elevated pressures by means of a high pressure optical cell. The pendant drop method was applied in order to measure the interfacial tension up to 280 bar. The decreasing course as a function of the pressure is due to the adsorption of CO2 at the interface according to Gibbs' law. Further, wetting characteristics have been investigated as they are of considerable importance to packed columns. Therefore, the contact angle was determined by the method of the tilting plate and came out to increase with pressure and smoothness of the solid surface, indicating the loss of wettability.
相似文献
17.
Lagrangian relaxation is commonly used in combinatorial optimization to generate lower bounds for a minimization problem.
We study a modified Lagrangian relaxation which generates an optimal integer solution. We call it semi-Lagrangian relaxation
and illustrate its practical value by solving large-scale instances of the p-median problem.
This work was partially supported by the Fonds National Suisse de la Recherche Scientifique, grant 12-57093.99 and the Spanish
government, MCYT subsidy dpi2002-03330. 相似文献
18.
Ph. Choquard B. Piller R. Rentsch P. Vieillefosse 《Journal of statistical physics》1989,55(5-6):1185-1262
We report analytical and numerical studies of surface correlations in finite, homogeneously polarizable, classical Coulomb systems placed in an insulating or conducting environment. Their purpose is to understand the phenomenological, shape-dependent laws of electrostatics, from the point of view of statistical mechanics; we focus on the knowledge of the dielectric susceptibility of the system, a quantity proportional to the equilibrium fluctuation of the system's instantaneous polarization per unit volume. This goal has been achieved for a system in a conducting state. The picture is that the shape-dependent part of the susceptibilities results from the action of unbounded observables (the second moments of the instantaneous polarization of the system) on long-range surface correlations and that the relations of electrostatics are verified by means of shape-dependent thermodynamic limits. This picture is supported (i) by exact solutions and asymptotic analysis of the Debye-Hückel approximation of multicomponent plasmas in disks and spheres with insulating and conducting environment and also in ellipses in a vacuum, and (ii) by computer simulations of a one-component plasma in a disk with different environments, notably a conducting environment with permeable and impermeable wall. These observations have revealed for the first time the reason why the susceptibility of a conducting disk in a conductor with impermeable walls diverges linearly with the radius of the disk: this is due to the occurrence of long-range radial correlations in the conductor. These findings are quantitatively interpreted in terms of a novel canonical Debye-Huckel approximation as contrasted to the ordinary grand canonical version. Lastly a fresh look at the problem of the surface correlations of a conductor in a vacuum, which places the observer close to the surface of the conductor but in the vacuum, is presented and applied to the disk, the ellipse, the cylinder, the sphere, and the wedge. 相似文献
19.
20.
Bréchignac C Cahuzac P Kebaili N Lando A Masson A Schmidt M 《The Journal of chemical physics》2004,121(19):9617-9622
The synthesis of silver rich molybdate clusters is achieved by laser induced chemical reaction of coadsorbed MoO(3) and O(2) molecules on free silver clusters. The reactants MoO(3) and/or O(2) molecules condensed at low temperature (77 K-175 K) on free silver clusters. Then, the silver clusters together with their adsorbed molecules are flashed either ionized with a discharge or ionized and heated by a laser. Then they are cooled down by evaporation. The synthesized chemical compounds are analyzed by a high-resolution time-of-flight mass spectrometer. If only one type of reactant is adsorbed on the cluster, only one oxide molecule is stabilized on the metallic core after the heating and cooling cycle. On the contrary, the coadsorption of the two types of molecules MoO(3) and O(2) on Ag(n) (+), at 77 K, leads to complex aggregates that transform, after laser heating, into a molybdate rich metal clusters. These synthesized species cool down by evaporating silver atoms showing evidence of a binary oxide that is more stable than the metallic core. Moreover we demonstrate that for small size molybdate clusters, a stoichiometric composition may differ from the bulk one. 相似文献