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11.
Nikolaií N. Nekhoroshev Dmitrií A. Sadovskií Boris I. Zhilinskií 《Annales Henri Poincare》2006,7(6):1099-1211
We introduce fractional monodromy in order to characterize certain non-isolated critical values of the energy–momentum map
of integrable Hamiltonian dynamical systems represented by nonlinear resonant two-dimensional oscillators. We give the formal
mathematical definition of fractional monodromy, which is a generalization of the definition of monodromy used by other authors
before. We prove that the 1:( − 2) resonant oscillator system has monodromy matrix with half-integer coefficients and discuss
manifestations of this monodromy in quantum systems.
Communicated by Eduard Zehnder
Submitted: February 25, 2005; Accepted: November 17, 2005 相似文献
12.
Claisen condensation of δ-valerolactone and ethyl trifluoroacetate leads to α-trifluoroacetyl-δ-valerolactone, existing completely in CDCl3 solution as an enol. Upon treatment of this cyclic 1,3-ketoester with aqueous HCl, an acyl-lactone rearrangement takes place. The structure of the resulting pyran was confirmed by an X-ray analysis. The ability of the rearrangement product to lose its carboxylic group under unexpected mild conditions was used for the synthesis of the corresponding 3-unsubstituted cyclic hemi-ketal. 相似文献
13.
Zhi C Bando Y Tang C Xie R Sekiguchi T Golberg D 《Journal of the American Chemical Society》2005,127(46):15996-15997
We report for the first time that boron nitride nanotubes (BNNTs) may be dissolved in organic solvents by wrapping them with a polymer. Transmission electron microscopy and cathodoluminescence studies indicate the strong pi-pi interactions between BNNTs and the polymer. A band gap ranging from 5.2 to 5.5 eV was documented for the BNNTs independent of their geometrical characteristics by using ultraviolet-visible absorption experiments on composite films and thin BNNT films prepared from solutions. 相似文献
14.
Dr. Alexey S. Kiryutin Mikhail S. Panov Dr. Alexandra V. Yurkovskaya Prof. Dr. Konstantin L. Ivanov Prof. Dr. Geoffrey Bodenhausen 《Chemphyschem》2019,20(5):766-772
A study of long-lived spin order in chlorothiophene carboxylates at both high and low magnetic fields is presented. Careful sample preparation (removal of dissolved oxygen in solution, chelating of paramagnetic impurities, reduction of convection) allows one to obtain very long-lived singlet order of the two coupled protons in chlorothiophene derivatives, having lifetimes of about 130 s in D2O and 240 s in deuterated methanol, which are much longer than the T1-relaxation times (18 and 30 s, respectively, at a field =9.4 T). In protonated solvents the relaxation times become shorter, but the lifetime is still substantially longer than . In addition, long-lived coherences are shown to have lifetimes as long as 30 s. Thiophene derivatives can be used as molecular tags to study slow transport, slow dynamics and slow chemical processes, as has been shown in recent years. 相似文献
15.
Yu.N. Panov 《European Polymer Journal》1979,15(4):395-397
It has been established that the Newtonian viscosity of solutions of styrene-acrylic acid (4 mol%) copolymers inionomeric form (0–50 mol%) in DMPh is proportional to exp n (n being the degree of neutralization). The principle of temperature-time-concentration superposition is applicable for the dependence of shear modulus on temperature (20–100°), frequency (10?3–1.5 Hz), decree of neutralization (0–50 mol%) and concentration (15–45 g/dl). These facts can be explained in terms of the rheological similarity of physical networks connected with macromolecular chain entanglements and with salt group interactions. Some details of the model for concentrated polymer solutions are discussed. 相似文献
16.
Talapin DV Shevchenko EV Murray CB Kornowski A Förster S Weller H 《Journal of the American Chemical Society》2004,126(40):12984-12988
We demonstrate the self-organization of CdSe nanorods into nematic, smectic, and crystalline solids. Layered colloidal crystals of CdSe nanorods grow by slow destabilization of a nanocrystal solution upon allowing the diffusion of a nonsolvent into the colloidal solution of nanocrystals. The colloidal crystals of nanorods show characteristic birefringence, which we assign to specific spherulite-like texture of each nanorod assembly. To demonstrate the general character of nanorod self-assembly technique, CdSe/CdS heterostructure nanorods were organized into highly luminescent superlattices. 相似文献
17.
V.G. Kessler A.N. Panov N.Ya. Turova A.Yu. Borissevitch 《Journal of Sol-Gel Science and Technology》1997,8(1-3):1049-1051
The hydrolysis of solutions, containing either LiMo2O4(OPr
i
)5(
i
PrOH) and “La(OPr
i
)3” or LiOPr
i
and La2Mo4O8(OPr
i
)14 in 1∶1 ratio, in toluene or
i
PrOH, by water solutions in isopropanol, leads to formation of monolythic gels. The latter can be converted by drying and
heat treatment at 600°C into a fine powder of pure α-LiLaMo2O8 phase, which is transformed into β-LiLaMo2O8 powder by annealing at 800°C. The sintering of the pellets pressed under 4 bar pressure of α-LiLaMo2O8 powder at 800°C for 2 h converts them into pieces of β-LiLaMo2O8 transparent ceramics, thus providing a route to LiLnMo2O8 laser waveguide materials. 相似文献
18.
E. Kh. Enikeev A. K. Feoktistov M. K. Panov I. M. Krasheninnikova 《Russian Journal of Electrochemistry》2000,36(4):378-386
The composition and structure of layers formed by corrosion products at the open-circuit and passive potentials on the surface
of steel 3 in aqueous media containing sulfate ions, borate ions, or their mixtures are studied by X-ray photoelectron spectroscopy
and secondary ion mass spectrometry. The composition and structure of both the phase surface layers and the adsorption surface
layers are found to depend on the solution nature. The composition and structure of a corrosion product layer; the composition
of the double layer, in particular, the surface charge and potential; and the anion role as a corrosion inhibitor or activator
depend on the way the anion coordinates with the corroding-metal surface. The coordination may be strong, in an inner coordination
sphere (borate ions), or less strong, in an outer coordination sphere (sulfate ions) of a cation on the surface. 相似文献
19.
G. I. Panov G. K. Boreskov A. S. Kharitonov E. M. Moroz 《Reaction Kinetics and Catalysis Letters》1981,16(2-3):247-251
The activity of barium nitride in the isotope exchange of nitrogen is 2–3 orders of magnitude higher than that of Fe and Ru. In the temperature range from 373 to 673 K the activation energy of exchange is 40 kJ/mol.
2–3 Fe Ru. 373–673 40 /.相似文献
20.
Grignard reactions with alkoxysilanes or carbonyl compounds produce alkoxymagnesium halides as by-products. Kinetic measurements for reactions of silanes and of a ketone were performed with Grignard reagents, enriched in alkoxymagnesium halides and taken in a great excess.The alkoxide-type reaction products complex tightly with Grignard reagents and enhance in this way their nucleophilicity, thus accelerating the reaction. However, alkoxides branched at α-C atom exert an unfavorable steric hindrance to reaction resulting in a decrease in the reaction rate. 相似文献