Generation of typhoons and hurricanes by a mesoscale turbulence

On the basis of an elaborated theory and numerical computation, it is inferred that typhoons and hurricanes can originate in a region filled by convective turbulent mesovortices.     

On the second-type nonlinear elastic waves in porous media

Nonlinear second-type (matrix) waves are studied with special emphasis on the formation of saw-tooth shock waves. Configurations of the elastic waves in specific cases of porous gas-saturated sedimentary are calculated.     

Linear-dendritic supramolecular complexes as nanoscale reaction vessels for "green" chemistry. Diels-Alder reactions between fullerene C60 and polycyclic aromatic hydrocarbons in aqueous medium

This study describes the first Diels-Alder (DA) reaction performed in aqueous medium with highly hydrophobic compounds-fullerene (C 60) as the dienophile and anthracene (An) or tetracene (Tet) as the dienes, respectively. The reactions are performed in nanocontainers, constructed by self-assembly of linear-dendritic amphiphilic copolymers with poly(ethylene glycol), PEG or poly(ethylene oxide), PEO as the hydrophilic blocks and poly(benzyl ether) monodendrons as the hydrophobic fragments: G3PEO13k, dG3 and dG2. Comparative studies under identical conditions are carried out with an amphiphilic linear-linear copolymer, poly(styrene)1800- block-PEO2100, PSt-PEO, and the nonionic surfactant Igepal CO-720, IP720. The binding affinity of supermolecules built of these amphiphiles toward the DA reagents decreases in the following order: G3PEO13k > dG3 > PSt-PEO > dG2 > IP720. The kinetic constant of binding is evaluated for tetracene and decreases in a similar fashion: 5 x 10 (-7) M/min (G3PEO13k), through 4 x 10 (-7) M/min (PSt-PEO) down to 1.5 x 10 (-7) M/min for IP720. The mobility of substrates encapsulated in the micellar core, estimated by pyrene fluorescence decay, is 95-121 ns for the micelles of the linear-dendritic copolymers and notably higher for PSt-PEO (152 ns), revealing the much denser interior of the linear analogue. The apparent kinetic constant for the DA reaction of C 60 and Tet within the G3PEO13k supermolecule in aqueous medium is markedly higher than in organic solvent (toluene), 208 vs 1.82 M /min. With G3PEO13k the conversions reach 49% for the DA reaction between C 60 and An, and 55% for C 60 and Tet. Besides the monoadduct (26.5% yield) the reaction with An produces exclusively increasing amounts of D 2 h -symmetric antipodal bis-adduct, whose yield reaches up to 22.5% after 48 h. In addition to the environmentally friendly conditions notable advantages of the synthetic strategy described are the extended stability of the linear-dendritic nanovessels, the easy collection of the products formed, and the recovery and reuse of unreacted reagents and linear-dendritic copolymers.     

Two‐level preconditioners for serendipity finite element matrices

In this paper an approach to construct algebraic multilevel preconditioners for serendipity finite element matrices is presented. Two‐level preconditioners constructed in the paper allow to obtain multilevel preconditioners in serendipity case using multilevel preconditioners for linear finite element matrices. Copyright © 2006 John Wiley & Sons, Ltd.     

Functionalization of sterically hindered catechol and <Emphasis Type="Italic">o</Emphasis>-benzoquinone with 2,2,6,6-tetramethylpiperidine 1-oxyl

Sterically hindered 4,6-di-tert-butyl-3-formylcatechol and 3,6-di-tert-butyl-o-benzoquinone react with 4-amino-2,2,6,6-tetramethylpiperidine 1-oxyl to give new chelate ligands of the o-quinone type bearing a 2,2,6,6-tetramethylpiperidine 1-oxyl neutral radical moiety. Structures of the synthesized compounds were established by ESR spectroscopy, IR spectroscopy, mass spectrometry, and X-ray diffraction analysis.     

The Leitmann-Schmitendorf advertising game with n players and time discounting

The extension of the Leitmann-Schmitendorf advertising game to n players and positive time discounting is investigated. We show that the strong time consistency of the open-loop Nash equilibrium is preserved. As to optimal controls, while the boundary solution is unaffected by the number of firms as well as discounting, the inner solution depends on industry structure. The fully symmetric version of the game allows us to identify the parameter regions wherein both solutions are sustainable.     

Temperature controlled Lévy flights of minority carriers in photoexcited bulk n-InP

We study by photoluminescence the spatial distribution of minority carriers (holes) arising from their anomalous photon-assisted diffusion upon photo-excitation at an edge of n-InP slab for temperatures ranging from 300 K to 78 K. Giant enhancement in the spread of holes — over distances exceeding 1 cm from the excitation edge — is seen at lower temperatures. We show that the experiment provides a realization of the “Lévy flight” random walk of holes, in which the Lévy distribution index γ   is controlled by the temperature. The variation γ(T)$\gamma (T)$ is close to that predicted earlier, γ=1−Δ/kT$\gamma =1-\Delta /kT$, where Δ(T)$\Delta (T)$ is the Urbach tailing parameter of the absorption spectra. This theoretical prediction is based on the assumption of a quasi-equilibrium intrinsic emission spectrum in the form due to van Roosbroeck and Shockley.