This work is concerned with two-time-scale jump diffusion models modulated by continuous-time Markov chains. One of our motivations stems from generalization of insurance risk models. The models are hybrid in the sense that they involve both continuous dynamics and discrete events. Two cases are considered. One of them has a fast-varying switching process, and the other contains a rapidly fluctuating diffusion. Two-time scale is used for complexity reduction. Using weak convergence methods, we derive their limit processes. The insight and implication provided by the analysis are: to reduce the complexity, one can ignore the detailed variations and concentrate on the limit or the reduced models. 相似文献
Comprehensive re-investigation of the chemical constituents in the leaves of Vateria indica (Dipterocarpaceae) resulted in the isolation of a novel resveratrol dimeric dimer having a C(2)-symmetric structure, vateriaphenol F (1), and two new O-glucosides of resveratrol oligomers, vateriosides A (2) (resveratrol dimer) and B (4) (resveratrol tetramer), along with a new natural compound (3) and 33 known compounds including 26 resveratrol derivatives. The absolute structures were elucidated by spectroscopic analysis, including two dimensional NMR and circular dichroism (CD) spectra. 相似文献
The solubilities and selectivities for CO2, N2 and CH4 in ionic liquid were predicted using a COSMO based activity coefficient model, COSMO-SAC method. The 1-alkyl-3-methylimidazolium cations were focused in this work. The anion species include tetrafluoroborate [BF4], hexafluorophosphate [PF6], triflate [OTf], dicyanamide [dca] and bis(trifluoromethane)-sulfonimide [Tf2N]. The predicted results of the solubilities of CO2 in the ionic liquids by COSMO-SAC method are in agreement with the experimental data within the averaged deviation of 0.0017 in mole fraction. The predicted results of selectivities for CO2/N2 and CO2/CH4 represent the effects of anion species qualitatively. Permeability through supported liquid membrane can be presented by solubility and diffusion coefficients in the liquid. The permeabilities of CO2 through the ionic liquid membranes were also predicted by a solution-diffusion model with COSMO-SAC method. The predicted results of the CO2 permeabilities through the ionic liquids represent the experimental data within the order of the permeabilities. 相似文献
Thermoelectric NaxCo2O4/Ag composites were synthesized by citric acid complex (CAC) method and Ag precipitation from CH3COOAg aqueous solution on the NaxCo2O4 powders. Effects of the synthesis process on microstructure and thermoelectric performance of NaxCo2O4/Ag composites were investigated. When the NaxCo2O4 CAC powders were dipped in CH3COOAg aqueous solution and dried, fine Ag particles less than around 300 nm in size were precipitated on the surface of NaxCo2O4 powders. After the subsequent sintering process, the flaky Ag phase, the length and thickness of which were up to 5 and 1 μm,
respectively, existed along interfaces between NaxCo2O4 grains. The sizes of Ag particles obtained in this study were found to be smaller than those of the conventionally prepared
NaxCo2O4/Ag composites. The fine dispersion of Ag grains was effective for suppressing the increase in thermal conductivity due to
the addition of metallic phase, Ag, and for improving the thermoelectric performance of NaxCo2O4/Ag composites, suggesting that the synthesis technique composed of the CAC method and Ag precipitation from CH3COOAg aqueous solution is significantly important process for thermoelectric NaxCo2O4/Ag composites. 相似文献
para‐Phenylene‐bridged spirobi(triarylamine) dimer 2 , in which π conjugation through four redox‐active triarylamine subunits is partially segregated by the unique perpendicular conformation, was prepared and characterized by structural, electrochemical, and spectroscopic methods. Quantum chemical calculations (DFT and CASSCF) predicted that the frontier molecular orbitals of 2 are virtually fourfold degenerate, so that the oxidized states of 2 can give intriguing electronic and magnetic properties. In fact, the continuous‐wave ESR spectroscopy of radical cation 2 .+ showed that the unpaired electron was trapped in the inner two redox‐active dianisylamine subunits, and moreover was fully delocalized over them. Magnetic susceptibility measurements and pulsed ESR spectroscopy of the isolated salts of 2 , which can be prepared by treatment with SbCl5, revealed that the generated tetracation 2 4+ decomposed mainly into a mixture of 1) a decomposed tetra(radical cation) consisting of a tri(radical cation) moiety and a trianisylamine radical cation moiety (≈75 %) and 2) a diamagnetic quinoid dication in a tetraanisyl‐p‐phenylendiamine moiety and two trianisylamine radical cation moieties (≈25 %). Furthermore, the spin‐quartet state of the tri(radical cation) moiety in the decomposed tetra(radical cation) was found to be in the ground state lying 30 cal mol?1 below the competing spin‐doublet state. 相似文献
Chiral bis(oxazolinylphenyl)amines proved to be efficient auxiliary ligands for iron and cobalt catalysts with high activity for asymmetric hydrosilylation of ketones and asymmetric conjugate hydrosilylation of enones. 相似文献
Awakening of the Cp one : The bifunctional complex 1 facilitates the interaction with substrates bearing less electrophilic carbon atoms than ketones, epoxides, and imides. The title reaction was applicable to the reduction of Evans' asymmetric alkylation products to the chiral alcohols along with good recovery of the chiral oxazolidinone auxiliary. EWG=electron‐withdrawing group.
Fully interactive : Overlap between extended unoccupied molecular orbitals leads to the high photoconductivity of interactive radical dimers. Sandwich‐type cells (see picture; ITO=indium tin oxide) comprising highly oriented thin films of a disjoint diradical, 4,4′‐bis(1,2,3,5‐dithiadiazolyl) (BDTDA) exhibit a photocurrent with a high on/off ratio at reverse bias voltages and photovoltaic behavior at zero bias voltage.