Observation of vector solitons with hidden vorticity

This letter reports the first experimental observation, to our knowledge, of optical vector solitons composed of two incoherently coupled vortex components. We employ nematic liquid crystal to generate stable vector solitons with counterrotating vortices and hidden vorticity. In contrast, the solitons with explicit vorticity and corotating vortex components show azimuthal splitting.     

Preparation of a Hybrid Organic-inorganic Monolith for Extraction and Purification of Quercetin and Myricetin from Chamaecyparis obtusa

A new hybrid organic-inorganic monolithic cartridge was synthesized and used as the selective sorbent for the extraction and purification of quercetin and myricetin from Chamaecyparis obtusa via a solid-phase extraction method.The morphology of the monolithic material was examined by field emission-scanning electron microscopy and a Brunauer-Emmett-Teller（BET） test.The adsorption capacity of the obtained material for quercetin and myricetin was investigated by fitting the adsorption data to four different adsorption equations,of which the LangmuirFreundlich isotherm was selected as the most suitable model.Under optimized conditions,good calibration curves were observed at nine concentrations ranged from 0.5 μg/mL to 100.0 μg/mL of quercetin and myricetin.The extraction recovery ranged from 74.5％ to 84.6％ and the inter-and intra-day relative standard deviations were ＜6％.This type of hybrid monolith has potential for the separation and purification of bioactive compounds from natural plant extracts.     

Parallel Algorithm and Software for Image Inpainting via Sub-Riemannian Minimizers on the Group of Rototranslations

The paper is devoted to an approach for image inpainting developed on the basis of neurogeometry of vision and sub-Riemannian geometry. Inpainting is realized by completing damaged isophotes (level lines of brightness) by optimal curves for the left-invariant sub-Riemannian problem on the group of rototranslations (motions) of a plane SE(2). The approach is considered as anthropomorphic inpainting since these curves satisfy the variational principle discovered by neurogeometry of vision. A parallel algorithm and software to restore monochrome binary or halftone images represented as series of isophotes were developed. The approach and the algorithm for computation of completing arcs are presented in detail.     

Intensity correlations in a coherently prepared Rb vapor in a magnetic field

We have studied the intensity correlations between two orthogonally linearly polarized components of a laser field propagating through a resonant atomic medium. These experiments have been performed in a rubidium atomic vapor. We observe that the correlations between the orthogonally polarized components of the laser beam are maximal in the absence of a magnetic field. The magnitude of the correlations depends on the applied magnetic field, and the magnitude first decreases and then increases with increasing magnetic field. Minimal correlations and maximal rotation angles are observed at the same magnetic fields. The width of the correlation function is directly proportional to the excited state lifetime and inversely proportional to the Rabi frequency of laser field.     

Observation of high-energy electrons from a metal target irradiated by protons with a mean energy of 25 keV

Electrons with abnormally high energies of up to 16 keV are detected from an iron target irradiated by ions (H⁺, Fe⁺, Fe²⁺, Fe³⁺) with energies ranging from 20 to 100 keV from the plasma of a high-power femtosecond laser pulse with an intensity of 10¹⁶ J/(s cm²). These electrons indicate that the energy of an incident ion is almost completely transferred to an electron knocked out of the target. In a range of 6–16 keV, the spectrum of electrons knocked out of the K shell of iron atoms by protons with an energy of 22 ± 2 keV is quasi-exponential with an exponent of 4 keV. For 8-keV electrons, the double differential cross section for ionization by such protons is estimated as 10^?7 b/(eV sr).     

Spectral scattering properties of a nanohole in a noble-metal film in the evanescent waves area

The effect of enhanced optical transmission through subwavelength holes and their arrays is used for multiple practical applications especially in optical antennas and local biosensors design. This effect is usually considered under excitation of plane wave propagating at the normal direction to the screen surface. In this work the effect of extreme transmission through the hole in the evanescent wave's area is in focus. The discrete sources method has been applied to analyse the spectral characteristics of light scattered by a cylindrical nanohole in a noble-metal film on a prism surface. The influence of the wavelength, incident angle, film materials and hole's filling on the scattering characteristics has been investigated. A close correlation between the effect of extreme transmission and the surface plasmon resonances has been detected.     

Surface morphology of GaN nanorods grown by catalyst-free hydride vapor phase epitaxy

GaN nanorods were grown on c-plane sapphire substrates by using catalyst-free hydride vapor phase epitaxy (HVPE). The effects of substrate temperature, Ga boat temperature, and Ga pretreatment on the surface morphology of GaN nanorods were investigated. From the dependence of a radial and axial growth rate on the substrate temperature, the kinetically limited process was found to be a rate determining step in the growth of GaN nanorods in HVPE. In addition, the activation energy of the growth along the both axial and radial directions were estimated. The dependence of a Ga boat temperature and the Ga pretreatment effect revealed that the density of nanorods were dependent on the flux of Ga species on the substrate.     

Preparation of peri-annulated indoles from polynitro compounds

A novel peri-annulated heterocyclic system of 1,2-dihydrobenz[6,7]oxepino[4,3,2-cd]indole was prepared starting from TNT via 4,6-dinitro-1-tosylindoline as a key intermediate. Base-induced CC bond shift in 1,2-dihydrobenz[6,7]oxepino[4,3,2-cd]indoles affords isomeric 2,11-dihydrobenz[6,7]oxepino[4,3,2-cd]indoles.     

Transformations of allylamine and N-allylacetamide on triosmium cluster complexes with hemilabile ligands

The cluster complexes (μ-H)Os₃(μ-OCR)(СО)₁₀ (R = Me (1); R = Ph (2)) catalyze the allylic rearrangement of N-allylacetamide at room temperature. Microwave irradiation greatly (by more than several thousand-fold) accelerates the reaction between the solution of 2 and allylacetamide. The interaction of cluster 2 with allylamine both at room and elevated temperatures results in cleavage of the C–N bond and coordination of the allylic fragment to one of the osmium atoms with the formation of Os₃(CO)₉(μ,η²-OC-Ph)(η³-C₃H₅) (4) cluster.     

Yan’s oscillation theorem revisited

Yan’s contribution [J. Yan, Oscillation theorems for second order linear differential equations with damping, Proc. Amer. Math. Soc. 98 (1986) 276–282] was an important breakthrough in the development of the Theory of Oscillation. This frequently cited paper has stimulated extensive investigations in the field. During the last decade, an integral oscillation technique has been developed to such an extent as to allow us to revisit Yan’s fundamental oscillation theorem and remove one of the conditions, leaving the other assumptions and the conclusion intact, thus enhancing this keystone result.