Search results for "aves"
showing 10 items of 2443 documents
Efficient Nucleophilic Degradation of an Organophosphorus Pesticide “Diazinon” Mediated by Green Solvents and Microwave Heating
2019
An efficient strategy for the degradation of organophosphate pesticide Diazinon was investigated. In this work, ionic liquids, bio-based solvents, and two conventional organic solvents were used as reaction media. Kinetics studies by means of half-life (t1/2,h) were followed by 31P NMR and the products analyzed by GC-MS, HPLC-MS and NMR techniques. These results have shown that t1/2 values in ionic liquids were the lowest and also they were able to activate two electrophilic centers in Diazinon, whilst degradation in bio-based solvents occurred slowly by only an aromatic pathway. In addition, a study to estimate the influence of green activation techniques was carried out by using Ultrasoun…
Effect of Supplementation with Wheat Bran Aqueous Extracts Obtained by Ultrasound-Assisted Technologies on the Sensory Properties and the Antioxidant…
2015
Phenolic compounds have antioxidant properties and activate endogenous detoxification defense systems able to scavenge the reactive species of oxygen. The external layers of wheat caryopsis, largely constituting by-products of the milling industry such as bran and various middlings, contain relevant amounts of phenolic compounds. The aim of the research has been to evaluate the effect of supplementation with wheat bran aqueous extracts, obtained by ultrasound-assisted technologies, on the sensory properties and antioxidant activity of dry pasta. The HPLC-DAD characterization of the extract evidenced the presence of ferulic and p-coumaric acids. The supplemented pasta showed significantly h…
On critical behaviour in generalized Kadomtsev-Petviashvili equations
2016
International audience; An asymptotic description of the formation of dispersive shock waves in solutions to the generalized Kadomtsev–Petviashvili (KP) equation is conjectured. The asymptotic description based on a multiscales expansion is given in terms of a special solution to an ordinary differential equation of the Painlevé I hierarchy. Several examples are discussed numerically to provide strong evidence for the validity of the conjecture. The numerical study of the long time behaviour of these examples indicates persistence of dispersive shock waves in solutions to the (subcritical) KP equations, while in the supercritical KP equations a blow-up occurs after the formation of the disp…
1985
Nonlinear optical self diffraction effects for a light beam in a liquid crystalline polymer in its isotropic fluid state was observed. This effect is characterized by the absence of a threshold intensity, a diffraction pattern that does not depend on the polarization of the reading beam relative to that of the writing beam and which cannot be disturbed by transversally applied static electrical fields. This effect is attributed to a thermally induced spatial refractive index modulation. The time constants of the response are of the order of ms.
Third-harmonic light polarization control in magnetically resonant silicon metasurfaces
2021
Nonlinear metasurfaces have become prominent tools for controlling and engineering light at the nanoscale. Usually, the polarization of the total generated third harmonic is studied. However, diffraction orders may present different polarizations. Here, we design an high quality factor silicon metasurface for third harmonic generation and perform back focal plane imaging of the diffraction orders, which present a rich variety of polarization states. Our results demonstrate the possibility of tailoring the polarization of the generated nonlinear diffraction orders paving the way to a higher degree of wavefront control.
Super-resolved Imaging based upon spatial depolarization of light
2010
In this paper we present a new approach allowing the surpassing of the diffraction based limitation for the achievable resolution provided by imaging systems. It is based on an encoding-decoding process of various spatial pixels or regions in the field of view of the imaged object by orthogonal and differently time varying polarization states. The reconstruction of the original spatial information is obtained by applying a decoding process in a way similar to the encoding one. Although all the spatial information is summed and mixed together by the system, the decoding provides super resolved imaging since in every spatial position the undesired spatial information having time varying polar…
Generation of Bessel beam arrays through Dammann gratings.
2012
In this work we apply the Dammann grating concept to generate an equal-intensity square array of Bessel quasi-free diffraction beams that diverge from a common center. We generate a binary phase mask that combines the axicon phase with the phase of a Dammann grating. The procedure can be extended to include vortex spiral phases that generate an array of optical pipes. Experimental results are provided by means of a twisted nematic liquid crystal display operating as a binary π phase spatial light modulator.
Nondiffracting Bessel plasmons.
2011
We report on the existence of nondiffracting Bessel surface plasmon polaritons (SPPs), advancing at either superluminal or subluminal phase velocities. These wave fields feature deep subwavelength FWHM, but are supported by high-order homogeneous SPPs of a metal/dielectric (MD) superlattice. The beam axis can be relocated to any MD interface, by interfering multiple converging SPPs with controlled phase matching. Dissipative effects in metals lead to a diffraction-free regime that is limited by the energy attenuation length. However, the ultra-localization of the diffracted wave field might still be maintained by more than one order of magnitude. This research was funded by the Spanish Mini…
X-Ray diffraction diagram evolution of a BaTiO3ceramic under an electric field
1994
Abstract The X-ray diffraction diagrams of a coarse grained pure BaTiO3 ceramic have been recorded as a function of the applied electric D.C. field. This field was perpendicular to the X-ray incoming surface. The experimental device used allows to record diffraction diagrams while the electric field step by step increases. The intensity ratio of the 002 line over the 200 line increases with the applied electric field. The evolution of the X-ray diffraction line intensities is in correlation with the first polarization curve of the ferroelectric ceramic. These results evidence a contribution of the 90° ferroelectric domains pattern to the X-ray diffraction diagram of BaTiO3.
Soret Effect In Forced Rayleigh-scattering
1987
In forced Rayleigh scattering of mixtures or suspensions the temperature gratings generate, by the Soret effect, concentration gratings that may be very important since they produce both a phase and an amplitude grating superimposed on the principal one. The experimental evidence of their influence was given by Thyagarajan and Lallemand using a mixture of carbondisulfide and ethanol. In this paper we study the temporal behaviour of the concentration grating versus the sample properties and its effect on the detected diffracted beam. Explicit expressions are given for the output intensity taking into account both the generated amplitude and phase gratings.