Search results for " Reflection"
showing 10 items of 345 documents
Detecting crop irrigation status in orchard canopies with airborne and ASTER thermal imagery
2007
This work provides a description of the research conducted to assess if ASTER satellite data enable the detection of the water status in orchard tree crops. Summer and winter TERRA-ASTER images were acquired over a study area of Seville in southern Spain over a 6-year period. 1076 olive orchards were monitored in this area, obtaining field location, area, tree density, and irrigation status information. Surface temperature images were obtained using the TES method and 0.5 m resolution panchromatic ortho-rectified imagery collected over the entire area to obtain vegetation cover. A comparison study of the temperature difference between orchards under different irrigation schemes is presented…
2,5-Bis[(E)-2-phenylethenyl]-3,6-bis(pyridin-2-yl)pyrazine
2020
The molecule of the title compound, C30H22N4, exhibits inversion symmetry adopting the shape of a St Andrew's Cross. It shows dihedral angles between adjacent aryl units of around 50° whereas torsion angles of ca 10° are found along the arylene vinylene path.
Determination of quality parameters of beers by the use of attenuated total reflectance-Fourier transform infrared spectroscopy
2005
Abstract The estimation of important quality parameters of beers, such as original and real extracts and alcohol content, has been evaluated by attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR) using a partial least square (PLS) calibration approach. Two sample populations, one consisting of 24 samples and other of 21 samples, obtained from the Spanish market and covering different types of beer were used. The first set was used for building and validating the model, whereas the second, measured 6 months after, was used for evaluating its robustness. The spectral range and the size of the calibration set and its suitability for building the PLS model have been …
Analyzing the anisotropy of thermal infrared emissivity over arid regions using a new MODIS land surface temperature and emissivity product (MOD21)
2015
Abstract The MOD21 Land Surface Temperature and Emissivity (LST&E) product will be included in forthcoming Moderate Resolution Imaging Spectroradiometer (MODIS) Collection 6. Surface temperature and emissivities for thermal bands 29 (8.55 μm), 31 (11 μm) and 32 (12 μm) will be retrieved using the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) Temperature and Emissivity Separation (TES) method adapted to MODIS at-sensor spectral radiances, previously corrected with the Water Vapor Scaling method (MOD21 algorithm). We simulated MOD21 product estimates over two different sandy deserts (i.e. White Sands and Great Sands) using a series of MODIS scenes from 2010 to 2013. T…
Preliminary studies about thermal degradation of edible oils through attenuated total reflectance mid-infrared spectrometry
2009
Abstract Degradation of edible oils during their heating process has been evaluated through the determination of cis -unsaturation and trans -fatty acids together with free fatty acids as a function of time and temperature heating. Two types of cooking oils, sunflower and seed (mixture of different seeds non-detailed), were heated at three different temperatures (147, 171 and 189 °C) during a total time of 1920 min (32 h) shared out in four sessions of 8 h each one, and samples were studied from their spectra obtained by Fourier transform infrared spectrometry using attenuated total reflectance measurements. A critical comparison between different multivariate calibration models built based…
Comparative study of reflectance cells for PLS-FTIR determination of sugars in soft drinks
1998
A comparative study has been carried out between a horizontal Attenuated Total Reflectance (h-ATR) cell and a Cylindrical Internal Reflection (CIR) cell (CIRCLE cell). Both cells were employed for the determination of glucose, fructose, sucrose and total sugar in soft drinks and fruit juices using absorbance measurements at two resolution values (4 and 8 cm–1). Data were processed by Partial Least Squares regression (PLS). Using a resolution of 4 cm–1, mean relative errors of prediction from 0.6% to 1.3% were obtained using the horizontal-ATR and from 0.6% to 2.8% using the CIRCLE cell resulting in a limit of detection from 0.03% in the case of sucrose to 0.21% for total sugar for the h-ATR…
Direct ATR-FTIR determination of sucrose in beet root.
2000
A simple and fast procedure has been developed for the direct determination of sucrose in beet root samples through attenuated total reflectance Fourier transform infrared absorbance measurements (ATR-FTIR) at 1056 cm(-1) with a baseline established between 1187 and 887 cm(-1). The method only requires a previous crushing or liquefaction of samples and it is free from matrix effects and from the interference of minoritary sugars and fermentation molecules. Aqueous solutions of sucrose can be used as standards and recovery values from 101 to 103% were found for spiked concentration levels from 3.5 to 10.5% (w/w). The limit of detection provided by this method corresponds to 0.15% (w/w) of su…
On-line gel permeation chromatography–attenuated total reflectance–Fourier transform infrared determination of lecithin and soybean oil in dietary su…
2007
Gel permeation chromatography (GPC) with attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectrometry detection has been proposed for the simultaneous determination of lecithin and soybean oil in dietary supplements. The method involves the extraction of analytes with dichloromethane in an ultrasound water bath and the injection of 2 ml of centrifuged and filtered extracts into the system integrated by two Envirogel GPC columns (19 mm x150 mm, 19 mm x 300 mm) coupled on-line. Dichloromethane was used as mobile phase. A method has been developed to select the most appropriated wavenumber to be used for the determination of each considered compound from the calculation of a…
Subwavelength Bessel beams in wire media
2013
Recent progress is emerging on nondiffracting subwavelength fields propagating in complex plasmonic nanostructures. In this paper, we present a thorough discussion on diffraction-free localized solutions of Maxwell’s equations in a periodic structure composed of nanowires. This self-focusing mechanism differs from others previously reported, which lie on regimes with ultraflat spatial dispersion. By means of the Maxwell–Garnett model, we provide a general analytical expression of the electromagnetic fields that can propagate along the direction of the cylinder’s axis, keeping its transverse waveform unaltered. Numerical simulations based on the finite element method support our analytical a…
Site-specific atomic order and band structure tailoring in the diluted magnetic semiconductor (In,Ga,Mn)As
2021
Physical review / B 103(7), 075107 (1-13) (2021). doi:10.1103/PhysRevB.103.075107