Search results for " Reflection"
showing 10 items of 345 documents
Essential oil counterfeit identification through middle infrared spectroscopy
2018
Abstract Infrared spectroscopy (FTIR) has been employed for a fast quality control of commercial essential oils from different plant species. 47 samples were obtained from Algerian and Spanish market and directly measured, without any previous treatment, by attenuated total reflectance Fourier transform Infrared spectroscopy (ATR-FTIR), in the wavenumber region between 4000 and 550 cm−1. Pure essential oils were obtained by hydro- and steam-distillation extraction methods and their ATR spectra obtained. Results found evidenced the presence of solvents in some commercial formulations and permitted a rapid authentication of pure essential oils correctly extracted from those diluted. The propo…
Origin based classification of crude oils by infrared spectrometry and chemometrics
2019
Abstract Crude oil samples from different Iranian petrol resources in both, raw and mixture forms have been characterized by attenuated total reflectance mid infrared spectroscopy. Obtained spectra were classified by chemometric techniques to propose a method for geological based classification of crude oil samples. Totally 251 samples from 7 petrol fields and 3 mixtures were analyzed. Mean centering and principal component analysis (PCA) supported – leverage value based outlier detection were used as preprocessing approaches. PCA, cluster analysis and soft independent modeling of class analogy (SIMCA) were utilized to classify the spectra. Obtained results confirmed that SIMCA is a robust …
Antennas for the detection of radio emission pulses from cosmic-ray induced air showers at the Pierre Auger Observatory.
2012
The Pierre Auger Observatory is exploring the potential of the radio detection technique to study extensive air showers induced by ultra-high energy cosmic rays. The Auger Engineering Radio Array (AERA) addresses both technological and scientific aspects of the radio technique. A first phase of AERA has been operating since September 2010 with detector stations observing radio signals at frequencies between 30 and 80 MHz. In this paper we present comparative studies to identify and optimize the antenna design for the final configuration of AERA consisting of 160 individual radio detector stations. The transient nature of the air shower signal requires a detailed description of the antenna s…
Detection of local specular gloss and surface roughness from black prints
2007
A combination of optical and tomographic imaging techniques for inspection of local surface roughness and specular gloss of black prints and coated paper are introduced. A diffractive optical-element-based glossmeter (DOG) and a low-coherence interferometer (LCI) were used to obtain local information about the print in terms of topographic and gloss maps. X-ray microcomputed tomography (μCT) was used to obtain 3D local structural information of the coated paper. Gloss and topographic maps were used to determine statistical gloss and roughness parameters. These parameters were useful when analysing the surface condition of prints and coated paper. We found an orientation-dependent gloss slop…
Concept and setup for intraoperative imaging of tumorous tissue via Attenuated Total Reflection spectrosocopy with Quantum Cascade Lasers
2015
A major challenge in tumor surgery is the differentiation between normal and malignant tissue. Since an incompletely resected tumor easily leads to recidivism, the gold standard is to remove malignant tissue with a sufficient safety margin and send it to pathology for examination with patho-histological techniques (rapid section diagnosis). This approach, however, exhibits several disadvantages: The removal of additional tissue (safety margin) means additional stress to the patient; the correct interpretation of proper tumor excision relies on the pathologist’s experience and the waiting time between resection and pathological result can be more than 45 minutes. This last aspect implies unn…
Enhanced perpendicular magnetocrystalline anisotropy energy in an artificial magnetic material with bulk spin-momentum coupling
2019
We systematically investigate the perpendicular magnetocrystalline anisotropy (MCA) in $\mathrm{Co}\ensuremath{-}\mathrm{Pt}/\mathrm{Pd}$-based multilayers. Our magnetic measurement data show that the asymmetric Co/Pd/Pt multilayer has a significantly larger perpendicular magnetic anisotropy (PMA) energy compared to the symmetric Co/Pt and Co/Pd multilayer samples. We further support this experiment by first-principles calculations on ${\mathrm{CoPt}}_{2}, {\mathrm{CoPd}}_{2}$, and CoPtPd, which are composite bulk materials that consist of three atomic layers in a unit cell, Pt/Co/Pt, Pd/Co/Pd, and Pt/Co/Pd, respectively. By estimating the contribution of bulk spin-momentum coupling to the …
Challenging gender relations in PE through cooperative learning and critical reflection
2018
Research continues to highlight how gender is reproduced through pedagogical practice in Physical Education (PE), but there has been much less focus on how it might be challenged. This paper report...
Structural and surface characterization of the polycrystalline system CrxOy · TiO2 employed for photoreduction of dinitrogen and photodegradation of …
1992
The polycrystalline system CrxOy-TiO2, used as a catalyst for photoreactions, was studied by X-ray diffractometric method, visible-ultraviolet diffuse reflectance and infrared spectroscopic methods, surface area determination, and porosimetry to characterize its structural and surface features. Two series of catalysts were prepared by two different methods, namely by coprecipitation and by impregnation. The first series was tested as photocatalysts for the dinitrogen photoreduction in a gas-solid regime and for the phenol photodegradation in a liquid-solid regime. The results indicate that the interaction of chromium ions with OH groups modifies the surface properties of the supports and co…
Granulometric analysis of corneal endothelium specular images by using a germ–grain model
2007
Specular microscopy is widely used to study the human corneal endothelium status in vivo. In this paper, the corneal endothelium is represented as a binary image composed of the cell inscribed circles. The granulometric distribution function of the complement of this image is used as a functional descriptor, which provides information about the shape, size and spatial arrangement of cells. Experimental evaluation using bootstrap techniques shows its ability to discriminate between controls and pathological cases. It represents a reliable and graphical alternative to the classical indices (cell density, hexagonality and coefficient of variation of cell areas), which behave poorly when detect…
All-optical signal processing at ultra-low powers in bottle microresonators using the Kerr effect.
2010
We present experimental results on nonlinear, ultra-low power photonics applications based on a silica whispering-gallery-mode microresonator. Our bottle microresonator combines an ultrahigh quality factor of Q10(8) with a small mode volume V. The resulting Q(2)/V-ratio is among the highest realized for optical microresonators and allows us to observe bistable behavior at very low powers. We report single-wavelength all-optical switching via the Kerr effect at a record-low threshold of 50 microW. Moreover, an advantageous mode geometry enables the coupling of two tapered fiber waveguides to a bottle mode in an add-drop configuration. This allows us to route a CW optical signal between both …