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Diffraction-free and dispersion-free pulsed beam propagation in dispersive media  [PDF]
Miguel A. Porras
Physics , 2001, DOI: 10.1364/OL.26.001364
Abstract: Pulsed Bessel beams of light propagating in free-space experience diffraction effects that resemble those of anomalous dispersion on pulse propagation. It is then shown that a pulsed Bessel beam in a normally dispersive material can remain diffraction- and dispersion-free due to mutual cancellation of diffraction and group velocity dispersion. The size of the Bessel transversal profile for localized transmission is determined by the dispersive properties of the material at the pulse carrier frequency.
Speciation of Fe(II) and Fe(III) by using dispersive liquid-liquid microextraction and flame atomic absorption spectrometry
Bahar, Soleiman;Zakerian, Razieh;
Journal of the Brazilian Chemical Society , 2012, DOI: 10.1590/S0103-50532012000500021
Abstract: an extraction method for fe(iii) from water sample before spectrometric determination was developed. dispersive liquid-liquid microextraction (dllme) technique was successfully used as sample preparation method for flame atomic absorption spectrometry (faas). in the proposed approach, 8-hydroxy quinoline (oxine) was used as chelating agent, chloroform and methanol were selected as extraction and dispersive solvents, respectively. some factors influencing the extraction efficiency of fe(iii) and its subsequent determination were studied and optimized, including: type and volume of extraction and dispersive solvents, ph of sample solution, concentration of the chelating agent and extraction time. under the optimized conditions, the enrichment factor of this method for fe(iii) was 462. the limit of detection for fe(iii) was 4.5 ng ml-1, and the relative standard deviation (rsd) 1.4% (n = 5, c = 400 ng ml-1).
A Hybrid Angular/Energy Dispersive Method to Improve Some Characteristics of Laboratory X-Ray Diffraction  [PDF]
V. Rossi Albertini, D. Bailo, A. Generosi, B. Paci
Modern Instrumentation (MI) , 2012, DOI: 10.4236/mi.2012.11001
Abstract: The Energy Dispersive X-ray Diffraction, generally referred as EDXD, has shown to be a valid alternative to the conventional Angular Dispersive X-ray Diffraction, the ADXD. EDXD exhibits several advantages to its AD counterpart, mainly related to the properties of the polychromatic X-ray beam utilized for diffracting, such as higher signal intensities, a wider accessible region of the reciprocal space, a greater transparency of samples, and a parallel data collection of the q-points in the diffraction pattern acquisition. However, the main drawback of poly-chromaticity lays in the fact that the quantities that modulate the scattered intensity in a diffraction measurement depend on the energy. These quantities are the primary X-ray beam spectrum, polarization, and X-ray absorption, the last producing by far the most critical effect because it rapidly changes as a function of energy. Therefore, a detailed knowledge of the energy dependence of all these quantities is required in EDXD in order to process the data correctly and prevent systematic errors. The difficulty in handling the energy-dependent factors complicates the experimental procedure and may make the measurements unreliable. In the present paper, a hybrid method between the ED and AD X-ray Diffraction is proposed to maintain the advantages of the polychromatic nature of the radiation utilized in EDXD, while preventing the problems produced by the energy-dependent quantities.
Maldi tof mass spectrometry of selected mycotoxins in barley
Shaban Elosta,Dagmar Gajdosova,Blanka Hegrova,Josef Havel
Journal of Applied Biomedicine , 2007,
Abstract: A novel method for the simultaneous determination of the trichothecene mycotoxins deoxynivalenol(DON), nivalenol (NIV), 3-acetyl-deoxynivalenol (3-ADON), and 15-acetyl-deoxynivalenol (15-ADON)in barley and malt extracts has been developed using Matrix Assisted Laser Desorption Ionization Timeof Flight Mass Spectrometry (MALDI TOF MS). This technique enables highly sensitive and fastanalysis and/or detection using very small samples. In this work several matrices were examined and themost suitable ones were identified. Statistical analysis was carried out to verify the ability of the systemto determine the mycotoxins in a real sample. Test for the accuracy of the method, repeatability, limit ofdetection (LOD) and limit of quantification (LOQ) were studied. Moreover, the accuracy of the methodwas confirmed by comparing analytical data to certified values from reference materials for thosemycotoxins. In addition, a comparison of the analytical parameters for the determination of DON, 3-ADON, 15-ADON, and Nivalenol was carried out. This work opens up the possibility of very sensitivedetermination of the selected mycotoxins in barley, malt, cereals and food.
Diffraction grating revisited: a high-resolution plasmonic dispersive element  [PDF]
V. Mikhailov,J. Elliott,G. Wurtz,P. Bayvel,A. V. Zayats
Physics , 2005,
Abstract: The spectral dispersion of light is critical in applications ranging from spectroscopy to sensing and optical communication technologies. We demonstrate that ultra-high spectral dispersion can be achieved with a finite-size surface plasmon polaritonic (SPP) crystal. The 3D to 2D reduction in light diffraction dimensions due to interaction of light with collective electron modes in a metal is shown to increase the dispersion by some two orders of magnitude, due to a two-stage process: (i) conversion of the incident light to SPP Bloch waves on a nanostructured surface and (ii) Bloch waves traversing the SPP crystal boundary. This has potential for high-resolution spectrograph applications in photonics, optical communications and lab-on-a-chip, all within a planar device which is compact and easy to fabricate.
Background corrected dispersive liquid-liquid microextraction of cadmium combined with flame atomic absorption spectrometry
Karim-Nezhad, Ghasem;Ahmadi, Mohammad;Zare-Dizajdizi, Behruz;
Journal of the Brazilian Chemical Society , 2011, DOI: 10.1590/S0103-50532011000900026
Abstract: a new procedure was developed for dispersive liquid-liquid micro extraction of cadmium prior to its determination by flame atomic absorption spectrometry. the major difficulty in combination of dispersive liquid-liquid microextraction with flame atomic absorption spectrometry is high background absorption of the extraction and disperser solvents that covers the absorbance of analyte. the background absorption was removed by changing the solvent of sedimented phase from organic to aqueous. in the proposed approach, tetrachloroethylene (c2cl4) and tetrahydroforan (thf) were used as extraction and dispersive solvents respectively. dithizone was used as complexing agent. several factors that may be affect on the extraction process, such as, extraction solvent, disperser solvent, the volume of extraction and disperser solvent, extraction time, temperature of solution, concentration of chelating agent and ph were optimized. the effects of common coexisting ions on the recovery of cadmium were studied. results showed that cadmium recoveries are almost quantitative in the presence of interfering ions. under the optimal conditions the enrichment and enhancement factors were 34.5 and 26 respectively, the extraction and relative recoveries were 69% and 99% respectively, the calibration graph was linear in the range of 5-150 μg l-1, the detection limit was 1.2 μg l-1 and the relative standard deviation (n = 8) was 2.1%. the proposed method was applied successfully for determination of trace amounts of cadmium in water samples
Determination of pesticide residues in tomato using dispersive solid-phase extraction and gas chromatography/ion trap mass spectrometry
Andrade, Graziela C. R. Moura;Freguglia, Rosana M. O;Furlani, Regina P. Z;Torres, Nádia H;Tornisielo, Valdemar L;
Journal of the Brazilian Chemical Society , 2011, DOI: 10.1590/S0103-50532011000900012
Abstract: tomato crop is frequently damaged by diseases, pests and abiotic stresses, resulting in lower yielding and loss of fruit quality. the intensive use of pesticides in tomatoes without observation of good agriculture practices and regulations has caused great concern with a probable final product contamination. the quechers method of sample preparation was used for the determination of six pesticides (buprofezin, carbofuran, endosulfan-α, endosulfan-β, endosulfan sulfate and monocrotophos) in thirty three tomato samples collected from local market retailers. the method involved extraction with acetonitrile, liquid-liquid partition with addition of mgso4 and nacl followed by dispersive solid phase extraction using primary secondary amine sorbent and the analyses were carried out with a gas chromatography/mass spectrometry equipment by ion trap. recovery studies for different pesticides ranged from 71 to 111% and the relative standard deviation (rsd) was below 15%. no pesticide residue was detected (> lod) among the thirty three tomato samples analysed.
Chemical characterization of groundwater in the area occupied by the cemetery: use of fluorescence spectrometry X-ray energy dispersive (EDXRF)  [cached]
Pedro Daniel da Cunha Kemerich,José Luiz Silvério da Silva,Guilherme Barros,Willian Fernando de Borba
Ambiente e água : An Interdisciplinary Journal of Applied Science , 2012,
Abstract: Generally, the burial of human corpses can contribute to groundwater pollution by the contact of leachate generated from the decomposition of bodies in the unsaturated zone of the subsoil. This process has been investigated in this work that aimed to determine the overall quality of groundwater in the zone occupied by the cemetery. The fluorescence spectrometry X-ray Energy Dispersive (EDXRF) technique was used for groundwater chemical characterization. Five monitoring wells were constructed according to Brazilian norms. The water level fluctuation, the potentiometric surface and the concentrations of the elements calcium, copper, iron, phosphorus and silicon were estimated. The water level appeared quite shallow, ranging between 0.48 to 0.95 m in the dry season. The concentrations range for calcium varied from 4.65 to 17.85 mg L-1, for copper 0.02 ± 0.29 mg L-1, iron 0.57 to 15.96 mg L-1, phosphorus 12.00 to 13.98 mg L-1, and silicon 35.55 to 79.12 mg L-1. It is concluded that the use of EDXRF techniques proved to be rapid and efficient for monitoring the constituents in the groundwater collected in wells under the influence of graveyard in silt-clay soil.
Photometric study of single-shot energy-dispersive X-ray diffraction at a laser plasma facility  [PDF]
O. R. Hoidn,G. T. Seidler
Physics , 2013, DOI: 10.1063/1.4862558
Abstract: The low repetition rates and possible shot-to-shot variations in laser-plasma studies place a high value on single-shot diagnostics. For example, white-beam scattering methods based on broadband backlighter x-ray sources are used to determine changes in the structure of laser-shocked crystalline materials by the evolution of coincidences of reciprocal lattice vectors and kinematically-allowed momentum transfers. Here, we demonstrate that white-beam techniques can be extended to strongly-disordered dense plasma and warm dense matter (WDM) systems where reciprocal space is only weakly structured and spectroscopic detection is consequently needed to determine the static structure factor and thus the ion-ion radial distribution function. Specifically, we report a photometric study of energy-dispersive diffraction (ED-XRD) for structural measurement of high energy density systems at large-scale laser facilities such as OMEGA and the National Ignition Facility. We find that structural information can be obtained in single-shot ED-XRD experiments using established backlighter and spectrometer technologies.
Application of Dispersive Liquid-Liquid Microextraction with Graphite Furnace Atomic Absorption Spectrometry for Determination of Trace Amounts of Zinc in Water Samples  [PDF]
Ali Mazloomifar
International Journal of Analytical Chemistry , 2013, DOI: 10.1155/2013/743792
Abstract: A selective and simple method for separation and preconcentration of zinc ions was developed by using dispersive liquid-liquid microextraction. Parameters that have an effect on the microextraction efficiency such as volume of extraction and disperser solvent, extraction time, and adding salt were investigated. Under optimum conditions, a preconcentration factor of 250 was obtained. The limit of detection (LOD) obtained under the optimal conditions was 0.09?ng?mL?1. The linearity of method was obtained in range of 0.2–50?ng?mL?1 with a correlation coefficient ( ) of 0.9974. The relative standard deviation for 10 replicate determinations at 1.0?ng?mL?1 of zinc was 2.53%. The proposed method was successfully applied to the analysis of zinc in water sample. 1. Introduction Zinc is an essential trace element for humans, animals, plants, and microorganisms. The zinc content in humans is 2–4?g [1]. Zinc plays many fundamental roles in cell replications, gene expression, and in the metabolism of nucleic acid and different proteins [2]. The sensitive, selective, and rapid methods for the determination of zinc are in great demand. Atomic absorption spectrometry (AAS) [3], graphite furnace atomic absorption spectroscopy (GF-AAS) [4], neutron activation analysis (NAA) [5], inductively coupled plasma-atomic emission spectroscopy (ICP-AES) [6], inductively coupled plasma-mass spectrometry (ICP-MS) [7], direct current plasma atomic emission spectrometry (DC-PAES), and X-ray fluorescence are widely applied to the determination of zinc at trace level. Preconcentration technique allows the improvement of detection limit as well as the selectivity of the method. Sample preparation is one of the most important and crucial steps in the whole analytical process. It is often also the bottleneck for rapidly obtaining the desired results, especially for the determination of trace analytes in samples with complex matrix. For the preconcentration and sample preparation several different microextraction methods have been developed, including liquid-liquid extraction [8, 9], solid phase extraction (SPE) [10], sorption and chelating ion exchange [11], solid phase microextraction [12], homogeneous liquid-liquid extraction [13, 14], and dispersive liquid-liquid microextraction (DLLME) [15–17]. In this work, a dispersive liquid-liquid microextraction coupled with graphite furnace atomic absorption spectrometry (GFAAS) has been developed and optimized for the extraction and determination of zinc. The method is based on chemical complexation of zinc(II) by Phenanthraquinone monophenyl
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