Search results for " Optics"
showing 10 items of 5880 documents
Effect of operation conditions of the drop-on-demand aerosol generator on aerosol characteristics: Pseudo-cinematographic and plasma mass spectrometr…
2014
Abstract The recently presented drop-on-demand (DOD) aerosol generator overcomes some of the drawbacks of pneumatic nebulization, as its aerosol is no longer generated by gas–liquid interaction. In the current study, an advanced imaging technique is presented, based on a CCD camera equipped with magnifying telecentric optics to allow for fast, automated and precise aerosol characterization as well as fundamental studies on the droplet generation processes by means of pseudo-cinematography. The DOD aerosol generator is thoroughly characterized regarding its droplet size distribution, which shows few distinct populations rather than a continuous distribution. Other important figures, such as …
An Overview of Green Analytical Techniques in the Spectrometric Analysis of Environmental and Biological Samples
2009
ABSTRACT This literature survey presents in a nutshell different parameters for the effectiveness of the green spectrometric procedures, which have been applied to the determination of organics, inorganics, and metal ions in different matrices. The following issues were considered: the main aspects of miniaturization, reagent replacement, reduction of wastes, and on-line recovery and detoxification, which made the analytical procedures sustainable. Also, a discussion of analytical characteristics along with spectrometric methodologies and applications is included.
Application of infrared spectroscopy as Process Analytics Technology (PAT) approach in biodiesel production process utilizing Multivariate Curve Reso…
2019
Abstract Process Analytical Technology means at-line collection of analytical information from the process when the reaction is in progress. Obtained information enables process engineers to better control the Critical Process Parameters and direct the reaction to desirable routs. Near-infrared spectroscopy due to its analytical features, as well as the high capability of automation, versatile sampling and spectral acquisition methods is a useful tool in process monitoring when coupled to chemometrics. The Multiple Scatter Correction preprocessing technique and Alternative Least Square method can extract spectral and concentration information of a reaction mixture simultaneously, were emplo…
FluorMODleaf: A new leaf fluorescence emission model based on the PROSPECT model
2010
International audience; A new model of chlorophyll a fluorescence emission by plant leaves, FluorMODleaf, is presented. It is an extension of PROSPECT, a widely used leaf optical properties model that regards the leaf as a pile of N absorbing and diffusing elementary plates. In FluorMODleaf, fluorescence emission of an infinitesimal layer of thickness dx is integrated over the entire elementary plate. The fluorescence source function is based on the excitation spectrum of diluted isolated thylakoids and on the emission spectra of isolated photosystems, PSI and PSII, which are the main pigment–protein complexes involved in the initial stages of photosynthesis. Scattering within the leaf is p…
Evaluation of Sentinel-2 Red-Edge Bands for Empirical Estimation of Green LAI and Chlorophyll Content
2011
ESA’s upcoming satellite Sentinel-2 will provide Earth images of high spatial, spectral and temporal resolution and aims to ensure continuity for Landsat and SPOT observations. In comparison to the latter sensors, Sentinel-2 incorporates three new spectral bands in the red-edge region, which are centered at 705, 740 and 783 nm. This study addresses the importance of these new bands for the retrieval and monitoring of two important biophysical parameters: green leaf area index (LAI) and chlorophyll content (Ch). With data from several ESA field campaigns over agricultural sites (SPARC, AgriSAR, CEFLES2) we have evaluated the efficacy of two empirical methods that specifically make use of the…
Towards a revisitation of vesuvianite-group nomenclature: the crystal structure of Ti-rich vesuvianite from Alchuri, Shigar Valley
2016
Vesuvianite containing 5.85 wt% TiO2from an Alpine-cleft-type assemblage outcropped near Alchuri, Shigar Valley, Northern Areas, has been investigated by means of electron microprobe analyses, gas-chromatographic analysis of H2O, X-ray powder diffraction, single-crystal X-ray structure refinement,27Al NMR,57Fe Mössbauer spectroscopy, IR spectroscopy and optical measurements. Tetragonal unit-cell parameters are:a= 15.5326 (2),c= 11.8040 (2) Å, space groupP4/nnc. The structure was refined to finalR1= 0.031,wR2= 0.057 for 11247I> 2σ(I). A general crystal-chemical formula of studied sample can be written as follows (Z= 2):[8–9](Ca17.1Na0.9)[8]Ca1.0[5](Fe2+0.44Fe3+0.34Mg0.22)[6](Al3.59Mg0.41)…
Study of liquid–liquid extraction of ethanol + water azeotropic mixtures using two imidazolium-based ionic liquids
2018
Abstract The present work was focused on the study of two imidazolium-based ionic liquids (ILs) as solvents in liquid–liquid extraction of ethanol from aqueous mixtures. With this aim, the experimental liquid–liquid equilibria (LLE) data of water (1) + ethanol (2) + 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([emim][Tf2N]) (3) and water (1) + ethanol (2) + 1-hexyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([hmim][Tf2N]) (4) systems were obtained at different temperatures: 283.2, 303.2, and 323.2 K, in order to check the influence of temperature. The results were correlated by non-random two-liquid (NRTL) and universal quasichemical (UNIQUAC) models with good c…
Rayleigh and Brillouin scattering in a lysozyme–water mixture: An unusual behavior around 343K
2011
Abstract This article describes Rayleigh and Brillouin light scattering studies on a lysozyme–water mixture from 293 K to 355 K. The scattering intensities from this system are compared with those from a sodium acetate buffer used to dissolve the lysozyme. It is found that in the vicinity of 343 K the lysozyme–water mixture becomes opalescent, and the intensity of the Brillouin peaks decreases and almost vanishes, to be restored at temperatures above 343 K. Around the same temperature the intensity of the central, unshifted Rayleigh peak, however, increases strongly. No such behavior was observed for the sodium acetate buffer. The analysis of the experimental data indicates an irreversible …
Accurate determination of element species by on-line coupling of chromatographic systems with ICP-MS using isotope dilution technique
1998
Abstract The instrumental design for coupling different liquid chromatographic systems such as ion, reversed phase, and size exclusion chromatography as well as capillary gas chromatography, with ICP-MS for the determination of element species is described. For accurate analyses obtaining ‘real time’ concentrations of chromatographic peaks, the isotope dilution mass spectrometric (IDMS) technique is applied. Two different spiking modes are possible, one using species-specific and another one using species-unspecific spike solutions of isotope-enriched labelled compounds. The species-specific mode is only possible for element species well defined in their structure and composition, for examp…
Method development for the determination of 1,1-dimethylhydrazine by the high-performance liquid chromatography-mass spectrometry technique.
2018
Unsymmetrical dimethyl hydrazine is highly toxic, carcinogenic compound, widely used for organic synthesis and drug development. Therefore, due to its high reactivity, direct analysis is problematic. Current study proposes to use derivatization reaction to increase selectivity and sensitivity of high-performance liquid chromatography–mass spectrometry method. Different derivatization agents were tested and optimal reaction media was found. Derivatization was performed by using small amounts of reagents to lower the cost of analysis. The full validation of the method was performed and it can be used in a routine control in pharmaceutical analysis. Method sensitivity is 0.15 ppm, and lineari…