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Emission Measurements (emission + measurement)
Selected AbstractsCharacterization of flow regime transition and particle motion using acoustic emission measurement in a gas-solid fluidized bedAICHE JOURNAL, Issue 5 2010Wang Jingdai Abstract Particle motion is a major determinant of the dynamical performance of a fluidized bed. It plays an important role in determining and optimizing the complex correlation of fluidization condition between particle-particle and particle-environment in a system. A passive acoustic emission (AE) technique is applied to monitor, characterize, and control the fluidization condition of polyethylene particles in a gas-solid fluidized bed. Experimental results show that AE signals are very sensitive to the particle movements by analyzing energy distribution, which can help to understand the status of the system. The AE energy temporal analysis is further used to identify the transition of flow regimes. Moreover, the activity of particle motion can be quantitatively determined by using a combination of granular temperature and AE spatial energy analysis. This work provides valuable insights into the dynamic behavior of particles in a gas-solid fluidized bed based on AE technique. © 2009 American Institute of Chemical Engineers AIChE J, 2010 [source] Comparison of the spectral emission of lux recombinant and bioluminescent marine bacteria,LUMINESCENCE: THE JOURNAL OF BIOLOGICAL AND CHEMICAL LUMINESCENCE, Issue 3 2003Gérald Thouand Abstract The purpose of the present paper was to study the influence of bacteria harbouring the luciferase-encoding Vibrio harveyi luxAB genes upon the spectral emission during growth in batch-culture conditions. In vivo bioluminescence spectra were compared from several bioluminescent strains, either naturally luminescent (Vibrio fischeri and Vibrio harveyi) or in recombinant strains (two Gram-negative Escherichia coli::luxAB strains and a Gram-positive Bacillus subtilis::luxAB strain). Spectral emission was recorded from 400,nm to 750,nm using a highly sensitive spectrometer initially devoted to Raman scattering. Two peaks were clearly identified, one at 491,500,nm (± 5,nm) and a second peak at 585,595 (± 5,nm) with the Raman CCD. The former peak was the only one detected with traditional spectrometers with a photomultiplier detector commonly used for spectral emission measurement, due to their lack of sensitivity and low resolution in the 550,650,nm window. When spectra were compared between all the studied bacteria, no difference was observed between natural or recombinant cells, between Gram-positive and Gram-negative strains, and growth conditions and growth medium were not found to modify the spectrum of light emission. Copyright © 2003 John Wiley & Sons, Ltd. [source] Profile: air quality regulation policy in PortugalENVIRONMENTAL POLICY AND GOVERNANCE, Issue 1 2004Joăo F. P. Gomes Ten years after the publication of the first air quality laws in Portugal, and seven years after the publication of the respective emission limits, it seems appropriate to analyse the degree of law enforcement by the Portuguese manufacturing industry. Therefore, based on the emission measurements made regularly by ISQ as the only officially accredited laboratory, a set of about 400 sources is analysed in terms of the compliance with the emission limits regarding total suspended particulate, sulphur dioxide, nitrogen oxides and VOCs. The compliance is evaluated through a non-dimensional parameter and plotted versus the emission flow rate to derive conclusions: it was noticed that emission limits are generally respected regarding sulphur dioxide and nitrogen oxides, which does not happen for the other pollutants considered in this study. However, the non-compliance occurs mainly for very low emission flow rates, which suggests some alterations in the emission limits' applicability, which is being revised at the moment. Copyright © 2004 John Wiley & Sons, Ltd and ERP Environment. [source] The Effect of Grain Size on the Deformation Behaviour of Magnesium Alloys Investigated by the Acoustic Emission Technique,ADVANCED ENGINEERING MATERIALS, Issue 5 2006J. Bohlen Extruded round bars from magnesium alloys ZM21, ZK30, ZE10 and ZEK100 with various grain sizes were tested in tension and compression. The effect of grain size on the deformation behaviour of the alloys was investigated through the Hall-Petch relation. In-situ acoustic emission measurements were conducted during testing to evaluate the mechanisms of plastic deformation. The results are discussed with respect to twinning as one important deformation mechanism in magnesium alloys. [source] An optimized kinetics model for OH chemiluminescence at high temperatures and atmospheric pressuresINTERNATIONAL JOURNAL OF CHEMICAL KINETICS, Issue 12 2006Joel M. Hall Chemiluminescence from the OH(A , X) transition near 307 nm is a commonly used diagnostic in combustion applications such as flame chemistry, shock-tube experiments, and reacting-flow visualization. Although absolute measurements of OH(X) concentrations are well defined, there is no elementary relation between emission from the electronically excited state (OH*) and its absolute concentration. Thus, to enable quantitative emission measurements, a kinetics model has been assembled and optimized to predict OH* formation and quenching at combustion conditions. Shock-tube experiments were conducted in mixtures of H2/O2/Ar, CH4/O2/Ar, and CH4/H2/O2/Ar with high levels of argon dilution (>98%). Elementary reactions to model OH*, along with initial estimates of their rate coefficients, were taken from the literature. The important formation steps follow: (R0) (R1) Sensitivity analyses were performed to identify experimental conditions under which the shape of the measured OH* profiles and the magnitude of the OH* emission would be sensitive to the formation reactions. A fitting routine was developed to express the formation rate parameters as a function of a single rate, k1 at the reference temperature (1490 K). With all rates so expressed, H2/CH4 mixtures were designed to uniquely determine the value of k1 at the reference temperature, from which the remaining rate parameters were calculated. Quenching rates were fixed at their literature values. The new model predicts the experimental data over the range of conditions studied and can be used to calibrate the emission diagnostic for other applications, such as measurements in real combustion environments, containing higher order hydrocarbon fuels and lower levels of dilution in air. © 2006 Wiley Periodicals, Inc. Int J Chem Kinet 38: 714,724, 2006 [source] Practical aspects of PARAFAC modeling of fluorescence excitation-emission dataJOURNAL OF CHEMOMETRICS, Issue 4 2003C. M. Andersen Abstract This paper presents a dedicated investigation and practical description of how to apply PARAFAC modeling to complicated fluorescence excitation,emission measurements. The steps involved in finding the optimal PARAFAC model are described in detail based on the characteristics of fluorescence data. These steps include choosing the right number of components, handling problems with missing values and scatter, detecting variables influenced by noise and identifying outliers. Various validation methods are applied in order to ensure that the optimal model has been found and several common data-specific problems and their solutions are explained. Finally, interpretations of the specific models are given. The paper can be used as a tutorial for investigating fluorescence landscapes with multi-way analysis. Copyright © 2003 John Wiley & Sons, Ltd. [source] Plant-mediated nitrous oxide emissions from beech (Fagus sylvatica) leavesNEW PHYTOLOGIST, Issue 1 2005Mari Pihlatie Summary ,,Nitrous oxide (N2O) emission estimates from forest ecosystems are based currently on emission measurements using soil enclosures. Such enclosures exclude emissions via tall plants and trees and may therefore underestimate the whole-ecosystem N2O emissions. ,,Here, we measured plant-mediated N2O emissions from the leaves of potted beech (Fagus sylvatica) seedlings after fertilizing the soil with 15N-labelled ammonium nitrate (15NH415NO3), and after exposing the roots to elevated concentrations of N2O. ,,Ammonium nitrate fertilization induced N2O + 15N2O emissions from beech leaves. Likewise, the foliage emitted N2O after beech roots were exposed to elevated concentrations of N2O. The average N2O emissions from the fertilization and the root exposure experiments were 0.4 and 2.0 µg N m,2 leaf area h,1, respectively. Higher than ambient atmospheric concentrations of N2O in the leaves of the forest trees indicate a potential for canopy N2O emissions in the forest. ,,Our experiments demonstrate the existence of a previously overlooked pathway of N2O to the atmosphere in forest ecosystems, and bring about a need to investigate the magnitude of this phenomenon at larger scales. [source] Spectroscopy and Photoreactivity of Trichochromes: Molecular Components of Pheomelanins,PHOTOCHEMISTRY & PHOTOBIOLOGY, Issue 1 2006John D. Simon ABSTRACT The trichochromes are a class of small molecules present in pheomelanin (the red melanin) and absent in eumelanin (the black melanin). Herein trichochrome F (TF) and decarboxy-trichochrome C (dTC) are examined. Both trichochromes are characterized by a visible absorption band, which is shown to be the result of overlapping transitions of the cis and trans isomers. The temperature dependence of the absorption spectrum of dTC suggests the additional presence of equilibrium between the enol and keto forms of the molecule. These conclusions are supported by ground-state energies of these isomers obtained using a continuum solvation model. Near-infrared emission measurements were not able to detect photoproduction of 1O2, and spin-trapping experiments revealed formation of O2*- . DNA nicking assays also revealed a low level of light-induced aerobic activity of dTC, suggesting a quantum efficiency of at most 5 × 10 -6 for the photo-generation of O2*- . These results are consistent with pump-probe optical experiments, which reveal efficient and nearly complete ground-state recovery within a few picoseconds of excitation. Both trichochromes are efficient quenchers of 1O2, exhibiting a bimolecular rate constant comparable with vitamin C. These results suggest that trichochromes could serve a protective role in pheomelanin pigments. [source] Supramolecular Assembly of 2,7-Dimethyldiazapyrenium and Cucurbit[8]uril: A New Fluorescent Host for Detection of Catechol and DopamineCHEMISTRY - A EUROPEAN JOURNAL, Issue 23 2005Vladimir Sindelar Dr. Abstract The formation of a highly stable inclusion complex between 2,7-dimethyldiazapyrenium (Me2DAP2+) and the cucurbit[8]uril host (CB8) was demonstrated by X-ray crystallography; MALDI-TOF mass spectrometry; and 1H NMR, electronic absorption, and emission spectroscopy. The equilibrium association constant was determined to be 8.9(±0.2)×105 L,mol,1 from UV-visible data and 8.4(±1.5)×105 L,mol,1 from fluorescence data. The Me2DAP2+,CB8 inclusion complex acted as a host to bind compounds containing aromatic ,-donor moieties (D), such as catechol and dopamine. This point was demonstrated by 1H NMR spectroscopy, and electrochemical and emission measurements. Fluorescence detection of the Me2DAP2+,D,CB8 ternary complexes was evident in aqueous solution and on the surface of silica particles, to which fluorescent diazapyrenium units had been covalently immobilized. [source] | |||||||||||||