| 1. |
- Kiefer, J., et al.
(author)
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OH-thermometry using laser polarization spectroscopy and laser-induced fluorescence spectroscopy in the OH A-X (1,0) band
- 2009
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In: Journal Of Raman Spectroscopy. - : Wiley. - 0377-0486 .- 1097-4555. ; 40:7, s. 828-835
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Conference paper (peer-reviewed)abstract
- Laser-induced fluorescence (LIF) and polarization spectroscopy (PS) is used for OH-thermometry utilizing the off-diagonal A-X (1,0) band. Both techniques are used simultaneously in order to allow a comparison of the results. For deriving temperature information from the spectra, three methods are employed: (1) a contour fit method comparing experimental and calculated spectra, (2) spectral fitting of a single highly resolved spectral line and (3) a two-line intensity ratio approach. In general, both spectroscopic techniques gave similar results. The high-resolution approach (2) did not deliver reasonable results in our experiments. The most accurate but also most time consuming method was the contour fit (1). For future two-dimensional temperature measurements, the 2-line-method (3) was identified to be the method of choice. The present study contains, to the best of our knowledge, the first polarization spectroscopic study in the A-X (1,0) band of OH. Copyright (C) 2009 John Wiley & Sons, Ltd.
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| 2. |
- Buldyreva, J, et al.
(author)
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Linewidth modelling of C2H2-N-2 mixtures tested by rotational CARS measurements
- 2006
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In: Journal of Raman Spectroscopy. - : Wiley. - 1097-4555 .- 0377-0486. ; 37:6, s. 647-654
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Journal article (peer-reviewed)abstract
- The acetylene-nitrogen system is investigated in a combined theoretical and experimental effort in view of its thermometry applications. Accurate values of the rotational Raman linewidths of acetylene are of crucial importance for the computation of spectra from rotational coherent anti-Stokes Raman scattering (CARS) used for temperature and concentration evaluations. Since the direct measurements of these linewidths are not available, they are rigorously calculated by a semi-classical Robert-Bonamy formalism employing exact trajectories. The computed linewidths are used as input parameters in the theoretical spectra simulation, which is also improved by the inclusion of an interbranch interference with coherent Stokes Raman scattering (CSRS). These theoretical spectra are used to evaluate the temperature from experimental CARS spectra of acetylene-nitrogen mixtures recorded in the pressure range 0.1-0.6 MPa. The new linewidths (NLWs) and the CSRS interference inclusion result in a clear improvement of spectral fitting as well as in reasonable values of evaluated temperatures. Copyright (c) 2006 John Wiley & Sons, Ltd.
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| 3. |
- Kiefer, J, et al.
(author)
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Planar laser-induced fluorescence of HCO for instantaneous flame front imaging in hydrocarbon flames
- 2009
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In: Proceedings of the Combustion Institute. - : Elsevier BV. - 1540-7489. ; 32, s. 921-928
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Journal article (peer-reviewed)abstract
- The detection of the formyl radical (HCO) is of great interest in the field of combustion research since it can provide information about the local heat release (HR) rate which is a key parameter in the understanding of combustion processes. Unfortunately, due to the low signal level, HCO planar laser-induced fluorescence (PLTF) has so far not been applicable for single-shot imaging, which is necessary in particular for studying turbulent flames. In the present paper for the first time, to the best of our knowledge, single-shot PLIF imaging of HCO in flames is demonstrated by employing-a multimode frequency-tripled alexandrite laser. Oil the basis of long pulse duration along with a spectrally broad bandwidth enabling multi-line excitation a sufficient signal-to-noise ratio is achieved. In detail, excitation in the B-X system around 258.69 nm is applied and subsequent fluorescence detection in the spectral range 300-400 nm is performed. A series of experiments concerning spectral interferences, saturation behavior and the influence of flame stoichiometry (in the range phi = 0.6-2) have been conducted. Two typical fuels have been employed: methane (CH4) as conventional hydrocarbon as well as dimethyl ether (DME) as modern bio fuel. Single-shot HCO imaging is finally demonstrated in a laminar DME/air Bunsen flame and in a slightly turbulent methane/oxygen welding torch flame. The results indicate that the developed HCO PLIF technique offers a strong potential for improved flame Studies particularly in turbulent flames, In general, the approach to employ laser sources with reasonably broader bandwidth and longer pulse duration compared to conventional Nd:YAG pumped systems for PLIF will open up new possibilities in the field of Combustion diagnostics. (c) 2009 The Combustion Institute. Published by Elsevier file. All rights reserved.
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| 4. |
- Peacock, Christopher S, et al.
(author)
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Comparative genomic analysis of three Leishmania species that cause diverse human disease.
- 2007
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In: Nature Genetics. - : Springer Science and Business Media LLC. - 1061-4036 .- 1546-1718. ; 39:7, s. 839-847
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Journal article (peer-reviewed)abstract
- Leishmania parasites cause a broad spectrum of clinical disease. Here we report the sequencing of the genomes of two species of Leishmania: Leishmania infantum and Leishmania braziliensis. The comparison of these sequences with the published genome of Leishmania major reveals marked conservation of synteny and identifies only 200 genes with a differential distribution between the three species. L. braziliensis, contrary to Leishmania species examined so far, possesses components of a putative RNA-mediated interference pathway, telomere-associated transposable elements and spliced leader–associated SLACS retrotransposons. We show that pseudogene formation and gene loss are the principal forces shaping the different genomes. Genes that are differentially distributed between the species encode proteins implicated in host-pathogen interactions and parasite survival in the macrophage.
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