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Hydroxyl radical measurement in atmospheric pressure dimethyl ether-air laminar premixed flat flame using tunable diode laser absorption spectroscopy
Nevrlý, V. ; Dostál, Michal ; Bitala, P. ; Zelinger, Zdeněk ; Suchánek, Jan ; Válek, V. ; Klečka, V. ; Kubát, Pavel ; Engst, Pavel ; Vašinek, M. ; Wild, J.
Spectroscopic detection of hydroxyl (OH) radical and determination of its concentration in flames have an elusive history and considerable influence on combustion research. Electronic transitions in ultraviolet spectral region were extensively studied in this context and until recent time chemiluminescence or laser induced fluorescence of excited hydroxyl (OH*) radical is broadly used for absolute concentration and temperature measurement in flames.\nHowever, number densities of molecular species and population of relevant quantum levels in ground electronic state can be directly estimated from intensities of absorption lines observed by probing rovibrational transitions in infrared spectral region. Application of near-infrared tunable diode laser absorption spectroscopy (NIR-TDLAS) for the given purpose was demonstrated in an earlier work of Aizawa et al. [1]. Following his pioneering studies summarized in [2], we further explored feasibility of NIR-TDLAS (especially 2f-WMS technique) for monitoring minor species within combustion experiments particularly when dealing with dimethyl ether (DME) flames. Here we report our first results of NIR-TDLAS measurements focused on hydroxyl radical detection in laminar premixed flame burning DME-air mixture under fuel-lean conditions.
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Wavelength modulation spectroscopy for multicomponent ana-lytics of biomass burning tracers
Dostál, Michal ; Válek, V. ; Suchánek, Jan ; Kristlová, E. ; Roupcová, P. ; Zelinger, Zdeněk ; Nevrlý, Václav ; Bitala, P. ; Vašinek, M. ; Kubát, Pavel ; Ferus, Martin ; Civiš, Svatopluk
The potential of Tunable Diode Laser Absorption Spectroscopy (TDLAS) for monitoring of several species produced by biomass burning is in focus of this work. The infrared spectra of selected molecules (HCOOH, C2H2, CH3CN, N2O, CH3OH, CH3COCH3) are measured in laboratory conditions and the selectivity and of this method is demonstrated.
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Transjugular intrahepatic portosystemic shunt: long-term patency in patients with hypercoagulation disorder
Renc, Ondřej ; Krajina, Antonín (advisor) ; Válek, Vlastimil (referee) ; Lata, Jan (referee)
Transjugular intrahepatic portosystemic shunt: long-term patency in patients with hypercoagulation disorder Aim: To retrospectively evaluate the efficacy and long-term patency of transjugular intrahepatic portosystemic shunt (TIPS) in patients with hepatic vein thrombosis due to hypercoagulation disorder. Material and method: In years 1992 - 2011, totally 38 patients with hepatic vein thrombosis resistant to medical therapy underwent TIPS creation in our department. We treated 9 males and 29 females, age 13 - 76 years (median 33 years), 6 patients were children. The underlying thrombophilic state was confirmed in 84,2 % of treated patients. The Budd-Chiari syndrome was acute in 6, subacute in 18 and chronic in 14 cases. Ascites was indication for TIPS in 31 patients, liver failure in 5 and gastrointestinal bleeding in 2 persons. All the procedures were performed in analgosedation or under general anestesia using standard technique. In 17 patients, we implanted non-covered stent or combination of non-covered and covered stents during TIPS creation, in the other 21 patients only the TIPS dedicated covered stents had been used. TIPS patency during follow-up after the procedure was based on regular ultrasonographic, clinical and laboratory examinations. In case of shunt dysfunction, a reintervention was...
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