New measurements of the absolute absorption cross-sections of ozone at 294 and 223 K in the 310-350 nm spectral range

Absolute measurements of the absorption cross-sections of ozone in the 310-350 nm range (Huggin's system) were carried out at 294 and 223 K with high resolution. Our results — lower than all results known to date — are, within a coefficient, in very close agreement with the (relative) values obtained recently by A. M. Bass and R. J. Paur with a resolution similar to that used in this work.Les mesures absolues des sections efficaces de l'ozone dans le domaine 310-350 nm (système de Huggins) ont été réalisées à 294 K et 223 K à haute résolution. Les résultats proposés — en baisse par rapport à l'ensemble des données connues — sont, à un coefficient près, en très bon accord avec les valeurs (relatives) obtenues récemment par A. M. Bass et R. J. Paur avec une résolution analogue à celle de ce travail

Sections efficaces absolues de l'ozone à 298 K aux longueurs d'onde de la lampe au mercure : étude critique des données expérimentales existantes

Considering the importance of the knowledge of the values for the absorption cross-sections of ozone at the mercury lamp wavelengths, specially for the calibration of relative measurements, a critical review of data given by previous workers is presented : it shows a good agreement for the results obtained at 289.36, 296.73 and 302.15 nm, and it needs to reconsider the result generally used up to now at 253.65 nm (about 3 % too high).En raison de l'importance que présente la connaissance des sections efficaces de l'ozone aux longueurs d'onde de la lampe au mercure, en particulier pour le calibrage des mesures relatives, une étude critique des données disponibles dans la littérature est effectuée : elle montre une bonne cohérence entre les résultats connus à 289,36, 296,73 et 302,15 nm et conduit à réviser le résultat admis généralement à 253,65 nm (baisse de 3 % environ)

Study of C

To study the reaction of peroxy radicals, we have set up the experimental technique of modulated photolysis. In this work, the UV absorption spectrum of C2H5O2 and the kinetics of its self-reaction have been investigated. Experiments have been made, firstly to check our apparatus in comparing our results with previous measurements, then to obtain new information in a temperature range where conflicting results were obtained by previous authors. The room temperature rate constant kobs has a value of ( 10.3+/-0.5) × 10-14 cm3. molecule-1.s-1. In the range [253-363] K, the Arrhenius expression is : kobs = 1.56 × 10-13 × exp(-128/T) ( cm3.molecule-1.s-1 ). The real rate constant of this reaction was determined from the experimental results of kobs and from the branching ratio. The Arrhenius expression of real rate is :kreal = 6.4 × 10-14 × exp (-23 / T) (cm3.molecule-1 s-1

ROTATIONAL ANALYSIS OF THE NEAR INFRARED SINGLET-TRIPLET ELECTRONIC SPECTRUM OF OZONE

Author Institution: Laboratoire de Spectrom\'{e}trie lonique et Mol\'{e}culaire (associ\'{e} au CNRS U.M.R. 5579), Universit\'{e} Claude Bernard Lyon; Laboratoire de Chimie-Physique, Facult\'{e} des Sciences de Reims; Department of Chemistry, University of Wisconsin-ParksideHigh Resolution Fourier Transform Infrared Spectrometry was used to study the rotational fine structure of the lowest energy singlet-triplet electronic spectrum of ozone, $^{16}O_{3}$ and $^{18}O_{3}$ near $9300 cm^{-1}$. With a near pure case (b) coupling model, approximately 100 lines were assigned in the spectrum of $^{16}O_{3}$. A combined least-squares/band contour analysis yielded an overall standard deviation of $0.045 cm^{-1}$. The fit to the ${^{18}}O_{3}$ spectrum used approximately 30 lines and gave a slightly higher overall standard deviation. The rotational analysis has established that the upper state is ${^{3}}A_{2}$ in agreement with recent theoretical calculations. Numerous perturbations are observed in the spectrum of both isotopomers and limited our least-squares fit to the three rotational constants, the symmetric top distortion constants, the three spin-rotation constants and the alpha spin-spin constant. The talk will feature an overview of the rotational analysis along with a brief discussion of the perturbations seen in the spectrum

Regulation of apoptosis by the p8/prothymosin α complex

p8 is a small-stress protein involved in several cellular functions including apoptosis. To identify its putative partners, we screened a HeLa cDNA library by using the two-hybrid technique and found that p8 binds the antiapoptotic protein prothymosin α (ProTα). Fluorescence spectroscopy, circular dichroism, and NMR spectroscopy showed that p8 and ProTα formed a complex. Binding resulted in important changes in the secondary and tertiary structures of the proteins. Because p8 and ProTα form a complex, they could act in concert to regulate the apoptotic cascade. We induced apoptosis in HeLa cells by staurosporine treatment and monitored the effects of knocking down p8 and/or ProTα or overexpressing p8 and/or ProTα on caspase 3/7 and 9 activities and on cell death. Transfecting ProTα or p8 small interfering RNAs increased the activities of both caspases and the number of apoptotic nuclei. However, transfecting both small interfering RNAs resulted in no further increase. Overexpressing p8 or ProTα did not alter caspase activities, whereas overexpressing both resulted in a significant reduction of caspase activities. These results strongly suggest that the antiapoptotic response of HeLa cells upon staurosporine treatment requires expression of both p8 and ProTα