A. Mellouki - Profile on Academia.edu (original) (raw)

Papers by A. Mellouki

Research paper thumbnail of Simple and Reversible Transformation of an APCI/MS/MS Into an Aerosol Mass Spectrometer: Development and Characterization of a New Inlet

Aerosol Science and Technology, 2008

The inlet of a commercial atmospheric pressure chemical ionization-mass spectrometer (APCI/MS/MS)... more The inlet of a commercial atmospheric pressure chemical ionization-mass spectrometer (APCI/MS/MS) has been modified to transform it into an aerosol mass spectrometer, named TD-API-AMS. The new inlet consists in a charcoal denuder (to trap gas phase VOCs and SVOCs) followed by the thermal-desorption unit of the APCI source. Thermal desorption and APCI were chosen because they avoid sample denaturizing while keeping good time resolution. The objectives of this paper are (1) to describe the simple and reversible modifications of the commercial APCI inlet allowing its use as an aerosol mass spectrometer and (2) to characterize the performances of this modified inlet. These performances are characterized in term of efficiency of (i) gas phase organic compounds removal, (ii) particle transmission, and (iii) particle volatilization in the thermal-desorption unit. The characterization was conduced with secondary organic aerosol (SOA) produced from the ozonolysis of α-pinene and 2-buten-1-ol in a continuous flow reactor. The results show a denuder gas phase trapping efficiency higher than 93 ± 3% while the particle transmission efficiency was nearly 100% in particle number, but decreased to as little as 85% in total particle volume. This result highlights a shift of the particle distribution towards the fine particles occurring through the denuder, due to a modification of the gas-particle equilibrium. The inlets' characterization has also shown a particle volatilization efficiency higher than 90% (in volume).

Research paper thumbnail of Characteristics and sources of nitrous acid in an urban atmosphere of northern China: Results from 1-yr continuous observations

Atmospheric Environment, 2018

Nitrous acid (HONO) is a key reservoir of the hydroxyl radical (OH) and plays a central role in t... more Nitrous acid (HONO) is a key reservoir of the hydroxyl radical (OH) and plays a central role in the atmospheric chemistry. To understand the sources and impact of HONO in the polluted atmosphere of northern China, continuous measurements of HONO and related parameters were conducted from September 2015 to August 2016 at an urban site in Ji'nan, the capital city of Shandong province. HONO showed well-defined seasonal and diurnal variation patterns with clear wintertime and nighttime concentration peaks. Elevated HONO concentrations (e.g., over 5 ppbv) were frequently observed with a maximum value of 8.36 ppbv. The HONO/NO X ratios of direct vehicle emissions varied in the range of 0.29%-0.87%, with a mean value of 0.53%. An average NO 2-to-HONO nighttime conversion frequency (k het) was derived to be 0.0068±0.0045 h-1 from 107 HONO formation cases. A detailed HONO budget analysis suggests an unexplained daytime missing source of 2.95 ppb h-1 in summer, which is about seven times larger than the homogeneous reaction of NO with OH. The effect of HONO on OH production was also quantified. HONO photolysis was the uppermost source of local OH radical throughout the daytime. This study provides the year-round

Research paper thumbnail of by Laser Photolysis-Laser Induced Fluorescence

by Laser Photolysis-Laser Induced Fluorescence

reactions play a very important role in air pollution. For the majority of chemical compounds of ... more reactions play a very important role in air pollution. For the majority of chemical compounds of theatmosphere, the reaction with OH radicals is an intermediate one, part of a long chain reaction. A Laser Photolysis-LaserInduced Fluorescence (LP-LIF) technique has been used to study OH reaction kinetics with dioxane. The apparatus consistsof two synchronized pulsed laser systems, a six cross flow I

Research paper thumbnail of Trends in atmospheric photodissociation rates of selected carbonyl compounds

Trends in atmospheric photodissociation rates of selected carbonyl compounds

Research paper thumbnail of Photocatalytic abatement results from a model street canyon

Environmental Science and Pollution Research, 2015

Your article is protected by copyright and all rights are held exclusively by Springer-Verlag Ber... more Your article is protected by copyright and all rights are held exclusively by Springer-Verlag Berlin Heidelberg. This e-offprint is for personal use only and shall not be selfarchived in electronic repositories. If you wish to self-archive your article, please use the accepted manuscript version for posting on your own website. You may further deposit the accepted manuscript version in any repository, provided it is only made publicly available 12 months after official publication or later and provided acknowledgement is given to the original source of publication and a link is inserted to the published article on Springer's website. The link must be accompanied by the following text: "The final publication is available at link.springer.com".

Research paper thumbnail of Reaction of Cl Atoms with C 6 F 13 CH 2 OH, C 6 F 13 CHO, and C 3 F 7 CHO

Reaction of Cl Atoms with C 6 F 13 CH 2 OH, C 6 F 13 CHO, and C 3 F 7 CHO

The Journal of Physical Chemistry A, 2006

The Cl atom initiated oxidation of C(6)F(13)CH(2)OH, C(6)F(13)CHO, and C(3)F(7)CHO was investigat... more The Cl atom initiated oxidation of C(6)F(13)CH(2)OH, C(6)F(13)CHO, and C(3)F(7)CHO was investigated at 298 K and 1000 mbar pressure of air in a photoreactor using in situ Fourier transform infrared (FTIR) analysis. The rate coefficient for the reaction Cl + C(6)F(13)CH(2)OH (reaction 2) was measured using a relative method: k(2) = (6.5 +/- 0.8) x 10(-13) cm(3) molecule(-1) s(-1). C(6)F(13)CHO was detected as the major primary product, while CO and CF(2)O were found to be the major secondary products. A fitting procedure applied to the concentration-time profiles of C(6)F(13)CHO provided a production yield of (1.0 +/- 0.2) for this aldehyde in reaction 2, and the rate coefficient for the reaction Cl + C(6)F(13)CHO (reaction 4) was k(4) = (2.8 +/- 0.7) x 10(-12) cm(3) molecule(-1) s(-1). A high CO yield observed in the oxidation of C(6)F(13)CH(2)OH, (52 +/- 1)%, is attributed to the Cl atom initiated oxidation of C(6)F(13)CHO. High CO yields, (61 +/- 2)% and (85 +/- 5)%, were also measured in the Cl atom initiated oxidation of C(3)F(7)CHO in air and nitrogen, respectively. These high CO yields suggest the occurrence of a decomposition reaction of the perfluoroacyl, C(6)F(13)CO, and C(3)F(7)CO radicals to form CO which will compete with the combination reaction of these radicals with oxygen to form perfluoroacyl peroxy radicals in the presence of air. The latter radicals C(n)F(2)(n)(+1)CO(O)(2) (n = 6-12), through their reaction with HO(2) radicals, are currently considered as a possible source of persistent perfluorocarboxylic acids which have been detected in the environment. The consequences of the present results would be a reduction of the strength of this potential source of carboxylic acids in the atmosphere.

Research paper thumbnail of Kinetic Studies on the Reactions of Hydroxyl Radicals with Cyclic Ethers and Aliphatic Diethers

The Journal of Physical Chemistry A, 2006

Bras: Kinetic Studies on the Reactions of Hydroxyl Radicals with Cyclic Ethers and Aliphatic Diet... more Bras: Kinetic Studies on the Reactions of Hydroxyl Radicals with Cyclic Ethers and Aliphatic Diethers Two errors and one omission have been found in the original article. 1 Page 1501: In Table 1, the reference compound used for 1,3dioxepane was in fact (CH 3) 2 CHOCH 2 CH 2 OH and not (CH 3) 2-CH(OH)CH 2 OCH 3. The rate coefficient for reaction of OH with (CH 3) 2 CHOCH 2 CH 2 OH (k 5) was 21.0 × 10-12 cm 3 molecule-1 s-1 , as reported by Porter et al. 2 The reported value of k 4 /k 5 for 1,3-dioxepane, 0.58

Research paper thumbnail of A tunable diode laser absorption spectrometer for formaldehyde atmospheric measurements validated by simulation chamber instrumentation

Journal of Environmental Sciences, 2012

A tunable diode laser absorption spectrometer (TDLAS) for formaldehyde atmospheric measurements h... more A tunable diode laser absorption spectrometer (TDLAS) for formaldehyde atmospheric measurements has been set up and validated through comparison experiments with a Fourier transform infrared spectrometer (FTIR) in a simulation chamber. Formaldehyde was generated in situ in the chamber from reaction of ethene with ozone. Three HCHO rovibrational line intensities (at 2909.71, 2912.09 and 2914.46 cm-1) possibly used by TDLAS were calibrated by FTIR spectra simultaneously recorded in the 1600-3200 cm-1 domain during ethene ozonolysis, enabling the on-line deduction of the varying concentration for HCHO in formation. The experimental line intensities values inferred confirmed the calculated ones from the updated HITRAN database (Rothman et al., 2009, based on Perrin et al., 2009). In addition, the feasibility of stratospheric in situ HCHO measurements using the 2912.09 cm-1 line was demonstrated. The TDLAS performances were also assessed, leading to a 2 detection limit of 88 ppt in volume mixing ratio with a response time of 60 s at 30 Torr and 294 K for 112 m optical path. As part of this work, the room-temperature rate-2-constant of this reaction and the HCHO formation yield were found to be in excellent agreement with the compiled literature data.

Research paper thumbnail of Photolysis of Trichloronitromethane (Chloropicrin) under Atmospheric Conditions

Zeitschrift für Physikalische Chemie, 2010

An experimental investigation on the photolysis of the pesticide chloropicrin, (trichloronitromet... more An experimental investigation on the photolysis of the pesticide chloropicrin, (trichloronitromethane, CCl3NO2), under atmospheric conditions was carried out at the outdoor European Photoreactor, (EUPHORE), in Valencia, Spain. The photodissociation rate coefficient, J obs(CCl3NO2), was determined directly under sunlight conditions during spring and summer months. Values in the range J obs(CCl3NO2) = (3.9–5.1)×10−5 s−1 were obtained, corresponding to photolysis lifetimes of 7.1–5.4 hours. Absorption cross-sections for chloropicrin were determined over the wavelength range 260–370 nm, and together with the measured solar flux intensity, were used to calculate the maximum photolysis rate for chloropicrin, J max. Comparison of the observed photolysis rate with the calculated maximum photolysis rate showed that the effective quantum yield of photodissociation, Φ = J obs(CCl3NO2)/J max, was 0.94±0.08. Photolysis of chloropicrin in air or nitrogen gave phosgene as the major carbon-containi...

Research paper thumbnail of Rate coefficients for the reaction of OH with HONO between 298 and 373 K

International Journal of Chemical Kinetics, 1992

The rate coefficients for the reaction of O H with CHJF, CHF3, CzHsF, C~H~F S , and CSHZFlO were ... more The rate coefficients for the reaction of O H with CHJF, CHF3, CzHsF, C~H~F S , and CSHZFlO were measured at temperatures between 232 and 378 K using the pulsed laser photolysis-laser-induced fluorescence technique. The rate coefficients for the reaction of O(lD) with the above molecules and CHzFz were measured at room temperature using time-resolvedvacuum-UV atomic resonance fluorescence detection of Ot3P). The atmospheric lifetimes needed for the evaluation of global warming potentials were calculated for all six molecules using a one-dimensional atmospheric model using the kinetic data obtained in the present study.

Research paper thumbnail of Kinetics of OH and Cl reactions with a series of aldehydes

Kinetics of OH and Cl reactions with a series of aldehydes

International Journal of Chemical Kinetics, 2000

The rate constants for the reactions of the OH radicals with a series of aldehydes have been meas... more The rate constants for the reactions of the OH radicals with a series of aldehydes have been measured in the temperature range 243–372 K, using the pulsed laser photolysis-pulsed laser induced fluorescence method. The obtained data for propanaldehyde, iso-butyraldehyde, tert-butyraldehyde, and n-pentaldehyde were as follows (in cm3 molecule−1 s−1): (a) in the Arrhenius form: (5.3 ± 0.5) × 10−12 exp[(405 ± 30)/T], (7.3 ± 1.9) × 10−12 exp[(390 ± 78)/T], (4.7 ± 0.8) × 10−12 exp[(564 ± 52)/T], and (9.9 ± 1.9) × 10−12 exp[(306 ± 56)/T]; (b) at 298 K: (2.0 ± 0.3) × 10−11, (2.6 ± 0.4) × 10−11, (2.7 ± 0.4) × 10−11, and (2.8 ± 0.2) × 10−11, respectively. In addition, using the relative rate method and alkanes as the reference compounds, the room-temperature rate constants have been measured for the reactions of chlorine atoms with propanaldehyde, iso-butyraldehyde, tert-butyraldehyde, n-pentaldehyde, acrolein, and crotonaldehyde. The obtained values were (in cm3 molecule−1 s−1): (1.4 ± 0.3) × 10−10, (1.7 ± 0.3)10−10, (1.6 ± 0.3) × 10−10, (2.6 ± 0.3) × 10−10, (2.2 ± 0.3) × 10−10, and (2.6 ± 0.3) × 10−10, respectively. The results are presented and discussed in terms of structure-reactivity relationships and atmospheric importance. © 2000 John Wiley & Sons, Inc. Int J Chem Kinet 32: 676–685, 2000

Research paper thumbnail of Abstracts of the 6th FECS Conference 1998 Lectures

Abstracts of the 6th FECS Conference 1998 Lectures

Environmental Science and Pollution Research, 1998

International audienc

Research paper thumbnail of Evaluated kinetic and photochemical data for atmospheric chemistry: Volume VI – heterogeneous reactions with liquid substrates

Atmospheric Chemistry and Physics, 2013

This article, the sixth in the ACP journal series, presents data evaluated by the IUPAC Task Grou... more This article, the sixth in the ACP journal series, presents data evaluated by the IUPAC Task Group on Atmospheric Chemical Kinetic Data Evaluation. It covers the heterogeneous processes involving liquid particles present in the atmosphere with an emphasis on those relevant for the upper troposphere/lower stratosphere and the marine boundary layer, for which uptake coefficients and adsorption parameters have been presented on the IUPAC website since 2009. The article consists of an introduction and guide to the evaluation, giving a unifying framework for parameterisation of atmospheric heterogeneous processes. We provide summary sheets containing the recommended uptake parameters for the evaluated processes. The experimental data on which the recommendations are based are provided in data sheets in separate appendices for the four surfaces considered: liquid water, deliquesced halide salts, other aqueous electrolytes and sulfuric acid.

Research paper thumbnail of Regional climate variability and its impacts in the Mediterranean area

PREFACE xii are needed. Further, it is clear that long-term monitoring of various calculating emi... more PREFACE xii are needed. Further, it is clear that long-term monitoring of various calculating emissions, atmospheric composition, and transport in and out of the region. Observations of processes that are unique to this region

Research paper thumbnail of Scientific Assessment of Ozone Depletion: 2010

Ajavon, Ayité-Lo Université de Lomé Togo Andersen, Stephen O. Environmental Protection Agency USA... more Ajavon, Ayité-Lo Université de Lomé Togo Andersen, Stephen O. Environmental Protection Agency USA Austin, John NOAA Geophysical Fluid Dynamics Laboratory USA Bais, Alkiviadis F. Aristotle University of Thessaloniki Greece Baldwin, Mark NorthWest Research Associates, Inc. USA Beig, Gufran Indian Institute of Tropical Meteorology India Björn, Lars Olof Lund University Sweden Bodeker, Greg National Institute of Water & Atmospheric Research New Zealand Braathen, Geir World Meteorological Organization Switzerland Burrows, John University of Bremen Germany Chanin, Marie-Lise Service d'Aeronomie du CNRS France Chipperfield, Martyn University of Leeds UK Clerbaux, Catherine Service d'Aeronomie du CNRS France Cunnold, Derek Georgia Institute of Technology USA Dameris, Martin German Aerospace Center (DLR) Institut für Physik der Atmosphäre Germany

Research paper thumbnail of New Measurements of Methyl Ethyl Ketone (MEK) Photolysis Rates and Their Relevance to Global Oxidative Capacity

New Measurements of Methyl Ethyl Ketone (MEK) Photolysis Rates and Their Relevance to Global Oxidative Capacity

Research paper thumbnail of Prise en charge chirurgicale robotique d’un adénome de prostate compliqué d’un volumineux diverticule, technique et complications

Prise en charge chirurgicale robotique d’un adénome de prostate compliqué d’un volumineux diverticule, technique et complications

Progrès en Urologie

Objectif L’adenomectomie voix haute (AVH) assistee par robot represente une alternative chirurgic... more Objectif L’adenomectomie voix haute (AVH) assistee par robot represente une alternative chirurgicale emergeante pour les hypertrophies benignes de prostate (HBP) de haut volume. L’approche transvesicale pourrait permettre de traiter dans le meme temps operatoire d’eventuelles complications diverticulaires associees. Nous en decrivons la technique chirurgicale, les resultats et le risque de complications identifiees par assistance video. Methodes Un patient de 70 ans, sans antecedent chirurgical, presentant une HBP symptomatique de 80 g compliquee d’un diverticule de 350cc, a beneficie d’une AVH robotique avec diverticulectomie synchrone par voie transvesicale. L’intervention etait realisee avec un robot Da-Vinci X® surgical system(intuitive Surgical Inc, Sunnyvale, CA, USA) 4 bras et 2 instruments assistants. Les trocarts places en transperitoneal suivaient une ligne convexe en haut en sus-ombilical, apres open-coelioscopique. Les instruments assistants etaient en pararectal et fosse iliaque gauche. Le robot etait a droite du patient place en Trendelenburg −30°, jambes a l’horizontale, sonde vesicale Ch18 en place. L’intervention etait enregistree pour relecture, les temps operatoires controles. Resultats L’intervention a ete realisee en un seul temps en 4 h, temps de console de 3h40. L’HBP et le diverticule pesaient 62 g et 110 g, respectivement. Les suites operatoires etaient marquees par une complication precoce de douleurs abdominales gauches irradiant dans le dos et une elevation de la creatininemie a 135 μmol/L. Un TDM abdomino-pelvien injecte a J2 revelait une dilatation pyelo-calicielle bilaterale predominant a gauche avec urinome traitee par nephrostomie gauche a J2. Le controle video de l’enregistrement permit d’identifier une section ureterale gauche lors de la dissection a la 17eme minute. Une re-implantation uretero-vesicale gauche par mini-laparotomie a ete realisee. Le controle mictionnel a 3 mois etait satisfaisant, IPSS 4, Qol 1 avec un residu post-mictionnel reduit mais significatif de 244 mL. Conclusion L’adenomectomie avec diverticulectomie par voie transvesicale robotique en un temps est realisable. L’assistance video post-operatoire permet le controle et l’identification des complications. L’enregistrement systematique des interventions pourrait beneficier a la securisation des pratiques.

Research paper thumbnail of Atmospheric degradation of pyridine: UV absorption spectrum and reaction with OH radicals and O 3

Chemical Physics Letters

The UV absorption spectrum of pyridine and its gas phase reactions with OH radicals and O 3 were ... more The UV absorption spectrum of pyridine and its gas phase reactions with OH radicals and O 3 were investigated. UV absorption cross-sections were determined by using a D 2-lamp system in the range 200-350 nm. The kinetic studies were carried out at room temperature and atmospheric pressure of purified air. The rate coefficient for the reaction of pyridine with OH was determined relative to that with acetone while that with O 3 was measured under pseudo first order conditions. The rate coefficients obtained are (in cm 3 molecule-1 s-1): k(OH+Pyridine) = (5.40 ± 0.80) ×10-13 and k(O 3 +Pyridine) = (3.28 ± 1.70) × 10-20 .

Research paper thumbnail of ChemInform Abstract: Discharge Flow Kinetic Study of the Reactions of NO3 with Br, BrO, HBr, and HCl

ChemInform Abstract: Discharge Flow Kinetic Study of the Reactions of NO3 with Br, BrO, HBr, and HCl

ChemInform

Research paper thumbnail of ChemInform Abstract: Discharge Flow Kinetic Study of NO3 Reactions with Free Radicals: The Reaction of NO3 with Cl

ChemInform Abstract: Discharge Flow Kinetic Study of NO3 Reactions with Free Radicals: The Reaction of NO3 with Cl

ChemInform

Research paper thumbnail of Simple and Reversible Transformation of an APCI/MS/MS Into an Aerosol Mass Spectrometer: Development and Characterization of a New Inlet

Aerosol Science and Technology, 2008

The inlet of a commercial atmospheric pressure chemical ionization-mass spectrometer (APCI/MS/MS)... more The inlet of a commercial atmospheric pressure chemical ionization-mass spectrometer (APCI/MS/MS) has been modified to transform it into an aerosol mass spectrometer, named TD-API-AMS. The new inlet consists in a charcoal denuder (to trap gas phase VOCs and SVOCs) followed by the thermal-desorption unit of the APCI source. Thermal desorption and APCI were chosen because they avoid sample denaturizing while keeping good time resolution. The objectives of this paper are (1) to describe the simple and reversible modifications of the commercial APCI inlet allowing its use as an aerosol mass spectrometer and (2) to characterize the performances of this modified inlet. These performances are characterized in term of efficiency of (i) gas phase organic compounds removal, (ii) particle transmission, and (iii) particle volatilization in the thermal-desorption unit. The characterization was conduced with secondary organic aerosol (SOA) produced from the ozonolysis of α-pinene and 2-buten-1-ol in a continuous flow reactor. The results show a denuder gas phase trapping efficiency higher than 93 ± 3% while the particle transmission efficiency was nearly 100% in particle number, but decreased to as little as 85% in total particle volume. This result highlights a shift of the particle distribution towards the fine particles occurring through the denuder, due to a modification of the gas-particle equilibrium. The inlets' characterization has also shown a particle volatilization efficiency higher than 90% (in volume).

Research paper thumbnail of Characteristics and sources of nitrous acid in an urban atmosphere of northern China: Results from 1-yr continuous observations

Atmospheric Environment, 2018

Nitrous acid (HONO) is a key reservoir of the hydroxyl radical (OH) and plays a central role in t... more Nitrous acid (HONO) is a key reservoir of the hydroxyl radical (OH) and plays a central role in the atmospheric chemistry. To understand the sources and impact of HONO in the polluted atmosphere of northern China, continuous measurements of HONO and related parameters were conducted from September 2015 to August 2016 at an urban site in Ji'nan, the capital city of Shandong province. HONO showed well-defined seasonal and diurnal variation patterns with clear wintertime and nighttime concentration peaks. Elevated HONO concentrations (e.g., over 5 ppbv) were frequently observed with a maximum value of 8.36 ppbv. The HONO/NO X ratios of direct vehicle emissions varied in the range of 0.29%-0.87%, with a mean value of 0.53%. An average NO 2-to-HONO nighttime conversion frequency (k het) was derived to be 0.0068±0.0045 h-1 from 107 HONO formation cases. A detailed HONO budget analysis suggests an unexplained daytime missing source of 2.95 ppb h-1 in summer, which is about seven times larger than the homogeneous reaction of NO with OH. The effect of HONO on OH production was also quantified. HONO photolysis was the uppermost source of local OH radical throughout the daytime. This study provides the year-round

Research paper thumbnail of by Laser Photolysis-Laser Induced Fluorescence

by Laser Photolysis-Laser Induced Fluorescence

reactions play a very important role in air pollution. For the majority of chemical compounds of ... more reactions play a very important role in air pollution. For the majority of chemical compounds of theatmosphere, the reaction with OH radicals is an intermediate one, part of a long chain reaction. A Laser Photolysis-LaserInduced Fluorescence (LP-LIF) technique has been used to study OH reaction kinetics with dioxane. The apparatus consistsof two synchronized pulsed laser systems, a six cross flow I

Research paper thumbnail of Trends in atmospheric photodissociation rates of selected carbonyl compounds

Trends in atmospheric photodissociation rates of selected carbonyl compounds

Research paper thumbnail of Photocatalytic abatement results from a model street canyon

Environmental Science and Pollution Research, 2015

Your article is protected by copyright and all rights are held exclusively by Springer-Verlag Ber... more Your article is protected by copyright and all rights are held exclusively by Springer-Verlag Berlin Heidelberg. This e-offprint is for personal use only and shall not be selfarchived in electronic repositories. If you wish to self-archive your article, please use the accepted manuscript version for posting on your own website. You may further deposit the accepted manuscript version in any repository, provided it is only made publicly available 12 months after official publication or later and provided acknowledgement is given to the original source of publication and a link is inserted to the published article on Springer's website. The link must be accompanied by the following text: "The final publication is available at link.springer.com".

Research paper thumbnail of Reaction of Cl Atoms with C 6 F 13 CH 2 OH, C 6 F 13 CHO, and C 3 F 7 CHO

Reaction of Cl Atoms with C 6 F 13 CH 2 OH, C 6 F 13 CHO, and C 3 F 7 CHO

The Journal of Physical Chemistry A, 2006

The Cl atom initiated oxidation of C(6)F(13)CH(2)OH, C(6)F(13)CHO, and C(3)F(7)CHO was investigat... more The Cl atom initiated oxidation of C(6)F(13)CH(2)OH, C(6)F(13)CHO, and C(3)F(7)CHO was investigated at 298 K and 1000 mbar pressure of air in a photoreactor using in situ Fourier transform infrared (FTIR) analysis. The rate coefficient for the reaction Cl + C(6)F(13)CH(2)OH (reaction 2) was measured using a relative method: k(2) = (6.5 +/- 0.8) x 10(-13) cm(3) molecule(-1) s(-1). C(6)F(13)CHO was detected as the major primary product, while CO and CF(2)O were found to be the major secondary products. A fitting procedure applied to the concentration-time profiles of C(6)F(13)CHO provided a production yield of (1.0 +/- 0.2) for this aldehyde in reaction 2, and the rate coefficient for the reaction Cl + C(6)F(13)CHO (reaction 4) was k(4) = (2.8 +/- 0.7) x 10(-12) cm(3) molecule(-1) s(-1). A high CO yield observed in the oxidation of C(6)F(13)CH(2)OH, (52 +/- 1)%, is attributed to the Cl atom initiated oxidation of C(6)F(13)CHO. High CO yields, (61 +/- 2)% and (85 +/- 5)%, were also measured in the Cl atom initiated oxidation of C(3)F(7)CHO in air and nitrogen, respectively. These high CO yields suggest the occurrence of a decomposition reaction of the perfluoroacyl, C(6)F(13)CO, and C(3)F(7)CO radicals to form CO which will compete with the combination reaction of these radicals with oxygen to form perfluoroacyl peroxy radicals in the presence of air. The latter radicals C(n)F(2)(n)(+1)CO(O)(2) (n = 6-12), through their reaction with HO(2) radicals, are currently considered as a possible source of persistent perfluorocarboxylic acids which have been detected in the environment. The consequences of the present results would be a reduction of the strength of this potential source of carboxylic acids in the atmosphere.

Research paper thumbnail of Kinetic Studies on the Reactions of Hydroxyl Radicals with Cyclic Ethers and Aliphatic Diethers

The Journal of Physical Chemistry A, 2006

Bras: Kinetic Studies on the Reactions of Hydroxyl Radicals with Cyclic Ethers and Aliphatic Diet... more Bras: Kinetic Studies on the Reactions of Hydroxyl Radicals with Cyclic Ethers and Aliphatic Diethers Two errors and one omission have been found in the original article. 1 Page 1501: In Table 1, the reference compound used for 1,3dioxepane was in fact (CH 3) 2 CHOCH 2 CH 2 OH and not (CH 3) 2-CH(OH)CH 2 OCH 3. The rate coefficient for reaction of OH with (CH 3) 2 CHOCH 2 CH 2 OH (k 5) was 21.0 × 10-12 cm 3 molecule-1 s-1 , as reported by Porter et al. 2 The reported value of k 4 /k 5 for 1,3-dioxepane, 0.58

Research paper thumbnail of A tunable diode laser absorption spectrometer for formaldehyde atmospheric measurements validated by simulation chamber instrumentation

Journal of Environmental Sciences, 2012

A tunable diode laser absorption spectrometer (TDLAS) for formaldehyde atmospheric measurements h... more A tunable diode laser absorption spectrometer (TDLAS) for formaldehyde atmospheric measurements has been set up and validated through comparison experiments with a Fourier transform infrared spectrometer (FTIR) in a simulation chamber. Formaldehyde was generated in situ in the chamber from reaction of ethene with ozone. Three HCHO rovibrational line intensities (at 2909.71, 2912.09 and 2914.46 cm-1) possibly used by TDLAS were calibrated by FTIR spectra simultaneously recorded in the 1600-3200 cm-1 domain during ethene ozonolysis, enabling the on-line deduction of the varying concentration for HCHO in formation. The experimental line intensities values inferred confirmed the calculated ones from the updated HITRAN database (Rothman et al., 2009, based on Perrin et al., 2009). In addition, the feasibility of stratospheric in situ HCHO measurements using the 2912.09 cm-1 line was demonstrated. The TDLAS performances were also assessed, leading to a 2 detection limit of 88 ppt in volume mixing ratio with a response time of 60 s at 30 Torr and 294 K for 112 m optical path. As part of this work, the room-temperature rate-2-constant of this reaction and the HCHO formation yield were found to be in excellent agreement with the compiled literature data.

Research paper thumbnail of Photolysis of Trichloronitromethane (Chloropicrin) under Atmospheric Conditions

Zeitschrift für Physikalische Chemie, 2010

An experimental investigation on the photolysis of the pesticide chloropicrin, (trichloronitromet... more An experimental investigation on the photolysis of the pesticide chloropicrin, (trichloronitromethane, CCl3NO2), under atmospheric conditions was carried out at the outdoor European Photoreactor, (EUPHORE), in Valencia, Spain. The photodissociation rate coefficient, J obs(CCl3NO2), was determined directly under sunlight conditions during spring and summer months. Values in the range J obs(CCl3NO2) = (3.9–5.1)×10−5 s−1 were obtained, corresponding to photolysis lifetimes of 7.1–5.4 hours. Absorption cross-sections for chloropicrin were determined over the wavelength range 260–370 nm, and together with the measured solar flux intensity, were used to calculate the maximum photolysis rate for chloropicrin, J max. Comparison of the observed photolysis rate with the calculated maximum photolysis rate showed that the effective quantum yield of photodissociation, Φ = J obs(CCl3NO2)/J max, was 0.94±0.08. Photolysis of chloropicrin in air or nitrogen gave phosgene as the major carbon-containi...

Research paper thumbnail of Rate coefficients for the reaction of OH with HONO between 298 and 373 K

International Journal of Chemical Kinetics, 1992

The rate coefficients for the reaction of O H with CHJF, CHF3, CzHsF, C~H~F S , and CSHZFlO were ... more The rate coefficients for the reaction of O H with CHJF, CHF3, CzHsF, C~H~F S , and CSHZFlO were measured at temperatures between 232 and 378 K using the pulsed laser photolysis-laser-induced fluorescence technique. The rate coefficients for the reaction of O(lD) with the above molecules and CHzFz were measured at room temperature using time-resolvedvacuum-UV atomic resonance fluorescence detection of Ot3P). The atmospheric lifetimes needed for the evaluation of global warming potentials were calculated for all six molecules using a one-dimensional atmospheric model using the kinetic data obtained in the present study.

Research paper thumbnail of Kinetics of OH and Cl reactions with a series of aldehydes

Kinetics of OH and Cl reactions with a series of aldehydes

International Journal of Chemical Kinetics, 2000

The rate constants for the reactions of the OH radicals with a series of aldehydes have been meas... more The rate constants for the reactions of the OH radicals with a series of aldehydes have been measured in the temperature range 243–372 K, using the pulsed laser photolysis-pulsed laser induced fluorescence method. The obtained data for propanaldehyde, iso-butyraldehyde, tert-butyraldehyde, and n-pentaldehyde were as follows (in cm3 molecule−1 s−1): (a) in the Arrhenius form: (5.3 ± 0.5) × 10−12 exp[(405 ± 30)/T], (7.3 ± 1.9) × 10−12 exp[(390 ± 78)/T], (4.7 ± 0.8) × 10−12 exp[(564 ± 52)/T], and (9.9 ± 1.9) × 10−12 exp[(306 ± 56)/T]; (b) at 298 K: (2.0 ± 0.3) × 10−11, (2.6 ± 0.4) × 10−11, (2.7 ± 0.4) × 10−11, and (2.8 ± 0.2) × 10−11, respectively. In addition, using the relative rate method and alkanes as the reference compounds, the room-temperature rate constants have been measured for the reactions of chlorine atoms with propanaldehyde, iso-butyraldehyde, tert-butyraldehyde, n-pentaldehyde, acrolein, and crotonaldehyde. The obtained values were (in cm3 molecule−1 s−1): (1.4 ± 0.3) × 10−10, (1.7 ± 0.3)10−10, (1.6 ± 0.3) × 10−10, (2.6 ± 0.3) × 10−10, (2.2 ± 0.3) × 10−10, and (2.6 ± 0.3) × 10−10, respectively. The results are presented and discussed in terms of structure-reactivity relationships and atmospheric importance. © 2000 John Wiley & Sons, Inc. Int J Chem Kinet 32: 676–685, 2000

Research paper thumbnail of Abstracts of the 6th FECS Conference 1998 Lectures

Abstracts of the 6th FECS Conference 1998 Lectures

Environmental Science and Pollution Research, 1998

International audienc

Research paper thumbnail of Evaluated kinetic and photochemical data for atmospheric chemistry: Volume VI – heterogeneous reactions with liquid substrates

Atmospheric Chemistry and Physics, 2013

This article, the sixth in the ACP journal series, presents data evaluated by the IUPAC Task Grou... more This article, the sixth in the ACP journal series, presents data evaluated by the IUPAC Task Group on Atmospheric Chemical Kinetic Data Evaluation. It covers the heterogeneous processes involving liquid particles present in the atmosphere with an emphasis on those relevant for the upper troposphere/lower stratosphere and the marine boundary layer, for which uptake coefficients and adsorption parameters have been presented on the IUPAC website since 2009. The article consists of an introduction and guide to the evaluation, giving a unifying framework for parameterisation of atmospheric heterogeneous processes. We provide summary sheets containing the recommended uptake parameters for the evaluated processes. The experimental data on which the recommendations are based are provided in data sheets in separate appendices for the four surfaces considered: liquid water, deliquesced halide salts, other aqueous electrolytes and sulfuric acid.

Research paper thumbnail of Regional climate variability and its impacts in the Mediterranean area

PREFACE xii are needed. Further, it is clear that long-term monitoring of various calculating emi... more PREFACE xii are needed. Further, it is clear that long-term monitoring of various calculating emissions, atmospheric composition, and transport in and out of the region. Observations of processes that are unique to this region

Research paper thumbnail of Scientific Assessment of Ozone Depletion: 2010

Ajavon, Ayité-Lo Université de Lomé Togo Andersen, Stephen O. Environmental Protection Agency USA... more Ajavon, Ayité-Lo Université de Lomé Togo Andersen, Stephen O. Environmental Protection Agency USA Austin, John NOAA Geophysical Fluid Dynamics Laboratory USA Bais, Alkiviadis F. Aristotle University of Thessaloniki Greece Baldwin, Mark NorthWest Research Associates, Inc. USA Beig, Gufran Indian Institute of Tropical Meteorology India Björn, Lars Olof Lund University Sweden Bodeker, Greg National Institute of Water & Atmospheric Research New Zealand Braathen, Geir World Meteorological Organization Switzerland Burrows, John University of Bremen Germany Chanin, Marie-Lise Service d'Aeronomie du CNRS France Chipperfield, Martyn University of Leeds UK Clerbaux, Catherine Service d'Aeronomie du CNRS France Cunnold, Derek Georgia Institute of Technology USA Dameris, Martin German Aerospace Center (DLR) Institut für Physik der Atmosphäre Germany

Research paper thumbnail of New Measurements of Methyl Ethyl Ketone (MEK) Photolysis Rates and Their Relevance to Global Oxidative Capacity

New Measurements of Methyl Ethyl Ketone (MEK) Photolysis Rates and Their Relevance to Global Oxidative Capacity

Research paper thumbnail of Prise en charge chirurgicale robotique d’un adénome de prostate compliqué d’un volumineux diverticule, technique et complications

Prise en charge chirurgicale robotique d’un adénome de prostate compliqué d’un volumineux diverticule, technique et complications

Progrès en Urologie

Objectif L’adenomectomie voix haute (AVH) assistee par robot represente une alternative chirurgic... more Objectif L’adenomectomie voix haute (AVH) assistee par robot represente une alternative chirurgicale emergeante pour les hypertrophies benignes de prostate (HBP) de haut volume. L’approche transvesicale pourrait permettre de traiter dans le meme temps operatoire d’eventuelles complications diverticulaires associees. Nous en decrivons la technique chirurgicale, les resultats et le risque de complications identifiees par assistance video. Methodes Un patient de 70 ans, sans antecedent chirurgical, presentant une HBP symptomatique de 80 g compliquee d’un diverticule de 350cc, a beneficie d’une AVH robotique avec diverticulectomie synchrone par voie transvesicale. L’intervention etait realisee avec un robot Da-Vinci X® surgical system(intuitive Surgical Inc, Sunnyvale, CA, USA) 4 bras et 2 instruments assistants. Les trocarts places en transperitoneal suivaient une ligne convexe en haut en sus-ombilical, apres open-coelioscopique. Les instruments assistants etaient en pararectal et fosse iliaque gauche. Le robot etait a droite du patient place en Trendelenburg −30°, jambes a l’horizontale, sonde vesicale Ch18 en place. L’intervention etait enregistree pour relecture, les temps operatoires controles. Resultats L’intervention a ete realisee en un seul temps en 4 h, temps de console de 3h40. L’HBP et le diverticule pesaient 62 g et 110 g, respectivement. Les suites operatoires etaient marquees par une complication precoce de douleurs abdominales gauches irradiant dans le dos et une elevation de la creatininemie a 135 μmol/L. Un TDM abdomino-pelvien injecte a J2 revelait une dilatation pyelo-calicielle bilaterale predominant a gauche avec urinome traitee par nephrostomie gauche a J2. Le controle video de l’enregistrement permit d’identifier une section ureterale gauche lors de la dissection a la 17eme minute. Une re-implantation uretero-vesicale gauche par mini-laparotomie a ete realisee. Le controle mictionnel a 3 mois etait satisfaisant, IPSS 4, Qol 1 avec un residu post-mictionnel reduit mais significatif de 244 mL. Conclusion L’adenomectomie avec diverticulectomie par voie transvesicale robotique en un temps est realisable. L’assistance video post-operatoire permet le controle et l’identification des complications. L’enregistrement systematique des interventions pourrait beneficier a la securisation des pratiques.

Research paper thumbnail of Atmospheric degradation of pyridine: UV absorption spectrum and reaction with OH radicals and O 3

Chemical Physics Letters

The UV absorption spectrum of pyridine and its gas phase reactions with OH radicals and O 3 were ... more The UV absorption spectrum of pyridine and its gas phase reactions with OH radicals and O 3 were investigated. UV absorption cross-sections were determined by using a D 2-lamp system in the range 200-350 nm. The kinetic studies were carried out at room temperature and atmospheric pressure of purified air. The rate coefficient for the reaction of pyridine with OH was determined relative to that with acetone while that with O 3 was measured under pseudo first order conditions. The rate coefficients obtained are (in cm 3 molecule-1 s-1): k(OH+Pyridine) = (5.40 ± 0.80) ×10-13 and k(O 3 +Pyridine) = (3.28 ± 1.70) × 10-20 .

Research paper thumbnail of ChemInform Abstract: Discharge Flow Kinetic Study of the Reactions of NO3 with Br, BrO, HBr, and HCl

ChemInform Abstract: Discharge Flow Kinetic Study of the Reactions of NO3 with Br, BrO, HBr, and HCl

ChemInform

Research paper thumbnail of ChemInform Abstract: Discharge Flow Kinetic Study of NO3 Reactions with Free Radicals: The Reaction of NO3 with Cl

ChemInform Abstract: Discharge Flow Kinetic Study of NO3 Reactions with Free Radicals: The Reaction of NO3 with Cl

ChemInform