Gas-Phase Chlorine Radical Oxidation of Alkanes: Effects of Structural Branching, NOx, and Relative Humidity Observed during Environmental Chamber Experiments

2021 ◽  
Author(s):  
Leif G. Jahn ◽  
Dongyu S. Wang ◽  
Surya Venkatesh Dhulipala ◽  
Lea Hildebrandt Ruiz
Keyword(s):  
Relative Humidity ◽  
Gas Phase ◽  
Environmental Chamber ◽  
Radical Oxidation

scholarly journals Evaluation of the chemical composition of gas- and particle-phase products of aromatic oxidation

2020 ◽  
Vol 20 (16) ◽  
pp. 9783-9803
Author(s):  
Archit Mehra ◽  
Yuwei Wang ◽  
Jordan E. Krechmer ◽  
Andrew Lambe ◽  
Francesca Majluf ◽  
...  
Keyword(s):  
Gas Phase ◽  
Mass Spectrometer ◽  
Urban Areas ◽  
Minor Component ◽  
Proton Transfer Reaction ◽  
Chemical Mechanism ◽  
Particle Phase ◽  
Experimental Conditions ◽  
Radical Oxidation ◽  
Product Ions

Abstract. Aromatic volatile organic compounds (VOCs) are key anthropogenic pollutants emitted to the atmosphere and are important for both ozone and secondary organic aerosol (SOA) formation in urban areas. Recent studies have indicated that aromatic hydrocarbons may follow previously unknown oxidation chemistry pathways, including autoxidation that can lead to the formation of highly oxidised products. In this study we evaluate the gas- and particle-phase ions measured by online mass spectrometry during the hydroxyl radical oxidation of substituted C9-aromatic isomers (1,3,5-trimethylbenzene, 1,2,4-trimethylbenzene, propylbenzene and isopropylbenzene) and a substituted polyaromatic hydrocarbon (1-methylnaphthalene) under low- and medium-NOx conditions. A time-of-flight chemical ionisation mass spectrometer (ToF-CIMS) with iodide–anion ionisation was used with a filter inlet for gases and aerosols (FIGAERO) for the detection of products in the particle phase, while a Vocus proton-transfer-reaction mass spectrometer (Vocus-PTR-MS) was used for the detection of products in the gas phase. The signal of product ions observed in the mass spectra were compared for the different precursors and experimental conditions. The majority of mass spectral product signal in both the gas and particle phases comes from ions which are common to all precursors, though signal distributions are distinct for different VOCs. Gas- and particle-phase composition are distinct from one another. Ions corresponding to products contained in the near-explicit gas phase Master Chemical Mechanism (MCM version 3.3.1) are utilised as a benchmark of current scientific understanding, and a comparison of these with observations shows that the MCM is missing a range of highly oxidised products from its mechanism. In the particle phase, the bulk of the product signal from all precursors comes from ring scission ions, a large proportion of which are more oxidised than previously reported and have undergone further oxidation to form highly oxygenated organic molecules (HOMs). Under the perturbation of OH oxidation with increased NOx, the contribution of HOM-ion signals to the particle-phase signal remains elevated for more substituted aromatic precursors. Up to 43 % of product signal comes from ring-retaining ions including HOMs; this is most important for the more substituted aromatics. Unique products are a minor component in these systems, and many of the dominant ions have ion formulae concurrent with other systems, highlighting the challenges in utilising marker ions for SOA.

scholarly journals Biology of Anicla infecta (Ochsenheimer, 1816) (Lepidoptera, Noctuidae, Noctuinae), under laboratory conditions

2001 ◽  
Vol 61 (4) ◽  
pp. 661-666 ◽  
Author(s):  
J. A. TESTON ◽  
A. SPECHT ◽  
E. CORSEUIL
Keyword(s):  
Relative Humidity ◽  
Standard Error ◽  
Lolium Multiflorum ◽  
Economic Importance ◽  
Egg Laying ◽  
Adult Longevity ◽  
Environmental Chamber ◽  
Laboratory Conditions ◽  
The Mean ◽  
Lepidoptera Noctuidae

Larvae of Anicla infecta (Ochsenheimer, 1816) (Noctuidae) feed upon many grasses and may be harmful to cereals and fodder of economic importance. This study was developed aiming to contribute to knowledge of the biology of this species. The rearing was done in an environmental chamber with the following settings: temperature of 25 ± 1ºC; relative humidity of 70% <FONT FACE=Symbol>±</FONT> 10%, and photoperiod of L14: D10. The larvae fed on ryegrass, Lolium multiflorum Lam. The results express the mean and standard error for the length of every stage in days. For each stage we observed the following time of development: egg 3.2 <FONT FACE=Symbol>±</FONT> 0.09; larvae 18.7 <FONT FACE=Symbol>±</FONT> 0.07; pre-pupae 3.3 <FONT FACE=Symbol>±</FONT> 0.04; pupae 12.6 <FONT FACE=Symbol>±</FONT> 0.14; and adult longevity was 12.1 <FONT FACE=Symbol>±</FONT> 1.03. Also the pre-egg-laying period was 4.4 <FONT FACE=Symbol>±</FONT> 0.59; the egg-laying period was 8.1 <FONT FACE=Symbol>±</FONT> 0.84; and the post-egg-laying period was 0.3 <FONT FACE=Symbol>±</FONT> 0.14. The mean number of egg-laying cycles per female was 6.7 <FONT FACE=Symbol>±</FONT> 0.73; that of eggs per cycle was 77.5 <FONT FACE=Symbol>±</FONT> 4.37; and total eggs per female was 521.4 <FONT FACE=Symbol>±</FONT> 47.36.

scholarly journals Environmental chamber with controlled temperature and relative humidity for ice crystallization kinetic measurements by atomic force microscopy

2020 ◽  
Vol 91 (2) ◽  
pp. 023704 ◽  
Author(s):  
Melisa M. Gianetti ◽  
Julián Gelman Constantin ◽  
Horacio R. Corti ◽  
M. Paula Longinotti
Keyword(s):  
Atomic Force Microscopy ◽  
Relative Humidity ◽  
Crystallization Kinetic ◽  
Kinetic Measurements ◽  
Environmental Chamber ◽  
Force Microscopy ◽  
Atomic Force ◽  
Ice Crystallization

The Mechanism of Methoxy Radical Oxidation by O2in the Gas Phase. Computational Evidence for Direct H Atom Transfer Assisted by an Intermolecular Noncovalent O···O Bonding Interaction

1999 ◽  
Vol 121 (6) ◽  
pp. 1337-1347 ◽  
Author(s):  
Josep M. Bofill ◽  
Santiago Olivella ◽  
Albert Solé ◽  
Josep M. Anglada
Keyword(s):  
Gas Phase ◽  
Atom Transfer ◽  
Radical Oxidation ◽  
Bonding Interaction ◽  
Methoxy Radical

Gas-phase filters breakthrough models at low concentration – Effect of relative humidity

2014 ◽  
Vol 75 ◽  
pp. 1-10 ◽  
Author(s):  
Ali Khazraei Vizhemehr ◽  
Fariborz Haghighat ◽  
Chang-Seo Lee
Keyword(s):  
Relative Humidity ◽  
Gas Phase ◽  
Concentration Effect ◽  
Low Concentration

scholarly journals HumidOSH: A self-contained environmental chamber with controls for relative humidity and fan speed

HardwareX ◽  
2020 ◽  
Vol 8 ◽  
pp. e00141 ◽  
Author(s):  
Soon Kiat Lau ◽  
Jeyamkondan Subbiah
Keyword(s):  
Relative Humidity ◽  
Environmental Chamber ◽  
Fan Speed

scholarly journals Exploring the chemical fate of the sulfate radical anion by reaction with sulfur dioxide in the gas phase

2014 ◽  
Vol 14 (9) ◽  
pp. 12863-12886
Author(s):  
N. T. Tsona ◽  
N. Bork ◽  
H. Vehkamäki
Keyword(s):  
Relative Humidity ◽  
Gas Phase ◽  
Reaction Rate ◽  
Reaction Rate Constant ◽  
Phase Reaction ◽  
So2 Oxidation ◽  
Gas Phase Reaction ◽  
Cluster Ion ◽  
Anionic Cluster ◽  
Sulfate Radical Anion

Abstract. The gas phase reaction between SO4−(H2O)n and SO2, n = 0–2, is investigated using ab initio calculations and kinetic modeling. Structures of reactants, transition states and products are reported. Our calculations predict that the SO2SO4−(H2O)n cluster ion, formed upon SO2 and SO4−(H2O)n collision, can isomerize to SO3SO3−(H2O)n. The overall reaction is SO2 oxidation by the SO4−(H2O)n anionic cluster. The results show that SO4−(H2O)n is a good SO2 oxidant, especially at low relative humidity, with a~reaction rate constant up to 1.1 × 10−10 cm3 molecule−1 s−1. At high relative humidity, instead, the re-evaporation of SO2 from the SO2SO4−(H2O)n cluster ion is favoured.

83. Effect of High Relative Humidity on Performance of PDR-100 Nephelometric Aerosol Monitor for Sampling Ambient Particulate Within a Controlled Environmental Chamber

2002 ◽  
Author(s):  
B. Samimi ◽  
A. Jalocon ◽  
J. Quintana ◽  
C. Bufalino ◽  
R. Delfino
Keyword(s):  
Relative Humidity ◽  
High Relative Humidity ◽  
Environmental Chamber

scholarly journals Secondary organic aerosol formation in cloud droplets and aqueous particles (aqSOA): a review of laboratory, field and model studies

2011 ◽  
Vol 11 (21) ◽  
pp. 11069-11102 ◽  
Author(s):  
B. Ervens ◽  
B. J. Turpin ◽  
R. J. Weber
Keyword(s):  
Relative Humidity ◽  
Gas Phase ◽  
Atmospheric Chemistry ◽  
Secondary Organic Aerosol ◽  
Current Knowledge ◽  
Laboratory Data ◽  
Organic Aerosol ◽  
Current Data ◽  
Aerosol Formation ◽  
Model Studies

Abstract. Progress has been made over the past decade in predicting secondary organic aerosol (SOA) mass in the atmosphere using vapor pressure-driven partitioning, which implies that SOA compounds are formed in the gas phase and then partition to an organic phase (gasSOA). However, discrepancies in predicting organic aerosol oxidation state, size and product (molecular mass) distribution, relative humidity (RH) dependence, color, and vertical profile suggest that additional SOA sources and aging processes may be important. The formation of SOA in cloud and aerosol water (aqSOA) is not considered in these models even though water is an abundant medium for atmospheric chemistry and such chemistry can form dicarboxylic acids and "humic-like substances" (oligomers, high-molecular-weight compounds), i.e. compounds that do not have any gas phase sources but comprise a significant fraction of the total SOA mass. There is direct evidence from field observations and laboratory studies that organic aerosol is formed in cloud and aerosol water, contributing substantial mass to the droplet mode. This review summarizes the current knowledge on aqueous phase organic reactions and combines evidence that points to a significant role of aqSOA formation in the atmosphere. Model studies are discussed that explore the importance of aqSOA formation and suggestions for model improvements are made based on the comprehensive set of laboratory data presented here. A first comparison is made between aqSOA and gasSOA yields and mass predictions for selected conditions. These simulations suggest that aqSOA might contribute almost as much mass as gasSOA to the SOA budget, with highest contributions from biogenic emissions of volatile organic compounds (VOC) in the presence of anthropogenic pollutants (i.e. NOx) at high relative humidity and cloudiness. Gaps in the current understanding of aqSOA processes are discussed and further studies (laboratory, field, model) are outlined to complement current data sets.

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