Back to basics, the chemistry of aerosol formation, viewed with velocity-map imaging of photoelectrons

2014 ◽  
Author(s):  
Stephen T. Gibson ◽  
Steven J. Cavanagh ◽  
Brenton R. Lewis ◽  
Franklin P. Mills
Keyword(s):  
Velocity Map Imaging ◽  
Aerosol Formation

Effects of continental boundary layer evolution, convection, turbulence and entrainment, on aerosol formation

Tellus B ◽  
2001 ◽  
Vol 53 (4) ◽  
pp. 441-461 ◽  
Author(s):  
E. D. NILSSON ◽  
Ü. RANNIK ◽  
M. KULMALA ◽  
G. BUZORIUS ◽  
C. D. O'DOWD
Keyword(s):  
Boundary Layer ◽  
Aerosol Formation

Overview of the international project on biogenic aerosol formation in the boreal forest (BIOFOR)

Tellus B ◽  
2001 ◽  
Vol 53 (4) ◽  
pp. 324-343 ◽  
Author(s):  
M. KULMALA ◽  
K. HÄMERI ◽  
P. P. AALTO ◽  
J. M. MÄKELÄ ◽  
L. PIRJOLA ◽  
...  
Keyword(s):  
Boreal Forest ◽  
International Project ◽  
Aerosol Formation

Isomerization of the Isoprene Hydroxy Nitrates and Formation of Orthonitrite Compounds

2019 ◽  
Author(s):  
Gabriel da Silva
Keyword(s):  
Hydroxy Group ◽  
Peroxyl Radical ◽  
Branching Fractions ◽  
Membered Ring ◽  
Low Energy ◽  
Peroxyl Radicals ◽  
Aerosol Formation ◽  
Subsequent Removal ◽  
Ring Compounds ◽  
Group Migration

Atmospheric oxidation of isoprene produces significant yields of eight unique nitrate 11 compounds, each with a β- or δ-hydroxy group. These isoprene hydroxy nitrates (ISOPNs) 12 significantly impact upon global NOx budgets, O3 levels, and aerosol formation. 13 Uncertainties exist, however, in our understanding of ISOPN chemistry, particularly in their 14 yields from the reaction of isoprene peroxyl radicals with NO. This study describes novel 15 isomerization reactions of the ISOPNs, identified through the application of computational 16 chemistry techniques. These reactions produce saturated polycyclic orthonitrite compounds 17 via attack of the R–NO2 group on the vinyl moiety. For the δ-hydroxy nitrates, low-energy 18 isomerization pathways exist to six-membered ring compounds that are around 5 kcal mol-1 19 exothermic. These reactions proceed with barriers around 15 kcal mol-1 below the 20 respective peroxyl radical + NO reactants and yield orthonitrites that can further isomerize 21 to β-hydroxy ISOPNs. Moreover, the δ-hydroxy nitrates can directly interconvert with their β 22 substituted counterparts via NO3 group migration, with barriers that are lower yet. It follows 23 that β-hydroxy nitrates may be stabilized in the δ-hydroxy form, and vice versa. Moreover, 24 the lowest-energy pathway for dissociation of the δ-hydroxy ISOPNs is for the formation of 25 β-hydroxy alkoxyl radicals, and because of this established branching fractions between the 26 various isoprene peroxyl radicals may require re-evaluation. The results presented here also 27 suggest that ISOPNs may be stabilized to some extent in their saturated orthonitrite forms, 28 which has implications for both the total nitrate yield and for their subsequent removal by 29 OH, O3, and photolysis.<br><br>

Awareness and perception of precautionary measures against Covid 19 exposure among dental practitioners- A questionnaire based study

2020 ◽  
Vol 11 (SPL1) ◽  
pp. 550-557
Author(s):  
Harini P ◽  
Abilasha R
Keyword(s):  
Statistical Analysis ◽  
Aerosol Formation ◽  
Dental Clinic ◽  
Attitude And Practice ◽  
Dental Practitioners ◽  
Hands On ◽  
The World ◽  
Spss Software ◽  
Precautionary Measures ◽  
Knowledge And Attitude

The most unexpected pandemic global outbreak is COVID 19 which is a newly discovered viral infection which originated in Wuhan, China and it caused the outbreak of pneumonia in the rest of the world. Dental practitioners are more susceptible to COVID 19 infection as their work is related to the aerosol formation during various procedures through which the virus spreads. The aim of the study is to create awareness about precautionary measures against COVID- 19 exposure among dental practitioners in Tamilnadu. A Survey based questionnaire was formulated with questions related to the various precautionary measures to be adopted by dental practitioners which would be effective to prevent Covid-19 exposure. A questionnaire with a total of 20 questions was circulated among dental practitioners and the responses were collected by google forms SPSS software statistical analysis was done. The overall awareness of dental practitioners against Covid-19 was above average. The dental practitioners were relatively well aware of the precautions to be adopted while treating the patients, but the implementation in practice is lacking due absence of hands-on experience in using various kinds of PPE. There is a gap between knowledge and attitude and practice among the participants of this survey. It is therefore essential to plan for organising training sessions and hands-on workshops for the use of PPE and public training of the general population regarding Covid-19 to improve the knowledge among the patients visiting the dental clinic as well.

scholarly journals Secondary organic aerosol formation from biomass burning emissions

2019 ◽  
Author(s):  
Christopher Y. Lim ◽  
David H. Hagan ◽  
Matthew M. Coggon ◽  
Abigail R. Koss ◽  
Kanako Sekimoto ◽  
...  
Keyword(s):  
Biomass Burning ◽  
Secondary Organic Aerosol ◽  
Total Concentration ◽  
Organic Aerosol ◽  
Oh Radicals ◽  
Aerosol Formation ◽  
Atmospheric Aging ◽  
Aerosol Mass ◽  
Photochemical Aging ◽  
Organic Gases

Abstract. Biomass burning is an important source of aerosol and trace gases to the atmosphere, but how these emissions change chemically during their lifetimes is not fully understood. As part of the Fire Influence on Regional and Global Environments Experiment (FIREX 2016), we investigated the effect of photochemical aging on biomass burning organic aerosol (BBOA), with a focus on fuels from the western United States. Emissions were sampled into a small (150 L) environmental chamber and photochemically aged via the addition of ozone and irradiation by 254 nm light. While some fraction of species undergoes photolysis, the vast majority of aging occurs via reaction with OH radicals, with total OH exposures corresponding to the equivalent of up to 10 days of atmospheric oxidation. For all fuels burned, large and rapid changes are seen in the ensemble chemical composition of BBOA, as measured by an aerosol mass spectrometer (AMS). Secondary organic aerosol (SOA) formation is seen for all aging experiments and continues to grow with increasing OH exposure, but the magnitude of the SOA formation is highly variable between experiments. This variability can be explained well by a combination of experiment-to-experiment differences in OH exposure and the total concentration of non-methane organic gases (NMOGs) in the chamber before oxidation, measured by PTR-ToF-MS (r2 values from 0.64 to 0.83). From this relationship, we calculate the fraction of carbon from biomass burning NMOGs that is converted to SOA as a function of equivalent atmospheric aging time, with carbon yields ranging from 24 ± 4 % after 6 hours to 56 ± 9 % after 4 days.

scholarly journals A compact electrostatic lens for velocity map imaging experiments

2021 ◽  
pp. e1910357
Author(s):  
E. Sakkoula ◽  
B. G. M. van Oorschot ◽  
D. H. Parker
Keyword(s):  
Velocity Map Imaging ◽  
Electrostatic Lens
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