scholarly journals Highly oxygenated organic molecule (HOM) formation in the isoprene oxidation by NO<sub>3</sub> radical

2021 ◽  
Vol 21 (12) ◽  
pp. 9681-9704
Author(s):  
Defeng Zhao ◽  
Iida Pullinen ◽  
Hendrik Fuchs ◽  
Stephanie Schrade ◽  
Rongrong Wu ◽  
...  
Keyword(s):  
Double Bond ◽  
First Generation ◽  
Second Generation ◽  
Closed Shell ◽  
Time Profile ◽  
Direct Reaction ◽  
Peroxy Radicals ◽  
Experimental Conditions ◽  
Time Profiles ◽  
Carbon Double Bond

Abstract. Highly oxygenated organic molecules (HOM) are found to play an important role in the formation and growth of secondary organic aerosol (SOA). SOA is an important type of aerosol with significant impact on air quality and climate. Compared with the oxidation of volatile organic compounds by ozone (O3) and hydroxyl radical (OH), HOM formation in the oxidation by nitrate radical (NO3), an important oxidant at nighttime and dawn, has received less attention. In this study, HOM formation in the reaction of isoprene with NO3 was investigated in the SAPHIR chamber (Simulation of Atmospheric PHotochemistry In a large Reaction chamber). A large number of HOM, including monomers (C5), dimers (C10), and trimers (C15), both closed-shell compounds and open-shell peroxy radicals (RO2), were identified and were classified into various series according to their formula. Their formation pathways were proposed based on the peroxy radicals observed and known mechanisms in the literature, which were further constrained by the time profiles of HOM after sequential isoprene addition to differentiate first- and second-generation products. HOM monomers containing one to three N atoms (1–3N-monomers) were formed, starting with NO3 addition to carbon double bond, forming peroxy radicals, followed by autoxidation. 1N-monomers were formed by both the direct reaction of NO3 with isoprene and of NO3 with first-generation products. 2N-monomers (e.g., C5H8N2On(n=7–13), C5H10N2On(n=8–14)) were likely the termination products of C5H9N2On⚫, which was formed by the addition of NO3 to C5-hydroxynitrate (C5H9NO4), a first-generation product containing one carbon double bond. 2N-monomers, which were second-generation products, dominated in monomers and accounted for ∼34 % of all HOM, indicating the important role of second-generation oxidation in HOM formation in the isoprene + NO3 reaction under our experimental conditions. H shift of alkoxy radicals to form peroxy radicals and subsequent autoxidation (“alkoxy–peroxy” pathway) was found to be an important pathway of HOM formation. HOM dimers were mostly formed by the accretion reaction of various HOM monomer RO2 and via the termination reactions of dimer RO2 formed by further reaction of closed-shell dimers with NO3 and possibly by the reaction of C5–RO2 with isoprene. HOM trimers were likely formed by the accretion reaction of dimer RO2 with monomer RO2. The concentrations of different HOM showed distinct time profiles during the reaction, which was linked to their formation pathway. HOM concentrations either showed a typical time profile of first-generation products, second-generation products, or a combination of both, indicating multiple formation pathways and/or multiple isomers. Total HOM molar yield was estimated to be 1.2 %-0.7%+1.3%, which corresponded to a SOA yield of ∼3.6 % assuming the molecular weight of C5H9NO6 as the lower limit. This yield suggests that HOM may contribute a significant fraction to SOA yield in the reaction of isoprene with NO3.

scholarly journals Highly oxygenated organic molecules (HOM) formation in the isoprene oxidation by NO<sub>3</sub> radical

2020 ◽  
Author(s):  
Defeng Zhao ◽  
Iida Pullinen ◽  
Hendrik Fuchs ◽  
Stephanie Schrade ◽  
Rongrong Wu ◽  
...  
Keyword(s):  
Double Bond ◽  
First Generation ◽  
Second Generation ◽  
Organic Molecules ◽  
Closed Shell ◽  
Direct Reaction ◽  
Peroxy Radicals ◽  
Night Time ◽  
Time Profiles ◽  
Carbon Double Bond

Abstract. Highly oxygenated organic molecules (HOM) are found to play an important role in the formation and growth of secondary organic aerosol (SOA). SOA is an important type of aerosol with significant impact on air quality and climate. Compared with the oxidation of volatile organic compounds by O3 and OH, HOM formation in the oxidation by NO3 radical, an important oxidant at night-time and dawn, has received less attention. In this study, HOM formation in the reaction of isoprene with NO3 was investigated in the SAPHIR chamber (Simulation of Atmospheric PHotochemistry In a large Reaction chamber). A large number of HOM including monomers (C5), dimers (C10), and trimers (C15), both closed-shell compounds and open-shell peroxy radicals, were identified and were classified into various series according to their formula. Their formation pathways were proposed based on the peroxy radicals observed and known mechanisms in the literature, which were further constrained by the time profiles of HOM after sequential isoprene addition to differentiate first- and second-generation products. HOM monomers containing one to three N atoms (1–3N monomers) were formed, starting with NO3 addition to carbon double bond, forming peroxy radicals (RO2), followed by autoxidation. 1N monomers were formed by both the direct reaction of NO3 with isoprene and of NO3 with first-generation products. 2N-monomers (e.g. C5H8N2On (n = 8–13), C5H10N2On (n = 8–14)) were likely the termination products of C5H9N2On•, which was formed by the addition of NO3 to C5-hydroxynitrate (C5H9NO4), a first-generation product containing one carbon double bond. 2N-monomers, which were second-generation products, dominated in monomers and accounted for ~34 % of all HOM, indicating the important role of second-generation oxidation in HOM formation in isoprene+NO3 under our reaction conditions. H-shift of alkoxy radicals to form peroxy radicals and subsequent autoxidation (alkoxy-peroxy pathway) was found to be an important pathway of HOM formation. HOM dimers were mostly formed by the accretion reaction of various HOM monomer RO2 and via the termination reactions of dimer RO2 formed by further reaction of closed-shell dimers with NO3 and possibly by the reaction of C5-RO2 with isoprene. HOM trimers were likely formed by the accretion reaction of dimer RO2 with monomer RO2. The concentrations of different HOM showed distinct time profiles during the reaction, which was linked to their formation pathway. HOM concentrations either showed a typical time profile of first-generation products, or of second-generation products, or a combination of both, indicating multiple formation pathways and/or multiple isomers. Total HOM molar yield was estimated to be 1.2 %+1.3 %−0.7 %, which corresponded to a SOA yield of ~3.6 % assuming the molecular weight of C5H9NO6 as the lower limit. This yield suggests that HOM may contribute a significant fraction to SOA yield in the reaction of isoprene with NO3.

scholarly journals Biomass burning plume chemistry: OH radical initiated oxidation of 3-penten-2-one and its main oxidation product 2-hydroxypropanal

2021 ◽  
Author(s):  
Niklas Illmann ◽  
Iulia Patroescu-Klotz ◽  
Peter Wiesen
Keyword(s):  
Biomass Burning ◽  
First Generation ◽  
Rate Coefficient ◽  
Reaction System ◽  
Oh Radical ◽  
Peroxy Radicals ◽  
Methyl Glyoxal ◽  
Experimental Conditions ◽  
Temporal Behaviour ◽  
Radical Yield

Abstract. In order to enlarge our understanding of biomass burning plume chemistry, the OH radical initiated oxidation of 3-penten-2-one (3P2), identified in biomass burning emissions, and 2-hydroxypropanal (2HPr) were investigated at 298 ± 3 K and 990 ± 15 mbar in two atmospheric simulation chambers using long-path FTIR spectroscopy. The rate coefficient of 3P2 + OH was determined to be (6.2 ± 1.0) × 10−11 cm3 molecule−1 s−1 and the molar first-generation yields for acetaldehyde, methyl glyoxal, 2HPr and the sum of PAN and CO2, used to determine the CH3C(O) radical yield, were 0.39 ± 0.07, 0.32 ± 0.08, 0.68 ± 0.27, and 0.56 ± 0.14, respectively, under conditions where the 3P2 derived peroxy radicals react solely with NO. The 2HPr + OH reaction was investigated using 3P2 + OH as a source of the α-hydroxyaldehyde adjusting the experimental conditions to shift the reaction system towards secondary oxidation processes. The rate coefficient was estimated to be (2.2 ± 0.6) × 10−11 cm3 molecule−1 s−1. Employing an Euler-Cauchy model to describe the temporal behaviour of the experiments, the further oxidation of 2HPr was shown to form methyl glyoxal, acetaldehyde and CO2 with estimated yields of 0.21 ± 0.05, 0.79 ± 0.05, and 0.79 ± 0.05, respectively.

Double Bonds are Key to Fast Unimolecular Reactivity in First Generation Monoterpene Hydroxy Peroxy Radicals

2020 ◽  
Author(s):  
Jing Chen ◽  
Kristian H. Møller ◽  
Rasmus V. Otkjær ◽  
Henrik G. Kjaergaard
Keyword(s):  
Double Bond ◽  
Reaction Rate ◽  
First Generation ◽  
Rate Coefficients ◽  
Unimolecular Reaction ◽  
Peroxy Radicals ◽  
Double Bonds ◽  
Bimolecular Reactions ◽  
Unimolecular Reactions ◽  
Volatile Organic

&lt;p&gt;Monoterpenes are a group of volatile organic compounds that are emitted to the atmosphere in large amounts by natural sources. Some monoterpenes such as limonene and &amp;#916;&lt;sup&gt;3&lt;/sup&gt;-carene are also widely used as additives in detergents and perfumes, and thus have a potential impact on indoor air quality and human health.&lt;/p&gt;&lt;p&gt;The volatile organic compounds like monoterpenes may undergo a series of autoxidation processes in the atmosphere to form highly oxygenated compounds, which have been linked to the formation of secondary organic aerosols. For this process to occur, the unimolecular reactions of the peroxy radicals formed during oxidation must have rate coefficients comparable to or greater than those of the competing bimolecular reactions with HO&lt;sub&gt;2&lt;/sub&gt;, NO or other RO&lt;sub&gt;2&lt;/sub&gt; radicals.&lt;/p&gt;&lt;p&gt;We studied the hydrogen shift (H-shift) and the cyclization reactions of all 45 hydroxy peroxy radicals formed by hydroxyl radical (OH) and O&lt;sub&gt;2&lt;/sub&gt; addition to six monoterpenes (&amp;#945;-pinene, &amp;#946;-pinene, &amp;#916;&lt;sup&gt;3&lt;/sup&gt;-carene, camphene, limonene and terpinolene). The reaction rate coefficients of the possible unimolecular reaction were initially studied at a lower level of theory. Those deemed likely to be atmospherically competitive were then calculated using the multi-conformer transition states theory approach developed by M&amp;#248;ller et al. (J. Phys. Chem. A, 120, 51, 10072-10087, 2016). This approach has been shown to agree with the experimental values to within a factor of 4 for other systems.&lt;/p&gt;&lt;p&gt;It was found that double bonds are key to fast unimolecular reactions in the first-generation monoterpene hydroxy peroxy radicals. The H-shift reactions abstracting a hydrogen from a carbon adjacent to a double bond are found to typically be fast enough to compete with the bimolecular reactions, likely due to the resonance stability of the nascent allylic radical. The reactivity of the cyclization reaction between the carbon-carbon double bonds and the peroxy group, which forms an endoperoxide ring, is high as well. The H-shifts abstracting the hydrogen from the hydroxy group may be competitive in some cases but the reaction rate coefficients for these reactions are more uncertain. Generally, the cyclization reaction and the allylic H-shift reactions are the dominant reaction paths for the studied peroxyl radicals. Since the OH radical addition consumes one double bond, we suggest that the monoterpenes with more than one double bond in their structure are likely to have unimolecular reactions that can be important for the first-generation monoterpene peroxy radicals. On the other hand, the ones with only one double bond initially are not likely to have fast unimolecular reactions that can compete with the bimolecular reactions under the atmospheric condition, unless a double bond can be formed during their oxidation process as found for &amp;#945;-pinene and &amp;#946;-pinene. This result greatly limits the amount of potentially important unimolecular reaction paths in atmospheric monoterpene oxidation.&lt;/p&gt;

scholarly journals Biomass burning plume chemistry: OH-radical-initiated oxidation of 3-penten-2-one and its main oxidation product 2-hydroxypropanal

2021 ◽  
Vol 21 (24) ◽  
pp. 18557-18572
Author(s):  
Niklas Illmann ◽  
Iulia Patroescu-Klotz ◽  
Peter Wiesen
Keyword(s):  
Biomass Burning ◽  
First Generation ◽  
Rate Coefficient ◽  
Reaction System ◽  
Chemical Mechanism ◽  
Oh Radical ◽  
Peroxy Radicals ◽  
Methyl Glyoxal ◽  
Experimental Conditions ◽  
Temporal Behaviour

Abstract. In order to enlarge our understanding of biomass burning plume chemistry, the OH-radical-initiated oxidation of 3-penten-2-one (3P2), identified in biomass burning emissions, and 2-hydroxypropanal (2HPr) was investigated at 298 ± 3 K and 990 ± 15 mbar in two atmospheric simulation chambers using long-path FTIR spectroscopy. The rate coefficient of 3P2 + OH was determined to be (6.2 ± 1.0) × 10−11 cm3 molec.−1 s−1 and the molar first-generation yields for acetaldehyde, methyl glyoxal, 2HPr, and the sum of peroxyacetyl nitrate (PAN) and CO2, used to determine the CH3C(O) radical yield, were 0.39 ± 0.07, 0.32 ± 0.08, 0.68 ± 0.27, and 0.56 ± 0.14, respectively, under conditions where the 3P2-derived peroxy radicals react solely with NO. The 2HPr + OH reaction was investigated using 3P2 + OH as a source of the α-hydroxyaldehyde adjusting the experimental conditions to shift the reaction system towards secondary oxidation processes. The rate coefficient was estimated to be (2.2 ± 0.6) × 10−11 cm3 molec.−1 s−1. Employing a simple chemical mechanism to analyse the temporal behaviour of the experiments, the further oxidation of 2HPr was shown to form methyl glyoxal, acetaldehyde, and CO2 with estimated yields of 0.27 ± 0.08, 0.73 ± 0.08, and 0.73 ± 0.08, respectively.

Highly oxygenated organic molecules (HOM) formation in the isoprene oxidation by NO3 radical

2021 ◽  
Author(s):  
Defeng Zhao ◽  
Iida Pullinen ◽  
Hendrik Fuchs ◽  
Stephanie Schrade ◽  
Rongrong Wu ◽  
...  
Keyword(s):  
Organic Molecules ◽  
Closed Shell ◽  
Open Shell ◽  
Reaction Chamber ◽  
Peroxy Radicals ◽  
Night Time ◽  
Time Profiles ◽  
No3 Radical ◽  
Isoprene Oxidation ◽  
First And Second Generation

&lt;p&gt;&lt;strong&gt;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160; &lt;/strong&gt;Highly oxygenated organic molecules (HOM) are found to play an important role in the formation and growth of secondary organic aerosol (SOA). SOA is an important type of aerosol with significant impact on air quality and climate. Compared to the oxidation of volatile organic compounds by O&lt;sub&gt;3&lt;/sub&gt; and OH, HOM formation in the oxidation by NO&lt;sub&gt;3&lt;/sub&gt; radical, an important oxidant at night-time and dawn, has received less attention. In this study, HOM formation in the reaction of isoprene with NO&lt;sub&gt;3&lt;/sub&gt; was investigated in the SAPHIR chamber (Simulation of Atmospheric PHotochemistry In a large Reaction chamber). A large number of HOM including monomers (C&lt;sub&gt;5&lt;/sub&gt;), dimers (C&lt;sub&gt;10&lt;/sub&gt;), and trimers (C&lt;sub&gt;15&lt;/sub&gt;), both closed-shell compounds and open-shell peroxy radicals, were detected. HOM were classified into various series according to their formula, which included monomers containing one or more N atoms, dimers containing 1-4 N atoms, and trimers containing 3-5 N atoms. Tentative formation pathways of HOM were proposed reflecting known NO&lt;sub&gt;3&lt;/sub&gt; and RO&lt;sub&gt;2&lt;/sub&gt; chemistry in the literature under consideration of the autoxidation via peroxy pathways and peroxy-alkoxy pathways. Further mechanistic constraints were given by the time profiles of HOM after sequential isoprene addition which enabled to differentiate first- and second-generation products. Total HOM molar yield was estimated, which suggests that HOM may contribute a significant fraction to SOA yield in the reaction of isoprene with NO&lt;sub&gt;3&lt;/sub&gt;.&lt;/p&gt;

Do remittances differ depending on migration pathway and length of stay?

2016 ◽  
Vol 1 (1) ◽  
pp. 105-118
Author(s):  
Anita Pugliese ◽  
Julie Ray ◽  
Neli Esipova
Keyword(s):  
Length Of Stay ◽  
First Generation ◽  
Second Generation ◽  
Global Analysis ◽  
Large Sample ◽  
Migration Pathway ◽  
First Generation Migrants ◽  
Second Generation Migrants

This paper reports the results from Gallup’s global analysis of the likelihood of first-generation migrants, second-generation migrants and the native-born to send financial help in the form of money or goods to others inside or outside their respective country of residence. The findings in this paper are based on more than 450,000 interviews conducted through Gallup’s World Poll in 157 countries in 2012, 2013 and 2014. The sample includes more than 26,000 first-generation migrants and more than 20,000 second-generation migrants. The large sample enables Gallup to analyze first-generation migrants by the duration of their stay in their adopted country and compare their remittance behaviors with second-generation migrants and the native-born.

Marcuse and Habermas's Political Ideas in English

2019 ◽  
pp. 215
Author(s):  
Asaad Abdullwahab AbdulKarim ◽  
Waleed Massaher Hamad ◽  
Salah Ibrahim Hamadi
Keyword(s):  
First Generation ◽  
Second Generation ◽  
Frankfurt School ◽  
Western Thought ◽  
Political Ideas ◽  
Important Impact

Abstract     The Frankfurt School is characterized by its critical nature and it is the result of the Marxist socialist thought as it contributed to the development of the German thought in particular and the Western thought in general through important ideas put forward by a number of pioneers in the various generations of the school and most notably through the leading pioneer in the first generation, Marcuse, and the leading pioneer of the second  generation, Habermas, whose political ideas had an important impact on global thinking and later became the basis of the attic of many critical ideas. In spite of the belief of the school members in the idea of the criticism of power and community, each had his own ideas that distinguish him from the others.

Pharmakotherapie update

2020 ◽  
Vol 25 (1) ◽  
pp. 23-32
Author(s):  
Gerd Laux
Keyword(s):  
First Generation ◽  
Second Generation ◽  
Therapeutische Maßnahmen ◽  
Second Generation Antipsychotics

Für die Therapie schizophrener Erkrankungen sind seit fast 60 Jahren Antipsychotika/Neuroleptika aufgrund ihrer antipsychotischen Wirkung von zentraler Bedeutung. Die Einteilung kann unter verschiedenen Gesichtspunkten erfolgen (chemische Struktur, neuroleptische Potenz, Rezeptorprofil), heute werden üblicherweise unterschieden typische (traditionelle, klassische, konventionelle) Antipsychotika der ersten Generation ‒ »First Generation Antipsychotics« (FGA) ‒ und sog. atypische (»neuere«) Neuroleptika bzw. Antipsychotika der zweiten Generation ‒»Second Generation Antipsychotics« (SGA). Hierzu zählen Aripiprazol, Asenapin, Cariprazin, Clozapin, Olanzapin, Quetiapin, Risperidon, Sertindol und Ziprasidon. Hierbei handelt es sich um keine homogene Gruppe – sowohl neuropharmakologisch (Wirkmechanismus), als auch hinsichtlich klinischem Wirkprofil und dem Nebenwirkungsspektrum bestehen z. T. erhebliche Unterschiede. Neben der Akut-Medikation ist eine Langzeitmedikation bzw. Rezidivprophylaxe mit Antipsychotika für die Rehabilitation vieler schizophrener Patienten im Sinne eines »Stresspuffers« von grundlegender Bedeutung. In Placebo-kontrollierten Studien trat bei Patienten, die über ein Jahr behandelt wurden, bei etwa 30% unter Neuroleptika ein Rezidiv auf, unter Placebo bei mehr als 70%. Für die Langzeitbehandlung bietet sich der Einsatz von Depot-Neuroleptika an, neu entwickelt wurden Langzeit-Depot-Injektionen mit Intervallen von bis zu 3 Monaten. Grundsätzlich ist die niedrigstmögliche (wirksame) Dosis zu verwenden. Im Zentrum der Nebenwirkungen (UAW) standen lange Zeit extrapyramidal-motorische Bewegungsstörungen (EPMS), mit der Einführung von Clozapin und anderen atypischen Antipsychotika der zweiten Generation gewannen andere Nebenwirkungen an Bedeutung. Hierzu zählen Gewichtszunahme, Störungen metabolischer Parameter und ein erhöhtes Risiko für Mortalität und zerebrovaskuläre Ereignisse bei älteren Patienten mit Demenz. Entsprechende Kontrolluntersuchungen sind erforderlich, für Clozapin gibt es aufgrund seines Agranulozytose-Risikos Sonderbestimmungen. Immer sollte ein Gesamtbehandlungsplan orientiert an der neuen S3-Praxisleitlinie Schizophrenie der DGPPN aufgestellt werden, der psychologische und milieu-/sozial-therapeutische Maßnahmen einschließt. Standard ist heute auch eine sog. Psychoedukation, für Psychopharmaka liegen bewährte Patienten-Ratgeber vor.

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