Characterization of aerosol photooxidation flow reactors:  heterogeneous oxidation, secondary organic aerosol formation and cloud  condensation nuclei activity measurements

Lambe, Andrew T.; Ahern, Adam; Williams, Leah R.; Slowik, Jay G.; Wong, J. P. S.; Abbatt, Jonathan P. D.; Brune, W. H.; Ng, N. L.; Croasdale, D. R.; Wright, Justin P.; Worsnop, D. R.; Davidovits, P.; Onasch, T. B.

doi:10.5194/amtd-3-5211-2010

Cited by 72 publications

(136 citation statements)

References 46 publications

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“…Thus, the in-chip residence time, equivalent to incubation in a biochemical reaction, is characterised by a non-Gaussian distribution instead of a sharp peak which is, on average, equal to the nominal time but tends to be significantly longer for a subpopulation of reactions. Indeed, computational fluid dynamics simulations (Supp Figure 5D) and particle tracing predicted a characteristic residence time distribution as expected by the Taylor dispersion in laminar flow 50,51 (Supp Figure 5E). These results are in good overall agreement with the observed filament length distribution (Figure 5D) and suggest that errors due to residence time scattering in the microfluidic chip are likely to be the dominant source of inaccuracies in time-resolution experiments conducted with this or similar systems.…”

Section: Trapping Pre-steady State Kinetic Intermediates By Cryo-emsupporting

confidence: 53%

Visual Biochemistry: modular microfluidics enables kinetic insight from time-resolved cryo-EM

Mäeots

Lee

Nans

et al. 2020

Preprint

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Mechanistic understanding of biochemical reactions requires structural and kinetic characterization of the underlying chemical processes. However, no single experimental technique can provide this information in a broadly applicable manner and thus structural studies of static macromolecules are often complemented by biophysical analysis. Moreover, the common strategy of utilizing mutants or crosslinking probes to stabilize otherwise shortlived reaction intermediates is prone to trapping off-pathway artefacts and precludes determining the order of molecular events. To overcome these limitations and allow visualisation of biochemical processes at near-atomic spatial resolution and millisecond time scales, we developed a time-resolved sample preparation method for cryo-electron microscopy (trEM). We integrated a modular microfluidic device, featuring a 3D-mixing unit and a delay line of variable length, with a gas-assisted nozzle and motorised plunge-freeze set-up that enables automated, fast, and blot-free sample vitrification. This sample preparation not only preserves high-resolution structural detail but also substantially improves protein distribution across the vitreous ice. We validated the method by examining the formation of RecA filaments on single-stranded DNA. We could reliably visualise reaction intermediates of early filament growth across three orders of magnitude on sub-second timescales. Quantification of the trEM data allowed us to characterize the kinetics of RecA filament growth. The trEM method reported here is versatile, easy to reproduce and thus readily adaptable to a broad spectrum of fundamental questions in biology.

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Section: Trapping Pre-steady State Kinetic Intermediates By Cryo-emsupporting

confidence: 53%

Visual Biochemistry: modular microfluidics enables kinetic insight from time-resolved cryo-EM

Mäeots

Lee

Nans

et al. 2020

Preprint

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“…The average gas‐phase species residence time in the PAM reactor was approximately 100 s. The OH exposure, which is the product of the OH concentration and the average residence time in the PAM reactor, was obtained indirectly by measuring the decay of SO 2 due to reaction with OH. The OH concentration was varied by changing the UV light intensity through stepping the lamp voltages between 0 and 110 V. SO 2 calibration measurements were conducted as a function of UV lamp intensity and O 3 concentration [ Lambe et al , 2011b].…”

Section: Methodsmentioning

confidence: 99%

The deposition ice nucleation and immersion freezing potential of amorphous secondary organic aerosol: Pathways for ice and mixed‐phase cloud formation

Wang¹,

Lambe²,

Massoli³

et al. 2012

J. Geophys. Res.

197

299

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[1] Secondary organic aerosol (SOA) generated from the oxidation of organic gases are ubiquitous in the atmosphere, but their interaction with water vapor and their ice cloud formation potential at low temperatures remains highly uncertain. We report on onset conditions of water uptake and ice nucleation by amorphous SOA particles generated from the oxidation of naphthalene with OH radicals. Water uptake above 230 K was governed by the oxidation level of the SOA particles expressed as oxygen-to-carbon (O/C) ratio, followed by moisture-induced phase transitions and immersion freezing. For temperatures from 200 to 230 K, SOA particles nucleated ice via deposition mode from supersaturated water vapor independent of O/C ratio at relative humidity with respect to ice (RH ice ) $10-15% below homogeneous ice nucleation limits. The glass transition temperature (T g ) for the amorphous SOA particles was derived as a function of two parameters: (1) relative humidity (RH) with respect to water and (2) oxidation level of the SOA. The data show that particle phase and viscosity govern the particles' response to temperature and RH and provide a straightforward interpretation for the observed different heterogeneous ice nucleation pathways and water uptake by the laboratory-generated SOA and field-collected particles. Since SOA particles undergo glass transitions, these observations suggest that atmospheric SOA are potentially important for ice cloud formation and climate.

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“…SOA can absorb or scatter light [Laskin et al, 2015;Moise et al, 2015] and acts as cloud condensation nuclei (CCN) [Farmer et al, 2015]. The latter has been demonstrated by several laboratory studies for various biogenic and anthropogenic precursors [Alfarra et al, 2013;Asa-Awuku et al, 2009;Duplissy et al, 2008;Engelhart et al, 2008Engelhart et al, , 2011Frosch et al, 2011;Hartz et al, 2006;Juranyi et al, 2009;King et al, 2009;Kreidenweis et al, 2006;Lambe et al, 2011aLambe et al, , 2011bMassoli et al, 2010;Petters et al, 2009;Prenni et al, 2007;VanReken et al, 2005;Wex et al, 2009]. Therefore, SOA can affect climate by modifying the Earth's radiative budget and influencing cloud properties [Intergovernmental Panel on Climate Change, 2013].…”

Section: Introductionmentioning

confidence: 99%

Size‐dependent hygroscopicity parameter (κ) and chemical composition of secondary organic cloud condensation nuclei

Zhao

Buchholz

Kortner

et al. 2015

Geophysical Research Letters

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Secondary organic aerosol components (SOA) contribute significantly to the activation of cloud condensation nuclei (CCN) in the atmosphere. The CCN activity of internally mixed submicron SOA particles is often parameterized assuming a size‐independent single‐hygroscopicity parameter κ. In the experiments done in a large atmospheric reactor (SAPHIR, Simulation of Atmospheric PHotochemistry In a large Reaction chamber, Jülich), we consistently observed size‐dependent κ and particle composition for SOA from different precursors in the size range of 50 nm–200 nm. Smaller particles had higher κ and a higher degree of oxidation, although all particles were formed from the same reaction mixture. Since decreasing volatility and increasing hygroscopicity often covary with the degree of oxidation, the size dependence of composition and hence of CCN activity can be understood by enrichment of higher oxygenated, low‐volatility hygroscopic compounds in smaller particles. Neglecting the size dependence of κ can lead to significant bias in the prediction of the activated fraction of particles during cloud formation.

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Characterization of aerosol photooxidation flow reactors: heterogeneous oxidation, secondary organic aerosol formation and cloud condensation nuclei activity measurements

Cited by 72 publications

References 46 publications

Visual Biochemistry: modular microfluidics enables kinetic insight from time-resolved cryo-EM

Visual Biochemistry: modular microfluidics enables kinetic insight from time-resolved cryo-EM

The deposition ice nucleation and immersion freezing potential of amorphous secondary organic aerosol: Pathways for ice and mixed‐phase cloud formation

Size‐dependent hygroscopicity parameter (κ) and chemical composition of secondary organic cloud condensation nuclei

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