Multifunctional products of isoprene oxidation in polluted atmosphere and their contribution to SOA

<div>Acid-driven multiphase chemistry of isoprene epoxydiols (IEPOX), a key isoprene oxidation product, with inorganic sulfate aerosol yields substantial amounts of secondary organic aerosol (SOA) through the formation of organosulfur. The extent and implications of inorganic-to-organic sulfate conversion, however, are unknown. Herein, we reveal that extensive consumption of inorganic sulfate occurs, which increases with the IEPOX-to-inorganic sulfate ratio (IEPOX:Sulf<sub>inorg</sub>), as determined by laboratory and field measurements. We further demonstrate that organosulfur greatly modifies critical aerosol properties, such as acidity, morphology, viscosity, and phase state. These new mechanistic insights reveal that changes in SO<sub>2</sub> emissions, especially in isoprene-dominated environments, will significantly alter biogenic SOA physicochemical properties. Consequently, IEPOX:Sulf<sub>inorg</sub> will play a central role in understanding historical climate and determining future impacts of biogenic SOA on global climate and air quality.</div>

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Thermal and Quasi-Static Mechanical Characterization of Polyamide 6-Graphene Nanoplatelets Composites

Nanomaterials ◽

10.3390/nano11061454 ◽

2021 ◽

Vol 11 (6) ◽

pp. 1454

Author(s):

Pietro Russo ◽

Francesca Cimino ◽

Antonio Tufano ◽

Francesco Fabbrocino

Keyword(s):

Chemical Resistance ◽

Experimental Tests ◽

Polyamide 6 ◽

Graphene Nanoplatelets ◽

Strength Parameter ◽

Melt Compounding ◽

Static Mechanical ◽

Thermal And Electrical Properties ◽

Multifunctional Products

The growing demand for lightweight and multifunctional products in numerous industrial fields has recently fuelled a growing interest in the development of materials based on polymer matrices including graphene-like particles, intrinsically characterized by outstanding mechanical, thermal, and electrical properties. Specifically, with regard to one of the main mass sectors, which is the automotive, there has been a significant increase in the use of reinforced polyamides for underhood applications and fuel systems thanks to their thermal and chemical resistance. In this frame, polyamide 6 (PA6) composites filled with graphene nanoplatelets (GNPs) were obtained by melt-compounding and compared in terms of thermal and mechanical properties with the neat matrix processed under the same condition. The results of the experimental tests have shown that the formulations studied so far offer slight improvements in terms of thermal stability but much more appreciable benefits regarding both tensile and flexural parameters with respect to the reference material. Among these effects, the influence of the filler content on the strength parameter is noteworthy. However, the predictable worsening of the graphene sheet dispersion for GNPs contents greater than 3%, as witnessed by scanning electron images of the tensile fractured sections of specimens, affected the ultimate performance of the more concentrated formulation.

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The heavily polluted atmosphere of the DAZ white dwarf GALEX J193156.8+011745

Monthly Notices of the Royal Astronomical Society Letters ◽

10.1111/j.1745-3933.2010.00830.x ◽

2010 ◽

Vol 404 (1) ◽

pp. L40-L44 ◽

Cited By ~ 36

Author(s):

S. Vennes ◽

A. Kawka ◽

P. Németh

Keyword(s):

White Dwarf ◽

Polluted Atmosphere

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Non-Motorized Transportation Analysis of Traffic Density, Pollution Using Regression Anova Analysis

International Journal of Scientific Research in Science and Technology ◽

10.32628/ijsrst218474 ◽

2021 ◽

pp. 534-542

Author(s):

Arjun Rajeevkumar Bhele ◽

Dr. Sujesh D. Ghodmare

Keyword(s):

Air Pollution ◽

Environmental Issues ◽

Economic Benefits ◽

Urban Transport ◽

Traffic Density ◽

Urban Mobility ◽

Polluted Atmosphere ◽

Transportation Modes ◽

Prolonged Duration ◽

Motorized Transport

Planners are now trying to provide greener travel solutions to reduce fiscal, social, and environmental issues. This research, therefore, seeks to find significant reasons for urban transport to enhance the use of alternative transportation modes. This report seeks to establish the connection between influential metrics for urban mobility and regular travel trips from different parts of the world. Deployment of excellent non-motorized transport facilities for Walking and cycling is a good way to encourage the use of bicycles, thereby increasing the physical fitness of end-users. Past studies were thoroughly reviewed and found to be applicable for analysis and application in the real world. Anova's regression analysis is distinguished by a more comprehensive interpretation of the findings. At Rajkamal Intersection, Amravati district, Maharashtra the traffic volume counts were carried out. It is the focus of the transport congestion, which leads to a polluted atmosphere due to prolonged duration at the signals. In this research, it can be seen that with the use of Motorized transport the traffic density & air pollution will increase with time, and with the increase in the use of Non-Motorized transport, the traffic density decreases also the air pollution is at a steady pace. The current study shows the necessity, favourable conditions, and economic benefits of non-motorized sustainable traffic, in the Indian condition.

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Explicit modeling of volatile organic compounds partitioning in the atmospheric aqueous phase

Atmospheric Chemistry and Physics ◽

10.5194/acp-13-1023-2013 ◽

2013 ◽

Vol 13 (2) ◽

pp. 1023-1037 ◽

Cited By ~ 30

Author(s):

C. Mouchel-Vallon ◽

P. Bräuer ◽

M. Camredon ◽

R. Valorso ◽

S. Madronich ◽

...

Keyword(s):

Organic Matter ◽

Dissolved Organic Matter ◽

Water Content ◽

Gas Phase ◽

Aqueous Phase ◽

Water Soluble ◽

Chemical Mechanism ◽

Organic Species ◽

Cloud Water Content ◽

Isoprene Oxidation

Abstract. The gas phase oxidation of organic species is a multigenerational process involving a large number of secondary compounds. Most secondary organic species are water-soluble multifunctional oxygenated molecules. The fully explicit chemical mechanism GECKO-A (Generator of Explicit Chemistry and Kinetics of Organics in the Atmosphere) is used to describe the oxidation of organics in the gas phase and their mass transfer to the aqueous phase. The oxidation of three hydrocarbons of atmospheric interest (isoprene, octane and α-pinene) is investigated for various NOx conditions. The simulated oxidative trajectories are examined in a new two dimensional space defined by the mean oxidation state and the solubility. The amount of dissolved organic matter was found to be very low (yield less than 2% on carbon atom basis) under a water content typical of deliquescent aerosols. For cloud water content, 50% (isoprene oxidation) to 70% (octane oxidation) of the carbon atoms are found in the aqueous phase after the removal of the parent hydrocarbons for low NOx conditions. For high NOx conditions, this ratio is only 5% in the isoprene oxidation case, but remains large for α-pinene and octane oxidation cases (40% and 60%, respectively). Although the model does not yet include chemical reactions in the aqueous phase, much of this dissolved organic matter should be processed in cloud drops and modify both oxidation rates and the speciation of organic species.

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High-resolution inversion of OMI formaldehyde columns to quantify isoprene emission on ecosystem-relevant scales: application to the southeast US

Atmospheric Chemistry and Physics ◽

10.5194/acp-18-5483-2018 ◽

2018 ◽

Vol 18 (8) ◽

pp. 5483-5497 ◽

Cited By ~ 21

Author(s):

Jennifer Kaiser ◽

Daniel J. Jacob ◽

Lei Zhu ◽

Katherine R. Travis ◽

Jenny A. Fisher ◽

...

Keyword(s):

High Resolution ◽

Land Cover ◽

Satellite Data ◽

Data Uncertainty ◽

Emission Inventories ◽

Model Errors ◽

Atmospheric Models ◽

Isoprene Emission ◽

Isoprene Oxidation ◽

Southeast Us

Abstract. Isoprene emissions from vegetation have a large effect on atmospheric chemistry and air quality. “Bottom-up” isoprene emission inventories used in atmospheric models are based on limited vegetation information and uncertain land cover data, leading to potentially large errors. Satellite observations of atmospheric formaldehyde (HCHO), a high-yield isoprene oxidation product, provide “top-down” information to evaluate isoprene emission inventories through inverse analyses. Past inverse analyses have however been hampered by uncertainty in the HCHO satellite data, uncertainty in the time- and NOx-dependent yield of HCHO from isoprene oxidation, and coarse resolution of the atmospheric models used for the inversion. Here we demonstrate the ability to use HCHO satellite data from OMI in a high-resolution inversion to constrain isoprene emissions on ecosystem-relevant scales. The inversion uses the adjoint of the GEOS-Chem chemical transport model at 0.25∘ × 0.3125∘ horizontal resolution to interpret observations over the southeast US in August–September 2013. It takes advantage of concurrent NASA SEAC4RS aircraft observations of isoprene and its oxidation products including HCHO to validate the OMI HCHO data over the region, test the GEOS-Chem isoprene oxidation mechanism and NOx environment, and independently evaluate the inversion. This evaluation shows in particular that local model errors in NOx concentrations propagate to biases in inferring isoprene emissions from HCHO data. It is thus essential to correct model NOx biases, which was done here using SEAC4RS observations but can be done more generally using satellite NO2 data concurrently with HCHO. We find in our inversion that isoprene emissions from the widely used MEGAN v2.1 inventory are biased high over the southeast US by 40 % on average, although the broad-scale distributions are correct including maximum emissions in Arkansas/Louisiana and high base emission factors in the oak-covered Ozarks of southeast Missouri. A particularly large discrepancy is in the Edwards Plateau of central Texas where MEGAN v2.1 is too high by a factor of 3, possibly reflecting errors in land cover. The lower isoprene emissions inferred from our inversion, when implemented into GEOS-Chem, decrease surface ozone over the southeast US by 1–3 ppb and decrease the isoprene contribution to organic aerosol from 40 to 20 %.

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