1,576 research outputs found
Catalytic Performance of Calcium-Lanthanum co-doped Ceria (Ce0.85-xLa0.15CaxO2-δ) in Partial Oxidation of Methane
In this study, Ce0.85-xLa0.15CaxO2-δ was synthesized using sol-gel combustion method and appliedfor partial oxidation of methane (POM). The physicochemical properties of catalyst were analyzed using X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS) and thermogravimetric analysis (TGA). Material shows a pure cubical structure and is highly stable up to 850 °C. The performance testing indicated the conversion of CH4 is 65% and selectivity of H2 and CO are 28% and 8%, respectively. The performance indicated the catalyst has a potential to be used for partial oxidation of methane on a larger scale. Copyright © 2021 by Authors, Published by BCREC Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0).
Investigating the variation of benzene and 1,3 butadiene in the UK during 2000–2020
The concentrations of benzene and 1,3-butadiene in urban, suburban, and rural sites of the U.K.
were investigated across 20 years (2000–2020) to assess the impacts of pollution control strategies. Given
the known toxicity of these pollutants, it is necessary to investigate national long-term trends across a
range of site types. We conclude that whilst legislative intervention has been successful in reducing
benzene and 1,3-butadiene pollution from vehicular sources, previously overlooked sources must now
be considered as they begin to dominate in contribution to ambient pollution. Benzene concentrations in
urban areaswere found to be ~5-fold greater than those in rural areas,whilst 1,3-butadiene concentrations
were up to ~10-fold greater
Abundance of no3 derived organo-nitrates and their importance in the atmosphere
The chemistry of the nitrate radical and its contribution to organo-nitrate formation in
the troposphere has been investigated using a mesoscale 3-D chemistry and transport model, WRFChem-CRI. The model-measurement comparisons of NO2
, ozone and night-time N2O5 mixing
ratios show good agreement supporting the model’s ability to represent nitrate (NO3
) chemistry
reasonably. Thirty-nine organo-nitrates in the model are formed exclusively either from the reaction
of RO2 with NO or by the reaction of NO3 with alkenes. Temporal analysis highlighted a significant
contribution of NO3
-derived organo-nitrates, even during daylight hours. Night-time NO3
-derived
organo-nitrates were found to be 3-fold higher than that in the daytime. The reactivity of daytime
NO3 could be more competitive than previously thought, with losses due to reaction with VOCs
(and subsequent organo-nitrate formation) likely to be just as important as photolysis. This has
highlighted the significance of NO3
in daytime organo-nitrate formation, with potential implications
for air quality, climate and human health. Estimated atmospheric lifetimes of organo-nitrates showed
that the organo-nitrates act as NOx reservoirs, with particularly short-lived species impacting on air
quality as contributors to downwind ozone formation
Mimo antenna system for modern 5g handheld devices with healthcare and high rate delivery
In this work, a new prototype of the eight-element MIMO antenna system for 5G communications, internet of things, and networks has been proposed. This system is based on an H-shaped monopole antenna system that offers 200 MHz bandwidth ranges between 3.4-3.6 GHz, and the isolation between any two elements is well below -12 dB without using any decoupling structure. The proposed system is designed on a commercially available 0.8 mm-thick FR4 substrate. One side of the chassis is used to place the radiating elements, while the copper from the other side is being removed to avoid short-circuiting with other components and devices. This also enables space for other systems, sub-systems, and components. A prototype is fabricated and excellent agreement is observed between the experimental and the computed results. It was found that ECC is 0.2 for any two radiating elements which is consistent with the desirable standards, and channel capacity is 38 bps/Hz which is 2.9 times higher than 4 x 4 MIMO configuration. In addition, single hand mode and dual hand mode analysis are conducted to understand the operation of the system under such operations and to identify losses and/or changes in the key performance parameters. Based on the results, the proposed antenna system will find its applications in modern 5G handheld devices and internet of things with healthcare and high rate delivery. Besides that, its design simplicity will make it applicable for mass production to be used in industrial demands
Reaction of Perfluorooctanoic Acid with Criegee Intermediates and Implications for the Atmospheric Fate of Perfluorocarboxylic Acids
The reaction of perfluorooctanoic
acid with the smallest carbonyl
oxide Criegee intermediate, CH<sub>2</sub>OO, has been measured and
is very rapid, with a rate coefficient of (4.9 ± 0.8) ×
10<sup>–10</sup> cm<sup>3</sup> s<sup>–1</sup>, similar
to that for reactions of Criegee intermediates with other organic
acids. Evidence is shown for the formation of hydroperoxymethyl perfluorooctanoate
as a product. With such a large rate coefficient, reaction with Criegee
intermediates can be a substantial contributor to atmospheric removal
of perfluorocarboxylic acids. However, the atmospheric fates of the
ester product largely regenerate the initial acid reactant. Wet deposition
regenerates the perfluorocarboxylic acid via condensed-phase hydrolysis.
Gas-phase reaction with OH is expected principally to result in formation
of the acid anhydride, which also hydrolyzes to regenerate the acid,
although a minor channel could lead to destruction of the perfluorinated
backbone
Abundance of NO 3 Derived Organo-Nitrates and Their Importance in the Atmosphere
From MDPI via Jisc Publications RouterHistory: accepted 2021-10-20, pub-electronic 2021-10-22Publication status: PublishedFunder: Natural Environment Research Council; Grant(s): NE/K004905/1The chemistry of the nitrate radical and its contribution to organo-nitrate formation in the troposphere has been investigated using a mesoscale 3-D chemistry and transport model, WRF-Chem-CRI. The model-measurement comparisons of NO2, ozone and night-time N2O5 mixing ratios show good agreement supporting the model’s ability to represent nitrate (NO3) chemistry reasonably. Thirty-nine organo-nitrates in the model are formed exclusively either from the reaction of RO2 with NO or by the reaction of NO3 with alkenes. Temporal analysis highlighted a significant contribution of NO3-derived organo-nitrates, even during daylight hours. Night-time NO3-derived organo-nitrates were found to be 3-fold higher than that in the daytime. The reactivity of daytime NO3 could be more competitive than previously thought, with losses due to reaction with VOCs (and subsequent organo-nitrate formation) likely to be just as important as photolysis. This has highlighted the significance of NO3 in daytime organo-nitrate formation, with potential implications for air quality, climate and human health. Estimated atmospheric lifetimes of organo-nitrates showed that the organo-nitrates act as NOx reservoirs, with particularly short-lived species impacting on air quality as contributors to downwind ozone formation
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