scholarly journals Model simulations of chemical effects of sprites in relation with satellite observations

2021 ◽  
Author(s):  
Holger Winkler ◽  
Takayoshi Yamada ◽  
Yasuko Kasai ◽  
Uwe Berger ◽  
Justus Notholt
Keyword(s):  
Dispersion Model ◽  
Plasma Chemistry ◽  
Water Molecules ◽  
Streamer Discharge ◽  
Model Simulations ◽  
Direct Observations ◽  
Chemical Effects ◽  
Production Of Hydrogen ◽  
Hydrogen Radicals ◽  
The Impact

Abstract. Recently, measurements by the Superconducting Submillimeter-Wave Limb Emission Sounder (SMILES) satellite instrument have been presented which indicate an increase of mesospheric HO2 above sprite producing thunderstorms. These are the first direct observations of chemical sprite effects, and provide an opportunity to test our understanding of the chemical processes in sprites. In the present paper, results of numerical model simulations are presented. A plasma chemistry model in combination with a vertical transport module was used to simulate the impact of a streamer discharge in the altitude range 70–80 km, corresponding to one of the observed sprite events. Additionally, a horizontal transport and dispersion model was used to simulate advection and expansion of the sprite volumes. The model simulations predict a production of hydrogen radicals mainly due to reactions of proton hydrates formed after the electrical discharge. The net effect is a conversion of water molecules into H + OH. This leads to increasing HO2 concentrations a few hours after the electric breakdown. According to the model simulations, the HO2 enhancements above sprite producing thunderstorms observed by the SMILES instrument can not solely be attributed to the detected one sprite event for each thunderstorm. The main reason is that the estimated amount of HO2 released by a sprite is much smaller than the observed increase. Furthermore, the advection and dispersion simulations of the observed sprites reveal that in most cases only little overlap of the expanded sprite volumes and the field of view of the SMILES measurements is expected.

scholarly journals Model simulations of chemical effects of sprites in relation with observed HO<sub>2</sub> enhancements over sprite-producing thunderstorms

2021 ◽  
Vol 21 (10) ◽  
pp. 7579-7596
Author(s):  
Holger Winkler ◽  
Takayoshi Yamada ◽  
Yasuko Kasai ◽  
Uwe Berger ◽  
Justus Notholt
Keyword(s):  
Dispersion Model ◽  
Plasma Chemistry ◽  
Water Molecules ◽  
Streamer Discharge ◽  
Air Masses ◽  
Model Simulations ◽  
Chemical Effects ◽  
Production Of Hydrogen ◽  
Hydrogen Radicals ◽  
The Impact

Abstract. Recently, measurements by the Superconducting Submillimeter-Wave Limb Emission Sounder (SMILES) satellite instrument have been presented which indicate an increase in mesospheric HO2 above sprite-producing thunderstorms. The aim of this paper is to compare these observations to model simulations of chemical sprite effects. A plasma chemistry model in combination with a vertical transport module was used to simulate the impact of a streamer discharge in the altitude range 70–80 km, corresponding to one of the observed sprite events. Additionally, a horizontal transport and dispersion model was used to simulate advection and expansion of the sprite air masses. The model simulations predict a production of hydrogen radicals mainly due to reactions of proton hydrates formed after the electrical discharge. The net effect is a conversion of water molecules into H+OH. This leads to increasing HO2 concentrations a few hours after the electric breakdown. Due to the modelled long-lasting increase in HO2 after a sprite discharge, an accumulation of HO2 produced by several sprites appears possible. However, the number of sprites needed to explain the observed HO2 enhancements is unrealistically large. At least for the lower measurement tangent heights, the production mechanism of HO2 predicted by the model might contribute to the observed enhancements.

HO2 enhancements due to sprite discharges - observations and model simulations

2020 ◽  
Author(s):  
Holger Winkler ◽  
Takayoshi Yamada ◽  
Yasuko Kasai ◽  
Justus Notholt
Keyword(s):  
Plasma Chemistry ◽  
Submillimeter Wave ◽  
Electrical Discharges ◽  
Model Simulations ◽  
Direct Observations

&lt;p&gt;We present first observational evidences of an HO&lt;sub&gt;2 &lt;/sub&gt;production in the mesosphere above sprite&amp;#8208;producing thunderstorms derived from low&amp;#8208;noise SMILES (Submillimeter-Wave Limb-Emission Sounder) observation spectra in relation with sprite detections by the ISUAL (Imager of Sprites and Upper Atmospheric Lightning) instrument. Three events were identified with enhanced HO&lt;sub&gt;2&lt;/sub&gt; levels of approximately 10&lt;sup&gt;25&lt;/sup&gt; molecules at altitudes of 75-80 km a few hours after sprite occurrence. These first direct observations of chemical sprite effects are compared to results of plasma chemistry model simulations of electrical discharges in the mesosphere, and processes which can lead to an increase of mesospheric HO&lt;sub&gt;2&lt;/sub&gt; on timescale of a few hours after a sprite event are analysed.&lt;/p&gt;

scholarly journals The Impact of the Electric Field on Surface Condensation of Water Vapor: Insight from Molecular Dynamics Simulation

Nanomaterials ◽  
2019 ◽  
Vol 9 (1) ◽  
pp. 64 ◽  
Author(s):  
Qin Wang ◽  
Hui Xie ◽  
Zhiming Hu ◽  
Chao Liu
Keyword(s):  
Molecular Dynamics ◽  
Water Vapor ◽  
Electric Field ◽  
Intermolecular Forces ◽  
Dynamics Simulation ◽  
Water Molecules ◽  
Attraction Force ◽  
Condensation Rate ◽  
Shape Transformation ◽  
The Impact

In this study, molecular dynamics simulations were carried out to study the coupling effect of electric field strength and surface wettability on the condensation process of water vapor. Our results show that an electric field can rotate water molecules upward and restrict condensation. Formed clusters are stretched to become columns above the threshold strength of the field, causing the condensation rate to drop quickly. The enhancement of surface attraction force boosts the rearrangement of water molecules adjacent to the surface and exaggerates the threshold value for shape transformation. In addition, the contact area between clusters and the surface increases with increasing amounts of surface attraction force, which raises the condensation efficiency. Thus, the condensation rate of water vapor on a surface under an electric field is determined by competition between intermolecular forces from the electric field and the surface.

scholarly journals A multilevel investigation supported by multivariate analysis for tomato product formulation

2021 ◽  
Author(s):  
Fatma Boukid ◽  
Elena Curti ◽  
Agoura Diantom ◽  
Eleonora Carini ◽  
Elena Vittadini
Keyword(s):  
Thermal Treatment ◽  
Color Change ◽  
Water Molecules ◽  
Thermal Treatments ◽  
Industrial Processing ◽  
H Nmr ◽  
Mobile Populations ◽  
Product Formulation ◽  
Tomato Product ◽  
The Impact

AbstractIndustrial processing of tomato includes its cutting and mincing, thermal treatments, and the addition of ingredients, which might induce changes in physicochemical properties of the final products. In this frame, the impact of texturing/thickening [xanthan gum (X) or potato fiber (F)] on the macroscopic, mesoscopic and molecular properties of tomato double concentrate (TDC) was investigated to determine if F can efficiently substitute X, in association with small solutes (sugar and salt) and thermal treatment (cold and hot). At a macroscopic level, multivariate statistics (MANOVA) underlined that color change (ΔE) was increased by X and F addition contrary to heating and the addition of salt and sugar. MANOVA revealed that texture was greatly enhanced through the use of F over X. 1H NMR molecular mobility changes were more controlled by texturing agents (F and X) than thermal treatment and small solutes. Particularly F increased the more rigid population indicating stronger interaction with water molecules resulting in shear-thinning flow. However, adding X contributed into the increase of the dynamic and mobile populations. Therefore, F can be a valid “clean label” substitute of X in modulating tomato products properties.

scholarly journals The Influence of Concentration and Temperature on the Membrane Resistance of Ion Exchange Membranes and the Levelised Cost of Hydrogen from Reverse Electrodialysis with Ammonium Bicarbonate

Membranes ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 135
Author(s):  
Yash Dharmendra Raka ◽  
Robert Bock ◽  
Håvard Karoliussen ◽  
Øivind Wilhelmsen ◽  
Odne Stokke Burheim
Keyword(s):  
Ion Exchange ◽  
Waste Heat ◽  
Ammonium Bicarbonate ◽  
Operating Efficiency ◽  
Membrane Thickness ◽  
Ion Exchange Membranes ◽  
Reverse Electrodialysis ◽  
Ohmic Resistance ◽  
Production Of Hydrogen ◽  
The Impact

The ohmic resistances of the anion and cation ion-exchange membranes (IEMs) that constitute a reverse electrodialysis system (RED) are of crucial importance for its performance. In this work, we study the influence of concentration (0.1 M, 0.5 M, 1 M and 2 M) of ammonium bicarbonate solutions on the ohmic resistances of ten commercial IEMs. We also studied the ohmic resistance at elevated temperature 313 K. Measurements have been performed with a direct two-electrode electrochemical impedance spectroscopy (EIS) method. As the ohmic resistance of the IEMs depends linearly on the membrane thickness, we measured the impedance for three different layered thicknesses, and the results were normalised. To gauge the role of the membrane resistances in the use of RED for production of hydrogen by use of waste heat, we used a thermodynamic and an economic model to study the impact of the ohmic resistance of the IEMs on hydrogen production rate, waste heat required, thermochemical conversion efficiency and the levelised cost of hydrogen. The highest performance was achieved with a stack made of FAS30 and CSO Type IEMs, producing hydrogen at 8.48× 10−7 kg mmem−2s−1 with a waste heat requirement of 344 kWh kg−1 hydrogen. This yielded an operating efficiency of 9.7% and a levelised cost of 7.80 € kgH2−1.

scholarly journals Enhanced hydrogen production of Rhodobacter sphaeroides promoted by extracellular H+ of Halobacterium salinarum

2021 ◽  
Vol 71 (1) ◽  
Author(s):  
Jiang-Yu Ye ◽  
Yue Pan ◽  
Yong Wang ◽  
Yi-Chao Wang
Keyword(s):  
Hydrogen Production ◽  
Production Rate ◽  
Rhodobacter Sphaeroides ◽  
Coupled System ◽  
Purple Membrane ◽  
Halobacterium Salinarum ◽  
Control Group ◽  
Hydrogen Production Rate ◽  
Production Of Hydrogen ◽  
The Impact

Abstract Purpose This study utilized the principle that the bacteriorhodopsin (BR) produced by Halobacterium salinarum could increase the hydrogen production of Rhodobacter sphaeroides. H. salinarum are co-cultured with R. sphaeroides to determine the impact of purple membrane fragments (PM) on R. sphaeroides and improve its hydrogen production capacity. Methods In this study, low-salinity in 14 % NaCl domesticates H salinarum. Then, 0–160 nmol of different concentration gradient groups of bacteriorhodopsin (BR) and R. sphaeroides was co-cultivated, and the hydrogen production and pH are measured; then, R. sphaeroides and immobilized BR of different concentrations are used to produce hydrogen to detect the amount of hydrogen. Two-chamber microbial hydrogen production system with proton exchange membrane-assisted proton flow was established, and the system was operated. As additional electricity added under 0.3 V, the hydrogen production rate increased with voltages in the coupled system. Results H salinarum can still grow well after low salt in 14% NaCl domestication. When the BR concentration is 80 nmol, the highest hydrogen production reached 217 mL per hour. Both immobilized PC (packed cells) and immobilized PM (purple membrane) of H. salinarum could promote hydrogen production of R. sphaeroides to some extent. The highest production of hydrogen was obtained by the coupled system with 40 nmol BR of immobilized PC, which increased from 127 to 232 mL, and the maximum H2 production rate was 18.2 mL−1 h−1 L culture. In the 192 h experiment time, when the potential is 0.3 V, the hydrogen production amount can reach 920 mL, which is 50.3% higher than the control group. Conclusions The stability of the system greatly improved after PC was immobilized, and the time for hydrogen production of R. sphaeroides significantly extended on same condition. As additional electricity added under 0.3 V, the hydrogen production rate increased with voltages in the coupled system. These results are helpful to build a hydrogen production-coupled system by nitrogenase of R. sphaeroides and proton pump of H. salinarum. Graphical abstract

Investigation of volcanic emissions in Antikythera PANGEA station using near-real-time alerts

2021 ◽  
Author(s):  
Anna Kampouri ◽  
Vassilis Amiridis ◽  
Stavros Solomos ◽  
Anna Gialitaki ◽  
Eleni Marinou ◽  
...  
Keyword(s):  
Real Time ◽  
Dispersion Model ◽  
Atmospheric Composition ◽  
Dust Particles ◽  
Volcanic Plume ◽  
Observation Data ◽  
National Observatory ◽  
Development Fund ◽  
Model Simulations ◽  
Geophysical Observatory

&lt;p&gt;In the last years, several Etna eruption events are documented, forming lava flows and explosive activity. The Pilot EO4D_ash &amp;#8211; Earth observation data for detection, discrimination &amp; distribution (4D) of volcanic ash of the e-shape project provides the PANhellenic GEophysical observatory of Antikythera (PANGEA) of the National Observatory of Athens (NOA), in Greece with near-real-time alerts from Etna volcano eruptions. These alerts are used in the PANGEA station to monitor and reveal the presence of volcanic particles above the area the days following an eruption, also the station is supported by a volcanic particle monitoring and forecasting warning system. In this work, we investigate the volcano eruption between 30 May and 6 June 2019 which affected the southern parts of Greece and reaching the Antikythera station. Due to the prevailing meteorological conditions, volcanic particles and gases followed an easterly direction and were dispersed towards Greece. FLEXPART dispersion model simulations confirm the volcanic plume transport from Etna towards PANGEA, mixing also with co-existing desert dust particles. Model simulations are evaluated with Polly&lt;sup&gt;XT&lt;/sup&gt; lidar measurements performed at PANGEA and satellite-based SO&lt;sub&gt;2&lt;/sub&gt; observations from the TROPOspheric Monitoring Instrument onboard the Sentinel-5 Precursor (TROPOMI/S5P). This is the first time that Etna volcanic products are monitored at the Antikythera station, in Greece with implications for the investigation of their role in the Mediterranean weather and climate.&lt;/p&gt;&lt;p&gt;&lt;strong&gt;Acknowledgments&lt;/strong&gt;: We acknowledge the support by EU H2020 E-shape project (Grant Agreement n. 820852). Also, this research was supported by data and services obtained from the PANhellenic Geophysical Observatory of Antikythera (PANGEA) of the National Observatory of Athens (NOA), Greece, and by the project &amp;#8220;PANhellenic infrastructure for Atmospheric Composition and climatE change&amp;#8221; (MIS 5021516) which is implemented under the Action &amp;#8220;Reinforcement of the Research and Innovation Infrastructure&amp;#8221;, funded by the Operational Programme &quot;Competitiveness, Entrepreneurship and Innovation&quot; (NSRF 2014-2020) and co-financed by Greece and the European Union (European Regional Development Fund). NOA team acknowledges the support of the Stavros Niarchos Foundation (SNF).&lt;/p&gt;

Ozone Production With Plasma Discharge: Comparisons Between Activated Air and Activated Fuel/Air Mixture

2021 ◽  
Author(s):  
Ghazanfar Mehdi ◽  
Maria Grazia De Giorgi ◽  
Donato Fontanarosa ◽  
Sara Bonuso ◽  
Antonio Ficarella
Keyword(s):  
Experimental Data ◽  
Plasma Chemistry ◽  
Kinetic Scheme ◽  
Plasma Discharge ◽  
Chemical Kinetic ◽  
Ozone Production ◽  
Air Plasma ◽  
Flammability Limits ◽  
Combustion Enhancement ◽  
The Impact

Abstract This study focused on the comparative analysis about the production of ozone and active radicals in presence of nanopulsed plasma discharge on air and on fuel/air mixture to investigate its effect on combustion enhancement. This analysis is based on numerical modeling of air and methane/air plasma discharge with different repetition rates (100 Hz, 1000 Hz and 10000 Hz). To this purpose, a two-step approach has been proposed based on two different chemistry solvers: a 0-D plasma chemistry solver (ZDPlasKin toolbox) and a combustion chemistry solver (CHEMKIN software suite). Consequently, a comprehensive chemical kinetic scheme was generated including both plasma excitation reactions and gas phase reactions. Validation of air and methane/air mechanisms was performed with experimental data. Kinetic models of both air and methane/air provides good fitting with experimental data of O atom generation and decay process. ZDPlasKin results were introduced in CHEMKIN in order to analyze combustion enhancement. It was found that the concentrations of O3 and O atom in air are higher than the methane/air activation. However, during the air activation peak concentration of ozone was significantly increased with repetition rates and maximum was observed at 10000 Hz. Furthermore, ignition timings and flammability limits were also improved with air and methane/air activation but the impact of methane/air activation was comparatively higher.

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