Endothelial dysfunction, oxidative stress and low-grade endotoxemia in COVID-19 patients hospitalised in medical wards.

BACKGROUND: Endothelial dysfunction, assessed by flow-mediated dilation (FMD), is related to poor prognosis in patients with COVID-19 pneumonia (CP). In this study, we explored the interplay among FMD, NADPH oxidase type 2 (NOX-2) and lipopolysaccharides (LPS) in hospitalised patients with CP, community acquired pneumonia (CAP) and controls (CT). METHODS: We enrolled 20 consecutive patients with CP, 20 hospitalised patients with CAP and 20 CT matched for sex, age, and main cardiovascular risk factors. In all subjects we performed FMD and collected blood samples to analyse markers of oxidative stress (soluble Nox2-derived peptide (sNOX2-dp), hydrogen peroxide breakdown activity (HBA), nitric oxide (NO), hydrogen peroxide (H2O2)), inflammation (TNF-α and IL-6), LPS and zonulin levels. RESULTS: Compared with controls, CP had significant higher values of LPS, sNOX-2-dp, H2O2,TNF-α, IL-6 and zonulin; conversely FMD, HBA and NO bioavailability were significantly lower in CP. Compared to CAP patients, CP had significantly higher levels of sNOX2-dp, H2O2, TNF-α, IL-6, LPS, zonulin and lower HBA. Simple linear regression analysis showed that FMD inversely correlated with sNOX2-dp, H2O2, TNF-α, IL-6, LPS and zonulin; conversely FMD was directly correlated with NO bioavailability and HBA. Multiple linear regression analysis highlighted LPS as the only predictor of FMD. CONCLUSION: This study shows that patients with COVID-19 have low-grade endotoxemia that could activate NOX-2, generating increased oxidative stress and endothelial dysfunction.

Robust therapeutic effects on COVID-19 of novel small molecules: Alleviation of SARS-CoV-2 S protein induction of ACE2/TMPRSS2, NOX2/ROS, and MCP-1.

While new variants of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) constantly emerge to prolong the pandemic of COVID-19, robust and safe therapeutics are in urgent need. During the previous and ongoing fight against the pandemic in China, Traditional Chinese Medicine (TCM) has proven to be markedly effective in treating COVID-19. Among active ingredients of TCM recipes, small molecules such as quercetin, glabridin, gallic acid, and chrysoeriol have been predicted to target viral receptor angiotensin-converting enzyme 2 (ACE2) via system pharmacology/molecular docking/visualization analyses. Of note, endothelial dysfunction induced by oxidative stress and inflammation represents a critical mediator of acute respiratory distress syndrome (ARDS) and multi-organ injuries in patients with COVID-19. Hence, in the present study, we examined whether quercetin, glabridin, gallic acide and chrysoeriol regulate viral receptors of ACE2 and transmembrane serine protease 2 (TMPRSS2), redox modulator NADPH oxidase isoform 2 (NOX2), and inflammatory protein of monocyte chemoattractant protein-1 (MCP-1) in endothelial cells to mediate therapeutic protection against COVID-19. Indeed, quercetin, glabridin, gallic acide and chrysoeriol completely attenuated SARS-CoV-2 spike protein (S protein)-induced upregulation in ACE2 protein expression in endothelial cells. In addition, these small molecules abolished S protein upregulation of cleaved/active form of TMPRSS2, while native TMPRSS2 was not significantly regulated. Moreover, these small molecules completely abrogated S protein-induced upregulation in NOX2 protein expression, which resulted in alleviated superoxide production, confirming their preventive efficacies against S protein-induced oxidative stress in endothelial cells. In addition, treatment with these small molecules abolished S protein induction of MCP-1 expression. Collectively, our findings for the first time demonstrate that these novel small molecules may be used as novel and robust therapeutic options for the treatment of patients with COVID-19, via effective attenuation of S protein induction of endothelial oxidative stress and inflammation.

A Comparative Study of Pollution Levels in Major Cities of India During Covid-19 in India

This paper aims to study the major pollutants of the four metro cities of India before and after covid 19 first wave. The cities considered for the study are Bangalore, Delhi, Mumbai, and Kolkata. The major pollutants considered for the study are PM2.5, PM10, NO, NO2, NOx, SO2, CO, and Ozone. The basic aim of the study is to find the effect of lockdown and covid restrictions on the level of pollutants across the four major cities of India. We used both parametric and non-parametric tests for the analysis using SPSS. From the study, it is clear that there is a significant decrease in all the major pollutants across India's major cities.6. © 2023, University of Wollongong. All rights reserved.

Investigation of Changes in Atmospheric Pollutants due to the Cessation of Anthropogenic Activities: Spatial Heterogeneity and Complex Atmospheric Chemistry

The current study examines the air quality trends in response to Covid-19-induced lockdowns at various locations in Delhi. The primary pollutants like NO2, CO, and PM10 have shown reductions during the lockdown phase, but the magnitude varied significantly in different places. Also, during the lockdown, air quality in some areas of Delhi exceeded National Ambient Air Quality Standards. Secondary pollutants like O3 have shown mixed trends due to complex atmospheric processes and dependence on relative proportions of VOC and NOx levels. A total of six sites, including traffic, industrial, and residential sites, have been studied. The diurnal behavior of pollutants also differed significantly around different places. During the lockdown, Ashok Vihar, a traffic-influenced area, showed a decrease in O3 (~ 40%), while at DTU (Traffic site), O3 levels increased (~ 48%). The industrial sites Okhla and Wazirpur also showed different trends during the lockdown;O3 in Wazirpur decreased by 50%, whereas Okhla increased by 25%. NOx concentration was lesser in 2020 at all the stations compared to 2019, indicating the positive impact of the lockdown on air pollution due to vehicular emissions. The Approximate Envelope Method estimates the secondary fraction of PM2.5. This fraction of PM is dominated in the lockdown year in the residential site, while it remains unchanged in the traffic site and increased by 11% in the industrial area. Despite being not so far from each other, these sites show very different patterns of pollutants during lockdown episodes. © 2023, The Author(s) under exclusive licence to Institute of Earth Environment, Chinese Academy Sciences.

On the transition of major pollutant and O3 production regime during Covid-19 lockdowns.

Lockdowns enforced amid the pandemic facilitated the evaluation of the impact of emission reductions on air quality and the production regime of O3 under NOx reduction. Analysis of space-time variation of various pollutants (PM10, PM2.5, NOx, CO, O3 and VOC or TNMHC) through the lockdown phases at eight typical stations (Urban/Metro, Rural/high vegetation and coastal) is carried out. It reveals how the major pollutant (PM10 or PM2.5 or O3, or CO) differs from station to station as lockdowns progress depending on geography, land-use pattern and efficacy of lockdown implementation. Among the stations analyzed, Delhi (Chandnichowk), the most polluted (PM10 = 203 µgm-3; O3 = 17.4 ppbv) in pre-lockdown, experienced maximum reduction during the first phase of lockdown in PM2.5 (-47%), NO2 (-40%), CO (-37%) while O3 remained almost the same (2% reduction) to pre-lockdown levels. The least polluted Mahabaleshwar (PM10 = 45 µgm-3; O3 = 54 ppbv) witnessed relatively less reduction in PM2.5 (-2.9%), NO2 (-4.7%), CO (-49%) while O3 increased by 36% to pre-lockdown levels. In rural stations with lots of greenery, O3 is the major pollutant attributed to biogenic VOC emissions from vegetation besides lower NO levels. In other stations, PM2.5 or PM10 is the primary pollutant. At Chennai, Jabalpur, Mahabaleshwar and Goa, the deciding factor of Air Quality Index (AQI) remained unchanged, with reduced values. Particulate matter, PM10 decided AQI for three stations (dust as control component), and PM2.5 decided the same for two but within acceptable limits for stations. Improvement of AQI through control of dust would prove beneficial for Chennai and Patiala; anthropogenic emission control would work for Chandani chowk, Goa and Patiala; emission control of CO is required for Mahabaleshwar and Thiruvanathapuram. Under low VOC/NOx ratio conditions, O3 varies with the ratio, NO/NO2, with a negative (positive) slope indicating VOC-sensitive (NOx-sensitive) regime. Peak O3 isopleths as a function of NOx and VOC depicting distinct patterns suggest that O3 variation is entirely non-linear for a given NOx or VOC.

NOX2 and NOX5 are increased in cardiac microvascular endothelium of deceased COVID-19 patients.

BACKGROUND: Cardiac injury and inflammation are common findings in COVID-19 patients. Autopsy studies have revealed cardiac microvascular endothelial damage and thrombosis in COVID-19 patients, indicative of microvascular dysfunction in which reactive oxygen species (ROS) may play a role. We explored whether the ROS producing proteins NOX2, NOX4 and NOX5 are involved in COVID-19-induced cardio-microvascular endothelial dysfunction. METHODS: Heart tissue were taken from the left (LV) and right (RV) ventricle of COVID-19 patients (n = 15) and the LV of controls (n = 14) at autopsy. The NOX2-, NOX4-, NOX5- and Nitrotyrosine (NT)-positive intramyocardial blood vessels fractions were quantitatively analyzed using immunohistochemistry. RESULTS: The LV NOX2+, NOX5+ and NT+ blood vessels fractions in COVID-19 patients were significantly higher than in controls. The fraction of NOX4+ blood vessels in COVID-19 patients was comparable with controls. In COVID-19 patients, the fractions of NOX2+, NOX5+ and NT+ vessels did not differ significantly between the LV and RV, and correlated positively between LV and RV in case of NOX5 (r = 0.710; p = 0.006). A negative correlation between NOX5 and NOX2 (r = -0.591; p = 0.029) and between NOX5 and disease time (r = -0.576; p = 0.034) was noted in the LV of COVID-19 patients. CONCLUSION: We show the induction of NOX2 and NOX5 in the cardiac microvascular endothelium in COVID-19 patients, which may contribute to the previously observed cardio-microvascular dysfunction in COVID-19 patients. The exact roles of these NOXes in pathogenesis of COVID-19 however remain to be elucidated.

Inferred vehicular emissions at a near-road site: Impacts of COVID-19 restrictions, traffic patterns, and ambient air temperature.

Vehicles are a major source of anthropogenic emissions of carbon monoxide (CO), nitrogen oxides (NOx), and black carbon (BC). CO and NOx are known to be harmful to human health and contribute to ozone formation, while BC absorbs solar radiation that contributes to global warming and also has negative impacts on human health and visibility. Travel restrictions implemented during the COVID-19 pandemic provide researchers the opportunity to study the impact of large, on-road traffic reductions on local air quality. Traffic counts collected along Interstate-95, a major eight-lane highway in Maryland (US), reveal a 60% decrease in passenger car totals and an 8.6% (combination-unit) and 21% (single-unit) decrease in truck traffic counts in April 2020 relative to prior Aprils. The decrease in total on-road vehicles led to the near-elimination in stop-and-go traffic and a 14% increase in the mean vehicle speed during April 2020. Ambient near-road (NR) BC, CO, NOx, and carbon dioxide (CO2) measurements were used to determine vehicular emission ratios (ΔBC/ΔCO, ΔBC/ΔCO2, ΔNOx/ΔCO, ΔNOx/ΔCO2, and ΔCO/ΔCO2), with each ratio defined as the slope value of a linear regression performed on the concentrations of two pollutants within an hour. A decrease of up to a factor of two in ΔBC/ΔCO, ΔBC/ΔCO2, ΔNOx/ΔCO2, and in the fraction of on-road diesel vehicles from weekdays to weekends shows diesel vehicles to be the dominant source of BC and NOx emissions at this NR site. We estimate up to a 70% reduction in BC emissions in April 2020 compared to earlier years, and attribute much of this to lower diesel BC emissions resulting from improvements in traffic flow and fewer instances of acceleration and braking. Future efforts to reduce vehicular BC emissions should focus on improving traffic flow or turbocharger lag within diesel engines. Inferred BC emissions from the NR site also depend on ambient temperature, with an increase of 54% in ΔBC/ΔCO from -5 to 20 °C during the cold season, similar to previous studies that reported increasing BC emissions with rising temperature. The default setting of MOVES3, the current version of the mobile emission model used by the US EPA, does not adjust hot-running BC emissions for ambient temperature. Future work will focus on improving the accuracy of mobile emissions in air quality modeling by incorporating the effects of temperature and traffic flow in the system used to generate mobile emissions input for commonly used air quality models.

Attributing Increases in Ozone to Accelerated Oxidation of Volatile Organic Compounds at Reduced Nitrogen Oxides Concentrations.

Surface ozone (O3) is an important secondary pollutant affecting climate change and air quality in the atmosphere. Observations during the COVID-19 lockdown in urban China show that the co-abatement of nitrogen oxides (NOx) and volatile organic compounds (VOCs) caused winter ground-level O3 increases, but the chemical mechanisms involved are unclear. Here we report field observations in the Shanghai lockdown that reveals increasing photochemical formation of O3 from VOC oxidation with decreasing NOx. Analyses of the VOC profiles and NO/NO2 indicate that the O3 increases by the NOx reduction counteracted the O3 decreases through the VOC emission reduction in the VOC-limited region, and this may have been the main mechanism for this net O3 increase. The mechanism may have involved accelerated OH-HO2-RO2 radical cycling. The NOx reductions for increasing O3 production could explain why O3 increased from 2014 to 2020 in response to NOx emission reduction even as VOC emissions have essentially remained unchanged. Model simulations suggest that aggressive VOC abatement, particularly for alkenes and aromatics, should help reverse the long-term O3 increase under current NOx abatement conditions.

QUANTIFYING THE IMPACT OF COVID-19 RESTRICTIONS ON EMISSIONS USING INVERSE MODELLING AND MEASUREMENTS

An inversion system that uses a Bayesian approach to combine measurements and ADMS-Urban modelled data by adjusting individual source emissions, subject to estimated uncertainty in the measurements and emissions, has previously been applied to optimising road traffic emissions in Cambridge. In this study the system has been applied specifically to the impact of interventions, in particular the impact of COVID-19 lockdowns on NOX emissions from road traffic and other sources in London. The ADMS-Urban model was used to calculate a priori hourly NOX concentrations at 195 receptors in London representing 115 reference monitors and 80 Breathe London Network AQMesh sensors. Input data included hourly meteorological measurements from Heathrow Airport, hourly NOX concentrations from 4 rural background monitoring sites and buildings road centreline data from Ordnance Survey. A priori emissions were obtained from the London Atmospheric Emissions Inventory (LAEI) for 35 point sources, approximately 70,000 major road sources and 2,500 1km grid cells representing minor road, heating and other sources. The analysis period was 1 January 2020 to 30 April 2021. Estimated uncertainties of 4 and 12 µg/m3 were applied to reference and sensor measurements respectively, while emissions uncertainties of 100%, 50%, 20% were applied to road traffic, fuels and other emissions respectively. Road traffic emissions were assumed to have error covariance of 40% of their emissions uncertainty. Measured NOX concentrations in London reduced significantly during lockdown, with the greatest reduction (around 60%) at kerbside and roadside sites in Central London. However, poor dispersal conditions led to increased concentrations at times when restrictions were tightest. In contrast, inversion system results demonstrate that NOX emissions from road traffic dropped by around 60% in London compared with pre-lockdown levels and that this reduction occurred when the strictest lockdown measures were in force. The results also show that NOX road traffic emissions were still approximately 30% lower than pre-lockdown levels at the end of April 2021. This analysis demonstrates that lower cost sensors such as AQMesh can provide valuable insight into the effects of policy measures (in this case lockdown restrictions), if their increased uncertainty compared with reference monitors is accounted for. © British Crown Copyright (2022)

Cyclophilin D-mediated angiotensin II-induced NADPH oxidase 4 activation in endothelial mitochondrial dysfunction that can be rescued by gallic acid.

Vascular endothelial dysfunction plays a central role in the most dreadful human diseases, including stroke, tumor metastasis, and the coronavirus disease 2019 (COVID-19). Strong evidence suggests that angiotensin II (Ang II)-induced mitochondrial dysfunction is essential for endothelial dysfunction pathogenesis. However, the precise molecular mechanisms remain obscure. Here, polymerase-interacting protein 2 (Poldip 2) was found in the endothelial mitochondrial matrix and no effects on Poldip 2 and NADPH oxidase 4 (NOX 4) expression treated by Ang II. Interestingly, we first found that Ang II-induced NOX 4 binds with Poldip 2 was dependent on cyclophilin D (CypD). CypD knockdown (KD) significantly inhibited the binding of NOX 4 to Poldip 2, and mitochondrial ROS generation in human umbilical vein endothelial cells (HUVECs). Similar results were also found in cyclosporin A (CsA) treated HUVECs. Our previous study suggested a crosstalk between extracellular regulated protein kinase (ERK) phosphorylation and CypD expression, and gallic acid (GA) inhibited mitochondrial dysfunction in neurons depending on regulating the ERK-CypD axis. Here, we confirmed that GA inhibited Ang II-induced NOX 4 activation and mitochondrial dysfunction via ERK/CypD/NOX 4/Poldip 2 pathway, which provide novel mechanistic insight into CypD act as a key regulator of the NOX 4/Poldip 2 axis in Ang II-induced endothelial mitochondrial dysfunction and GA might be beneficial in the treatment of wide variety of diseases, such as COVID-19, which is worthy further research.

Impact of COVID-19 restrictive precautions on air quality: case of Zonguldak, Turkey

The purpose of this study was to investigate and assess how restrictive COVID-19 precautions affect air quality in Zonguldak, as well as to determine the relationship between air quality and meteorological variables under these conditions. Daily PM2.5, PM10, SO2, and NOx concentrations and meteorological data, from 1 March to 31 May 2018, 2019, and 2020 were collected for this research. During the 2020 restrictive COVID-19 precautions, it was determined that concentrations of air pollutants were different and low based on the 95% confidence interval by using paired t-test samples. Meteorological variables were found to be similar to previous years, and the correlation between them and air pollutants was found to be significant (P < 0.01) but low according to Pearson correlations. As a result, meteorological variables were determined to have no direct effect on the low concentrations of air quality emissions during the 2020 pandemic. The overall findings revealed that anthropogenic impact has a negative impact on air quality and the air quality had improved during the COVID pandemic. Furthermore, the restriction on the region's coalmines during the COVID-19 pandemic has significant impact on the improvement of air quality.

The effect of COVID-19 lockdown and meteorological parameters on air pollutants in Samsun, Turkey

In this study, to determine the effect of the lockdown applied in Samsun, Turkey, between 1 March to 31 May due to the COVID-19 pandemic, the concentration of air pollutants parameters (PM10, SO2, NO2 and O-3) were measured at the same time interval of before lockdown and during the lockdown were compared. In addition, the relationship between the concentration of air pollutants and meteorological parameters such as wind speed, temperature, relative humidity, dew point and pressure was analysed statistically. The lockdown caused the most significant reduction in the concentration of NO2, followed by SO2, O-3 and PM10. Unlike SO2 and NO2, PM10 was less affected by lockdown since it also has natural sources. Between the meteorological parameters interested, wind speed and temperature showed a strong correlation with the air pollutants due to their transportation and conversion effects, while relative humidity, dew point and pressure showed a very weak correlation.

Elucidating the impacts of COVID-19 lockdown on air quality and ozone chemical characteristics in India

India implemented a stay-at-home order (i.e. lockdown) on 24 March 2020 to decrease the spread of novel COVID-19, which reduced air pollutant emissions in different sectors. The Weather Research and Forecasting model with Chemistry (WRF-Chem) was used to better understand the processes controlling the changes in PM2.5 and ozone in northern India during the lockdown period, including (1) the contributions of inter-annual variability in meteorology and emissions (dust, biogenic, and biomass burning) and lockdown emissions to changes in PM2.5 and ozone in northern India and (2) to analyze changes in ozone production regimes due to the lockdown. We found that both meteorology and lockdown emissions contributed to daytime PM2.5 (-12% and -12%, respectively) and ozone (-8% and -5%, respectively) reduction averaged in April 2020 in the Indo-Gangetic Plain, and in smaller magnitudes in northern India. However, the ozone concentration response to reductions in its precursors (i.e. NO2 and VOCs) due to the lockdown emissions was not constant over the domain. While the ozone concentration decreased in most parts of the domain, it occasionally increased in major cities like Delhi and in regions with many power plants. We utilized the reaction rate information in WRF-Chem to study the ozone chemistry. We found carbon monoxide, formaldehyde, isoprene, acetaldehyde, and ethylene as the major VOCs that contribute to the ozone formation in India. We used the ratio of radical termination from radical-radical interactions to radical-NOx interactions, and its corresponding formaldehyde to NO2 ratio (FNR) to find the ozone chemical regimes. We showed that the FNR transition range in a region depends on whether it is an urban, rural, or power plant region. Using the FNR information, we found that most parts of India are within the NOx-limited regime. We also found that large emission reduction during the lockdown period shifted the chemical regimes toward NOx-limited although it did not necessarily change the chemical regime in many VOC-limited regions. The results of this study highlight the fact that reducing the exposure to both PM2.5 and ozone requires air pollution management strategies that consider both NOx and VOC emission reductions, and that take into account regional characteristics.

Disentangling the Impact of the COVID-19 Lockdowns on Urban NO2 From Natural Variability.

TROPOMI satellite data show substantial drops in nitrogen dioxide (NO2) during COVID-19 physical distancing. To attribute NO2 changes to NO x emissions changes over short timescales, one must account for meteorology. We find that meteorological patterns were especially favorable for low NO2 in much of the United States in spring 2020, complicating comparisons with spring 2019. Meteorological variations between years can cause column NO2 differences of ~15% over monthly timescales. After accounting for solar angle and meteorological considerations, we calculate that NO2 drops ranged between 9.2% and 43.4% among 20 cities in North America, with a median of 21.6%. Of the studied cities, largest NO2 drops (>30%) were in San Jose, Los Angeles, and Toronto, and smallest drops (<12%) were in Miami, Minneapolis, and Dallas. These normalized NO2 changes can be used to highlight locations with greater activity changes and better understand the sources contributing to adverse air quality in each city.

Global Civil Aviation Emissions Estimates for 2017–2020 Using ADS-B Data

Aviation is a growing source of atmospheric emissions impacting the Earth's climate and air quality. Comprehensive assessments of the environmental impact of this industry require up-to-date, spatially resolved, and speciated emissions inventories. We develop and evaluate the first such estimate of global emissions from aircraft operations for the years 2017-2020. Aircraft activity data, based on flights registered by networks of aircraft Automatic Dependent Surveillance-Broadcast (ADS-B) telemetry receivers, are used together with the Base of Aircraft Data (BADA) 3.15 aircraft performance model and the International Civil Aviation Organization Engine Emissions Databank to estimate spatially resolved fuel burn and emissions of CO2, H2O, NOx (NO+NO2), SOx (SO2+SO42-), CO, unburnt hydrocarbons (HC), and nonvolatile particulate matter (nvPM). We calculate that 937 Tg of CO2 and 4.62 Tg of NOx were emitted by aircraft in 2019, and quantify the evolution of the fleet average emission indices over time. Owing to impacts from COVID-19, we estimate a 48% lower fuel burn, resulting in 463 Tg less CO2 and 2.29 Tg less NOx emitted in 2020 than what would be otherwise expected. We conclude that ADS-B is a viable source of data to generate global emissions estimates in a timely and transparent manner for monitoring and assessing aviation's atmospheric impacts.

Haze caused by NOx oxidation under restricted residential and industrial activities in a mega city in the south of North China Plain.

The formation of secondary aerosol species, including nitrate and sulfate, induces severe haze in the North China Plain. However, despite substantial reductions in anthropogenic pollutants due to severe restriction of residential and industrial activities in 2020 to stop the spread of COVID-19, haze still formed in Zhengzhou. We compared ionic compositions of PM2.5 during the period of the restriction with that immediately before the restriction and in the comparison period in 2019 to investigate the processes that caused the haze. The average concentration of PM2.5 was 83.9 µg m-3 in the restriction period, 241.8 µg m-3 before the restriction, and 94.0 µg m-3 in 2019. Nitrate was the largest contributor to the PM2.5 in all periods, with an average mass fraction of 24%-30%. The average molar concentration of total nitrogen compounds (NOx + nitrate) was 0.89 µmol m-3 in the restriction period, which was much lower than that in the non-restriction periods (1.85-2.74 µmol m-3). In contrast, the concentration of sulfur compounds (SO2 + sulfate) was 0.34-0.39 µmol m-3 in all periods. The conversion rate of NOx to nitrate (NOR) was 0.35 in the restriction period, significantly higher than that before the restriction (0.26) and in 2019 (0.25). NOR was higher with relative humidity in 40-80% in the restriction period than in the other two periods, whereas the conversion rate of SO2 to sulfate did not, indicating nitrate formation was more efficient during the restriction. When O3 occupied more than half of the oxidants (Ox = O3 + NO2), NOR increased rapidly with the ratio of O3 to Ox and was much higher in the daytime than nighttime. Therefore, haze in the restriction period was caused by increased NOx-to-nitrate conversion driven by photochemical reactions.

Health effects and known pathology associated with the use of E-cigarettes.

In recent years, new nicotine delivery methods have emerged, and many users are choosing electronic cigarettes (e-cigarettes) over traditional tobacco cigarettes. E-cigarette use is very popular among adolescents, with more than 3.5 million currently using these products in the US. Despite the increased prevalence of e-cigarette use, there is limited knowledge regarding the health impact of e-cigarettes on the general population. Based on published findings by others, E-cigarette is associated with lung injury outbreak, which increased health and safety concerns related to consuming this product. Different components of e-cigarettes, including food-safe liquid solvents and flavorings, can cause health issues related to pneumonia, pulmonary injury, and bronchiolitis. In addition, e-cigarettes contain alarmingly high levels of carcinogens and toxicants that may have long-lasting effects on other organ systems, including the development of neurological manifestations, lung cancer, cardiovascular disorders, and tooth decay. Despite the well- documented potential for harm, e-cigarettes do not appear to increase susceptibility to SARS-CoV- 2 infection. Furthermore, some studies have found that e-cigarette users experience improvements in lung health and minimal adverse effects. Therefore, more studies are needed to provide a definitive conclusion on the long-term safety of e-cigarettes. The purpose of this review is to inform the readers about the possible health-risks associated with the use of e-cigarettes, especially among the group of young and young-adults, from a molecular biology point of view.

Effect of Different Combustion Modes on the Performance of Hydrogen Internal Combustion Engines under Low Load

Detailed hydrogen–air chemical reaction mechanisms were coupled with the three-dimensional grids of an experimental hydrogen internal combustion engine (HICE) to establish a computational fluid dynamics (CFD) combustion model based on the CONVN1 -https://media.proquest.com/media/hms/PFT/1/iyX6N?_a=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%3D%3D&_s=XxDsfbWeNCPMojxxWroCr%2FH0Al4%3D ERGE software. The effects of different combustion modes on the combustion and emission characteristics of HICE under low load were studied. The simulation results showed that, with the increase in excess hydrogen, the equivalent combustion and excessive hydrogen combustion modes with medium-cooled exhaust gas recirculation (EGR) dilution could improve the intensity of the in-cylinder combustion of HICE, increase the peak values of pressure and temperature in the cylinder, and then improve the indicated thermal efficiency of HICE under low load. However, larger excessive hydrogen combustion could weaken the improvement in performance;therefore, the performance of HICE could be comprehensively improved by the adoption of excessive hydrogen combustion with a fuel–air ratio below 1.2 under low load. The obtained conclusions indicate the research disadvantages in the power and emission performances of HICE under low load, and they are of great significance for the performance optimization of HICE. Furthermore, a control strategy was proposed to improve the stability of HICE under low load.

Disengaging the COVID-19 Clutch as a Discerning Eye Over the Inflammatory Circuit During SARS-CoV-2 Infection.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) causes the cytokine release syndrome (CRS) and leads to multiorgan dysfunction. Mitochondrial dynamics are fundamental to protect against environmental insults, but they are highly susceptible to viral infections. Defective mitochondria are potential sources of reactive oxygen species (ROS). Infection with SARS-CoV-2 damages mitochondria, alters autophagy, reduces nitric oxide (NO), and increases both nicotinamide adenine dinucleotide phosphate oxidases (NOX) and ROS. Patients with coronavirus disease 2019 (COVID-19) exhibited activated toll-like receptors (TLRs) and the Nucleotide-binding and oligomerization domain (NOD-), leucine-rich repeat (LRR-), pyrin domain-containing protein 3 (NLRP3) inflammasome. The activation of TLRs and NLRP3 by SARS-CoV-2 induces interleukin 6 (IL-6), IL-1ß, IL-18, and lactate dehydrogenase (LDH). Herein, we outline the inflammatory circuit of COVID-19 and what occurs behind the scene, the interplay of NOX/ROS and their role in hypoxia and thrombosis, and the important role of ROS scavengers to reduce COVID-19-related inflammation.

Air Quality in Two Northern Greek Cities Revealed by Their Tropospheric NO2 Levels

In this article, we aim to show the capabilities, benefits, as well as restrictions, of three different air quality-related information sources, namely the Sentinel-5Precursor TROPOspheric Monitoring Instrument (TROPOMI) space-born observations, the Multi-Axis Differential Optical Absorption Spectroscopy (MAX-DOAS) ground-based measurements and the LOng Term Ozone Simulation-EURopean Operational Smog (LOTOS-EUROS) chemical transport modelling system simulations. The tropospheric NO2 concentrations between 2018 and 2021 are discussed as air quality indicators for the Greek cities of Thessaloniki and Ioannina. Each dataset was analysed in an autonomous manner and, without disregarding their differences, the common air quality picture that they provide is revealed. All three systems report a clear seasonal pattern, with high NO2 levels during wintertime and lower NO2 levels during summertime, reflecting the importance of photochemistry in the abatement of this air pollutant. The spatial patterns of the NO2 load, obtained by both space-born observations and model simulations, show the undeniable variability of the NO2 load within the urban agglomerations. Furthermore, a clear diurnal variability is clearly identified by the ground-based measurements, as well as a Sunday minimum NO2 load effect, alongside the rest of the sources of air quality information. Within their individual strengths and limitations, the space-borne observations, the ground-based measurements, and the chemical transport modelling simulations demonstrate unequivocally their ability to report on the air quality situation in urban locations.