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Nitrate ( NO 3 − ) has properties that can improve muscle function, leading to improvements in metabolic cost of exercise as well as enhance force production. Gymnastics is a whole-body sport, involving events that demand a high level of strength and fatigue resistance. However, the effect of NO 3 − supplementation on both upper- and lower-body function in gymnasts is unknown. This study examined the effect of acute beetroot juice (BRJ) supplementation on isokinetic strength and endurance of the upper- and lower-body in highly trained international-level male gymnasts. In a double-blind, randomized crossover design, 10 international-level male gymnasts completed two acute supplementation periods, consuming either 2 × 70 ml NO 3 − -rich (∼12.8 mmol/L of NO 3 − ) or NO 3 − -depleted (PLA) BRJ. Maximal strength of the upper-leg and upper-arm at 60°/s, 120°/s, 180°/s, and 300°/s, and muscular endurance (50 repeated isokinetic contractions at 180°/s) were assessed. Plasma NO 3 − (BRJ: 663 ± 164 μM, PLA: 89 ± 48 μM) and nitrite ( NO 2 − ) concentrations (BRJ: 410 ± 137 nmol/L, PLA: 125 ± 36 nmol/L) were elevated following BRJ compared to PLA (both p <.001). Maximal strength of knee and elbow extensors and flexors did not differ between supplements (p >.05 for all velocities). Similarly, fatigue index of knee and elbow extension and flexion was not different between supplements (all p >.05). Acute BRJ supplementation, containing ∼12.8 mmol/L of NO 3 − , increased plasma NO 3 − and NO 2 − concentrations, but did not enhance isokinetic strength or fatigue resistance of either upper or lower extremities in international-level male gymnasts. [ABSTRACT FROM AUTHOR]

Although the d-band center theory can well describe the interaction between gas molecules and transition metal surfaces, the detailed reaction process and specific adsorption conditions are unclear. Hence, in this work, we systematically studied the adsorption mechanism, adsorption conditions, and recovery time of NO and NO2 molecules on different transition metals (Cu, Ag, Au, Ni, Pd, Pt, Rh, Ru, Tc, Mo, Nb, and Zr) surfaces by first-principles. The results indicated that the charge transfers from the dz2, dxz, and dyz orbitals of substrate atoms to the HOMOs/LUMOs of NO and NO2. Moreover, we demonstrate that the interaction orbitals between the NO/NO2 and the metal atoms excellently correspond with the match of energy level and parity, and the maximum overlap of the orbital wave function. Interestingly, the excellent linear scaling between charge transfer and the d-band center, work function, and matrix element (V2ad) of metals has been confirmed. Specifically, the different recovery times of these systems at different temperatures were explored. Our results can provide a feasible way for exploring gas-sensitive materials in the experiments. [ABSTRACT FROM AUTHOR]

Hydrogen engines show great potential as a power source with good combustion performance, zero carbon emissions, and diverse sources. However, the exhaust emission characteristics with high water vapor (H 2 O) content have not yet been clarified. This study presents the exhaust emissions of a heavy-duty direct-injection hydrogen engine under various operational parameters, with a focus on the H 2 O content. The results reveal important exhaust emissions characteristics of the hydrogen engine, including lower exhaust temperature (200 °C–400 °C), higher unburned H 2 emissions (up to 17100 ppm), less nitrogen oxide (NO) generation (<1000 ppm), and higher H 2 O content (6%–40%). Additionally, unburned H 2 rises, and NO and H 2 O decrease as the excess air ratio (λ) increases. When λ is greater than 3, NO levels fall sharply to below 100 ppm. Optimal emissions performance is achieved with a 5 °CA BTDC ignition timing where low levels of H 2 , H 2 O, and NO are maintained. Increasing hydrogen injection pressure decreases H 2 but raises exhaust temperature, H 2 O, and NO emissions. Excessively delaying hydrogen injection timing adversely affects the concentration gradient in the cylinder, increasing unburned H 2 emissions. The best emissions performance is observed at a hydrogen injection timing of 110 °CA BTDC. • Studied the exhaust emissions of heavy-duty direct-injection hydrogen engine. • Clarified the high H 2 O and H 2 emission characteristics of hydrogen engines. • Analyzed lower NO emissions and exhaust temperature from hydrogen engines. • Explored the effects of operating conditions on emission characteristics. [ABSTRACT FROM AUTHOR]

A novel plasma reactor is being investigated for green NOx production, crucial for nitrate‐based fertilizer manufacturing. Various parameters, including air flow rates, gas ratios, ozone, and catalyst effects are explored for NO → NO2 conversion. NOx concentrations reach ~0.6 vol%, with a total production of ~9.7 gr/h and energy cost of ~3.0 mJ/mol, notably favorable for atmospheric gliding arc plasma. Selectivity (~75%) towards NO2 is achieved with ozone addition or catalytic treatment, pivotal for nitrate fertilizer and HNO3 production. [ABSTRACT FROM AUTHOR]

Comprehensive Air Quality Model with extensions (CAMx)–Decoupled Direct Method (DDM) simulations of first-order ozone (O 3) sensitivity to nitrogen oxides (NO x) and volatile organic compounds (VOCs) emissions were performed and combined with modelled P H 2 O 2 / P HN O 3 ratios to obtain a range of thresholds for determining O 3 -sensitivity regimes for different areas of China. Utilising the new threshold ranges for photochemical indicators, the method for determining O 3 formation in the Ozone Source Apportionment Technology (OSAT) module within CAMx was improved by a dynamically varied threshold of P H 2 O 2 / P HNO 3 ratio. The O 3 concentration contributions in the newly added transition regime were apportioned to NO x and VOCs emissions in proportion to the relationship between the P H 2 O 2 / P HNO 3 ratio and first-order O 3 sensitivity. The source contributions of O 3 concentrations from different emission sectors from June to September 2019 were compared using the original and improved CAMx-OSAT. The results showed that the O 3 concentration contributions changed significantly in the NO x -limited regime, with a maximum decrease of 21.89%, while the contributions increased by up to 7.57% in the VOC-limited regime, and were within 15 µg/m3 in the transition regime. The modified OSAT module enabled a more sophisticated attribution of O 3 to precursor emissions and may have far-reaching implications for informing O 3 pollution control policy. [ABSTRACT FROM AUTHOR]

It has been hypothesized that air pollution can increase an individual's susceptibility to COVID-19. Our study sought to investigate if short-term exposure to a high average level of Air Quality Index (AQI), ozone (O3), particulate matter (PM2.5, PM10), sulfur dioxide (SO2), carbon monoxide (CO), and nitrogen dioxide (NO2) are risk factors for death from COVID-19. We conducted an unmatched case-control study to compare the risk of mortality among reported COVID-19 cases within metropolitan statistical areas in Indiana from March 31, 2020, to December 31, 2020 (N = 53,459). Air pollution concentration data at the county level were retrieved from the U.S. Environmental Protection Agency. Pollutant concentrations for the 90 days before disease development were averaged. Data were analyzed using stepwise logistic regression accounting for median air temperature, race, ethnicity, and preexisting conditions as confounders. At the population level, individuals who were exposed to a greater average of PM2.5 in the 90 days before the development of COVID-19 had an increased risk of death: OR = 2.16, 95% confidence interval (CI) [1.12, 18.57]. Individuals with chronic lung disease had an increased risk of death in relation to PM10: OR = 2.72, 95% CI [1.15, 6.43]. Short-term exposure to particulate matter may serve as a risk factor for COVID-19 mortality. [ABSTRACT FROM AUTHOR]

Climate change is a global threat to the environment and human health. Two of the main greenhouse gases that cause the greenhouse effect and raise global temperatures are carbon dioxide and nitrogen oxides. In this review paper, we investigated the effects of carbon dioxide and nitrogen oxides on climate change and the effects of climate change on Afghanistan. We found that high concentrations of carbon dioxide, which is now CO2 levels, have increased by 50% than before the Industrial Revolution, contributing to a rise in global temperature and precipitation. At the same time, Nitrous oxide is an important greenhouse gas, with 310-fold higher potential for global warming than CO2 and leads to the depletion of stratospheric Ozone and other Nitrogen oxides, has a significant impact on plant health, including effects on chlorophyll levels, oxidative stress, and antioxidant responses. Afghanistan's climate change is predicted to increase the country's prevalence of illnesses linked to dust storms and poor air quality, especially in Kabul, the nation's capital. In addition, air pollution in Kabul is also likely to increase as a result of climate change. The alarming impacts of air pollution, with more than 3,000 deaths attributed to air pollution annually. Additionally, at least 700,000 individuals in Kabul have experienced various respiratory diseases. Due to climate change, Afghanistan's total glacier area has shrunk by 13.8%. In 2023, Afghanistan experienced early snow melt and below-average precipitation, causing second-season and irrigated crops to have less access to water. Reducing emissions and coping with the changing climate are essential steps towards tackling the complex issues these gases present and their wider effects on the environment and human health. [ABSTRACT FROM AUTHOR]

Secondary air pollution, especially ozone (O3) and secondary aerosols, are emerging air quality challenges confronting China. Nitrous acid (HONO), as the predominant source of hydroxyl radicals (OH), are acknowledged to be essential for secondary pollution. However, HONO concentrations are usually underestimated by current air quality models due to the inadequate representations of its sources. In the present study, we revised the Weather Research and Forecasting & Chemistry (WRF‐Chem) model by incorporating additional HONO sources, including primary emissions, photo‐/dark oxidation of NOx, heterogeneous uptake of NO2 on surfaces, and nitrate photolysis. By combining in‐situ measurements in the Yangtze River Delta (YRD) region, we found the improved model show much better performance on HONO simulation and is capable of reproducing observed high concentrations. The source‐oriented method is employed to quantitatively understand the relative importance of various processes, which showed that heterogeneous NO2 uptake on the ground surface was the major contributor to HONO formation in urban areas. Comparatively, photo‐oxidation of NOx is a main contributor in rural areas. The introduction of multiple sources of HONO led to an apparent increase in OH and hydroperoxyl (HO2) radicals. The promoted HO2 levels further increased diurnal O3 concentration by 4.5–12.9 ppb, while secondary inorganic and organic concentrations were also increased by 14%–32% during a typical secondary pollution event. The improved description of HONO emission and formation in the model substantially narrowed the gaps between simulations and observations, highlighting the great importance in understanding and numerical representations of HONO in secondary pollution study. Plain Language Summary: Nitrous acid (HONO) has a vigorous potential to produce hydroxyl radicals, contributing to tropospheric oxidation reactions. However, current air quality models lack detailed representation of HONO‐related processes. We revised a widely‐used air quality model based on recently reported mechanisms. The improved model can reasonably simulate actual HONO concentrations measured in the Yangtze River Delta region, one of the most urbanized city clusters in China. It is identified that the heterogeneous conversion of nitrogen dioxide on the ground surface and photo‐oxidation of nitrogen oxide may play an important role in HONO formation. The modeling result is indicative of the pronounced enhancement of HONO on secondary air pollutants, including ozone and secondary aerosols. This study highlights the critical impact of HONO on deteriorating secondary air pollution in city clusters. Key Points: Incorporating missing sources of HONO in the air quality model helps to better represent the observed magnitude and temporal variations of HONOHeterogeneous uptake of NO2 on the ground surface and photo‐oxidation of NOx are major contributors to HONO formationHONO can significantly deteriorate ozone and secondary aerosol pollution by enhancing atmospheric oxidizing capacity [ABSTRACT FROM AUTHOR]

This study addresses the ongoing demand for increased efficiency and reduced emissions in turbomachinery combustion systems. A custom-built high-pressure combustor was designed and manufactured at the Low Carbon Combustion Centre (LCCC) of the University of Sheffield to investigate the impact of different aromatic hydrocarbons on emission rates. The research involved the comprehensive testing of Jet−A1 fuel and six aromatic species blends under high-pressure conditions of 10 bar. Based on the numerical CFD simulations by ANSYS 19.2, tangential dual air injection and a strategically placed V-shaped baffle plate were utilised to enhance fuel-air mixing and combustion stability. Experimental results demonstrated a negative correlation between combustion temperature and particulate matter (PM) emissions, with higher temperatures yielding lower PM emissions. Unburned hydrocarbons (UHCs), nitrogen oxides ( N O x ), carbon monoxide ( C O ), and carbon dioxide ( C O 2 ) emissions were also analysed. Ethylbenzene produced the highest UHC and C O emissions, while Indane exhibited the lowest levels of these pollutants, suggesting more complete combustion. O−xylene generated the highest N O x emissions, correlating with its higher combustion temperatures. This research enhances our understanding of gas turbine combustor design and the combustion behaviour of aromatic species, providing valuable insights for developing low-emission, high-efficiency gas turbine combustion technologies. [ABSTRACT FROM AUTHOR]

This paper focuses on the combustion of hydrogen in boilers, as it appears to be a more effective method than using fuel cells for heating purposes due to higher boiler efficiency. One of the main disadvantages of hydrogen combustion in air is NO x formation. Therefore, the authors decided to introduce corona discharge as an innovative technique to clean hydrogen flue gas by effectively reducing NO x levels. The method involves generating positive plasma at atmospheric pressure by applying up to a 23 kV voltage difference between rod and ring-shaped electrodes. Experimental studies have shown that corona discharge can significantly lower the concentrations of NO and NO x in exhaust gases. The maximum DeNO x level was found to be 32.3%, while the plasma generator uses 17.5% of the power contained in burned hydrogen. The findings suggest that this technology holds potential for application in industrial hydrogen combustion systems, offering an environmentally friendly alternative to conventional NO x reduction methods. [Display omitted] • Corona discharge is promising approach for cleaning hydrogen flue gas from NO x. • The level of NO x removal depends on their concentration. • After plasma treatment, the level of NO decreases while NO 2 increases. • The maximum investigated level of DeNO x was 32.3%. [ABSTRACT FROM AUTHOR]

Ammonia (NH 3) and biomass are recognised as renewable energy carriers with substantial promise for reducing carbon emissions. However, the issue of nitrogen oxides (NO X , including NO and NO 2) and nitrous oxide (N 2 O) emissions from ammonia combustion and soot from biomass combustion, remains a pressing concern due to their detrimental impacts on the environment and human health. This study investigated the mechanism of pollutant formation during ammonia-lignin co-firing through reactive molecular dynamics (RMD) simulations. The results indicate that co-firing a certain amount of ammonia with lignin can reduce the formation of soot. This is mainly due to NH 2 radicals converting a portion of polycyclic aromatic hydrocarbon (PAH) precursors into C–N compounds. However, it is necessary to maintain higher ammonia concentrations. Adding a small quantity of ammonia would decrease the extent of oxidative reactions within the system and fail to generate enough NH 2 radicals to consume the carbon atoms forming PAH precursors, ultimately resulting in increased soot production. The impact of lignin on the formation of NO X and N 2 O during ammonia combustion has two main aspects: Firstly, the oxidising radicals formed during the initial decomposition of lignin promote the generation of N–O bonds, leading to an increase in the quantities of NO X and N 2 O during the initial reaction stage. Secondly, the carbon-containing products produced from lignin decomposition consume nitrogen atoms by forming N–C bonds, thereby diminishing available nitrogen atoms for nitrogen oxides formation. This study provides new insights into the formation of primary pollutants of ammonia and biomass co-firing on an atomic scale, which can help develop pollutant mitigation measures. • The chemical mechanism of pollutant formation during the co-firing of ammonia and biomass lignin is revealed. • A small quantity of ammonia promotes soot formation but increased quantities have the opposite effect. • NO production is enhanced by lignin in the initial stage of the co-firing, but the trend is reversed subsequently. • NO 2 formation is linked to oxidative reactions, while N 2 O formation depends on NH 2 concentration. [ABSTRACT FROM AUTHOR]

In a future energy system prospective, predictably dominated by (often) remote and (always) unsteady, nondispatchable renewable power generation from solar and wind resources, hydrogen (H2) and ammonia (NH3) have emerged as logistically convenient, chemically simple and carbon-free chemicals for energy transport and storage. Moreover, the reliability of supply of a specific fuel feedstock will remain unpredictable in the upcoming energy transition period. Therefore, the ability of gas turbine combustion systems to seamlessly switch between very disparate types of fuels must be ensured, aiming at intrinsically fuel-flexible combustion systems, i.e., capable of operating cleanly and efficiently with novel carbon-free energy vectors like H2 and NH3 as well as conventional fossil fuels, e.g., natural gas or fuel oils (back-up feedstock). In this context, a convenient feature of Ansaldo's constant pressure sequential combustion (CPSC) system, resulting in a fundamental advantage compared to alternative approaches, is the possibility of controlling the amount of fuel independently fed to the two combustion stages, depending on the fuel reactivity and combustion characteristics. The fuel-staging strategy implemented in the CPSC system, due to the intrinsic characteristics of the auto-ignition stabilized reheat flame, has already been proven able of handling fuels with large hydrogen fractions without significant penalties in efficiency and emissions of pollutants. However, ammonia combustion is governed by widely different thermo-chemical processes compared to hydrogen, requiring a considerably different approach to mitigate crucial issues with extremely low flame reactivity (blow-out) and formation of significant amounts of undesired pollutants and greenhouse gases (NOx and NO2). In this work, we present a fuel-flexible operational concept for the CPSC system and, based on unsteady Reynolds-Averaged Navier-Stokes (uRANS) and large eddy simulation (LES) performed in conjunction with detailed chemical kinetics, we explore for the first time full-load operation of the CPSC architecture in a Rich-Quench-Lean (RQL) strategy applied to combustion of partially-decomposed ammonia. Results from the numerical simulations confirm the main features of ammonia-firing in RQL operation already observed from previous work on different combustion systems and suggests that the CPSC architecture has excellent potential to operate in RQL-mode with low NOx and NO2 emissions and good combustion efficiency. [ABSTRACT FROM AUTHOR]

Microgas turbines are an on-site power and heat generation technology with a small footprint, low gaseous (NOx) and acoustic emissions, low maintenance, and high-grade heat. They entered the market at the dawn of the twentieth century; nevertheless, they achieved minimal success and a marginal role in the microgeneration market. Reciprocating internal combustion engines (ICE) raised considerable barriers hindering their market deployment, and fuel cells are also set to compete in this segment. In this scenario, this work presents an analysis of competitiveness grounded in the theory of constraints (TOC). To this end, a specific key performance indicator (KPI) has been produced, which combines technical, economic, and operational factors according to the end-user requirement. This indicator is a function of several penalty factors representing technology and market barriers, which aims to yield a unique insight into the most competitive technology for a given application, accounting for the uncertainty deriving from technical and economic elements. This novel methodology is applied to a new potential niche market: Power-to-Hydrogen-to-Power for remote applications. The methodology is applied to an independent rural community in South Wales for which a backup power system is assessed. Four technologies are considered in the analysis: reciprocating engines, fuel cells, and two different microturbines layouts. Finally, this work provides an overview of the possible R&D&I paths necessary to increase the competitiveness of microgas turbines in certain markets. [ABSTRACT FROM AUTHOR]

The reduction of nitrogen oxides (NOx), critical pollutants from stationary to mobile sources, mainly relies on the selective catalytic reduction (NH3-SCR) method, employing ammonia to reduce NOx into nitrogen and water. However, conventional catalysts, while effective, pose both environmental and operational challenges. This study investigates ceria-zirconia-supported molybdenum-based catalysts, exploring the effects of zirconium doping and different catalyst synthesis techniques, i.e., co-precipitation and impregnation. The catalytic performance of the differently prepared samples was significantly influenced by the molybdenum incorporation method and the zirconium content within the ceria-zirconia support. Co-precipitation at higher temperatures resulted in catalysts with better structural attributes but slightly lower catalytic activity compared to those prepared via impregnation. Optimal NOx reduction (close to 100%) was observed at a 15 mol% zirconium doping level when using the impregnation method. [ABSTRACT FROM AUTHOR]

Homogeneous charge-induced ignition (HCII), which uses trace diesel to induce the ignition of gasoline pre-mixture, is characterized by rapid lean combustion and is generally regarded as efficient, clean and controllable. In this paper, a conventional diesel engine has been modified to run all cylinders in HCII mode and the influence of diesel injection pressure (DIP) on overall engine performance was experimentally studied. Results show that the increase of DIP can expand the ignition area of gasoline and enlarge the premixed combustion ratio of diesel, thus promoting rapid combustion and improving brake thermal efficiency. The increase of DIP is beneficial to the control of ignition time and combustion phase, thus reducing the cyclic fluctuation. The increase of DIP can effectively reduce the emission of total hydrocarbon, carbon monoxide and smoke, while the emission of nitrogen oxides (NOx) is insensitive to the change of DIP, so the trade-off relationship between NOx and smoke disappears. However, excessive DIP will still lead to increased combustion noise, and deteriorated combustion quality caused by too less inducing diesel, etc. The appropriate value is about 1000 bar within the test range. [ABSTRACT FROM AUTHOR]

In this study, the impacts of zinc oxide (ZnO) loading on the selective catalytic reduction (SCR) performance of the cerium oxide-molybdenum oxide (CeOx–MoO3) catalyst were systematically investigated. With the introduction of ZnO, the catalyst's nitrogen oxides (NOx) reduction activity presented a downward trend. At 300 °C, the NOx conversion efficiency of the sample with 4 wt% ZnO loaded dropped below 70%, ~ 22% lower than that of the fresh sample. This decrease was attributed to the neutralization of the catalysts' acid sites by the added ZnO, which inhibited the adsorption of ammonia as the reductant. Furthermore, the introduction of ZnO resulted in a decrease in the relative content of Ce3+, which interfered with the formation of oxygen vacancies and the activation of oxygen. This weakened oxidative ability slowed down the activation of the reactants. Even though the specific surface area of the CeOx–MoO3 catalyst was enhanced due to ZnO, this promotional effect was insufficient to completely overcome the aforementioned negative impacts. Consequently, the efficiency of the NOx elimination process over the ZnO-loaded catalysts was adversely affected. Despite the addition of ZnO, the Eley–Rideal reaction pathway continued to dominate in the deNOx process. [ABSTRACT FROM AUTHOR]

Heavy-duty diesel vehicles are a significant source of nitrogen oxides (NOx) in the atmosphere. The Selective Catalytic Reduction (SCR) system is a primary aftertreatment device for reducing NOx emissions from heavy-duty diesel vehicles. With increasingly stringent NOx emission regulations for heavy-duty vehicles in major countries, there is a growing focus on reducing NOx emissions under low exhaust temperature conditions, as well as monitoring the conversion efficiency of the SCR system over its entire lifecycle. By reviewing relevant literature mainly from the past five years, this paper reviews the development trends and related research results of SCR technology, focusing on two main aspects: low-temperature NOx reduction technology and the combination of SCR systems with remote On-Board Diagnostics (OBD). Regarding low-temperature NOx reduction technology, the results of the review indicate that the combination of multiple catalytic shows potential for achieving high conversion efficiency across a wide temperature range; advanced SCR system arrangement can accelerate the increase in exhaust temperature within the SCR system; solid ammonium and gaseous reductants can effectively address the issue of urea not being able to be injected under low-temperature exhaust conditions. As for the combination of SCR systems with remote OBD, remote OBD can accurately assess NOx emissions from heavy-duty vehicles, but it needs algorithms to correct data and match the emission testing process required by regulations. Remote OBD systems are crucial for detecting SCR tampering, but algorithms must be developed to balance accuracy with computational efficiency. This review provides updated information on the current research status and development directions in SCR technologies, offering valuable insights for future research into advanced SCR systems. [ABSTRACT FROM AUTHOR]

Surface ozone (O3) and nitrogen oxides (NOx = NO + NO2) measured at the rural station in Belsk (51.83° N, 20.79° E), Poland, over the period of 1995–2023, were examined for long-term variability of O3 and its relationship to changes in the air temperature and NOx. Negative and positive trends were found for the 95th and 5th percentile, respectively, in the O3 data. A weak positive correlation (statistically significant) of 0.33 was calculated between O3 and the temperature averaged from sunrise to sunset during the photoactive part of the year (April–September). Recently, O3 maxima have become less sensitive to temperature changes, reducing the incidence of photochemical smog. The ozone–climate penalty factor decreased from 4.4 µg/m3/°C in the 1995–2004 period to 3.9 µg/m3/°C in the 2015–2023 period. The relationship between Ox (O3 + NO2) and NOx concentrations averaged from sunrise to sunset determined the local and regional contribution to Ox variability. The seasonal local and regional contributions remained unchanged in the period of 1995–2023, stabilizing the average O3 level at Belsk. "NOx-limited" and "VOC-limited" photochemical regimes prevailed in the summer and autumn, respectively. For many winter and spring seasons between 1995 and 2023, the type of photochemical regime could not be accurately determined, making it difficult to build an effective O3 mitigation policy. [ABSTRACT FROM AUTHOR]

Ammonia is one of the precursor gases in the formation of particulate matter (PM) that reacts with nitrogen oxides and sulfur oxides in the atmosphere. Based on the Clean Air Policy Support System (CAPSS) of Korea, the annual ammonia emissions amounted to 261,207 tons in 2020 and the agricultural source (manure management sector) contributes the highest proportion of the ammonia inventory. However, the methodology for the study of ammonia emissions in Korea has some limitations regarding the representativeness of the sites selected and the reliability of the measurement method. In this study, we aimed to recalculate the ammonia emissions from the livestock industry in Korea using the UK's estimation method, which uses the life cycle assessment of livestock manure. Three major animal types, i.e., cattle (beef cattle and dairy cows), pigs and chickens, and three major processes based on the manure flow, i.e., housing, manure storage and treatment and land application processes, were considered. The total ammonia emissions were estimated to be approximately 33% higher than the official ammonia emissions stated by the CAPSS. For the manure flow, the ammonia emissions were the highest from land application processes. The ammonia emissions from dairy cow and poultry manure were much higher than those stated by the CAPSS, while the emissions from beef cattle and pig manure showed similar levels. The methodology used in this study can offer an alternative approach to the ammonia emission estimation of the manure management sector in the agriculture industry of Korea. Korean emission factors based on the manure flow should be developed and applied in the future. [ABSTRACT FROM AUTHOR]

Nitrogen oxides (NOx) should be purified according to environmental regulations, being restricted increasingly year by year. A wide variety of denitration technologies, such as selective catalytic reduction (SCR) of NOx to nitrogen (N2) and NOx storage reduction (NSR) to N2 by injecting reducing agents like ammonia (NH3), has so far been developed practically. Sophisticated catalytic approaches are perhaps mandatory for the sustainability in energy including complete purification of NOx. As one of the solutions to overcome problems for environment and resource simultaneously, this concept article focuses on the utilization of reactive nitrogen (Nr) compounds, mainly NOx, for encouraging an opening to consider nitrogen circular economy. For the recycling of NOx via NH3, a challenging but rational catalytic technology can be proposed by an alternate switching the inlet gas between NOx containing oxidative gas and H2 containing reductive one without an operation to change the reaction temperature. Considering the reactivity of NOx higher than that of N2, this kind of NOx to NH3 (NTA) process is promising for synthesizing NH3, being valuable not only as fertilizer but also as fuel in near future. [ABSTRACT FROM AUTHOR]

Titanium tetrachloride (TiCl4) is a well-known source of titanium (Ti) for the formation of titanium nitride (TiN) barrier material in the semiconductor interconnection process; however, the reaction of by-products with airborne molecules can cause unexpected pump trips and equipment breakdown from the by-product powder build-up. Plasma scrubbers are used to decompose by-products, but hydrogen chloride (HCl) and nitrogen oxides are produced during and after the process. The process mechanisms change when the temperature and applied power of the heat source change. In this paper, we study the influence of the reactor temperature and applied power to the heat source on the decomposition capacity of TiCl4 in a plasma pretreatment system (PPS). We examine the effect of the temperature and heat source power to understand the reaction mechanisms for the composition and decomposition of gaseous species with chemical reactions through simultaneous methods. We analyzed the system with computational fluid dynamics (CFD) and chemical kinetic simulation to investigate the changes of the system mechanism. Subsequently, we achieved results for the correlation between the temperature of the reactor, power applied to the heat source, composition and decomposition of species, and chemical reaction mechanisms. [ABSTRACT FROM AUTHOR]

Atmospheric pressure plasmas are widely used for nitrogen fixation processes to produce ammonia NH3 or nitrogen oxides NOx, including, for example, nitrite NO2− or nitrate NO3−. Small‐scale atmospheric pressure plasma jets (APPJs) can provide the production of these species on demand at the site of consumption. The species of interest are generated by the plasma and can be dissolved in liquids, for example, to use them. In this work, liquid treatments were performed by an APPJ operated in a He–H2O ${{\rm{H}}}_{2}{\rm{O}}$–N2 ${{\rm{N}}}_{2}$–O2 ${{\rm{O}}}_{2}$ gas composition to investigate the influence of the gas composition on the production of hydrogen peroxide H2O2 ${{\rm{H}}}_{2}{{\rm{O}}}_{2}$, NH3 ${\text{NH}}_{3}$ and NO2‐ ${\text{NO}}_{2}^{ \mbox{-} }$. A validation of two H2O2 ${{\rm{H}}}_{2}{{\rm{O}}}_{2}$ diagnostics showed that the spectrophotometric approach using ammonium metavanadate was interfered by other species when N2 ${{\rm{N}}}_{2}$ was added to the system. Thus, electrochemical sensing of H2O2 ${{\rm{H}}}_{2}{{\rm{O}}}_{2}$ was performed. The concentrations of NH3 ${\text{NH}}_{3}$ and NO2‐ ${\text{NO}}_{2}^{ \mbox{-} }$ were measured by commercially available test kits based on the o‐phythalaldehyde method and the Griess reagent, respectively. At low N2 ${{\rm{N}}}_{2}$ admixtures, the dominant species was H2O2 ${{\rm{H}}}_{2}{{\rm{O}}}_{2}$ with a maximum concentration of 0.9 mM, while NO2− ${\text{NO}}_{2}^{-}$ became dominant at N2 ${{\rm{N}}}_{2}$ admixtures of 0.5% and higher with concentrations of up to 1.5 mM. NH3 ${\text{NH}}_{3}$ was also present in the system and could be measured at low concentrations of less than 0.2 mM in the liquid. By varying the treatment distance and the gas flow rate, insights into the transport phenomena of the species and their dissolution into the liquid could be gained. Low‐frequency pulsing of the radio frequency (RF) jet led to an accumulating effect on H2O2 ${{\rm{H}}}_{2}{{\rm{O}}}_{2}$, a reduced production of NO2− ${\text{NO}}_{2}^{-}$ and a switch from NOx ${\text{NO}}_{x}$‐dominated production to H2O2 ${{\rm{H}}}_{2}{{\rm{O}}}_{2}$‐dominated production. [ABSTRACT FROM AUTHOR]

The utilization of microalgae to treat carbon dioxide (CO2)-rich industrial off-gas has been suggested as both beneficial for emissions reduction and economically favorable for the production of microalgal products. Common sources of off-gases include coal combustion (2–15% CO2), cement production (8–15% CO2), coke production (18–23% CO2), and ore smelting (6–7% CO2). However, industrial off-gas also commonly contains other acid gas components [typically nitrogen oxides (NOX) and sulfur dioxide (SO2)] and metals that could inhibit microalgae growth and productivity. To utilize industrial off-gas effectively in microalgae cultivation systems, a number of solutions have been proposed to overcome potential inhibitions. These include bioprospecting to identify suitable strains, genetic modification to improve specific cellular characteristics, chemical additions, and bioreactor designs and operating procedures. In this review, results from microalgae experiments related to utilizing off-gas are presented, and the outcomes of different conditions discussed along with potential solutions to resolve limitations associated with the application of off-gas. [ABSTRACT FROM AUTHOR]

This article presents the results of engine and laboratory tests with fuel before and after treatment with a heavy particle generator. The results of the research have shown that in the course of conducted research the impact of heavy particle generator on fuel during engine tests leads to an increase in its detonation resistance and a reduction in fuel consumption (up to 15%), as well as significantly improves the environmental performance of the engine. The reduction in concentration of carbon monoxide (CO) from 0.09% to 0.03%, carbon dioxide - by 6% and nitrogen oxides - by 7%. The results of research of hydrocarbon composition of fuels by GC-MS method have shown that the impact of heavy particles generator have a favorable effect on the octane number of gasoline, as well as low-temperature properties of diesel fuel. The change of engine operation parameters after the impact of heavy particles generator is established. The change can occur as a result of complex influence on fuel and engine systems, and as a result of influence on a single factor, which is the root cause of the subsequent change of parameters. [ABSTRACT FROM AUTHOR]

The computational studies carried out previously taking as an example the BKZ-210-140 boiler installed at Tomsk-2 state-owned district power plant (SDPP) have shown that, given the existing scatter in the characteristics of coals fired at the power plant, the temperature of gases at the boiler furnace outlet may vary in a wide range (more than 100°С). Such variability of the operational parameters entails a number of problems, including difficulties with keeping a stable superheated steam temperature, increased risk of heating surfaces becoming slagged, and less efficient fuel combustion. A conclusion has been drawn based on the obtained computation results that the possibility of adjusting the flame's initial section vector by ±15° will make it possible to solve the above-mentioned problems to a significant extent. A tiltable burner is the key component of the combustion system with adjusting the flame position. Based on an analysis of the current operation conditions of the Tomsk-2 SDPP BKZ-210-140 boiler, technical solutions were developed on the design of a tiltable vortex burner intended for combusting pulverized coal as well as natural gas and fuel oil. The burner's outlet part is made so that it is possible to tilt it by ±15° in the vertical plane and by ±5° in the horizontal plane, which will make it possible to adjust the combustion mode in an efficient manner. The furnace process is simulated in the ANSYS Fluent software package under different boiler operation conditions. The simulation results show that, in the case of using the new burners, it is possible to improve the furnace process efficiency. By tilting the burner by ±15° in the vertical plane, it becomes possible to obtain the temperature adjustment range at the furnace outlet equal to 120°С. Based on the adopted technical solutions, design documentation for the burner has been developed. An experimental sample of the low-toxic tiltable vortex burner installed in the Tomsk-2 SDPP BKZ-210-140 boiler has been manufactured. [ABSTRACT FROM AUTHOR]

Concern about air-quality in urban areas has led to the implementation of Low Emission Zones as one of many other initiatives to control it. Recently in Spain, the enactment of a law made this mandatory for cities with a population larger than 50k inhabitants. The delimitation of these areas is not without controversy because of possible negative economic and social impacts. Therefore, clear assessments of how these initiatives decrease pollutant concentrations are to be provided. Madrid Central is a major initiative of Madrid city council for reducing motor traffic and the associated air pollution in the city centre. This Low Emission Zone starts at the end of 2018, but the first fully-operational period corresponds to the second quarter of 2019. In this work, a methodology based on the Gaussian Process to analyse the evolution of Nitrogen Dioxide inside Madrid Central is undertaken. A Gaussian Process is a stochastic process suitable for interpretable model selection and predictions. Due to its probabilistic nature it provides error estimation at predictions. After the activation of Madrid Central, a relevant reduction of Nitrogen Dioxide has been observed. However, the role of the meteorology during this period must be ascertained to correctly evaluate the role of the activation of the Low Emission Zone against a prone weather. In this work, a model based on the Gaussian Process is trained with meteorological information to predict the concentration of Nitrogen Dioxide at Madrid Central, |$[NO_{2}]$|⁠. This probabilistic description allows extracting statistical information on the reduction affected by the meteorological scenario and separately by the Madrid Central activation. [ABSTRACT FROM AUTHOR]

In this study, the impacts of zinc oxide (ZnO) loading on the selective catalytic reduction (SCR) performance of the cerium oxide-molybdenum oxide (CeOx–MoO3) catalyst were systematically investigated. With the introduction of ZnO, the catalyst's nitrogen oxides (NOx) reduction activity presented a downward trend. At 300 °C, the NOx conversion efficiency of the sample with 4 wt% ZnO loaded dropped below 70%, ~ 22% lower than that of the fresh sample. This decrease was attributed to the neutralization of the catalysts' acid sites by the added ZnO, which inhibited the adsorption of ammonia as the reductant. Furthermore, the introduction of ZnO resulted in a decrease in the relative content of Ce3+, which interfered with the formation of oxygen vacancies and the activation of oxygen. This weakened oxidative ability slowed down the activation of the reactants. Even though the specific surface area of the CeOx–MoO3 catalyst was enhanced due to ZnO, this promotional effect was insufficient to completely overcome the aforementioned negative impacts. Consequently, the efficiency of the NOx elimination process over the ZnO-loaded catalysts was adversely affected. Despite the addition of ZnO, the Eley–Rideal reaction pathway continued to dominate in the deNOx process. [ABSTRACT FROM AUTHOR]

This study investigates real-world carbon dioxides (CO2) and nitrogen oxides (NOx) emissions from diesel (Bharat Stage-IV (BS-IV)) and petrol/gasoline (BS-IV and BS-VI) cars in Indian driving conditions using a portable emission measurement system (PEMS). The paired sample t-test revealed a significant difference (p < 0.05) in NOx and CO2 emissions among the three types of cars, except for CO2 emissions (p > 0.05) between BS-IV petrol and BS-VI petrol cars. The highest NOx emission rates were observed in all car types during acceleration (> 1 m/s2) and deceleration (− 2 m/s2). CO2 emission rates were also high during acceleration (> 1 m/s2) for all car types. At low speeds (around 20 kmph), all car types had low emissions of CO2 and NOx, with acceleration and deceleration rates ranging from − 0.5 to 0.5 m/s2. BS-IV diesel cars emit significantly higher NOx emissions compared to petrol cars, especially at vehicle-specific power (VSP) bin 0 (deceleration to idling mode) and during VSP bin 7 (acceleration mode). BS-IV diesel cars emit 228% and 530% higher NOx emissions than BS-IV and BS-VI petrol cars at VSP bins 0 and 7, respectively. CO2 emissions from BS-VI petrol cars were 10% lower than those from BS-IV petrol cars across all VSP bins, indicating moderate reductions. Furthermore, diesel cars emit 140% less CO2 emissions than petrol cars across various VSP bins. The findings highlight the need for cleaner technologies and responsible driving practices to address vehicular emission concerns. [ABSTRACT FROM AUTHOR]

Urban air pollution is a crucial global challenge, mainly originating from urbanization and industrial activities, which are continuously increasing. Vegetation serves as a natural air filter for air pollution, but adverse effects on plant health, photosynthesis, and metabolism can occur. Recent omics technologies have revolutionized the study of molecular plant responses to air pollution, overcoming previous limitations. This review synthesizes the latest advancements in molecular plant responses to major air pollutants, emphasizing ozone (O3), nitrogen oxides (NOX), and particulate matter (PM) research. These pollutants induce stress responses common to other abiotic and biotic stresses, including the activation of reactive oxygen species (ROSs)-scavenging enzymes and hormone signaling pathways. New evidence has shown the central role of antioxidant phenolic compound biosynthesis, via the phenylpropanoid pathway, in air pollution stress responses. Transcription factors like WRKY, AP2/ERF, and MYB, which connect hormone signaling to antioxidant biosynthesis, were also affected. To date, research has predominantly focused on laboratory studies analyzing individual pollutants. This review highlights the need for comprehensive field studies and the identification of molecular tolerance traits, which are crucial for the identification of tolerant plant species, aimed at the development of sustainable nature-based solutions (NBSs) to mitigate urban air pollution. [ABSTRACT FROM AUTHOR]

In urban environments, various pollutants generated by road traffic, human, and industrial activities degrade outdoor and indoor air quality. Among these pollutants, nitrogen oxides (NOx) are subject to air quality regulations designed to protect human health and the environment. It is therefore crucial to keep their concentration as low as possible. Advanced oxidation processes are a practical choice for the degradation of NOx; among them, heterogeneous photocatalysis has proven to be a viable route. However, while the efficiency of this process has been widely demonstrated on a laboratory scale, it is still the subject of debate for real-life applications. The purpose of this study was to present a new field experiment on the application of a photocatalytic coating to outdoor walls. Air quality monitoring stations were used to evaluate the NOx concentration reduction instead of the chemiluminescent analyzer, in order to increase the number of sampling points. Statistical analysis was carried out to interpret the results. Density probability functions were plotted and showed a positive impact of the coating, leading to lower NOx concentrations. This work was completed by a laboratory-scale assessment of the coating's durability using abrasion, QUV, and immersion/drying tests. The air depollution capacity of the chosen coating was significantly reduced after QUV testing. [ABSTRACT FROM AUTHOR]

The present work analyses the effect of water vapour addition on NO x emissions of premixed hydrogen flames. In doing so, the adiabatic flame temperature is maintained by increasing the equivalence ratio, or alternatively increasing the unburned gas temperature, for increasing levels of water loading. Thus, it is possible to elucidate the changes in NO x production at constant-temperature conditions when the mixture is diluted with water. A consistent reduction of NO x emissions for increasing water dilution can be observed from 1-D premixed freely propagating flame simulations. Regarding the chemical kinetics effect of water vapour, the relative importance of different third-body reactions is examined by modifying the corresponding water collision efficiencies individually. For the chemical mechanism adopted, three reactions directly affect the nitrogen chemistry and the remaining relevant reactions are important for the flame structure and radicals concentration. The analysis stresses the importance of indirect effects like the formation and consumption of O and H radicals in the pre-heat zone, which enhance the subsequent formation of NO x within the flame. The presence of steam can lead to a reduction of approximately 50 % in NO x emissions under conditions close to stoichiometry and high water loading ( 10 % by mass), compared to scenarios without water addition. Furthermore, the efficiency of water in third-body reactions significantly contributes to an emission reduction, and half of NO emissions under the same water loading conditions at high equivalence ratio are observed when the third-body reaction efficiency is activated with respect to the case with zero efficiency. This reduction is primarily attributed to effects on radical concentrations. Finally, the chemical effect via the third-body efficiency of water is examined with respect to flame speed. It turns out that the adiabatic flame temperature plays a key role for the relative influence of the chemical kinetics effect of water dilution. A cross-over temperature is found, below which the chemical effect of water reduces the flame speed, whereas the flame speed is increased above it. [ABSTRACT FROM AUTHOR]

The tropospheric production of O3 is complex, depending on nitrogen oxides (NOx = NO + NO2), volatile organic compounds (VOCs), and solar radiation. We present a case study showing that the O3 concentration is higher in a rural area, 14 km downwind from a coastal town in Central Italy, compared with the urban environment. The hypothesis is that the O3 measured inland results from the photochemical processes occuring in air masses originating at the urban site, which is richer in NOx emissions, during their transport inland.To demonstrate this hypothesis, a feed forward neural network (FFNN) is used to model the O3 measured at the rural site, comparing the modeled O3 and the measured O3 in different scenarios, which include both input parameters related to local O3 production by photochemistry and input parameters associated with regional transport of O3 precursors. The simulation results show that the local NOx concentration is not a good input to model the observed O3 (R = 0.17); on the contrary including the wind speed and direction as input of the FFNN model, the modelled O3 is well correlated with that measured O3 (R = 0.82). [ABSTRACT FROM AUTHOR]

Nonmethane volatile organic compounds (NMVOCs) are important precursors of ozone (O3) formation under sufficient nitrogen oxide conditions. Understanding the characteristics and emission sources of NMVOCs, as well as the relationship between NMVOCs and O3 , is of great significance for effective O3 pollution control. In this study, continuous online monitoring of NMVOCs was carried out in Zhengzhou, Henan, from 1–30 June. Furthermore, the study provided recommendations for strategies aimed at reducing O3 formation. During the observation period, the concentration of total NMVOCs (TNMVOCs) varied from 9.9 to 60.3 ppbv, with an average of 22.8 ± 8.3 ppbv. The average concentration of TNMVOCs during O3 pollution events was higher than on clean days. Six major sources of NMVOCs were identified using the positive-matrix-factorization model. Vehicular exhausts (28 %), solvent usage (27 %), and industrial production (22 %) were the main sources. We explore the O3 –precursors relationship and propose observation-oriented O3 control strategies. The results of the relative incremental reactivity (RIR) and the Empirical Kinetics Modeling Approach show that Zhengzhou was under an anthropogenic volatile organic compound (AVOC)-limited regime. NMVOCs had the largest RIR value, while NOx exhibited a negative RIR value. It is noteworthy that the sensitivity of O3 formation to biogenic volatile organic compounds (BVOCs) was greater than that to AVOCs. Considering the reduction effect, it is recommended that the ratio of AVOCs to NOx be maintained at no less than 3:1 to effectively reduce O3 formation. [ABSTRACT FROM AUTHOR]

Tropospheric ozone (O3) is an important greenhouse gas that is also hazardous to human health. The formation of O3 is sensitive to the levels of its precursors NOx (≡NO + NO2) and peroxy radicals, for example, generated by the oxidation of volatile organic compounds (VOCs). A better understanding of this sensitivity will show how changes in the levels of these trace gases could affect O3 levels today and in the future, and thus air quality and climate. In this study, we investigate O3 sensitivity in the tropical troposphere based on in situ observations of NO, HO2 and O3 from four research aircraft campaigns between 2015 and 2023. These are OMO (Oxidation Mechanism Observations), ATom (Atmospheric Tomography Mission), CAFE Africa (Chemistry of the Atmosphere Field Experiment in Africa) and CAFE Brazil, in combination with simulations using the EMAC atmospheric chemistry—climate model. We use the metric α(CH3O2) together with NO to investigate the O3 formation sensitivity. We show that O3 formation is generally NOx‐sensitive in the lower and middle tropical troposphere and is in a transition regime in the upper troposphere. By distinguishing observations impacted by lightning or not we show that NO from lightning is the most important driver of O3 sensitivity in the tropics. NOx‐sensitive chemistry predominates in regions without lightning impact, with α(CH3O2) ranging between 0.56 and 0.82 and observed average O3 levels between 35 and 55 ppbv. Areas affected by lightning exhibit strongly VOC‐sensitive O3 chemistry with α(CH3O2) of about 1 and average O3 levels between 55 and 80 ppbv. Plain Language Summary: Ozone (O3) in the troposphere is both an air pollutant and a greenhouse gas. It is formed from nitrogen oxides (NOx) and volatile organic compounds (VOCs). The formation can be sensitive to either of these precursors depending on their abundance. Considering the high relevance of O3 in regard to human health and global warming, it is important to understand this sensitivity of O3 formation, which allows to predict future changes in O3. Here, we investigate O3 formation sensitivity toward NOx and VOCs in the tropical troposphere based on aircraft measurements during four research campaigns between 2015 and 2023, and a global model. We include observations of NO, HO2 (hydroperoxyl radicals) and O3 over South America, the Middle East and the Pacific, Atlantic and Indian Ocean. We find that O3 formation is sensitive to NOx in the lower tropical troposphere. In the upper tropical troposphere, lightning events control O3 chemistry and promote strong VOC‐sensitive O3 formation. Key Points: α(CH3O2) correlated with NO is a powerful metric for indicating O3 sensitivity and is valid throughout the troposphereO3 chemistry in the remote tropical lower troposphere is found to be NOx‐sensitiveNO emissions from lightning drive O3 sensitivity in the tropical upper troposphere and induce highly VOC‐sensitive chemistry [ABSTRACT FROM AUTHOR]

Industrialization, modernization, and heavy car populations cause an extensive release of hazardous gases which impact the environment and human health. In this respect, employing gas sensors for detecting different concentrations of carbon oxides, nitrogen oxides, and other harmful gases is being advanced with much interest and necessity. In our current research, we have feasibly synthesized MWCNTs/SnO 2 hierarchical structure through a hydrothermal process. The attained XRD diffraction pattern reflects the crystallinity with a crystallite size <10 nm. The FTIR results signify the presence of the functional group which verifies the successful interaction and connection for the composite network. Morphological features using SEM, HRTEM depict the hierarchical structure persistence. The adsorption/desorption curves are investigated using BET analysis acquiring a surface area of 189 cc/g. Numerous gases were included in the gas sensing study such as ethanol, methanol, acetone, ammonia, CO, and CO 2. The sensing performance displays a remarkable result for carbon monoxide (CO) detection. The response time for CO detection was 5 s, while the recovery was 7s for 300 ppm at RT. The improved selectivity of CO amongst ethanol, CO 2 and other gases is demonstrated. The proposed CO sensing structure combines feasible approach, low-cost, room temperature operation, and fast response/recovery times. The structure is promising for CO gas detection for versatile industrial applications. [ABSTRACT FROM AUTHOR]

In the process of fuel utilization, traditional combustion technologies result in the conversion of nitrogen elements in fuels into nitrogen oxides, which are released into the atmosphere, posing serious threats to the environment and human health. The chemical looping process (CLP) is an effective technology for reducing nitrogen-containing (N-containing) pollutants during fuel utilization. During the CLP, the oxygen carrier (OC) can oxidize nitrogen oxide precursors (NH3 and HCN) released from the fuel to N2, while the reduced OC can reduce nitrogen oxides to N2. The achievement of efficient nitrogen pollutant removal relies on the development of highly active oxygen carriers (OCs). This review summarizes the recent progress in the removal of nitrogen pollutants within chemical looping processes (CLPs). It delineates the formation pathways of N-containing pollutants (NH3, HCN, NO, NO2 and N2O) and highlights the performance of various OCs. The influence of reaction conditions and feedstock characteristics is also discussed. Ni-based OCs have demonstrated superior performance in the removal of N-containing pollutants, exhibiting strong oxidation capabilities and excellent catalytic properties. Moreover, iron ore, as a cost-effective and environmentally friendly feedstock, holds promise for wide-scale application. Future research should focus on further optimizing OCs strategies and refining reaction conditions to achieve more efficient and economical N-containing pollutant removal, thereby fostering the widespread application of chemical looping technology in the energy sector. [ABSTRACT FROM AUTHOR]

Ammonia (NH 3)-hydrogen (H 2) blends which are obtainable by NH 3 cracking can be an eminent carbon-free fuel. To provide a valuable database for the practical application of cracking-based NH 3 -H 2 fuel, the effects of pressure on the combustion characteristics of premixed NH 3 -H 2 (-nitrogen (N 2))/air swirl flames are investigated in terms of H 2 mole fraction in the NH 3 -H 2 blend and fuel-equivalence ratio. Extinction mechanisms at fuel-lean and rich flames are the same for both normal and elevated pressures, though only the blowoff is observed for elevated pressure. With increasing pressure, fuel-rich limits are generally extended but fuel-lean limits are reduced, NO x emissions decrease and the condition of the maximum NO x emissions moves towards fuel-richer condition. Flame visualization exhibits the shifted main reaction zone upstream, the increased flame wrinkling and the reduced OH and NO intensities with increasing pressure. Dilution effects of N 2 at elevated pressure become remarkable compared with those at normal pressure. [Display omitted] • For premixed NH 3 –H 2 (-N 2)/air flames at elevated pressure, only blowoff is observed. • Different fuel-lean and rich limit tendencies with increasing pressure are found. • NO x emissions decrease with increasing pressure. • With increasing pressure, the main reaction zone shifts upstream. • Dilution effects of N 2 are more dominant at elevated pressure than normal pressure. [ABSTRACT FROM AUTHOR]

Ammonia (NH 3) is a promising substitute for fossil fuels to achieve the net-zero emission targets. To improve the combustion performance of NH 3 , reactive fuels are added to the NH 3 combustion. In the present study, the combustions of NH 3 , CH 4 /NH 3 , and H 2 /NH 3 in air conditions were simulated using a reactive molecular dynamics method. Results suggest that whether the addition of CH 4 and H 2 could accelerate the consumption of NH 3 and reduce NO X emissions depends on the fuel ratio of the reactive gas (CH 4 /H 2) and NH 3 molecules. The acceleration of NH 3 consumption is significant at low H 2 /NH 3 fuel ratios and high CH 4 /NH 3 fuel ratios, as the addition of H 2 and CH 4 lowers the activation energy for NH 3 combustion. NO X emissions are mitigated at low H 2 /NH 3 and CH 4 /NH 3 fuel ratios but increase at high fuel ratios. The pathways for NOx generation and de-NOx reactions were identified. This study unveiled the mechanism via which the reactive fuels affect the NH 3 combustion performance from an atomic perspective. The findings will be useful for the design of high-efficiency and low-emission combustion chambers in ammonia-powered energy systems. • A comparative study of effects of H 2 and CH 4 on NH 3 combustion was elucidated. • Pathways of NO X formation and de-NO X reactions were extracted. • A comprehensive understanding was provided between additives and fuels in NH 3 combustion. [ABSTRACT FROM AUTHOR]

The transition from hydrocarbon-based to carbon-free fuels is imperative owing to environmental concerns and stricter regulations. However, the combustion of hydrogen (H 2) and ammonia (NH 3) generates nitrogen oxide (NO) and faces operational constraints. Hence, technologies like flameless and moderate or intense low-oxygen dilution combustion are being explored to mitigate NO formation. This study analyzed flameless combustion of H 2 /NH 3 /N 2 fuel mixture, assessing the impacts of varying fuel velocity, feed strategy, equivalence ratio, and O 2 content on NO emissions. Using a laboratory-scale combustor, flameless combustion was achieved via controlled flow and internal recirculation. Lower fuel velocity improved combustor temperature uniformity and reduced NO emissions. Feeding NH 3 separately decreased NO emissions compared to mixing it with fuel. Decreasing excess O 2 enhanced temperature uniformity, suppressed fuel-NO formation, and reduced NO emissions. N 2 dilution improved fuel-oxidizer mixing, enhancing temperature uniformity and reducing NO emissions, highlighting how parameter optimization enhances temperature uniformity and lowers NO emissions. • We investigated H 2 /NH 3 /N 2 flameless combustion characteristics and NO emissions. • Decreasing the fuel velocity decreased NO emissions. • Feeding ammonia separately decreased NO emissions. • An increased equivalence ratio decreased NO emissions. • A reduced O 2 content in the oxidizer decreased NO emissions. [ABSTRACT FROM AUTHOR]

Among the existing techniques to mitigate the problem of contamination in the indoor environment, photocatalytic technology is considered to be the most promising solution in terms of effectiveness and cost. To that end, in the frame of the LIFEVISIONS project, a novel photocatalytic powder (photo-powder) was mixed in paints' matrix, producing a photocatalytic building material (photo-paint) able to improve indoor air quality (IAQ), upon its application, without downgrading paint physical properties. As a result, of IAQ improvement, less energy will be needed from ventilation systems, addressing not only health issues related to air quality but also energy reduction targets. Many powder formulae were synthesized using different synthetic pathways, concentration of dopants, and TiO2 particles' size. They were tested in a photocatalytic reactor (lab-scale tests), according to EN 16980-1:2021, under visible light and the results showed that the most promising photocatalytic performance degrades 85.4% and 32.4% of nitrogen oxide (NO) and toluene, respectively. This one was used for the production of two different kinds of paints, organic (with organic binder) and inorganic (with potassium silicate binder), in an industrial scale. Both were tested in the Demo Houses' prototype demonstrator (real-scale tests) with an ultimate scope to estimate their effectiveness to degrade air pollutants under real-world conditions. In addition, the reduced energy consumption as a result of less ventilation needs was calculated in Demo Houses. More specifically, the energy reduction based on simulation results on Demo Houses was more than 7%. Although lab-scale tests showed better photocatalytic performance than the real scale, the efficiency of the paints under a more complicated environment was very promising. [ABSTRACT FROM AUTHOR]

This study analyzes the selective productions of nitrogen oxides and ozone in dielectric barrier discharge due to temperature controlled by the dual duty cycle. In this work, we varied the dual duty cycle of the output voltage in the power supply, which alternatively generates distinguished high and low‐temperature modes for selective productions of nitrogen oxides and ozone. The alternating nitric oxide and ozone by dual duty cycle were measured at a maximum of 100 ppm and 100 ppm in the gas phase, respectively. In the evaluation of DI water treated by dual duty cycle, nitrogen oxides, and ozone have been observed simultaneously in the liquid phase. These results offer new insights into the selective production of temperature‐dependent chemical characteristics for advanced plasma applications. [ABSTRACT FROM AUTHOR]

A literature review on oxide compositions developed to modify ceramic aluminosilicate fibers-based filter elements for the selective catalytic reduction of nitrogen oxides during the purification of high-temperature industrial gases is presented. Methods for preparing the catalytic compositions and methods for their introduction into the structure of the ceramic filter elements are also discussed. [ABSTRACT FROM AUTHOR]

We show that the Landsat and Sentinel-2 satellites can detect NO2 plumes from large point sources at 10 to 60 m pixel resolution in their blue and ultrablue bands. We use the resulting NO2 plume imagery to quantify nitrogen oxides (NOx) emission rates for several power plants in Saudi Arabia and the United States, including a 13-y analysis of 132 Landsat plumes from Riyadh power plant 9 from 2009 through 2021. NO2 in the plumes initially increases with distance from the source, likely reflecting recovery from ozone titration. The fine pixel resolutions of Landsat and Sentinel-2 enable separation of individual point sources and stacks, including in urban background, and the long records enable examination of multidecadal emission trends. Our inferred NOx emission rates are consistent with previous estimates to within a precision of about 30%. Sources down to ~500 kg h-1 can be detected over bright, quasi-homogeneous surfaces. The 2009 to 2021 data for Riyadh power plant 9 show a strong summer peak in emissions, consistent with increased power demand for air conditioning, and a marginal slow decrease following the introduction of Saudi Arabia's Ambient Air Standard 2012. [ABSTRACT FROM AUTHOR]

Air pollutants can have a substantial impact on health. Particulate matter (PM10 and PM2.5) can penetrate the respiratory system and produce inflammation; chronic exposure can damage lung tissue. Several environmental and daily habits have been reported to increase the risk of disease and adverse health conditions. We carried out a study to assess the importance and effect of these factors on human health. The objective was to measure exposure to environmental pollutants (PM2.5, PM10, nitrogen dioxide, and noise) by studying cyclists in Montevideo, Uruguay. We measured environmental pollutants on two urban routes with high and low values of the environmental variables and biometrics of participating cyclists. No significant differences were found between routes. Our results suggest that active transport benefits seem to outweigh health risks in Montevideo for the sampled cycling routes. Our study provides knowledge about characteristics of the environment, which is an important input when planning where to place bikeways in Montevideo. [ABSTRACT FROM AUTHOR]

Ozone at ground level (O3) is an air pollutant that is formed from primary precursor gases like nitrogen oxides (NOx) and volatile organic compounds (VOCs). It plays a significant role as a precursor to highly reactive hydroxyl (OH) radicals, which ultimately influence the lifespan of various gases in the atmosphere. The elevated surface O3 levels resulting from anthropogenic activities have detrimental effects on both human health and agricultural productivity. This paper provides a comprehensive analysis of the variations in surface O3 levels across various regions in the Indian subcontinent, focusing on both spatial and temporal changes. The study is based on an in-depth review of literature spanning the last thirty years in India. Based on the findings of the latest study, the spatial distribution of surface O3 indicates a rise of approximately 50–70 ppbv during the summer and pre-monsoon periods in the northern region and Indo-Gangetic Plain. Moreover, elevated levels of surface O3 (40–70 ppbv) are observed during the pre-monsoon/summer season in the western, southern, and peninsular Indian regions. The investigation also underscores the ground-based observations of diurnal and seasonal alterations in surface O3 levels at two separate sites (rural and urban) in Kannur district, located in southern India, over a duration of nine years starting from January 2016. The O3 concentration exhibits an increasing trend of 7.91% (rural site) and 5.41% (urban site), ascribed to the rise in vehicular and industrial operations. This review also presents a succinct summary of O3 fluctuations during solar eclipses and nocturnal firework displays in the subcontinent. [ABSTRACT FROM AUTHOR]

The port of Cartagena, south-east Spain, is noted for its intense activity. This paper presents the influence of the COVID-19 pandemic on the recorded levels of six pollutants. Fifteen years of measurements were used, with two objectives. The first was to investigate how these pollutants evolved, together with their usual cycles. The second objective was to ascertain whether the COVID-19 pandemic had an impact on the concentrations recorded. The results showed that nitrogen oxide concentrations remained steady in the first half of the measurement period and decreased in the second half. SO2 concentrations decreased irregularly, whereas O3 and PM10 presented steady concentrations. The annual cycle was observed for nitrogen oxides and O3. Only SO2 evidenced no weekly cycle. Finally, the analysis of pre- and post-pandemic concentrations revealed a sharp decrease in nitrogen oxides, whereas the pandemic was not seen to have had any impact on the other pollutants. In addition, NO2 emerged as the best indicator of human activity—represented by car and maritime traffic—due to its response to the relaxation measures. Finally, Lamb weather types were calculated. The unclassified type was the most frequent. However, the greatest concentration changes were observed for anticyclonic and eastern flow types. [ABSTRACT FROM AUTHOR]

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Designing a combustion chamber for gas turbines is considered both a science and an art. This study presents a comprehensive methodology for designing an annular combustion chamber tailored to the operating conditions of a CFM-56 engine, a widely used high bypass ratio turbofan engine. The design process involved calculating the basic criteria and dimensions for the casing, liner, diffuser, and swirl, followed by an analysis of the cooling sections of the liner. Numerical simulations using NUMECA software and the HEXPRESS meshing tool were conducted to predict the combustion chamber's behavior and performance, employing the κ-ε turbulence model and the Flamelet combustion model. Methane was used as the fuel, and simulations were performed for three fuel injection angles: axial, 45°, and 60°. Results demonstrate that the combustion chamber is properly dimensioned and achieves complete combustion for all configurations. The pressure ratio is 0.96, exceeding the minimum design criteria. Additionally, the emissions of unburned hydrocarbons are zero, while nitrogen oxides and carbon monoxide levels are below regulatory limits. These findings validate the proposed design methodology, ensuring efficient and environmentally compliant combustion chamber performance. [ABSTRACT FROM AUTHOR]