CO2 Levels Research Articles

Boosting selectivity for multi-carbon products in electrochemical CO2 reduction via enhanced hydroxide adsorption in ultrafine CuOx/CeOx nanoparticles

The electricity-driven reduction of CO2 presents a unique prospect of mitigating atmospheric CO2 levels and converting renewable energy into chemical fuels. However, the lack of an efficient catalyst that can transform CO2 into desired products with appreciable selectivity at commercially relevant current densities (ID) impedes the practical implications of this technology. This work describes a scalable approach for producing ultrafine nanoparticles of CuOx-CeOx (CuCe) composites via rapid coprecipitation under oxygen-deprived conditions. In this process, Ce(OH)3 acts as a reducing agent converting Cu(OH)2 into ultrafine Cu2O nanoparticles. Thus, the Ce: Cu ratio in composite effectively controls the particle size and bulk structural fixture of the CuCe composites. Despite having lower ECSA, The CuCe composites exhibit superior catalytic performance compared to CuO, with significantly higher selectivity for ethanol production and lower selectivity for CO and H2. The Cu1.5Ce prepared using a Cu: Ce ratio of 1.5:1, demonstrated remarkable catalytic activity with Faradaic efficiencies (F. E.) of 34.2 % for ethanol, 44.1 % for ethylene, and 81.08 % for multi-carbon (C2+) products. Moreover, while operating at the ID of 500 mA cm−2, Cu1.5Ce achieves a single pass CO2 conversion (SPCC) of 19.9 %, and a half-cell energy efficiency (E. E. half-cell) of 31.5 % for the C2+ products. It produces the C2+ products at the partial current density (pID) of 405.4 mA cm−2. The superior performance of Cu1.5Ce can be attributed to the improved hydroxide adsorption and partial retention of oxidized copper species under cathodic bias.

Numerical investigation of future potato yields in Bangladesh using Machine learning and IoT

The changing environment has significantly affected Bangladesh for the past several decades, and a number of minerals and nutrients are in short supply in the human population. However, not only are we being affected by the effects of climate change, but also the crops cultivated on our farms are feeling its impact. The nutrient content and growth of food crops are affected by many components of climate change, such as rising temperatures, increased precipitation, rising CO2 levels, etc. It is commonly regarded that potatoes are one of the healthiest and most popular foods in Bangladesh, with an abundance of nutrients and electrolytes that are beneficial to the body. However, in the not-too-distant future, the production of potatoes will be affected by the high temperature and decreased precipitation resulting from climate change. As potatoes are one of the most essential staple foods in Bangladesh, a viable solution must be found for continuous potato production in the country. A comprehensive examination of the evolution, production, and important nutrients of potatoes will be performed in this study. A range of sensors, networks, drones, cameras, and applications will be collected for the purpose of monitoring the potato field and ensuring that the crops are cultivated in an acceptable environment. This idea can aid our country economically and agriculturally by increasing potato production. Potatoes are affordable for consumers from all socioeconomic classes. Through this idea, Producers will achieve a successful harvest of nutrient-rich potatoes for public consumption.

Analysis of the Interplay between Indoor Air Quality and Thermal Comfort in University Classrooms for Enhanced HVAC Control

While aspects of indoor environmental quality, such as thermal comfort, indoor air quality (IAQ), acoustic, and visual comfort, are usually studied separately, their interactions are crucial yet often overlooked. Understanding how these factors influence each other is essential for a comprehensive perception of the indoor environment. This paper investigates the relationship between indoor air quality (IAQ) and thermal comfort using an extensive field investigation conducted in university classrooms during the heating season, collecting 712 samples of subjective responses correlated with environmental measurements. Key findings reveal significant correlations between subjective responses related to the thermal environment and those related to air quality. Perceived control over the thermal environment shows stronger correlations with IAQ responses than with thermal responses, particularly with perceived ventilation (r = 0.41), COVID-19 risk (r = 0.28), and air quality (r = 0.28). Additionally, environmental parameters demonstrate stronger correlations with thermal responses than with IAQ responses. Higher CO2 concentration is associated with increased thermal sensation and decreased thermal preference and perceived control. Conversely, IAQ responses remain relatively stable with changes in indoor operative temperature. The difference between the operative temperature to which the occupants are exposed and their expressed neutral temperature widens as CO2 concentration rises, indicating a reduced adaptive capacity of occupants which is associated with increasing CO2 levels. These insights are crucial for providing HVAC system management strategies that consider the interaction between different aspects of IEQ, aiming to improve occupants’ well-being and reduce energy consumption.

Buzzing towards Resilience: Investigating the Spatial Alignment of the Desert Pallid Bee, Centris pallida, and Its Host Plants in Response to Climate Change.

Wild bees are vital for the pollination of native plants and crops, providing essential ecosystem services. Climate change is known to impact biodiversity and species distributions, but insects adapted to desert ecosystems may exhibit unique physiological, behavioral, and evolutionary responses. The desert pallid bee (C. pallida), a solitary bee native to the arid southwestern United States and northern Mexico, primarily forages on yellow palo verde (P. microphylla), blue palo verde (P. florida), and desert ironwood (O. tesota). This study used MaxEnt to estimate the current and projected geographical overlap of suitable habitats for C. pallida and its host plants. Here, we used MaxEnt to estimate the current and forecasted overlapping geographically suitable habitat of C. pallida with all three host plants. We forecasted potential environmentally suitable areas for each species to the year 2040 using the current distribution model and climate projections with moderate CO2 levels. We found a continued spatial alignment in the suitable area of the bee and its host plants with a 70% increase in the range overlap area, though shifted to higher average altitudes and a slight northern expansion. These findings may provide insight to stakeholders on the conservation needs of desert-dwelling pollinators.

Optimization methodology combining Taguchi design and response surface method to maximize a compression ignition engine efficiency fueled with oxygenated synthetic fuel

This research examines the potential of a synthetic e-diesel and oxymethylene dimethyl ether blend in a heavy-duty single-cylinder engine. The main purpose is to find the optimal engine settings that maximize engine efficiency and minimize emissions. As the first step, a methodology was developed and applied to simplify the engine’s map into five characteristic points to be representative of the World Harmonized Transient Cycle, assigning weights to each load region. This simplification reported low error estimations for fuel consumption and NOx emissions over the cycle. After obtaining the five points, a drop-in analysis was assessed, where the fuel was evaluated with the same settings as diesel, revealing more advanced and shorter combustion with great reductions in soot emissions. Then, a group of three air management and three injection parameters was selected for optimization. A novel methodology combining Taguchi Design and Response Surface Methodology is developed and applied to find the best engine settings. By integrating these two methods, the research reduced the number of required experiments if only one method were used and maintained the goal of achieving higher thermal efficiencies with the new fuel blend compared to the diesel baseline. Significant statistical results were obtained in the Taguchi design, revealing the air management factors that most affected the responses; meanwhile, second-order models with high accuracy helped in finding the best injection parameters. Subsequently, the best settings were experimentally evaluated, and optimal conditions determined by the two methods were validated, confirming the effectiveness of the methodology. Optimization results revealed an improvement of around 2% higher efficiencies for the five tested points while achieving important average reductions of 28% less in NOx with additional decreases in CO, HC, and soot levels, all outperforming traditional diesel benchmarks. Finally, a well-to-wheel analysis using the simplified cycle confirmed a substantial reduction in carbon impact when replacing diesel with this alternative fuel. The successful application of this methodology to recalibrate an engine with an alternative fuel blend shows the potential of using these fuels in existing engines and offers a novel methodology that can be escalated and applied under the engine calibration context.

Tuning the crystallinity of Cu-based electrocatalysts: Synthesis, structure, and activity towards the CO2 reduction reaction

The rising levels of CO2 have spurred growing concerns for our environment, and curbing CO2 emissions may not be practically viable with the expanding human population. One attractive strategy is the electrochemical CO2 reduction (CO2RR) into value added chemicals but because of the chemical inertness of the CO2 molecule, the electrochemical reduction requires a suitable catalyst. Cu-based catalysts have been largely investigated for CO2RR, however, the difficulty achieving a high selectivity and faradaic efficiency towards specific products, especially hydrocarbons, is still a challenge, alongside the concern over cost, stability and scarcity of the metal catalyst. The present research focuses on tuning the crystallinity of Cu nanoparticles via a green, cost-friendly, and facile method, called the urea glass route. Remarkably, the incorporation of a selected nitrogen-carbon rich source (namely, 4,5 dicyanoimidazole) at low temperatures allow the formation of an oxidized derived amorphous Cu system, whilst a second thermal treatment enables the transformation to crystalline Cu0. We found that the combination of surface Cu0 and Cu1+ (observed via XPS studies) present in our amorphous and crystalline Cu nanoparticles leads to interesting differences in the final catalytic activity when tested under CO2 reaction conditions. The combination of extended X-ray absorption fine structure (EXAFS) experiments and molecular dynamics simulations provides compelling evidence for the amorphous and metallic nature of Cu nanoparticles.

Geochemistry in Geological CO2 Sequestration: A Comprehensive Review

The increasing level of anthropogenic CO2 in the atmosphere has made it imperative to investigate an efficient method for carbon sequestration. Geological carbon sequestration presents a viable path to mitigate greenhouse gas emissions by sequestering the captured CO2 deep underground in rock formations to store it permanently. Geochemistry, as the cornerstone of geological CO2 sequestration (GCS), plays an indispensable role. Therefore, it is not just timely but also urgent to undertake a comprehensive review of studies conducted in this area, articulate gaps and findings, and give directions for future research areas. This paper reviews geochemistry in terms of the sequestration of CO2 in geological formations, addressing mechanisms of trapping, challenges, and ways of mitigating challenges in trapping mechanisms; mineralization and methods of accelerating mineralization; and the interaction between rock, brine, and CO2 for the long-term containment and storage of CO2. Mixing CO2 with brine before or during injection, using microbes, selecting sedimentary reservoirs with reactive minerals, co-injection of carbonate anhydrase, and enhancing the surface area of reactive minerals are some of the mechanisms used to enhance mineral trapping in GCS applications. This review also addresses the potential challenges and opportunities associated with geological CO2 storage. Challenges include caprock integrity, understanding the lasting effects of storing CO2 on geological formations, developing reliable models for monitoring CO2–brine–rock interactions, CO2 impurities, and addressing public concerns about safety and environmental impacts. Conversely, opportunities in the sequestration of CO2 lie in the vast potential for storing CO2 in geological formations like depleted oil and gas reservoirs, saline aquifers, coal seams, and enhanced oil recovery (EOR) sites. Opportunities include improved geochemical trapping of CO2, optimized storage capacity, improved sealing integrity, managed wellbore leakage risk, and use of sealant materials to reduce leakage risk. Furthermore, the potential impact of advancements in geochemical research, understanding geochemical reactions, addressing the challenges, and leveraging the opportunities in GCS are crucial for achieving sustainable carbon mitigation and combating global warming effectively.

Acute freshwater CO2 exposure does not impair seawater transfer in three different sizes of Atlantic salmon (Salmo salar) subjected to different photoperiod manipulations.

There is a growing interest in Atlantic salmon (Salmo salar) aquaculture to extend the time fish are reared in freshwater (FW) recirculating aquaculture systems (RAS), producing larger FW salmon that can then be induced to undergo smoltification before transfer into marine net pens for grow-out and harvest. Smolts can be produced by photoperiod (PT) manipulation in RASs, but little is known about how delaying smoltification to larger body sizes affects susceptibility to elevated CO2 levels (hypercapnia), which can occur at high stocking densities in FW RAS or during transport from FW RAS rearing facilities to marine net pens. To address this, Atlantic salmon were reared from hatch to one of three different sizes (~230, ~580, or ~1300 g) in FW (3 ppt) under continuous light (24:0, light:dark). Once fish reached the desired sizes, a group of salmon were maintained on continuous light 24L:0D to serve as a control salmon. A second group of salmon were exposed to 8 weeks of 12L:12D and then to 4 weeks of 24L:0D to serve as PT treatment salmon, which is the PT manipulation commonly used in Atlantic salmon aquaculture to induce smoltification. At the end of PT manipulation, both control and PT treatment salmon were exposed to 0% or 1.5% CO2 (30 mg/L) for 96 h in FW and then transferred to air-equilibrated seawater (SW, 35 ppt, normocapnia). Salmon were sampled at the end of the 96-h FW CO2 exposure and at 24 h and 7 days in SW for measurements of blood ion/acid-base status, muscle water content (MWC), and gill and kidney Na+/K+ ATPase (NKA) activity. Exposure to 96 h of CO2 in FW resulted in acid-base disturbances in fish from all three size classes, with decreases in blood pH and increases in blood PCO2 and plasma [HCO3 -] but no mortality. Despite these large acid-base disturbances in FW, after transfer to normocapnic SW, there were no significant effects of CO2 exposure on extracellular blood pH, intracellular red blood cell pH, or plasma osmoregulatory status for all three sizes of post-smolt salmon. In general, SW transfer was associated with significant increases in plasma ions and osmolality, as well as gill and kidney NKA activity after 24 h and 1 week in SW with no significant impacts between different sizes of salmon. Thus, exposure to 30 mg CO2/L that mimics levels experienced during transport from FW RAS to an SW transfer site may have minimal effects on Atlantic salmon smolts up to 1300 g.

Indirect markers of muscle damage in military physical training session with neuromuscular and aerobic exercises in circuit (Cross operational): acute effects and recoverability

The Brazilian army recently developed the military physical training “Cross Operational” (CO), composed of four different difficulty levels. The moderate/high intensity character of CO can damage the muscle fibers, characterized by alterations at the cellular level, which can be evaluated indirectly by intramuscular proteins showing up in the bloodstream. In this context, the analysis of muscle damage biomarkers can be used as part of an initial injury prevention tool and in the evaluation of training progression and post-exercise recovery. This study aimed to observe the acute effect of CO on indirect markers of muscle damage in military personnel of the Brazilian army. Twenty-four male recruits aged between 18 and 26 years participated in the study. The four sessions corresponding to the CO levels were performed in cross-design, with a seven-day washout period, and blood samples were collected at rest, immediately after, 24 and 48 hours after each training session. The measured markers were creatine kinase (CK), myoglobin (Mb) and lactate dehydrogenase (LDH). In all CO levels, CK had a significant increase 24 hours after CO, whereas Mb and LDH incresead immediately after CO. Regarding recovery time, LDH returned to baseline values within 48 hours in all levels, whereas CK and Mb, after 48 hours of recovery, reduced but did not return to baseline in level 4. The serum elevations of the biomarkers studied, like those found in studies with other consolidated physical training methods, suggest that CO can contribute to the improvement of the physical training of military personnel.

Common tenrecs (Tenrec ecaudatus) reduce oxygen consumption in hypoxia and in hypercapnia without concordant changes to body temperature or heart rate.

Common tenrecs (Tenrec ecaudatus) are fossorial mammals that use burrows during both active and hibernating seasons in Madagascar and its neighboring islands. Prevailing thought was that tenrecs hibernate for 8-9months individually, but 13 tenrecs were removed from the same sealed burrow 1m deep from the surface. Such group hibernation in sealed burrows presumably creates a hypoxic and/or hypercapnic environment and suggests that this placental mammal may have an increased tolerance to hypoxia and hypercapnia. Higher tolerances to hypoxia and hypercapnia have been documented for other mammals capable of hibernation and to determine if this is the case for tenrecs, we exposed them to acute hypoxia (4h of 16 or 7% O2), progressive hypoxia (2h of 16, 10 and 4% O2), or progressive hypercapnia (2h of 2, 5 and 10% CO2) at cold (16°C) or warm (28°C) ambient temperatures (Ta). Oxygen equilibrium curves were also constructed on the whole blood of tenrecs at 10, 25, and 37°C to determine if hemoglobin (Hb)-O2 affinity contributes to hypoxia tolerance. In animals held at 16°C, normoxic and normocapnic levels of oxygen consumption rate ( ), body temperature (Tb), and heart rate (HR) were highly variable between individuals. This inter-individual variation was greatly reduced in animals held at 28°C for oxygen consumption rate and body temperature. Both hypoxia (acute and progressive) and progressive hypercapnia led to decreases in as well as the variation in between animals held at 16°C. The fall in oxygen consumption rate in 7% O2 independent of changes in body temperature in tenrecs held at 16°C is unique and not consistent with the typical hypoxic metabolic response seen in other hibernating species that depends on concomitant falls in Tb. In animals held at 28°C, exposure to O2 levels as low as 4% and CO2 levels as high as 10% had no significant effect on , HR, or Tb, indicative of high tolerance to both hypoxia and hypercapnia. High variation in heart rate remained between individuals in all gas compositions and at all temperatures. Tenrec Hb-O2 affinity was similar to other homeothermic placental mammals and likely does not contribute to the increased hypoxia tolerance. Ultimately, our results suggest changes in Ta dictate physiological responses to hypoxia or hypercapnia in tenrecs, responses more characteristic of reptiles than of most placental mammals. Given that numerous anatomical and physiological characteristics of tenrecs suggest that they may be representative of an ancestral placental mammal, our findings suggest the typical hypoxic metabolic response evolved later in mammalian evolution.

Deep Forest Modeling: An Interpretable Deep Learning Method for Mineral Prospectivity Mapping

AbstractAccurate mineral prediction is crucial for reducing costs and uncertainties in mineral discovery and extraction. The use of artificial intelligence and big data has advanced mineral prediction into intelligent forecasting. Machine learning methods have shown significant promise in enhancing outcomes. Currently, neural network‐based approaches dominate deep learning (DL), but they lack interpretability and have high modeling complexity, making them less effective for complex problems and time‐consuming. Deep Forest, an innovative DL paradigm, addresses these issues by dynamically adjusting complexity and providing importance assessments for predictive factors. This study focuses on the North American Cordillera, known for its rich geological data and potential for porphyry copper deposits (PCDs). Predictions are made using Deep Forest with factors like Euclidean distance between faults and magmatic rock, fault line density, gravity anomalies, and stream‐sediment geochemical data. Deep neural networks, random forest, convolutional neural networks, transformer model and graph convolutional networks are also used for comparison. Deep Forest shows high performance and can avoid the black box problem of DL without relying on other tools in DL, providing a new perspective for the development and application of other non‐neural network DL models for mineral prediction. Feature importance analysis shows that geological structure and magmatism significantly influence PCD prediction. Elevated levels of elements like Al, Co, and Cr in stream sediments help identify mineralization‐related alterations. These findings underscore Deep Forest's capability to accurately and efficiently guide mineral exploration, highlighting its potential as a promising approach for mineral prospecting.

Protocols for bulk off-line fluid inclusion extraction for the analysis of δ13C-CH4 and δ13C-CO2 using a cavity ring-down spectroscopy (CRDS) analyser

Fluid inclusions are a window into deep geological fluids, providing unique access to their nature and composition. The isotopic composition of CO2 and CH4 hosted in fluid inclusions is a powerful proxy to assess the origin and transformation of deep geological fluids, giving insights into carbon sources, fluxes, and degassing in a wide variety of geodynamic settings. Over the last 5 decades, techniques have been developed to extract fluid inclusions from their host minerals and measure their bulk composition. These techniques are often challenged by analytical artifacts including high blank levels of CO2 and CH4, fluid re-speciation, gas adsorption, and diffusion. Since these processes may alter the pristine composition of gases liberated from fluid inclusions, rigorous protocols are needed in order to evaluate the isotopic integrity of the extracted volatile species. In this study, we introduce new protocols for bulk off-line fluid inclusion extraction for the analysis of δ13C-CH4 and δ13C-CO2 using a Cavity Ring-Down Spectroscopy (CRDS) analyser (Picarro G2201-i). Two mechanical fluid extraction techniques are compared: ball milling in ZrO2 jars and sample crushing in a stainless steel sealed tube under a hydraulic press. Blanks and isotopically labelled tests with the ball milling technique suggest that rotation speed, grinding stock filling degree and filling type alter the CH4 and CO2 concentrations and isotopic compositions measured by the CRDS analyser. In contrast, the crushing technique does not generate measurable quantities of blank CH4 and CO2. The protocols presented in this study allow to extract, detect, and analyse δ13C of CH4 and CO2 for concentrations above 10 and 1,000 ppm respectively. Interlaboratory experiments allowed to replicate previously measured δ13C-CH4 values in natural fluid inclusions within 1‰ with both extraction techniques. This study highlights the potential of combining simple bulk off-line fluid inclusion extraction techniques with a CRDS analyser for δ13C analysis of CO2 and CH4 without gas separation being required.

8226 A Diagnostic Challenge: Factitious Hypobicarbonatemia in Severe Hypertriglyceridemia

Abstract Disclosure: U. Rafat: None. S. Azmat: None. M. Siddiqui: None. R. Alshantti: None. D. Kircheva: None. V. Trendafilova: None. Background: Serum CO2 levels measured by a chemistry analyzer usually correlate with calculated bicarbonate levels on an ABG. There are some instances however, when this is not the case. Severe hypertriglyceridemia can cause serum bicarbonate levels to appear falsely low on metabolic panel. Clinical Case: A 48-year-old man was referred to Endocrinology Clinic for evaluation of hypogonadism and severe hypertriglyceridemia. Routine labs revealed a plasma CO2 of 11 mmol/L (20-31). Na was 133 mmol/L (136-145), K was 4.4 mmol/L (3.5-4.7), Chloride was 101 mmol/L (98-109) and anion gap was 25 (8-20) measured using a Siemens Vista enzymatic chemistry analyzer. His triglycerides were > 1100 mg/dL (0-150), above upper detection limits of the analyzer. The patient reported fatigue and mild abdominal pain. He was admitted to the hospital for further evaluation. His lipase was 41 U/L (12-73), lactic acid 1.2 mmol/L (0.50-2.20). ABG showed pH of 7.41, HCO3 of 26.6 mmol/L (22-29), and anion gap of 7 (10-20). The patient was well-appearing with normal vital signs and normal physical exam. He was made NPO and started on pravastatin, fenofibrate and fish oil. Once his triglycerides were < 1000 mg/dL, he was started on a very low-fat, low-carbohydrate diet. The CO2 level on BMP normalized on day 3 of hospitalization, when triglycerides measured 1010 mg/dL. No other treatment was given for the low CO2 levels. It does not appear that other lab indices were significantly affected by the hypertriglyceridemia. Review of Literature: A BMP measures serum total carbon dioxide using a chemistry analyzer using either an enzymatic/spectro-photometric method, or an electrode-based method; an ABG sample calculates plasma bicarbonate with the Henderson-Hasselbach equation, using the pH and partial pressure of pCO2 in the sample. Enzymatic analyzers measure CO2 using spectrophotometry and decrease in light absorbance is proportional to the sample’s CO2 levels. It is postulated that severely high triglycerides can interfere with this reaction and cause spuriously low CO2 levels, a phenomenon called pseudohypobicarbonatemia. One proposed mechanism for interference with the enzymatic assay method is turbidity causing a falsely low measured CO2 level. Verghese et al found that the severity of the CO2 measurement error positively correlates with the severity of triglyceride elevation. Conclusion: Awareness of the phenomenon of hypertriglyceridemia-induced pseudohypobicarbonatemia can prevent misdiagnosis or delays in diagnosis, as well as unwarranted testing and treatment. Presentation: 6/3/2024

A Pilot Feasibility Study of Delivering a Quit & Win Tobacco-Free Contest in Community Mental Health Programs.

Quit & Win contests are a community-based tobacco cessation strategy that has demonstrated success in supporting tobacco cessation efforts in the general population. However, such contests have not been implemented and evaluated among people living with mental illnesses (MIs). This pilot study aimed to evaluate the feasibility of implementing Quit & Win contests in terms of program delivery, engagement, and cessation outcomes among people with MIs. A single-group posttest design to evaluate the feasibility of Quit & Win contests conducted at three community mental health programs. Flyers introducing the contest were posted at study sites 2 weeks prior to recruitment. Recruitment occurred on 2 days over a 2-week period. Eligible participants received a pamphlet with information about tobacco treatment resources. At the follow-up, postsurveys and expired CO levels were obtained. Participants (N = 28) were mostly male, Non-Hispanic White, with a high school or higher education, unemployed, and 46.4% had a primary substance use disorder diagnosis. Among those who engaged in the program, seven (25.0%) returned for the follow-up, of which three (42.9%) successfully stopped cigarette use. Four (57.1%) described using nicotine replacement therapy in their attempt to stop using cigarettes. Challenges to cessation included difficulty finding available tobacco treatment programs, limited access to treatment medications, and experiencing nicotine withdrawal symptoms. Our findings suggest the feasibility of Quit & Win interventions in community mental health settings. Further efforts are required to enhance recruitment, engagement, and retention, and to support access to community-based tobacco treatment resources.

Estimating daily road traffic pollution in Hong Kong using CFD modelling: Validation and application

Road traffic is a major source of urban air pollution, exposing residents to harmful levels of pollutants, particularly in densely populated urban centers. In this study, Computational Fluid Dynamics (CFD) modelling is applied to investigate the impact of road traffic emissions on air pollution within a dense urban environment. The model, applied in Mong Kok, Hong Kong, incorporates high-resolution traffic activity, meteorological, and background concentration data. It demonstrates strong agreement with roadside measurements, deviating by 18.8 % for NOx, 15.5 % for CO, and 0.7 % for PM10, with potential underestimation linked to unmodeled NOx-O3 photochemistry during midday hours (12:00–17:00). Results reveal that local road traffic significantly increases background NOx levels (41 % average increase), highlighting the importance of dispersion modelling for accurate pollution assessments. Traffic-induced increases in CO and PM10 background levels are less pronounced. Two applications demonstrate the model's utility. Firstly, analysis of daily pollution distribution reveals that approximately 10 % of the studied area experiences moderate to very high pollution levels during peak hours. Secondly, an investigation into pollution sources within a leisure park identifies heavy-duty and light-duty vehicles as the primary NOx polluters. This modelling approach provides a valuable decision-making tool for policymakers and local authorities. It enables the assessment of urban design changes, strategic placement of sensitive structures, and future traffic fleet composition choices to mitigate pollution exposure. As air quality regulations tighten, this study offers a robust method for guiding impactful mitigation strategies.

Elevated O3 has stronger effects than CO2 on soil nematode abundances but jointly inhibits their diversity in paddy soils

Anthropogenic activities have resulted in rising atmospheric concentrations of carbon dioxide (CO2) and ozone (O3), exerting substantial direct and indirect impacts on soil biodiversity within agroecosystems. Despite the considerable attention given to the individual impacts of elevated CO2 and O3 levels, the combined effects on soil nematode communities have not been extensively explored. In this study, we investigated the interactive effects of elevated CO2 (+200 ppm, eCO2) and O3 (+40 ppb, eO3) levels on the abundance, diversity, and trophic composition of soil nematode communities associated with two rice cultivars (Nanjing 5055, NJ5055 and Wuyujing 3, WYJ3). Our findings revealed that soil nematodes had greater abundances under eO3, whereas eCO2 had no significant impacts. Conversely, both eCO2 and eO3, and their combination led to significant reductions in nematode generic richness, accompanied by a decline in the diversity particularly associated with the WYJ3 cultivar. Moreover, eCO2 and eO3 influenced nematode community composition and environmental factors, particularly for the WYJ3 cultivar. Both eCO2 and eO3 significantly increased soil nitrate levels. The changes in nematode community composition were related to soil nitrate levels, as well as nitrogen and carbon concentrations in rice plant roots. Furthermore, interactions between eCO2 and eO3 significantly impacted soil nematode abundance and trophic composition, revealing intricate consequences for soil nematode communities that transcend predictions based on single-factor experiments. This study unveils the potential impacts posed by eCO2 and eO3 on soil biodiversity mediated by rice cultivars, plant functional characteristics and soil feedback mechanisms, thereby underscoring the complex and interactive outcomes arising from concurrent drivers of climate change within the soil food web.

Numerical Investigations on Reducing Unburned Hydrocarbon and Carbon Monoxide Emissions in Reactivity-Controlled Compression Ignition Using Partial Reactivity Stratification with Alternative Fuels and Additive

<div>A numerical investigation has been performed in the current work on reactivity-controlled compression ignition (RCCI), a low-temperature combustion (LTC) strategy that is beneficial for achieving lower oxides of nitrogen (NO<sub>x</sub>) and soot emission. A light-duty diesel engine was modified to run in RCCI mode. Experimental data were acquired using diesel as HRF (high-reactivity fuel) and gasoline as LRF (low reactivity fuel) to check the accuracy and fidelity of predicted results. Blends of ethanol and gasoline with DTBP (di-tert-butyl peroxide) addition in a small fraction on an energy basis were used in numerical simulations to promote ignitability and reactivity enhancement of PFI charge. Achieving stable, smooth, and gradual combustion in RCCI is challenging at low loads, especially in light-duty engines, due to misfiring and poor combustion stability. DTBP is known for enhancing cetane number and accelerating combustion, and it is mixed in a PFI blend to avoid combustion deterioration. The factors governing reactivity stratification to achieve optimal combustion phasing were investigated in the present study. DTBP decomposition and its low-temperature oxidation chemistry were found to be responsible for affecting combustion phasing, heat release patterns, and emission trends. DTBP additive and different in-cylinder strategies were applied and studied to reduce unburned emissions. Adopting a multiple injection approach utilizing dual-pulse assisted in reducing HC and CO levels. It enhances combustion quality by providing adequate control over combustion phasing. Altering operating parameters like intake temperatures reduced HC, CO, and soot emissions by 97.6%, 57.6%, and 52.8%, respectively, compared to baseline gasoline/diesel RCCI data. Optimizing the injection timings of the first and second pulse helps achieve optimal combustion phasing and a 72.95% reduction in NO<sub>x</sub> emissions. The higher injection pressure of DI helped lower the CO and soot emissions by 53.33% and 51.84%, respectively.</div>

The Impact of Hydrogen on Flame Characteristics and Pollutant Emissions in Natural Gas Industrial Combustion Systems

To improve energy savings and emission reduction in industrial heating furnaces, this study investigated the impact of various molar fractions of hydrogen on natural gas combustion and compared the results of the Non-Premixed Combustion Model with the Eddy Dissipation Combustion Model. Initially, natural gas combustion in an industrial heating furnace was investigated experimentally, and these results were used as boundary conditions for CFD simulations. The diffusion flame and combustion characteristics of natural gas were simulated using both the non-premixed combustion model and the Eddy Dissipation Combustion Model. The results indicated that the Non-Premixed Combustion Model provided simulations more consistent with experimental data, within acceptable error margins, thus validating the accuracy of the numerical simulations. Additionally, to analyze the impact of hydrogen doping on the performance of an industrial gas heater, four gas mixtures with varying hydrogen contents (15% H2, 30% H2, 45% H2, and 60% H2) were studied while maintaining constant fuel inlet temperature and flow rate. The results demonstrate that the Non-Premixed Combustion Model more accurately simulates complex flue gas flow and chemical reactions during combustion. Moreover, hydrogen-doped natural gas significantly reduces CO and CO2 emissions compared to pure natural gas combustion. Specifically, at 60% hydrogen content, CO and CO2 levels decrease by 70% and 37.5%, respectively, while NO emissions increase proportionally; at this hydrogen content, NO concentration in the furnace chamber rises by 155%.

Effects of CO2 on the Nitrogen Isotopic Composition of Marine Diazotrophic Cyanobacteria

AbstractBiological N2 fixation has been crucial for sustaining early life on Earth. Very negative δ15N values detected in Archean sediments, which are not observed in present‐day environments, have been attributed to the low efficiency of proto‐nitrogenases. Alternatively, variations in early atmospheric CO2 may also play a role. Here we examine the effects of CO2 concentrations on the biomass δ15N signatures of the diazotrophs Trichodesmium erythraeum and Crocosphaera watsonii, which utilize Mo‐Fe nitrogenase (the most common form of the enzyme). Our results show that these organisms produce biomass with δ15N values up to ∼3‰ lower under both decreased and elevated CO2 concentrations compared to modern levels (∼380 μatm). These deviations from modern CO2 levels reduce nitrogenase enzyme efficiency, leading to increased organismal isotopic fractionation during N2 fixation. This study offers an alternative explanation for the observed fluctuations in geological δ15N records and provides new insights into the past nitrogen cycle on Earth.

Comparison of end tidal CO2 levels between automated head up and conventional cardiopulmonary resuscitation: A pre-post intervention trial

BackgroundThe combination of controlled automated head/thorax elevation, active compression-decompression (ACD) cardiopulmonary resuscitation (CPR), and an impedance threshold device (ITD-16), termed AHUP-CPR, lowers intracranial pressure and increases circulation and neurologically-sound survival in pigs versus conventional (C) CPR. This study examined whether AHUP-CPR increased end tidal (ET) CO2, a non-invasive marker of cardiac output and organ perfusion, compared with C-CPR in witnessed out-of-hospital cardiac arrest patients. MethodWe conducted a prospective, single-arm, pre-post intervention trial in France between October 2019 and October 2022.Firefighters treated patients enrolled during the pre-intervention period with manual C-CPR and with AHUP-CPR during the post-intervention period. Advanced life support was provided by a physician-staffed 2nd-tier response vehicle for the two study periods. The primary outcome was the peak ETCO2 value measured during CPR. Results122 patients with a mean age of 67 years (standard deviation [SD], 17) were enrolled (59 in the pre-intervention period and 63 in the post-intervention period). Based on an intention-to-treat analysis, mean baseline ETCO2 values were comparable between pre- (20.1 mmHg, SD,16.3) and post-(19.2 mmHg, SD, 16.3) intervention periods. Mean peak ETCO2 values during CPR were 30.3 mmHg (SD, 13.1) versus 40.7 mmHg (SD, 17.8) for the pre- and post-intervention study periods (mean difference, 10.6, 95% confidence interval, 4.6 to 16.1, P < 0.001). Mean differences in peak ETCO2 between study periods did not vary according to the first recorded cardiac rhythm (P for interaction = 0.99). The proportion of return of spontaneous circulation [19 (32.2%) vs. 21 (33.3%)], survival on hospital admission [17 (28.8%) vs. 19 (30.2%)], and 30-day survival with favorable neurological outcome [8 (13.6%) vs. 7 (11.1%)] did not differ between study periods. ConclusionETCO2 values during AHUP-CPR reached the range of non-arrest normal physiological levels and were significantly higher than with C-CPR, regardless of the presenting cardiac rhythm.