Search

The electrocatalytic CO2 reaction with other gases to synthesize value-added products at high current densities is challenging due to the limited diffusion rate for low-solubility gases in aqueous electrolytes. To enhance the mass transfer process, herein, a membrane electrode assembly (MEA) electrolyzer is employed to achieve high-rate electrochemical C–C coupling of CO2 and gaseous formaldehyde. Based on the simultaneous gas-phase delivery of reactants to the catalytic surface, an acetate production rate of 654 mg L−1 h−1 is achieved at a current density over 150 mA cm−2 on a Cu-MOF coated Cu2O catalyst. In situ FT-IR, Raman spectroscopy, and in situ XAFS combined with DFT suggest that the energy barrier of C–C coupling between *CO and *CH2OH is significantly lowered due to the insertion of Cu-MOF, thus promoting the production of acetate. This work provides a novel strategy for electrochemical treatment of waste gas coupling to synthesize high-value products with potential industrial applications. [ABSTRACT FROM AUTHOR]

Formation and NO emission of hydrogen-enriched methane combustion in the swirl flame and moderate or intense low-oxygen dilution (MILD) modes inside a 10-kW operating furnace are experimentally and numerically investigated, especially in the dependence of NO emission on wall temperature (T wall), exhaust gas temperature (T ex), and furnace temperature (T fur) and NO formation/reduction via different sub-mechanisms. Results show that the formation of MILD combustion at 20 vol% H 2 requires wall temperatures above ∼868 K. In MILD combustion, NO formation mainly occurs outside the flame front downstream from the burner exit, and T wall , T ex , and T fur can be used to scale NO emissions. However, in swirl flame combustion, thermal NO is the major NO production source and is formed mainly in the high-temperature region near the burner exit; also, only T fur is applicable for scaling NO emission. NO reduction by HCCO/CH i = 0-3 and/or H becomes more important in MILD combustion than swirl flame combustion. • The formation and NO emission of CH 4 /H 2 swirl and MILD combustion are investigated. • The formation of MILD combustion at 20 vol% H 2 needs wall temperatures above ∼868 K. • NO emission can be scaled by T wall , T ex , and T fur in MILD combustion. • NO reaction pathways in CH 4 /H 2 swirl and MILD combustion are separately analyzed. [ABSTRACT FROM AUTHOR]

Two bio-trickling filters (BTFs) were set up for ethyl acetate removal: one of the filters contained a built-in proton exchange membrane (M-BTF), and the other contained the conventional structure (O-BTF). The comparative results showed that M-BTF had superior biodegradation capacity. Its start-up was relatively faster, and it produced more biomass and exhibited a higher removal efficiency, achieving a maximum removal efficiency difference of 9.9 % than O-BTF. Meanwhile, the maximum output voltage of 536 mV was obtained with the corresponding removal loading of 249.3 g•m−3•h−1. The intermediate product was detected to explore the possible degradation pathway of ethyl acetate, and results showed that the degradation of ethyl acetate was accompanied by the synthesis of long-chain hydrocarbons. The microbial analysis revealed that the anode electrode was highly selective to the bacterial strains, resulting in more electroactive bacteria containing Pseudomonas, Flavobacterium, Pseudoxanthomonas, and Geobacter constructing the microbial community in M-BTF. [Display omitted] • A novel bioelectrochemical system was designed to enhance the pollutant removal. • The closed circuit produced more biomass and had a clear selectivity for the bacteria. • The anode accelerated mass transfer and improved the metabolic of microorganisms. [ABSTRACT FROM AUTHOR]

Catalytic destruction is an ascendant technology for the abatement of volatile organic compounds (VOCs) originating from solvent-based industrial processes. The varied composition tends to influence each VOC's catalytic behavior in the reaction mixture. We investigated the catalytic destruction of multi-component VOCs including dichloromethane (DCM) and ethyl acetate (EA), as representatives from pharmaceutical waste gases, over co-supported H x PO 4 -RuO x /CeO 2 catalyst. A mutual inhibitory effect relating to concentrations because of competitive adsorption was verified in the binary VOCs oxidation and EA posed a more negative effect on DCM oxidation owing to EA's superior adsorption capacity. Preferential adsorption of EA on acidic sites (H x PO 4 /CeO 2) promoted DCM activation on basic sites (O2−) and the dominating EA oxidation blocked DCM's access to oxidation centers (RuO x /CeO 2), resulting in boosted monochloromethane yield and increased chlorine deposition for DCM oxidation. The impaired redox ability of Ru species owing to chlorine deposition in turn jeopardized deep oxidation of EA and its by-products, leading to increased gaseous by-products such as acetic acid originating from EA pyrolysis. Notably, DCM at low concentration slightly promoted EA conversion at low temperatures with or without water, consistent with the enhanced EA adsorption in co-adsorption analyses. This was mainly due to that DCM impeded the shielding effect of hydrolysate deposition from rapid EA hydrolysis depending on the decreased acidity. Moreover, water benefited EA hydrolysis but decreased CO 2 selectivity while the generated water derived from EA was likely to affect DCM transformation. This work may provide theoretical guidance for the promotion of applied catalysts toward industrial applications. [Display omitted] [ABSTRACT FROM AUTHOR]

Formaldehyde (FA) and acetaldehyde (AA) are known as the two major pollutants used at industrial processes. The BiOI@NH2-MIL-125 (Ti)@Zeolite heterostructures combined with UV-assisted peroxone process were investigated for oxidative degradation of the aldehydes in a continuous waste air stream. Different characterisation methods including XRD, FTIR, FESEM, EDS, EDS elemental mapping, BET, TEM and XPS were used to characterise the photocatalyst. This study focuses on optimising the parameters selected for removal of FA and AA using the one-factor-at-a-time (OFAT) technique. Therefore, the effects of operational parameters: air flow rate, ozone feeding rate, hydrogen peroxide (H2O2) concentration, relative humidity (RH), and initial concentrations on FA and AA removal efficiency were investigated and optimised using the OFAT procedure. The results showed the complete degradation of FA and AA were achieved at optimal conditions (air flow rate: 0.2 L/min, O3 dosage: 0.3 and 0.4 mg/min for FA and AA, respectively, H2O2 concentration: 150 and 200 ppm for FA and AA, respectively, RH of 35%, and an initial pollutant concentration of 5 ppm). In addition, kinetic models revealed that the FA and AA degradation process are fitted with first-order kinetic (R2 = 0.85). Mineralisation analysis revealed that the complete degradation of FA and AA were obtained at CO2 levels of 4.3 and 3.9 ppm, respectively. Overall, it could be concluded that the suggested treatment method has the capability to efficiently eliminate the aldehydes of interest from waste gases. [ABSTRACT FROM AUTHOR]

The conventional aeration method is compulsorily continuous ventilation or aeration at equal intervals, and a uniform aeration rate does not vary during composting. A dynamic on-demand aeration approach based on the diverse oxygen consumption of microorganisms at different composting stages could solve the problems of insufficient oxygen supply or excessive aeration. This study aims to design an aerobic composting system with dynamic aeration, investigate the effects of dynamic aeration on the temperature rise and physicochemical characteristics during the aerobic composting of corn straw and pig manure, and optimise the control parameters of oxygen concentration. Higher temperatures and longer high-temperature durations were achieved under dynamic aeration, thereby accelerating the decomposition of organic compounds. Dynamic aeration effectively reduced the aeration frequency, the convective latent heat and moisture losses, and the power consumption in the middle and later stages of composting. The dynamic aeration regulated according to the oxygen concentration of 14%–17% in the exhaust was optimum. Under the optimal conditions, the period above 50 ℃ lasted 8.5 days, and the highest temperature, organic matter removal, and seed germination index reached 65.82 ℃, 37.59%, and 74.59%, respectively. The power consumption was decreased by 33.58% compared to the traditional intermittent aeration. Dynamic aeration would be a competitive approach for improving aerobic composting characteristics and reducing the power consumption and the hot exhaust gas emissions, especially in the cooling maturation stage, which was of great significance for realising the low-cost production of composting at scale and promoting the blossom of the organic fertiliser industry. [ABSTRACT FROM AUTHOR]

In this comprehensive investigation, the sustainable production and utilization of gas separation membranes derived from coconut water (CW) waste was investigated. The research focuses on the synthesis of bacterial cellulose (BC) and cellulose acetate (CA) membranes from CW, followed by a thorough analysis of their characteristics, including morphology, ATR-FTIR spectroscopy, tensile strength, and chemical composition. The study rigorously evaluates membrane performance, with particular emphasis on CO2/CH4 selectivity under various operational conditions, including pressure, membrane thickness, and number of stages. The application of these membranes in gas separation units was optimized for CO2/CH4 separation performance and eco-efficiency through a multi-stage membrane approach. The findings indicate that in double-stage configurations, CA membranes with a thickness of 0.04 mm, operating at 0.28 MPa, achieve a CO2/CH4 selectivity of 35.52, significantly surpassing single-stage performance (selectivity: 19.72). Furthermore, eco-efficiency analysis reveals optimal performance at 0.04 mm thickness and 0.175 MPa, reaching 3.08 CO2/CH4 selectivity/THB. These results conclusively demonstrate the viability of converting agricultural waste into high-performance gas separation membranes, representing a significant advancement in sustainable membrane technology. This research contributes valuable insights to the field and paves the way for further innovations in eco-friendly membrane production and application. [ABSTRACT FROM AUTHOR]

In this work, a series of BaxMn0.7Cu0.3O3 samples (x: 1, 0.9, 0.8, and 0.7, BxMC) was synthesized, characterized, and used as catalysts for CO oxidation reaction. All formulations were active for CO oxidation in the tested conditions. A correlation between the electrical conductivity, obtained by impedance spectroscopy, and the reducibility of the samples, obtained by H2-TPR, was observed. The Ba0.8Mn0.7Cu0.3O3 composition (B0.8MC) showed the best catalytic performance (comparable to that of the 1% Pt/Al2O3 reference sample) during tests conducted under conditions similar to those found in the exhaust gases of current gasoline engines. The characterization data suggest the simultaneous presence of a high Mn(IV)/Mn(III) surface ratio, oxygen vacancies, and reduced copper species, these two latter being key properties for ensuring a high CO conversion percentage as both are active sites for CO oxidation. The reaction temperature and the reactant atmosphere composition seem to be the most important factors for achieving a good catalytic performance, as they strongly determine the location and stability of the reduced copper species. [ABSTRACT FROM AUTHOR]

The development of materials with high adsorption capacity for capturing CO2 from industrial exhaust gases has proceeded rapidly in recent years. Li4SiO4 has attracted attention due to its low cost, high capture capacity, and good cycling stability for direct high-temperature CO2 capture. Thus far, the CO2 adsorption mechanism of Li4SiO4 is poorly understood, and detailed phase transformations during the CO2 adsorption process are missing. Here, aided by in situ X-ray diffraction and in situ Raman spectroscopy, we find that Li4SiO4 reacts with CO2 to form Li2SiO3 and Li2CO3 in CO2 atmosphere at 973 K, with no detectable involvement of crystalline Li2O during the adsorption process. Moreover, we observe a formation of stepped structures in the Li4SiO4 surface after CO2 adsorption by scanning electron microscopy. To illustrate the formation of stepped structures, we propose a modified double-shell mechanism, suggesting a possible two-dimensional nucleation and growth of Li2CO3. This work provides a deeper understanding of the CO2 adsorption mechanism and paves a way for further optimization of Li4SiO4-based adsorbents. [ABSTRACT FROM AUTHOR]

Micro combustion offers a promising pathway for powering small-scale devices, yet achieving stable flame propagation at this scale remains challenging. Ammonia, a carbon-free fuel, has emerged as a potential candidate, but its intrinsic combustion characteristics pose challenges. Blending ammonia with hydrogen enhances its combustion properties. This study investigates the performance of a hydrogen/ammonia micro combustor, stabilized by both a bluff-body and swirling flows, under various flow parameters and bluff-body configurations. Key findings indicate that increasing the inlet mass flow rate and ammonia-to-hydrogen ratio enhances thermal efficiency and exhaust gas temperatures, albeit at the cost of decreased radiation efficiency. Furthermore, increasing the equivalence ratio diminishes thermal efficiency and reduces emissions, while oxygen enrichment significantly boosts combustion and radiation efficiencies, as well as mean outer wall temperatures, despite a decrease in thermal efficiency. Additionally, the size and half-angle of the bluff-body emerge as critical factors affecting combustion and thermal efficiencies. Larger bluff-bodies enhance combustion and radiation efficiencies, leading to more uniform wall temperatures. On the other hand, emissions decrease with increasing bluff-body size but increase with greater half-angles. These insights hold substantial implications for the design and optimization of micro combustion-based power generators, particularly in the pursuit of minimizing carbon emissions. • A novel bluff-body and swirl-stabilized micro combustor for micropower is proposed. • Effects of flow and structural parameters on thermal performance are examined. • Larger bluff-bodies enhance combustion and radiation efficiencies. • Stoichiometric conditions led to the highest combustion and radiation efficiency. • Oxygen enrichment raises exhaust gas temperature, radiation efficiency, and N O x. [ABSTRACT FROM AUTHOR]

A CO-SCR reaction, capable of simultaneously removing NO and CO from vehicle exhaust gases, has garnered significant attention. PGM (platinum group metal) catalysts are still the preferred choice due to their exceptional catalytic efficiency. However, an in-depth understanding of these catalysts' structure–performance relationship is still lacking. In this study, a series of PGM–CeO2/Al2O3 catalysts were prepared with an identical metal loading. Employing operando infrared spectroscopy, we investigated the evolutions of intermediates and combined relevant characterization techniques with reaction kinetics analysis and DFT simulation calculations to elucidate the nature of the difference in activity. PGM–Al2O3 catalysts produced N2O in the CO + NO reaction, while no significant N2O generation was observed in PGM–CeO2 catalysts. The activity of Pt-based catalysts was notably worse than that of other catalysts due to "CO poisoning". Rh–CeO2 catalysts exhibited optimal reactivity owing to the atomic dispersion of Rh, while some Rh atoms underwent sintering leading to decreased activity after aging. Although Pd nanoparticles suffered an increase in vertical height during aging, moderate adsorptions of CO and NO made the aged Pd–CeO2 catalysts perform superior to others. It is evident that metal dispersion does not exclusively dictate catalytic performance; factors such as the local coordination environment of the metal and the adsorption properties of reactants on the metal play equally crucial roles. [ABSTRACT FROM AUTHOR]

Turbine engines are currently one of the most important and expensive aircraft components. Both for economic and safety reasons, high engine reliability is required. Therefore, sophisticated methods are needed to determine their current condition. Diagnostics of turbine engines allow for the detection of faults before they lead to damage. The article presents methods and results of vibroacoustic diagnostics of a miniature GTM400 jet engine adapted to kerosene and hydrogen fuel supply. During thermal and vibroacoustic tests of engine parameters powered by hydrogen fuel supply, the engine seized up in the initial start-up phase due to improper control and rapid thermal changes in the gas line. The cause of the undesirable technical condition of the engine was a significantly higher temperature of gases (exhaust gases) affecting the working elements of the engine (turbine shaft, rotor, and blades), which consequently led to engine damage. This phenomenon and the results obtained from the unexpected technical condition constitute a valuable premise for considering the issue of proper operation of the turbojet engine during fuel changes, especially following current trends related to the decarbonization of the aviation sector. The obtained research results and the resulting observations and conclusions make it necessary to perform technical analyses and pre-implementation tests each time before allowing the use of a conventional engine if it undergoes the process of reconstruction in terms of using a new fuel (especially if its technical parameters are different from the originally used one). The presented method of conducting tests allows for a detailed determination of the causes of damage to the cooperating elements of the engine structure under the influence of changes in operating parameters. [ABSTRACT FROM AUTHOR]

This article presents a comprehensive examination of the combined catalytic conversion technology for nitrogen oxides (NOx) and volatile organic compounds (VOCs), which are the primary factors contributing to the formation of photochemical smog, ozone, and PM2.5. These pollutants present a significant threat to air quality and human health. The article examines the reaction mechanism and interaction between photocatalytic technology and NH3-SCR catalytic oxidation technology, highlighting the limitations of the existing techniques, including catalyst deactivation, selectivity issues, regeneration methods, and the environmental impacts of catalysts. Furthermore, the article anticipates prospective avenues for research, underscoring the necessity for the development of bifunctional catalysts capable of concurrently transforming NOx and VOCs across a broad temperature spectrum. The review encompasses a multitude of integrated catalytic techniques, including selective catalytic reduction (SCR), photocatalytic oxidation, low-temperature plasma catalytic technology, and biological purification technology. The article highlights the necessity for further research into catalyst design principles, structure–activity relationships, and performance evaluations in real industrial environments. This research is required to develop more efficient, economical, and environmentally friendly waste gas treatment technologies. The article concludes by outlining the importance of collaborative management strategies for VOC and NOx emissions and the potential of combined catalytic conversion technology in achieving these goals. [ABSTRACT FROM AUTHOR]

This study investigates the air oxidation and ozone-enhanced oxidation of zinc sulfite. Zinc sulfite was prepared by reacting pure or industrial zinc oxide with SO2 in water. The oxidation experiments were conducted under constant temperature conditions, with slurry, oxygen, and ozone concentrations in the ranges of 0.5–4%, 10–60%, and 1100–1920 ppm, respectively. The experiments involved determining the zinc ion concentration, sulfite concentration, dissolved oxygen, ozone concentration in the exhaust gas, and total organic carbon value for analysis of the oxidation process. The findings revealed that the mass transfer rate of O2 and/or O3 determined the reaction rate in the main stage of the oxidation process, while ozone affected the non-mass transfer control stage, resulting in an average enhancement of 15% in the oxidation rate. Furthermore, ozone causes organic matter attached to industrial zinc sulfite particles to fall off into the solution, significantly improving the oxidation ratio of industrial zinc sulfite. [ABSTRACT FROM AUTHOR]

Hollow fiber membrane humidifiers are used in mobile proton exchange membrane (PEM) fuel cell systems to humidify the supply air of the fuel cell and thereby to achieve a sufficient level of humidification of the PEM. A hollow fiber humidifier contains a large amount of hollow fiber membrane that transfers water from the moisture-laden exhaust gas of the fuel cell to the dry supply air along a concentration gradient. In this study, the effect of fiber placement on the water transfer inside hollow fiber bundles is investigated in detail using a validated CFD model of a membrane humidifier. To analyze the effects of fiber positioning, 80 simulations using humidifiers with different fiber numbers and placements are carried out and analyzed for two operating points. Two statistical metrics, the wrap-around discrepancy and a distance-based metric called MaxiMin, are used to assess the uniformity and space-filling properties of the fiber placements. Correlations of the uniformity of fiber placement and the water transfer inside hollow fiber bundles are then identified. Furthermore, it is demonstrated that both, the wrap-around discrepancy and the MaxiMin, can be used as optimization criterion for the fiber placement inside humidifiers to maximize water transfer rates. The optimization leads to an average improvement of 5 % in water transfer compared to a median random fiber distribution. [ABSTRACT FROM AUTHOR]

The objective of this study is to investigate the potential of combined pond fly ash (PFA) and flue gas desulfurization gypsum (FGDG) as a partial replacement for cement by mixing them with fine river sand for green mortar development. We studied the physical, mechanical, and microstructural properties of mortars by using techniques such as scanning electron microscopy equipped with energy-dispersive X-ray spectroscopy (SEM-EDXS) and X-ray diffraction (XRD) for chemical component identification of the hydrated phase. These experimental results show that mortar containing pond fly ash, FGDG, and cement concentrations of 5 wt%, 5 wt%, and 90 wt% yields the maximum compressive strength (8.9 MPa) and flexural strength (3.4 MPa) after 28 days. This mortar has 12.6% higher compressive strength and 48% lower shrinkage in comparison with control specimens. A reduction in shrinkage is attributed to the denser structure of the mortar, as the calcium silicate hydrate (C–S–H) gel is found to exist in the SEM image and also identified through XRD studies. It is also concluded that excessive ettringite formation causes expansion in the volume of mortar, voids formation, and results in the reduction of strength. The application of this mortar can be in the internal plaster, bricks, and masonry. [ABSTRACT FROM AUTHOR]

The world is currently grappling with the detrimental effects of escalating pollution stemming from exhaust gases emitted by vehicles, exacerbating environmental degradation and posing severe health risks. To mitigate this crisis, leveraging appropriate technologies capable of curbing emissions is imperative. A recent study undertook a comprehensive assessment, comparing the carbon footprint of various vehicles, considering parameters such as emissions in battery manufacturing and fuel consumption. Employing entropy and TOPSIS methodology, the analysis assigned weights and rankings to these criteria and vehicle alternatives. Results indicated that battery manufacturing emissions carried the most significant weight (81.91%), followed by emissions from fuel consumption (15.99%). Hybrid vehicles emerged as the most favorable alternative, closely followed by biodiesel, exhibiting the lowest carbon emissions including CO, CO2, and UBHC. This study offers invaluable insights for future decision-makers in the transportation sector, facilitating informed choices towards adopting environmentally sustainable vehicles, thereby contributing to a greener and healthier future. [ABSTRACT FROM AUTHOR]

Exhaust Gas Cleaning Systems, i.e., "scrubbers", have been installed on ships as an alternative to low sulfur maritime fuels. The effluent that open-loop systems discharge is a cocktail of low pH seawater with high concentrations of PAHs, metals and particles, and poses concern to the marine environment. Metazooplankton are the first metazoan responders to exogenic pressures, thus understanding their responses to scrubber effluents will provide insights of shipping impacts on higher trophic levels of marine ecosystems. In the present community ecotoxicology study, experimental jars were utilized to examine scrubber effluent effects on the small-size fraction of coastal metazooplankton populations (Thessaloniki Bay, Eastern Mediterranean Sea). Treatments were set up by applying two scenarios: (a) low scrubber effluent content (1% v/v; LS) and (b) high scrubber effluent content in seawater (10% v/v; HS) compared with seawater; Control (C). Overall, a non-significant change in copepod's developmental stages (nauplii) was documented in LS treatments compared to controls (C: 1,179; LS: 988 ind per experimental jar), contrary to the significant effects detected in HS treatments (674 ind per experimental jar). The responses were species-specific, with Oithona responding positively and exhibiting positive growth rates across treatments (C: 0.3; LS: 0.2; HS: 0.2 d−1). Community network analysis revealed greater connectivity of metazooplankton species and groups in the Control and LS treatments compared to HS. Overall, no adverse effects in the 1% scrubber effluent treatments were reported in the plankton copepods community in our community ecotoxicological experiment, complementing the respective results on natural bacterioplankton and phytoplankton communities. [ABSTRACT FROM AUTHOR]

An experimental investigation is carried out on conventional compression ignition engines' combustion, performance, and emission characteristics using Conventional Dual Fuel (CDF) combustion and reactivity-controlled compression ignition (RCCI) combustion strategies. The experiments are performed on a variable-speed production-grade diesel engine converted to a research engine. Comparative combustion analysis shows that RCCI combustion is more stable and shows a consistent ignition delay across all engine speeds. The exhaust gas temperature of RCCI combustion is lower than that of CDF combustion and is in the range of Conventional Diesel Combustion (CDC). CDC shows better brake thermal efficiency (BTE) than CDF and RCCI combustion across all engine speeds, followed by RCCI combustion. The lowest BTE is observed in CDF combustion. Emission results show that RCCI combustion produced significantly lower NOx emissions than CDC at low engine speed without much HC and CO emissions increment. RCCI combustion does not effectively reduce NOx emissions and produces higher HC and CO emissions at high engine speeds. A BTE-NOx trade-off analysis is also carried out, demonstrating the suitability of RCCI combustion at low engine speed. CDC under high engine speed conditions and in the transition region of medium engine speed CDF combustion is more favorable to reduce NOx emission. [ABSTRACT FROM AUTHOR]

Purpose: The objective of this study is to investigate the impact of restorative supply chain practices on sustainability performance in a circular economy (CE). The moderating effect of supply chain managers' perceived professional status on restorative supply chain practices and stakeholder collaboration is also examined. Design/methodology/approach: The theoretical model was developed via the practice-based view, and the model was tested using a sample comprising 142 respondents. WarpPLS 8.0 software was utilized to run the structural equation model. Findings: The analysis shows that restorative supply chain practices result in an intermediate outcome (i.e. stakeholder collaboration), which ultimately improves the sustainability performance of the restorative supply chain. Interestingly, the perceived professional status of supply chain managers acts as a moderate-level mediator in the relationship between restorative supply chain practices in a CE and the sustainability performance of the restorative supply chain in a CE. Practical implications: Collaboration with stakeholders fosters enhanced communication, cooperation and shared responsibility, thereby creating a socially inclusive and cooperative environment within the restorative supply chain. Improving supply chain sustainability performance supports broader environmental goals, including reducing greenhouse gas emissions and waste and conserving natural resources. Recognizing the perceived professional status of supply chain managers underscores the need to empower them and acknowledge their strategic role in driving sustainability within the organization. Companies can contribute to a more sustainable business environment by adopting restorative practices in the supply chain and addressing the social impacts. Originality/value: The unique contribution of the findings of this study lies in the examination of the relationship between restorative supply chain practices, stakeholder collaboration, perceived status of supply chain managers and sustainability performance in the context of the CE. The findings imply that restorative supply chain practices positively impact stakeholder collaboration, which in turn improves supply chain sustainability performance. In addition, the study highlights the moderating role of the perceived status of supply chain managers and underscores their influence on strengthening restorative practices and stakeholder collaboration. This study provides valuable insights into the dynamics and mechanisms driving sustainability performance in the context of restorative supply chains operating within a CE. [ABSTRACT FROM AUTHOR]

The sudden surge phenomenon in an axial compressor represents one of the most critical issues that can confront a turbojet engine. This phenomenon primarily arises from the engine ingesting hot exhaust gases from weaponry systems, particularly in military aircraft, potentially leading to engine failure. This study delves into the impact of hot gas ingestion on compressor stability and compares a range of effective methods to prevent surge in such cases which are: (1) air bleed from the compressor, (2) fuel cut-off, (3) gas cooling through water injection at the air inlet. The R29-300 twin-spool turbojet engine was chosen for computational experiments due to the availability of the necessary digital information for mathematical modelling of this engine. It is a two-shaft turbojet engine consisting of a low-pressure compressor (5 stages), a high-pressure compressor (6 stages), an annular combustion chamber, a high-pressure turbine (two stages), and a low-pressure turbine (one stage). The results showed that introducing gases with a heating rate of up to 5000 Kelvin per second causes the low-pressure compressor to exit its stable operating regime and the engine to stall. The effect on the high-pressure compressor was minimal and did not exceed the stability limits, therefore the focus of the procedures was on the low-pressure compressor. The results also showed that both methods 1 and 2 are effective in preventing surge within an acceptable stability range, but they have several drawbacks, including a decrease in engine thrust and efficiency. On the other hand, the water injection method eliminates the root cause of surge by cooling the incoming gases and maintains engine stability. The amount of water required for this process is relatively small and can be carried on aircraft without a significant impact on weight and volume. [ABSTRACT FROM AUTHOR]

Due to the increasing concern on how to manage wastes and ensure environmental safety across the globe, a new tool that assists in the monitoring of methane, humidity, and temperature in the landfill using internet of things (IoT) has been created. This system uses ESP32 microcontroller and MQ-4 and DHT-22 sensors to measure environmental conditions at three different spots in a landfill. The samples of data are collected at three times a day, that is, in the morning at 7:00 am, at midday at 12:00 pm and in the evening at 5:00 pm and the data is transmitted to an online sheet where the public can access it in real time hence increasing transparency in the management of wastes. The tool shows a very good precision and effectiveness and the parameters are 94. 6% data integrity over three months testing period. The first findings show that the mean methane concentration is the highest at midday, which is related to the temperature and underlines the role of temperature in the methane emission process. The presented IoT based monitoring system also enhances the accuracy and efficiency in the monitoring of landfill gas and at the same time reduces the intervention of human effort and increases the capability to make prompt adjustments to changes in the environment. Used as an instrument for obtaining accurate and easily understandable data, it is hoped that this tool will in some way help to enhance global environmental health and safety standards, and help pave a way for methane storage for renewable energy purposes. [ABSTRACT FROM AUTHOR]

Proton exchange membrane (PEM) fuel cells are increasingly recognized as a viable clean energy option in mobility, due to their high efficiency and minimal greenhouse gas emissions. A significant challenge in enhancing PEM fuel cell systems lies in improving the efficiency of the air processing subsystem (APS). Despite recent progress, further optimization is imperative, particularly in addressing costs, service life, efficiency, and dynamic behaviour. This study presents an innovative approach to cathode exhaust gas recirculation (CEGR) in the fuel cell's air supply system, enhancing both lifetime and efficiency by optimizing idling and freeze-start behaviours, thus enhancing the operational range. The system recirculates oxygen-depleted humid exhaust gas to the fuel cell stack, facilitated by components including a control valve, water separator, collection tank, and diaphragm pump. Simulation models provide detailed correlations between the gas composition of recirculated exhaust gas, oxygen stoichiometry, and cell voltage. Based on these insights, a control system for freeze starts and idling is developed. Simulation findings highlight the potential of the exhaust gas recirculation system to save up to 83 % hydrogen and extend service life during idle power through targeted cell voltage reduction. Furthermore, additional heat generation enables freeze starts up to 4.6 times faster at temperatures below −30 °C. [Display omitted] • A cathode exhaust gas recirculation (CEGR) system for a PEM fuel cell system was designed. • The influence of CEGR on gas composition and cell voltage was determined by simulation. • CEGR's potential for faster freeze starts, greater hydrogen efficiency, and longer lifetime in idling mode was demonstrated. • An operating strategy and a control concept for CEGR operation were developed. • Risks associated with CEGR were identified through a risk analysis. [ABSTRACT FROM AUTHOR]

One of the main causes of air pollution, particularly in large cities, is vehicles due to it continued use of hydrocarbon fuels. The understanding of nonlinear interactions of vehicle parameters uncovers more realistic relationships for enhancing formulation of strategies to address vehicle-related pollution. Thus, the study aims to evaluate the interaction and quadratic effect of vehicle parameters on Hydrocarbon (HC), Carbon dioxide (CO2), Carbon monoxide (CO), and Nitrogen oxide (NOx) emissions. The SV-5Q Vehicle Exhaust Gas Analyzer was used to collect emission concentrations data from one thousand and two (1002) light-duty petrol vehicles at three (3) government-accredited vehicle inspection sites in Accra, Ghana. Pollution control devices, maintenance frequency, and vehicle age were also collected. The linear regression analysis revealed that vehicle age showed a positive linear relationship with CO emissions. Maintenance frequency, on the other hand, demonstrated a negative linear relationship with both CO and HC emissions. The interaction between vehicle age and maintenance frequency positively impacted CO and HC emissions, while the interaction between vehicle age and emission technology had a negative effect on CO. Additionally, the combined effect of frequency of maintenance and emission technology significantly reduced CO emissions but increased HC emissions. Notably, the quadratic effect of vehicle age positively influenced CO emissions. Similarly, CO, HC, and NOx emissions were positively correlated with the squared effect of emission technology. Stricter emissions standards, encouraging frequent maintenance and testing of vehicular exhaust emissions, and doing away with over-aged vehicles are recommended to control and reduce vehicular exhaust emissions. [ABSTRACT FROM AUTHOR]

Ce doped MnO2/γ-Al2O3 catalysts are prepared and analysed by BET, XRD and SEM in this paper. The degradation of chlorobenzene (CB) by a synergistic system of catalyst and DC corona discharge is further investigated to examine the effects of discharge voltage on CB removal efficiency, CO2 selectivity and by-product O3 generation. The results show that the voltage is proportional to the removal efficiency of CB and the selectivity of CO2. At a voltage of 40 kV, the CB removal efficiency and CO2 selectivity are 88% and 75%, respectively. O3 is more likely to decompose into active oxygen atoms with Ce doped MnO2/γ-Al2O3 type catalyst, and its O3 emission is about 50–250 ppm lower than that of NTP alone. In addition to studying the effect of CB treatment, the decomposition mechanism of CB is also discussed by examining the exhaust gas by GC-MS. [ABSTRACT FROM AUTHOR]

Recirculation of the unconsumed anodic gas present in the exhaust stream of Proton Exchange Membrane Fuel Cells (PEMFC) represents a solution frequently used for improving the utilization efficiency of hydrogen. The design of an anodic recirculation system (ARS) can include an ejector that carries the recuperated hydrogen stream directly into the fuel supply line. Compared to pumps, ejectors have no moving parts and do not require power to work, thus increasing the overall efficiency of the cell. On the other hand, they are sensitive to load changes and need an attentive design process. Nozzle diameter and position, convergent and divergent angle, the ratio between nozzle and mixing chamber diameters are several parameters that are usually optimized by trial and error. In this work the development and validation of a 3D CFD model for an ejector to be used on a 5000 W PEMFC was performed. In addition, three new geometries of ejectors to be coupled with 3000 W, 1000 W and 300 W fuel cells were designed. Finally, the scalability and convenience of an ejector for different static power requests were assessed. • Validation of a 3D CFD model for and ejector used in a PEMFC recirculation system. • Definition of scaled versions of the original ejector using optimal "rule of thumb" ratio from literature. • Discussion on feasibility of the prototyping and mass production of this family of ejector with additive manufacturing. [ABSTRACT FROM AUTHOR]

[Display omitted] • Landfill quarters and composting facilities identified as high CH 4 emission zones. • Atmospheric 13C-depleted CH 4 indicates contamination from emission hotspots. • δ13C-CH 4 signatures identify no predominant CH 4 production pathway. • δ13C-DIC of leachates is linked to the initial methanogenesis phase of active quarter. • Difference in traces concerns NO 2 , SO 2 , chlorocarbons, alkanes, benzene and alcohols. Landfill operations and waste processing facilities are important and highly heterogeneous sources of both greenhouse gases (GHGs) and non-GHG air pollutants in the atmosphere. This arises the need for detailed apportionment of waste sources in order to locate and subsequently reduce emissions from landfills. Here, a time series of in situ measurements of atmospheric trace gases and spatial allocation of specific emission source types under different processing phases and environmental conditions were conducted in and in the surroundings of a Municipal Solid Waste Treatment Plant (MSWTP) in south-western Poland. Results revealed that several individual GHG sources dominated across the waste processing facility and that GHGs concentrations displayed spatial seasonality. An increase in the ground-level CH 4 concentrations, from ∼ 30.3 to 56.3 ppmv, was observed close (∼5 – 10 m) to the major emission sources within the MSWTP. While hotspot areas generally yielded elevated CH 4 concentrations near the soil surface, these were relatively low (2.4 to 8.9 ppmv) along the facility's fence line. The study of the corresponding δ13C delineated the extent of dispersion plumes downwind emission hotspots, characterized by a 13C depletion (around 4.0 ‰) in the atmospheric CH 4 and CO 2. For CH 4 , emissions were isotopically discriminated between the extraction wells at active quarters/cells (δ13C = –58.3 ± 1.1 ‰) and biogas produced in the biological waste treatment installation (δ13C = –62.7 ± 0.7 ‰). Most of the trace compounds (non-methane hydrocarbons, halocarbons, oxygen-bearing organic gases, ketones, nitrogenous and sulphurous gases, and other admixture compounds) detected at the ground surface were linked to the CH 4 - and CO 2 -rich spots. Despite the relatively high variability in the concentrations of organic and inorganic compounds observed at the MSWTP active zones, our results suggest that they do not have a meaningful impact on the surrounding air quality. [ABSTRACT FROM AUTHOR]

This article presents a method for identifying the cause of damage to a rotary air preheater on one of the fluidized bed boilers operating in a power plant. The bearing in question operates under harsh conditions with the exhaust gas temperature reaching 287 °C and causing its casing to heat up intensively. It is therefore important to ensure that the bearing is constantly cooled by water, which lowers the operating temperature and thus extends its service life. Unfortunately, after a short period of operation, the upper double-row spherical roller bearing was damaged, and the tests presented in the assessment method helped to determine the cause of damage to its casing. [ABSTRACT FROM AUTHOR]

Exhaust gas recirculation (EGR) systems, in addition to catalytic reactors, are now widely used in reciprocating internal combustion engines to reduce oxides of nitrogen (NOx) in the exhaust gases. They are characterized by the fact that part of the exhaust gas from the exhaust manifold is recycled and directed to the intake manifold through a special valve. This valve, depending on the current engine load and velocity, doses an appropriate amount of exhaust gas which, with each new charge, is fed to the individual engine cylinders. In addition, the positioning of the valve has a significant effect on the formation of nitrogen oxides in the exhaust gas from individual engine cylinders, which is due to the uneven distribution of exhaust gas into the intake manifold channels. Tests were carried out on a power unit equipped with a symmetrical intake manifold with a centrally located EGR valve. The article presents the results of tests on a system in which each cylinder was supplied with a separate EGR valve. This solution made it possible to charge each cylinder with the same mass of recirculated exhaust gas, which was dependent on engine velocity and load. The exhaust nitrogen oxides emissions were measured for the originally manufactured system and compared with the multi-valve system. The results confirmed the need for individual selection of the dose of recirculated exhaust gas for particular cylinders, as the multi-valve system equalized the levels of nitrogen oxides emissions in the exhaust gases coming from individual cylinders of the internal combustion engine. [ABSTRACT FROM AUTHOR]

According to the Bureau of National Statistics of the Republic of Kazakhstan, by the end of 2023, approximately 120 million tons of municipal solid waste (MSW) had been generated across over 3200 landfills in the country. About 4.5 million tons are generated annually, of which only about 15% are recycled. The accumulation of both unsorted and sorted waste poses significant environmental risks, primarily through the generation of methane, a greenhouse gas that is 28 times more dangerous than carbon dioxide in contributing to the planet's greenhouse effect over a century and 84 times more effective over a 20-year timeframe. The objective of this research is to examine the physicochemical composition, as well as the physical and thermal-chemical properties, of municipal solid waste from six cities in Kazakhstan: Astana, Almaty, Shymkent, Aktobe, Karaganda, and Ust-Kamenogorsk. Unlike existing studies, this study has a uniform waste sample, which includes the complete emptying of dozens of containers from different areas of the cities under consideration. Thus, the average composition of solid waste across the cities was maintained. Analysis of the physicochemical composition was conducted for both unsorted and sorted municipal solid waste from all cities, determining the total and analytical moisture content, ash content, and volatile matter, as well as the higher and lower calorific values. The calorific value of unsorted waste by city was as follows, in kJ/kg: Astana,8850.37; Almaty, 9244.57; Atobe, 9596.41; Shymkent, 9425.48; Karaganda, 8902.8; Ust-Kamenogorsk, 9669.07. The calorific value of sorted waste was as follows, in kJ/kg: Astana, 11,922.79; Almaty, 11,692.31; Atobe, 11,913.13; Shymkent, 12,494.38; Karaganda, 11,671.92; Ust-Kamenogorsk, 12,462.52. The efficiency of sorting was estimated as the first stage of MSW processing. The efficiency factor of the manual sorting process in practice was 0.4–0.8. The results obtained enable the evaluation of technologies for the effective management of municipal solid waste and facilitate experimental investigations into semi-industrial pyrolysis, combustion, plasma processing, and composting facilities. [ABSTRACT FROM AUTHOR]

Air pollutant emissions from the agricultural sector are among the most critical issues affecting human health and the environment. This sector releases a complex mixture of biological, microbial, and inorganic contaminants into the air from land preparation, crop production, fertilization, harvesting, biomass burning, machinery use, livestock production, manure management, waste management, and deforestation. This article aims to identify the evolution and global research trends related to air contaminant emissions, specifically from the agricultural sector. This study systematically analyzed the knowledge map derived from 4016 scientific publications from 1990 to 2023. From an evolutionary perspective, the bibliometric and networking analysis revealed a consistent increase in scientific publications over the past 34 years, with the contribution of 117 countries, more than 1600 authors, and 1300 journals. Additionally, it sheds light on the most studied pollutants, measurement techniques, and modeling employed to comprehend and mitigate the impact of these pollutants on yield, human health, biodiversity, and climate change. Furthermore, the research facilitates the identification of emerging air pollutants considering agricultural activities such as crop production, waste crop management, livestock production, manure management, deforestation, and land change use. These findings underscore the evolution of the research, identifying the main topics of interest, the emerging topics, and the future of research on air pollutant emissions. [ABSTRACT FROM AUTHOR]

Copyright of World Nuclear Geoscience is the property of World Nuclear Geoscience Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Addressing climate change demands, energy security and resilience has necessitated replacing conventional fossil-based fuels with zero and carbon-neutral fuels/energy carriers. The most immediate solution is the partial and progressive substitution of conventional fuels in transportation. The effects of partially substituting gasoline with ammonia/hydrogen (NH 3 /H 2) mixtures in a spark ignition (SI) engine are investigated in this paper. The utilization of NH 3 /H 2 mixtures is a promising avenue of research since they can be produced from on-board NH 3 reforming, utilising heat energy that is recovered from hot exhaust gases. Experimental results indicate that adding NH 3 /H 2 enabled stable engine operation at lean conditions (λ = 1.4), resulting in reduced carbon-based emissions due to the non-carbon nature of NH 3 /H 2. Utilising an integrated approach that combined a hemispherical flame geometry model with a thermodynamic model, has revealed that the introduction of NH 3 /H 2 significantly enhanced the combustion speed during the initial phase and further improved combustion efficiency. However, nitrogen-based emissions such as NO and NO 2 increased. This work also assessed the performance of a conventional three-way catalyst (TWC) and a double-function ammonia slip catalyst (ASC) in mitigating emissions. The TWC effectively controlled carbon-based emissions and NO under stoichiometric conditions but exhibited reduced efficiency under lean conditions, especially with NH 3 present. The ASC demonstrated high NH 3 conversion efficiency even at low temperatures, making it suitable for engine start-up and warm-up phases. Under steady-state conditions with artificially increased NH 3 /NO X ratios, a significant reduction in NOx emission was achieved with the ASC. However, high NH 3 /NO X ratios increased nitrous oxide (N 2 O) formation and NH 3 slip. • A combined NH 3 /H 2 combustion study was carried out with a prototype catalyst aftertreatment system. • NH 3 /H 2 blend in gasoline enables lean combustion but raises NO X emissions. • Combustion models show H 2 boosts initial phase burn rates. • TWC lacks N-based abatement capacity in terms of lean and NH 3 presence. • ASC efficiency increases with temperature but worsens with decreasing NH 3 /NO X ratio. [ABSTRACT FROM AUTHOR]

In this article, on the basis of world experience in the field of handling tritium-containing media and on the basis of our own experimental data, a scheme of the tritium cycle system for a tokamak with reactor technologies is proposed. When calculating the characteristics of the tokamak tritium cycle system, it was assumed that the total volume of tritium in the facility is 20 g, and 0.1 g of tritium is consumed per pulse. The proposed scheme provides a complete recycling of tritium and consists of a subsystem for the sorption storage of deuterium and tritium on intermetallic compounds based on zirconium; a subsystem for the chemical purification of the exhaust gas mixture from the toroidal chamber of the tokamak trapping nitrogen, oxygen and carbon ions; a subsystem for the membrane separation of hydrogen isotopes from the gas mixtures; subsystems for the separation of hydrogen isotopes by thermal diffusion; subsystems for the purification of waste process streams by the method of phase isotope exchange, which provides for the preliminary catalytic oxidation of hydrogen isotopes to water; and a subsystem for the concentration of tritium-containing water by the method of chemical isotope exchange in the "water–hydrogen" system. Requirements are provided and analytical and radiometric equipment is proposed to ensure control of the necessary parameters and reliable protection of personnel, the public, and the environment from the effects of tritium. [ABSTRACT FROM AUTHOR]

Background Lowering fresh gas flow (FGF) can help decrease the carbon footprint of the operating room as FGF levels act as an indirect measure of anesthetic gas waste. Objective The aim of this quality improvement project was to reduce clinician FGF during general anesthesia with clinical decision support (CDS) tools within the electronic health record (EHR) at a single institution. Methods A non-interruptive alert to reduce FGF was coded into the anesthesia intraoperative EHR workspace to alert whenever the 10-minute average FGF exceeded 1 L/min. It was targeted at anesthesia residents, attendings, and certified registered nurse anesthetists at a single US large academic level 1 trauma center. The number of general anesthesia cases with a target FGF of ≤2 L/min and the amount of sevoflurane (L/hr) was tracked on an individual and institutional basis. Results Following CDS implementation from July 2023 through July 2024, 2677 of 4573 (58.5%) had a mean FGF ≤2 L/min, demonstrating a 116.7% increase from our institution's baseline of 27.0% (1200 of 4446 cases) from July 2022 to June 2023, corresponding to a sevoflurane usage reduction of 36.7%. Conclusions Implementing a non-interruptive alert in the EHR altered institution-level behaviors to reduce environmentally harmful anesthetic gas emissions. [ABSTRACT FROM AUTHOR]

Integrating electrolyzers within existing reciprocating engine power plants offers a promising solution for enhancing sustainability and operational efficiency. This research develops thermodynamic models within the IPSEpro platform to simulate current conditions and the benefits of retrofitting power plants to oxy-fuel combustion. The results indicate a reduction in water consumption by 19%, from 9.00 to 7.31 kg per kg of hydrogen produced. The concentration of CO 2 in the engine exhaust gases increased significantly, from 8%w to 75%w. This integration enables the generation of electricity with zero operational CO 2 emissions, utilizing existing hardware from old backup power plants and thereby extending its operational life. These findings underscore the potential for significant environmental and economic benefits through the proposed integration of electrolyzers and existing power plants. • Novel integration of electrolyzer and oxy-fuel technologies in old power plants. • Enhanced electrolyzer efficiency achieved with existing engine hardware. • Improved electrolyzer efficiency obtained by reducing water consumption by 19%. • CO2 concentration increased in exhaust gas from 8%w to 75%w, aiding carbon capture. • Electricity generated with zero operational CO2 emissions, extending power plant life. [ABSTRACT FROM AUTHOR]

A large amount of vegetable waste (around 931 million tons in the world) is generated from the kitchen of food eateries per year. The improper disposal of this organic waste may lead to serious health and environmental issues. If this waste is dumped on open ground, it decomposes anaerobically which leads to emission of greenhouse gases mainly methane which is 28 times more potent for the environment than carbon dioxide. So, development of reliable, effective and environment friendly solution for this problem is a need of time. In the present study, potent bacterial isolates were obtained from different sources such as biogas slurry and soil samples, followed by characterization these isolates were tested for their efficiency to degrade vegetable waste. Finally, the selected screened isolates were used for production of bio compost. The efficiency of produced compost was tested against selected fenugreek plant in pot assay. Three cellulose degraders were isolated from selected biogas slurry and soil samples, on different media such as carboxy methyl cellulose agar, cellulose Congo red agar and Congo red agar containing Whatman filter paper. Isolates have shown effective degradation of vegetable waste within 10 days and produced organic compost prove to be effective for stimulating growth of fenugreek plant. The vegetable waste degraded by using micro-organisms in the present study can not only be used to improve crop yield but also help in reduction of greenhouse gases. [ABSTRACT FROM AUTHOR]

The accumulation of anesthetic gas residues in surgery units can pose health risks to healthcare professionals, highlighting the need to establish effective protection measures. This study evaluated waste anesthetic gas levels in a local health unit in northern Portugal to identify high-exposure areas during surgeries using general anesthesia. Measurements of desflurane, sevoflurane, carbon dioxide, air temperature, and relative humidity were taken during 20 surgeries carried out over approximately six months. The results showed that the thermal conditions were not adequately controlled, particularly the relative humidity levels. The detected WAG concentrations fluctuated across different locations, with concerning peaks being detected in specific settings. Desflurane levels reached 8.79 ppm in the general surgery room (GSR) and averaged 3.13 ppm in the recovery room (RR), while the sevoflurane levels averaged 2.06 ppm in the RR. High concentrations exceeding the recommendations of the U.S. National Institute for Occupational Safety and Health (NIOSH) were notably observed after endotracheal tube removal. In short surgeries, anesthetic gas levels exceeded safety limits, while long surgeries caused peaks in sevoflurane levels. Longer surgeries and higher occupancy were significantly linked to increased levels of WAG and carbon dioxide, emphasizing the need to improve ventilation and environmental controls to safeguard healthcare professionals. [ABSTRACT FROM AUTHOR]

The first measures to reduce the environmental harm from volatile anaesthetics are implementation of minimal fresh gas flow strategies and avoidance of desflurane. Although anaesthetic waste gas capture systems generally exert high capturing efficiencies, only about half of volatile anaesthetics used in the operating room are accessible for capture. Industry-sponsored reports promise a reduction of the global warming potential by both incineration and recycling of captured volatile anaesthetics. However, independent high-quality peer-reviewed studies are needed to confirm these findings. [ABSTRACT FROM AUTHOR]

Interest in passive flow filter systems to remove sevoflurane from anaesthetic machine exhaust have increased recently to mitigate the environmental impact of volatile anaesthetics. These filter systems consist of chemically activated carbon, with limited evidence on their performance characteristics. We hypothesised that their efficiency depends on filter material. Binding capacity was tested for three carbon filter materials (CONTRAfluran®, FlurAbsorb®, and Anaesthetic Agent Filter AAF633). Adsorption efficiency and resistive pressure were determined during simulated ventilation at different stages of filter saturation and fresh gas flow. In addition, sevoflurane concentration in filtered gas was measured at randomly selected anaesthesia workstations. Sevoflurane concentration in filtered gas exceeded 10 ppm when saturated with 184 ml sevoflurane each for CONTRAfluran and FlurAbsorb and 276 ml for AAF633. During simulated ventilation, sevoflurane concentration >10 ppm passed through CONTRAfluran and AAF633 at fresh gas flow 10 L min−1 only at maximum saturation, but through FlurAbsorb at all stages of saturation. The resistance pressure of all filters was negligible during simulated ventilation, but increased up to 5.2 (0.2) cm H 2 O during simulated coughing. At two of seven anaesthesia workstations, sevoflurane concentration in filtered exhaust gas was >10 ppm. Depending on the filter material and saturation, the likelihood of sevoflurane passing through passive flow carbon filters depends on the filter material and fresh gas flow. Combining the filter systems with anaesthetic gas scavenging systems could protect from pollution of ambient air with sevoflurane. [ABSTRACT FROM AUTHOR]

Anaesthesia contributes substantially to the environmental impact of healthcare. To reduce the ecological footprint of anaesthesia, a set of sustainability interventions was implemented in the University Hospital Zurich, Switzerland. This study evaluates the environmental and economic implications of these interventions. This was a single-centre retrospective observational study. We analysed the environmental impact and financial implications of changes in sevoflurane, desflurane, propofol, and plastic consumption over 2 yr (April 2021 to March 2023). The study included pre-implementation, implementation, and post-implementation phases. After implementation of sustainability measures, desflurane use was eliminated, there was a decrease in the consumption of sevoflurane from a median (inter-quartile range) of 25 (14–39) ml per case to 11 (6–22) ml per case (P <0.0001). Propofol consumption increased from 250 (150–721) mg per case to 743 (370–1284) mg per case (P <0.0001). Use of plastics changed: in the first quarter analysed, two or more infusion syringes were used in 62% of cases, compared with 74% of cases in the last quarter (P <0.0001). Two or more infusion lines were used in 58% of cases in the first quarter analysed, compared with 68% of cases in the last quarter (P <0.0001). This resulted in an 81% reduction in overall environmental impact from 3 (0–7) to 1 (0–3) CO 2 equivalents in kg per case (P <0.0001). The costs during the final study phase were 11% lower compared with those in the initial phase: from 25 (13–41) to 21 (14–31) CHF (Swiss francs) per case (P <0.0001). Implementing sustainable anaesthesia interventions can significantly reduce the environmental impact and cost of anaesthesia. [ABSTRACT FROM AUTHOR]

Fast detection and correct diagnosis of any engine condition changes are essential elements of safety and environmental protection. Many diagnostic algorithms significantly improve the detection of malfunctions. Studies on diagnostic methods are rarely reported and even less implemented in the marine engine industry. To fill this gap, this paper presents the Support Vector Data Description (SVDD) method as applied to the fault detection of the fuel delivery system of a two-stroke marine engine. The selected diagnostic data is the exhaust gas composition, with four components considered: oxygen, carbon oxide, nitric oxide, and carbon dioxide. With these diagnostics, the method distinguishes eight different engine faults from the efficient state. The manuscript presents in detail the methodology for applying the SVDD method in a marine engine. The method of obtaining diagnostic data and its scaling is described. The method of training and validating the algorithm is also presented, along with ready-made algorithms for use. The 100% accuracy of the proposed fault detection method. Based on the obtained results, the proposed fault detection method is promising for a simple application. Moreover, generalised algorithms that may be adapted to different technical solutions are also presented. Highlights SVDD was used for marine engine fault detection from exhaust gas composition Laboratory measurements were carried out on the two-stroke diesel engine The proposed algorithm detected the considered faults with 100% accuracy A generalised algorithm for adapting other complex technical objects was proposed [ABSTRACT FROM AUTHOR]

Objective The aim is to study the application of calcium-based dry desulfurizer in the field of flue gas desulfurization, and give full play to the advantages of low cost, good desulfurization performance and environmental friendliness of calcium-based desulfurizer, so as to achieve the up-to-standard emission of SO2 in flue gas. Methods The physical and chemical properties of the prepared calcium-based desulfurizer were characterized by XRD, BET, FTIR and XPS. Additionally, simulating sulfur-containing waste gas, the effects of SO2 content, reaction temperature, O2 content and volume space velocity on the desulfurization performance of calciumbased dry desulfurizer were investigated by a fixed bed reactor. Results The prepared calcium-based desulfurizer demonstrated effective desulfurization, and its optimum operating temperature range was 220-300 ℃, which was suitable for the case that the volume fraction of SO2 in flue gas did not exceed 0.4%. The increase of O2 content produced new active sites for adsorption, which could promote desulfurization process. When the volume space velocity was in the range of 500-2 000 h−1, the sulfur capacity did not change much. Conclusions The application of calcium-based dry desulfurizer in the field of flue gas desulfurization has high efficiency and stability, which can provide reference for its wide application in the industrial field. [ABSTRACT FROM AUTHOR]

A diesel particulate filter (DPF) is commonly used to trap particulate matter (PM). The collapse and sintering of carbon and ash deposits during exhaust gas flow and DPF regeneration frequently result in the formation of ash bridges, which are buildups of ash and PM that clog the filter channels. To investigate the impact of an ash bridge formed by accumulated ash on the pressure drop and PM trapping characteristics of asymmetric DPFs, an asymmetric DPF channel with an ash bridge was constructed. The analysis employed computational fluid dynamics to examine how the ash bridge affects the pressure drop and PM trapping characteristics in an asymmetric DPF. This study reveals that the asymmetric DPF design effectively enhances the ash-holding capacity, thereby mitigating the risk of channel blockage. The presence of ash bridges in DPF channels has a more substantial impact on the pressure drop through radial congestion than through axial congestion. The application of asymmetric thin-wall DPFs can counteract the increase in exhaust backpressure caused by ash bridges. An ash bridge located in the middle of a DPF channel intensifies the uneven deposition of PM. However, implementing an asymmetric DPF structure enhances the uniformity of PM deposition. [ABSTRACT FROM AUTHOR]

Based on the self-developed hydraulic variable valve mechanism of four-cylinder engine, this paper proposes a variable displacement valve control strategy based on the VOC-CDA mode of electro-hydraulic. The variation rules of in-cylinder pressure, oxygen mass fraction in exhaust gas, torque fluctuation and other parameters in the process of cylinder deactivation cycle and working mode conversion are analyzed, and the control parameters of inlet and exhaust valves at the best cylinder deactivation time are optimized. The energy saving mechanism of variable displacement technology is analyzed from the aspects of indicated thermal efficiency, mechanical efficiency and effective thermal efficiency. Based on the optimal intake and exhaust valve closing time, the engine can improve the fuel economy by 8.7% at medium and small loads. It provides a certain design reference for the development of variable displacement engine based on hydraulic variable valve mechanism. [ABSTRACT FROM AUTHOR]

Odor emission has become a major issue in waste transfer stations. Hydrogen sulfide, methyl mercaptan (MM), and dimethyl disulfide (DMDS) are the main odorous gases. They have a low odor threshold and are difficult to remove. In this study, pine bark biochar was produced and modified with metal ions, including Ni2+, Ti2+, Mn2+, Zn2+, Mg2+, and Cu2+. It was then used for the removal of hydrogen sulfide, methyl mercaptan, and dimethyl disulfide. Among all modifications, the Cu2+ modified biochar showed the best sorption capacity, and the maximum sorption amounts were 20.50 mg/g for H2S, 36.50 mg/g for MM, and 57.98 mg/g for DMDS. To understand the adsorption, BET, SEM, and XPS of the original and modified biochar were performed. This illustrated that modification with Cu2+ increased the surface area and porosity, thus enhancing the adsorption capacity. In the alkaline absorption study, it was found that the removal of the three odor gases increased with the pH increase. Based on the results, a combined process called absorption–adsorption was established to treat the odor gas generated in a local waste transfer station. Thirty-one gas components were detected in the odor gas of the waste transfer station. The process proceeded for 30 days, and these gas components were not found in the effluent during treatment. Regarding H2S, MM, and DMDS, they were not detected even after 90 days. This indicates the high adsorption capacity of the modified biochar toward the three odor gases. In addition, the process is simple and easy to operate. This suggests that it is suitable for treating odor in places where there is no technician, and the odor needs efficient treatment. The study provides a feasible alternative for domestic waste transfer stations to control the odor problem. [ABSTRACT FROM AUTHOR]

In this work, a DC-transferred arc plasma reactor was used to investigate the influence of operating parameters on the process of gas production from sewage sludge treatment. By varying the operating temperature, feedstock feed rate and exhaust gas flow, the study aims to elucidate the physicochemical mechanisms during plasma treatment. The sewage sludge from the municipal wastewater treatment plant has an ash content of 40.5%, consisting mainly of Si, Al, Fe and Ca (>75%), and a complex organic fraction containing carbonyls, amines and amides. At a constant mass of feedstock (without feed rate), the gas produced by the plasma treatment was obtained with a maximum syngas fraction of 86% and a heating value of 10,000 kJ/m3, while the process operated at a constant sludge feed rate of 300 g/min increased the volumetric fraction of the syngas to 95% and the heating value to 12,000 kJ/m3. [ABSTRACT FROM AUTHOR]

In this article, an idea has been presented that utilizes the heat produced from the petroleum gas burning accompanying the process of oil extraction to enhance the solar chimney performance. The simulation software tool ANSYS Fluent 2020R1 was used to know the possibility of exploiting this waste energy of gas and combining it with a solar chimney. Seven gas channel configurations were tested on the solar chimney to determine which can produce the most electricity. The simulation results showed that this idea could be exploited to produce higher electric energy, and the efficiency of the solar chimney was increased so that the electric energy production process continues for 24 hours instead of production during the sunshine period only. Different designs were considered for the channels inside the solar collector. Case1 and Case2 were meant for validation purposes only. Good agreement was achieved with the previous research with a maximum error of 2%. The results showed that the circular design of the two-ring burner was the best choice which gave the optimum electric power from the system of about 121.1 kW. It was noted that the circular design of the two-ring burner achieved the highest thermal efficiency, which amounted to 0.523%. [ABSTRACT FROM AUTHOR]

To facilitate the integration of a rotating detonation combustor (RDC) in a turbomachine, adding an ejector downstream of the combustor may be a viable option. The present work examines the performance of an ejector configuration under unsteady inflow conditions representative of an RDC exhaust, using a Large-Eddy Simulation. The RDC exhaust gas is generated at the nozzle exit of the ejector by an adequate choice of inlet axial fluctuation amplitude and frequency. The results along the jet centerline showed that the ejector flow remains in the low supersonic regime before passing through a secondary shock located at the constant-area mixing chamber exit. Mixing between the two flows begins immediately at the confluence and terminates slightly upstream of the secondary shock. The consideration of a theoretical thermodynamic cycle with the calculated ejector revealed that the ejector presence increases specific fuel consumption with respect to a reference cycle without an ejector installed. Entropy generation analysis showed that losses associated with thermal conduction have the most significant impact, followed by viscous dissipation losses. Both originate primarily in the shear layer between the RDC exhaust and the secondary flow. The flow characteristics at the ejector outlet and turbine inlet underline the potential of the ejector to couple the RDC with an axial turbine. Total pressure fluctuations are dampened by 65%, whereas the Mach number and the total temperature distortion are reduced to acceptable levels. [ABSTRACT FROM AUTHOR]