Search Results (196)

The cytosine methylation status of symmetric and asymmetric sites of promoters of the genes encoding the membrane-bound subunits C and D of succinate dehydrogenase (SDH) was assessed during the germination of maize (Zea mays L.) seeds, when the stored lipids were utilized and the glyoxylate cycle produced succinate. The results of bisulfite sequencing of the promoters of Sdh genes in maize scutella allowed us to determine the cytosine methylation status in the CG, CNG, and CNN sites. The observed site-specific changes in the cytosine methylation status of the Sdh3-1 and Sdh3-2 genes encoding the SDH subunit C indicate an important role in controlling their transcriptional activity. In contrast, no marked changes were observed in the methylation of promoters of the Sdh4 gene, encoding SDH subunit D. The analysis of changes in the activity of the CG, CNG, and CNN DNA methyltransferases revealed the redistribution of activity between CG, CNG, and CNN DNA methyltransferases toward an increase in the proportion of CG DNA methyltransferases. The locus-specific methylation dynamics of SDH membrane subunit promoters during maize germination have been demonstrated. It is concluded that the changes in the cytosine methylation status may play a role in the regulation of the expression of the Sdh genes in the course of the conversion of succinate formed in the glyoxylate cycle. Full article

Universities play a critical role in shaping sustainable mobility strategies, especially in urban contexts where the institutional transport system can influence environmental and social outcomes. This study integrates Environmental and Social Life Cycle Assessment (E-LCA and S-LCA) to evaluate the current university transport system from internal combustion engines, diesel, and compressed natural gas (CNG), focusing on the operation and maintenance phases. Also, it compares seven scenarios, including electric, renewable sources, and biodiesel technologies. Environmental impacts were assessed using the ReCiPe 2016 midpoint method, which considers the following impact categories: Global Warming Potential (GWP); Ozone Formation, Human Health (OfHh); Ozone Formation, Terrestrial Ecosystem (OfTe); Terrestrial Acidification (TA); and Fine Particulate Matter Formation (FPmf). The sensitivity analysis explores scenarios to assess the effects of technological transitions and alternative energy sources on the environmental performance. Social impacts are assessed through a Social Performance Index (SPI) and Aggregated Social Performance Index (ASPI), which aggregates indicators such as safety, travel cost, punctuality, accessibility, and inclusive design. Accessibility emerged as the lowest indicator (ranging from 0.61 to 0.67), highlighting opportunities for improvement. Our findings support decision-making processes for integrating sustainable transport strategies into a University Mobility Plan, emphasizing the importance of combining technical performance with social inclusivity. Full article

Soil respiration (Rt), consisting of heterotrophic (Rh) and autotrophic respiration (Ra), plays a vital role in terrestrial carbon cycling and is sensitive to soil temperature and moisture. In dryland agriculture, plastic film mulching (PM) is widely used to regulate soil hydrothermal conditions, but its effects on Rt components and their temperature sensitivity (Q₁₀) across regions remain unclear. A two-year field study was conducted at two rain-fed maize sites: Anding (warmer, semi-arid) and Yuzhong (colder, drier). PM significantly increased Rt, Rh, and Ra, especially Ra, due to enhanced root biomass and improved microclimate. Yield increased by 33.6–165%. Peak respiration occurred earlier in Anding, aligned with maize growth and soil temperature. PM reduced Q₁₀ of Rt and Ra in Anding, but only Ra in Yuzhong. Rh Q₁₀ remained stable, indicating microbial respiration was less sensitive to temperature changes. Structural equation modeling revealed that Rt and Ra were mainly driven by soil temperature and root biomass, while Rh was more influenced by microbial biomass carbon (MBC) and dissolved organic carbon (DOC). Despite increased CO₂ emissions, PM improved carbon emission efficiency (CEE), particularly in Yuzhong (+67%). The application of PM is recommended to enhance yield while optimizing carbon efficiency in dryland farming systems. Full article

The transportation sector in South Asia largely depends on internal combustion engine (ICE) vehicles, which are responsible for a large share of greenhouse gas (GHG) emissions, air pollution, and the increase in fuel prices. Although hybrid electric vehicles (HEVs), plug-in hybrid electric vehicles (PHEVs), and fully electric vehicles (EVs) constitute promising alternatives, the rate of their implementation is low due to factors such as the high initial investment, the absence of the required infrastructure, and the reliance on fossil fuel-based electricity. This study is the first of its kind to examine Bangladesh’s drivetrain options in a comprehensive way, with in-depth real-world emission testing and economic analysis as the main tools of investigation into the environmental and economic feasibility of different technologies used in the vehicles available in Bangladesh, including lifecycle costs and infrastructure constraints. The study findings have shown that hybrid and plug-in hybrid vehicles are the best options, since they have moderate emissions and cost efficiency, respectively. Fully electric vehicles, however, face two main challenges: the overall lack of charging infrastructure and the overall high purchase prices. Among the evaluated technologies, PHEVs exhibited the lowest environmental and economic burden. The Toyota Prius PHEV emitted 98% less NOx compared to the diesel-powered Pajero Sport and maintained the lowest per-kilometer cost at BDT 6.39. In contrast, diesel SUVs emitted 178 ppm NOx and cost 22.62 BDT/km, reinforcing the transitional advantage of plug-in hybrid technology in Bangladesh’s context. Full article

The global climate crisis necessitates the urgent implementation of sustainable practices and carbon emission reduction strategies across all sectors. Transport, as a major contributor to greenhouse gas emissions, requires transitional technologies to bridge the gap between fossil fuel dependency and renewable energy systems. Natural gas, recognised as the cleanest fossil-derived fuel with approximately half the CO₂ emissions of coal and 75% of oil, presents a potential transitional solution through Natural Gas Vehicles (NGVs). This manuscript presents several distinctive contributions that advance the understanding of Natural Gas Vehicles within the contemporary energy transition landscape while synthesising updated emission performance data. Specifically, the feasibility and sustainability of NGVs are investigated within the energy transition framework by systematically incorporating recent technological developments and environmental, economic, and infrastructure considerations in comparison to conventional vehicles (diesel and petrol) and unconventional alternatives (electric and hydrogen-fuelled). The analysis reveals that NGVs can reduce CO₂ emissions by approximately 25% compared to petrol vehicles on a well-to-wheel basis, with significant reductions in NO_x and particulate matter. However, these environmental benefits depend heavily on the source and type of natural gas used (CNG or LNG), while economic viability hinges largely on governmental policies and infrastructure development. The findings suggest that NGVs can serve as an effective transitional technology in the transport sector’s sustainability pathway, particularly in regions with established natural gas infrastructure, but require supportive policy frameworks to overcome implementation barriers. Full article

Compressed natural gas (CNG) refueling stations operate under highly dynamic thermodynamic conditions, requiring accurate modeling and optimization to ensure efficient performance. In this study, a dynamic simulation model of a CNG station was developed using MATLAB-SIMULINK, including detailed subsystems for multi-stage compression, cascade storage, and vehicle tank filling. Real gas effects were incorporated to improve prediction accuracy of the pressure, temperature, and mass flow rate variations during fast filling. The model was validated against experimental data, showing good agreement in both pressure rise and flow rate evolution. A two-stage multi-objective optimization approach was applied using Taguchi experimental design and gray relational analysis (GRA). In the first stage, storage pressures were optimized to maximize the number of vehicles filled and gas mass delivered, while minimizing compressor-specific work. The second stage focused on optimizing the volume distribution among the low, medium, and high-pressure tanks. The combined optimization led to a 12.33% reduction in compressor-specific energy consumption with minimal change in refueling throughput. These results highlight the critical influence of pressure levels and volume ratios in cascade storage systems on station performance. The presented methodology provides a systematic framework for the analysis and optimization of transient operating conditions in CNG infrastructure. Full article

This study investigates the performance and combustion behavior of a spark ignition engine retrofitted to operate on compressed natural gas (CNG), with a focus on a newly developed stratified charge pre-chamber design. The engine was modified to include an auxiliary intake valve that enables partial enrichment of the pre-chamber mixture without the need for a dedicated fuel injector. This hybrid approach combines the mechanical simplicity of passive systems with the enhanced combustion control of active pre-chambers. Both experimental tests and computational fluid dynamics (CFD) analyses were carried out under partial load conditions (8 Nm) and engine speeds ranging from 900 to 1700 rpm. The results demonstrate improvements in indicated mean effective pressure (IMEP), combustion stability, and flame propagation speed—particularly at lower engine speeds where stratified combustion effects are more pronounced. However, increasing engine speed resulted in reduced volumetric efficiency and elevated exhaust temperatures, indicating potential for further optimization via turbocharging or advanced scavenging techniques. Overall, the findings validate the effectiveness of the proposed design in enhancing thermal efficiency and ignition stability in CNG-fueled engines, especially under urban driving conditions. Full article

Compressed natural gas (CNG) in dual-fuel diesel engines offers environmental benefits but significantly increases unburned methane (CH₄) emissions, especially at low engine loads. This study investigates the effectiveness of different catalytic converters in methane oxidation under transient test conditions (WHTC). Three types of catalysts (Pt-, Rh-, and Pd-based) were evaluated using a combined approach of empirical engine bench tests and mathematical modelling. The results showed that, under actual exhaust gas temperature conditions, the average methane conversion efficiencies were 3.7% for Pt, 17.7% for Rh, and 31.3% for Pd catalysts. Increasing the exhaust gas temperature by 50% improved the conversion efficiencies to 7.3%, 51.8%, and 69.2%, respectively. Despite this enhancement, none of the catalysts reached the 90% efficiency threshold required to increase the CNG content of the fuel beyond 6% without exceeding emission limits. The results highlight the need for high-activity Pd-based catalysts and optimised thermal management strategies to enable the broader adoption of dual-fuel engines, while complying with Euro VI standards. Full article

Natural and liquefied petroleum gases are widely used in industrial heat treatment. However, the rising cost of gas, combined with increased demand, has significantly impacted production costs and the environment. The annealing process typically relies on natural or liquefied petroleum gases as the primary heat source. In this study, we aimed to investigate the use of biomass fuel as a replacement for fossil fuels and to evaluate the mechanical properties and microstructure of wire rod steel after annealing using indirect heat from a gasifier. We experimented to examine the effects of annealing temperatures of 650 °C, 700 °C (below the critical temperature Ac1), and 750 °C (above Ac1 but below the upper temperature Ac3). The batch furnace, made of stainless steel, was modified from a traditional wire annealing furnace that originally used CNG and LPG gas burners. It was adapted into a wire annealing furnace connected to a cross-draft gasifier. The furnace’s interior was designed with spiral cooling fins to minimize energy consumption and shorten annealing time. Additionally, it was modified to use biomass as a substitute fuel, reducing environmental pollution. The furnace was coated with thermal insulation, and the biomass gasifier stove was a cross-draft device with primary air feeding at 20 m³/h and secondary air supplied at a constant flow rate of 32 m³/h, 36 m³/h, or 40 m³/h. As a fuel source, we used eucalyptus. The mechanical properties of wire rod steel were measured in terms of tensile strength and torsion, following the TIS 138-2562 standard. This standard specifies that the tensile strength must be at least 260 MPa. Regarding torsion, the TIS 138-2562 requirements state that the wire must withstand at least 75 rounds of twisting without breaking. Our results showed that after annealing at 650 °C, 700 °C, or 750 °C, with a soaking time of 30 min and subsequent cooling in the furnace at natural temperature for 24 h, the tensile strength values were 494.82, 430.87, and 381.33 MPa, respectively. The torsion values were 126.92, 125.8, and 125.76 rounds, respectively. Additionally, ferrite grain size increased with annealing temperature, reaching a maximum of 750 °C. The total annealing duration for each batch was 2 h and 40 min at 650 °C, 2 h and 10 min at 700 °C, and 2 h at 750 °C. Full article

This study develops and validates a three-dimensional CFD model for a 12 L large-bore active-type pre-chamber spark-ignition (PCSI) engine fueled by natural gas. The model incorporates an advanced Extended Coherent Flamelet Model (ECFM-3Z) with a tuned stretch factor to capture complex turbulence–flame interactions, flame propagation, and pollutant formation under ultra-lean conditions. By systematically varying pre-chamber geometries—specifically the orifice diameter, cone angle, diverging tapered nozzle, and volume—the simulations assess their effects on combustion dynamics, heat release rates, turbulent jet penetration, and emissions (NOx and CO). Model predictions of in-cylinder and pre-chamber pressure profiles, combustion phasing, and emission trends are validated against experimental data. The results demonstrate that optimizing pre-chamber and orifice configurations enhances turbulent mixing, accelerates flame development, and reduces local high-temperature zones, thereby suppressing NOx and CO formation. Although some discrepancies in NOx predictions persist due to limitations in current turbulence–chemistry models, the findings offer valuable insights for the design of high-efficiency, low-emission PCSI engines. Full article

Urban transportation is a key contributor to air pollution in cities. While urban buses impact air quality, they also promote sustainable mobility. In the Paris region, buses account for approximately 4% of traffic emissions. This study addresses the gap in real-world emissions data for Euro VI diesel, diesel-hybrid, and compressed natural gas (CNG) urban buses by developing speed-dependent emission factors for CO, NO_X, SPN₂₃, and energy consumption. An optimized methodology was applied to portable emission measurement system data collected from 28 urban buses across various routes in the Paris metropolitan area, capturing emissions across different speeds and traffic conditions. Results showed that diesel buses emit around 2 g/km of NOx at low speeds, compared to 1.4 g/km for diesel hybrids and 0.6 g/km for CNG. CO emissions reached approximately 1 g/km for CNG and 0.5 g/km for diesel, while SPN₂₃ emissions for all powertrains were in the order of 10¹² particles/km. The resulting speed-dependent emission factors were incorporated into COPERT version 5.8, the European Union’s standard emission inventory software, improving the inventory accuracy. The findings underscore the need for additional reductions in air pollutant emissions to meet Euro 7 standards and provide a robust framework for improving air quality management. Full article

African swine fever virus (ASFV) is the causative agent of African swine fever (ASF), a severe hemorrhagic disease with a mortality rate reaching 100%. Despite extensive research on ASFV mechanisms, no safe and effective vaccines or antiviral treatments have been developed. Live attenuated vaccines generated via gene deletion are considered to be highly promising. We developed a novel recombinant ASFV strain by deleting MGF360-10L and MGF505-7R, significantly reducing virulence in pigs. In the inoculation experiment, pigs were infected with 10⁴ 50% hemadsorption doses (HAD₅₀) of the mutant strain. All the animals survived the observation period without showing ASF-related clinical signs. Importantly, no significant viral infections were detected in the cohabitating pigs. In the virus challenge experiment, all pigs succumbed after being challenged with the parent strain. RNA-seq analysis showed that the recombinant virus induced slightly higher expression of natural immune factors than the parent ASFV; however, this level was insufficient to provide immune protection. In conclusion, our study demonstrates that deleting MGF360-10L and MGF505-7R from ASFV CN/GS/2018 significantly reduces virulence but fails to provide protection against the parent strain. Full article

The alumina, in the form of α-Al₂O₃ tabular balls, considered in this study is a high-purity form of aluminum oxide that has been fired at high temperatures (well above 1900 °C), virtually removing porosity. However, the purity and inertness of the surface of the Al₂O₃ tabular balls minimize the catalytic activity, which is why lithium doping was tried. Thus, the target of this study was the effect of doping with lithium ions in some tabular balls of Al₂O₃ (the crystalline structure is corundum) on the improvement of the catalytic properties of alumina. This study examined the impact of a lithium catalyst on the combustion of various fuels within a porous inert medium (PIM) burner. This study specifically compared low calorific gaseous fuel (e.g., biogas) combustion in a PIM burner with and without the lithium catalyst. The experimental setup comprised a gas preparation unit for mixing CNG and CO₂ to simulate biogas and a PIM burner. The PIM burner comprised Al₂O₃ spheres (13 mm diameter, 45% porosity) in a random packing configuration. Three fuels, varying in composition and lower heating value (LHV ranging from 20.771 to 27.695 MJ/m³), were combusted at air ratios ranging from 1.67 to 1.79. The results indicated that the catalyst increased peak combustion temperatures by 23.2 °C to 51.4 °C, depending on the fuel type and air ratio. Significantly higher carbon monoxide (CO) concentrations were observed without the catalyst, particularly with fuel type F1, while nitrous oxide (NOx) levels remained consistently low. Upstream flame propagation was observed in the presence of the catalyst. These findings demonstrate the potential of lithium catalysts to enhance combustion stability and reduce emissions in porous media combustion burners. Following these studies, it can be stated that Li(I) has the role of promoter of the catalytic process. Full article

Particle number concentration (PN) in vehicle exhaust and ambient air describes the number of ultrafine particles (UFPs) below 500 nm, which are recognized as a toxic and carcinogenic component of pollution and are regulated in several countries. Metal nuclei, ash, and organic matter contribute significantly to the ultrafine particle size fraction and, thus, to the particle number concentration. Exhaust gas filtration is increasingly being used worldwide to significantly reduce this pollution, both on diesel particulate filter (DPF) and gasoline particulate filter (GPF) engines. In recent years, the EU has also funded research projects dealing with the possibilities of retrofitting gasoline vehicles with GPFs. This paper presents the results and compares the PN emissions of different vehicles. An original equipment manufacturer (OEM) diesel car with a DPF is considered as a benchmark. The PN emissions of this car are compared with a CNG car without filtration and with gasoline cars equipped with GPFs. It can be concluded that the currently used GPFs still have some potential to improve their filtration efficiency and that a modern CNG car would still have remarkable possibilities to reduce PN emissions with an improved quality GPF. Full article

This paper examines the feasibility of converting a Heavy-Duty (HD) Spark Ignition (SI) Compressed Natural Gas (CNG) engine to biogas fuel. A One-Dimensional (1D) simulation tool was used to model a commercially available HD SI CNG engine. The model was validated by comparing experimental and computed in-cylinder pressure, brake power, fuel, and air mass flow rates. The engine was then modified to use biogas with an injection system based on existing designs from the literature. A Spark Advance (SA) sweep was performed to assess the engine’s performance at full load. The chosen equivalence ratio was 0.85, and the engine speed was 1500 rpm. The Maximum Brake Power (MBP) and Maximum Brake Efficiency (MBE) operating points were identified. Partial load analysis was conducted starting from the MBP conditions. Results in terms of brake power, brake efficiency, and NO_x emissions are presented. Conversion to biofuel results in a reduction in power and efficiency of 33% and 4%, respectively, at 1500 rpm and full load conditions. Brake Specific NO_x emissions remained comparable. This numerical study demonstrates the feasibility of biogas conversion for HD SI engines, offering a renewable fuel alternative to reduce greenhouse gas emissions, though with trade-offs in power and efficiency. Full article