Low Carbon Content Research Articles

Physical, mechanical and microstructural properties of ultra-lightweight high-strength geopolymeric composites

A light weight, high strength and low carbon content are the main characteristics of modern concrete that meet requirements for functionality and environmental considerations of engineering structures. In this study, ultra-lightweight high-strength geopolymeric composites (ULHSGCs) were developed using fly ash cenospheres and hollow glass microspheres as aggregates and ground granulated blast furnace slag and silica fume as binders. This investigation focused on the physical, mechanical and microstructural properties of the ULHSGCs. A series of tests were conducted to examine the influence of the key factors on the flowability, setting times, mechanical properties and microstructure. The various tested parameters included the (1) silica fume content (10 %, 12.5 % and 15 %), (2) Na2O content (5 %, 6 % and 7 %); (3) alkali modulus (1.25, 1.5 and 1.75), (4) fibre type (polypropylene fibre and polyethylene fibre), and (5) fibre length (12 mm and 18 mm). The results showed that the density of the proposed ULHSGCs was less than 1500 kg/m3, while the compressive strength was above 70 MPa and the tensile strain capacity was up to 5.3 %. A higher Na2O content and a lower alkali modulus could provide better mechanical properties and fluidity but with a shorter setting time. The addition of 0.5 vol% fibre could effectively improve the mechanical properties without affecting the fresh properties. Due to good bonding to the matrix, the polyethylene fibres allowed the ULHSGCs to achieve pseudo-strain hardening under tensile or flexural loading.

Theoretical aspects of the use of hydrogen in the diesel engine

The promotion of fuels with low carbon content is the solution to reduce pollutant emissions in all areas of transport in a relatively short time. In this context, hydrogen is privileged, being a viable alternative fuel for internal combustion engines in all fields of transport, having the advantage of preserving the basic structure of the engine. The main obstacles to the large-scale expansion of the use of hydrogen as a fuel in internal combustion engines in transport are determined by the cost of production, storage on board the vehicle and the distribution network, large investments being required. The concept of using hydrogen as an alternative fuel to the diesel engine is relatively recent, the concerns of specialists being more intense in the last two decades. The improvement of the energy and pollution performance of the diesel engine when operating in a dual system, with diesel and hydrogen, is determined by the improvement of the combustion process due to the good combustion properties of hydrogen. The paper presents theoretical modeling results regarding the influence of hydrogen on the combustion pressure, the pressure rise rate, the heat release rate, the indicated efficiency and the nitrogen oxides emission level.

The short-term response of soil microbial communities to digestate application depends on the characteristics of the digestate and soil type

Anaerobic digestion of organic waste is a key process to produce renewable energy and meet the growing demand for sustainable energy. The residues of anaerobic digestion – called digestates – can be used as soil amendments to improve crop yields. However, the effect of digestates on the soil biota, especially on microorganisms, needs to be better documented before a large scale use of digestates in agriculture. In addition, how the quality and composition of the digestate may affect soil microbial communities has not been properly addressed yet. We designed a microcosm experiment under controlled experimental conditions to compare effects (42 days) of four digestates produced from varying intakes (cattle manure and/or energy crop and/or food residues and/or slurry) on soil microbial communities; a control microcosm made of undigested cattle manure was also used. Each digestate was applied on three contrasting soils representing contrasted pedo-climatic conditions (especially soil type and climate). These three soils presented different prokaryotic and fungal communities structures. The effect of digestate inputs on the soil microbial biomass and diversity was assessed using molecular DNA-based tools (quantification of extracted soil DNA and high-throughput sequencing, respectively) in comparison to the untreated cattle manure control condition. Our results show that 42 days after digestate application, significant differences of soil microbial communities were observed according to the digestate characteristics; these differences were soil-dependent. Thus, in the silty clay loam soil, no effect of digestates was observed on soil microbial biomass or diversity (P > 0.05), as compared to the undigested cattle manure. In the two other soil types (loam and sandy loam), soil microbial biomass decreased (around −40 %, P < 0.001) when digestates having a low total organic carbon content (from 0.61 to 3.3 g.100 g−1) were applied. None of the digestates affected the soil prokaryotic diversity whatever the soil type (P > 0.05). Digestate application resulted in higher fungal diversity (around +35 %; P < 0.001) in soils with low C/N ratio (9.14 in average). The microbial community structure of coarse-textured soil appeared more impacted by organic inputs than fine-textured soils. To conclude, our results show that different soil types, harboring distinct microbial community structures, responded differently to different digestates application. This response was also digestate-dependent.

Characterization of Soil Properties and Their Relationship with Various Sulphur Fractions in Groundnut Farming Regions of Bikaner District, India

An exploratory survey was conducted in Bikaner district during the 2015-16 kharif season to study the sulphur fractions and other soil properties in groundnut growing areas. 40 farmers from four tehsils (Lunkaransar, Shri Dungargarh, Nokha, and Kolayat) were selected for the study. Soil samples were collected and analyzed for pH, EC, CaCO3, organic carbon, soil texture, available nutrients (N, P2O5, K2O, S), and sulphur fractions. The results showed that the soils were sandy, loamy sand, and sandy loam in texture and alkaline in -pH. The majority of soils were calcareous with low organic carbon content. The available nitrogen was found to be low while available P2O5 and K2O were medium. The distribution of different forms of sulphur in soil was found to be strongly dependent on soil characteristics such as clay content, silt and organic carbon content. It is noted that for more productive growth of groundnut better fertilizer practices along with organic manure should be practiced so as to improve OC status as well as compensate for lower water holding capacity of sandy soils.

Study on the Effect of ELID Grinding on corrosion wear properties of Co-Cr Alloy

Contemporary Co-Cr alloys used in artificial joints can cause health complications in long-term applications. A pin-on-disc friction and wear testing instrument was used to evaluate the corrosion and abrasion of two types of Co-Cr alloys for artificial joints under simulated body fluid conditions after surface electrolytic composite grinding. Co-materials with lower carbon content displayed superior corrosion resistance than those materials with higher carbon content. Moreover, surface processing with electrolytic composite grinding produced a stable surface modification layer, which improved the surface hardness and formed an oxide film that inhibited metal ionization. The formation of precipitates in the corrosive environment is likely to improve the friction and wear properties of the material. As such, a variety of hardness was observed for the artificial joint friction disc and pin, especially when the hardness of the disc was higher than that of the pin, which can improve the friction and wear behavior of joints.

Spatial distribution of physico-chemical parameters of chestnut soils in small watersheds under the influence of forest strips

The soils of agricultural land are degraded, which affects their productivity. Soil properties reflect the ability of soil to prevent the processes of degradation. The article presents materials on the study of chestnut soils of Volgograd region in the system of protective forest belts on arid agricultural lands. The purpose of the study, conducted in 2021, was to establish the spatial impact of protective forest strips on the physico-chemical parameters of the soil in the conditions of a low steepness of the slope of the eastern exposition. To achieve this goal, we investigated theoretical and methodological materials on the experimental plot and studied the selected samples by conducting laboratory analyses of the main indicators (granulometric composition, soil structure coefficient, soil density, organic carbon). As a result of the study of samples from points near the forest belt and within it the following was revealed: high content of organic matter (up to 1.47%) and high density (up to 1.53 g/cm3), sandy loam soil with a light granulometric composition and high content of agronomically valuable aggregates (0.25-10 mm), the structure factor above 1.6. Outside the forest belt and up the slope low carbon content (not more than 0.84 %) low density (not more than 1.32 g/cm3), soil has heavy granulometric composition, structure coefficient decreases to 0.86.

Cobalt-molybdenum bimetallic catalyst effect on biomass-derived graphitic carbon

The development of highly graphitized and porous carbon materials is important for the evaluation of wastes and their use in energy applications. In this study, we focused on the production of simple, safe, and sustainable porous graphitic carbon (GC) materials using an important waste source in the Black Sea region. Catalytic graphitization method was used for the conversion of hazelnut shell powder with low ash (0.11 %) and high carbon (50.85 %) content to GC. The effects of metallic Co and bimetallic Co-Mo catalysts at different ratios on the graphitization mechanism as well as the chemical, structural and surface properties of the produced GCs were investigated. It was determined that Co:Mo= 1:4 is the most suitable ratio due to the emergent synergistic effect. In the HS-Co-Mo-1-4, the ID/IG ratio was found to be 0.876, while the Braun-Emmet-Teller surface area (SBET) was measured as 266.5 m2/g.

A resilient ice cover over the southernmost Mendeleev Ridge during the late Quaternary

The presence of a late Quaternary ice sheet/ice shelf over the East Siberian Sea has been proposed in several papers. Here, we further document its duration/resilience based on the sedimentary, bulk mineralogical, and geochemical (organic matter content and its stable isotopic composition, U‐Th series) properties of a core raised from the southernmost Mendeleev Ridge. The chronostratigraphy of the studied core was mainly built from the 230Th excess (230Thxs) distribution and decay downcore. At the core‐top, peaking 230Thxs values during the early MIS 3 and mid‐MIS 1 encompassing an MIS 2 hiatus were observed. As documented in several papers, these peaks suggest seasonally open ice conditions over proximal continental shelves. Below, the interval spanning MIS 4 and possibly MIS 5d records major ice‐rafting events illustrated by overall high coarse‐fraction contents. Underlying MIS 5e, down to MIS 11, the sediment depicts relatively low sand (1.7±2.5 dw%), high clay (33.5±4.7 dw%), and very low organic carbon (0.10±0.06 dw%) contents, and low δ13Corg values (−24.3±0.9‰). This section is interpreted as recording fine sediment transport by deep currents and/or meltwater plumes below a resilient ice cover, only interrupted by a few short‐duration events. These events include (i) detrital carbonate pulses assigned to deglacial events along the NW Laurentide Ice Sheet margin (Termination (T) III), and (ii) intervals with some planktonic foraminifer occurrences, likely relating to their advection from open areas of the Arctic Ocean (MIS 5e, 9 and 11). All Terminations, but TII and the early MIS 3, show peaking Mn/Al values linked to the submergence of Arctic shelves under a rising sea level. We conclude that the resilient ice cover, likely an ice shelf, has been present over the southern Mendeleev Ridge during most of the interval after the Mid‐Pleistocene Transition and was favoured by the low summer insolation of the MIS 14 to 10 interval.

Dodecylamine enhanced coal gasification fine slag flotation and its molecular dynamics simulation

Coal gasification fine slag (CGFS) is produced by the raw gas flow through the top of the gasifier, and is formed after preliminary washing and purification, precipitation, and dehydration. The CGFS cannot be directly used as building materials or in other industries because of its higher ignition loss than the standard of building mixed raw materials. Neither can it be used for direct combustion because of low carbon content, high moisture content and low calorific value. Currently, its treatment is mainly landfill-based disposal which causes environmental pollution and carbon resources waste. The utilization of CGFS is becoming increasingly urgent and its premise is the separation of ash material and residual carbon. Froth flotation is a common method used for separating fine materials. In this study, kerosene (D1) and a dodecylamine-kerosene mixture (D2) were used as collectors and the flotation performance of CGFS sampled from Ningxia Coal Industry Company was investigated. The results indicate that D2 is better than D1 in that it gives higher yield of concentrate, ash of tailings, and combustible recovery. Pore structure analysis (BET) and scanning electron microscopy energy dispersive spectroscopy (SEM-EDS) were used to characterize the flotation products, which provided a basis for the separate utilization of carbon ash from CGFS. In this paper, a certain percentage of functional groups were grafted onto graphene based on the results of XPS analysis to replace the residual carbon model, and the D2 collector is proved to be more efficient than D1 by two models. Molecular dynamics (MD) simulations was used to simulate the adsorption morphology of D1 and D2 on the surface of residual carbon and the adsorption morphology of D2 on the surface of residual carbon with four functional groups. The results show that D2 has stronger adsorption energy with residual carbon than D1, and the electrostatic forces play a certain role. The adsorption energy of D2 with four functional groups decreases from carboxyl, carbonyl, hydroxyl, to ether bonds. Some dodecylamine molecules help kerosene to form smaller oil droplets that act on the carbon residue surface through van der Waals (vdW) force and electrostatic force, while other dodecylamine molecules form hydrogen bonds with oxygen-containing functional groups on the carbon surface to cover some hydrophilic points. This significantly increases the hydrophobicity of the residual carbon and enhances its flotation effect.

Preparation, properties, and interfacial bonding mechanism of MgO–Mg2SiO4–SiC–C refractories

Because the thermal shock resistance of MgO–C refractories decreases with carbon content, the development of new high-performance magnesia based refractories is necessitated. In this study, MgO–Mg2SiO4–SiC–C refractories with low carbon content and high thermal shock resistance were prepared using MgO–Mg2SiO4 as the aggregates and MgO–SiC–C as the matrix. Based on the analysis of the Hasselman thermal shock stability factor, the thermal shock resistance of the MgO–Mg2SiO4–SiC–C refractories was enhanced by reducing the thermal expansion coefficient, increasing the elastic modulus, and improving the fracture toughness. Molecular dynamics simulations of the dynamic process of interface bonding varying with temperature showed that SiC and Mg2SiO4 in MgO–Mg2SiO4–SiC–C refractories could serve as media for indirectly binding MgO and C, thus forming a network that effectively strengthened the refractories.

Response of Sulphur and Molybdenum on Growth and Yield Attributes of Field Pea (Pisum sativum L.)

During Rabi 2022, a field trial was conducted at the SHUATS Agriculture Crop Research Farm in Prayagraj. The soil in the experimental plot was sandy loamy, with a near-neutral soil response (pH 7.1), low organic carbon content (0.36%), available nitrogen (171.48 kg/ha), available phosphorus (15.2 kg/ha), and had an effective soil. K (232.5 kg/ha). The experiment was set up with a randomized block design in which he repeated nine treatments three times, based on a one-year experiment. The treatments are T1: Sulphur 20 kg/ha-1 + Mo 0.5 kg/ha-1, T2: Sulphur 20 kg/ha- 1 + Mo 1.0 kg/ha-1, T3: Sulphur 20 kg/ha-1 + Mo 1.5 kg/ha-1, T4: Sulphur 30 kg/ha-1 + Mo 0.5 kg/ha- 1, T5: Sulphur 30 kg/ha-1 + Mo 1.0 kg/ha-1, T6: Sulphur 30 kg/ha-1 + Mo 1.5 kg/ha-1, T7: Sulphur 40 kg/ha-1 + Mo 0.5 kg/ha-1, T8: Sulphur 40 kg/ha-1 + Mo 1.0 kg/ha-1, T9: Sulphur 40 kg/ha-1 + Mo 1.5 kg/ha-1, T10: Control are used. The application of Sulphur 40 kg/ha-1 + Mo 0.5 kg/ha-1, recorded significant Plant height (56.25 cm), Number of nodules/plant (9.00), Plant dry weight (22.13 g/plant), maximum pods/plant (19.00), Seeds/pod (8.21), Test weight (35.45 g), Seed yield (2.29 t/ha).

Efficient in-situ conversion of low-concentration carbon dioxide in exhaust gas using silver nanoparticles in N-heterocyclic carbene polymer

Efficient utilizing CO2 is crucial approaches in achieving carbon neutralization. One of the challenges lies in the in-situ conversion of low concentration CO2 found in waste gases. This study introduces a novel heterogeneous catalyst known as silver nanoparticles in porous N-heterocyclic carbene polymer (Ag@POP-NL-3). The catalyst is synthesized via a streamlined pre-coordination method. Ag@POP-NL-3 exhibits uniform distribution of silver nanoparticles, a porous structure and nitrogen activation groups. It demonstrates high efficiency and selectivity in absorbing and activating CO2 and enabling the conversion of low concentration CO2 (30 vol%) from lime kiln waste gas into cyclic carbonate under mild conditions. This catalytic system achieves both CO2 capture and resource utilization of CO2 simultaneously, effectively fixing low-concentration CO2 from waste gases into C2+ valuable chemicals. This approach elegantly addresses two goals in one solution.

Marine estuaries act as better sink for greenhouse gases during winter in undisturbed mangrove than degraded ones in Sundarban, India

The estuaries provide the key pathway for travelling carbon across the land-ocean interfaces and behave as both source and sink of greenhouse gases (GHGs) in water-atmosphere systems. The sink-source characteristics of estuaries for GHGs vary spatially. The primary driving factors are adjacent ecologies (agriculture, aquaculture, etc.) and proximities to the sea. To study the sink-source characteristics of estuaries for GHGs (methane (CH4), nitrous oxide (N2O) and carbon dioxide (CO2)), the water samples were collected from 53 different locations in the estuaries for estimation of dissolved GHGs concentration and air-water GHGs exchanges. The locations represent five zones (Zone I, II, III, IV and V) based on the type and degradation status of mangroves (degraded and undisturbed), anthropogenic activities, and distance from the sea. Zone I, III, V represents to the degraded mangroves far from sea, whereas, Zone II, IV surrounded by undisturbed mangroves and nearer to sea. The average dissolved CH4 concentrations were higher in the estuaries which were adjacent to degraded mangroves (154.4 nmol L−1) than undisturbed mangroves (81.7 nmol L−1). Further, the average dissolved N2O concentrations were 48% higher in the estuaries nearer to degraded mangroves than that of undisturbed ones. Among the degraded mangrove sites, the dissolved CO2 concentrations were higher at Zone I (30.1 μmol L−1) followed by Zone III and IV, whereas in undisturbed sites, it was higher in Zone IV (22.3 μmol L−1) than Zone II (17.6 μmol L−1). Among the 53 locations, 36, 51 and 33 locations acted as a sink (negative value of exchanges) for CH4, N2O and CO2, respectively. The higher sink potential for CH4 was recorded to those estuaries adjacent to undisturbed mangroves (−791.69 μmol m−2 d−1) than the degraded ones (−23.18 μmol m−2 d−1). Similarly, the average air-water N2O and CO2 exchanges were more negative in the estuaries which were nearer to undisturbed mangroves indicating higher sink potential. The pH, and salinity of the estuary water were negatively correlated with air-water CH4 and N2O exchanges, whereas those were positively correlated with CO2 exchanges. Significantly lower dissolved GHGs and air-water GHGs exchange was observed in the estuaries adjacent to the undisturbed mangrove as compared to the degraded mangrove. The reason behind higher sink behaviours of estuaries nearer to undisturbed mangroves are higher intrusion of seawater, less nutrient availability, higher salinity, low carbon contents and alkaline pH compared to estuaries adjacent to degraded mangroves and far from sea.

Seasonal patterns in microbial carbon and iron transporter expression in the Southern Ocean

BackgroundHeterotrophic microbes in the Southern Ocean are challenged by the double constraint of low concentrations of organic carbon (C) and iron (Fe). These essential elements are tightly coupled in cellular processes; however, the prokaryotic requirements of C and Fe under varying environmental settings remain poorly studied. Here, we used a combination of metatranscriptomics and metaproteomics to identify prokaryotic membrane transporters for organic substrates and Fe in naturally iron-fertilized and high-nutrient, low-chlorophyll waters of the Southern Ocean during spring and late summer.ResultsPronounced differences in membrane transporter profiles between seasons were observed at both sites, both at the transcript and protein level. When specific compound classes were considered, the two approaches revealed different patterns. At the transcript level, seasonal patterns were only observed for subsets of genes belonging to each transporter category. At the protein level, membrane transporters of organic compounds were relatively more abundant in spring as compared to summer, while the opposite pattern was observed for Fe transporters. These observations suggest an enhanced requirement for organic C in early spring and for Fe in late summer. Mapping transcripts and proteins to 50 metagenomic-assembled genomes revealed distinct taxon-specific seasonal differences pointing to potentially opportunistic clades, such as Pseudomonadales and Nitrincolaceae, and groups with a more restricted repertoire of expressed transporters, such as Alphaproteobacteria and Flavobacteriaceae.ConclusionThe combined investigations of C and Fe membrane transporters suggest seasonal changes in the microbial requirements of these elements under different productivity regimes. The taxon-specific acquisition strategies of different forms of C and Fe illustrate how diverse microbes could shape transcript and protein expression profiles at the community level at different seasons. Our results on the C- and Fe-related metabolic capabilities of microbial taxa provide new insights into their potential role in the cycling of C and Fe under varying nutrient regimes in the Southern Ocean.AY3puCcyJmqkMsR1qwvg2VVideo

Small carbon stocks in sediments of Baltic Sea eelgrass meadows

Seagrass meadows act as an effective carbon sink and store carbon in the sediments for substantial periods of time. The drivers of carbon sequestration are complex, and global and regional estimates of carbon stocks have large uncertainties. Here, we report new carbon stock estimates from 14 sites along the Swedish coast and compile existing literature to estimate the magnitude of carbon stocks of Zostera marina (eelgrass) meadows in the Baltic Sea. Eelgrass meadows in the Baltic Sea have considerably lower carbon content and lower stocks (0.25 ± 0.21% DW, 635 ± 321 g C m-2) than in the Kattegat-Skagerrak region (3.25 ± 2.78% DW, 3457 ± 3382 g C m-2) and the average for temperate regions in general (1.4 ± 0.4% DW, 2721 ± 989 g C m-2). Unfavorable growing conditions for eelgrass in the Baltic Sea often lead to meadows occurring in areas of high hydrodynamics, preventing significant carbon accumulation. Stable isotopes revealed that the dominating source of organic carbon in the meadows was planktonic, further highlighting that Baltic Sea eelgrass meadows are not major carbon reservoirs in comparison to unvegetated sediments and other seagrass areas. The results also highlight that environmental conditions drive intraspecific variation of carbon sequestration on large spatial scales. Overall, the carbon stocks and sequestration potential in eelgrass meadows of the Baltic Sea are small compared to other temperate regions.

Revitalizing sub-optimal drylands: Exploring the role of biofertilizers

Abstract Indonesia has a dry land area of 79.69%, with low soil productivity (physical, chemical, and biological), as well as uneven and unpredictable rainfall. The dryland potential is optimally utilized using biofertilizers that can produce microbes to increase soil fertility. This research aims to determine the effects of biofertilizers on dryland improvement and crop production. The study was conducted from February to May 2021 in Central Java, Indonesia. Using a randomized block design in peanut cultivation. Six biofertilizers (Controlled, Agrimeth, BioNutrient, Gliocompost, Agrimeth + BioNutrient, Agrimeth + BioNutrient + Gliocompost) were applied with four replications. The performance of each biofertilizer was assessed based on chemical soil parameters, soil microbe population, plant growth, and yields. The soil in the study area belonged to the Inceptisols group and exhibited moderately acidic pH, low organic carbon content, and low nitrogen levels. However, it had high potential and available phosphorus, as well as moderate potential and high available potassium. BioNutrient and Gliocompost increased available phosphate by 12 and 19%, respectively, due to the presence of Pseudomonas fluorescens and Aspergillus sp. Agrimeth influenced the population of Azospirillum (45–63%) and enhanced phosphate-solubilizing bacteria. Agrimeth + BioNutrient + Gliocompost promoted the growth of the Azospirillum and Trichoderma populations (17–18%), resulting in a 45.04% increase in profits. Biofertilizer inoculation positively affected peanut development, root nodule formation, and yield. This novelty showed the potential of biofertilizers in improving dryland conditions, increasing crop productivity, and contributing to sustainable agriculture in the long term.

ANAEROBIC CO-DIGESTION OF MICROALGAE AND RESIDUAL GLYCEROL RECOVERED FROM BIODIESEL: EVALUATION OF PRETREATMENT AND COD/N RATIO

Anaerobic digestion can be a viable alternative for the destination of effluents from stabilization ponds rich in naturally produced microalgae, without the need for concentration processes, however, there are challenges related to the rigid cell wall of microalgae and the low carbon content in its composition, to be overcome. To improve these parameters, this study comparatively evaluated hydrolytic pretreatments in microalgae from effluents from stabilization ponds, aiming to hydrolyze the cell wall of these microorganisms, for co-digestion with residual glycerol from biodiesel. In this case, glycerol is a by-product with limited applicability, acting in this scenario as a carbon supplier, improving the C/N ratio, microalgae biodegradation and biomethane production. Effluents with microalgae submitted to thermal and ultrasonic hydrolysis (for 30 and 90 minutes) were tested to assess their potential in the production of methane-rich biogas, monitored by gauge measurements and gas chromatography, respectively, in co-digestion with residual glycerol from biodiesel. The heat treatment for 30 minutes showed more satisfactory results and was replicated in a benchtop anaerobic reactor (R2), in parallel with a reactor operating untreated microalgae (R1), in a continuous feed system. The effects of pretreatment and COD/N ratio were evaluated on organic matter removal and biomethane production. R2 showed the most satisfactory effect on COD removal, resulting in up to 90% COD removed, with a theoretical biogas production of 0.52 L g-1 COD removed. As for the methane content contained in biogas, R1 reached percentages of up to 84% against 73% in R2.

Experimental investigations on SI engine with piston coatings and gasoline blends

Internal combustion engine fuel use is rising, gas prices are fluctuating, we are using less fossil fuels and natural resources, and we need to develop alternative fuels with lower carbon contents. This study compares several gasoline mixtures in a single-cylinder, two-stroke SI engine. The current experimental work provides a thermal barrier for gasoline mixtures containing ethanol, butanol, and propanol by 100-µm piston crown coatings of magnesium partially stabilized zirconium (Mg-PSZ). 20% ethanol and 80% gasoline, 20% butane and 80% gasoline, and 20% propane and 80% gasoline made up the fuel mixture samples. The following engine variables must be assessed in this experiment for coated and uncoated pistons: brake-thermal efficiency (BTH), specific fuel consumption (SFC), and HC and CO emissions. According to the experiment findings, employing E20 resulted in a 4% gain in thermal efficiency, a 1.78% decrease in specific fuel consumption, and a 2.0% and 2.4% decrease in HC and CO exhaust emissions. The results show that heat barrier coatings and gasoline blends (E20) may improve engine performance while lowering exhaust emissions.

Numerical investigation on the effect of methane diffusion flame parameters toward the carbon nanotubes growth inside quasi-pyrolysis chamber

Flame synthesis exhibits significant potential for mass-producing carbon nanotubes (CNTs). In this study, we have developed a computational fluid dynamics (CFD) model at the flame scale and employed a CNT growth rate model (GRM) to predict CNT growth within a quasi-pyrolysis chamber. The investigation explores the influence of fuel concentration in a methane diffusion flame on the resulting length of synthesized CNTs within this chamber. As methane concentration decreases via nitrogen dilution, shorter methane diffusion flame lengths are observed atop the burner, accompanied by a reduction in flame temperature. Notably, CNTs are not produced when the fuel concentration falls below 92 vol% due to the low temperature and minimal carbon concentration in the synthesis chamber. Interestingly, the maximum synthesized CNT length increases by 1.248 μm as the fuel concentration shifts from 100to 97 vol%. This increase is attributed to the conducive thermochemical conditions within the synthesis chamber. However, this trend reverses and culminates in zero length when the fuel concentration reaches 92 vol%. The temperature range of 875–905 K is identified as favorable for CNT growth, resulting in CNTs with lengths ranging from 4.0 μm to 4.7 μm.

Effect of near-surface winds on the measurement of forest soil CO2 fluxes using closed air chambers

Forest soil CO2 flux measurements are important for studying global climate change. Current monitoring methods are based on closed gas chambers, which block the wind pumping effect of near-surface winds in the measurements, resulting in biased values. Therefore, in this study, the effects of near-surface winds on chamber-monitored fluxes were investigated. The CO2 flux was quantified using a designed flux reference system with different CO2 concentrations, and the monitoring performance of the closed chamber was studied. Wavelet coherence was used to analyze the response relationship between near-surface winds and soil gas, and was combined with a flux calculation model to explore the relevant factors influencing gas chamber measurement-produced bias. The data indicate that at near-surface wind speeds greater than 0.8 m·s−1, gas transport enhancement was significant and further increased the deviation of the gas chamber-monitored CO2 fluxes. The monitoring error of the flow chamber (NSF) increased from 7% to 30% in soils with low carbon content, but did not vary significantly (3–7%) in soils with high CO2 concentrations. The flux measurement bias of the non-flow chamber (NSNF) was positively correlated with the soil carbon content, with the measurement error expanding by 16–24% with increasing soil CO2 concentrations. The measurement errors of the exponential and linear models in a windless environment were 9.8% (Exp) and 18.7% (Lin), respectively. The estimation errors of both models were positively correlated with both the time of a single monitoring event and the wind-induced coefficient Dw. Therefore, flux calculation models should be improved by considering environments with wind disturbances to reduce the effect of wind on measured values, which will help improve the accuracy of ecosystem carbon budgets.