Reduction Zone Research Articles

The Key Controlling Factors and Mechanisms for the Formation of Sandstone-Type Uranium Deposits in the Central Part of the Ulanqab Depression, Erlian Basin

The characteristics of interlayer oxidation zones constrain sandstone-type uranium mineralization. This study conducted a quantitative characterization of the interlayer oxidation zones in the uranium-bearing reservoir of the Saihan Formation in the central Wulanchabu Subbasin of the Erlian Basin through sand dispersion system mapping, the analysis of sedimentary debris components, environmentally sensitive parameters, and elemental geochemical characteristics. The formation mechanisms and controlling factors of interlayer oxidation zones were investigated, along with uranium mineralization patterns. Research findings reveal that the sandbodies in the study area primarily consist of red sandstone, yellow sandstone, gray ore-bearing sandstone, and primary gray sandstone, representing strong oxidation zones, weak oxidation zones, transitional zones, and reduction zones, respectively. Although the mineral debris content shows minimal variation among different zones, feldspar dissolution is more prevalent in oxidized zones. During interlayer oxidation, environmentally sensitive parameters exhibit an ascending trend from strong oxidation zones through weak oxidation zones and reduction zones to mineralized transitional zones. Four transition metal elements (Co, Ni, Zn, and Mo) demonstrate enrichment in mineralized transitional zones. The development of interlayer oxidation zones is directly controlled by reservoir heterogeneity and sedimentary environments. Oxidation subzones primarily occur in sandbodies with moderate thickness (40–80 m), sand content ratios of 40%–80%, and 2–10 or 10–18 mudstone barriers (approximately 20 m thick), mainly in braided river channels and channel margin deposits. Reduction zones develop in thicker sandbodies (~100 m) with higher sand contents (~80%), fewer mudstone barriers (2–8 layers), greater thickness (40–80 m), and predominantly channel margin deposits. Transitional zones mainly occur in braided distributary channels and floodplain deposits. When oxygen-bearing uranium fluids infiltrate reservoirs, oxygen reacts with reductants like organic matter, whereFe2+ oxidizes to Fe3+, S2− reacts with oxygen, and U4+ oxidizes to U6+, migrating as uranyl complexes. As oxygen depletes, Fe3+ reduces to Fe2+, combining with S2− to form pyrite between mineral grains. Uranyl complexes reduce to precipitate as pitchblende, while some U4+ reacts with SiO44−, forming coffinite, occurring as colloids around quartz debris or pyrite. The concurrent enrichment of certain transition metal elements occurs during this process.

Multifunctional cotton wound dressings enhanced with bitter apple fruit extract-loaded solid lipid nanoparticles for antimicrobial, antioxidant, and anticancer activities.

Multifunctional cotton wound dressings enhanced with bitter apple fruit extract-loaded solid lipid nanoparticles for antimicrobial, antioxidant, and anticancer activities.

Tracing organoclastic sulfate reduction within the sulfate-methane transition zone: Petrographic and in situ sulfur isotope evidence from Early Silurian nodules

As the terminal zone for marine sulfate reduction, the sulfate-methane transition zone (SMTZ) drives anaerobic oxidation of methane coupled with sulfate reduction (AOM-SR), linking the carbon and sulfur biogeochemical cycles. This process indirectly influences the redox balance of surface geological environments. To investigate the biogeochemical characteristics within paleo-SMTZs, we examined two representative Early Silurian period nodules from South China. The diagenetic barite and 34S-enriched euhedral pyrite within these nodules indicate a close association with the SMTZ. Sedimentary microtextures reveal the authigenic growth sequence of framboidal pyrite, and significant δ34Spyr heterogeneity suggests a multistage formation for these nodules. In Type-1 nodules, δ34Spyr content at the edges is as low as 8.6‰—significantly less than the 18.8‰ observed at the centers. At the grain scale, the δ34S within individual pyrite grains ranges from −1.9‰ to 29.1‰. We propose that the formation of Type-1 nodules occurred in three stages: (1) Nodule embryos with 34S-depleted pyrite edges formed in the sulfate reduction zone via a diffusion-precipitation model. (2) Within the SMTZ, barite underwent dissolution and reprecipitation, fostering nodule growth by forming large diagenetic barite. Meanwhile, AOM−SR reduced both the residual 34S-enriched sulfate pool near the top of the SMTZ and sulfate released from dissolving barite, producing 34S-enriched, euhedral pyrite. (3) Below the SMTZ, sulfate depletion led to extensive replacement of barite by other minerals. The pronounced concentric structure in Type-2 nodules indicates multiple episodes of formation. The initial stage resembles that of Type-1 nodules, while needle-shaped minerals at the edges formed in response to vertical shifts within the SMTZ. Additionally, calcite, which is commonly associated with the SMTZ, is notably rare within these nodules. Instead, quartz replaces calcite as the nodule matrix and commonly undergoes pseudomorphic replacement of barite. We suggest that the substantial enrichment of quartz relative to calcite within nodules arises from microbial activity that alters pore-water pH and alkalinity, and serves as a petrographic imprint of organoclastic sulfate reduction within paleo-SMTZs.

Spatiotemporal patterns and environmental determinants of wildlife-vehicle collisions in Banke National Park, Nepal

Wildlife vehicle collisions (WVCs) represent a significant threat globally to biodiversity conservation, driver safety and economic resources. This study evaluated the magnitude, spatial-temporal patterns, and influencing factors associated with WVCs within Banke National Park (BaNP), Nepal, to inform effective mitigation planning and biodiversity conservation strategies. Data on WVCs and relevant environmental and anthropogenic variables were collected between April 2015 and March 2024 along a 97.3 km road segment traversing BaNP. The methodological approach integrated field surveys, spatial analyses using kernel density estimation, and statistical modelling to pinpoint collision hotspots and elucidate contributing factors. In total, 488 WVC incidents were documented, predominantly involving mammals (87.52%), followed by reptiles (8.58%) and birds (3.88%). Endangered and vulnerable species, including the golden monitor lizard, leopard cat, and four-horned antelope, were among the recorded fatalities. Spatial analysis identified significant WVC hotspots at Muguwa, Obhari, and Khairi, collectively accounting for over 60% of total incidents. Temporal patterns indicated a seasonal peak during autumn (30%), coinciding with increased post-monsoon dispersal and foraging behaviour. Statistical analyses highlighted that road curvature, proximity to water sources, and surrounding land use significantly influenced collision risk. Specifically, higher WVC odds were associated with curved roads and greater distances from settlements, while straighter road segments and higher forest canopy coverage near roads correlated with reduced risk. This study underscores the pressing need for targeted mitigation measures, such as wildlife crossings, speed reduction zones, and enhanced public awareness initiatives, to reduce WVC occurrences and protect vulnerable wildlife in BaNP. The findings contribute to the existing knowledge regarding road ecology and provide crucial insights for informed conservation interventions within protected areas.

In-situ partial reduction of biochar by overlaying a syngas stream.

In-situ partial reduction of biochar by overlaying a syngas stream.

ANTIBACTERIAL POTENTIALS OF ALOE BARBADENSIS MILLER AND CITRUS LIMON PLANT EXTRACTS AGAINST SKIN INFECTING PROPIONIBACTERIUM ACNES: BOTH IN-VITRO AND IN-VIVO ATTEMPTS

Background: Acne vulgaris is a chronic skin condition that significantly affects facial aesthetics and psychological well-being. It is primarily caused by Propionibacterium acnes, a Gram-positive anaerobic bacterium residing in the pilosebaceous units. The increasing resistance of P. acnes to conventional antibiotics has led to reduced treatment efficacy and rising healthcare costs. As a result, attention has shifted toward herbal therapies that offer safer, cost-effective, and environmentally friendly alternatives. Among the various botanicals, Aloe vera and Citrus lemon have shown promising antimicrobial properties and are widely used in traditional medicine. Objective: This study aimed to evaluate the antibacterial effects of Aloe vera and Citrus lemon extracts against P. acnes using both in-vitro and in-vivo experimental models. Methods: Leaves of Aloe vera and fruits of Citrus lemon were collected from District Bannu. Methanolic and aqueous extracts were prepared in concentrations of 40, 60, 80, and 100 µg/ml. In-vitro testing was performed using the agar well diffusion method with Clindamycin as the positive control. In-vivo analysis involved topical application of aqueous extracts on acne lesions across multiple body parts of participants over a seven-day period. Antibacterial effects were evaluated based on the zone of inhibition and percentage reduction in acne. Results: Aloe vera extract showed inhibition zones of 12, 14, 20, and 23 mm at increasing concentrations, while Citrus lemon produced zones of 13, 16, 19, and 21 mm. Combination therapy yielded enhanced inhibition zones of 14, 17, 21, and 24 mm. In-vivo findings revealed a 61% reduction in acne with Aloe vera, 51% with Citrus lemon, and 67% when used in combination. Conclusion: Both Aloe vera and Citrus lemon demonstrated substantial antibacterial activity against P. acnes, with combined use yielding superior results. These findings support further investigation into the phytochemical constituents for potential large-scale therapeutic use.

Petrological and Geochemical Research on the Telaaobao Sandstone–Hosted Uranium Deposit in the North‐Western Ordos Basin, China: Implications of Multiple Sources

ABSTRACTThe newly discovered Telaaobao uranium deposit, hosted within Lower Cretaceous sandstones in the north‐western Ordos Basin, represents a significant new stratigraphic target for uranium exploration. This study offers detailed petrological and geochemical analyses of different types of rocks from the Huanhe Formation, aiming to investigate the factors controlling uranium mineralisation in this deposit. The Huanhe Formation is generally characterised by low to moderate concentrations of total rare earth element (ΣREE) (70–213 ppm) and Y (7.5–30.1 ppm), right‐inclined REE patterns and slightly negative Eu anomalies, which resemble those of the upper continental crust (UCC). The trace element characteristics further reveal that the sedimentary sources have an average composition typical of intermediate‐felsic rocks, with the addition of some old sediments. The U content in sediments is mostly higher than that of the average UCC, even in non‐mineralised rocks from both the oxidised (2.5–58.8 ppm) and reduced zones (2.0–49.6 ppm), indicating that the provenance rocks and the sedimentary strata can serve as enriched uranium sources for the deposit. The Lower Cretaceous strata in the north‐west margin of the Ordos Basin, which were formed in an arid depositional environment and lacked organic matter and other reducing agents, restricted the formation of uranium deposits. Nevertheless, influenced by multiple stages of tectonic activity, the release of deep‐seated reducing fluids, such as oil and gas, greatly enhanced the reducing capacity of the sandstone, creating an extensive green reduction zone. The current development of uranium ore bodies is mainly controlled by the oxidation–reduction transition zone. Additionally, high U (591–4080 ppm) enrichment has also been found in the oxidised zone, where mineralised rocks display distinct petrological and geochemical characteristics from those in the transition zone. These rocks exhibit anomalous increases in REEs (ΣREE = 168–722 ppm), with bell or flat shape REE patterns and high Y concentration (147–866 ppm). These features resemble the uranium minerals that are typically formed in deep‐originated hydrothermal fluids, especially in unconformity‐related uranium deposits. In this case, the hydrothermal fluids may have also introduced uranium into the Telaaobao deposit as a potential source.

Enhancing concrete properties with nano-SiO2 and nano-TiO2: a review

ABSTRACT The incorporation of nanomaterials in concrete has emerged as a promising approach for enhancing mechanical strength and durability. This review provides a comprehensive comparative evaluation of the roles of nano-silica (NS) and nano-titanium (NT) in improving concrete properties, a perspective not extensively covered in prior reviews. The study critically examines the effects of varying dosages of NS and NT on compressive, split tensile, and flexural strength, along with key durability aspects such as resistance to sulfate and chloride attacks, freeze-thaw cycles, and permeability. A distinctive feature of this review is its microstructural analysis, highlighting how NS and NT influence C-S-H gel formation, porosity reduction, and interfacial transition zone (ITZ) densification. Furthermore, the review identifies emerging research gaps, including the synergistic effects of NS and NT with other nanomaterials (graphene and quantum dots), unexplored durability factors, and optimization challenges in practical applications. Additionally, the economic feasibility of NS and NT incorporation is discussed, considering cost-performance trade-offs and potential sustainability benefits. These insights provide a foundation for future advancements in nano-engineered concrete, making this review a valuable resource for researchers and industry professionals seeking to optimize concrete performance through nanotechnology.

МЕЛИОРАТИВНАЯ ЭФФЕКТИВНОСТЬ ЗАЩИТНЫХ ЛЕСНЫХ ПОЛОС РАЗНЫХ КОНСТРУКЦИЙ, ФУНКЦИОНИРУЮЩИХ ВДОЛЬ ЖЕЛЕЗНЫХ ДОРОГ СВЕРДЛОВСКОЙ ОБЛАСТИ

В статье приведены результаты оценки мелиоративной эффективности двух систем защитных насаждений, функционирующих в полосах отвода Свердловской железной дороги. Каждая система включают две защитные лесные полосы (ЗЛП), расположенные по обеим сторонам от дороги на одинаковом удалении от нее. В первой из них полосы имеют непродуваемую конструкцию, во второй – ажурную. Установлено, что степень и характер отложения снега вдоль дорог существенным образом зависят от конструкции полос в системе. В зоне мелиоративного влияния первой системы наибольшее количество снега задерживается перед полосой и внутри самой полосы, расположенной с наветренной стороны в отношении метелевых ветров. Вследствие этого в непосредственной близости к дороге толщина снежного покрова значительно меньше (в 1,64 раза), чем на контрольном участке. В зоне мелиоративного влияния второй системы снежный покров распределяется с заметно меньшим варьированием по высоте, более равномерно. Здесь глубина снега у железнодорожного полотна только в 1,2 меньше, чем на контрольном участке. Исследуемые системы ЗЛП по-разному изменяют скорость и траекторию ветрового по- тока. Ширина зоны эффективного снижения скорости ветра на объекте с системой непродуваемых полос составляет около 300 м, а на объекте с ажурными полосами в 1,5 раза меньше – 200 м. В зоне мелиоративного влияния и первой и второй систем ЗЛП скорость ветра наименьшее значение имеет в непосредственной близости от дороги с заветренной стороны. Однако степень снижения скорости ветрового потока непродуваемыми полосами в этом месте (50,0 %) значительно выше, чем ажурными (37,5 %). В целом в полосе отвода железной дороги снегозадерживающая и ветроослабляющая эффективность системы защитных насаждений с лесными полосами непродуваемой конструкции заметно выше, чем с полосами ажурной конструкции. The paper presents the results of reclamation efficiency assessment of two systems of protective plantations functioning in the right-of-way of the Sverdlovsk railroad. Each system includes two protective forest strips (PFS) located on both sides of the road at an equal distance from it. In the first of them the strips have an impervious design, in the second – openwork. It was found that the degree and character of snow deposition along the roads significantly depend on the design of strips in the system. In the zone of ameliorative influence of the first system, the greatest amount of snow is retained in front of the strip and inside the strip itself, located on the windward side with respect to blizzard winds. As a consequence, in the immediate vicinity of the road, the snow cover thickness is much less (1,64 times) than in the control plot. In the zone of reclamation influence of the second system, the snow cover is distributed with noticeably less variation in height and more evenly. Here the snow depth near the railroad bed is only 1,2 times less than on the control section. The investigated PFS systems vary the speed and trajectory of the wind flow differently. The width of the zone of effective wind speed reduction at the site with the system of non-blown strips is about 300 m, and at the site with openwork strips 1,5 times less – 200 m. In the zone of ameliorative influence of both the first and second systems of ZLD, wind speed has the lowest value in the immediate vicinity of the road from the windward side. However, the degree of wind velocity reduction by non-blown strips in this place (50,0 %), is much higher than by openwork strips (37,5 %). In general, in the railroad right-of-way the snow-retarding and wind-relieving efficiency of the system of protective plantations with forest strips of non-blown design is noticeably higher than with strips of openwork design.

Study on the Optimization of Coal Pillar Width in Goaf-Side Roadway Under the Synergistic Effect of Mining and Seepage

In coal mine roadways excavated along the goaf with water accumulation, the roadway is subjected to the combined effects of water infiltration and multiple stresses from excavation activities, leading to significant deformation and challenges in determining the appropriate coal pillar width. This study, based on the Jianxin Coal Mine 4301 tailgate, utilizes the advanced three-dimensional numerical calculation software FLAC3D 6.0 to develop a comprehensive seepage flow model. By analyzing the distribution of key roadway surrounding rock properties, such as deviatoric stress, plastic zone, and dissipated energy, the influence of coal pillar width on roadway deformation and failure characteristics is systematically investigated. The findings provide novel insights into the roadway stability control under complex geological conditions. Specifically, the results reveal that: (1) When the coal pillar width is less than 9 m, stress concentration zones are observed, fully connected by plastic zones and dissipated energy. For widths exceeding 9 m, the influence of the goaf diminishes, leading to a stress reduction zone within the coal pillar and a shift in dissipated energy density distribution from a penetrating shape to an independent double-core shape. The plastic zones on both the goaf and roadway sides become independent, indicating a transition from an unstable to a stable coal pillar state. (2) Using the Analytic Hierarchy Process (AHP), a zoning control system for the roadway surrounding rock is established, dividing the roadway into three regions: normal support, reinforced support, and special support. Industrial experiments corroborate the simulation results, and on-site monitoring demonstrates that the control measures significantly improve roadway stability. This study presents an innovative approach to the design and control of coal pillars in water-affected mine roadways, offering valuable contributions to both the scientific understanding and practical application of mining engineering in similar geological settings.

Techno-Economic Study of Palm Kernel Shell Biomass Operated on a Engine Diesel Dual Fuel

Abstract The Indonesian government has implemented a carbon emission reduction program for Diesel Power Plants as part of its efforts to achieve Net Zero Emission (NZE) by 2060. The biomass-fueled power plant approach can reduce the use of fossil fuels and minimize carbon emissions. The purpose of this study was to determine the economic value of a dual-fuel diesel power plant with fuel oil and syngas produced through gasification, using dual-fuel diesel engine technology. Gasification process. The gasification used is a multi-stage downdraft gasifier model, with an optimal air ratio variation of 1:7:2 in the pyrolysis, oxidation, and reduction zones. An experiment was conducted on a diesel engine operating at a speed of 3000 rpm and subjected to various loads ranging from 500 Watts to 4500 Watts. The mass flow rate of syngas can be adjusted by opening four valves, and syngas is fed through the intake manifold of the diesel engine. The use of a dual-fuel engine, which combines syngas with biodiesel, can improve thermal efficiency and reduce B35 fuel consumption. This resulted in a reduction in the specific fuel consumption (SFC) value from 0.257 to 0.213 at a load of 3000 watts. Technoeconomic analysis shows that the utilization of this system has the capacity to generate lasting economic benefits, especially when considering environmental factors and accessibility of local resources.

Techno Study of “Waste to Electric” with Woodchip Pellet Feedstock Through Multi-Stage Gasification in Dual Fuel Diesel Engine

Abstract The increasing demand for energy in various sectors means that energy sources can no longer depend on fossil energy sources, the number of which is decreasing. The decline in fossil energy supply has increased the development of environmentally friendly renewable energy sources, such as biomass. The biomass raw material used is woodchips which has the characteristics of water content 8.4%, volatile solid 74.19%, ash content 1.34%, carbon content 16.07%, hydrogen content 0.0479%, nitrogen 0.4372%, carbon monoxide 0.1701%, methane 0.049%, oxygen 0.1622% and a heating value of 3,907 Kcal/kg. Processing biomass into syngas is carried out through a gasification process. Gasification is the process of converting woodchips into syngas in the form of a gas phase using a three-stage gasification method. Furthermore, the syngas is used as fuel in a dual-fuel diesel engine combined with biodiesel fuel. In this research, a 5 kW diesel engine was used as an experimental tool to determine the performance produced by a dual-fuel diesel engine when dual fuel is injected, namely biodiesel and syngas. The gasifier used in the gasification process of woodchips biomass raw materials has the best water ratio characteristics between the pyrolysis, oxidation and reduction zones, namely 1:7:2. The results of tests that have been carried out with an air ratio setting of 1:7:2 can produce the best diesel engine performance with a stable engine speed value of 3000 rpm and the average voltage at each change in load is 250 volts. Load variations for dual-fuel diesel engine testing are carried out from a load of 0 watts to a load of 4,500 watts. With an increase of every 500 watts. The syngas injection method from the gasifier into the combustion chamber uses 1 variation value, namely full opening (100%). Testing with 100% syngas valve opening resulted in higher average values of engine temperature, exhaust gas temperature and oil temperature compared to other openings. Apart from that, the test results of a 5000-watt engine with dual fuel mode (biodiesel and syngas) were scaled up when applied to the Kolaka PLTD engine which has a capacity of 529 kW. From the calculation results, the value of the savings for using diesel fuel on a 529 kW PLTD engine is Rp. 225,900,975 per month. The initial investment cost is IDR. 1,279,068,380. Meanwhile, the annual income is Rp. 2,445,374,002 assuming Capacity Factor (CF 70%). So the Break Event Point (BEP) value is less than 2 years. Apart from that, a decrease in decarbonization value was also produced by utilizing syngas from woodchip biomass as fuel in a dual-fuel engine with a capacity of 529 kW, resulting in 21.25 tonnes of CO2/year or Rp. 637,431.2

Key reaction pathways for NO reduction by NH3 in the reduction zone during ammonia-coal co-firing: A combined experimental and DFT study

Key reaction pathways for NO reduction by NH3 in the reduction zone during ammonia-coal co-firing: A combined experimental and DFT study

Gasification of different biomasses in a concurrent fixed bed reactor: thermodynamics assessment towards its bioenergy potential

Gasification of different biomasses in a concurrent fixed bed reactor: thermodynamics assessment towards its bioenergy potential

Techno-Economic Study of the Use of Refuse-Derived Fuel (RDF) Biomass Waste Conversion into Electricity Using the Three-Stage Gasification Method and Dual Fuel Diesel Engine on Batam Island

Abstract The increasing need for energy has also reduced the availability of fossil fuels so renewable alternative energy is needed. One of the uses of alternative energy that is currently being developed is biomass, one of the developments of biomass into renewable energy can be done through the gasification process. Gasification is the process of converting solid fuels, commonly called Municipal Solid Waste (MSW) which has a water content of 32.08%, volatile solids of 36.09%, ash content of 24.42%, the carbon content of 7.61%, a calorific value of 2,087% can be processed into Biomass Refuse Derived Fuel (RDF) pellets as raw materials for the three-stage gasification process to become syngas as fuel for diesel engines for electricity “Waste to Electric”. In this study, a diesel engine with a dual fuel diesel system was used. The purpose of the diesel engine running with a dual fuel system is to determine the effect of using syngas fuel from gasification with RDF biomass pellets on a diesel engine with a dual fuel system. The dual fuel diesel system is operated using two types of fuel, namely diesel fuel and gas fuel. The gas fuel used is syngas from the gasification of biomass pellets Refuse Derived Fuel (RDF). In the gasification process, the variation of the air ratio is adjusted in the pyrolysis, oxidation, and reduction zones to obtain the most optimal results with the best air ratio at 1:7:2. The comparison of the air ratio from this gasification process can produce the best performance for a diesel engine with a stable engine speed at 3000 rpm, an average voltage at each load change of 246.7 volts. Characterization of the performance of a dual fuel system diesel engine is carried out by testing the diesel engine with a loading variation of 500 watts to 4500 watts with an interval of increasing the loading every 500 watts and variations in the mass flow rate of syngas by adjusting the opening of the syngas valve to the diesel engine. The opening of the syngas valve from the gasifier used is 100%. Testing with a 100% syngas valve opening produces an average value of engine temperature, exhaust gas temperature, and oil temperature that is higher than other percentage variations. Meanwhile, when testing with single fuel mode, the lowest engine temperature, exhaust gas temperature and oil temperature values were produced at each load change. In addition, the results of the syngas test on a 4500 watt engine with dual fuel mode were scaled up if implemented on a Sekupang PLTD engine with a capacity of 4.48 MW. From the calculation results, the value of savings in the use of diesel fuel on the 4.48 MW PLTD engine was Rp. 875,169,082 per month. The initial investment cost is Rp. 11,460,452,687. While the annual income is Rp. 8,028,548,720.64. So that the Break Event Point (BEP) value is obtained for less than 2 years. In addition, a decrease in the decarbonization value was also produced by utilizing syngas from RDF biomass as fuel on a 4.48 MW dual fuel engine operating for 12 hours every day, 1,094.27 tons of CO2/year or Rp. 32,828,087.26.

Laboratory-to-Field Scale Numerical Investigation of Enhanced Oil Recovery Mechanism for Supercritical CO2-Energized Fracturing

This study systematically performs multi-scale numerical investigation of supercritical CO2-energized fracturing, widely employed for enhanced oil recovery (EOR) in tight oil and gas reservoirs. Two distinct models, spanning from core scale to field scale, are designed to explore the diffusion patterns of CO2 into the matrix and its impact on crude oil production at varying scales. The core-scale model employs discrete grid regions to simulate the interaction between fractures and the core, facilitating a comprehensive understanding of CO2 diffusion and its interaction with crude oil. Based on the core-scale numerical model, the wellbore treatment process is simulated, investigating CO2 distribution within the core and its influence on crude oil during the well treatment phase. The field-scale model employs a series of grids to simulate fractures, the matrix, and the treatment zone. Additionally, a dilation model is employed to simulate fracture initiation and closure during CO2 fracturing and production processes. The model explores CO2 diffusion and its interaction with crude oil at different shut-in times and various injection rates, analyzing their impact on cumulative oil production within a year. The study concludes that during shut-in, CO2 continues to diffuse deeper into the matrix until CO2 concentration reaches an equilibrium within a certain range. At the core scale, CO2 penetrates approximately 4 cm into the core after a 15-day shut-in, effectively reducing the viscosity within a range of about 3.5 cm. At the field scale, CO2 diffusion extends up to approximately 4 m, with an effective viscosity reduction zone of about 3 m. Results suggest that, theoretically, higher injection rates and longer shut-in times yield better EOR results. However, considering economic factors, a 20-day shut-in period is preferred. Different injection rates indicate varying fracture conduction capabilities upon gas injection completion.

The Principle and Downhole Testing of Water Injection Exploration in Depleted Reservoirs

Coal mine water hazards are one of the five major natural disasters in mines, and water in depleted areas is the most serious form of water hazard causing casualties. The exploration of depleted areas, especially old tunnels, presents significant challenges, and achieving the required borehole density for exploration in depleted areas is difficult in reality. The authors of this paper previously applied for a patent titled “Water Injection Exploration Method for Depleted Areas Based on Stress Seepage Principle”. In order to theoretically analyze the feasibility of the patented results and validate them in practice, we first analyze the stress distribution and seepage phenomena around the goaf theoretically, construct boreholes underground in Renlou Coal Mine, conducting on-site water injection tests for different zones (depleted areas, old tunnels, and general boreholes), and perform transient electromagnetic observations during the water injection tests. A total of 355 sets of water injection flow rate and pressure data were obtained from different zones in three different boreholes; permeability coefficients were calculated based on the measured data, and relevant diagrams were drawn. Through the analysis of water injection test data and theoretical analysis, the following conclusions were drawn: there are disturbances and stress reduction zones around depleted areas (old tunnels), and when the equivalent normal stress induced by water injection pressure is greater than zero, the permeability of fractures will increase significantly. Whether it is a borehole aimed at depleted areas or old tunnels, it shows the characteristic that the closer the distance to the depleted areas (old tunnels) is, the smaller the water injection pressure, and the larger the permeability coefficient. When water is injected into the disturbance and stress reduction zones of the depleted areas (old tunnels), the water injection pressure can decrease from 9–10 MPa to 3–4 MPa, and the permeability coefficient may even increase in quantity value. The phenomena of pressure reduction and increased permeability during water injection are significantly observable, indicating that the water injection exploration method for depleted areas based on the stress seepage principle is feasible and has practical significance.

Utilization of Cocoa Pod Husk Waste as Fuel for Downdraft Type Gasification Reactor of 960 Liters Capacity in Berau Regency

This experiment aims to investigate the performance characteristics of a downdraft gasification reactor fueled by cocoa pod husk as a technological solution for obtaining alternative renewable energy sources to replace fossil fuels and natural gas. The research was conducted experimentally on a gasification reactor made of SS310 thermal resistant carbon steel material. The reactor has dimensions of 35 centimeter in diameter and 250 centimeter in height. Measurement of gasification zone using 7 units of K-type thermocouples that was installed along the reactor wall. Fuel was feeding continuously at a rate of 4kg/hour. The research was conducted by varying the temperature in oxidation zone, specifically at 900 ºC, 950 ºC, 1000 ºC, 1050 ºC, and 1100 ºC. Data collection was carried out in different temperature variations and processed to determine the performance parameters of the gasification reactor, including gas composition, temperature distribution on the reactor wall, and the lower heating value (LHV) of the syngas production. The results showed the highest temperature distribution of the reactor in the drying zone 205ºC, pyrolysis zone 575ºC and reduction zone 520 ºC that be obtained at the oxidation temperature of 1100 ºC . Meanwhile the optimum value of syngas quality was obtained at the oxidation temperature of 1000 ºC with the composition of flamable syngas CO, H2, and CH4 are 27.08%, 8.53% and 2.41% , with the highest LHV 5206 kJ/m3. In general the increasing of the oxidation temperature lead to a positive contribution to the performance of the gasification reactor using cocoa pod husk waste.

A novel method combining strata movement and UAV infrared remote sensing technology to evaluate mining ground damage

Mining-induced ground fissures are common problems associated with mining damage in shallowly buried coal seams in the western mining area of China. To evaluate the surface mining damage of the 12203 working face of the Huojitu Colliery in Shendong mining area, low-altitude infrared aerial surveys were conducted on the ground at the static fissure area (O-A1) and the dynamic fissure area (O-A2) of the working face. The temperature evolution patterns of fissures, sand and plants in the infrared images were analysed. The relationship between overburden fractures and surface fissure temperature was revealed, and the influence range and temperature self-healing period of the surface affected by underground mining were determined. The results indicated that underground mining could lead to a decrease in the ground temperature above the working face. The surface temperature evolution can be divided into three zones: a temperature stabilization zone before mining, a temperature cooling zone during mining, and a temperature recovery zone after mining. The temperature of sand and plants above the working face exhibited quadratic curve changes in O-A1 and O-A2, respectively. The length of the temperature reduction zone affected by mining is 40 m in O-A2, and 46.8 m in O-A1. The temperature recovery periods of ground fissures in O-A1 and O-A2 were 4.0 and 4.6 d, respectively. These findings could provide a basis for evaluating mining ground damage.

Analysis of Species Concentrations in Bifunctional Air Electrodes Using Mathematical Modeling and Simulation

Metal-air secondary batteries using aqueous alkaline solutions are attracting attention as a next-generation large-scale energy storage system. However, the large overpotential of the bifunctional air electrode is a challenge for its practical application. In order to reduce the overvoltage, one approach is to optimize the design of the electrode to enhance both electrochemical as well as transport properties within. We have previously estimated the oxygen diffusion resistance in bifunctional air electrodes with different thicknesses and electrolyte solutions from the difference in the steady state potential under air and oxygen flow. We identified that the reaction zone for the oxygen reduction and evolution reactions concentrated on the gas and electrolyte sides of the catalyst layer, respectively. 1 On the other hand, it is difficult to analyze local reaction rates in more detail since gas diffusion electrodes have a complex structure with a mixture of solid, gas, and liquid. In this study, we analyzed the local conditions in gas diffusion electrodes by combining digital simulations using finite difference methods and electrochemical measurements. The electrolyte solution's distribution significantly affects the simulation result since the electrolyte solution works as both an ionic conductiont and an obstacle to oxygen transport.2 Therefore, the electrolyte solution distribution in the electrode was determined by impedance analysis using a transmission line model, and a simulation model was constructed based on this impedance analysis.Figure 1 shows the Nyquist plot of a gas diffusion electrode at OCV. A transmission line-type frequency dependency is observed in the high-frequency region. The impedance simulated with an equivalent circuit where the ion transport resistance in the electrode does not change in the thickness direction shows a relatively significant difference from the measured one. On the other hand, the impedance simulated with an equivalent circuit with the linear decrease in the ionic conductance from the electrolyte to gas diffusion layer sides showed good agreement with the measured one. This result indicates that the amount of electrolyte in the gas diffusion electrode decreases from the electrolyte side to the gas diffusion layer side. Simplifying the pore structure with the porosity and average pore size obtained with the Barrett-Joyner-Halenda (BJH) method and the tortuosity calculated from the Bruggeman’s equation, the electrolyte thickness was calculated to be 2.1 and 1.1 nm at the electrolyte and gas sides, respectively. The local conditions in the electrode obtained with a one-dimensional simulation model based on the obtained electrolyte solution distribution will be presented at the site. Acknowledgment This work was financially supported by RP-LEAD with DFG (JPJSJRP20221602 and SCHR 1756/1-1).