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Keywords = bearing-based formation control

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19 pages, 10274 KB  
Article
Source–Reservoir Structure of Member 2 of Xujiahe Formation and Its Control on Differential Enrichment of Tight Sandstone Gas in the Anyue Area, Sichuan Basin
by Hui Long, Tian Gao, Dongxia Chen, Wenzhi Lei, Xuezhen Sun, Hanxuan Yang, Zhipeng Ou, Chao Geng, Chenghai Li, Tian Liu, Qi Han, Jiaxun Lu and Yani Deng
Energies 2026, 19(1), 19; https://doi.org/10.3390/en19010019 - 19 Dec 2025
Viewed by 197
Abstract
Member 2 of the Xujiahe Formation in the Anyue area of the Sichuan Basin exhibits significant resource potential for tight sandstone gas. However, its characteristic of “extensive gas presence with localized enrichment” leads to substantial variations in single-well productivity, challenges in target zone [...] Read more.
Member 2 of the Xujiahe Formation in the Anyue area of the Sichuan Basin exhibits significant resource potential for tight sandstone gas. However, its characteristic of “extensive gas presence with localized enrichment” leads to substantial variations in single-well productivity, challenges in target zone optimization, and unclear enrichment mechanisms, which hinder efficient exploration and development. This study proposes a hierarchical classification scheme of “two-level, six-type” source–reservoir structures based on the developmental characteristics of fault–fracture systems and vertical source–reservoir configurations. The gas-bearing heterogeneity is quantitatively characterized using parameters such as effective gas layer thickness, charge intensity, and effective gas layer probability, thereby revealing the differential enrichment mechanisms of tight sandstone gas controlled by source–reservoir structures. Our key findings include the following: (1) Member 2 of the Xujiahe Formation develops six subtypes of source–reservoir structures grouped into two levels, with gas-bearing capacities ranked as follows: source–reservoir separation type > source–reservoir adjacent type I > source–reservoir adjacent type II. Among these, the source–reservoir separation type (Level I) and fault–fracture conduit type (Level II) represent the most favorable structures for gas enrichment. (2) Tight sandstone gas enrichment is governed by a tripartite synergistic mechanism: hydrocarbon supply from source rocks, vertical cross-layer migration dominated by fault–fracture systems, and reservoir storage capacity determined by fracture density and reservoir thickness. (3) Three enrichment models are established: (i) a strong enrichment model characterized by “multi-layer source rocks beneath the reservoir, cross-layer migration, and thick fractured reservoirs”; (ii) a moderate enrichment model defined by “single-layer source rocks, localized migration, and medium-thick fractured reservoirs”; and (iii) a weak enrichment model featuring “single-layer hydrocarbon supply, pore-throat migration, and thin tight reservoirs.” This research provides a theoretical basis for optimizing exploration targets in Member 2 of the Xujiahe Formation in the Anyue area and offers insights applicable to analogous continental tight gas reservoirs. Full article
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30 pages, 4710 KB  
Article
Island Community-Based Tourism and Gendered Power: How Respectability and Paperwork Organize Women’s Everyday Authority in Phuket, Thailand
by Siyuan Liu and Piya Pangsapa
Tour. Hosp. 2025, 6(5), 281; https://doi.org/10.3390/tourhosp6050281 - 12 Dec 2025
Viewed by 449
Abstract
This study investigates how women at a Muslim island community-based tourism (CBT) site convert performed respectability and routine paperwork into everyday organizational authority. Drawing on four months of ethnographic fieldwork in Bang Rong, Phuket—supported by seventeen semi-structured interviews, three years of social-media observation [...] Read more.
This study investigates how women at a Muslim island community-based tourism (CBT) site convert performed respectability and routine paperwork into everyday organizational authority. Drawing on four months of ethnographic fieldwork in Bang Rong, Phuket—supported by seventeen semi-structured interviews, three years of social-media observation (2023–2025), and analysis of rosters, ledgers, receipts, and LINE threads—the study examines how gendered norms and material devices structure authority in daily tourism practice. The analysis identifies an authorization stack (veil, uniform, tone) and a set of paperwork devices (ledgers, rosters, receipts, digital groups) that make women’s visibility both morally credible and institutionally legible. Using a poststructural feminist lens and Barriteau’s gender-system framework, the article develops an interpretive, case-derived Respectability-in-Action Conversion Model, showing that moral credit converts into procedural authority only when respectability cues align with control of at least one device. Conversion, however, remains partial and contingent: strategic levers stay largely male or mosque-adjacent unless women obtain rights-bearing tools, such as co-signature authority, petty-cash control, or platform access, along with institutional protection against sanction. Age, class, and endorsement shape these trajectories, enabling some women to consolidate authority while rendering others easily replaceable. The study contributes: (1) a case-specific, empirically grounded account of authority formation in island CBT; (2) an analytic lens for understanding how performance, devices, and rights interact in this setting; and (3) practice-oriented implications for small-island CBT contexts that emphasize shared device access, rotating administrative duties, co-signature and budget rights, and safeguards against organizational capture. Full article
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51 pages, 4171 KB  
Review
Brick by Brick the Wall Is Being Built: Particle-Based Scaffolds for Regenerative Medicine
by Viktor Korzhikov-Vlakh, Lei Wang, Sofia Morozova, Ekaterina Sinitsyna, Tatiana Tennikova and Evgenia Korzhikova-Vlakh
Polymers 2025, 17(23), 3227; https://doi.org/10.3390/polym17233227 - 4 Dec 2025
Viewed by 465
Abstract
Tissue engineering offers a promising solution by developing scaffolds that mimic the extracellular matrix and guide cellular growth and differentiation. Recent evidence suggests that scaffolds must provide not only biocompatibility and appropriate mechanical properties, but also the structural complexity and heterogeneity characteristic of [...] Read more.
Tissue engineering offers a promising solution by developing scaffolds that mimic the extracellular matrix and guide cellular growth and differentiation. Recent evidence suggests that scaffolds must provide not only biocompatibility and appropriate mechanical properties, but also the structural complexity and heterogeneity characteristic of natural tissues. Particle-based scaffolds represent an emerging paradigm in regenerative medicine, wherein micro- and nanoparticles serve as primary building blocks rather than minor additives. This approach offers exceptional control over scaffold properties through precise selection and combination of particles with varying composition, size, rigidity, and surface characteristics. The presented review examines the fundamental principles, fabrication methods, and properties of particle-based scaffolds. It discusses how interparticle connectivity is achieved through techniques such as selective laser sintering, colloidal gel formation, and chemical cross-linking, while scaffold architecture is controlled via molding, templating, cryogelation, electrospinning, and 3D printing. The resulting materials exhibit tunable mechanical properties ranging from soft injectable gels to rigid load-bearing structures, with highly interconnected porosity that is essential for cell infiltration and vascularization. Importantly, particle-based scaffolds enable sophisticated pharmacological functionality through controlled delivery of growth factors, drugs, and bioactive molecules, while their modular nature facilitates the creation of spatial gradients mimicking native tissue complexity. Overall, the versatility of particle-based approaches positions them as prospective tools for tissue engineering applications spanning bone, cartilage, and soft tissue regeneration, offering solutions that integrate structural support with biological instruction and therapeutic delivery on a single platform. Full article
(This article belongs to the Special Issue Polymer Scaffolds for Tissue Engineering, 3rd Edition)
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15 pages, 4041 KB  
Article
Bearing-Based Formation Control of Multi-UAV Systems with Conditional Wind Disturbance Utilization
by Qin Wang, Yuhang Shen, Yanmeng Zhang and Zhenqi Pan
Actuators 2025, 14(12), 586; https://doi.org/10.3390/act14120586 - 2 Dec 2025
Viewed by 311
Abstract
This paper investigates bearing-based formation control of multiple unmanned aerial vehicles (UAVs) flying in low-altitude wind fields. In such environments, time-varying wind disturbances can distort the formation geometry, enlarge bearing errors, and even induce potential collisions among neighboring UAVs, yet they also contain [...] Read more.
This paper investigates bearing-based formation control of multiple unmanned aerial vehicles (UAVs) flying in low-altitude wind fields. In such environments, time-varying wind disturbances can distort the formation geometry, enlarge bearing errors, and even induce potential collisions among neighboring UAVs, yet they also contain components that can be beneficial for the formation motion. Conventional disturbance compensation methods treat wind as a purely harmful factor and aim to reject it completely, which may sacrifice responsiveness and energy efficiency. To address this issue, we propose a pure bearing-based formation control framework with Conditional Disturbance Utilization (CDU). First, a real-time disturbance observer is designed to estimate the wind-induced disturbances in both translational and rotational channels. Then, based on the estimated disturbances and the bearing-dependent potential function, CDU indicators are constructed to judge whether the current disturbance component is beneficial or detrimental with respect to the formation control objective. These indicators are embedded into the bearing-based formation controller so that favorable wind components are exploited to accelerate formation convergence, whereas adverse components are compensated. Using an angle-rigid formation topology and a Lyapunov-based analysis, we prove that the proposed CDU-based controller guarantees global asymptotic stability of the desired formation. Simulation results on triangular and hexagonal formations under complex wind disturbances show that the proposed method achieves faster convergence and improved responsiveness compared with traditional disturbance observer-based control, while preserving formation stability and safety. Full article
(This article belongs to the Section Aerospace Actuators)
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35 pages, 6556 KB  
Review
Artificial Intelligence-Guided Pulsed Synthesis of Zinc Oxide Nanostructures on Thin Metal Shells
by Serguei P. Murzin
Processes 2025, 13(11), 3755; https://doi.org/10.3390/pr13113755 - 20 Nov 2025
Viewed by 763
Abstract
Zinc oxide (ZnO) nanostructures have been intensively investigated for applications in sensing, photocatalysis, and optoelectronic devices, where functional performance is strongly governed by morphology, crystallinity, and defect structure. Conventional wet-chemical and vapor-phase growth methods often require long processing times or complex chemistries and [...] Read more.
Zinc oxide (ZnO) nanostructures have been intensively investigated for applications in sensing, photocatalysis, and optoelectronic devices, where functional performance is strongly governed by morphology, crystallinity, and defect structure. Conventional wet-chemical and vapor-phase growth methods often require long processing times or complex chemistries and face reproducibility and compatibility challenges when applied to thin, flexible, or curved metallic substrates. Pulsed high-energy techniques—such as pulsed laser deposition (PLD), high-power impulse magnetron sputtering (HiPIMS), and pulsed laser or plasma processing—offer a versatile alternative, enabling rapid and localized synthesis both from and on Zn-bearing thin shells. These methods create transient nonequilibrium conditions that accelerate oxidation and promote spatially controlled nanostructure formation. This review highlights the emerging integration of artificial intelligence (AI) with pulsed ZnO synthesis on thin metallic substrates, emphasizing standardized data reporting, Bayesian optimization and active learning for efficient parameter exploration, physics-informed and graph-based neural networks for predictive modeling, and reinforcement learning for adaptive process control. By connecting synthesis dynamics with data-driven modeling, the review outlines a path toward predictive and autonomous control of ZnO nanostructure formation. Future perspectives include autonomous experimental workflows, machine-vision-assisted diagnostics, and the extension of AI-guided pulsed synthesis strategies to other functional metal oxide systems. Full article
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24 pages, 18514 KB  
Article
Development of a Bearing-Based Distributed Control Method for UAV Formation Tracking and Obstacle Avoidance
by Jaewan Choi and Younghoon Choi
Aerospace 2025, 12(11), 1013; https://doi.org/10.3390/aerospace12111013 - 13 Nov 2025
Viewed by 434
Abstract
Unmanned Aerial Vehicles (UAVs) are playing an increasingly vital role in modern battlefields. Accordingly, considerable research has been devoted to Manned–Unmanned Teaming (MUM-T) systems, with formation flight recognized as a key enabling technology for coordinating multiple UAVs. In MUM-T operations, leader–follower formations are [...] Read more.
Unmanned Aerial Vehicles (UAVs) are playing an increasingly vital role in modern battlefields. Accordingly, considerable research has been devoted to Manned–Unmanned Teaming (MUM-T) systems, with formation flight recognized as a key enabling technology for coordinating multiple UAVs. In MUM-T operations, leader–follower formations are commonly employed, while distributed formation methods have gained increasing attention owing to their stability and scalability. Among these, bearing-based control provides unique advantages for managing dynamic formations involving scaling and rotation. However, conventional bearing-based approaches typically require multiple leaders and encounter inherent limitations in flexibly handling obstacle avoidance. To address these challenges, this study proposes a hierarchical bearing-based leader–follower formation system comprising a single leader and multiple follower UAVs. By introducing the concept of virtual leaders, the proposed method enables the construction of formations with only one leader, thereby simplifying the system architecture while preserving scalability. In addition, a novel obstacle-avoidance strategy is developed, allowing followers to avoid collisions efficiently while maintaining formation integrity. The effectiveness of the proposed framework is demonstrated through numerical simulations of representative formation patterns, including V-shaped and hexagonal configurations, in obstacle-rich environments. The results confirm that follower UAVs successfully tracked the leader, preserved the designated formation, and achieved effective obstacle avoidance, thereby validating the stability and robustness of the proposed approach. Full article
(This article belongs to the Section Aeronautics)
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21 pages, 10039 KB  
Article
The Discovery of MVT-like Ga-Enriched Sphalerite from the Zhaojinci Area in the South Hunan District (South China)
by Feiyun Xiao, Hongjie Shen, Qingrui He, Shihong Huang, Xiaoxi Liu and Yu Zhang
Minerals 2025, 15(11), 1163; https://doi.org/10.3390/min15111163 - 4 Nov 2025
Viewed by 392
Abstract
Gallium (Ga) enrichment in sphalerite has been widely recognized; however, its enrichment mechanisms remain insufficiently understood. The South Hunan district, located at the intersection of the Nanling Region and the Qin-Hang Metallogenic Belt in South China, is characterized by abundant Jurassic magmatic-hydrothermal Pb–Zn [...] Read more.
Gallium (Ga) enrichment in sphalerite has been widely recognized; however, its enrichment mechanisms remain insufficiently understood. The South Hunan district, located at the intersection of the Nanling Region and the Qin-Hang Metallogenic Belt in South China, is characterized by abundant Jurassic magmatic-hydrothermal Pb–Zn deposits, which typically host Ga-depleted sphalerite. Recently, Ga-enriched sphalerite (up to 385 ppm by LA-ICP-MS) has been identified in newly drilled cores at Zhaojinci, adding complexity to the regional Pb–Zn metallogenic framework. EPMA elemental mapping and LA-ICP-MS time-resolved spectra indicate that Ga is homogeneously distributed within sphalerite, excluding the presence of micron-scale Ga-bearing mineral inclusions. A strong positive correlation between Ga and Cu concentrations suggests that Ga incorporation is facilitated by the coupled substitution of Zn2+ by Cu+. Sphalerite geothermometry yields formation temperatures of 118–138 °C (average 126 °C for GGIMF is and ~129 °C for SPRFT), accompanied by intermediate sulfur fugacity conditions (lg fS2 = −22.9 to −21.2), which appear to favor Ga enrichment in sphalerite. The trace element geochemistry of the Zhaojinci sphalerite (Ga-Ge-Cd-enriched and Mn-In-Sn-Co-depleted), combined with its formation under low-temperature (120–180 °C) and intermediate fS2 conditions (within the pyrite stability field), is consistent with MVT-like mineralization. This interpretation is supported by multiple lines of geological evidence, including the strict confinement of stratabound Pb–Zn mineralization to the Devonian Xikuangshan Formation limestone, structural control by syn-sedimentary normal faults, pervasive dolomitization of the host rocks, and the absence of genetic relationship to magmatic activity. Moreover, the sphalerite geochemical signature, corroborated by an XGBoost-based machine learning classifier, reinforce the MVT-like affinity for the Zhaojinci mineralization. This study not only emphasizes the importance of low-temperature and intermediate-fS2 conditions in Ga enrichment within sphalerite, but also highlights the significance of discovering MVT-like sphalerite for Pb–Zn resource exploration in the South Hunan district, providing valuable new insights and directions for mineral prospecting in this geologically important region of South China. Full article
(This article belongs to the Section Mineral Exploration Methods and Applications)
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11 pages, 2538 KB  
Article
Enabling Ultra-Stable Bearing Performance: Design of a Self-Lubricating PI Composite Retainer
by Zhining Jia and Caizhe Hao
Lubricants 2025, 13(11), 465; https://doi.org/10.3390/lubricants13110465 - 23 Oct 2025
Viewed by 505
Abstract
To address challenges such as temperature rise, operational instability, and premature failure in rolling bearings caused by retainer friction, this study designed and developed a high-performance polyimide (PI)-based composite self-lubricating retainer to enable “ultra-stable” bearing operation. Both solid and oil-porous self-lubricating retainers were [...] Read more.
To address challenges such as temperature rise, operational instability, and premature failure in rolling bearings caused by retainer friction, this study designed and developed a high-performance polyimide (PI)-based composite self-lubricating retainer to enable “ultra-stable” bearing operation. Both solid and oil-porous self-lubricating retainers were fabricated through material composition and structural design. Systematic tests under controlled load and speed conditions were conducted to compare their temperature rise behavior and wear morphology. The results demonstrated that the temperature rise in the YSU-PI1 bearing with a solid retainer decreased by approximately 57% compared to a conventional bearing. The YSU-PA2 bearing with an oil-porous retainer exhibited a further improvement in thermal performance. Notably, under high-speed conditions, the equilibrium temperature of the YSU-PA2 bearing was lower than that under low-speed conditions, confirming a centrifugal-force-driven self-regulating oil-supply mechanism. Wear surface analysis revealed that the porous structure promoted the formation of a continuous and uniform transfer film, effectively mitigating wear and pitting. This study successfully integrates “material–structure–function” innovation. The oil-porous PI-based composite retainer transforms centrifugal force—typically considered detrimental—into a beneficial lubrication mechanism, effectively suppressing temperature rise and enabling “ultra-stable operation”. These findings provide crucial theoretical and technical support for developing bearings for high-end equipment. Full article
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31 pages, 20777 KB  
Article
Depositional Processes and Paleoenvironmental Evolution of the Middle Eocene Lacustrine Shale in Beibu Gulf Basin, South China
by Chengkun Deng, Yifan Li, Zhiqian Gao, Juye Shi, Ruisi Li, Ruoxin Huang, Guocui Li and Xinsheng Wen
Appl. Sci. 2025, 15(20), 11191; https://doi.org/10.3390/app152011191 - 19 Oct 2025
Viewed by 2406
Abstract
This study focuses on the middle Eocene lacustrine shales of the Lower Member 2 of the Liushagang Formation (L–LS2) in the Weixi’nan Depression of the Beibu Gulf Basin. Employing an integrated approach that combines core observation, thin-section analysis, Scanning Electron Microscopy (SEM), X-ray [...] Read more.
This study focuses on the middle Eocene lacustrine shales of the Lower Member 2 of the Liushagang Formation (L–LS2) in the Weixi’nan Depression of the Beibu Gulf Basin. Employing an integrated approach that combines core observation, thin-section analysis, Scanning Electron Microscopy (SEM), X-ray Diffraction (XRD), and geochemical proxies, we systematically characterize the lithofacies, sedimentary processes, and paleoenvironmental evolution. Six distinct lithofacies were identified: clay-rich mudstone, calcium-bearing mudstone, clay-rich siltstone, siliceous siltstone, ankerite-bearing sandstone, and siliceous sandstone. Based on depositional processes and structural features, these are grouped into three lithofacies assemblages: interbedded lithofacies assemblage, laminated lithofacies assemblage, and matrix lithofacies assemblage. Vertical facies distribution shows that the interbedded lithofacies assemblage dominates the lower L–LS2, reflecting active faulting, volcanism, a low lake level, prevalent gravity flows, and episodic oxidative conditions. The laminated lithofacies assemblage dominates the middle section and results from the combined influence of chemical and mechanical deposition, indicating fluctuating climate conditions that affected water depth, salinity, and redox dynamics. The upper section is characterized by matrix lithofacies assemblage, representing a stable, deep water, anoxic environment with low energy suspension settling. We propose a depositional model in which tectonics and climate jointly control lacustrine shale deposition. During the middle Eocene, intensified tectonic activity expanded accommodation space and increased clastic input, while climate fluctuations influenced chemical weathering, nutrient supply, and salinity. Together, these factors drove lake deepening and variability, affecting sedimentary energy and redox conditions. This study not only clarifies the sedimentary evolution of L–LS2 but also provides a critical geological framework for lacustrine shale oil exploration. Full article
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14 pages, 1536 KB  
Article
Experimental Constraints on Baryte–Sulfide Ore in the Miocene Seawater-Dominated Mykonos Vein System, Cyclades
by Maria Tsirigoti, Ioannis Koukouvelas, Alkiviadis Sideridis, Joan Papavasiliou and Stylianos Tombros
Minerals 2025, 15(10), 1012; https://doi.org/10.3390/min15101012 - 24 Sep 2025
Viewed by 547
Abstract
This study presents experimental and geochemical modeling results that validate a fluid-mixing model for baryte and sulfide mineralization in vein-type hydrothermal systems, with reference to the Mykonos granodiorite, Cyclades. Synthetic Ba-rich hydrothermal fluids, representing those released during retrograde alteration of granitoids, were mixed [...] Read more.
This study presents experimental and geochemical modeling results that validate a fluid-mixing model for baryte and sulfide mineralization in vein-type hydrothermal systems, with reference to the Mykonos granodiorite, Cyclades. Synthetic Ba-rich hydrothermal fluids, representing those released during retrograde alteration of granitoids, were mixed with SO42−-bearing solutions, simulating Miocene seawater under controlled conditions (200–300 °C, <100 bars). Baryte precipitated rapidly upon mixing, accompanied by the co-precipitation of sulfides, such as sphalerite, chalcopyrite, galena, and minor native silver. The experiments reproduced key mineral assemblages observed in the Mykonos vein system, emphasizing the importance of a second fluid boiling at 250 °C, and redox shifts as triggers for ore formation. Complementary geochemical simulations (Solveq) constrained the stability fields of Ba–sulfate and base-metal sulfides, highlighting the critical influence of pH (5.0–6.2) and SO42−/H2S ratios on mineral precipitation. The integration of experimental and simulation approach supports a robust model for baryte–sulfide deposition in shallow, extensional settings, where fault-controlled fluid flow promotes episodic mixing and boiling of magmatic and seawater-derived ore fluids. Full article
(This article belongs to the Section Mineral Deposits)
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13 pages, 2592 KB  
Article
Reduction Study of Carbon-Bearing Briquettes in the System of Multiple Reductants
by Xiaojun Ning, Zheng Ren, Nan Zhang, Guangwei Wang, Xueting Zhang, Junyi Wu, Jiangbin Liu, Andrey Karasev and Chuan Wang
Materials 2025, 18(18), 4408; https://doi.org/10.3390/ma18184408 - 21 Sep 2025
Cited by 1 | Viewed by 593
Abstract
Against the backdrop of escalating global carbon emissions, the steel industry urgently requires a transition toward green and low-carbon practices. As a conditionally carbon-neutral renewable energy source, biochar holds potential for replacing traditional fossil-based reducing agents. This study aims to investigate the mechanism [...] Read more.
Against the backdrop of escalating global carbon emissions, the steel industry urgently requires a transition toward green and low-carbon practices. As a conditionally carbon-neutral renewable energy source, biochar holds potential for replacing traditional fossil-based reducing agents. This study aims to investigate the mechanism and performance differences between biochar (wood char, bamboo char) and conventional reducing agents (semi-coke, coke powder, anthracite) in the direct reduction process of carbon-bearing briquettes. Through reduction experiments simulating rotary kiln conditions, combined with analysis of reducing agent gasification characteristics, carbon-to-oxygen (C/O) molar ratio control, X-ray diffraction (XRD), and microstructural examination, the high-temperature behavior of different reducing agents was systematically evaluated. Results indicate that biochar exhibits superior gasification reactivity due to its high specific surface area and developed pore structure: wood char and bamboo char show significantly enhanced reaction rates above 1073 K, approaching complete conversion at 1173 K. In contrast, anthracite and coke powder, characterized by dense structures and low specific surface areas, failed to achieve complete gasification even at 1273 K. Pellets containing bamboo char achieved the highest metallization rate (90.16%) after calcination at 1373 K. The compressive strength of the pellets first decreased and then increased with rising temperature, consistent with the trend in metallization rate. The mechanism analysis indicates that the high reactivity and porous structure of biochar promote rapid CO diffusion and synergistic gas–solid reactions, significantly accelerating the reduction of iron oxides and the formation of metallic iron. Full article
(This article belongs to the Special Issue Advances in Process Metallurgy and Metal Recycling)
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29 pages, 9860 KB  
Article
The Source and Evolution of Ore-Forming Fluids in the Xiaobaihegou Fluorite Deposit, Altyn-Tagh Orogen, NW China: Constraints from Trace Element, Fluid Inclusion, and Isotope Studies
by Kang Chen, Wenlei Song, Yuanwei Wang, Long Zhang, Yongkang Jing, Yi Zhang, Yongbao Gao, Ming Liu, Nan Deng and Junwei Wu
Minerals 2025, 15(8), 840; https://doi.org/10.3390/min15080840 - 8 Aug 2025
Viewed by 890
Abstract
The Xiaobaihegou fluorite deposit is located in the southwest of the Altyn-Tagh Orogen, NW China. However, the provenance, thermodynamic properties, and enrichment mechanisms of the ore-forming fluids in this deposit remain unclear. Fluorite mineralization primarily occurs in the vicinity of the contact zone [...] Read more.
The Xiaobaihegou fluorite deposit is located in the southwest of the Altyn-Tagh Orogen, NW China. However, the provenance, thermodynamic properties, and enrichment mechanisms of the ore-forming fluids in this deposit remain unclear. Fluorite mineralization primarily occurs in the vicinity of the contact zone between the granite and the wall rocks. The zircon U-Pb age of the alkali-feldspar granite in the Xiaobaihegou fluorite deposit is 482.3 ± 4.1 Ma. The ore-hosting lithologies are mainly calcareous rock series of the Altyn Group. The ore bodies are controlled by NE-trending faults and consist primarily of veined, brecciated, massive, and banded ores. The ore mineral assemblage is primarily composed of calcite and fluorite. The rare earth element (REE) patterns of fluorite and calcite in the Xiaobaihegou deposit exhibit right-dipping LREE enrichment with distinct negative Eu anomalies, which closely resemble those of the alkali-feldspar granite. This similarity suggests that the REE distribution patterns of fluorite and calcite were likely inherited from the pluton. The ore-forming process can be divided into an early stage and a late stage. The massive ores formed in the early stage contain mainly gas-rich two-phase fluid inclusions and CO2-bearing three-phase inclusions, with homogenization temperatures ranging from 235 °C to 426 °C and salinities from 28.59% to 42.40% NaCl equivalent. In the late stage, brecciated and stockwork ores were formed. They host liquid-rich two-phase and gas-rich two-phase fluid inclusions, with homogenization temperatures ranging from 129 °C to 350 °C and salinities from 0.88% to 21.61% NaCl equivalent. The results of hydrogen and oxygen isotope studies indicate that the ore-forming fluids were derived from a mixture of magmatic–hydrothermal and meteoric water. Fluorite precipitation in the early stage was mainly due to the mixing of magmatic–hydrothermal solution and meteoric water, as well as a water–rock reaction. In the late stage, fluid mixing further occurred, resulting in a decrease in temperature and the formation of brecciated and stockwork ores. The 87Sr/86Sr and 143Nd/144Nd ratios of fluorite from the deposit range from 0.71033 to 0.71272 and 0.511946 to 0.512073, respectively, indicating that the ore-forming material originates from the crust. Based on the ore-forming characteristics, it is proposed that Ca may be primarily leached from the strata formation, while F may predominantly originate from magmatic–hydrothermal solutions. The formation of fluorite deposits is closely related to the transition of the Central Altyn-Tagh Block and Qaidam Block from a compressional orogenic environment to an extensional tectonic environment. Full article
(This article belongs to the Section Mineral Deposits)
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17 pages, 6856 KB  
Article
Selection of Optimal Parameters for Chemical Well Treatment During In Situ Leaching of Uranium Ores
by Kuanysh Togizov, Zhiger Kenzhetaev, Akerke Muzapparova, Shyngyskhan Bainiyazov, Diar Raushanbek and Yuliya Yaremkiv
Minerals 2025, 15(8), 811; https://doi.org/10.3390/min15080811 - 31 Jul 2025
Viewed by 679
Abstract
The aim of this study was to improve the efficiency of in situ uranium leaching by developing a specialized methodology for selecting rational parameters for the chemical treatment of production wells. This approach was designed to enhance the filtration properties of ores and [...] Read more.
The aim of this study was to improve the efficiency of in situ uranium leaching by developing a specialized methodology for selecting rational parameters for the chemical treatment of production wells. This approach was designed to enhance the filtration properties of ores and extend the uninterrupted operation period of wells, considering the clay content of the productive horizon, the geological characteristics of the ore-bearing layer, and the composition of precipitation-forming materials. The mineralogical characteristics of ore and precipitate samples formed during the in situ leaching of uranium under various mining and geological conditions at a uranium deposit in the Syrdarya depression were identified using an X-ray diffraction analysis. It was established that ores of the Santonian stage are relatively homogeneous and consist mainly of quartz. During well operation, the precipitates formed are predominantly gypsum, which has little impact on the filtration properties of the ore. Ores of the Maastrichtian stage are less homogeneous and mainly composed of quartz and smectite, with minor amounts of potassium feldspar and kaolinite. The leaching of these ores results in the formation of gypsum with quartz impurities, which gradually reduces the filtration properties of the ore. Ores of the Campanian stage are heterogeneous, consisting mainly of quartz with varying proportions of clay minerals and gypsum. The leaching of these ores generates a variety of precipitates that significantly reduce the filtration properties of the productive horizon. Effective compositions and concentrations of decolmatant (clog removal) solutions were selected under laboratory conditions using a specially developed methodology and a TESCAN MIRA scanning electron microscope. Based on a scanning electron microscope analysis of the samples, the effectiveness of a decolmatizing solution based on hydrochloric and hydrofluoric acids (taking into account the concentration of the acids in the solution) was established for the destruction of precipitate formation during the in situ leaching of uranium. Geological blocks were ranked by their clay content to select rational parameters of decolmatant solutions for the efficient enhancement of ore filtration properties and the prevention of precipitation formation. Pilot-scale testing of the selected decolmatant parameters under various mining and geological conditions allowed the optimal chemical treatment parameters to be determined based on the clay content and the composition of precipitates in the productive horizon. An analysis of pilot well trials using the new approach showed an increase in the uninterrupted operational period of wells by 30%–40% under average mineral acid concentrations and by 25%–45% under maximum concentrations with surfactant additives in complex geological settings. As a result, an effective methodology for ranking geological blocks based on their ore clay content and precipitate composition was developed to determine the rational parameters of decolmatant solutions, enabling a maximized filtration performance and an extended well service life. This makes it possible to reduce the operating costs of extraction, control the geotechnological parameters of uranium well mining, and improve the efficiency of the in situ leaching of uranium under complex mining and geological conditions. Additionally, the approach increases the environmental and operational safety during uranium ore leaching intensification. Full article
(This article belongs to the Section Mineral Processing and Extractive Metallurgy)
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21 pages, 4014 KB  
Article
Optimized Mortar Formulations for 3D Printing: A Rheological Study of Cementitious Pastes Incorporating Potassium-Rich Biomass Fly Ash Wastes
by Raúl Vico Lujano, Luis Pérez Villarejo, Rui Miguel Novais, Pilar Hidalgo Torrano, João Batista Rodrigues Neto and João A. Labrincha
Materials 2025, 18(15), 3564; https://doi.org/10.3390/ma18153564 - 30 Jul 2025
Viewed by 826
Abstract
The use of 3D printing holds significant promise to transform the construction industry by enabling automation and customization, although key challenges remain—particularly the control of fresh-state rheology. This study presents a novel formulation that combines potassium-rich biomass fly ash (BFAK) with an air-entraining [...] Read more.
The use of 3D printing holds significant promise to transform the construction industry by enabling automation and customization, although key challenges remain—particularly the control of fresh-state rheology. This study presents a novel formulation that combines potassium-rich biomass fly ash (BFAK) with an air-entraining plasticizer (APA) to optimize the rheological behavior, hydration kinetics, and structural performance of mortars tailored for extrusion-based 3D printing. The results demonstrate that BFAK enhances the yield stress and thixotropy increases, contributing to improved structural stability after extrusion. In parallel, the APA adjusts the viscosity and facilitates material flow through the nozzle. Isothermal calorimetry reveals that BFAK modifies the hydration kinetics, increasing the intensity and delaying the occurrence of the main hydration peak due to the formation of secondary sulfate phases such as Aphthitalite [(K3Na(SO4)2)]. This behavior leads to an extended setting time, which can be modulated by APA to ensure a controlled processing window. Flowability tests show that BFAK reduces the spread diameter, improving cohesion without causing excessive dispersion. Calibration cylinder tests confirm that the formulation with 1.5% APA and 2% BFAK achieves the maximum printable height (35 cm), reflecting superior buildability and load-bearing capacity. These findings underscore the novelty of combining BFAK and APA as a strategy to overcome current rheological limitations in digital construction. The synergistic effect between both additives provides tailored fresh-state properties and structural reliability, advancing the development of a sustainable SMC and printable cementitious materials. Full article
(This article belongs to the Section Construction and Building Materials)
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Article
Wettability Characteristics of Mixed Sedimentary Shale Reservoirs in Saline Lacustrine Basins and Their Impacts on Shale Oil Energy Replenishment: Insights from Alternating Imbibition Experiments
by Lei Bai, Shenglai Yang, Dianshi Xiao, Hongyu Wang, Jian Wang, Jin Liu and Zhuo Li
Energies 2025, 18(14), 3887; https://doi.org/10.3390/en18143887 - 21 Jul 2025
Viewed by 735
Abstract
Due to the complex mineral composition, low clay content, and strong heterogeneity of the mixed sedimentary shale in the Xinjiang Salt Lake Basin, the wettability characteristics of the reservoir and their influencing factors are not yet clear, which restricts the evaluation of oil-bearing [...] Read more.
Due to the complex mineral composition, low clay content, and strong heterogeneity of the mixed sedimentary shale in the Xinjiang Salt Lake Basin, the wettability characteristics of the reservoir and their influencing factors are not yet clear, which restricts the evaluation of oil-bearing properties and the identification of sweet spots. This paper analyzed mixed sedimentary shale samples from the Lucaogou Formation of the Jimsar Sag and the Fengcheng Formation of the Mahu Sag. Methods such as petrographic thin sections, X-ray diffraction, organic matter content analysis, and argon ion polishing scanning electron microscopy were used to examine the lithological and mineralogical characteristics, geochemical characteristics, and pore space characteristics of the mixed sedimentary shale reservoir. Alternating imbibition and nuclear magnetic resonance were employed to quantitatively characterize the wettability of the reservoir and to discuss the effects of compositional factors, lamina types, and pore structure on wettability. Research findings indicate that the total porosity, measured by the alternate imbibition method, reached 72% of the core porosity volume, confirming the effectiveness of alternate imbibition in filling open pores. The Lucaogou Formation exhibits moderate to strong oil-wet wettability, with oil-wet pores predominating and well-developed storage spaces; the Fengcheng Formation has a wide range of wettability, with a higher proportion of mixed-wet pores, strong heterogeneity, and weaker oil-wet properties compared to the Lucaogou Formation. TOC content has a two-segment relationship with wettability, where oil-wet properties increase with TOC content at low TOC levels, while at high TOC levels, the influence of minerals such as carbonates dominates; carbonate content shows an “L” type response to wettability, enhancing oil-wet properties at low levels (<20%), but reducing it due to the continuous weakening effect of minerals when excessive. Lamina types in the Fengcheng Formation significantly affect wettability differentiation, with carbonate-shale laminae dominating oil pores, siliceous laminae contributing to water pores, and carbonate–feldspathic laminae forming mixed pores; the Lucaogou Formation lacks significant laminae, and wettability is controlled by the synergistic effects of minerals, organic matter, and pore structure. Increased porosity strengthens oil-wet properties, with micropores promoting oil adsorption through their high specific surface area, while macropores dominate in terms of storage capacity. Wettability is the result of the synergistic effects of multiple factors, including TOC, minerals, lamina types, and pore structure. Based on the characteristic that oil-wet pores account for up to 74% in shale reservoirs (mixed-wet 12%, water-wet 14%), a wettability-targeted regulation strategy is implemented during actual shale development. Surfactants are used to modify oil-wet pores, while the natural state of water-wet and mixed-wet pores is maintained to avoid interference and preserve spontaneous imbibition advantages. The soaking period is thus compressed from 30 days to 3–5 days, thereby enhancing matrix displacement efficiency. Full article
(This article belongs to the Special Issue Sustainable Development of Unconventional Geo-Energy)
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