Search Results (274)

Background/Objectives: Atypical femoral fracture (AFF) represents a diagnostic and therapeutic challenge, particularly in autoimmune disease patients receiving long-term bisphosphonate (BP) and glucocorticoid (GC) therapy. Although bilateral AFF is common, the radiographic evolution of asymptomatic incomplete lesions identified at the time of a complete fracture remains insufficiently defined. This study aimed to characterize the natural history and imaging biomarkers associated with progression in this biologically homogeneous high-risk population. Methods: Ten female autoimmune disease patients with complete AFF and asymptomatic incomplete contralateral lesions were retrospectively evaluated over a mean 59 months. Serial radiographs were assessed for cortical beaking, periosteal flaring, and transverse radiolucent lines. All patients discontinued BP therapy postoperatively; teriparatide was administered when tolerated. Results: Six lesions regressed, three remained stable, and one progressed—this progressing case being the only limb with a transverse radiolucent line at baseline. No patient developed symptoms or sustained a complete fracture on the contralateral side. Radiographic remodeling occurred independently of symptoms. BP discontinuation and, when tolerated, teriparatide appeared to contribute to lesion stabilization, although statistical significance was not achieved. Conclusions: In autoimmune patients with severe long-term BP and GC exposure, most asymptomatic incomplete AFF identified at the time of contralateral complete fracture remains stable or improves under conservative management. A transverse radiolucent line is the most decisive imaging biomarker predictive of progression and warrants intensified surveillance or consideration of prophylactic fixation. Larger cohorts are needed to refine risk stratification algorithms and optimize diagnostic and management strategies. Full article

The “bauxite gas reservoir” in the Ordos Basin represents a novel exploration domain, yet the mechanisms governing its widespread aluminous fracture fillings remain unclear. This study integrates core observation, thin-section analysis, geochemical simulation, and rock physics to investigate the formation and impact of these fracture systems. Results identify a characteristic filling evolutionary sequence of “wall-lining film → oolitic/globular → plug-like → vermicular.” Geochemical simulations confirm that increasing pH and decreasing Eh driven by water–rock interactions are the key drivers for aluminous mineral precipitation. A distinct well log response model characterized by high GR, DEN, and CNL values coupled with low AC and RT is established for effective identification. Seepage experiments reveal that while Al–Si colloidal fracture fillings reduce permeability, they act as natural proppants to preserve effective flow channels, acting as a crucial high-permeability network for gas migration despite the mineral occlusion. These findings refine the accumulation theory for bauxite series reservoirs and provide geological evidence for deep tight gas exploration. Full article

Accurately assessing collapse risks of high-elevation, concealed rock mass blocks within the steep cliffs of Bijiashan, Three Gorges Reservoir Area, is challenging. This study employed a multidimensional approach—integrating airborne Light Detection and Ranging (LiDAR), the transient electromagnetic method (TEM), close-range photogrammetry, horizontal drilling, and borehole optical imaging—to characterize the rock mass structure of the WD1 cliff belt and delineate 52 individual blocks. Stability analysis incorporated stereographic projection for macro-scale assessment and employed mechanical models specific to three primary failure modes (toppling, sliding, falling). Finite element strength reduction quantified the stress–strain response of a representative block under natural and rainstorm conditions. Particle Flow Code (PFC) simulated dynamic instability of the exceptionally large block W1-37. Results indicate the WD1 rock mass is highly fractured, with base sections prone to weakness. Toppling failure dominates (90.4%). Under rainstorm conditions, the average Factor of Safety (FOS) decreased by 14.7%, and 73.1% of the blocks that were stable under natural conditions were destabilized—specifically transitioning to marginally stable or substable states—often triggering chain-reaction instability characterized by “crack propagation—base buckling”. W1-37 exhibited staged failure under rainstorm: “strain localization at fissure tips—penetration of basal cracks—overturning of the upper rock mass”. Its frontal rock reached a peak sliding velocity of 15.17 m/s, indicative of base-breaking toppling. The integrated “multi-technology survey—multi-method evaluation—multi-scale simulation” framework provides a quantitative basis for risk assessment of rock mass disasters in the Three Gorges Reservoir Area and offers a technical paradigm for similar high-steep canyon regions. Full article

Complex landslides have characteristics and parameters that are difficult to analyze. The landslide on 16 June 2024 in the rural community of Quilloturo (Tungurahua, Ecuador) caused severe damage (14 deaths, 24 injuries, and hundreds of affected families) related to the area’s geological, social, and anthropogenic conditions. Its location in the eastern foothills of Ecuador’s Cordillera Real exacerbated the effects of a landslide involving various processes (mud and debris flows, landslides, and rock falls). This event was preceded by intense rainfall lasting more than 10 h, which accumulated and caused natural damming of the streams prior to the event. The lithology of the investigated area includes deformed metamorphic and intrusive rocks overlain by superficial clayey colluvial deposits. The relationship between the geological structures found, such as fractures, joints, schistosity, and shear, favored the formation of blocks within the flow, making mass movement more complex. Geomorphologically, the area features a relief with steep slopes, where ancient landslides or material movements, composed of these colluvial deposits, have already occurred. At the foot of these steep slopes, on plains less than 300 m wide and bordered by the Pastaza River, there are human settlements with less than 60 years of emplacement and a complex history of territorial occupation, characterized by a lack of planning and organization. The memory of the inhabitants identified mass movements that have occurred since the mid-20th century, with the highest frequency of occurrence recorded in the last decade of the present century (2018, 2022, and 2024). Furthermore, it was possible to identify several factors within the knowledge of the inhabitants that can be considered premonitory of a mass movement, specifically a flood, and that must be incorporated as critical elements in decision-making, both individual and collective, for the evacuation of the area. Full article

Background/Objectives: Benign bone tumors and tumor-like conditions are commonly encountered in the pediatric population, often discovered incidentally during radiographic evaluation or presenting with symptoms such as pain, swelling, or pathologic fractures. Despite their benign nature, these lesions can significantly impact bone integrity and function. The objective of this study was to characterize the epidemiology, histopathological spectrum and management of benign bone tumors in a pediatric population. Methods: We conducted a retrospective observational single-center study of pediatric patients diagnosed with benign bone tumors or tumor-like lesions between 2013 and 2023. Clinical presentations, radiological findings, histopathological diagnoses, and treatment modalities were reviewed. Biopsy results and surgical indications were analyzed to assess diagnostic yield and therapeutic strategies. Results: Among the 253 biopsies performed, 220 cases (86.6%) were diagnosed as benign tumors, with osteochondromas being the most common (62.3%). The majority of cases involved the appendicular skeleton, with a male predominance. Simple bone cysts, aneurysmal bone cysts, and nonossifying fibromas were also frequently observed. Pathological fractures were documented in 5.45% of cases. Surgical intervention was indicated in patients with symptomatic lesions, pathological fractures, or radiological signs of structural instability. Conclusions: Benign bone tumors and tumor-like lesions in pediatric patients, although non-malignant, may lead to significant skeletal complications. Our findings highlight the importance of structured diagnostic evaluation and individualized treatment planning based on lesion type, location and clinical presentation. Early radiological assessment combined with histopathological confirmation plays a key role in preventing complications and optimizing outcomes. A multidisciplinary approach remains essential in the comprehensive management of these conditions. Full article

Natural fractures in tight sandstone reservoirs are the key factors controlling hydrocarbon flow and productivity. The Bozi-1 gas reservoir in the Kuqa Depression, as a typical ultra-deep tight sandstone gas reservoir, is characterized by low-porosity and ultra-low-permeability sandstones. This study addresses the limitations of previous fracture characterization, which primarily focused on macro-structural fractures while neglecting medium- and small-scale fractures. We integrate multi-source heterogeneous data, including core, well-logging imaging, seismic, and production observations, to systematically conduct multi-scale natural fracture characterization and modeling. First, the overall geology of the study area is briefly introduced, followed by a detailed description of the development characteristics of large-scale and medium–small-scale fractures, achieving a multi-scale representation of complex curved fracture networks. Finally, the three-dimensional multi-scale fracture model is validated using static indicators, including production characteristics, water invasion features, and well leakage data. The main findings are as follows: (1) Large-scale fractures in the Bozi-1 reservoir are mainly oriented near EW, NE–SW, and NW–SE, acting as the primary hydrocarbon migration pathways. Medium–small-scale fractures predominantly develop near SN, NE–SW, NW–SE, and near EW directions, exhibiting strong heterogeneity. (2) The complex curvature of large-scale fractures was captured by the “adaptive sampling + segmented splicing + equivalent distribution of fracture flow capacity” method, while the distribution of effective medium–small-scale fractures across the study area was represented using “single-well Stoneley wave inversion + seismic machine learning prediction”, achieving an 86% match with actual single-well measurements. (3) Model reliability was further verified through static comparisons, including production characteristics (unimpeded flow vs. effective fracture density, R² = 0.92), water invasion features (fracture-dominated water invasion matching fracture distribution), and well leakage characteristics (matching rate of high fracture density zones: 84.2%). The results provide key technical support for the precise characterization of fracture systems and establish a model ready for dynamic simulation in ultra-deep tight sandstone gas reservoirs. Full article

Deep shale reservoirs in the Luzhou Block are characterized by developed fractures and complex structure. Accurate identification and characterization of natural fractures in reservoirs are crucial for shale gas exploration and development. In this paper, the main development characteristics of natural fractures in the target layer were clarified based on core observation data and imaging logging data, and then the natural fractures were identified by combining the R/S analysis method. Furthermore, due to the different orientations of different fractures, there are differences in fracture activation pressure and drilling fluid leakage, which have a significant impact on the identification of risk zones. The results showed that low-angle and east–west oriented fractures are not easily activated because their orientation relative to the maximum horizontal principal stress is unfavorable, resulting in lower shear stress on the fracture planes. Moreover, after fracture activation, the opening deformation decreases with increasing inclination, leading to differential changes in the leakage rate. The 60° inclination angle fracture is the critical value for high-risk leakage compared to the low-risk leakage. The research results can provide important guidance for further drilling optimization and development of deep shale gas in the Luzhou Block. Full article

The development of deep coalbed methane is hindered by the strong heterogeneity of coal mechanical properties and complex hydraulic fracturing behavior. To identify the key factors controlling fracture geometry and permeability enhancement, this study developed a thermo-hydro-mechanical-damage coupled model within a COMSOL Multiphysics 6.3-MATLAB R2022b co-simulation framework, incorporating a Weibull random field to characterize mechanical heterogeneity. Sensitivity analysis demonstrates that tensile strength is the predominant factor governing both the fracturing damage zone and permeability-enhanced area, with its damage area extreme difference (10.094) and coefficient of variation (0.85) significantly surpassing those of other parameters. Poisson’s ratio and elastic modulus emerge as key secondary parameters, while compressive strength shows the lowest sensitivity. The parametric influences exhibit distinct patterns: tensile strength shows a strong negative correlation with damage and permeability-enhanced areas (up to 85% reduction), whereas the maximum permeability enhancement rate follows a non-monotonic trend, peaking at 215 when tensile strength reaches 3.33 MPa. Compressive strength minimally affects the damage area (~15%) but steadily improves the maximum permeability enhancement rate (7.5% increase). Elastic modulus exhibits an optimal value (8.93 GPa) for maximizing damage area, while negatively correlating with maximum permeability enhancement rate (9.1% decrease). Fracture morphology is differentially controlled by multiple parameters: low compressive strength promotes fracture deflection and branching, elastic modulus regulates fracture network complexity, and low Poisson’s ratio enhances coal brittleness to effectively activate natural fractures, thereby facilitating complex fracture network formation. Full article

To tackle the critical challenges of silica dispersion and interfacial compatibility in natural rubber composites, this study investigated the dispersion behavior of 3-Octanoylthio-1-propyltriethoxysilane (NXT)-modified silica in natural rubber (NR) and the mechanism by which it affects mechanical properties. Three distinct models were constructed: an NR model, an NR composite model containing unmodified silica (SiO₂), and an NR composite model containing NXT-modified silica (NXT-SiO₂). The radial distribution function (RDF) was used to characterize the dispersion of fillers. The results of filler–filler interactions revealed a reduction in the number of hydrogen bonds between NXT-SiO₂ fillers, weakening the filler network strength and enabling NXT-SiO₂ to exhibit excellent dispersion. The results of filler–rubber interactions indicated that NXT-SiO₂ exhibited stronger interaction forces and compatibility with natural rubber compared to SiO₂. To verify the effect of NXT-SiO₂ on the mechanical properties of natural rubber composites, uniaxial tensile deformation via molecular dynamics simulation was performed on the three models. The simulation results show that the addition of NXT-SiO₂ significantly increases the tensile strength and fracture strain of the composite material, markedly enhancing its mechanical properties. Further studies indicate that NXT-SiO₂ improves the overall mechanical properties of the material by altering the distribution of local natural rubber chains. This work elucidated the intrinsic mechanisms—on a molecular level—by which NXT silane coupling agent modifications enhance the dispersion of fillers and improve the mechanical properties of rubber, thereby providing a theoretical basis for the design of high-performance rubber composites. Full article

Microwave fracturing and assisted mechanical breakage offer efficient and cost-effective rock excavation potential. However, these methods have not been well studied or understood for the deployment of in situ recovery (ISR) in mining, which could benefit from microwave-induced cracking to accelerate in situ leaching. This paper reports on investigations into the effects of microwaves on rock transport properties, specifically for in situ recovery applications. The research focused on microwave fragmentation of a synthetic ore with composition and particle size similar to many wet ore-bearing deposits, as well as hard lithium-bearing rock (spodumene) as a natural analogue, to assess changes in porosity and permeability after microwave treatment. The experiments involved exposing samples with varying water content to heating with different microwave energy levels, followed by examining the impact on the induced crack characteristics. All the samples were characterized by a suite of measurements before and after microwave treatment, including scanning electron microscopy (SEM), Nuclear Magnetic Resonance (NMR), nitrogen gas permeameter-porosimeter, and P-wave velocity measurements. The results showed a strong dependence of rock properties after microwave treatment on water content. At high water content (100%), NMR results showed a substantial increase in porosity, by nearly 17% and a dramatic 47-fold rise in permeability, from 0.65 mD to 311 mD. However, the treatment also caused partial melting of the sample, rendering it unsuitable for further testing, including permeability and P-wave velocity. At moderate water content (20%), permeability substantially increased (233–3404%), which was consistent with the observation of multiple cracks in SEM images. These changes led to low P-wave velocity values. This research provides crucial insights into microwave fracturing as a method for in situ recovery in mining. Full article

Urban fragmentation has emerged as a central issue in the study of socio-spatial dynamics in contemporary cities, reflecting processes of inequality, segregation, and spatial discontinuities. This article introduces a new methodological approach to measure fragmentation by focusing on discontinuities at limits rather than on the content of statistical units alone. The method applies robust standardization of selected socioeconomic variables—higher education, foreign-born population, and low-income population—at the census tract scale in the city of Lleida, Spain. Rupture intensity is measured through a Rupture Intensity Index, which integrates standardized differences across 217 limits. Principal component analysis identifies the most influential variables, while cluster analysis characterizes the multidimensional nature of limits. Results show that fragmentation in Lleida does not follow a simple center–periphery model but a tessellated pattern of fracture lines and gradient zones. Intense fractures emerge at borders between advantaged and disadvantaged neighborhoods, whereas gradients mark gradual transitions. The study demonstrates that limits are critical sites for observing and quantifying urban fragmentation and proposes a transferable methodology for comparative research and urban policy design in diverse urban contexts. This approach provides a replicable tool for urban analysis and the design of cohesion-oriented policies. Full article

The Middle Jurassic Lianggaoshan and Shaximiao Formations are the primary crude oil reservoirs in the central Sichuan Basin, offering significant resource potential. However, studies on reservoir characterization across different lithologies remain limited. This study focuses on fluvial–deltaic sandstones, siltstones, and lacustrine shales, analyzing pore types, structures, pore size distribution, and connectivity using various methods, including X-ray diffraction (XRD), thin-section analysis, scanning electron microscopy (SEM), high-pressure mercury injection, low-temperature nitrogen adsorption, and nuclear magnetic resonance (NMR) spectroscopy. The results show that sandstones exhibit the largest pore space, followed by siltstones, while shales have the smallest pore space. These reservoirs are relatively tight, with poor connectivity and high heterogeneity. Sandstone reservoirs, with their high quartz content, represent high-quality reservoirs because of their relatively good connectivity. Therefore, areas with well-developed natural fractures in sandstone are considered high-quality targets. For nanoscale reservoirs in siltstone and shale, horizontal fracturing is essential to improve reservoir properties, provided that source–reservoir matching is adequate. This study offers a detailed reservoir characterization across different lithologies, providing new insights for the optimization of favorable crude oil zones in the central Sichuan Basin. Full article

Single-use plastic cups and packaging materials pose severe environmental challenges due to their persistent nature and harmful impact on ecosystems and wildlife. Simultaneously, the indiscriminate disposal and burning of agricultural and food processing biomass contribute significantly to pollution. Among this biomass, waste generated from corn and fruit processing is produced in substantial quantities and is rich in natural fibres, making it a potential source for developing biodegradable products. This study focuses on the development of biodegradable cups using corn cob powder, mango peel powder, and pineapple peel powder through hot-press compression and moulding technology. The formulation was optimized using response surface methodology, with independent variables, i.e., corn cob (20–40 g), mango peel (30–50 g), and pineapple peel (20–30 g). The responses evaluated including hardness, colour (L* value), and water-holding capacity. The model was fitted using a second-order polynomial equation. Optimum results were achieved with 34 g of corn cob, 40 g of mango peel, and 26 g of pineapple peel powder, yielding a maximum hardness of 2.41 kg, an L* value of 47.03, and a water-holding capacity of 18.25 min. The optimized samples further underwent characterization of physical properties, functional groups, lattice structure, surface morphology, and biodegradability. Colour parameters were recorded as L* = 47.03 ± 0.021, a* = 10.47 ± 0.041, and b* = 24.77 ± 0.032. Textural study revealed a hardness of 2.411 ± 0.063 and a fracturability of 2.635 ± 0.033. The developed biodegradable cup had a semicrystalline nature with a crystallinity index of 44.4%. Soil burial tests confirmed that the developed cups degraded completely within 30 days. These findings highlight the potential of corn and fruit processing waste for developing eco-friendly, biodegradable cups as sustainable alternatives to single-use plastics. Full article

The increasing demand for sustainable construction materials has prompted the recycling of construction and demolition waste in concrete manufacturing. This study investigates the feasibility of utilizing porcelain and brick waste as partial substitutes for natural sand in concrete with the objective of improving sustainability and preserving mechanical and durability characteristics. The experimental program was conducted in three consecutive phases. During the initial phase, natural sand was partially substituted with porcelain waste powder (PWP) and brick waste powder (BWP) in proportions of 25%, 50%, and 75% of the weight of the fine aggregate. During the second phase, polypropylene fibers were mixed at a dosage of 0.5% by volume fraction to enhance tensile and flexural properties. During the third phase, zinc oxide nanoparticles (ZnO-NPs) were utilized as a partial substitute for cement at concentrations of 0.5% and 1% to improve microstructure and strength progression. Concrete samples were tested at curing durations of 7, 28, and 91 days. The assessed qualities encompassed workability, density, water absorption, porosity, compressive strength, flexural strength, and splitting tensile strength. Microstructural characterization was conducted utilizing X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDS). The findings indicated that porcelain waste powder markedly surpassed brick waste powder in all mechanical and durability-related characteristics, particularly at 25% and 50% sand replacement ratios. The integration of polypropylene fibers enhanced fracture resistance and ductility. Moreover, the incorporation of zinc oxide nanoparticles improved hydration, optimized the pore structure, and resulted in significant enhancements in compressive and tensile strength throughout prolonged curing durations. The best results were obtained with a mix of 50% porcelain sand aggregate, 1% zinc oxide nanoparticles as cement replacement, and 0.5% polypropylene fibers, for which the improvements in compressive strength, flexural strength, and splitting tensile strength were 39.5%, 46.2%, and 60%, respectively, at 28 days. The results confirm the feasibility of using porcelain and brick waste as sand replacements in concrete, as well as polypropylene fiber-reinforced concrete and polypropylene fiber-reinforced concrete mixed with zinc oxide nanoparticles as a sustainable option for construction purposes. Full article

During natural gas extraction, understanding multiphase flow in fractured reservoirs remains a critical challenge due to the heterogeneous distribution of pores and fractures and the multi-scale nature of seepage mechanisms. These complexities introduce randomness in fluid distribution and tortuosity in seepage channels, limiting accurate characterization of gas-water flow. To address this issue, a dual-medium gas-water two-phase relative permeability model is developed by incorporating the fractal dimension of fracture surfaces, the tortuosity of the rock matrix, and the stress sensitivity of fracture networks. The model integrates essential microstructural parameters to capture the nonlinear flow behavior in dual-porosity systems. A systematic sensitivity analysis is conducted to evaluate the effects of fracture and matrix properties on the relative permeability curve. Results indicate that the fracture surface fractal dimension exerts a dominant influence in the two-phase flow region (fracture fractal dimensions in the range of 1.6–2.8), while near single-phase flow, fracture fractal dimensions in the range of 2.4–2.8 strongly affect flow behavior. Overall, the findings demonstrate that fracture-related parameters play a greater role than matrix properties in governing permeability evolution. This study provides predictive capability for two-phase flow in stress-sensitive fractured carbonates. Full article