Search Results (469)

To support intelligent and sustainable mine engineering, this geotechnics-based study integrates laboratory testing, three-dimensional numerical simulation, and field monitoring to optimize roadway support and improve resource efficiency. This study investigates the geotechnical behavior of the surrounding rock in coalmine roadways under single-face unloading conditions, aiming to provide theoretical and practical support for surrounding rock control in underground coal mining. Excavation of the roadway creates a free surface, leading to unloading, which makes timely support crucial for preventing instability. True-triaxial single-face unloading tests and mechanical tests on hole-containing coal specimens show that the coal exhibits four characteristic stages, namely fissure compaction (closure), elastic deformation, yielding, and residual strength. Under a confining stress of 4 MPa, the peak strength of Coal Seam No. 3 in the true-triaxial single-face unloading test reached 32.4 MPa, whereas the peak strength of the hole-containing coal specimen was only 17.1 MPa, and failure occurred as instantaneous global instability with an “X”-shaped conjugate shear pattern. Numerical simulations were conducted to optimize the roadway’s surrounding rock control scheme, indicating that increasing the bolt length increases the proportion of the load carried by the rock bolts while reducing the load borne by the cable bolts. In addition, advance abutment pressure increases the forces in the support system and amplifies deformation of the solid rib, coal-pillar rib, and roof; roadway surface convergence is dominated by floor heave. Full article

Shale oil reservoirs are complex multi-scale nanoporous media where fluid transport is governed by coupled micro-mechanisms, demanding a robust modeling framework. This study presents a novel fluid–solid coupling (FSC) numerical model that rigorously integrates the three primary scale-dependent transport phenomena: adsorption in organic nanopores, slip effects in inorganic micropores, and stress-sensitive conductivity in fractures. The model provides essential quantitative insights into the dynamic interaction between fluid withdrawal and reservoir deformation. Simulation results reveal that microstructural properties dictate the reservoir’s mechanical stability. Specifically, larger pore diameters and higher porosity enhance stress dissipation, promoting long-term stress relaxation and mitigating permeability decay. Crucially, tortuosity governs the mechanical response by controlling pressure transmission pathways: low tortuosity causes localized stress concentration, leading to rapid micro-channel closure, while high tortuosity ensures stress homogenization, preserving long-term permeability. Furthermore, high fracture conductivity induces a severe, heterogeneous stress field near the wellbore, which dictates early-stage mechanical failure. This work provides a powerful, mechanism-based tool for optimizing micro-structure and production strategies in unconventional resources. Full article

Within the Rajidae family, the blonde ray (Raja brachyura) is considered one of the less resilient species to fishing pressure and other anthropogenic pressures, primarily due to its late maturity and large maximum size, which can exceed 120 cm total length. This is the first study to provide comprehensive insights into the reproductive biology of Raja brachyura in the continental waters of Portugal, with insights into its timing, maturity, and fecundity. It was determined that egg-laying occurs from February to November, with a peak observed between April and September. Males were reproductively active throughout the year, with highest proportions of active males observed between January and May. The length at first maturity was estimated at 95.2 cm for females and 90.0 cm for males, corresponding to 85% of the maximum observed length in each sex. The potential fecundity was estimated at 115 follicles per female per year, and evidence suggests that the species has a determinate fecundity. The findings reinforce the appropriateness of current management measures in Portuguese continental waters, namely seasonal closure when overlapping with the peak of the reproductive season (May and June), and provide valuable scientific support for future conservation and management measures. Full article

Hard-to-heal wounds remain a significant challenge for healthcare professionals, particularly in aging populations. Although most chronic wounds are associated with diabetes or chronic venous insufficiency, rare etiologies should also be considered. One such cause is envenomation by Phoneutria spp. (native to South America, rare in Europe). Their venom contains potent neurotoxins. While systemic manifestations are more commonly reported, localized necrotic skin lesions may also occur. This case report presents a rare chronic wound following a suspected Phoneutria spider bite and highlights the importance of an individualized, multimodal treatment approach. A 61-year-old male patient with a progressive thigh wound following a spider bite sustained during work. Despite initial self-treatment and pharmacotherapy the wound deteriorated. The patient was admitted to the authors’ facility, where surgical treatment included necrosectomy and a sandwich graft using an acellular dermal matrix combined with a split-thickness skin graft. Adjunctive therapies included negative pressure wound therapy and hyperbaric oxygen therapy. After discharge, outpatient wound care was continued. Treatment was monitored with photographic documentation and serial microperfusion measurements. Complete wound closure was achieved after 4 months of specialized therapy. Management of chronic wounds requires a multidisciplinary and individualized approach with surgical intervention, advanced wound care and specialized outpatient follow-up. Full article

This article provides an in-depth overview of mine gas emission monitoring practices in the Ostrava-Karviná Coalfield (OKR), one of the most significant regions in Central Europe affected by post-mining methane leakage. The study presents field measurement techniques, including atmogeochemical surveys, systematic methane screening in soil air, and surface emission rate monitoring using accumulation chambers. Over the course of several long-term projects, more than 43 km² of land were surveyed, and risk classification maps were developed based on measured methane concentrations and surface release rates. These data support land-use planning, the design of degasification measures, and the verification of their effectiveness. Results confirm that methane emissions persist even decades after mine closures and vary depending on atmospheric pressure and local geological conditions. The OKR methodology was also compared to international practices in Poland, Canada, and China. The article concludes with future research directions focused on automation, integration of sensor networks, and predictive modeling of gas migration in post-mining environments. Full article

Background and Clinical Significance: Tramadol-associated acute angle-closure crisis is rare and has been reported only once previously following subcutaneous administration. Acute angle closure may occur in anatomically predisposed individuals in the setting of perioperative physiological stress, with medications acting as contributory factors. Case Presentation: A 38-year-old woman developed a bilateral acute angle-closure crisis shortly after initiating oral tramadol for postoperative pain relief following an uncomplicated robotic-assisted laparoscopic hysterectomy. Within 24 h, she experienced headache, nausea, vomiting, periocular pain, and blurred vision. Ophthalmic examination revealed markedly elevated intraocular pressure (45 mmHg OD, 39 mmHg OS), corneal epithelial edema, mid-dilated pupils, and completely closed angles on gonioscopy. Prompt intraocular pressure–lowering therapy followed by bilateral Nd:YAG laser peripheral iridotomy resulted in full anatomical and functional recovery, with visual acuity returning to baseline within 48 h. Conclusions: In this case, extreme anatomical susceptibility due to significant hyperopia and very short axial lengths likely played a dominant role, with perioperative physiological factors contributing to pupillary dilation. Oral tramadol may have acted as a permissive factor lowering the threshold for angle closure rather than as a sole causative agent. Awareness of this potential association is important to facilitate early ophthalmic referral and prevent unnecessary diagnostic evaluations. Full article

Background: Descemet membrane endothelial keratoplasty (DMEK) is the most frequently performed keratoplasty procedure in many countries. One of the most common early complications is an elevation of intraocular pressure (IOP). The aim of this study was to characterize early postoperative IOP behavior following DMEK performed with 10% sulfur hexafluoride (SF₆) tamponade and to determine the frequency and timing of required IOP-lowering interventions within the first 48 h. Methods: We retrospectively reviewed postoperative outcomes of 116 consecutive DMEK procedures between May and December 2024 at the University Medical Center in Mainz, Germany. No specific exclusion criteria were applied. All surgeries included a surgical iridectomy at the 6 o’clock position, 10% (SF₆) tamponade, and maintaining a mid-normal IOP at the end of surgery. Postoperative assessments included IOP measured using Goldmann applanation tonometry, the percentage of gas fill in the anterior chamber evaluated at the slit lamp, and the need for IOP-lowering interventions as determined by the on-call resident at 3, 24, and 48 h after surgery. IOP-lowering interventions consisted of venting in cases of elevated IOP, gas fill > 90%, and/or suspected angle closure or pupillary block, as well as intravenous or oral acetazolamide in cases of moderate IOP elevation with a lower gas fill and a patent iridectomy. If a single intervention was insufficient, a combined approach was used. Results: A total of 116 eyes from 98 patients (62 female, mean age 73.0 ± 9.8 years) were analyzed. DMEK was combined with cataract surgery in 41 eyes, and 4 eyes underwent phakic DMEK. Postoperatively, all iridectomies remained patent, and no cases of pupillary block occurred. Mean IOP and gas fill were within normal limits and declined steadily during the first 48 h. IOP-lowering procedures were performed in 11 eyes (9.5%), including venting (n = 3), acetazolamide administration (n = 7), and a combination of both (n = 1). There was no difference between DMEK and triple-DMEK regarding postoperative gas fill, IOP, or the need for IOP-lowering interventions. Mean postoperative IOP was significantly higher, and IOP-lowering interventions were more frequent in glaucoma vs. non-glaucoma patients. Re-bubbling was performed in 12 eyes (10.3%). Two cases of primary graft failure (1.7%) were recorded. Conclusions: In our patient cohort, a standardized surgical approach incorporating a surgical iridectomy at the 6 o’clock position, 10% SF₆ tamponade, and maintaining a mid-normal IOP at the end of surgery effectively prevented pupillary block. We recommend early postoperative assessment of IOP and percent gas fill to promptly identify and manage impending IOP elevation, which is particularly important in patients with glaucoma. Full article

Coalbed methane development is constrained by reservoir characteristics including high gas adsorption, high salinity, and high closure pressure, which impose significant limitations on conventional polymer fracturing fluids regarding viscosity enhancement, proppant transport, and fracture maintenance. In this study, a novel polymer fracturing fluid system, Z-H-PAM, was designed and synthesized to achieve strong salt tolerance, low adsorption affinity, and high elasticity to withstand closure pressure. This was accomplished through the molecular integration of a zwitterionic monomer ZM-1 and a hydrophobic associative monomer HM-2, forming a unified structure that combines rigid hydrated segments with a hydrophobic elastic network. The results indicate that ZM-1 provides a stable hydration layer and low adsorption tendency under high-salinity conditions, while HM-2 contributes to a high-storage-modulus, three-dimensional physically cross-linked network via reversible hydrophobic association. Their synergistic interaction enables Z-H-PAM to retain viscoelasticity that is significantly superior to conventional HPAM and to achieve rapid structural recovery in high-mineralization environments. Systematic evaluation shows that this system achieves a static sand-suspension rate exceeding 95% in simulated flowback fluid, produces broken gel residues below 90 mg/L, and results in a core damage rate of only 10.5%. Moreover, it maintains 88.8% of its fracture conductivity under 30 MPa closure pressure. Notably, Z-H-PAM can be prepared directly using high-salinity flowback water, maintaining high elasticity and sand-carrying capacity while enabling fluid recycling and reducing reservoir damage. This work clarifies the multi-scale mechanisms of strongly hydrated and highly elastic polymers in coalbed methane reservoirs, offering a theoretical and technical pathway for developing efficient and low-damage fracturing materials. Full article

The transition to battery electric vehicles (BEVs) is enabling the significant redesign of key subsystems, including braking systems. This work presents a physics-based optimization framework for the preliminary design of a distributed electro-hydraulic brake-by-wire (DEHB) system tailored for electric vehicles. The DEHB system is modeled as a two-phase actuation process captured through a coupled electro-mechanical and hydraulic model: initial pad–disc clearance closure and subsequent pressure buildup. Sensitivity analysis is employed to identify critical design parameters, and a multi-objective genetic algorithm is used to minimize electrical power consumption, peak current, and maximum torque while satisfying performance constraints. The optimized configuration is benchmarked against commercially available solutions and validated against a multiphysics simulation, showing deviations below 8% for current and power. A dynamic analysis incorporating vehicle-level ABS logic demonstrates the improved performance and energy efficiency of the DEHB system during emergency braking, with a reduction of 50% in required power if compared to a non-optimized system. The results confirm the effectiveness of the proposed method for early-stage sizing and highlight the potential of DEHB architectures in future electric vehicle platforms. Full article

Background/Objectives: To evaluate risk factors for postoperative neurological deficits following cervical endoscopic unilateral laminotomy for bilateral decompression (CE-ULBD) and to determine whether intraoperative neurophysiological monitoring (IONM) can predict neurological compromise. Methods: A multicenter retrospective review was performed on 42 CE-ULBD procedures conducted between 2016 and 2024; 33 cases met the inclusion criteria with available imaging and electromyography data. Demographic, operative, and neurophysiological variables were analyzed. Preoperative stenosis severity was graded using the Kang MRI system. Intraoperative IONM data, including electromyography firing and motor evoked potential (MEP) changes, were correlated with new postoperative weakness. Results: The cohort (69.1% male, mean age 70.2 ± 1.7 years, mean BMI 29.6 ± 1.1) included 56 decompressed levels. The most common operative levels were C3-4 (37%) and C4-5 (24%). Postoperative weakness occurred in four patients (12.1%), all of whom had severe (Grade 3) preoperative stenosis. Among these, 50% exhibited preoperative weakness. Neuromonitoring changes correlated significantly with postoperative weakness (Fisher’s Exact, p < 0.001); 100% of patients with new post-operative weakness had sustained MEP decrease at the time of closure. Conclusions: Patients with severe cervical stenosis and preoperative weakness are at heightened risk of postoperative neurological deficits following CE-ULBD. Elevated epidural pressure from continuous irrigation in a constricted canal may exacerbate cord compression, particularly in those with preexisting myelopathy. IONM changes strongly correlate with new deficits and may exacerbate cord compression, particularly in those with preexisting myelopathy, and may serve as an early warning system for impending neurological injury. Surgeons should exercise caution and maintain low irrigation pressures in patients with severe stenosis undergoing endoscopic cervical decompression. Full article

Background: Posteriorly directed aneurysms at the internal carotid–posterior communicating artery (ICA–PCoA) junction concentrate technical risk at the posteromedial neck where the PCoA origin and perforators exist beneath the optic apparatus. Our aim was to describe, in a reproducible fashion, an anatomy-driven sequence in the management of a ruptured ICA–PCoA aneurysm that visualized the posterior wall and a closing line parallel to the PCoA axis and which is placed within contemporary practice. Case Presentation: This is a single case study employing predetermined surgical techniques demonstrating a reproducible method of anatomical microsurgery applied to a posterior projecting ICA-PCoA aneurysm. The authors describe a 62-year-old female who was stabilized by nimodipine and aggressive blood pressure control in the systolic range 140–160 mmHg after an aneurysmal subarachnoid hemorrhage. Diagnostic contrast catheter angiography showed a left ICA-PCoA aneurysm of 13.1 × 10.0 mm at the base with a neck of 4.3 mm projecting posteriorly into the carotid–optic cistern. Complete adherence to a protocol of staged techniques was employed for the operation, as detailed below. Step 1: Early cisternal decompression requiring total and immediate relaxation of the temporal lobe, rapidly opening up the carotid–optic anatomical window. Step 2: Circumferential dissection about the neck of the aneurysm permitting definition of the true posteromedial wall and definition of the perforator territories and anterior choroidal territories. Step 3: Brief but effective ICA proximal quiescence (58 s) permitting clipping under direct vision. Step 4: Staged closure of two clips with the closing line of the clips orientated parallel to the axis of the PCoA with maintenance of the diameter of all parent vessels, the origin of the PCoA and the integrity of the perforators. Urgent postoperative digital subtraction angiography (DSA) study showed complete exclusion of the aneurysm with no alteration in flow characteristics, and 3 months later DSA studies again showed permanent obliteration and patency of those branches. The immediate DSA demonstrated complete exclusion of the aneurysm with patent supraclinoid ICA caliber and PCoA ostium, the anterior choroidal artery was preserved; no angiographic vasospasm was identified. The postoperative course was uncomplicated; there was no hydrocephalus, seizure disorder or delayed ischemia. At discharge and three months postprocedure the patient was neurologically intact (Modified Rankin Scale 0). Non-contrast cranial CT (three months) demonstrated stable clip position and no hemorrhagic or ischemic sequelae. Conclusions: In posteriorly projecting ICA–PCoA aneurysms that are disturbed beneath the optic apparatus, an anatomy-guided strategy—early cisternal decompression, true posteromedial neck exposure, brief purposeful quieting of the proximal ICA and two-clip closure parallel to the PCoA in selected cases—may provide the opportunity for durable occlusion whilst the physiology of branching is preserved. We intend for this transparent description to be adopted, refined or discarded based on local anatomy and practice. Full article

The left atrial appendage (LAA) is a highly dynamic anatomical structure that plays a key role in left atrial reservoir function, pressure and volume modulation, and endocrine hormone secretion during sinus rhythm. However, its physiological contribution is profoundly altered in atrial fibrillation (AF). Electrical and structural remodeling, impaired contractility, and blood stasis within the LAA collectively transform this functional component into the principal cardiac source of thrombus formation and embolic events in patients with AF. This review focuses on the conceptual continuum from physiological LAA function in sinus rhythm to its pathological transformation in AF and the evolving rationale for progressively more complete (“radical”) anatomical exclusion A variety of strategies, including systemic anticoagulation therapy, percutaneous device-based exclusion, and surgical closure, are currently employed, each with specific indications, limitations, and procedure-related risks. Beyond summarizing available techniques, this review critically synthesizes mechanistic, anatomical, and clinical data to address unresolved controversies regarding patient selection, residual leaks, device-related thrombosis, and post-procedural antithrombotic management. Finally, emerging directions toward minimizing residual foreign material, reducing thrombogenicity, and achieving durable exclusion are discussed, supporting a more personalized and radical approach to stroke prevention in AF. Full article

The carbonate reservoir of the Shunbei oilfield is characterized by deep burial depth and high temperature. During acid fracturing, the reaction rate between conventional acid systems and the rock is relatively fast, leading to a limited effective acid penetration distance. To extend the acid penetration distance, a combination of solid retarded acid and conventional acid was used in field operations. The effectiveness of the solid retarded acid depends on its acid generation pattern, making it necessary to study the acid generation behavior of the solid retarded acid. This paper establishes a frame for evaluating the solid retarded acid, including tests for solid retarded acid solubility, acid concentration, and acid-etched fracture conductivity. Based on the test results, the acid generation pattern of solid retarded acid was analyzed, its slow-generation performance was evaluated, and an acid generation model was established. Finally, by integrating the acid generation model with the existing acid fracturing model, the effective distance of solid retarded acid was predicted. The study shows that the solubility of acid-generating materials is influenced by both temperature and solid retarded acid concentration. When the concentration of solid retarded acid exceeds 25%, it does not completely dissolve at room temperature, but can fully dissolve after 40 min at 120 °C. The acid concentration is significantly affected by temperature, with an acid concentration of about 1.6 mol/L at room temperature and up to 3.1 mol/L at high temperatures, comparable to a 12% hydrochloric acid concentration. Solid retarded acid exhibits good slow-generation performance, with a comprehensive reaction rate approximately one-third of that of cross-linked acid. When the acid-rock contact time is around 3 h, the acid-etched fracture conductivity of solid retarded acid can remain above 5 D·cm under a closure pressure of 60 MPa. The predicted effective acid penetration distance of solid retarded acid can reach over 150 m, under typical conditions of Shunbei oilfield. The findings of this study can serve as a reference for the design and optimization of solid retarded acid fracturing. Full article

Maintaining the stability of the mine roadway is of paramount importance, as it is critical in ensuring the daily operational continuity, personnel safety, long-term economic viability, and sustainability of the entire mining operation. Significant instability can trigger serious disruptions—such as production stoppages, equipment damage, and severe safety incidents—which ultimately compromise the project’s financial returns and future prospects. Therefore, the proactive assessment and rigorous control of roadway stability constitute a foundational element of successful and sustainable resource extraction. In China, thick and extra-thick coal seams constitute over 44% of the total recoverable coal reserves. Consequently, their safe and efficient extraction is considered vital in guaranteeing energy security and enhancing the efficiency of resource utilization. The surrounding rock of gob-side roadways in typical coal seams is often fractured due to high ground stress, intensive mining disturbances, and overhanging goaf roofs. Consequently, asymmetric failure patterns such as bolt failure, steel belt tearing, anchor cable fracture, and shoulder corner convergence are common in these entries, which pose a serious threat to mine safety and sustainable mining operations. This deformation and failure process is associated with several parameters, including the coal seam thickness, mining technology, and surrounding rock properties, and can lead to engineering hazards such as roof subsidence, rib spalling, and floor heave. This study proposes countermeasures against asymmetric deformation affecting gob-side entries under intensive mining pressure during the fully mechanized caving of extra-thick coal seams. This research selects the 8110 working face of a representative coal mine as the case study. Through integrated field investigation and engineering analysis, the principal factors governing entry stability are identified, and effective control strategies are subsequently proposed. An elastic foundation beam model is developed, and the corresponding deflection differential equation is formulated. The deflection and stress distributions of the immediate roof beam are thereby determined. A systematic analysis of the asymmetric deformation mechanism and its principal influencing factors is conducted using the control variable method. A support approach employing a mechanical constant-resistance single prop (MCRSP) has been developed and validated through practical application. The findings demonstrate that the frequently observed asymmetric deformation in gob-side entries is primarily induced by the combined effect of the working face’s front abutment pressure and the lateral pressure originating from the neighboring goaf area. It is found that parameters including the immediate roof thickness, roadway span, and its peak stress have a significant influence on entry convergence. Under both primary and secondary mining conditions, the maximum subsidence shows an inverse relationship with the immediate roof thickness, while exhibiting a positive correlation with both the roadway span and the peak stress. Based on the theoretical analysis, an advanced support scheme, which centers on the application of an MCRSP, is designed. Field monitoring data confirm that the peak roof subsidence and two-side closure are successfully limited to 663 mm and 428 mm, respectively. This support method leads to a notable reduction in roof separation and surrounding rock deformation, thereby establishing a theoretical and technical foundation for the green and safe mining of deep extra-thick coal seams. Full article

Net-cage aquaculture faces challenges from biofouling, which reduces water exchange and threatens structural integrity. Automated cleaning robots provide an alternative to human divers but require effective, low-cost localization. Conventional acoustic–inertial systems are expensive and complex, while vision-only or IMU-based methods suffer from drift in turbid, low-texture waters. This paper presents a lightweight Visual–Inertial–Depth (VID) fusion framework for underwater net-cage cleaning robots. Built on the VINS-Fusion system the method estimates scene scale using optical flow and stereo matching, and incorporates IMU pre-integration for high-frequency motion prediction. A pressure-based depth factor constrains Z-axis drift, and reflective-anchor initialization ensures global alignment. The system runs in real time on a Jetson Orin NX with ROS. Experiments in air, tank, pool, and ocean settings demonstrate its robustness. In controlled environments, the mean anchor coordinate error (ACE) was 0.05–0.16 m, and loop-closure drift (LCD) was ≤0.5 m per 5 m. In ocean trials, turbulence and biofouling led to drift (LCD 1.32 m over 16.05 m, 8.3%), but IMU and depth cues helped maintain vertical stability. The system delivers real-time, cost-effective localization in structured underwater cages and offers insights for improvements in dynamic marine conditions. Full article