Search Results (344)

Background: Attachments are essential components in clear aligner therapy, enhancing retention and improving the predictability of tooth movements. Mechanical and wear properties of the composite resins used for attachment reproduction are critical to maintaining their integrity and shape over time. This study aimed to evaluate and compare the mechanical properties, thermal behavior, and wear performance of the hybrid composite Aligner Connect (AC) and the flowable resin (Connect Flow, CF). Methods: Twenty samples (ten AC and ten CF) were reproduced. All specimens underwent differential scanning calorimetry (DSC), combustion analysis, flat instrumented indentation, compression stress relaxation tests, and tribological analysis. A 3D wear profile reconstruction was performed to assess wear surfaces. Results: DSC and combustion analyses revealed distinct thermal transitions, with CF showing significantly lower Tg values (103.8 °C/81.4 °C) than AC (110.8 °C/89.6 °C) and lower residual mass after combustion (23% vs. 61%), reflecting reduced filler content and greater polymer mobility. AC exhibited superior mechanical properties, with higher maximum load (585.9 ± 22.36 N) and elastic modulus (231.5 ± 9.1 MPa) than CF (290.2 ± 5.52 N; 156 ± 10.5 MPa). Stress relaxation decrease was less pronounced in AC (18 ± 4%) than in CF (20 ± 4%). AC also showed a significantly higher friction coefficient (0.62 ± 0.060) than CF (0.55 ± 0.095), along with greater wear volume (0.012 ± 0.0055 mm³ vs. 0.0070 ± 0.0083 mm³) and maximum depth (36.88 ± 3.642 µm vs. 17.91 ± 3.387 µm). Surface roughness before wear was higher for AC (Ra, 0.577 ± 0.035 µm; Rt, 4.369 ± 0.521 µm) than for CF (Ra, 0.337 ± 0.070 µm; Rt, 2.862 ± 0.549 µm). After wear tests, roughness values converged (Ra, 0.247 ± 0.036 µm for AC; Ra, 0.236 ± 0.019 µm for CF) indicating smoothened and similar surfaces for both composites. Conclusions: The hybrid nanocomposite demonstrated greater properties in terms of stiffness, load-bearing capacity, and structural integrity when compared with flowable resin. Its use may ensure more durable attachment integrity and improved aligner–tooth interface performance over time. Full article

Intertrochanteric fractures in the elderly present complex challenges due to poor bone quality and comorbidities. Cephalomedullary (CM) nails offer biomechanical advantages that support early mobilization, yet complications such as cutout, implant failure, and malalignment persist. This review examines the effectiveness of CM nail fixation in geriatric extracapsular hip fractures and introduces the RESCUE technique—a structured, mnemonic-based approach aimed at improving surgical outcomes and reducing common complications. RESCUE stands for Reduce, Entry point, Screw, Compress, Unleash traction, and Enhance full-weight bearing. This six-step framework addresses the critical elements of fixation, including precise reduction, optimal entry point selection, central screw placement, controlled fracture compression, cautious traction management, and early mobilization. Case illustrations of frequent failure patterns underscore the practical application of the RESCUE technique. By following this systematic approach, surgeons can enhance construct stability, minimize failure risk, and promote functional recovery in elderly patients. Full article

Mineral characterization of gold-bearing metasomatites in the Khaptasynnakh ore zone of the Anabar Shield is provided in detail. The following ore formation sequence of mineral associations in the Khaptasynnakh zone was found: pyrite and pyrrhotite → gersdorffite and molybdenite → chalcopyrite, sphalerite, and galena → bornite and chalcocite → tellurides, native gold, stibnite, cinnabar, and native bismuth. Native gold is characterized by varying fineness (550 to 926‰) and Cu impurity (up to 7.87%) values. Most often, it forms symplectite intergrowths with Au telluride–calaverite. Native gold and Au tellurides showed inclusions of chalcocite, bornite, altaite, tellurobismuthite, rickardite, petzite, and clausthalite. A two-stage formation process of the examined gold is suggested: Low-fineness gold was introduced into the system during early potassium metasomatism, while higher-fineness gold related to silica metasomatism resulted from its additional mobilization by fluid during late-stage formation. The low-temperature gold–telluride association observed in the mineral paragenesis of ore-bearing rocks, as well as its inclusions in native gold, suggests epithermal gold–telluride mineralization. Mineral inclusions examined in placer gold validate a genetic relation between the examined ores and gold placers in the Khaptasynnakh ore zone. Full article

This study presents the design and microstructural investigation of a single-crystal (SX) Re-bearing high-entropy superalloy (HESA-X1) featuring a thermally stable γ–γ′–γ hierarchical microstructure. The alloy exhibits FCC γ nanoparticles embedded within L1₂-ordered γ′ precipitates, themselves distributed in a γ matrix, with the suppression of detrimental topologically close-packed (TCP) phases. To elucidate solidification behavior and phase stability, Scheil–Gulliver and TC-PRISMA simulations were conducted alongside SEM and XRD analyses. Near-atomic scale analysis in 3D using Atom Probe Tomography (APT) revealed pronounced elemental partitioning, with Re strongly segregating to the γ matrix, while Al and Ti were preferentially enriched in the γ′ phase. Notably, Re demonstrated a unique partitioning behavior compared to conventional superalloys, facilitating the formation and stabilization of γ nanoparticles during two-step aging (Ag-2). These γ nanoparticles significantly contribute to improved mechanical properties. Long-term aging (up to 200 h) at 750–850 °C confirmed exceptional phase stability, with minimal coarsening of γ′ and retention of γ nanoparticles. The coarsening rate constant K of γ′ at 750 °C was significantly lower than that of Re-free HESA, confirming the diffusion-suppressing effect of Re. These findings highlight critical roles of Re in enhancing microstructural stability by reducing atomic mobility, enabling the development of next-generation HESAs with superior thermal and mechanical properties for high-temperature applications. Full article

In this paper, we investigate the target-approaching control problem for a discrete-time first-order vehicle system where the target area is modeled as a static circular region. In the absence of absolute bearing or position information, we propose a simple local controller that relies solely on range measurements to the target obtained at two consecutive sampling instants. Specifically, if the measured distance decreases between two successive samples, the vehicle maintains a constant velocity; otherwise, it rotates its velocity vector by an angle of $\pi /2$ in the clockwise direction. This control strategy guarantees convergence to the target region, ensuring that the vehicle’s velocity direction remains unchanged in the best-case scenario and is adjusted at most three times in the worst case. The effectiveness of the proposed method is theoretically established and further validated through outdoor experiments with a mobile vehicle. Full article

The formation of acidic goaf water in abandoned coal mines poses significant environmental threats, especially in karst regions where the risk of groundwater contamination is heightened. This study investigates the geochemical processes responsible for the generation of acidic water through batch and column leaching experiments using coal mine surrounding rocks (CMSR) from Yangquan, China. The coal-bearing strata, primarily composed of sandstone, mudstone, shale, and limestone, contain high concentrations of pyrite (up to 12.26 wt%), which oxidizes to produce sulfuric acid, leading to a drastic reduction in pH (approximately 2.5) and the mobilization of toxic elements. The CMSR samples exhibit elevated levels of arsenic (11.0 mg/kg to 18.1 mg/kg), lead (69.5 mg/kg to 113.5 mg/kg), and cadmium (0.6 mg/kg to 2.6 mg/kg), all of which exceed natural crustal averages and present significant contamination risks. The fluorine content varies widely (106.1 mg/kg to 1885 mg/kg), with the highest concentrations found in sandstone. Sequential extraction analyses indicate that over 80% of fluorine is bound in residual phases, which limits its immediate release but poses long-term leaching hazards. The leaching experiments reveal a three-stage release mechanism: first, the initial oxidation of sulfides rapidly lowers the pH (to between 2.35 and 2.80), dissolving heavy metals and fluorides; second, slower weathering of aluminosilicates and adsorption by iron and aluminum hydroxides reduce the concentrations of dissolved elements; and third, concentrations stabilize as adsorption and slow silicate weathering regulate the long-term release of contaminants. The resulting acidic goaf water contains extremely high levels of metals (with aluminum at 191.4 mg/L and iron at 412.0 mg/L), which severely threaten groundwater, particularly in karst areas where rapid cross-layer contamination can occur. These findings provide crucial insights into the processes that drive the acidity of goaf water and the release of contaminants, which can aid in the development of effective mitigation strategies for abandoned mines. Targeted management is essential to safeguard water resources and ecological health in regions affected by mining activities. Full article

In recent years, there has been a growing interest in the frictional anisotropy of snake scale-inspired surfaces, especially its potential applications in enhancing the bearing capacity of foundations (piles, anchor elements, and suction caissons) and reducing materials consumption and installation energy. This study first investigated the frictional properties and surface morphologies of the ventral scales of Cantor’s rat snakes (Ptyas dhumnades). Based on the findings on the snake scales, a novel snakeskin-inspired geosynthetic reinforcement (SIGR) is developed using 3D-printed polylactic acid (PLA). A series of pullout tests under different normal loads (25 kPa, 50 kPa, and 75 kPa) were performed to analyze the pullout behavior of SIGR in sandy soil. Soil deformation and shear band thickness were measured using Particle Image Velocimetry (PIV). The results revealed that the ventral scales of Ptyas dhumnades have distinct thorn-like micro-protrusions pointing towards the tail, which exhibit frictional anisotropy. A SIGR with a unilateral (one-sided) layout scales (each scale 1 mm in height and 12 mm in length) could increase the peak pullout force relative to a smooth-surface reinforcement by 29% to 67%. Moreover, the peak pullout force in the cranial direction (soil moving against the scales) was found to be 13% to 20% greater than that in the caudal direction (soil moving along the scales). The pullout resistance, cohesion, and friction angle of SIGR all showed significant anisotropy. The soil deformation around the SIGR during pullout was more pronounced than that observed with smooth-surface reinforcement, which suggests that SIGR can mobilize a larger volume of soil to resist external loads. This study demonstrates that SIGR is able to enhance the pullout resistance of reinforcements, thereby improving the stability of reinforced soil structures, reducing materials and energy consumption, and is important for the sustainability of geotechnical engineering. Full article

Background/Objectives: Acetabular fractures in older adults pose significant challenges due to bone fragility, complex fracture patterns, and increased comorbidities. Surgical management, including isolated open reduction and internal fixation (ORIF) and ORIF combined with acute total hip arthroplasty (THA) (combined hip procedure—CHP), have advanced considerably. Nevertheless, optimal postoperative rehabilitation and particularly weight-bearing (WB) recommendations remain controversial and inconsistent. This review aims to assess rehabilitation protocols, focusing on WB strategies following the surgical treatment of acetabular fractures in older adults. It also examines differences in WB restrictions by surgical technique (ORIF vs. CHP) and their impact on recovery, complications, reoperations, and mortality. Methods: A systematic review of PubMed, Embase, and the Cochrane Library (2006–2024) included studies involving patients aged ≥65 years treated surgically for displaced acetabular fractures. Data included WB protocols (full, partial, toe-touch), length of stay (LOS), healing, functional outcomes (mobility, Harris and Oxford Hip Scores), complications, reoperations, delayed THA, compliance, readmission, and mortality. Due to heterogeneity, findings were narratively synthesized. Risk of bias was assessed using ROBINS-I and RoB2. Results: Twenty studies involving 929 patients (530 isolated ORIF, 399 CHP) were analyzed. The overall mean follow-up was 3.5 years (range: 1–5.25 years). Postoperative WB protocols were reported in 19 studies (95%). Immediate full WB was permitted in 0% of isolated ORIF studies (0/13), with partial WB recommended by 62% (8/13) for durations typically between 6 and 12 weeks. On the other hand, immediate full WB was allowed in 53% (9/17) of CHP studies. Functional outcomes were moderate following isolated ORIF (mean HHS: 63–82 points), with delayed THA conversion rates ranging from 16.5% to 45%. CHP demonstrated superior functional outcomes (mean HHS: 70–92 points), earlier independent ambulation, and higher patient satisfaction (74–90%), yet increased orthopedic complications, including dislocations (8–11%) and implant loosening (up to 18%). LOS varied from 12 to 21 days (mean 16 days) for isolated ORIF and from 8 to 25 days (mean 17 days) for CHP. Readmission within 30 days was not explicitly reported in any study. Mortality at 1 year varied significantly (ORIF: 0–25%; CHP: 0–14%), increasing markedly at long-term follow-up (up to 42% ORIF, up to 70% CHP at five years). Compliance with WB restrictions was monitored in only two studies (11%). Conclusions: Postoperative rehabilitation after acetabular fracture surgery in older adults remains inconsistent and lacks standardization. Combining ORIF with acute THA may enable earlier weight-bearing and improved short-term function but carries risks such as dislocation and implant loosening. In contrast, isolated ORIF avoids these implant-related complications but often requires prolonged weight-bearing restrictions. Robust evidence is still missing. Future trials are essential to establish standardized protocols that balance mechanical protection and functional recovery. Full article

Osteoarthritis (OA) is a leading cause of disability worldwide and is characterized by the gradual degradation of articular cartilage in weight-bearing joints, notably the knees and hips. However, the primary morphological and anatomical determinants of the disease onset and progression remain unclear. This narrative overview examines how variations in cartilage thickness—traditionally viewed as a biomechanical protective feature—can paradoxically compromise metabolic homeostasis during prolonged sedentary behavior. Intriguingly, compelling evidence suggests that despite its superior load-bearing capacity, thicker cartilage faces greater challenges in solute transport, a limitation further exacerbated by the formation of diffusion-resistant boundary layers at the cartilage–fluid interface during immobilization. This phenomenon restricts nutrient influx and impedes waste clearance, leading to the accumulation of catabolic byproducts in deep cartilage zones and accelerated extracellular matrix breakdown, potentially influencing OA pathogenesis. By critically synthesizing current debates on mechanical loading with emerging data on metabolic dysregulation, particularly nutrient diffusion limitations, this analysis underscores the urgent need for targeted investigation of synovial–cartilage interface dynamics and chondrocyte metabolism under low-motion conditions. This study further advocates for strategic research focusing on often-overlooked, silent metabolic imbalances among sedentary populations and recommends early-intervention strategies, such as periodic joint mobilization, ergonomic adaptations, and public-health campaigns, to reduce prolonged sitting, preserve joint function, and guide more effective prevention and management approaches for non-traumatic OA in contemporary contexts. Full article

Background/Objectives: High-energy trauma to the lower limb often results in extensive soft tissue loss with exposure of critical structures, posing a serious threat to limb viability. Early and effective coverage is crucial to prevent infection, promote bone healing, and preserve function. This report presents the use of a latissimus dorsi free flap for circumferential soft tissue reconstruction following a severe crush injury. Methods: We describe the case of a young female patient who sustained a high-energy crush trauma with a comminuted, displaced fracture of the middle and distal third of the tibia and complete circumferential soft tissue loss. Due to the extent and location of the defect, a latissimus dorsi free flap was selected for reconstruction. The surgical technique, microsurgical anastomosis, postoperative care, and rehabilitation protocol are detailed. Results: The latissimus dorsi flap provided reliable coverage of the entire defect, protected the underlying bone and hardware, and promoted wound healing. No major complications were observed. Functional recovery was satisfactory, with progressive weight-bearing and joint mobility achieved during follow-up. Conclusions: In complex lower limb injuries with extensive soft tissue damage, free flap transfer remains a key strategy for limb salvage. The latissimus dorsi flap, due to its size, reliability, and versatility, represents a valuable option for circumferential coverage and restoration of limb function following high-energy trauma. Full article

Background: The effectiveness of hip hemiarthroplasty in managing femoral neck fractures in individuals with cerebral palsy has seldom been reported. Objectives: Given the complex neuromuscular issues associated with cerebral palsy (CP), this retrospective study aims to document the outcomes and characterize the complications of hip hemiarthroplasty for fractures of the femoral neck in a series of patients with CP, emphasizing the role of precision medicine in management. Methods: Six cases of hip hemiarthroplasty in six male patients with cerebral palsy and displaced femoral neck fractures have been reviewed in this study. The patients’ mean age at the time of surgery was 55.6 ± 14.1 years (range, 33–71). All the patients were independent indoor ambulators before their femoral neck fracture and had various medical comorbidities. Five patients had intellectual disabilities. Results: The mean clinical and radiographic follow-ups for the patients included in this series were 91.5 and 71.3 months, respectively. All the patients developed significant heterotopic ossification (HO) around the operated hip, which was observed as early as the second week postoperatively on radiographs. HO progressed throughout the follow-up for all the patients. One patient had an early postoperative dislocation with femoral stem loosening, which was managed by implant revision. Another patient had an acetabular protrusion, leading to the loss of their weight-bearing ability and mobility due to pain. Four patients were deceased at a mean of 86.5 months after the index surgery. Conclusions: After considering the preliminary evidence provided with this small case series, this study suggests the overall guarded outcomes of hip hemiarthroplasty in patients with CP. Given the 100% rate of heterotopic ossification, a precision medicine framework with consideration for HO prophylaxis may be recommended after hip hemiarthroplasty in patients with CP. It may also be reasonable to scrutinize a personalized risk assessment approach in this patient subset regarding decision making, surgical approach, and rehabilitation program. The clinical outcomes and the risks of complications following hemiarthroplasty should be sensibly presented to patients with cerebral palsy and their caregivers to achieve reasonable postoperative expectations. Full article

To improve the traction performance of mobile mechanisms on soft ground, such as paddy fields, tidal flats, and swamps, a mallard (Anas platyrhynchos) foot was adopted as a bionic prototype to explore the influence and contribution of the plantar morphology of the toes and webbing on the anti-subsidence function during its locomotion on wet and soft substrates and to apply this to the bionic design of high-traction wheel grousers. A handheld three-dimensional laser scanner was used to scan the main locomotion postures of a mallard foot during ground contact, and the Geomagic Studio software was utilized to repair the scanned model. As a result, the main three-dimensional geometric models of a mallard foot during the process of touching the ground were obtained. The plantar morphology of a mallard foot was divided into three typical parts: the plantar irregular edge curve, the lateral webbing surface, and the medial webbing surface. The main morphological feature curves/surfaces were extracted through computer-aided design software for the fitting and construction of a mathematical model to obtain the fitting equations of the three typical parts, and the mathematical model construction of the plantar irregular morphology of the mallard foot was completed. In order to verify the sand-fixing and flow-limiting characteristics of this morphological feature, based on the discrete element method (DEM), the numerical simulation of the interaction between the plantar surface of the mallard foot and sand particles was carried out. The simulation results show that during the process of the mallard foot penetration into the loose medium, the lateral and medial webbing surfaces cause the particles under the foot to mainly move downward, effectively preventing the particles from spreading around and significantly enhancing the solidification effect of the particles under the sole. Based on the principle and technology of engineering bionics, the plantar morphology and movement attitude characteristics of the mallard were extracted, and the characteristics of concave middle and edge bulge were applied to the wheel grouser design of paddy field wheels. Two types of bionic wheel grousers with different curved surfaces were designed and compared with the traditional wheel grousers of the paddy field wheel. Through pressure-bearing simulation and experiments, the resistance of different wheel grousers during the process of penetrating into sand particles was compared, and the macro–micro behaviors of particle disturbance during the pressure-bearing process were analyzed. The results show that a bionic wheel grouser with unique curved surfaces can well encapsulate sand particles at the bottom of the wheel grouser, and it also has a greater penetration resistance, which plays a crucial role in improving the traction performance of the paddy field wheel and reducing the disturbance to the surrounding sand particles. This paper realizes the transformation from the biological model to the mathematical model of the plantar morphology of the mallard foot and applies it to the bionic design of the wheel grousers of the paddy field wheels, providing a new solution for improving the traction performance of mobile mechanisms on soft ground. Full article

The global dissemination of plasmid-mediated mcr genes, which confer resistance to the last-resort antibiotic colistin, represents a critical public health challenge driven by the interplay of clinical, agricultural, and environmental factors. This review examines the genetic and ecological dynamics of mcr-bearing plasmids, focusing on their role in disseminating colistin resistance across diverse bacterial hosts and ecosystems. Key plasmid families demonstrate distinct evolutionary strategies, including IncI2, IncHI2, and IncX4. IncI2 plasmids favor stability in livestock and clinical settings. IncHI2 plasmids, on the other hand, leverage transposons to co-select for multidrug resistance, while IncX4 plasmids achieve global dissemination through streamlined, conjugation-efficient architectures. The pervasive spread of mcr genes is exacerbated by their integration into chromosomes via mobile genetic elements and co-selection with resistance to other antibiotic classes, amplifying multidrug-resistant phenotypes. Environmental reservoirs, food chains, and anthropogenic practices further facilitate cross-niche transmission, underscoring the interconnectedness of resistance under the One Health framework. Addressing this crisis requires coordinated strategies, including reducing colistin misuse in agriculture, enhancing surveillance of high-risk plasmid types, and fostering international collaboration to preserve antimicrobial efficacy and mitigate the threat of untreatable infections. Full article

Cancer-associated sarcopenia is closely linked to the prognosis of cancer patients, making its management a critical aspect of cancer treatment. Branched-chain amino acids (BCAAs) are known to promote skeletal muscle growth in healthy individuals; however, their efficacy in cancer patients remains controversial. In this study, we investigated the effects of BCAAs on cancer-associated sarcopenia to identify the underlying mechanisms that may suppress their effectiveness. In both a mouse cachexia model and an in vitro cachexia model, BCAAs did not significantly reduce oxidative stress, improve oxidative phosphorylation, suppress cytokine production, or enhance muscle mass and maturation, as observed in non-cancer-bearing models. Furthermore, treatment with 5-fluorouracil exacerbated sarcopenia in the mouse cachexia model, independent of tumor weight reduction, and this deterioration was not ameliorated by a BCAA-supplemented diet. The ineffectiveness of BCAAs was attributed to impaired BCAA catabolism, characterized by the decreased expression of branched-chain α-ketoacid dehydrogenase (BCKD) and increased levels of its inactive phosphorylated form, which were driven by elevated expression of BCKD kinase. These metabolic alterations were induced by high-mobility group box-1 (HMGB1). Notably, caprylic acid reversed these impairments in BCAA metabolism, thereby restoring BCAA efficacy. Our findings suggest that enhancing BCAA metabolism may improve their therapeutic potential in the treatment of cancer-associated sarcopenia. Full article

Background: Although cemented total knee arthroplasty (TKA) is considered the standard fixation technique, the emerging trend toward cementless fixation has created the need for a detailed comparison. In a previous study, we reported the 5-year results comparing cementless and hybrid cemented TKAs using the same implant design. The purpose of this study was to assess the long-term follow-up at a minimum of 10 years. Methods: A retrospective analysis was performed on 120 TKAs (60 cementless, 60 hybrid cemented) conducted between 2003 and 2007 using the e.motion posterior cruciate-retaining knee prosthesis with a floating-platform mobile polyethylene bearing (Aesculap, Tuttlingen, Germany). Demographic and clinical data were collected; radiographic follow-up was performed with attention to signs of loosening, while complications and revision surgery were assessed using competing risk analysis. Operative time was recorded as an indicator of surgical efficiency. Results: At 10 years, 59 TKAs (54 patients) were available for long-term follow-up. Both fixation groups demonstrated significant improvement in Knee Society Scores (KSSs) compared to preoperative values (p < 0.001). However, there was no significant difference in KSSs between the two groups at 10 years follow-up (p = 0.480). The 10-year cumulative incidence of revision was 8.4% in both groups (p = 0.721), and that of aseptic loosening was identical at 3.4% (p = 0.967). Although radiolucent lines were noted in three tibial components of the cementless group, the difference was not statistically significant (p = 0.075). Notably, the cementless group demonstrated a significantly shorter operative time with a mean difference of 10 min (p = 0.017). Conclusions: At a minimum follow-up of 10 years, there were no significant differences between the hybrid cemented and cementless groups in revision rates, cumulative incidences, clinical scores, or radiological signs of loosening, confirming the long-term effectiveness of both fixation methods in clinical practice. Full article