Search Results (84)

Earth fill dams are susceptible to internal erosion and instability when founded over cavity-prone formations such as gypsum or karstic limestone. Subsurface voids can significantly compromise dam performance, particularly under seismic loading, by altering seepage paths, raising pore pressures, and inducing structural deformation. This study examines the influence of cavity presence, location, shape, and size on the behavior of zoned earth dams. A 1:25 scale physical model was tested on a uniaxial shake table under varying seismic intensities, and seepage behavior was observed under steady-state conditions. Numerical simulations using SEEP/W and QUAKE/W in GeoStudio complemented the experimental work. Results revealed that upstream and double-cavity configurations caused the greatest deformation, including crest displacements of up to 0.030 m and upstream subsidence of ~7 cm under 0.47 g shaking. Pore pressures increased markedly near cavities, with peaks exceeding 2.7 kPa. Irregularly shaped and larger cavities further amplified these effects and led to dynamic factors of safety falling below 0.6. In contrast, downstream cavities produced minimal impact. The excellent agreement between experimental and numerical results validates the modeling approach. Overall, the findings highlight that cavity geometry and location are critical determinants of dam safety under both static and seismic conditions. Full article

Medium- and large-scale heat sinks are critical for thermal load management in high-performance systems. However, their high heat flux densities and limited space complicate cooling, leading to risks of overheating, performance degradation, or failure. This study employs the Cascaded Lattice Boltzmann Method (CLBM) to enhance their thermal performance. This numerical approach is known for being stable, accurate when dealing with complex boundaries, and efficient when computing in parallel. The numerical code was validated against a benchmark configuration and an experimental setup to ensure its reliability and accuracy. While previous studies have explored mixed convection in cavities or heat sinks, few have addressed configurations involving side air injection and boundary conditions periodicity in the transition-to-turbulent regime. This gap limits the understanding of realistic cooling strategies for compact systems. Focusing on mixed convection in the transition-to-turbulent regime, where buoyancy and forced convection interact, the study investigates the impact of Rayleigh number values ($5\times {10}^7$ to $5\times {10}^8$) and Reynolds number values (${10}^3$ to $3\times {10}^3$) on heat transfer. Simulations were conducted in a rectangular cavity with periodic boundary conditions on the vertical walls. Two heat sources are located on the bottom wall ($T_h$ = 50 °C). Two openings, one on each side of the two hot sources, force a jet of fresh air in from below. An opening at the level of the cavity ceiling’s axis of symmetry evacuates the hot air. Mixed convection drives the flow, exhibiting complex multicellular structures influenced by the control parameters. Calculating the average Nusselt number (Nu) across the surfaces of the heat sink reveals significant dependencies on the Reynolds number. The proposed correlation between Nu and Re, developed specifically for this configuration, fills the current gap and provides valuable insights for optimizing heat transfer efficiency in engineering applications. Full article

This study numerically investigates unsteady natural convection (NC) heat transfer (HT) and entropy generation (E_gen) in trapezoidal cavities filled with two thermally stratified fluids. Both air-filled and water-filled configurations are analyzed to evaluate and compare their thermal performance under varying conditions. The cavities are characterized by a heated base, thermally stratified sloped walls, and a cooled top wall. The governing equations are numerically solved using the finite volume (FV) approach. The study considers a Prandtl number (Pr) of 0.71 for air and 7.01 for water, Rayleigh numbers (Ra) ranging from 10³ to 5 × 10⁷, and an aspect ratio (AR) of 0.5. Flow behavior is examined through various parameters, including temperature time series (TTS), average Nusselt number (Nu), average entropy generation (E_avg), average Bejan number (Be_avg), and ecological coefficient of performance (ECOP). Three bifurcations are identified during the transition from steady to chaotic flow for both fluids. The first is a pitchfork bifurcation, occurring between Ra = 10⁵ and 2 × 10⁵ for air, and between Ra = 9 × 10⁴ and 10⁵ for water. The second, a Hopf bifurcation, is observed between Ra = 4.7 × 10⁵ and 4.8 × 10⁵ for air, and between Ra = 10⁵ and 2 × 10⁵ for water. The third bifurcation marks the onset of chaotic flow, occurring between Ra = 3 × 10⁷ and 4 × 10⁷ for air, and between Ra = 4 × 10⁵ and 5 × 10⁵ for water. At Ra = 10⁶, the average HT in the air-filled cavity is 85.35% higher than in the water-filled cavity, while E_avg is 94.54% greater in the air-filled cavity compared to water-filled cavity. At Ra = 10⁶, the thermal performance of the cavity filled with water is 4.96% better than that of the air-filled cavity. These findings provide valuable insights for optimizing thermal systems using trapezoidal cavities and varying working fluids. Full article

Background: Odontogenic cysts can damage the surrounding bone tissue as they grow, making it essential to implement effective regenerative strategies tailored to each patient. Personalised approaches in oral surgery, such as selecting the most suitable bone graft materials, can lead to improved treatment outcomes. Filling the bone defect created after cyst removal, root resection, or extraction with a bone graft material can stabilise the weakened tooth and promote faster bone regeneration. This article shares our experiences with the therapeutic effects of albumin-coated bone allograft (BoneAlbumin^®) placed in the bone defect following cyst removal in the oral cavity, compared to cases where the defect was left untreated (controls). Methods: The study involved thirty patients who underwent the removal of maxillary odontogenic cysts. In 15 of these patients, the bone defect was filled with albumin-coated bone allograft (BoneAlbumin^®, OrthoSera, Budapest, Hungary). In the control group, which consisted of 15 patients, the defect was left untreated. A consistent surgical protocol was adhered to throughout the study. Follow-up periapical X-rays were taken immediately after surgery as well as at 6 and 12 weeks post-surgery, using a standardised template. These images were used to assess the shrinkage and healing of the defect caused by the cyst. Measurements were adjusted to reference points to account for potential distortions in the X-rays. Results: The control and study groups exhibited no statistically significant differences in their basic parameters. Additionally, there was no notable difference in the sizes of postoperative defects between the two groups. However, statistical analysis revealed a significant difference in the changes in defect size (∆defect size) between the groups at both 6 weeks (p < 0.000001) and 12 weeks (p = 0.000296). This suggests that the BoneAlbumin^®-graft group experienced significantly greater changes in defect size over time. Conclusions: The use of BoneAlbumin^® graft leads to a markedly better reduction in defect size as time progresses, although these changes have only been compared to graft-free healing. Full article

This study presents an elastic one-dimensional numerical model to simulate the filling process of a large-scale, partially drained pipeline with an undulating profile, incorporating bypass systems. The model uses the Method of Characteristics to solve water hammer equations and integrates the Discrete Gas Cavity Model to capture column separation effects. Validation is performed using two experimental test rigs and comparisons with existing numerical models, showing RMSE values between 1.06 and 7.95. The results highlight three key findings: (1) oversized bypasses generate severe transient pressures; (2) effective air management enables higher filling flow rates, significantly reducing filling time; and (3) bypass lines help dampen pressure fluctuations, with a notable drop in $∆H$ from 528 m to 6.8 m occurring in stage b, following the release of trapped air. Additionally, this study challenges the practicality of the AWWA’s recommended pipeline filling velocity limit of 0.3 m/s, showing that strict adherence to this guideline is often unrealistic for large-scale systems. Overall, the findings emphasize the need for a balanced design approach that reduces transient risks while maintaining operational efficiency in large-scale pipelines. Full article

A passively Q-switched Thulium-doped fiber laser based on glycerin as the saturable absorber is experimentally demonstrated for the first time. The saturable absorber consists of two FC/PC connectors aligned within a mechanical fiber-fiber coupler, with the intervening gap filled with glycerin. Such a saturable absorber is integrated into a compact ring cavity, enabling passive Q-switched laser operation. Starting at a minimum pump power of 1.7 W, Q-switched pulses with a central wavelength of 1946 nm are obtained. At the maximum pump power of 2.4 W, the laser generates pulses with a duration of approximately 2 µs, a repetition rate of 26.7 kHz, and a pulse energy of 1.08 µJ. To the best of our knowledge, this is the first demonstration of passively Q-switched laser operation utilizing a glycerin-based saturable absorber for generating pulsed emission at the 2-µm wavelength region. This breakthrough represents a significant advancement in fiber laser technology, introducing a novel and efficient approach to pulse generation. Full article

The motion of a copter with a suspended payload in a vertical plane is considered. The payload has a spherical shape and contains a concentric spherical cavity partially filled with ideal liquid. The system is subjected to horizontal stationary wind. The aerodynamic load on the payload is described within the framework of a quasi-steady approach. The dynamics of the liquid are simulated using the phenomenological pendulum model. The points of this study are the controllability and observability of a stationary flight of a copter with the payload. A control strategy is proposed, which aims to bring the system from a certain initial state to a certain final state, such that the center of mass of the copter moves along a given sufficiently smooth curve. The control is designed to ensure the suppression of oscillations of the payload and the liquid along the entire trajectory. Full article

Background: Syringomyelia is a complex neurological disorder characterized by a fluid-filled cavity (syrinx) within the spinal cord, frequently resulting from altered cerebrospinal fluid (CSF) dynamics. While its clinical manifestations are diverse, orthopedic complications such as scoliosis, pes cavus, and Charcot arthropathy may represent early diagnostic clues yet are often under-recognized. Methods: This comprehensive review synthesizes the current literature on the pathophysiology, clinical presentation, diagnostic strategies, and management approaches of syringomyelia, with a specific emphasis on its orthopedic manifestations. Additionally, we present a detailed case of neuropathic shoulder arthropathy associated with advanced syringomyelia. Results: Orthopedic involvement in syringomyelia includes progressive spinal deformities and neurogenic joint destruction, particularly affecting the shoulder and elbow. Scoliosis is frequently observed, especially in association with Chiari malformations, and may precede neurologic diagnosis. Charcot joints result from impaired proprioception and protective sensation. The case presented illustrates the diagnostic challenges and therapeutic dilemmas in managing advanced neuro-orthopedic complications in syringomyelia. Conclusions: Syringomyelia should be considered in the differential diagnosis of atypical musculoskeletal presentations. Early recognition and multidisciplinary management are essential to prevent irreversible orthopedic sequelae. Conservative treatment remains the mainstay in stable cases, while surgery is reserved for progressive disease. Orthopedic assessment plays a pivotal role in the diagnostic pathway and long-term care of affected patients. Full article

With the development of prefabricated buildings, complex-shaped cement products, represented by heating-type elevated floors, have appeared on the market. These cement products can only be produced by the pouring method, with low efficiency and poor precision. Among the existing processing methods for preparing cement products, compression dewatering offers the greatest ability to produce cement products with complex shapes. However, the pressed mixing material comprises a plastic fresh mortar, which inherently lacks fluidity, making it difficult to completely fill the cavity of the shaped mold. Few studies have been conducted on the experimental method and design ratios of mortar for the compression dewatering process in the industry, with no effective solution. To achieve the efficient production of complex-shaped cement products, this study explored the experimental method of testing the strength and flowability of mortar formed through compression dewatering as the forming process. Mortar ratios suitable for producing complex-shaped cement products using the compression dewatering process were determined, the relationship between material rheology and product forming performance was analyzed, and the influence of the compression process on the strength and micro-properties was studied. Finally, a cement-based heating-type elevated floor forming technology was developed, offering a novel approach for the efficient forming of complex-shaped cement products. Full article

Background: Curettage represents a reliable therapeutic option for large-sized benign and locally aggressive bone tumors. In cases of impending fractures, internal fixation with plates and screws can be necessary to stabilize the treated bone after curettage. Metal plates have been the only fixation devices available on the market for decades, but Carbon-fiber-reinforced polyetheretherketone (CFR-PEEK) now represents an alternative in orthopedic oncology. Methods: We reviewed our patients with benign or locally aggressive bone tumors treated with curettage and fixation with CFR-PEEK plates. Plate length and curettage technique were chosen considering the characteristics of each lesion. We recorded the size and location of the lesions, adjuvant treatments and fillers used after curettage, complications, and local recurrences. Postoperative functionality was assessed using the MSTS score. Results: Forty cases were included in our study. The tumors were located in the distal femur (19 cases), femur shaft (1), humerus (17), or proximal tibia (3). Local adjuvants were used in 20 cases. Cavities were filled with bone allografts in 30 cases and cement in 10 cases. Only four cases suffered postoperative complications, and two developed local recurrences. The mean postoperative follow-up was 29.2 months. The mean postoperative upper and lower limb MSTS was 28.0 and 26.7, respectively. Conclusions: After an accurate curettage and an adequate filling of the resulting bone gap, CFR-PEEK plates can provide good mechanical resistance, and their radio-transparency can ease the early diagnosis of local recurrences. CFR-PEEK plates should be considered in selected cases, in a personalized surgical approach. Full article

Background: Dental caries is one of the most common oral infections observed worldwide. It is defined as a multifactorial dynamic disease-causing mineral loss of dental hard tissue, which is identified by the caries lesion. Treatment of the caries lesion involves filling the cavity or removing the damaged tooth. Then, the decayed, missing, and filled teeth (DMFT) index is the simplest and most commonly used index to assess the dental caries status. Salivary glands are estrogen dependent and, after menopause, the changes in salivary flow and saliva consistency produce xerostomia, hyposiale, or dryness, common findings among postmenopausal women. Since saliva plays a fundamental role in caries prevention, the postmenopausal decline in salivary secretion may contribute to increased caries incidence. The aim of this systematic review and meta-analysis was to answer the following PICO question: In adult women (P), does the presence of menopause (I), compared to its absence (C), influence dental caries status, assessed using the DMFT index (O)? Methods: The study adhered to PRISMA guidelines. A systematic search was conducted in PubMed/MEDLINE, Scopus, and EMBASE databases. For each study, characteristics and mean difference (MD) with 95% CI were extracted. Meta-analyses were performed using the Revman software (v. 5.4) to calculate pooled MD and 95% CI. Random-effects model meta-analysis was performed. Risk of bias was evaluated using the Newcastle–Ottawa Scale adapted for cross-sectional studies. To estimate variance and heterogeneity between trials, the Higgins I² test was used. The certainty level of the evidence was determined through the GRADE approach. Results: Seven studies fulfilled the inclusion criteria, including 4396 postmenopausal women and 5131 control women. Meta-analysis showed an overall MD = 3.13 (95% CI = 2.12–4.15; p < 0.00001), which suggest that postmenopausal women had a DMFT index 3 units higher than the control group. Conclusions: Menopause was significantly associated with worse dental caries status, probably due to declining estrogen levels affecting salivary function. Further research is needed to confirm mechanisms and evaluate preventive strategies like hormone replacement therapy. Full article

The increasing power density of high-performance electronic devices poses significant thermal management challenges. Vapor chambers (VCs) offer efficient heat dissipation, but traditional manufacturing methods limit their structural precision and performance. This study investigates the thermal performance of VCs fabricated with additive manufacturing (AM), featuring triply periodic minimal surface (TPMS) Gyroid capillary structures at two fill ratios under varying thermal loads. Enhanced thermal stability and performance were observed in the higher fill ratio, particularly under higher heat loads, whereas the lower fill ratio excelled under low-heat conditions, achieving a thermal resistance as low as 0.3688 K/W at an 80 W heat load. Additionally, the research explored the advantages and challenges of horizontal and vertical printing techniques in VC fabrication. Horizontal printing was found to compromise cavity volume due to necessary support structures, whereas vertical printing enhanced mass production feasibility and maintained effective vapor circulation. This study proposes a novel approach using AM to manufacture VCs as a monolithic structure. By eliminating the need for welding, this method ensures seamless integration of the capillary structure with the housing, thereby avoiding issues related to poor contact or welding-induced damage. The study confirmed a 75% reduction in thermal resistance in VCs with capillary structures compared to those without under similar conditions, highlighting the significant potential of integrating precisely designed capillary structures and additive manufacturing in improving vapor chamber performance for advanced thermal management applications. Full article

A novel water-soluble root canal filling material based on sodium iodide (NaI) has been developed to overcome the limitations of existing iodine-based formulations. However, the biological stability of this approach in animal studies remains unverified. This study evaluated the biocompatibility of NaI compared to commercial root canal filling materials (Calcipex II and Vitapex^®) in pulpectomized canine teeth to assess its clinical applicability. Following a four-week observation period, none of the experimental groups exhibited tooth mobility or fistula formation. Radiographic and micro-CT analyses revealed no radiolucency in periapical lesions. Histopathologic evaluation demonstrated the absence of inflammatory responses in periapical regions across all material groups, with histological inflammation scoring 0. High-magnification histological examination of periapical areas showed well-preserved periodontal ligament tissue in all groups. Despite certain limitations of NaI-based fillings in the pulp cavity, including loss of radiopacity and tooth discoloration, NaI demonstrates potential as a safe and effective alternative for pulp filling material, particularly due to its minimal risk of root resorption and inflammatory response. Full article

Applications including aircraft systems and electronics cooling depend on effective heat transfer. This study investigates magnetohydrodynamic (MHD) free convection and thermal radiation for heat transfer in a circular cavity filled with multi-walled carbon nanotube (MWCNT) nanofluid and containing a square obstruction. This study examines the impact of the internal geometry on heat transfer and fluid flow dynamics under three distinct boundary conditions, and it presents a comprehensive analysis based on a wide range of Hartmann (Ha) and Rayleigh (Ra) numbers. MWCNT nanofluid with high thermal conductivity was employed to enhance heat transfer efficiency, using a solid volume fraction (SVF) of 4% for MWCNTs and assuming Newtonian behavior for computational simplification. Magnetic properties were imparted to the nanofluid by assuming the dispersion of carbon nanotubes in a base fluid containing magnetic nanoparticles. Other walls were insulated, the bottom wall was heated, and a magnetic field (MF) with Ha ranging from 0 to 100 was applied. It was observed that raising Ra from 103 to 106 improved the Nusselt number (Nu) from 0.08 to 7.1 using the Galerkin finite element method. Ha increased from 0 to 100 and reduced Nu by 35%. Three boundary conditions for the square body showed that the heated conditions provided the largest Nu. By means of an increase in SVF from 0 to 0.04, the MWCNT nanofluid improved heat conductivity by 18%. Radiation effects with the radiation parameter Rd = 0.5 increased heat transmission by 22%. These results underline the importance of considering MHD and nanofluid characteristics in maximizing heat transfer for commercial purposes, and the approaches employed in this study contribute to a deeper understanding of the behavior of thermal systems under the influence of MHD and internal geometry. Full article

Hypertrophic cardiomyopathy (HCM) is a heterogeneous group of heart muscle disorders that affects millions, with an incidence from 1 in 500 to 1 in 200. Factors such as genetics, age, gender, comorbidities, and environmental factors may contribute to the course of this disease. Diagnosis of HCM has improved significantly in the past few decades from simple echocardiographic evaluations to a more complex, multimodal approach embracing advanced imaging, genetic, and biomarker studies. This review focuses on Mavacamten, a selective allosteric inhibitor of cardiac myosin, as a pharmacological treatment for HCM. Patients with HCM experience pathological actomyosin interactions, leading to impaired relaxation and increased energy expenditure. Mavacamten decreases available myosin heads, reducing actomyosin cross-bridges during systole and diastole. By reducing the number of bridges left ventricular outflow tract pressure is normalized and cardiac cavities are filled. This mechanism enhances patient performance and alleviates symptoms such as chest pain and dyspnea. The results suggest the potential for Mavacamten to transform the treatment of obstructive hypertrophic cardiomyopathy. Studies to date have shown significant improvement in exercise capacity, symptom relief, and a reduction in the need for invasive procedures such as septal myectomy. Further studies are needed to confirm the clinical results. Full article