Search Results (4,625)

Background/Objectives: Dental caries continues to represent a major oral health concern in children, particularly in uncooperative patients, where effective sealant placement is often compromised. This study evaluated the long-term clinical performance of hydrophilic (UltraSeal XT hydro) and hydrophobic (Helioseal-F) resin-based sealants in uncooperative children aged 6–9 years, assessing retention and caries incidence over 24 months. Methods: In a split-mouth, double-blinded randomized controlled trial, 34 children (104 first permanent molars) were enrolled, with 31 participants (98 teeth) completing the study. Sealants were randomly assigned to hydrophilic or hydrophobic group, with assessments at 3, 6, 12, 18, and 24 months. Results: Complete retention declined progressively in both groups, from 59.2% to 2.0% in the hydrophilic group and from 42.9% to 0% in the hydrophobic group at 24 months, with no significant intergroup differences (p = 0.719). Caries-free rates decreased from 81.6% to 49.0% in the hydrophilic group and from 75.5% to 40.8% in the hydrophobic group (p = 0.293). Children with definitely negative behavior showed significantly lower retention at 6 and 12 months (p = 0.006 and p < 0.001) compared to those with negative behavior, although differences were not significant at 24 months. Conclusions: Overall, both sealants demonstrated comparable retention and cariostatic performance, indicating that material properties alone do not determine long-term success. Further research should focus on long-term follow-up and comparative evaluation of hydrophilic sealants in cooperative and uncooperative populations to better understand how patient behavior affects sealant performance. Full article

Multipath propagation presents a major challenge to acoustic communication, causing signal distortion, delay spread, and inter-symbol interference, which degrade data integrity. This study investigates the use of Orthogonal Frequency Division Multiplexing (OFDM) as a robust modulation strategy for communication in complex acoustic environments where radio frequency (RF) propagation is severely attenuated. Using a software-defined radio (SDR) platform implemented in GNU Radio, OFDM performance was experimentally evaluated against Binary Frequency Shift Keying (BFSK) and Binary Phase Shift Keying (BPSK) under simulated and real multipath conditions in materials including air, water, and steel. The results show that OFDM achieves consistently lower bit error rates (BERs) and greater resilience to multipath interference due to its sub-carrier orthogonality and cyclic-prefix structure. The research also highlights how the frequency selectivity and coherence bandwidth of acoustic channels influence modulation performance across different media. By implementing custom transducers and real-time baseband processing, the study demonstrates how software-defined acoustics can be adapted for highly reflective and frequency-dependent environments. The observed improvements in BER and signal stability validate OFDM’s effectiveness in maintaining data integrity despite time and frequency dispersion effects. These findings demonstrate that OFDM enables reliable acoustic data transmission across heterogeneous media and is well suited to sensor-network applications in RF-hostile environments such as railway infrastructure, sealed containers, and submerged systems. Future work will include quantitative channel characterisation—specifically measuring delay spread, coherence bandwidth, and impulse response profiles—to further optimise OFDM parameters and provide a generalisable framework for adaptive modulation in dynamic acoustic channels. Full article

Urban districts along major rivers are undergoing rapid transformation, yet long-term evidence on how redevelopment reshapes land cover and vegetation structure remains limited in post-socialist cities. This study examines the spatio-temporal evolution of land use and land cover (LULC) and vegetation dynamics along the Sava River corridor in Belgrade from 1990 to 2024. CORINE Land Cover (CLC) datasets were combined with Landsat-derived NDVI and MSAVI time series, while high-resolution Esri Wayback imagery was used for visual interpretation and qualitative corroboration of the detected land-cover and vegetation patterns. Beyond conventional NDVI/LULC assessments, the study integrates multi-decadal spectral trends with functional vegetation structure classification to evaluate canopy continuity and ecological configuration under contrasting redevelopment models. Results reveal a pronounced divergence between the two riverbanks. The left bank (New Belgrade) maintains stable land-cover composition and consistently higher NDVI and MSAVI values, indicating preserved green infrastructure and sustained canopy continuity. In contrast, the right bank (Belgrade Waterfront) experienced substantial land-cover conversion after 2006, with a statistically significant decline in vegetation greenness (NDVI −0.020 dec⁻¹, p < 0.001) and a marked increase in impervious surfaces. MSAVI-based functional classes indicate a shift from mixed low vegetation to predominantly sealed land, while tree canopy remained persistently low throughout redevelopment. The findings demonstrate measurable ecological simplification and canopy loss, even where nominal green areas remain present. By providing a rare multi-decadal, spatially explicit comparison of two contrasting planning paradigms within the same river corridor, the study contributes new empirical evidence on how governance and redevelopment models shape riparian ecological trajectories and sustainable urbanism in post-socialist cities. Strengthening blue-green infrastructure and restoring native riparian vegetation are essential for enhancing climate resilience and ensuring long-term riverfront sustainability. Full article

This study investigates how the initial oxygen fraction in a confined space affects post-vent combustion, gas composition, and pressure hazards during thermal runaway (TR) of 58 Ah prismatic Li(Ni_0.8Co_0.1Mn_0.1)O₂ lithium-ion cells. Thermal abuse experiments were conducted in a 250 L sealed chamber under five initial oxygen fractions (20%, 15%, 10%, 5%, and 0% O₂), with synchronized measurements of cell temperature, vent-jet temperature, chamber pressure, voltage, and post-event gas composition. A first-vent event occurred reproducibly at a cell surface temperature of approximately 155 °C, followed by TR onset at about 170 °C. Although the onset temperatures were only weakly affected by ambient oxygen concentration, the post-vent hazard escalation depended strongly on oxygen availability. As the initial oxygen fraction increased from 0% to 20%, the peak vent-jet temperature increased from 353 °C to 1172 °C, and the peak chamber pressure rose from 90.7 kPa to 523.1 kPa. Gas chromatography showed that H₂, CO₂, CO, CH₄, and C₂H₄ were the dominant gaseous products. Lower oxygen fractions promoted retention of combustible species, whereas higher oxygen fractions enhanced oxidation and increased the CO₂/CO ratio. An oxygen-participation parameter, η, was introduced to quantify the fraction of initially available chamber oxygen consumed during post-vent oxidation. The increase in η was positively associated with oxygen-involved heat release and chamber overpressure. When the accessible oxygen fraction was limited to 10% or below, secondary combustion and pressure buildup were markedly suppressed, although a localized near-field thermal hazard remained significant around 10% O₂. These results provide quantitative guidance for enclosure inerting, vent management, and post-vent hazard mitigation in high-energy lithium-ion battery systems. Full article

Background: Lumboperitoneal (LP) shunt surgery is an established treatment for idiopathic normal pressure hydrocephalus (iNPH). In Japan, patients undergoing LP shunt surgery are often hospitalized for several days to more than one week after surgery, even in uncomplicated cases, reflecting concerns regarding early complications, cerebrospinal fluid overdrainage, and discharge readiness in older adults. This study evaluated the feasibility and short-term safety of a perioperative optimization pathway for planned short-stay hospitalization after LP shunt surgery. Methods: This single-center retrospective before-and-after cohort study included 15 consecutive patients who underwent elective LP shunt surgery. Six patients were managed using a conventional hospitalization pathway, whereas nine patients were treated under a short-stay pathway targeting discharge after one postoperative night. Key perioperative modifications included a uniform higher initial programmable valve pressure (level 7), structured discharge education, scheduled postoperative analgesia, waterproof wound sealing permitting early showering, and early outpatient follow-up with head computed tomography for staged valve pressure adjustment. The primary outcome was 30-day safety, defined as readmission, reoperation, or major postoperative complications. Results: Baseline characteristics were generally comparable between groups, although the short-stay group was slightly older and had more frequent antithrombotic therapy. Mean hospital length of stay was shorter in the short-stay group than in the conventional group (3.7 ± 2.0 vs. 9.7 ± 0.8 days; median, 3 vs. 9.5 days). Orthostatic headache requiring valve adjustment occurred in three conventional cases but in none of the short-stay patients. No patients in the short-stay group required readmission or reoperation within 30 days. Conclusions: In this pilot before-and-after study, a short-stay LP shunt pathway incorporating perioperative optimization and individualized discharge decision-making was feasible and was not associated with an apparent increase in early adverse events. These findings should be interpreted as exploratory and may support further evaluation of short-stay management strategies for selected patients undergoing LP shunt surgery in Japan. Full article

The aim of this study was to evaluate setting time, hardness, solubility, bioactivity and interaction with dentin of four calcium silicate-based sealers (CSBS). Three single-phase CSBS (AH Plus Bioceramic/AHB, CeraSeal/CSL, TotalFill BC/TFL), one powder/liquid CSBS (BioRoot RCS/BRT) and an epoxy control (AH Plus Jet/AHP) were investigated. Setting time was evaluated on glass (G1) and dentin (G2) surfaces, by adding 1%wt purified water to single-phase products. For hardness measurements, the Shore-D hardness test was used. Solubility was assessed according to the ISO 6876:2012 standard. For bioactivity screening, 1-week set specimens were immersed in SBF or water (30 days/37 °C) and examined by ATR–FTIR spectroscopy. Interaction with dentin was tested by ATR–FTIR before and after contact with the sealers. For setting time in G1, all CSBS failed to comply with the ISO standard, while in G2, most materials were set in the range of 6–8 h, except for CSL. The ranking of significant differences in hardness was AHP, BRT > CSL, AHB, TFL. Regarding solubility, AHB, BRT and AHP were found to comply with the ISO standard, whereas CSL and TFL failed. For bioactivity, characteristic peaks of calcium phosphates were found in all CSBS, with TFL being the most bioactive. A chemical interaction between CSBS and dentin was registered, with a strong reduction in collagen peaks and an increase in carbonates. The CSBS tested exhibited great variance in their behaviour regarding the properties assessed, although a strong deproteinating effect was registered on dentin for all. Full article

In this paper, we present a system built on Hyperledger Fabric (HLF) that leverages Confidential Computing (CC) technologies to strengthen data privacy guarantees beyond those achievable through application-level mechanisms alone. While HLF natively supports data confidentiality through Private Collections (PCs), which restrict data visibility to a subset of authorized network participants, these mechanisms do not protect data at the hardware level: a privileged or compromised hosting platform can access plaintext data in memory and on the filesystem irrespective of HLF access control policies. To address this limitation, we integrate CC into HLF by adopting Intel Software Guard Extensions (SGX) in conjunction with the Gramine framework. This integration enables the execution of HLF components—peer nodes, orderers, Chaincodes and client applications—within Trusted Execution Environments (TEEs). Furthermore, to securely grant access to selected data to a trusted third-party software (TPS) external to the blockchain network, we leverage the Remote Attestation (RA) feature provided by CC, as streamlined by Gramine and enforced on a per-request basis, ensuring that only verified enclaves (or “SGX enclaves”) with expected measurements may access private data. In addition, the Sealing mechanism is employed to persistently store cryptographic material required by HLF components on the filesystem while preserving both confidentiality and integrity. Together, PCs, RA, Sealing, and enclave-based execution establish a layered privacy guarantee: PCs enforce application-level data segregation among channel participants; RA provides measurement-based access control for an external TPS; Sealing ensures that cryptographic material and blockchain state remain encrypted on the filesystem; and enclave-based execution protects data in use through hardware-level memory encryption. The proposed system has been applied and experimentally validated in a logistics use case in the Port of Genoa: benchmarks against an experimental HLF deployment demonstrate an average 95th-percentile (p95) performance overhead of approximately 1.3× attributable to SGX memory encryption and Gramine-based enclave execution, whereas an elevated memory usage footprint (33–35 GB per organization) has been measured, mainly due to the Gramine environment: this remains an open direction for future work. Full article

To improve the lubrication stability of centrifugal pump mechanical seals under high-speed and high-pressure conditions, a composite texture combining elliptical dimples and herringbone grooves is proposed. The Hybrid Groove–Ellipse (HGE) configuration aims to enhance hydrodynamic pressure generation and mitigate thermal accumulation within the sealing interface. A thermohydrodynamic (THD) lubrication model with cavitation was established, and the coupled governing equations were solved using the finite volume method over 600–6000 rpm and 0.1–1 MPa. The lubrication performance of circular, rectangular, and two elliptical textures was systematically evaluated to identify their hydrodynamic characteristics. The ellipse with major axis parallel to the flow direction exhibited the most favorable pressure distribution and load-carrying capacity. Based on this geometry, the HGE structure was developed. Compared with conventional herringbone grooves, the HGE texture increases local pressure buildup, improves the load-carrying-to-leakage ratio, and modifies cavitation distribution. The maximum interface temperature is reduced by approximately 10–20% under high-speed conditions, with improved temperature uniformity. These results demonstrate that geometric coupling can enhance both the hydrodynamic and thermal performance of mechanical seals. Full article

The proliferation of digital assets has catalyzed a profound decoupling between intangible property and traditional inheritance jurisprudence. Under the existing legal framework in Taiwan, practitioners must rely on the testamentary forms prescribed in Article 1189 of the Civil Code, which are fundamentally ill equipped to handle cryptographic assets. Specifically, Notarized Wills (Article 1191) necessitate full disclosure to a notary, creating a “Privacy–Security Paradox” where revealing private keys exposes assets to misappropriation. Conversely, while Sealed Wills (Article 1192) offer confidentiality, they are plagued by risks of physical degradation and technical non-executability. This study proposes zkWill, an EVM-compatible decentralized testamentary framework designed to bridge these structural gaps. By leveraging Zero-Knowledge Proofs (ZKPs), zkWill achieves a state of “blind compliance,” verifying that a sealed will meets the statutory requirements of the Civil Code without disclosing its underlying content. The system integrates the Permit2 protocol for secure asset migration and combines AES-256 encryption with IPFS to immunize testaments against centralized storage failures. Unlike conventional services that demand custodial trust, zkWill employs decentralized oracles to trigger automated execution, ensuring legacy distribution without compromising wallet private keys. Empirical data from the Arbitrum Sepolia testnet confirms that the framework maintains constant verification efficiency and a judicially resilient audit trail, providing a paradigm that harmonizes legal pragmatism with cryptographic security for digital inheritance. Full article

Terahertz time-domain spectroscopy (THz-TDS) has emerged as a powerful tool for probing hydrated materials and biological tissues, where water dynamics dominate the dielectric response. This study focuses on improving the methodology of THz-TDS by replacing conventional cuvettes, which introduce unwanted absorption, reflections, and liquid bubbles that must be accounted for during measurement interpretation, with nitrocellulose membranes of various pore sizes. The membranes were hydrated with deionized water and sealed with food-grade cling film, and their transmission properties were measured using THz-TDS. To interpret the measurements, transfer matrix method simulations were performed using the optical constants of water reported by some experimentalists, allowing verification of our data. The findings for deionized water highlight the reliability of the methodology. Our results demonstrate that nitrocellulose membranes provide stable and reproducible transmission measurements in good agreement with theoretical reference models, supported by weight retention studies and reproducibility tests conducted in spatial, temporal, and random measurement conditions. These improvements contribute to the development of more robust THz-TDS approaches for hydrated biological materials and suggest future applications in non-invasive tissue hydration monitoring and biomedical diagnostics. Full article

Water invasion has become a critical challenge during the late-stage development of gas reservoirs, particularly under harsh conditions characterized by high temperature, high salinity, and strong reservoir heterogeneity. Chemical water shutoff technologies have thus gained increasing attention as effective solutions for selectively restricting water production while preserving gas deliverability. This review systematically summarizes recent advances in chemical water shutoff for gas reservoirs, focusing on polymer gels, nanocomposite materials, relative permeability modification agents, and emerging functional fluids. The reviewed materials are analyzed in terms of dominant sealing mechanisms, gas–water selectivity, reservoir adaptability, and performance under extreme formation conditions. By critically comparing their advantages, limitations, and field applicability, key challenges related to deep placement, selective sealing, long-term stability, and engineering controllability are identified. To address these limitations, emerging concepts such as zonal synergistic water control and bioinspired gas–water barriers are discussed, integrating wettability regulation, multiscale sealing, and adaptive material responses. These strategies provide a conceptual framework and research direction for the design of next-generation, efficient, and sustainable chemical water shutoff systems in complex gas reservoirs. Full article

The service behavior of polyurea used for joint sealing and seepage control in concrete arch dams is governed by complex material, geometric, and interfacial nonlinearities. This study developed a generalized interface element model incorporating damage evolution based on the nonlinear Ogden constitutive theory of polyurea materials. Using the Xiaowan Arch Dam as the engineering case, a multiple-nonlinearity coupled numerical model was established, covering the construction period, impoundment period, and temperature cycles during the operation period. The mechanical responses of surface polyurea at different locations and under varying material parameters were systematically investigated. Results show that the proposed coupled model accurately captures nonlinear contact behavior. Governed by the structural stress pattern of the arch dam, the impermeable coating is predominantly subjected to compression, while regions of high tensile stress are confined to the bottom joint areas. In seepage-control design, the coating’s restraining effect on macroscopic dam deformation can be neglected; however, dam deformation must be treated as the primary boundary condition. It is recommended that polyurea with an elastic modulus of 50 MPa and a 3 mm thickness be adopted. Blindly increasing coating thickness or stiffness may instead significantly elevate the risk of internal tensile stress. Full article

Urban areas are increasingly exposed to water-related challenges, including flood risk and water scarcity, amplified by climate change, population growth, and extensive soil sealing. Addressing these pressures requires integrated stormwater management (SWM) strategies that balance hydraulic, environmental, and social objectives. This study introduces a novel, replicable Key Performance Indicator (KPI)-based assessment framework for 36 green–blue and grey sustainable stormwater management systems (SWMSs), designed to enable cross-typology, multiscale comparison. Six KPIs, encompassing flood regulation, water consumption, water quality, air quality, environmental amenity, and biodiversity potential, are derived through a critical synthesis and harmonisation of the literature and complemented with new parameters and sub-parameters to address existing methodological gaps. The framework structures evaluations into six analytical tables and one summary table, ensuring transparent, systematic, and comparative assessment of heterogeneous solutions. Application to a pilot project in Rome demonstrates how integrating KPI evaluation with parametric hydraulic modelling provides actionable insights for solution selection. It also facilitates identification of potential synergies between performance dimensions, enhancing its value as a decision-support tool in preliminary design. Overall, the study demonstrates the research value of multi-scalar, performance-based approaches for urban water planning, highlights the transferability of resilient stormwater strategies in climate-sensitive contexts, and identifies promising avenues for future research, including multi-sectoral integration, trade-off analysis, and cross-platform application. Full article

Conventional chemical gel plugging materials often suffer from poor high-temperature stability and inadequate mechanical properties. To address these issues, this study developed a high-performance composite gel material using a multi-component hybrid crosslinking strategy. The material employs γ-methacryloxypropyltrimethoxysilane (MPTMS) as the silica source, which hydrolyzes in situ to generate SiO₂, thereby enhancing temperature resistance. Laponite nanoplatelets are incorporated as a toughening agent and physical crosslinking points, while a self-synthesized reactive microgel (BWL) serves as the organic crosslinking core. Through copolymerization with monomers such as acrylamide (AM) and methacrylic acid (MAA), a triple-crosslinked network structure is constructed. Compared with conventional gels, the synthesized hybrid crosslinked composite gel maintains a high storage modulus and loss modulus after aging at 140 °C and exhibits excellent tensile and compressive properties. Furthermore, the gel was processed into particle-based lost circulation materials with different particle sizes. High-temperature and high-pressure plugging experiments demonstrate that when using a mixed system of 40–60 mesh, 20–40 mesh, and 10–20 mesh gel particles with a total concentration of 2%, it can effectively seal highly permeable sand beds and fractures with apertures up to 5 mm. This meets the engineering requirements for lost circulation materials with high strength and high stability in deep, high-temperature formations. Full article

The cement plug-casing interface is critical for long-term wellbore integrity in well abandonment to prevent fluid channeling. However, traditional cement easily debonds under long-term in situ stress and fluid exposure, causing seal failure and safety risks. To address this issue and overcome the limitations of conventional cement, a three-dimensional finite element model was established based on stress-seepage coupling theory. A systematic comparative analysis of the interface debonding mechanisms for three materials—cement, resin, and alloy—and their different combination sequences was conducted. The entire process of interface damage was quantified. The effects of material combination, formation elastic modulus, and injection rate on sealing performance were analyzed. Results show that the stiffness gradient dominates the failure mode, and the “cement–resin–alloy” configuration best suppresses damage propagation, reducing failure height by about 30%. Additionally, interface integrity is sensitive to formation constraints and operational parameters: the interface failure height decreases as the formation elastic modulus increases, and increases as the injection rate rises. The findings of this study can provide a theoretical basis and engineering reference for the optimal design of composite plugging barriers in demanding operational conditions, such as those encountered in carbon sequestration wells. Full article