Search Results (3,252)

The structural integrity of nuclear graphite is paramount for the lifespan of High-Temperature Gas-Cooled Reactors. The nuclear graphite components operate under extreme conditions involving high temperature, pressure, and intense neutron irradiation, leading to complex service behavior that is difficult to characterize only by experimental methods. This study employs the finite element method (FEM) to assess component stress and failure risk. The ManUMAT simulation method was first validated against irradiation data for Gilsocarbon graphite from an Advanced Gas-Cooled Reactor and was subsequently applied to stress–strain analysis of the nuclear graphite bricks in the HTR-PM side reflector layer. The 3D micropore structure of nuclear graphite was obtained via X-μCT and reconstructed in Avizo to establish an FEM model based on the actual pore geometry. Simulations of nuclear graphite over a 30 full-power-year service period predicted a significant contraction on the core-side and minimal thermal expansion on the out-side driven by the neutron doses. This research establishes a finite element framework that extends the ManUMAT approach by integrating a realistic pore structure model, thereby providing a foundation for quantifying the microstructural effects on macroscopic performance. Full article

This study evaluates energy conversion and heat transfer in a germicidal chamber employing gold nanorods (AuNRs) irradiated with an infrared laser (808 nm, 0.8 W) to generate heat via localized surface plasmon resonance. The investigation focused on the preliminary selection of chamber materials and the geometry of the bottom surface supporting the AuNRs as the heat source in a photothermoablation application. A one-way multiphysics and multiscale approach was applied, integrating nanoscale heating phenomena with a macroscale fluid and heat flow. The validated 2D numerical model shows satisfactory agreement with experimental data and is suitable for further design analyses. Computational Fluid Dynamics (CFD) simulations were conducted to determine temperature and entropy distributions, mean and maximum temperatures, and Nusselt numbers, allowing the assessment of the energy conversion process under different configurations and AuNR dimensions. The results indicate that a configuration with a gradually descending stepped structure enhances interactions between nanoparticles and the fluid, increasing the internal energy and producing elevated temperatures. Under optimal conditions, a temperature rise of approximately 75 °C was achieved. These findings demonstrate that integrating material selection, surface geometry, and nanoparticle absorbance optimization can significantly improve the efficiency of bacterial inactivation in germicidal chambers. This study provides a framework for future investigations on fully three-dimensional multiscale and multiphysical modeling, as well as a targeted AuNR design to maximize the thermal performance. Full article

The research and development of new accident-tolerant fuel cladding materials has emerged as a critical focus in international academic and engineering fields following the Fukushima nuclear accident. Due to the outstanding resistances in corrosion and radiation as well as high-temperature creep properties, oxide dispersion-strengthened (ODS) FeCrAl alloys have been studied extensively during the past decade. Current review articles in this field have primarily focused on the effects of chemical composition on the anti-corrosion performance and species of nano-oxide. However, several key issues have not been given adequate attention, including processing methods and parameters, high-temperature stability mechanisms, post-deformation microstructural evolution and high-temperature mechanical properties. This paper reviews the progress of basic research on ODS FeCrAl alloys, including preparation methods, the effects of preparation parameters, the thermal stability and irradiation stability of oxides, the microstructural deformation, and the mechanical properties at elevated temperatures. The aspects mentioned above not only provide valuable references for understanding the effects of preparation parameters on the microstructure and properties of ODS FeCrAl alloys but also offer a comprehensive framework for the subsequent optimization of ODS FeCrAl alloys for nuclear reactor applications. Full article

This study evaluates the influence of repeated processing, γ-irradiation (25 kGy), and additive formulation including Irgafos 168 (I168), Tinuvin 622 (T622), and Calcium Stearate (CaSt) on a polypropylene copolymer (PP-C). Motivated by medical technology applications, the study assessed effects on optical properties, yellowing, crystallization, mechanical performance, and viscosity using a full factorial design of experiments (DoE). Results showed γ-irradiation had the most significant impact, especially on zero-shear viscosity, which decreased by 84% after the first irradiation. The Yellowness Index (YI) changed measurably, but discoloration remained imperceptible. Crystallization temperature was influenced mainly by additive interactions, while specific enthalpy was affected by processing and γ-irradiation. Elongation at break and tensile strength were predominantly influenced by γ-irradiation, with elongation at break being a sensitive indicator of degradation. Zero-shear viscosity, correlating with molecular weight, was mainly controlled by γ-irradiation, indicating chain scission without critical embrittlement. Overall, γ-irradiation exerted a stronger effect than processing or additive formulation. Zero-shear viscosity proved a reliable measure of degradation, while elongation at break offered complementary insights. Despite significant viscosity reduction, mechanical properties remained high, confirming the material’s suitability for its intended applications. Full article

Assurance of the integrity of every weld joint is highly desirable, and defect detection methods that can be applied to welds at high temperatures immediately after welding are required. The laser ultrasonic (LU) method, which generates ultrasonic waves in the target via pulsed laser irradiation, is a well-known technique for non-contact defect detection during welding. Ultrasonic waves excited in ablation mode exhibit large amplitudes and predominantly surface-normal propagation, which has driven extensive research into their application for weld inspection. However, owing to the size and weight of conventional equipment, such systems have largely been limited to bench-top experimental setups. To address this, we developed an LU robotic system incorporating a compact, lightweight laser source and an improved signal-processing system. We conducted experiments to measure signals and to detect backside slits in flat plates and blowholes in lap-fillet welds. Additionally, a method to improve the sensitivity of laser interferometers was investigated and demonstrated on smut-covered areas near weld beads. Full article

This research involved functionalizing polypropylene (PP) films with 2-(Diethylamino)ethyl methacrylate (DEAEM), a monomer that responds to both temperature and pH. For this, Gamma-ray irradiation was used at a dose rate of 11.75 kGy h⁻¹, doses ranging from 30 to 100 kGy, and a monomer concentration of 50% (v/v). The modified films (PP-g-DEAEM) were characterized by thermal analysis, FTIR-ATR, swelling, and contact angle. Confirming that the films were successfully grafted with DEAEM, improving the wettability of the pristine PP films, with a critical pH of 5.6 and a temperature response at 45.7 °C. Subsequently, the films were subjected to ciprofloxacin loading and release, and their in vitro efficacy against the E. coli strain was assessed using the Kirby-Bauer method. This work suggests potential applications in biomedical devices; however, further studies are needed. Full article

This study investigates sustainable alternatives for thermal regulation in building materials by incorporating modified basic oxygen furnace slag (MBOFS) as a partial replacement for natural aggregates in concrete. MBOFS was produced by injecting oxygen and silica sand into molten BOF slag to reduce free CaO and MgO, enhancing stability and suitability for cementitious composites. Characterization revealed high mid-infrared emissivity (up to 95.92% in the 8–13 μm range), low solar reflectivity, and high absorptance—properties favorable for passive radiative cooling. Optical, physical, mechanical, and thermal evaluations included spectral analysis, tests for density, porosity, compressive strength, and indoor irradiation with heat flux and temperature monitoring. Increasing MBOFS content raised thermal resistance from 0.034 to 0.069 m²·K/W and lowered thermal transmittance from 3.644 to 3.235 W/m²·K. Higher heat storage capacity and higher emissivity (thermal radiation) suppress the thermal transmittance, thus improving the thermal resistance of the building walls. The 60% replacement showed the most balanced surface thermal response, whereas higher ratios yielded greater energy retention. These results demonstrate that MBOFS can enhance insulation, radiative cooling, and mechanical performance, advancing climate-responsive concrete for urban heat island mitigation. Full article

The 2025 International Technology Roadmap for Photovoltaics (ITRPV) projects that bifacial modules will dominate the photovoltaic (PV) market, reaching roughly 60–80% global share between 2024 and 2035, while monofacial PV modules will steadily decline. Current industry practice is to route the cable bundles along structural members such as main beams or torque tubes, thereby preventing rear-side shading but resulting in two key drawbacks: increased cable length and decreased system reliability due to cable proximity with rotating members and pinch points. Both effects contribute to higher system costs and reduced cable reliability. An alternative method involves suspending cable bundles directly behind the modules using hangers. While this approach mitigates excess length and risk of cable snags, it introduces the possibility of partial rear-side shading, which could possibly cause performance loss and hot-spot formation due to shade-induced electrical mismatch. Experimental evidence indicates that this risk is minimal, as albedo irradiance typically represents only 10–30% of front-side irradiance as reported in the literature and is largely diffuse, thereby limiting the likelihood of significant directional shading. This study evaluates the performance and reliability impacts of hanger-supported cable bundles under varying experimental conditions. Performance metrics assessed include maximum power output (Pmax), short-circuit current (Isc), open-circuit voltage (Voc), and fill factor (FF), while hot-spot risk was evaluated through measurements of module temperature uniformity using infrared imaging. Each cable (1X) was 6 AWG with a total outer diameter of approximately 9 mm. Experiments covered different cable bundle counts/sizes (2X, 6X, 16X), mounting configurations (fixed-tilt and single-axis tracker), and albedo conditions (snow-covered and snow-free ground). Measurements were conducted hourly on clear days between 8:00 and 16:00 from June to September 2025. The results consistently show that hanger-supported cable bundles have a negligible shading impact across all hours of the day and throughout the measurement period. This indicates that rear-side cable shading can be safely and practically disregarded in performance modeling and energy-yield assessments for the tested configurations, including fixed-tilt systems and single-axis trackers with or without torque tube shading and with various hanger sizes and cable-bundle counts. Therefore, hanging cables behind modules is a cost- and reliability-friendly, safe and recommended practice. Full article

This study presents the development and evaluation of multifunctional, thermoresponsive nanogels based on poly(N-vinylcaprolactam-co-N-vinylpyrrolidone) (P(NVCL-co-NVP)) with a poly(ethylene glycol) methyl ether methacrylate (PEGMA) shell and galactose (GAL) targeting ligand for colon cancer therapy. The nanogels were engineered to encapsulate two chemotherapeutic agents, curcumin (CUR) and 5-fluorouracil (5-FU), along with gold nanorods (GNRDs) to enable a synergistic chemo-photothermal treatment approach. These nanogels exhibit excellent biocompatibility and stability and a temperature-responsive drug release profile, leveraging the volume-phase transition temperature (VPTT) of the polymer network for controlled delivery. The inclusion of GNRDs permits efficient photothermal conversion upon near-infrared (NIR) irradiation, resulting in localized hyperthermia and, theoretically, improved cytotoxicity when combined with chemotherapeutics. In vitro studies on colon cancer cells demonstrated enhanced drug accumulation, photothermal ablation when the GNRD concentration was above a threshold, and superior antitumor efficacy of the CUR/5-FU-loaded systems. The effectiveness of the chemo/photothermal combination could not be demonstrated, possibly due to the low concentration of GNRD and/or the use of a single irradiation step only. This work highlights the potential of P(NVCL-co-NVP):PEGMA:GAL nanogels as versatile nanocarriers for combined chemo-photothermal therapy. A more effective chemo/photothermal combination for colon cancer treatment can be achieved through the optimization of the GNRD loading/irradiation dosage. Full article

This study investigates the influence of array height, irradiance, and wind speed on temperature difference and thermal gradients in photovoltaic (PV) arrays operating in hot, arid conditions. A field experiment was conducted in Mesa, Arizona (latitude 33° N), using two fixed-tilt PV module arrays installed at different elevations—one at 1 m and the other at 2 m above ground level. Each array comprised seven monocrystalline PV modules arranged in a single row with an 18° tilt angle optimized for summer performance. Data were collected between June and September 2025, and the analysis was restricted to 10:00–13:00 h to avoid shading and ensure uniform irradiance exposure on both arrays. Measurements included module backsheet temperatures at the center and edge modules, ambient temperature, plane-of-array (POA) irradiance, and wind speed. By maintaining identical orientation, tilt, and exposure conditions across all PV configurations, the influence of array height was isolated by comparing module operating temperatures between the 1-m and 2-m installations (inter-array comparison). Under the same controlled conditions, the setup also enabled an examination of how the intra-array comparison affects temperature gradients along the PV modules themselves, thereby revealing edge-center thermal non-uniformities. Results indicate that the 2 m array consistently operated 1–3 °C cooler than the 1 m array, confirming the positive impact of elevation on convective cooling. This reduction corresponds to a 0.4–0.9% improvement in module efficiency or power based on standard temperature coefficients of crystalline silicon modules. The 1 m array exhibited a mean edge–center intra-array temperature gradient of −1.54 °C, while the 2 m array showed −2.47 °C, indicating stronger edge cooling in the elevated configuration. The 1 m array displayed a broader temperature range (−7 °C to +3 °C) compared to the 2 m array (−5 °C to +2 °C), reflecting greater variability and weaker convective uniformity near ground level. The intra-array temperature gradient became more negative as irradiance increased, signifying intensified edge cooling under higher solar loading. Conversely, wind speed inversely affected ΔT, mitigating thermal gradients at higher airflow velocities. These findings highlight the importance of array height (inter-array), string length (intra-array), irradiance, and wind conditions in optimizing PV system thermal and electrical performance. Full article

Silver nanoparticles (AgNPs) are promising agents for nanomedicine but their interactions with lipid membranes, which are a key interfaces for drug delivery, require a deeper understanding. This study investigates the influence of fructose-capped AgNPs on the physicochemical properties of SOPC-based liposomal bilayers, with potential implications for drug delivery and photothermal therapy. We employed a multitechnique approach, including infrared (IR) spectroscopy, differential scanning calorimetry (DSC), thermally induced shape fluctuation analysis, and laser irradiation at 343, 515, and 1030 nm. Our results show that AgNPs incorporated into the bilayer cause measurable perturbations: DSC reveals a decrease in the main phase transition enthalpy (from 0.280 to 0.234 J/g) and temperature (from 2.80 to 3.41 °C), while shape fluctuation analysis indicates a reduction in bending modulus (from 1.18 × 10−19 J to 0.93 × 10−19 J), confirming increased membrane fluidity. FTIR confirms interactions of fructose-capped nanoparticles and the lipid’s carbonyl and phosphate groups. Furthermore, the AgNPs-liposomes exhibit a strong, wavelength-dependent photothermal response with a temperature increase of ≈22 °C under 515 nm laser irradiation, compared to only 3–5 °C at 1030 nm. We conclude that fructose-capped AgNPs moderately fluidify lipid bilayers while enabling efficient, controllable photothermal capability, making them excellent candidates for the eventual design of advanced liposomal systems for combined therapy and diagnostics. Full article

The effects of extreme heat events on Surface Urban Heat Island Intensity (SUHII) were investigated in Lecce (southern Italy) during the summer months (June–August) from 2018 to 2025. The analysis began with the identification of heatwave frequency, duration, and intensity using the Warm Spell Duration Index (WSDI), based on a homogenized long-term temperature record, which indicated a progressive increase in persistent extreme events in recent years. High-resolution ECOSTRESS land surface temperature (LST) data were then processed and combined with CORINE Land Cover (CLC) information to examine the thermal response of different urban fabrics, compact residential areas, continuous/discontinuous urban fabric, and industrial–commercial zones. SUHII was derived from each ECOSTRESS acquisition and evaluated across multiple diurnal intervals to assess temporal variability under both normal and WSDI conditions. The results show a consistent diurnal asymmetry: daytime SUHII becomes more negative during WSDI periods, reflecting enhanced rural warming under dry and highly irradiated conditions, despite overall higher absolute LST during heatwaves, whereas nighttime SUHII intensifies, particularly in dense urban areas where higher thermal inertia promotes persistent heat retention. Statistical analyses confirm significant differences between normal and extreme conditions across all classes and time intervals. These findings demonstrate that extreme heat events alter the urban–rural thermal contrast by amplifying nighttime heat accumulation and reinforcing daytime negative SUHII values. The integration of WSDI-derived heatwave characterization with multi-year ECOSTRESS observations highlights the increasing thermal vulnerability of compact urban environments under intensifying summer extremes. Full article

Reliable performance of TRISO (tristructural isotropic) nuclear fuel depends on the interplay between its multilayer architecture and the buffer-layer microstructure, which are difficult to isolate experimentally. We implement a multiscale, multiphysics model in the open-source MOOSE (Multiphysics Object-Oriented Simulation Environment) framework that couples particle-scale thermo-mechanical finite-element analysis with mesoscale phase-field fracture to link microstructure to effective stiffness and strength. The model resolves the combined influence of pore volume fraction, size, and aspect ratio and explicitly separates the effects of reduced load-bearing capacity from stress concentrations in the porous buffer. Simulations reveal substantial hoop stresses across coating layers under nominal thermal conditions due to material property mismatches and temperature gradients. In the buffer, stiffness and strength decrease with porosity; morphology is decisive: as aspect ratio decreases, strength degrades far more rapidly than stiffness, consistent with crack-like pores that amplify local stresses. The framework reproduces logarithmic trends with aspect ratio and explains the higher sensitivity of strength, providing parameters that can inform design and acceptance criteria (e.g., limits on pore elongation and porosity gradients). Implemented within MOOSE, the approach is readily extensible to irradiation-dependent kinetics, interface debonding, and uncertainty-quantified 3D analyses to support risk-informed TRISO fuel development. Full article

Both the CESM-simulated NNU-2K dataset and proxy reconstructions of Indian Summer Monsoon (ISM) precipitation over the past two millennia reveal a significant centennial-scale period, including periodicities of 105, 150, and 200 years. The 105- and 200-year cycles identified in the NNU-2K all-forcing (AF) experiment closely match those found in the volcanic single-forcing (Vol) experiment, suggesting that volcanic activity is a major driver of these variations. Volcanic forcing induces global cooling, which reduces the land–sea thermal contrast and weakens the monsoon circulation. Furthermore, stronger cooling in the Northern Hemisphere decreases the interhemispheric temperature gradient and weakens the trans-equatorial pressure gradient. This, in turn, suppresses cross-equatorial low-level flow from the Southern Hemisphere, further reducing ISM precipitation. The 105- and 150-year periodicities are also consistent with those in the total solar irradiance (TSI) single-forcing experiment, indicating a substantial response to solar variability. Increased solar irradiance enhances Northern Hemisphere warming, strengthening both the interhemispheric temperature gradient and the cross-equatorial pressure gradient. These changes facilitate stronger northward cross-equatorial flow in the lower troposphere, intensifying the ISM and increasing precipitation. Concurrently, solar forcing amplifies the thermal contrast between the Eurasian continent and the Indian Ocean, further reinforcing monsoon circulation. The 150-year cycle is also evident in the control (Ctrl) experiment, implicating internal climate variability as an additional mechanism. Analysis reveals a quasi-decadal Pacific Decadal Oscillation (PDO)-like sea surface temperature anomaly in the North Pacific. Its negative phase is linked to reduced sea-level pressure over the ISM region, enhanced low-level convergence, and increased precipitation. It also strengthens the Mascarene High over the Indian Ocean, intensifying the Somali Jet and southwesterly monsoon winds, which promote greater moisture transport into the ISM domain. Full article

In this paper, ultra-fast laser lift-off (LLO) of carbon nanotube (CNT)-integrated polyimide film (PI) was investigated by different laser burst mode and pulse intervals using the two-temperature model. By comparing the temperature field distributions of nanosecond, picosecond, and femtosecond lasers at different pulse intervals, it can be found that picosecond lasers cause a higher lattice temperature increase at the PI interface with specific pulse interval conditions. With the increase in the pulse interval, the lattice temperature of the three kinds of lasers decreased, indicating that the heat accumulation effect was weakened. In addition, under picosecond laser irradiation, the lattice temperature at the PI/glass interface of integrated CNTs could be significantly increased, which was significantly different from the system without integrated CNTs. The simulation results show that the picosecond laser is more suitable for LLO with an appropriate pulse interval, and the integration of CNTs at the PI/glass interface can effectively reduce the laser energy threshold required for the LLO process. Our work presents a new PI/CNT/glass model for ultra-fast laser low-threshold LLO and promotes the laser debonding technology in the fields of OLED and other optoelectronic chips. Full article