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The integration of a composite of porous medium with phase change material (PCM) offers significant advantages in thermal management systems, enhancing heat transfer efficiency and addressing various thermal regulation challenges. This approach utilizes the PCM's latent heat absorption and the enhanced thermal conductivity provided by the porous medium, resulting in optimized system performance. Its applicability spans across electronics cooling and building insulation systems. However, predicting the thermal behavior of this composite material is challenging, necessitating computational tools to anticipate its response under different conditions and evaluate its influence on cooling strategies. The objective of this study is to create a computational tool specifically tailored to evaluate constitutive parameters of this composite material, thereby providing a comprehensive description of its thermal behavior. To achieve this goal, the multiscale homogenization principle is employed to assess the composite's effective thermophysical material properties using the representative volume element approach. The repeating unit cell of the aluminum lattice is incorporated into the PCM to define a representative volume element. The finite element method (FEM) is utilized to solve the three-dimensional homogenization problem, yielding an orthotropic effective thermal conductivity due to the inherent symmetry of the repeating material cell. Moreover, the study leverages the apparent heat capacity method to effectively manage the phase transitions within the PCM domain, utilizing smooth and temperature-dependent functions to accurately describe the thermophysical properties of the PCM. Integrating the composite into battery pack thermal management, this study thoroughly examines thermal dynamics by comparing outcomes with and without PCM integration. The transient thermal problem is accurately tackled using the FEM, employing the evaluated effective constitutive parameters of the homogenized composite to minimize computational effort. The results indicate a notable decline in the highest temperatures of the battery pack, leading to a reduction of about 14 °C at the specific moment when the phase change material fully transitions into its liquid form. The obtained results emphasize the effectiveness and practical feasibility of the proposed thermal management strategy. The modeling approach presented provides a robust tool with significant efficiency in reducing computational time for analyzing the thermal behavior of large models, as the utilization of the homogenization technique notably decreases the computational time. [ABSTRACT FROM AUTHOR]

Using density functional theory, we study the preferential ordering of rod-like guest particles immersed in a smectic host fluid. Within a model of perfectly aligned rods and assuming that the guest particles do not perturb the smectic host fluid, simple excluded-volume arguments explain that guest particles that are comparable in length to the host particles order in phase with the smectic host density layering, whereas guest particles that are considerably shorter or longer order in antiphase. The corresponding free-energy minima are separated by energetic barriers on the order of the thermal energy kBT, suggesting that guest particles undergo hopping-type diffusion between adjacent smectic layers. Upon introducing a slight orientational mismatch between the guest particles and the perfectly aligned smectic host, an additional, smaller free-energy barrier emerges for a range of intermediate guest-to-host length ratios, which splits the free-energy minimum into two. Guest particles in this range occupy positions intermediate between in-phase ordering and in-antiphase ordering. Finally, we use Kramers' theory to identify slow, fast, and intermediate diffusive regimes for the guest particles as a function of their length. Our model is in qualitative agreement with experiment and simulation and provides an alternative, complementary explanation in terms of a free-energy landscape for the intermediate diffusive regime, which was previously hypothesized to result from temporary caging effects [M. Chiappini, E. Grelet, and M. Dijkstra, Phys. Rev. Lett. 124, 087801 (2020)]. We argue that our simple model of aligned rods captures the salient features of incommensurate-length guest particles in a smectic host if a slight orientational mismatch is introduced. [ABSTRACT FROM AUTHOR]

A simple low temperature and cost-effective hydrothermal method via reduction self-assembly and freeze-drying was fabricated to prepare graphene aerogel (rGO). After the reduction process, most of the oxygen-containing groups in graphene oxide have been removed by ascorbic acid. The surface C/O atomic ratio detected in rGO is about 7.26. The aerogel presents a nanoporous structure. This porous structure could act as a barrier to heat conduction. By heating the graphene aerogel and using infrared thermal imager to detect the temperature, the temperature difference between the top and the bottom of the aerogel reached 80 °C, which showed excellent thermal insulation performance. In addition, by testing the thermal imaging image of graphene aerogel placed on the skin surface, it exhibited an infrared stealth effect. This carbon aerogel may offer potential for the fabrication and application for thermal insulation and infrared stealth material systems. [ABSTRACT FROM AUTHOR]

C/C–HfC–SiC composites were prepared by reactive melt infiltration using Hf–Si alloy (Hf, more than 95 wt%) with a density of 3.86 g/cm3 and an open porosity of 8.34%. The microstructure, mechanical properties, and ablation behavior at high temperatures were studied in detail. SiC played a crucial role in alleviating the thermal mismatch between HfC and PyC, which formed at the interface between the carbon matrix and the HfC matrix. The flexural strength and modulus of C/C–HfC–SiC composites were 237 MPa and 37.6 GPa, respectively. The C/C–HfC–SiC composites exhibited excellent ablation resistance with a linear ablation rate of 8.9 × 10−3 mm/s and maintained a surface temperature above 2925°C during ablation. During this process, HfO₂ remained in a molten state with high viscosity and served as a thermal barrier, while the volatilization of SiO₂ effectively removed heat, protecting the composites from further ablation. [ABSTRACT FROM AUTHOR]

Expandable graphite (EG) is widely used in rigid polyurethane (PU) foam (RPUF) as flame retardant, however, the mechanical properties of RPUF would deteriorate with the increase of its content. To alleviate this problem, PU‐coated EG (PUEG) is prepared by coating PU on the surface of EG via interface polymerization. PUEG is characterized by FTIR, XPS, and SEM. The results show that PUEG is successfully prepared. Compared with the RPUF add with the pure EG, the compressive strength and flame retardancy of the RPUF prepared by adding 15% PUEG have been improved to varying degrees. A 15% PUEG and 20% PUEG modify RPUFs obtained both UL‐94 V‐0 rating with LOI values of 29.7% and 31.2%, respectively. The improvement in the flame retardancy and compressive strength of RPUF is due to the good interfacial compatibility between the RPUF and PU on the surface of the EG and the increased coking rate of the EG, which accelerates the formation of the thermal barrier carbon layer. The preparation process of PUEG is simple and suitable for large‐scale production. [ABSTRACT FROM AUTHOR]

The whole (or holistic) building design approach is important for sustainability and fire safety. It is, however, challenging to design a building holistically due to it requiring a designer to take into account various design factors and their effects on multiple performances. It is very difficult to do such a design without a proper design tool. This study proposes a performance-based, multi-characteristic optimization tool for a wall-insulation system. The wall-insulation system of a building has multiple performance objectives, such as energy-saving, fire safety, soundproofing, sustainability, and cost. The tool quantifies the performance values of the five objectives and identifies the best combination of sheathing layers and insulation materials based on the quantified performance value. This tool also addresses an issue of the current insulation system design approach in the building code, by proposing a performance-based design approach for a thermal barrier design. The tool is expected to assist architects or building designers in comparing various wall-insulation systems. [ABSTRACT FROM AUTHOR]

This study addresses the need for bio-fuels as alternatives to fossil fuels in diesel engines, focusing on Nannochloropsis Algae bio-fuel. It aimed to explore the effects of adding tin oxide nanoparticles to the bio-fuel and applying Lanthanum Zirconate coatings to engine parts. The research tested four fuel types: pure diesel, pure Nannochloropsis Algae, 80% diesel + 20% Nannochloropsis Algae, and 80% diesel + 20% Nannochloropsis Algae + tin oxide. Fuel properties like density, calorific value, viscosity, Cetane number and flash point were determined. The engine's performance was evaluated by measuring brake specific fuel consumption, brake thermal efficiency, emissions, heat release rate, and peak pressure. Results showed that the fuel blend of 80% diesel + 20% Nannochloropsis Algae + tin oxide in a coated engine had 5.7% lower brake specific fuel consumption and 9.2% higher brake thermal efficiency compared to diesel. Emissions of carbon monoxide, hydrocarbons, and smoke were reduced by 18.8%, 21.8%, and 17% respectively. The Lanthanum Zirconate coating alone decreased brake specific fuel consumption by 2.8% and increased brake thermal efficiency by 4.1%, with emissions reductions of 18%, 20%, and 16% respectively. This study highlights the potential benefits of bio-fuel blends and advanced coatings in diesel engines. [ABSTRACT FROM AUTHOR]

We tested whether older adults, compared with young adults, exhibit greater gastrointestinal permeability and kidney injury during heat stress. Nine young (32 ± 3 years) and nine older (72 ± 3 years) participants were heated using a model of controlled hyperthermia (increasing core temperature by 2°C via a water‐perfused suit). Gastrointestinal permeability was assessed using a multi‐sugar drink test containing lactulose, sucrose and rhamnose. Blood and urine samples were assayed for markers of intestinal barrier injury [plasma intestinal fatty acid binding protein (I‐FABP), plasma lipopolysaccharide binding protein (LBP) and plasma soluble cluster of differentiation 14 (sCD14)], inflammation (serum cytokines), kidney function (plasma creatinine and cystatin C) and kidney injury [urine arithmetic product of IGFBP7 and TIMP‐2 (TIMP‐2 × IGFBP7), neutrophil gelatinase‐associated lipocalin and kidney injury molecule‐1]. The lactulose‐to‐rhamnose ratio was increased in both young and older adults (group‐wide: Δ0.11 ± 0.11), but the excretion of sucrose was increased only in older adults (Δ1.7 ± 1.5). Young and older adults showed similar increases in plasma LBP (group‐wide: Δ0.65 ± 0.89 µg/mL), but no changes were observed for I‐FABP or sCD14. Heat stress caused similar increases in plasma creatinine (group‐wide: Δ0.08 ± 0.07 mg/dL), cystatin C (group‐wide: Δ0.16 ± 0.18 mg/L) and urinary IGFBP7 × TIMP‐2 [group‐wide: Δ0.64 ± 0.95 (pg/min)2] in young and older adults. Thus, the level of heat stress used herein caused modest increases in gastrointestinal permeability, resulting in a mild inflammatory response in young and older adults. Furthermore, our data indicate that older adults might be more at risk for increases in gastroduodenal permeability, as evidenced by the larger increases in sucrose excretion in response to heat stress. Finally, our findings show that heat stress impairs kidney function and elevates markers of kidney injury; however, these responses are not modulated by age. What is the central question of this study?Do older adults exhibit greater gastrointestinal permeability and heightened kidney injury risk during heat stress than young adults?What is the main finding and its importance?Hyperthermia increased gastrointestinal permeability, resulting in a mild inflammatory response in both young and older adults. However, older adults might be more at risk for increases in gastroduodenal permeability in response to heat stress. In addition, we show that heat stress impairs kidney function and elevates markers of kidney injury; however, these responses are not modulated by age during controlled hyperthermia. These findings serve as an important step towards improving our understanding of the risk factors that might contribute to heat‐related morbidity/mortality. [ABSTRACT FROM AUTHOR]

Background: High-temperature environment can cause acute kidney injury affecting renal filtration function. To study the mechanism of renal injury caused by heat stress through activates TLR4/NF-κB/NLRP3 signaling pathway by disrupting the filtration barrier in broiler chickens. The temperature of broilers in the TN group was maintained at 23 ± 1 °C, and the HS group temperature was maintained at 35 ± 1℃ from the age of 21 days, and the high temperature was 10 h per day, and one broiler from each replicate group at the age of 35 and 42 days was selected for blood sampling, respectively. Results: The ELISA results demonstrated that in comparison to the TN group, serum CORT content of broilers in the HS group was all remarkably elevated (P < 0.01); the levels of IL-6 and TNF-α in the serum were remarkably elevated (P < 0.05 or P < 0.01); serum CAT and SOD activities were all remarkably reduced (P < 0.05 or P < 0.01), and serum LDH activity and MDA content were all remarkably decreased (P < 0.05); serum BUN and CRE levels were remarkably elevated (P < 0.01). Pathological sections and transmission electron microscopy demonstrated that the structure of the renal filtration barrier in the HS group damaged gradually with the prolongation of heat stress in comparison to the TN group, but the damage was reduced at 42 days of age; the levels of TLR4, MyD88, NF-κB, NF-κB-p65, NLRP3, caspase-1 and IL-1β mRNAs were all up-regulated (P < 0.05 or P < 0.01) in renal tissues of the HS group, indicating that heat stress caused damage to the morphological structure and function of the renal filtration barrier and that TLR4/NF-κB/NLRP3 pathway was also affected by heat stress, leading to increased activity (P < 0.05 or P < 0.01). Conclusions: It demonstrated that heat stress caused detrimental effects on both the morphological structure and function of the renal filtration barrier, and the initiation of the TLR4/NF-κB/NLRP3 signaling pathway exacerbated the inflammatory damage, leading to increased thermal damage to renal tissues and glomerular filtration barriers; however, with the prolongation of heat stress, broilers gradually developed heat tolerance, and the damage to the renal tissues and filtration barriers triggered by heat stress was mitigated. [ABSTRACT FROM AUTHOR]

Stress relaxation is key to the ultrahigh strength valve springs but has received little attention. In this work, three 55SiCr spring steels with an identical tensile strength of 2000 MPa are prepared by tailoring the wire speed in an industrial production line. The high wire speed results in the presence of undissolved Fe3C carbides and the formation of dislocation martensite in S1 steel with fine prior austenite grains, while the low wire speed and sufficient austenitization time result in the formation of carbide‐free twinned martensite in S3 steel with coarse prior austenite grain. Relaxation experiment in 373 and 473 K demonstrates that the S3 steel has the lowest stress relaxation rate among the three steels. It demonstrates that the carbide‐free twin martensite has the best stress relaxation resistance due to its strong barrier against the thermal activation activities of dislocations. [ABSTRACT FROM AUTHOR]

The types of solid fires are diverse and the suppression highly depends on the adhesion and surface cooling effects of the extinguishing agent. In order to overcome the disadvantage of low adhesion and improve the efficiency of water in suppressing fires, a novel environmental-friendly thermal gelation hydrogel was prepared with hydroxypropyl methylcellulose (HPMC), sodium n-dodecyl sulfate (SDS), and super absorption resin (SAR) as the main raw materials. Ammonium polyphosphate (APP) and aluminum hydroxide (ATH) were added to enhance the fire-suppressive properties of the hydrogel. Then, cone calorimetry experiments were carried out to investigate the suppression effects differences between the hydrogels and water. According to response surface methodology, the optimal composition of hydrogel is the amount of HPMC, SDS, and SAR was 1.28 wt%, 1.50 mM, and 0.20 wt%, respectively. By adding APP and ATH flame retardants in combination, the hydrogel exhibited a reduced gelation temperature and an improvement in viscoelasticity, making it more effective in suppressing fires. Compared with water, solid fuel samples covered with hydrogel presented longer time to ignition. The maximum heat release rate was reduced by 53.27 kW/m2 and total smoke production exhibited a reduction of 12.23%. The hydrogel generated a fireproof and dense char layer on the solid surface, which acted as a barrier against heat and mass exchange, effectively suppressing the development of fire. The results of this study can provide guidance for the development of hydrogel extinguishing agents. [ABSTRACT FROM AUTHOR]

This article describes an innovative thermal insulation barrier in the form of a sandwich panel manufactured using 3D FDM printing technology. The internal structure (core structure) of the barrier is based on the Kelvin foam model. This paper presents the influence of the parameters (the height h and the porosity P of a single core cell) of the barrier on its properties (thermal conductivity, thermal resistance, compressive strength, and quasi-static indentation strength). The dominant influence of the porosity of the structure on the determined physical properties of the fabricated samples was demonstrated. The best insulation results were obtained for single-layer composites with a cell height of 4 mm and a porosity of 90%, where the thermal conductivity coefficient was 0.038 W/(m·K) and the thermal resistance 0.537 (m2·K)/W. In contrast, the best compressive strength properties were obtained for the 50% porosity samples and amounted to about 350 MPa, while the moduli for the 90% porosity samples were 14 times lower and amounted to about 26 MPa. The porosity (P) of the composite structure also had a significant effect on the punch shear strength of the samples produced, and the values obtained for the 90% porosity samples did not exceed 1 MPa. In conclusion, the test showed that the resulting 3D cellular composites offer an innovative and environmentally friendly approach to thermal insulation. [ABSTRACT FROM AUTHOR]

This article presents the development of a resistive frost-detection sensor fabricated using Fused Filament Fabrication (FFF) with a conductive filament. This sensor was designed to enhance demand-defrost control in industrial refrigeration systems. Frost accumulation on evaporator surfaces blocks airflow and creates a thermal insulating barrier that reduces heat exchange efficiency, increasing energy consumption and operational costs. Traditional timed defrosting control methods can mitigate these effects but often lead to inefficiencies due to their inability to align with actual frost accumulation, which can vary according to system and environmental conditions. Frost-detection sensors aim to solve this problem by acting as a tool to support defrosting control. A series of tests were conducted to evaluate the sensor's performance in detecting frost under controlled conditions on a heat exchanger (HX). The sensor reliably detected frost in all cases, demonstrating its effectiveness in real-time frost detection. The sensor measurements were validated by comparison with results obtained through a computer vision method, confirming its reliability. It was also found that the sensor can detect temperature changes. This advancement in sensor technology highlights the potential of additive manufacturing to provide cost-effective, customizable, replicable, and compact sensor designs, contributing to improved system performance and energy efficiency in refrigeration systems. [ABSTRACT FROM AUTHOR]

Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) is a biodegradable biopolymer from the PHAs family that has potential to replace conventional plastics and reduce plastic pollution. However, PHBV has thermo-sealability issues, making it challenging to use for bags. Blending it with polycaprolactone (PCL) could address this but may alter the barrier properties of the films, affecting their effectiveness as food packaging material. This study examined the properties and heat-sealing capacity of PHBV/PCL blend films (ratios: 60/40, 50/50, and 40/60), obtained by melt blending and compression moulding. Both polymers are immiscible and were in separated phases; the continuous phase was PHBV in the 60/40 blend and PCL in the 40/60 blend, while the 50/50 sample exhibited interpenetrating bicontinuous phases of both polymers. The permeability to water vapour, oxygen, and D-limonene increased as the PCL content rose, especially when it formed the continuous phase in the matrix. The elastic modulus and resistance to break decreased, while extensibility increased, more markedly when PCL was the continuous phase. However, the continuity of PCL phase provided the films with better thermal adhesion and seal strength. The 50/50 blend showed the best balance between heat sealability and barrier properties, making it the most suitable for food packaging in sealed bags. [ABSTRACT FROM AUTHOR]

The development of hypersonic unmanned aerial vehicles (UAVs) for aerospace systems presents ambitious challenges for scientists and engineers. Extreme flight conditions, such as ultra-high speeds and significant aerodynamic heating, necessitate the creation of new materials capable of withstanding such loads. One of the most promising materials for constructing hypersonic UAVs is carbon fiber-reinforced polymer based on bisphenol nitrile. This material exhibits high thermal resistance, chemical stability, and excellent mechanical properties. Utilizing bisphenol nitrile combined with carbon fibers has enabled the production of composite materials that can operate at temperatures exceeding 3000C, far surpassing the capabilities of traditional polymer matrices. To assess the suitability of the developed carbon fiber-reinforced plastic for hypersonic UAV applications, comprehensive studies of its physical, mechanical, and thermal characteristics were conducted across a wide temperature range from 20 to 3000C. The obtained results provided a detailed characterization of the composite and allowed for comparisons with other high-temperature composite materials. The developed carbon fibre-reinforced plastic based on bisphenol nitrile binder shows great promise for constructing hypersonic UAVs. Its high thermal resistance, combined with excellent mechanical properties, makes it suitable for use in the extreme temperature conditions typical of hypersonic flight. [ABSTRACT FROM AUTHOR]

We report here the synthesis of a series of nine coordinated mononuclear LnIII complexes [LnL1Cl2(DMF)]Cl·2.5DMF and [LnL1(L2)2]Cl·4CH3OH (LnIII = GdIII, DyIII, ErIII and YbIII, HL2 = 9-anthracenecarboxylic acid), where L1 is a hexadentate N4O2 Schiff base ligand prepared from the condensation of 1,10-phenanthroline-2,9-dicarbaldehyde and semicarbazone. The X-ray crystal structures of these complexes show the LnIII ions to possess LnN4O2Cl2 and LnN4O4 coordination spheres, which can be considered to be derived from a hexagonal bipyramidal geometry, with the ligand in the equatorial plane and the anions (chloride or 9-antracenecarboxylate) in axial positions, which undergo distortion after coordination of either a molecule of DMF or a bidentate coordination of the 9-anthracenecarboxxylate ligand. All these compounds exhibit field-induced slow magnetization relaxation (SMR). The absence of SMR at zero field due to QTM, as well as the processes involved in the magnetic relaxation under a field of 0.1 T, have been justified on the basis of theoretical calculations and the distortion of the respective coordination spheres. The severe discrepancy between the calculated and experimental thermal energy barriers for the DyIII complexes seems to indicate that the relaxation occurs with the contribution of spin–vibrational coupling, which is favored by the flexibility of the ligand. [ABSTRACT FROM AUTHOR]

Influenced by the local angle of attack of the air rudder, a complex separation and reattachment flow will form at the position of the full-motion rudder shaft thermal-protection ring during a hypersonic flight, accompanied by severe aerodynamic heating loads, which is the weak link in the thermal protection design of the air rudder. Taking the flat plate/air rudder shaft thermal-protection ring as the research object, the numerical calculation method was used to study the influence rule of different rudder deflection angles and geometric parameters of the thermal-protection ring′s annular gap on the flow and aerodynamic heating. The numerical calculation was based on the unstructured hybird gird finite volume method. The calculation results and analysis show that the rudder deflection has the greatest effect on the heat flux distribution in the thermal-protection ring. Under the condition of rudder deflection, a reattached flow and high flux region will form at the chamfer of the thermal-protection ring. The area of the high flux region and the flux peak are proportional to the rudder deflection angle. When the rudder deflection angle equals 0°, the airflow at the Z=0 mm cross-section of the annular gap will flow upward into the gap at the bottom of the rudder surface. When the rudder deflection angle is greater than 0°, the incoming flow in the gap at the bottom of the rudder surface will form a vortex in front of the chamfer of the thermal-protection ring, and at the same time the airflow on the flat plate enters the annular gap downward and forms a vortex in the direction of the gap depth. When the rudder deflection angle and the gap width are fixed, the gap depth mainly affects the heat flux at the chamfer of the thermal-protection ring and the annular gap windward side. As the gap depth increases, the flow structure at the Z=0 mm cross-section of the annular gap develps from 2 vortices to 3 vortices. When the rudder deflection angle and the gap depth are fixed, the gap width mainly affects the heat flux at the annular gap windward side. As the gap width increases, the vortex at the Z=0 mm cross-section of the annular gap develops more fully, and the flow structure in the depth direction develops from 3 vortices to 2 main vortices and 2 small vortices at the bottom of the annual gap.

The gas injection effect is the main heat dissipation mechanism of ablative materials, which would significantly affect the thermal insulation characteristics of ablative thermal protection systems. Based on the shock tube wind tunnel, the experimental study on the influence of gas injection on downstream aero-heating was conducted. The influence of factors such as gas injection, mainstream Mach number, Reynolds number was obtained. Combined with numerical simulation results, the correlations of the influence of gas injection on aero-heating were obtained under laminar and turbulent boundary layer flow conditions. The cooling efficiency of gas injection for laminar boundary layer is remarkable. The maximum cooling efficiency for laminar boundary layer is close to 100% when the blowing ratio F=0.483%. The cooling efficiency would decrease sharply when the boundary layer transition occurs because of the strong mixing effect of turbulent boundary layer. The larger the specific heat capacity of cooling gas, the better the cooling effect.

Lower Critical Solution Temperature (LCST) of macromolecular systems is important in thermoresponsive smart window design. However, controlling the LCST behavior and sustaining the shelf‐life are challenging tasks. Herein, how photochemistry can be tweaked to design sustainable smart windows that allow controlled transmission of solar radiation is described. The cyanostilbene substituted naphthalenes 1(Z) and 2(Z), show Z/E‐photoisomerization and subsequent Mallory cyclization resulting in significant modulation in clouding temperatures (Tcloud). At 1 mM concentration, the Tcloud of 1(Z), and 1(E) are 33 ± 0.1 and 28 ± 0.13 °C, respectively whereas 2(Z) and 2(E) exhibit Tcloud around 37 ± 0.1 and 30 ± 0.1 °C, respectively. The high thermal barrier for the E/Z back isomerization of 1(E) and 2(E) and removal of oxygen from the reaction medium allow control of the photoprocesses, thereby facilitating the construction of sustainable smart windows that respond to the surrounding temperature. A 30 × 30 cm2 window prototype containing an aqueous solution of 1(Z) (1 mM) exhibits a fully transmissive state at 25 °C and a nearly zero‐transmissive state at 33 °C for 10,000 cycles of operation. [ABSTRACT FROM AUTHOR]

Large‐size MXene flakes have drawn growing attention due to their fascinating properties, which inevitably suffer from the low yield and weak oxidation resistance. Herein, an electrochemical exfoliation approach is proposed to achieve a high recording yield of 87% for preparing large antioxidative MXene flakes with an average lateral size of 8.3 µm, which combines the etching, electrolyte intercalation, interlay expansion, and short‐time sonication. Moreover, the MXene flakes can keep stable for over three months in the presence of water and oxygen, and even have good stability over 500 °C under an air atmosphere, ascribed to the protection of the surface electrolyte layer. Combined with bacterial cellulose, the MXene can serve as an intelligent resistance‐type sensor for contact/non‐contact fire alarm, and further integrate with IoT for remote fire detection and warning within 1 s. In addition, the MXene significantly improves the flame‐retardant properties of indoor textiles and household materials, owing to the large thermostable 2D barriers to restrain heat and mass transfer. This work establishes an innovative and efficient method to prepare the large antioxidative MXene flakes in high yield for practical usage and extends its application to polymeric fire safety. [ABSTRACT FROM AUTHOR]

This research intends to create biodegradable packaging films using solution casting method. The films are composed of guar gum, carboxymethylcellulose, and blends of these materials with citric acid as a crosslinking agent. The concentration of citric acid ranges from 10 to 30% (w w−1). This study performs a curing treatment at 140°C for 30 min on the dried films containing the crosslinking additive to promote the esterification between the polymeric matrix and the crosslinking agent. The thin films have a smooth, homogeneous, and transparent aspect. Although the crosslinking reaction – evidenced by FTIR spectra – does not affect the thickness of the material, it causes a slight color variation making the samples assume a yellowish shade. Moreover, the crosslinking process enhances the water resistance, decreases the crystallinity index, and improves the water vapor barrier and thermal resistance of the films. The SEM images reveal the excess of unreacted crosslinking agent accumulated on the samples; these particles work as a plasticizer, affecting the morphology of the films as well as their water resistance, crystallinity, and thermal resistance. [ABSTRACT FROM AUTHOR]

Knowing the structure of the crust is critical to understanding a planet's geologic evolution. Crustal thickness inversions rely on bulk density estimates, which are primarily affected by porosity. Due to the absence of high‐resolution gravity data, Mercury's crustal porosity has remained unknown. Here, we use a model that was calibrated to the Moon to relate Mercury's impact crater population and long‐wavelength crustal porosity in the cratered terrains. Therein, porosity is created by large impacts and then decreased as the surface ages due to pore compaction by smaller impacts and overburden pressure. Our models fit independent gravity‐derived porosity estimates in the northern regions, where data is well resolved. Porosity in the cratered terrains is found to be 9%–18% with an average and standard deviation of 13% ± $\pm $ 2%, indicating lunar‐like crustal bulk densities of 2,565 ± $\pm $ 70 kg m−3 ${\mathrm{m}}^{-3}$ from which updated crustal thickness maps are constructed. Plain Language Summary: The crust of a planet is a thermal barrier, which controls how fast heat escapes to space. Depending on its thickness, the crust can strongly insulate the planet's interior preventing efficient cooling. Therefore, knowing the structure of the crust is critical to unraveling the geologic history of planetary bodies. Crustal thickness is typically inverted from gravity and topography data. One critical parameter for these inversions is the bulk density of the crust, which is primarily driven by porosity variations. While high‐resolution gravity field mapping allowed constraining the bulk density and porosity of the lunar crust, crustal porosity on other planetary bodies has remained unknown. In this work, we use a model that was calibrated to the Moon to relate Mercury's impact crater population and long‐wavelength crustal porosity in the cratered terrains. We show that crustal porosity in the cratered terrains ranges from 9% to 18% with an average and standard deviation of 13% ± $\pm $ 2%, indicating lunar‐like low bulk densities of 2,565 ± $\pm $ 70 kg m−3 ${\mathrm{m}}^{-3}$. Key Points: Mercury's crustal porosity estimated from the crater population, assuming porosity formed by large impacts and decreased with surface agingCrustal porosity in the cratered terrains ranges from 9% to 18% with an average and standard deviation of 13% ± 2%The low bulk density of Mercury's crust in the cratered terrain, 2,565 ± 70 kg m−3, is similar to that of the lunar highlands [ABSTRACT FROM AUTHOR]

In hypersonic flight the shock wave and turbulent boundary layer interaction (STBLI) sharply increases wall heat transfer that intensifies the aerodynamic heating problems. In this work the STBLI is modelled by compression ramp flow with a Mach number of 5, a Reynolds number based on momentum thickness of 4652 and a wall to recovery temperature ratio of 0.5. The aerodynamic heat generation and transport mechanisms are investigated in the interaction based on theoretical analysis and direct numerical simulation (DNS) that agrees with previous studies. A prediction correlation of wall heat flux in STBLI is deduced theoretically and validated by some representative data including the present DNS, which improves the prediction accuracy and can be applied to a wider $Ma$ range compared with the canonical Q-P theory. The correlation indicates that the sharp increase of wall heat transfer in the STBLI can be explained by the boundary layer compression and the convection transport enhancement. Based on the DNS results, the aerodynamic heat generation and transport mechanisms are revealed in the separation, recirculation and reattachment zones in the STBLI. From this perspective, the peak heat flux can be further explained by the enhancement of near-wall turbulent energy dissipation, compression aerodynamic heat generation and the near-wall turbulent transport. The generation and transport of compression aerodynamic heat reveal the underlying mechanism of the strong correlation between the peak heat flux ratios and the pressure ratios in STBLIs. [ABSTRACT FROM AUTHOR]

The performance of plasma sprayed thermal barrier coatings (TBCs) is strongly dependent on the quality of the feedstock powders, which usually are fabricated by conventional spray drying and multi-step sintering methods. In this work, a novel supersonic plasma spheroidization technology was employed to fabricate the spherical nanocrystalline Sc 2 O 3 -Y 2 O 3 co-stabilized ZrO 2 (ScYSZ) powder. The deformation process from the irregular powder to the spherical one was stimulated by the COMSOL phase field simulation. The results suggested that the original irregular pyrolysis products of ScYSZ precursors were aggregated into spherical powders by plasma spheroidization technology. The COMSOL simulations verified that the powder changed from irregular particles to spherical ones. The spheroidized ScYSZ particles exclusively consisted of non-transformed t' -ZrO 2 phase and showed good fluidity, smooth surface and high apparent density, which were expected to have a broader application prospect in the field of TBCs and other ceramic coatings. [ABSTRACT FROM AUTHOR]

Magnetohydrodynamic flow control is an active thermal protection method for atmospheric entry vehicles. This study examined the plasma characteristics under magnetohydrodynamic flow control and its thermal protection ability at multiple altitudes (20-60 km) on a typical direct Mars entry path using numerical simulation considering the Hall effect. The simulation considered a spherical-conical capsule with an entry velocity of 8 km/s at an altitude of 60 km, equipped with a dipole magnet generating a magnetic field of approximately 0.3 T at the stagnation point of the capsule. The results showed that magnetohydrodynamic flow control can mitigate convective aerodynamic heating at high altitudes (45 km or more), where the high electrical conductivity of the plasma creates strong magnetohydrodynamic interaction. In contrast, at low altitudes (35 km or less), magnetohydrodynamic flow control is ineffective owing to low electrical conductivity. The high electrical conductivity at high altitudes is attributed not only to large flight velocities under low atmospheric pressures but also to the enlargement of the shock layer owing to the strong magnetohydrodynamic interaction, which expands the ionization progression area. Furthermore, the results indicated that considering the Hall effect in the numerical modeling of magnetohydrodynamic flow control in Mars direct entry is essential. [ABSTRACT FROM AUTHOR]

Introduction: The objective of this experiment was to investigate the thermal effects on hyaluronic acid fillers, PCL fillers, and PDO threads when exposed to controlled heat. This study aims to provide insights into how these materials respond to thermal energy, which is crucial for safe and effective cosmetic procedures involving combined modalities. Materials and Methods: Cadaveric tissue was utilized to simulate clinical conditions. Hyaluronic acid fillers were injected at approximately 1 mm and 5 mm thicknesses, with variations in G' value (high and low). PCL fillers were similarly injected in 1 mm and 5 mm thicknesses. PDO threads were also inserted. All materials were injected at a depth of 2 cm. A thermometer was used to measure heat penetration, and a multi‐wavelength laser was applied to the tissue. The temperature was maintained at 60°C for 5 min to assess whether heat penetrated more than 3 cm in thickness. Observations were made regarding the heat distribution and any physical changes in the fillers and threads. Results: In thick layers, heat accumulated above the PCL filler without penetrating deeper layers. In thin layers, heat penetration was observed. For the HA fillers, heat energy was not blocked, regardless of the G' value or thickness. For the threads, no significant heat blockage effect was observed. For all materials, no visual changes were detected in any of the materials due to temperature exposure. Discussion: The findings suggest that the thickness and composition of fillers significantly influence heat penetration. Thick PCL fillers act as a thermal barrier, whereas thin PCL fillers allow deeper heat penetration. Hyaluronic acid fillers do not impede heat transfer, regardless of their physical properties. PDO threads do not exhibit any notable thermal resistance. These insights are essential for optimizing the safety and efficacy of combined filler and energy‐based device treatments in esthetic medicine. [ABSTRACT FROM AUTHOR]

Segmented thermoelectric (TE) legs are promising for improving heat‐electricity conversion efficiency, but their practical applications are still limited by the lack of cost‐effective interface‐connection technology. Here, an interface‐connection method for one‐step sintering of GeTe‐Bi2Te3 segmented TE legs is developed using mixtures of Al0.88Si0.12 and Ni (ASN) as diffusion barrier materials. Although the interface‐connection performance using Ni or Al0.88Si0.12 alone is poor, their mixtures can realize a compromise optimization of interface‐connection properties, simultaneously achieving a matched coefficient of thermal expansion, low contact resistivity, high shear strength, and high reliability. These robust interface‐connection properties can be attributed to the activation of the eutectic‐alloy Al0.88Si0.12 and the formation of appropriate reaction‐diffusion layers between ASN and GeTe/Bi2Te3 and between Al0.88Si0.12 and Ni in ASN. Finally, a remarkable energy conversion efficiency of ≈15.5% at a temperature difference of 449 K can be obtained in this segmented TE leg. Moreover, ASN can also be applied in fabricating n‐type PbTe‐Bi2Te3 segmented legs and multi‐pair TE devices, demonstrating the universality of this methodology. This work accelerates the development of robust, low‐cost, one‐step‐sintered segmented TE legs and promotes the use of eutectic alloys as "alloy glues" for advancing TE‐device connection technology. [ABSTRACT FROM AUTHOR]

The physical mechanism of self-organization of a multilayer nanolaminated coating based upon non-equilibrium (TiAlCrSiY)N/(TiAlCr)N nitride on a cutting tool during high-speed (600 m/min.) dry cutting of N13 steel is established. Using a set of modern surface analysis methods coating degradation and tribo-oxidation are studied within the running-in and steady stages of wear. It is shown that during cutting, amorphous-nanocrystalline films of oxides similar to Cr2O3, TiO2, Al2O3 (sapphire) and Al2O3 · 2 (SiO2) (mullite) are formed within a wear crater. Using computer calculations by a finite element method, heat transfer is considered in the cutting zone during formation of protective tribo-oxides. It is found that among all tribo-oxides, mullite has the best thermal barrier properties. Oxidation is the main adaptation mechanism of a cutting tool under extreme mechanical and thermal shock during high-speed cutting. The topography of chip contact surface is studied at various cutting stages, which makes it possible to establish a change in plastic deformation mechanisms of treated metal and friction cutting modes. Quantum chemical calculations of the electron structure of mullite show the highest degree of its electron polarization and explain the radical drop in friction coefficient during film formation upon a wear surface. In this case, mullite acts as a solid lubricant. [ABSTRACT FROM AUTHOR]

Rare‐earth tritellurides (RTe3) are popular for their charge density wave (CDW) phase, magnetotransport properties, and pressure‐induced superconducting state among other features. In this literature, Density functional theory is exploited to study various properties of NdTe3. The calculated elastic and thermomechanical parameters, which are hitherto untouched for any RTe3, uncover soft, ductile, highly machinable, and damage‐tolerant characteristics, as well as highly anisotropic mechanical behavior of this layered compound. Its thermomechanical properties make it a prospective thermal barrier coating material. Band structure, density of states, Fermi surfaces, and various optical functions of the material are reported. The band structure demonstrates highly directional metallic nature. The highly dispersive bands indicate very low effective charge carrier mass for the in‐plane directions. The Fermi surfaces display symmetric pockets, including signs of nesting, bilayer splitting among others, corroborating previous works. The optical spectra expose high reflectivity across the visible region, while absorption is high in the ultraviolet region. Two plasma frequencies are noticed in the optical loss function. The optical conductivity, reflectivity, and absorption reaffirm its metallic properties. The electronic band structure manifests evidence of CDW phase in the ground state. [ABSTRACT FROM AUTHOR]

Generally, thermal barrier and wear seriously affect flight safety by deforming or disabling the inner surface of the engine and outer surface of the vehicle of supersonic aircraft. In this study, we developed a bimetallic supported composite catalyst coating which can simultaneously eliminate the "thermal barriers" and improve the wear resistance. The bimetal-loaded composite catalysts (Pt-Cu@CeO2-Al2O3) coating was obtained by co-precipitation method. The catalytic cracking for RP-3 and wear resistance of composite catalyst coatings were evaluated via thermal cracking and friction experiments. The simulated catalytic cracking experiment results show that when n(Ce): n(Al) = 1:1, the composite catalyst exhibits the highest catalytic activity, which results from the largest specific surface area and proportion of strong acid centers. Meanwhile, under lower temperature conditions, the gas production rate of RP-3 catalytic cracking is increased by 915% (550 ℃) and 186% (600 ℃) compared with the thermal cracking. Meanwhile, the low frictional coefficient of 0.533 of the catalyst coating also indicates the satisfied wear resistance. This research provides useful information for the creation of a safer flying environment and the extension of the service life of supersonic aircraft. [ABSTRACT FROM AUTHOR]

Rare‐earth tritellurides (RTe3) are popular for their charge density wave (CDW) phase, magnetotransport properties, and pressure‐induced superconducting state among other features. In this literature, Density functional theory is exploited to study various properties of NdTe3. The calculated elastic and thermomechanical parameters, which are hitherto untouched for any RTe3, uncover soft, ductile, highly machinable, and damage‐tolerant characteristics, as well as highly anisotropic mechanical behavior of this layered compound. Its thermomechanical properties make it a prospective thermal barrier coating material. Band structure, density of states, Fermi surfaces, and various optical functions of the material are reported. The band structure demonstrates highly directional metallic nature. The highly dispersive bands indicate very low effective charge carrier mass for the in‐plane directions. The Fermi surfaces display symmetric pockets, including signs of nesting, bilayer splitting among others, corroborating previous works. The optical spectra expose high reflectivity across the visible region, while absorption is high in the ultraviolet region. Two plasma frequencies are noticed in the optical loss function. The optical conductivity, reflectivity, and absorption reaffirm its metallic properties. The electronic band structure manifests evidence of CDW phase in the ground state. [ABSTRACT FROM AUTHOR]

Introduction: In Switzerland, heating accounts for 70% of a building’s energy consumption, mostly fueled by fossil sources. Recently, cantonal regulations have mandated the use of renewable energy in heating, making heat pumps more significant. This study examines how public and private actors can create or transform a business ecosystem to facilitate heat pump adoption in multifamily houses and which business models, resources, and activities are most effective to support this transformation. Methods: We conducted a literature review and 13 semi-structured interviews with experts in heat pumps and contracting business models. The interviews were analyzed using an ecosystem framework. Results: Our findings revealed three primary barriers to the adoption of heat pumps in MFHs: technical challenges, lack of expertise, and regulatory issues. In terms of contracting business models, high transaction costs and customer acceptance are significant obstacles. Additionally, we discovered that in Switzerland, contracting is predominantly offered by public-oriented organizations with ready access to capital. Discussion: The study emphasizes the necessity for collaboration among various actors to facilitate the implementation of contracting solutions with the goal of accelerating the adoption of heat pumps in multifamily housing. Key activities include generating the necessary expertise and standardizing large heat pumps in MFHs, central government efforts to harmonize and facilitate HP regulations across cantons, as well as active communication and sensitization of building owners and users. [ABSTRACT FROM AUTHOR]

Halloysite nanotubes (HNTs) have attracted considerable attention due to their unique properties and wide range of applications. This review explores HNT‐based nanocomposites, focusing on their preparation methods and improvements in mechanical, thermal, and barrier properties. Various synthesis techniques, including solution mixing, melt compounding, in situ polymerization, and surface modification, are discussed, along with their benefits and limitations. The role of HNT characteristics such as aspect ratio, dispersion, and surface chemistry in enhancing nanocomposite properties is examined. HNTs significantly boost mechanical properties, including tensile strength, Young’s modulus, and toughness, due to their reinforcement effects. Improved dispersion and interfacial adhesion between HNTs and the polymer matrix enhance these properties. HNTs also act as thermal barriers, improving heat resistance and dimensional stability, while enhancing barrier properties against gases and moisture. These synergistic effects allow for the customization of nanocomposites for specific applications in packaging, automotive, electronics, and biomedical fields. Future research should focus on optimizing synthesis methods and processing techniques to further improve HNT‐based nanocomposites’ performance. This review provides a comprehensive overview of HNT‐based nanocomposites, offering valuable insights for advancing nanomaterials science and engineering. [ABSTRACT FROM AUTHOR]

The current study explores the fabrication of 3D printing filament using waste glass powder (WGP) and high-density polyethylene (HDPE) thermoplastic aiming to enhance the mechanical properties and sustainability of the composite material. The matrix and filler were blended in varying weight ratios (HDPE: WGP) of 100:0, 95:5, 90:10, 85:15, and 80:20 to prepare a raw material for filament extrusion. The filament of diameter 1.65 ± 0.05 mm diameter was extruded. Thereafter, a chemical and thermo-mechanical characterization of extruded filament was conducted. Fourier-transform infrared spectroscopy (FTIR) analysis confirmed the successful integration of WGP into the HDPE matrix, while X-ray diffraction (XRD) examination revealed alterations in crystallinity attributed to WGP reinforcement. Thermogravimetric Analyzer (TGA) analysis demonstrated enhanced thermal stability upon WGP incorporation, which is attributed to its role as a thermal barrier. Tensile test exhibit 45.41% and 17.22% increase in yield stress and ultimate tensile stress for 90:10 composition ratio, respectively. Moreover, including waste glass powder in HDPE, thermoplastic composite offers a sustainable solution for repurposing glass waste, thereby reducing the volume of glass destined for landfills or incineration. Potential applications of this composite filament include its use in construction, automotive, and packaging industries through 3D printing, where improved mechanical properties and sustainability are highly valued. [ABSTRACT FROM AUTHOR]

High-entropy ceramics have sparked renewed interest in compositionally complex ceramics since the first introduction in 2015. The kaleidoscopic array of compositions and structures harnessed by this idea has unlocked an unprecedented opportunity to tailor materials for specific applications, including catalysis, thermal barriers, and electrochemical energy storage. Within the family of oxides, a competition exists between rock-salt and spinel structures. The rock-salt structure is highly symmetrical, consisting of a single cation sublattice, while the spinel structure offers more flexibility to accommodate various cations in two distinct sublattices. Herein, we aimed at stabilizing and expanding the thermal stability range of the spinel-structured oxide, successfully synthesizing novel, single-phase, compositionally complex materials by capitalizing on entropy stabilization, all while avoiding the ubiquitous use of nickel and chrome, notorious for their negative environmental impact. The right combination of cations resulted in the synthesis of a seven-metal oxide that is thermally stable up to the remarkable temperature of 1473 K. [ABSTRACT FROM AUTHOR]

The spatial configuration of thermal habitats constrains the thermoregulatory performance of ectotherms. Thermal landscapes also vary through time, which is particularly relevant in seasonal environments such as temperate lakes. Indeed, elevated temperatures in the epilimnion of dimictic lakes during summer could substantially reduce the use of this habitat by cold‐stenothermic fish during the stratified period. The main objective of this study was to evaluate whether thermal habitat fragmentation in stratified lakes modulates accessibility to resources that brook charr, Salvelinus fontinalis, which is a mobile consumer, can track across seasons. More specifically, we hypothesize that reduced access to the littoral habitat during summer enhances foraging opportunities in this habitat during winter. We used an automatic acoustic telemetry system offering full coverage of the lake to continuously record brook charr locations across seasons, and we estimated zoobenthos abundances in the littoral habitat using image processing and semi‐automatic classification. While brook charr concentrate in the metalimnion of the pelagic habitat in summer, most individuals in winter shift to a shallow bay that is unexploited in summer due to thermal constraints. In this habitat, zoobenthos abundance is more than twice as high at the end of the summer compared to littoral habitats close to the thermal refuge in the pelagic habitat. Surprisingly, brook charr showed strong within‐lake site fidelity between two consecutive summers, which suggests that spatial memory could be a key driver of seasonal habitat use in this lacustrine population. Overall, our results suggest that thermal barriers create fragmentation between littoral and pelagic habitats that in turn produces resource opportunities that brook charr can track across seasons. [ABSTRACT FROM AUTHOR]

The current research is devoted to the development and characterization of green antimicrobial polymer biocomposites for food packaging applications. The biocomposites were developed by melt compounding on the basis of two different succinate polymer matrices with varying chain stiffness—polybutylene succinate (PBS) or its copolymer with 20 mol.% of polybutylene adipate (PBSA). Fungi chitosan oligosaccharide (C98) and crustacean chitosan (C95) were used as antimicrobial additives. The rheological properties of the developed biocomposites were determined to clear out the most suitable temperature for melt processing. In addition, mechanical, thermal, barrier and antimicrobial properties of the developed biocomposites were determined. The results of the investigation revealed that PBSA composites with 7 wt% and 10 wt% of the C98 additive were more suitable for the development of green packaging films because of their higher ultimate elongation values, better damping properties as well as their superior anti-microbial behavior. However, due to the lower thermal stability of the C98 additive as well as PBSA, the melt processing temperatures of the composites desirably should not exceed 120 °C. Additionally, by considering decreased moisture vapor barrier properties, it is recommended to perform further modifications of the PBSA-C98 composites through an addition of a nanoclay additive due to its excellent barrier properties and thermal stability. [ABSTRACT FROM AUTHOR]

When optical imaging-guided aircraft flies at hypersonic speeds in the atmosphere, the optical window withstands severe aerodynamic heating. Conducting the thin film resistance thermometer measurements in a hypersonic gun wind tunnel with a Mach number of 7.1 and total temperature of 670 K, the study investigates the effect of nozzle pressure ratio (NPR = film exit static pressure/nearby mainstream static pressure) on supersonic (Mach 2.43) film cooling for the hypersonic optical window. By combining the flow information near the window obtained using the three-dimensional compressible Reynolds-averaged Navier–Stokes method, the study reveals the mechanism of the effect of NPR on film cooling. The results indicate that increasing NPR can enhance the momentum of the unit volume film and improve the film's ability to resist mainstream mixing. Moreover, the film with a large NPR can better maintain its own momentum, leading to an increase in the film effective cooling length and film cooling effectiveness. The film effective cooling length corresponding to the unit mass flow rate of the cooling gas increases with the increase in NPR. It verifies the nonlinear relationship between the film cooling performance and the coolant mass flow rate, indicating the additional benefits of increasing NPR on the film cooling performance. Through research, it is found that increasing NPR can increase the film thickness, thereby enhancing its ability to isolate the mainstream. Moreover, as NPR increases, the cooling film expands, objectively leading to the widening of the film flow channel, allowing the Mach number of the supersonic film to increase continually. This further reduces the static temperature of the film in the flow field, thereby enhancing its cooling capability for the mainstream. [ABSTRACT FROM AUTHOR]

Fiber-reinforced aerogel composites are widely used for thermal protection. The properties of the fibers play a critical role in determining the structure and properties of the final aerogel composite. However, the effects of the fiber's characteristics on the structure and properties of the aerogel composite have rarely been studied. Herein, we prepared quartz fiber felt-reinforced silica-polybenzoxazine aerogel composite (QF/PBSAs) with different fiber diameters using a simple copolymerization process with the ambient pressure drying method. The reasons for the effects of fiber diameter on the structure and properties of the aerogel composites were investigated. The results showed that the pore structure of the aerogel composites was affected by the fiber diameter, which led to significant changes in the mechanical behavior and thermal insulation performance. At room temperature, pore structure and density were found to be the main factors influencing the thermal conductivity of the composites. At elevated temperatures, the radiative thermal conductivity (λr) plays a dominant role, and reducing the fiber diameter suppressed λr, thus decreasing the thermal conductivity. When the QF/PBSAs were exposed to a 1200 °C butane flame, the PBS aerogel was pyrolyzed, and the pyrolysis gas carried away a large amount of heat and formed a thermal barrier in the interfacial layer, at which time λr and the pyrolysis of the PBS aerogel jointly determined the backside temperature of the composites. The results of this study can provide valuable guidance for the application of polybenzoxazine aerogel composites in the field of thermal protection. [ABSTRACT FROM AUTHOR]

The influences of bubbling tube length, gas volume and position on glass flow are analyzed and optimized by numerical simulation. The results show that the effect of bubbling on the relatively stationary layer in circulation I is related to the tube length and gas volume of bubbling. Larger bubbling gas volume indicates that the range of action below the bubbling nozzle is deeper. Thus, the relationship between gas volume and its action area is established on the basis of the aforementioned observation. In addition, the bubbling position significantly affects the "thermal barrier" on the spring zone. Moreover, bubbling can only play a beneficial role on the glass furnace when appropriate distance is maintained between the bubbling and spring zone. Combined with the simulation optimization results and the bubbling viewpoint proposed in Part 1, the bubbling parameters of a production line in China were optimized, and the stripe images of the glass products with bubbling before and after optimization were compared and verified. The obtained results were consistent with the simulation results. This work provides a valuable reference for the early design and construction of a furnace and its optimization adjustment after production. It also reflects the importance of rational distribution of glass flow with bubbling in the furnace on the quality of the glass product. [ABSTRACT FROM AUTHOR]

The present study focuses on the fabrication and characterization of cerium oxide (CeO2)-doped yttria-stabilized zirconia (YSZ) composite particles, aiming to enhance the durability of thermal barrier coatings (TBCs) in high-temperature applications such as gas turbines and aircraft engines. The incorporation of CeO2 into the YSZ matrix was motivated by the need to address the limitations of YSZ coatings, particularly their phase transformation and thermal degradation at temperatures exceeding 1300 °C. The synthesis of a composite with a core–shell structure, where CeO2 is doped into YSZ particles, was pursued to improve the thermal stability and reduce the thermal conductivity of the material. The fabrication process involved surface treatment of YSZ particles with HCl and NH4OH to enhance their dispersion characteristics, followed by the adsorption of CeO2 nanoparticles precipitated from Ce precursors. The study revealed a reduction in the average particle size and improved the dispersion stability of the surface-treated YSZ. Notably, base-treated YSZ exhibited increased CeO2 adsorption due to the strong interaction between Ce ions and surface hydroxyl groups. The successful formation of the YSZ@CeO2 core–shell structure was confirmed through XRD, HR-TEM, and SAED analyses. The study suggest that base-treated YSZ@CeO2 composites have the potential to extend the operating life and improve the performance of TBCs under extreme temperature conditions, which may contribute to the development of more resilient thermal barrier systems. [ABSTRACT FROM AUTHOR]

This paper examines the water-vapour diffusion resistance (Z-value) of vapour versus wind barriers by determining their Z-value ratio in exterior wood-frame walls thermally insulated with six different materials to prevent mould growth. Using WUFI Pro, the water-vapour diffusion resistance requirements were determined for thermal insulation using mineral wool and biogenic materials: wood fibre, straw, flax, grass, and hemp. Hygrothermal simulations determine the minimum Z-value ratio between these materials with vapour versus wind barriers in temperate and cold climates. Wind barriers with Z-values between 1 and 8 GPa s m2/kg were used in walls with U-values of 0.15 and 0.10 W/m2 K. The indoor moisture load was defined from classes of 1 to 5 with a U-value of 0.15 W/m2 K and classes of 2 and 3 were used for a U-value of 0.10 W/m2 K. The Z-value ratio depends on the Z-values of the wind barrier and thermal insulation material, moisture load class, and U-value. The required Z-value ratio declines with an increased wind-barrier Z-value. The vapour-barrier Z-value approaches a fixed threshold for wind-barrier Z-values approaching lower values (1 GPa s m2/kg) and those approaching higher values (8 GPa s m2/kg), depending on the thermal insulation material. This parameter study examines wind barriers with a Z-value ranging between 1 and 8 GPa s m2/kg, which characterises typical wind barriers used in Denmark For the water-vapour diffusion resistance requirement of the vapour barrier, the Z-value increases for increased moisture load classes and thermally insulated walls with lower U-values. The conversion between the Z-value, the Sd-value, and the water-vapour resistance factor µ can be found in DS/EN ISO 12572:2016. [ABSTRACT FROM AUTHOR]

This study investigates the effects of inorganic flame retardants, zinc borate, and magnesium hydroxide, on the thermal, morphological, flame retardancy, and mechanical properties of polypropylene (PP)/calcium carbonate composites for potential construction industry applications. Polypropylene/calcium carbonate (50 wt.%) composites containing 5 and 10 wt.% flame retardants were prepared using a batch mixer, followed by compression moulding. The results demonstrated enhanced thermal stability, with the highest char residue reaching 47.2% for polypropylene/calcium carbonate/zinc borate (10 wt.%)/magnesium hydroxide (10 wt.%) composite, a notably strong outcome. Additionally, the composite exhibited an elevated limited oxygen index (LOI) of 29.4%, indicating a synergistic effect between zinc borate and magnesium hydroxide. The proposed flame retardancy mechanism suggests that the flammability performance is driven by the interaction between the flame retardants within the polypropylene/calcium carbonate matrix. Magnesium hydroxide contributes to smoke suppression by releasing water, while zinc borate forms a protective glassy foam that covers the burning surface, promoting char formation and acting as a physical barrier to heat transmission and fire spread. Scanning electron microscopy confirmed good dispersion of the additives alongside calcium carbonate within the polymer matrix. Despite the addition of up to 10 wt.% flame retardants, the composites maintained high-notched impact strength. [ABSTRACT FROM AUTHOR]

The utilization of an actively cooled thermal protection system is widely recognized as an effective approach to decrease the temperature of components exposed to severe aerodynamic heating. In this study, two cooling schemes with different flow paths and structural configurations were proposed, and six cooling channel designs were developed by modifying the leading-edge details. A numerical analysis on the heat transfer and thermal–mechanical performance was conducted under actual flight conditions (30 km altitude, Mach 8). The results highlight an optimal design scheme that balances temperature control and minimized coolant flow rates. The channel flow field demonstrated its superiority by effective convective heat transfer and improved fluid mixing facilitated through recirculation zones and turbulence at the bends. Structural assessments showed that the optimal scheme not only provided better cooling but also preserved the structural integrity. Overall, the study offers a practical and effective thermal protection approach for air rudders subjected to severe heat. [ABSTRACT FROM AUTHOR]

A composite silicone emulsion-biomass polymer paper-based barrier coating material with high barrier performance was prepared by double-layer coating, and the material was tested for oil repellency. The composition-structure-property data set of the paper-based barrier materials was constructed based on the experimental data. An adaptive neuro-fuzzy inference system (ANFIS) was used to construct a prediction model of the coating structure in high-temperature environments to achieve quantitative analysis of the barrier performance in high-temperature environments. The ANFIS prediction model was constructed based on two algorithms, the grid partitioning algorithm and the subtractive clustering algorithm, and the accuracy of the model determined by the two algorithms was compared for training, validation and testing of this experimental data. The results showed that the prediction model of the grid partitioning method had a better fit with the experimental data, with a root mean square error (RMSE) value of 7.00383 and a R-squared (R2) of 0.9644 between the model prediction data and the actual data. [ABSTRACT FROM AUTHOR]

Summary: In view of the environmental problems resulting from plastic‐based packaging, gelatin film production from alternative, sustainable sources are extremely important. The objective of this study was to utilise a major source of collagen derived from poultry waste to produce and characterise turkey skin gelatin films (TGF). TGFs were produced at different glycerol concentrations (20%, 30% and 40%) via solvent casting technique. TGFs characteristics were also compared with the bovine gelatin films (BGF). The thermal structural development of TGF solutions to form a film network was not affected by the glycerol content in the temperature sweep test. This property was determined earlier and at higher temperatures in TGF (22 °C–23 °C) than in BGF (19 °C). As the glycerol ratio increased, the moisture content increased from 14.80% to 22.46%, while the thickness (36 μm) and density (1.134–1.247 g cm−3) of TGFs remained constant due to the compact structures. The water vapour transmission rates of TGFs and BGF were similar (P >0.05), ranging from 0.48 to 0.53 g mm m−2 h−1 kPa−1. Lower solubility was found for TGF20 (44.78%) and TGF30 (63.59%) films compared to BGF30 (63.59%). TGF20 exhibited the highest tensile strength and lowest elongation at break values. TGF40 and BGF30 demonstrated the highest flexibility and extensibility (P >0.05). In XRD analysis, TG40 demonstrated a less amorphous film structure compared to BG30, since the increased interaction due to glycerol provided a more ordered polymeric structure. TG20 and TG30 showed lower decomposition rates and higher residue levels, indicating their higher thermal stability. Thus, gelatin films based on turkey skin could be the alternative natural biodegradable films with suitable glycerol content for desired mechanical, barrier and thermal properties. [ABSTRACT FROM AUTHOR]

Wall pressure fluctuations beneath turbulent boundary layers are a fundamental source of aerodynamic noise by exciting the wall structure, with their space-time characteristics serving as the basic ingredient for predicting the wall structural response. To this end, direct numerical simulations of fully developed compressible turbulent boundary layers at Mach numbers of 0.5, 1.2, and 2.0 are conducted to investigate wall pressure fluctuations comprehensively. The effects of Mach number on the single-point statistics of wall pressure fluctuations, such as the root mean square, skewness and flatness factors, probability density function, and frequency spectrum, are assessed to be very weak. Regarding the space-time characteristics, the convection velocity Uc determined by the space-time correlation of wall pressure fluctuations increases slightly with the Mach number, which only reflects the convective behavior of turbulent vortices. On the wavenumber–frequency spectrum, characteristic peaks of both the acoustic wave and convective vortices are identified. At Mach 0.5, the peaks of the fast (U c + c) and slow (U c − c) acoustic waves are unattached to others with c denoting acoustic speed, while only the peak of the fast acoustic wave is distinguishable from the convective peak at Mach 1.2 and 2.0. Due to the aerodynamic heating at supersonic conditions, the thermal effect on acoustic speed should be taken into account in determining the acoustic wavenumber. By introducing a convective Prandtl–Glauert parameter, a refined relation is proposed to provide a more accurate depiction of the acoustic domain in the wavenumber–frequency spectrum. [ABSTRACT FROM AUTHOR]