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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]

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]

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]

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]

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]

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]

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]

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]

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. [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]

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]

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]

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]

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]

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]

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 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 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]

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]

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]

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]

Copyright of Journal of Ordnance Equipment Engineering is the property of Chongqing University of Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

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Liner materials have extensive applications in automobile industry, packaging, and aeronautics. One of the specific uses of such materials is in thermal barrier, coating rockets, missile, and other systems used in space and defense. Each liner material exhibits different properties according to their chemical structure and composition. In this study, accelerated thermal aging of the liner material, silicone‐hollow glass microsphere composite (SHGC) has been studied along with the determination of its life span. The effect of such aging on the thermal properties of SHGC has been studied using thermogravimetry. Activation energy of the process has been determined to be in the range of 45–55 KJmol−1. The results have been compared with already reported silicon polymers. Shelf‐life of SHGC composite has also been determined using Arrhenius model. Stochastic model has been applied to determine the lower and upper limits of shelf‐life. Shelf‐life of SHGC is found to be 24 years with 28 and 18 years of upper and lower error limits. [ABSTRACT FROM AUTHOR]

AbstractIn our research described in this paper, the metal-organic framework MOF-2 [Zn2(BDC)2] was used to enhance the properties of a biodegradable blend based on poly(lactic acid) (PLA) and poly(butylene adipate-co-terephthalate) (PBAT). PLA/PBAT/(1, 3, 5, and 7 wt%) MOF-2 blends were prepared using a melt blending technology with a twin-screw extruder. The phase morphology, rheological behavior and barrier properties of the blends were studied. X-ray diffraction (XRD) showed a slight increase in the crystalline content of the PLA/PBAT matrix with increasing MOF-2 content. Scanning electron microscopy (SEM) revealed that the PLA/PBAT blend was immiscible, and the phase morphology improved with MOF-2 by enhancing the interfacial compatibility, reducing the size of micro-domains and cavities, and promoting a transition to a co-continuous morphology, indicating better miscibility. The ternary nanocomposites with 5 and 7 wt% MOF-2 showed increased complex viscosity (η*) and storage modulus (G′) compared to those with 1 and 3% MOF-2, indicating stronger percolated networks. The thermal and barrier properties and water absorption capacity were also improved, confirming the rheological measurements. All the results showed that the PLA/PBAT/MOF-2 nanocomposites could be used in the field of packaging. [ABSTRACT FROM AUTHOR]

Buildings consume significant energy, much of which is used for heating and cooling. Insulation reduces undesired heat transfer to save on heating and cooling energy usage. Radiant barriers are a type of insulation technology that reduces radiant heat absorbed by a structure. Applying radiant barriers to buildings reduces costs and improves both energy efficiency and occupant comfort. However, homes often have favorable thermal gradients that could also be used to reduce energy usage if the insulation properties were switched dynamically. This article introduces two dynamic radiant barriers intended for residential attics, which can switch between reflecting and transmitting states as needed. These radiant barriers are manufactured as a single deformable assembly using sheet materials and are compatible with various actuation mechanisms. The efficacy of these radiant barriers is reported based on a hotbox experiment and numerical calculations. The experimental results demonstrate that both proposed dynamic radiant barrier designs increase effective thermal resistance by factors of approximately 2 when comparing insulating to conducting states, and by approximately 4 when comparing the insulating state to the case without a radiant barrier. Additionally, the dynamic radiant barriers achieve heat flux reductions up to 41.9% in the insulating state compared to tests without a dynamic radiant barrier. [ABSTRACT FROM AUTHOR]

Natural and renewable polymers are gradually replacing petroleum-based plastics, mostly as a result of environmental concerns. Moreover, upcycling industrial food waste into new added-value products is a creative approach that is crucial for cleaner and more sustainable manufacturing. The aim of this study was to obtain an environmentally friendly biodegradable film using a combination of k-carrageenan (KCAR) and chicken gelatin (CGEL), which obtained from poultry by-products. The effects of varying concentrations of KCAR (0–2%) on the physical, permeability, textural, thermal, and microstructural properties of CGEL/KCAR composite films were evaluated. The findings demonstrated that an increase in KCAR enhanced the lightness and opacity levels of the films. Water vapor permeability (WVP) values reduced as the KCAR concentration increased. The lowest WVP value (0.0012 g.mm/h.m2.kpa) was seen in the treatment with 2% KCAR. Tensile strength (TS) values increased with increasing KCAR. The films' thermal stability was increased by the addition of KCAR. Microstructure assessments revealed a more compact and smooth structure in the KCAR-containing treatments, indicating improvements in WVP, thermal stability, and TS. Compared to the commercial cattle gelatin film, the CGEL film had higher TS and lower water solubility (WS). Overall, this study showed that the physical, mechanical, barrier and thermal and microstructural qualities of gelatin-based films may be enhanced by combining CGEL and KCAR to create an effective biodegradable film. Moreover, the comparison study between commercial cattle and chicken gelatin films revealed that cross-linked chicken gelatin films would be a suitable alternative for bovine gelatin films in the production of biodegradable film. [ABSTRACT FROM AUTHOR]

In this work we report the synthesis, structural characterization and magnetic properties of a family of butterfly complexes {Cr2Ln2} with Ln = Tb (4), Ho (5), Er (6), Tm (7) and Yb (8), extending the family of previously reported isostructural compounds with Gd (1), Dy (2) and Y (3). As in 1 and 2, an anti-ferromagnetic Cr(III)–Ln(III) exchange interaction is found. For oblate ions 4 and 5, SMM behavior with a purely Orbach relaxation mechanism is observed with thermal barriers of 38 cm−1 (4) and 32 cm−1 (5). Complex 4 displays hysteresis opening up to 2.4 K with loss of magnetization at zero field. The prolate complex ions 6 and 7 are field-induced SMM's with dominant Orbach, direct and QTM relaxation mechanisms. Compound 8 did not show SMM properties. [ABSTRACT FROM AUTHOR]

In this study, a tunnel model with a length of 20 m, a width of 5 m, and a height of 5 m was used, and an experimental investigation was conducted to examine the impact of high-pressure water mist on the temperature distribution along the tunnel ceiling. Specifically, different experimental settings, such as various nozzle pressures, nozzle positions, and longitudinal ventilation speeds, in the high-pressure water mist system were employed to investigate the smoke-spreading process of tunnel fire under different conditions, and an effective method utilizing a high-pressure water mist system was proposed for blocking smoke and heat. The experimental results reveal that the high-pressure water mist system can be used to effectively improve the ceiling temperature during tunnel fires; when the nozzle pressure is set as 10 MPa, and the nozzle position is located at x7, the highest thermal insulation efficiency in the tunnel is obtained. Additionally, the joint application of the high-pressure water mist system and the mechanical smoke exhaust effectively mitigates the ambient temperature within the tunnel, thereby playing a pivotal role in enhancing the fire safety of the tunnel. [ABSTRACT FROM AUTHOR]

Summary: Starch nanocrystals (SNCs) have emerged as promising biodegradable nanomaterial for the enhancement of biopolymer films' properties. Nevertheless, using SNCs alone is difficult due to restricted capacity for nanocrystal integration within the film's matrix. The objective of this study was to enhance the properties of biopolymer films using waxy corn starch nanocrystals supplemented with stearic acid. Cassava starch films containing varying proportions of SNCs (0–20 wt.% starch) and steric acid (2%) were prepared and characterised. The inclusion of stearic acid substantially improved SNC integration from 5% to 15%, yielding nanocomposite films with better tensile strength, thermal stability and barrier properties than those prepared with native starch or starch‐fatty acid alone. The improvement in film properties was attributed to V‐amylose complexes formation, increased crystallinity and hydrophobicity. Microscopy images revealed homogenous film surfaces, depicting greater nanocrystal dispersibility. The supplementation of lipid additives offers a valuable strategy to improve the integration of SNCs in film matrices. [ABSTRACT FROM AUTHOR]

Ultrafast laser technology has moved from ultrafast to ultra-strong due to the development of chirped pulse amplification technology. Ultrafast laser technology, such as femtosecond lasers and picosecond lasers, has quickly become a flexible tool for processing brittle and hard materials and complex micro-components, which are widely used in and developed for medical, aerospace, semiconductor applications and so on. However, the mechanisms of the interaction between an ultrafast laser and brittle and hard materials are still unclear. Meanwhile, the ultrafast laser processing of these materials is still a challenge. Additionally, highly efficient and high-precision manufacturing using ultrafast lasers needs to be developed. This review is focused on the common challenges and current status of the ultrafast laser processing of brittle and hard materials, such as nickel-based superalloys, thermal barrier ceramics, diamond, silicon dioxide, and silicon carbide composites. Firstly, different materials are distinguished according to their bandgap width, thermal conductivity and other characteristics in order to reveal the absorption mechanism of the laser energy during the ultrafast laser processing of brittle and hard materials. Secondly, the mechanism of laser energy transfer and transformation is investigated by analyzing the interaction between the photons and the electrons and ions in laser-induced plasma, as well as the interaction with the continuum of the materials. Thirdly, the relationship between key parameters and ultrafast laser processing quality is discussed. Finally, the methods for achieving highly efficient and high-precision manufacturing of complex three-dimensional micro-components are explored in detail. [ABSTRACT FROM AUTHOR]

The inflatable membrane reentry vehicle (IMRV) is one of the innovative aircrafts for next-generation space transport systems because of its reduced aerodynamic heating. In this study, a three-dimensional (3D) thermochemical nonequilibrium model is developed for simulating air plasma flows around an IMRV. This 3D nonequilibrium model includes the coupling of Navier–Stokes equations, 11 species, and 20 chemical reactions of air, a two-temperature model, and shear stress transfer k–ω turbulent transport equations. The simulated results are validated and compared with the corresponding experimental and numerical data published. Generally, they agree well with each other. It is concluded that the flight attack angle of the IMRV has an important impact on the flight stability. When the IMRV flies at an angle of attack of 0°, the translational-rotational and vibrational-electronic temperatures increase rapidly in the surge layer and decrease gradually near the wall. The wall pressure and heat flux decrease gradually along the capsule from the head to the inflatable film, increase rapidly where the inflatable film joins the rings, and decrease rapidly after the shoulder. The chemical and thermal nonequilibrium model developed in this study might be an accurate, stable, and low-cost modeling tool required for the optimal design of hypersonic reentry vehicles. [ABSTRACT FROM AUTHOR]

Among the design requirements of hypersonic vehicles, reducing aerodynamic heating and drag force simultaneously is the main challenge. This paper proposes a novel spike aerodome-channel combination concept to realize the flow field reconstruction around the hypersonic blunt body. The novel configuration is investigated in the axisymmetric flow at a Mach number of 6 at zero angle of attack. The two-dimensional Reynold-averaged Navier–Stokes equations are numerically solved, and the shear-stress transport k–ω model is the turbulence model implemented in this study. Parameters such as spike length and lateral jet location are investigated to explore the drag and heat reduction performance and the flow control features. The obtained results show that the application of the novel spike aerodome-channel concept alters the flow field by eliminating or replacing the strong bow shock wave, and the design of hypersonic vehicles can benefit from the application of the proposed concept. The blunt body coupled with a frustum of cone-tipped spike-channel configuration provides a remarkable drag reduction effect of 20.71% with respect to the case without channel. Considering the effect of lateral jet location, the drag reduction performance of the case with LR = 0.75 is superior to that of the root jet case at the same spike length, and a considerable drag reduction of 28.93% is obtained with L/D = 2.4. In addition, longer spike length is beneficial for improving drag reduction performance, while excellent efficiency of heat protection is obtained in a certain spike length range. For the case of L/D = 1.6 with root jet, the peak Stanton number is significantly decreased by 33.51%. [ABSTRACT FROM AUTHOR]

Context: The mechanisms for the formation of the first C − C bond and lower olefins on methanol to olefins (MTO) conversion on H-ZSM-5 had been focused in dispute. In this paper, density functional theory has been used to study the reaction mechanisms of methanol to olefins on ZSM-5. The configurations of reactants, intermediates, products and transition state of the numerous reactions involved in such a process have been optimized, as well as the elementary reactions related to these configurations were determined by the calculation of corresponding activation energy barriers and reaction heats. Here, two different kinds of the mechanisms were proposed for the formation of dimethyl ether (DME), one involving an associative interaction of two methanol molecules with the zeolite Brønsted acid sites and the other occurring via a surface methoxy species and a methanol molecule. A critical intermediate of the methoxy methyl cation was theoretically verified by the reaction of the methoxy species and dimethyl ether. Besides, it was found that the first intermediates containing a C − C bond were 1,2-dimethoxyethane and 2-methoxy-ethanolare, in which the former was formed from methoxy species with dimethyl ether and the latter was formed from methanol by onium ions((CH3)2O+CH2CH2OCH3), respectively. For the whole reaction mechanism, the results in this paper indicated that the ethene formation is more favorable than propylene formation due to the low activation energy barrier for ethene formation (123.49 vs. 162.09 kJ.mol−1). From these calculations, it would be concluded that ethene is the first alkene product that induces the occurrence of the hydrocarbon pool mechanism. Methods: All the periodic density function theory (DFT) calculations were performed by the Vienna Ab Initio Simulation package (VASP). The interaction between nucleus and valence electron was described using the pseudopotentials found in the projector augmented wave (PAW) method. PBE-D3 was used in the whole DFT calculations and CI-NEB was used to locate transition state. [ABSTRACT FROM AUTHOR]

Yttria-stabilized zirconia (YSZ) oxide ceramic powder is a thermal-barrier material used to fabricate thermal barrier coatings (TBC). In this study, to improve the electromagnetic wave (EMW) absorbing properties of TBCs, microwave-absorbing samarium iron nitrogen (SmFeN) particles were used to prepare SmFeN/yttria-stabilized zirconia (YSZ) composites. To study the effect of the SmFeN/YSZ interfaces on the EMW-absorbing properties of the SmFeN/YSZ composite, SmFeN/YSZ interfaces were built in different ways in composite materials having the same mass ratio of 1:1, for example, SmFeN and YSZ particles homogeneously mixed together, SmFeN/YSZ interfaces perpendicular and parallel to the EMW incident direction, and different interfaces between YSZ and SmFeN. Thus, the microwave absorbing performance of the samples, including the electromagnetic parameters, attenuation coefficient, eddy-loss current (C 0), impedance matching, and minimum reflection loss (RL min) values were examined and analyzed. The results demonstrate that interfaces perpendicular to the direction of the EMWs can increase the contact area and enhance the interfacial absorption effect. Further, when the wave-absorbing agent was placed in the middle of the composite, its wave-absorbing effect was the best among all the samples, yielding RL min = −27.824 dB and effective absorption bandwidth (EAB) = 8.5453 GHz (effective absorption frequency range 7.9256–16.4709 GHz for a 7.2-mm-thick layer). Crucially, the frequency and bandwidth at which the best absorption occurred could be tuned by adjusting the thickness of the coating. This is because the interfaces in the samples resulted in polarization enhancement and anomalous dispersion, leading to large dielectric losses. Overall, the use of a coaxial measurement technique is highly efficient for EMW absorbing body design and process simulations. [ABSTRACT FROM AUTHOR]

The problem of increasing heat resistance and corrosion and erosion resistance of gas turbine units in compressor stations was solved through the development of new layered materials containing nanostructured grains. The authors carried out a destruction analysis of gas turbine units in compressor stations. It was shown that after 10–30,000 h of operation, the greatest damage occurred when the gas turbine operated in dusty environments at high temperatures (or in air environments with a high salt content). The developed layered composites include the thermal barrier and functional reinforced nanostructured layers consisting of refractory carbides and oxides. This paper describes the destruction mechanism of gas turbine units under the influence of high-temperature aggressive environments. As a result, a new formation technology for reinforced nanostructured layered composites has been developed. The developed composition makes it possible to increase the heat resistance of materials by approximately 10 times. This significantly increases the reliability and durability of gas turbine units in compressor stations. The structural and mechanical parameters of the layered nanostructured heat-resistant composites have been studied. [ABSTRACT FROM AUTHOR]

In this research, a streamlined numerical approach designed for the quick estimation of temperature profiles across the finite thickness of a hemispherical dome subjected to aerodynamic heating is introduced. Hemispherical domes, with their advantageous aerodynamic, structural, and optical properties, are frequently utilized in the front sections of objects traveling at supersonic velocities, including missiles or vehicles. The proposed method relies on one-dimensional analyses of fluid dynamics and flow characteristics to approximate the local heat flux across the exterior surface of the dome. By calculating these local heat flux values, it is also possible to predict the temperature variations within the thickness of the dome by employing the finite difference technique, to solve the heat conduction equation in spherical coordinates. This process is iterated over successive time intervals, to simulate the entire flight duration. Unlike traditional Computational Fluid Dynamics (CFD) simulations, the proposed strategy offers the benefits of significantly lower computational time and resource demands. The primary objective of this work is to provide an efficient numerical tool for evaluating aerodynamic heating impact and temperature gradients on hemispherical domes under specific conditions. The effectiveness of the proposed method will be validated by comparing the temperature profiles derived for a standard flight scenario against those obtained from 2-D axisymmetric transient CFD simulations performed using ANSYS-Fluent 2022 R2. [ABSTRACT FROM AUTHOR]

Binary gas diffusivities, DABs, are key parameters in the analysis of many chemical engineering processes. Significant efforts to estimate diffusivities experimentally were made by Josef Stefan in the 19th century, who designed a column with liquid A at the bottom overlaid by a gas phase through which gas A diffused. His studies led to the determination of DABs for many gas pairs (B is commonly air), and to the development of alternate mass transport systems. The present proof‐of‐concept theory describes a steady two‐dimensional (2D) diffusion model consisting of a vertical cylinder thinly coated on its inner surfaces with either a sublimating or evaporating species A. The gas‐phase mass conservation partial differential equation is rendered dimensionless and solved by separation of variables. The theoretical molar flow rate of species A at the top of the cylinder, calculated analytically, can be equated to the experimental rate of mass loss from the coated walls, ultimately leading to DAB. The solution of the steady 2D diffusion model is explored in terms of the cylinder aspect ratio (height/radius), showing that the latter quantity can be tailored to obtain preselected sublimation rates of A. The interplay of the radial and axial diffusion mechanisms is also demonstrated as a function of geometry. Finally, the model's use in analyzing a projected sublimation/evaporation–diffusion experiment is discussed. This is the first time that a steady 2D diffusive transport model has been proposed to estimate DABs from experimental data. [ABSTRACT FROM AUTHOR]

PDMS-based aerogel layers were synthesized as insulation layers by adopting mullite fiber (MF), hollow glass microspheres (HGM) and silica aerogel (SA) as the main fillers, and their loading amounts and content ratios were checked to investigate their effects on the thermal insulation properties in PDMS composites by thermal conductivity, thermal stability, and thermal insulation. The loading amount of nanofillers can significantly influence the insulation-layer performance, and the best performance with the lowest thermal conductivity of 0.0568 W/(m·K) was obtained by 10 wt% loading in PDMS with MF:SA:HGM = 2:2:1, which can achieve a temperature difference (∆T) of 67 °C on a 200 °C hotplate. Moreover, the variation of the filler content ratios can also affect the thermal insulation behavior when the loading amount is fixed at 10 wt%, and the best thermal barrier performance can be found for the sample with more SA as the filler (MF:SA:HGM = 1:3:1). The formed sample had the best thermal stability and thermal insulation property, which can stand a 9 min flame test without burning by butane spray gun, and the backside of the sample showed ∆T > 500 °C for the whole test. [ABSTRACT FROM AUTHOR]

To address the issue of electronic equipment failure inside the instrument compartment due to aerodynamic heating during high-speed flight. Combining the heat transfer characteristics of phase change materials, a new instrument compartment structure was proposed as the research subject based on phase change materials. While studying the heat transfer characteristics of this structure, one-dimensional phase change heat transfer theoretical model was constructed based on the Lightfoot integral equation method, and the corresponding analytical solution was obtained. To explore the temperature change law of the instrument compartment structure and verify the rationality of the theoretical model, the new thermal experiment was carried out for the instrument compartment structure. Compared with the aluminum alloy instrument compartment structure, the experimental results show that the instrument compartment structure design based on phase change materials could effectively reduce the temperature of the structure itself, and the experimental data are in good agreement with the theoretical calculation results, which verified the rationality of the theoretical model and provided a scientific basis for the practical application of phase change materials in instrument compartment structures. [ABSTRACT FROM AUTHOR]

Previous studies have confirmed the diverse spatiotemporal characteristics of Atlantic Niño events. Our research further reveals the crucial preparatory role of equatorial western Atlantic barrier layers (BL) and the triggering effect of westerly wind bursts (WWB) on different varieties of Atlantic Niño. Strong easterly winds typically facilitate the formation of thick BL by deepening isothermal layer depth in the western Atlantic through horizontal transport. The existence of BL accumulates the necessary heat for the onset of Atlantic Niño. Additionally, the timing of BL occurrences, the presence of easterly wind anomalies preceding WWB, and the duration of westerly wind anomalies jointly contribute to Atlantic Niño diversity. Persistent westerly wind anomalies following strong easterly winds often lead to Atlantic Niño events lasting over 6 months, while short‐lived events occur when westerly wind anomalies cease shortly after their onset. Plain Language Summary: The tropical Atlantic Ocean experiences significant year‐to‐year climate variability known as Atlantic Niño or Niña, similar to the warm and cold phases of El Niño–Southern Oscillation (ENSO) in the Pacific. Atlantic Niño has a considerable impact on local rainfall and cyclone activity. However, each instance of Atlantic Niño has unique spatiotemporal development characteristics, which can be classified into four varieties. While previous research has demonstrated that distinct preconditions give rise to different varieties of Atlantic Niño events, there hasn't been any investigation into the common factors among them. The salinity stratified isothermal layer between the base of the mixed layer and the top of the thermocline is referred to as the barrier layer (BL), which is a common feature of tropical western Pacific and Atlantic. The BL in the tropical western Pacific has been confirmed to facilitate the accumulation of heat in the upper ocean and can provide favorable thermal conditions for the onset of El Niño events. Our study reveals the key role of BL induced heat accumulation in various Atlantic Niño onsets. This suggests that anomalies of BL can be reliable indicators for predicting the onset of Atlantic Niño events. Key Points: The role of barrier layers in heat buildup is confirmed during the development of the four varieties of Atlantic NiñoThe heat buildup caused by barrier layers, combined with zonal wind events, regulates the diversity of Atlantic NiñoThe sustainability of westerly wind anomalies links to the strength of Atlantic Niño events [ABSTRACT FROM AUTHOR]

Antioxidant/antifungal active films based on bio-polyethylene (BPE) added with Nutrabiol®T90 and Tocobiol®Plus natural extracts rich in tocopherols at different concentrations (1 and 3 wt%) were developed by melt-blending followed by compression-molding. Thermal, barrier, mechanical, optical and functional properties of the developed active films were evaluated. The addition of active extracts did not cause important changes in thermal and barrier properties of active films whereas a significant increase in oxidative stability was found. Release kinetics of active additives migration showed higher tocopherol diffusion coefficient and antioxidant capacity, determined by the DPPH and ABTS methods, for films containing 3 wt% of Nutrabiol®T90. This film also delayed polymer oxidation in 260 min and extended strawberries shelf-life during storage for 7 days compared to neat BPE, showing a significant antifungal effect. The studied biomaterials offer great potential to substitute conventional petrol-derived materials at the industrial scale as active food packaging systems to increase the shelf-life of perishable foodstuff. [ABSTRACT FROM AUTHOR]

Interactions at high temperatures between thin films and the Si substrate limit materials discovery using combinatorial processing platforms (CPPs). To overcome this, a diffusion and reaction barrier, SiO2, by thermal oxidation of Si tips is developed. The application of this diffusion barrier in CPPs for atomic‐scale investigations of new materials in atom probe tomography is reported. Thermal SiO2 layers (20 and 50 nm thick) are examined as barriers to separate coatings from Si tips. Pt is chosen as it easily forms silicides. CPPs are sequentially annealed in vacuum at 400 °C for 10 h, 600 °C for 2 h, and 800 °C for 2 h. The thermal SiO2 diffusion barrier remains stable and prevents intermixing at least up to 800 °C. Moreover, it provides improved film adhesion as dewetting of Pt on the oxide surface occurred at 800 °C instead of 600 °C without a thermal diffusion barrier. A comprehensive structural and chemical analysis of the Pt film, the thermal SiO2 layer, and their interfaces is performed using scanning and transmission electron microscopy, and atom probe tomography. As a result, the thermal SiO2 forms a stable barrier, even at the lowest thickness of 20 nm, avoiding the formation of Pt silicides, even at 800 °C. [ABSTRACT FROM AUTHOR]

The demand for thermally insulating, ultraviolet (UV) shielding materials derived from natural resources to meet sustainable societal development is of utmost importance due to increased energy consumption and environmental concerns. Cellulose nanocrystals (CNCs) are currently regarded as one of the most intriguing green nanomaterials with tremendous application potential, owing to their availability, renewability, biodegradability and intrinsic biocompatibility. This work presents an efficient approach for the eco-friendly utilization of wastepaper (WP) through the extraction of CNCs from it. Also, the practical applicability of CNCs is explored through the investigation of thermal properties such as thermal diffusivity and thermal conductivity via a dual-beam mode mismatched thermal lensing (TL). The thermal diffusivity values of the dispersion of CNCs in water and ethanol are found to be 5.741 × 10–8 to 4.271 × 10–8 m2s−1 and 7.909 × 10–8 to 5.507 × 10–8 m2s−1, respectively. The results of the current study are expected to pave a new path for the development of forthcoming thermal insulation materials derived from environmentally benign and sustainable CNCs. [ABSTRACT FROM AUTHOR]

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]