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The Cantor alloy (equiatomic CrMnFeCoNi) is a high-entropy alloy with unique physical properties and radiation resistance. To model its response to intense laser pulses, the parameters of the electronic ensemble are required. In this work, the electronic heat capacity, thermal conductivity, and electron-phonon coupling strength at elevated electronic temperatures are evaluated using a combined approach that incorporates tight-binding molecular dynamics and the Boltzmann equation. The damage threshold fluence is estimated for a wide range of photon energies, from XUV to hard X-rays. It is found that at the electronic temperatures ~ 24,000 K (absorbed dose ~ 6 eV/atom), the Cantor alloy experiences nonthermal melting due to modification of the interatomic potential induced by electronic excitation, even without the increase of the atomic temperature. This effect must be included in reliable models of CrMnFeCoNi ablation under ultrafast laser irradiation.

The paper deals with the electronic heat capacity of iron monosilicide FeSi subjected to semiconductor–metal thermal transition during which the formation of its spintronic properties is observed. The proposed model which considers pd-hybridization of strongly correlated d-electrons with non-correlated p-electrons, demonstrates a connection of their contribution to heat capacity in the insulator phase with paramagnon effects and fluctuations of occupation numbers for p- and d-states. In a slitless state, the temperature curve of heat capacity is characterized by a maximum appeared due to normalization of the electron density of states using fluctuating exchange fields. At higher temperatures, a linear growth in heat capacity occurs due to paramagnon effects. The correlation between the model parameters and the first-principles calculation provides the electron contribution to heat capacity, which is obtained from the experimental results on phonon heat capacity. Anharmonicity of phonons is connected merely with the thermal expansion of the crystal lattice.

Research on phase change material (PCM) for thermal energy storage is playing a significant role in energy management industry. However, some hurdles during the storage of energy have been perceived such as less thermal conductivity, leakage of PCM during phase transition, flammability, and insufficient mechanical properties. For overcoming such obstacle, researchers have been concentrating on composite PCM, where PCM is combined with metal or non-metal particles, fibrous materials, expanded or porous materials, and flame retardants. The main purpose of the current paper is to review the properties enhanced paraffin-based composite PCM. In the literature review, paraffin is selected as a thermal energy storage material, which is mixed with property-enhancing material to prepare composite. Structural and thermal properties of composite have been explored with the help of scanning electron microscope, X-ray diffractometer, transmission electron microscope, polarizing optical microscope, Fourier transform infrared spectroscopy, thermogravimetric analysis, and differential scanning calorimetry. Mechanical properties of the material are also portrayed using different testing techniques. Nevertheless, numerical methods have also been adopted for characterization of composite. It is found from the literature review that with incorporation of property-enhancing material, thermal conductivity, phase transition rate, and shape stability of PCM increased at the same time flammability, heat storage capacity, and mechanical properties reduced. Graphical abstract

This study examines the thermophysical properties of ethylene glycol–glycerol (60:40 v/v) hybrid nanofluids containing graphene nanoplatelets (GNPs) and silver nanoparticles (Ag) at concentrations of 0.1–0.5 vol.%. The nanofluids were synthesized using a two-step method with Tween-80 surfactant to enhance dispersion stability. High-resolution transmission electron microscopy (TEM) and Raman spectroscopy confirmed the morphology, lateral size, few-layer structure of GNPs, and the attachment of Ag nanoparticles. The addition of surfactant increased the zeta potential from 15.7 mV to 35.2 mV for the 0.1 vol.% GNPs/Ag formulation, indicating a marked improvement in colloidal stability. Thermal conductivity enhancement reached 102.85% at 0.1 vol.% with only a 19.84% viscosity increase. Higher nanoparticle loadings improved conductivity further but caused significant viscosity increases and reduced stability. Specific heat capacity decreased by up to 46.45%, potentially benefiting rapid thermal response applications but limiting heat storage capacity. Comparison with recent literature showed that the present formulation outperforms several similar Ag- and GNP-based nanofluids in thermal conductivity enhancement while maintaining manageable viscosity. This study is the first to report such high conductivity improvement in an EG–GLY-based hybrid nanofluid at ultra-low loading, achieved through optimized surfactant use, validated structural characterization, and benchmarking against literature. Low-concentration GNPs/Ag hybrid nanofluids, particularly at 0.1 vol.%, offer strong potential for thermal management applications where high heat transfer performance and acceptable pumping requirements are critical. However, stability limitations at higher concentrations and viscosity–conductivity trade-offs highlight the need for further optimization before large-scale deployment.

This experimental study aimed to investigate the potential control of microstructural-mineralogical characteristics on thermal properties and its relation with the deformational behaviour in mild to high temperature (25°–800°C) regime of coal-bearing sandstone from an underground coal mine fire region. Barakar sandstone from Jharia Coalfield, India, one of the world's largest underground coal mine fire regions, was chosen. The thermal parameters and their relations to the mineralogical, microstructural, and damage characteristics of Barakar sandstone have been discussed. Thermal conductivity ( λ ), thermal diffusivity ( κ ), and specific heat capacity ( C p ) of heat-treated samples were determined using the transient plane source method. Additionally, detailed petrography, scanning electron microscopy, and electron probe micro-analyser were used to understand the thermal effect on mineralogy and microstructures. The deformational behaviour with elevated temperature was investigated through the universal testing machine. The obtained results suggest three characteristic temperature regimes: mild temperature regime (25°–300°C), transitional temperature regime (300º–500°C) and high temperature regime (500º–800°C). Moreover, prediction models for thermal properties have also been developed using multi-gene genetic programming (MGGP), considering physical properties as input parameters. In view of experimental constraints to determine the thermos-elastic properties of a rock due to tedious experimental processes, the proposed prediction models shall be very useful to indirectly estimate the thermal properties of sandstone rocks using easily determined physical parameters. The outcome of the present study may be useful to understand the subsidence induced by underground coalmine fire, which is a distressing issue in the Jharia region due to persistent coalmine fire.

Nowadays, to improve quality of life, to have a more comfortable life, in internal spaces we try to maintain conditions that are free from external environmental influences. Thus, existing as well as newly built houses have adequate interiors maintaining their temperature, warming, or cooling due to the environment compensation. One way to create this is to reduce the heat loss in buildings. An option to achieve this is the application of thermal insulations. Nowadays, the use of super insulation materials such as aerogel and vacuum insulation panels and other nano-structured insulations, such as graphite doped expanded polystyrene, is becoming increasingly justified. These are relatively new materials, and we know only a little about them. This paper presents research results based on temperature-induced investigations of nanostructured graphite expanded polystyrene, to reveal its thermal stability after long-term and short-term thermal annealing, simulating the ageing of the material. Firstly, with a differential scanning calorimeter, we will explore the thermal stability profile of the specimens. After this, the paper will present temperature-induced changes in both the thermal properties and the structure of the samples. We will also present changes in the thermal conductivity, modifications in the surface, and compressive property variation induced by thermal annealing. The samples were thermal annealed at 70 °C for 6 weeks, at 100 and 110 °C for 1 h. Besides the thermal conductivity measurements with Netzsch 446 heat flow meter equipment, we will present specific heat capacity measurement results executed with the same equipment. Moreover, sorption isotherms of the as-received and annealed samples were registered and completed with hydrophobic experiments, too. Furthermore, from the measurements, we showed that temperature should affect a significant change in the thermal conductivity of materials. Moreover, the changes in the graphite expanded polystyrene before and after thermal annealing were investigated by Scanning Electron Microscopy, as well as optical microscopy. The structural changes were further followed by an X-ray diffractometer and the IR absorption capability was tested, too.

This research focuses on the thermal characterization of 3D-printed parts obtained via fused filament fabrication (FFF) technology, which uses a poly(lactic acid) (PLA)-based filament filled with milled carbon fibers (MCF) from pyrolysis at different percentages by weight (10, 20, 30 wt%). Differential scanning calorimetry (DSC) and thermal conductivity measurements were used to evaluate the thermal characteristics, morphological features, and heat transport behavior of the printed specimens. The experimental results showed that the addition of MCF to the PLA matrix improved the conductive properties. Scanning electron microscopy (SEM) micrographs were used to obtain further information about the porosity of the systems.

In this study different nanofluids with phase change behavior were developed by mixing a molten salt base fluid (KNO3 selected as phase change material) with nanoparticles using the direct synthesis method. The thermal properties of the nanofluids obtained were investigated. Following the improvement in the specific heat achieved, these nanofluids can be used in concentrating solar plants with a reduction of storage material. The nanoparticles used (1.0 wt.%) were silica (SiO2), alumina (Al2O3), and a mix of silica-alumina (SiO2-Al2O3) with an average diameter of 7, 13, and 2–200 nm respectively. Each nanofluid was prepared in water solution, sonicated, and evaporated. Measurements of the thermophysical properties were performed by DSC analysis, and the dispersion of the nanoparticles was analyzed by SEM microscopy. The results obtained show that the addition of 1.0 wt.% of nanoparticles to the base salt increases the specific heat of about 5–10 % in solid phase and of 6 % in liquid phase. In particular, this research shows that the addition of silica nanoparticles has significant potential for enhancing the thermal storage characteristics of KNO3. The phase-change temperature of potassium nitrate was lowered up to 3 °C, and the latent heat was increased to 12 % with the addition of silica nanoparticles. These results deviated from the predictions of theoretical simple mixing model used. The stored heat as a function of temperature was evaluated for the base salt, and the nanofluids and the maximum values obtained were 229, 234, 242, and 266 J/g respectively. The maximum total gain (16 %) due to the introduction of the nanoparticles (calculated as the ratio between the total stored heat of the nanofluids and the base salt in the range of temperatures 260–390 °C) was also recorded with the introduction of silica. SEM and EDX analysis showed the presence of aggregates in all nanofluids: with silica nanoparticles they were homogenously present while with alumina and silica-alumina also zones with pure salt could be detected.

Climate warming has become an indisputable fact, and wheat is among the most heat-sensitive cereal crops. Heat stress during grain filling threatens global wheat production and food security. Here, we analyzed the physiological and proteomic changes by delayed sowing on the photosynthetic capacity of winter wheat leaves under heat stress. Our aim is to provide a new cultivation way for the heat stress resistance in wheat. Through 2 years field experiment and an open warming simulation system, we compared the changes in wheat grain weight, yield, photosynthetic rate, and chlorophyll fluorescence parameters under heat stress at late grain-filling stage during normal sowing and delayed sowing. At the same time, based on the iTRAQ proteomics, we compared the changes of differentially expressed proteins (DEPs) during the two sowing periods under high temperature stress. In our study, compared with normal sowing, delayed sowing resulted in a significantly higher photosynthetic rate during the grain-filling stage under heat stress, as well as significantly increased grain weight and yield at maturity. The chlorophyll a fluorescence transient (OJIP) analysis showed that delayed sowing significantly reduced the J-step and I-step. Moreover, OJIP parameters, including RC/CSm, TRo/CSm, ETo/CSm, DIo/CSm and ΦPo, ψo, ΦEo, were significantly increased; DIo/CSm and ΦDo, were significantly reduced. GO biological process and KEGG pathway enrichment analyses showed that, among DEPs, proteins involved in photosynthetic electron transport were significantly increased and among photosynthetic metabolic pathways, we have observed upregulated proteins, such as PsbH, PsbR, and PetB. Physiological and proteomic analyses indicate delaying the sowing date of winter wheat reduced heat dissipation by enhancing the scavenging capacity of reactive oxygen species (ROS) in flag leaves, and ensuring energy transmission along the photosynthetic electron transport chain; this increased the distribution ratio of available energy in photochemical reactions and maintained a high photosynthetic system assimilation capacity, which supported a high photosynthetic rate. Hence, delayed sowing may represent a new cultivation strategy for promoting heat stress tolerance in winter wheat.

Phase changing materials (PCMs) microcapsules MPCM32D, consisting of a polymeric melamine-formaldehyde (MF) resin shell surrounding a paraffin core (melting point: 30–32 °C), have been modified by introducing thermally conductive additives on their outer shell surface. As additives, multiwall carbon nanotubes (MWCNTs) and poly (3,4-ethylenedioxyoxythiophene) poly (styrene sulphonate) (PEDOT: PSS) were used in different parts by weight (1 wt.%, 5 wt.%, and 10 wt.%). The main aim of this modification—to enhance the thermal performance of the microencapsulated PCMs intended for textile applications. The morphologic analysis of the newly formed coating of MWCNTs or PEDOT: PSS microcapsules shell was observed by SEM. The heat storage and release capacity were evaluated by changing microcapsules MPCM32D shell modification. In order to evaluate the influence of the modified MF outer shell on the thermal properties of paraffin PCM, a thermal conductivity coefficient (λ) of these unmodified and shell-modified microcapsules was also measured by the comparative method. Based on the identified optimal parameters of the thermal performance of the tested PCM microcapsules, a 3D warp-knitted spacer fabric from PET was treated with a composition containing 5 wt.% MWCNTs or 5 wt.% PEDOT: PSS shell-modified microcapsules MPCM32D and acrylic resin binder. To assess the dynamic thermal behaviour of the treated fabric samples, an IR heating source and IR camera were used. The fabric with 5 wt.% MWCNTs or 5 wt.% PEDOT: PSS in shell-modified paraffin microcapsules MPCM32D revealed much faster heating and significantly slower cooling compared to the fabric treated with the unmodified ones. The thermal conductivity of the investigated fabric samples with modified microcapsules MPCM32D has been improved in comparison to the fabric samples with unmodified ones. That confirms the positive influence of using thermally conductive enhancing additives for the heat transfer rate within the textile sample containing these modified paraffin PCM microcapsules.