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Thermometry techniques have been widely developed during the last decades to analyze thermal properties of various fluid flows. Following the increasing interest for microfluidic applications, most of these techniques have been adapted to the microscale and some new experimental approaches have emerged. In the last years, the need for a detailed experimental analysis of gaseous microflows has drastically grown due to a variety of exciting new applications. Unfortunately, thermometry is not yet well developed for analyzing gas flows at the microscale. Thus, the present review aims at analyzing the main currently available thermometry techniques adapted to microflows. Following a rapid presentation and classification of these techniques, the review is focused on optical techniques, which are the most suited for application at microscale. Their presentation is followed by a discussion about their applicability to gas microflows, especially in confined conditions, and the current challenges to be overcome are presented. A special place is dedicated to Raman and molecular tagging thermometry techniques due to their high potential and low intrusiveness. [ABSTRACT FROM AUTHOR]

This research explores the relationship between the temperatures of the solar corona and planetary magnetosheaths. Based on the second law of thermodynamics, the maximum temperature of the planetary magnetosheaths cannot exceed that of the solar corona. A theoretical investigation is presented into the expansion of the solar corona, the propagation of solar wind, and the compression of planetary magnetosheaths by bow shocks. The method used is general and fits the dynamics of multiple components, thermal anisotropy, and non‐Maxwellian plasmas in the steady state, and approximate formulas are obtained. The results indicate that, for the steady state, planetary magnetosheaths at the subsolar points in the solar system have approach peak mean temperatures. Second, a systematic statistical survey of the average temperature of the planetary magnetosheaths is presented and shows that the average plasma temperature of the subsolar point magnetosheaths of Earth and Saturn are 206 eV (2.39 MK) and 171 eV (1.98 MK), respectively, which are close to that of the corona. The statistical results are consistent with the theoretical estimations. These results are of significant use for estimating the thermal properties of the planetary magnetospheres. Plain Language Summary: This research focuses on the relationship between the temperatures of the planetary magnetosheaths and that of the solar corona. It is thus an interdisciplinary problem in solar‐terrestrial physics. A theoretical investigation is presented on the expansion of the solar corona, the propagation of the solar wind, and the compression of the planetary magnetosheath by bow shocks. An approximate formula for the relationship between the temperatures of the solar corona and that of planetary magnetosheaths is obtained. The quantitative results indicate that the peak temperature of the planetary magnetosheaths are comparable and approach that of the solar corona. A statistical investigation is made of the average temperatures of the magnetosheaths of several planets, and it shows that, although the proton temperatures are several times the electron temperatures, the average plasma temperatures of the magnetosheaths of Earth and Saturn are almost the same as that of the solar corona. This work advances our understanding of the thermal properties of planetary magnetosheaths and also advances research into the formation of plasma sheets. Key Points: A quantitative relationship between the temperature of the steady solar corona and that of the planetary magnetosheaths is shownThe theoretical investigation indicates that planetary subsolar magnetosheaths have approach mean temperaturesA statistical study confirms planetary subsolar magnetosheaths have approach mean temperatures, and these are close to that of the corona [ABSTRACT FROM AUTHOR]

There is a scientific debate whether oxygen concentration may be a factor driving the pattern of size decrease at higher temperature. Central to this debate is the fact that oxygen availability relative to demand for living organisms decreases with increasing temperature. We examined whether rotifers Lecane inermis exposed to hypoxic conditions would evolve smaller sizes than rotifers exposed to normoxic conditions, using experimental evolution with the same fluctuating temperature but differentiated by three regimes of oxygen availability: normoxia, hypoxia throughout the whole thermal range, and hypoxia only at the highest temperature. Immediately after the six-month experiment (more than 90 generations), we tested the plasticity of size responses to temperature in three post-evolution groups, and we related these responses to fitness. The results show that normoxic rotifers had evolved significantly larger sizes than two hypoxic rotifer groups, which were similar in size. All three groups displayed similar plastic body size reductions in response to warming over the range of temperatures they were exposed to during the period of experimental evolution, but they showed different and complex responses at two temperatures below this range. Any type of plastic response to different temperatures resulted in a similar fitness pattern across post-evolution groups. We conclude that (i) these rotifers showed a genetic basis for the pattern of size decrease following evolution under both temperature-dependent and temperature-independent hypoxia; and (ii) plastic body size responds consistently to temperatures that are within the thermal range that the rotifers experienced during their evolutionary history, but responses become more noisy at novel temperatures, suggesting the importance of evolutionary responses to reliable environmental cues. [ABSTRACT FROM AUTHOR]

In this study, a novel fluorine-containing carbon nanosphere was synthesized by high-temperature carbonization of waste fluororubber trimmings, and its mixing method with fluororubber was investigated. It was found that the solution mixing method resulted in the highest tensile strength (7.6 %) and modulus at 100 % strain (13.3 %) of fluororubber compared to the mechanical mixing method. Furthermore, the addition of fluorine-containing carbon nanosphere can significantly enhance fluororubber's heat resistance, inhibit its thermal degradation, and increase its ultimate service temperature (266.3 °C, 2 years). This work provides new insights into the preparation of high-performance fluororubber composites. • A novel fluorine-containing carbon nanosphere is prepared by high-temperature carbonization method. • Fluorine-containing carbon nanosphere can markedly enhance FKM's heat resistance and inhibit its thermal degradation. • SM-FC's tensile strength and modulus at 100 % strain increases by 21.4 % and 105.8 %. • The ultimate use temperature of SM-FC significantly increases to 266.3 °C. • This work offers a new insight of reinforcing fillers preparation. [ABSTRACT FROM AUTHOR]

[Display omitted] • Research on the surface tension of nanofluids was comprehensively summarized. • The effects of nanoparticles, temperature, and surfactants on surface tension were studied. • The impact mechanisms of various factors on surface tension were investigated. • The relationship between the surface tension and wettability was proposed. Nanofluid has become a hot topic in scientific research because of its excellent thermal and physical properties. Surface tension is an important parameter for describing boiling process. Nevertheless, compared with other properties, studies on nanofluids surface tension are still relatively scarce. This paper reviews the research progress on the surface tension of nanofluids, and deeply analyzes the influence mechanisms of various factors for the first time, including the concentration, properties, and size of nanoparticles, the concentration of surfactants, temperature, microwave irradiation, voltage, and stability. Nanoparticles have a complex influence on the surface tension. Comparing existing research results, it is found that hydrophilic nanoparticles tend to increase surface tension in polar solvents, whereas hydrophobic nanoparticles tend to diminish the value of surface tension. Through the study of hybrid nanofluids, it is found that the dominant influence on the surface tension of the fluid is exerted by the higher concentration of nanoparticles. The impact of surfactants and temperature on the surface tension of nanofluids are generally consistent: higher surfactant concentrations or higher temperatures lead to lower surface tension values. In the final part of this review, from the perspective of the correlation between multiple influencing factors and experimental and theoretical methodologies, this article proposes the challenges and future research directions pertaining to the study of nanofluids surface tension. [ABSTRACT FROM AUTHOR]

Carbon nanotubes (CNTs) have attracted much attention from both academia and industry due to their unique mechanical, electrical and thermal properties. Many scholars have been devoted to pursuing its growth mechanism for more than three decades, which is the core of high quality and high yield preparation of CNTs. However, the requirement of exploring its growth mechanism is raised higher, and the combination and cross-use of in situ characterization and machine learning are the key techniques to explore its growth mechanism. The above technologies have important application prospects for the modification and performance enhancement of carbon fiber (CF) on the basis of exploring the growth mechanism of CNTs. And it has been possible to grow CNTs on CF with the trend of industrialization. Therefore, in-depth study of the growth mechanism of CNTs and their enhancement of CF properties is still a key concern and development direction in the future, which has important high-value applications in the manufacture of high-performance products and enhancement of interfacial properties of composite materials. [Display omitted] • The role of machine learning in the study of carbon nanotubes is highlighted. • The importance of catalyst selection and temperature control is emphasized. • The in-situ modification of CNTs to CF was emphasized. [ABSTRACT FROM AUTHOR]

The temperature dependence of the electrical properties of composites formed by biphasic sodium titanate and poly(o-methoxyaniline) (Na2Ti3O7/Na2Ti6O13/POMA) with different concentrations of POMA (0%, 1%, 10%, 15%, 35% and 50%) in the ceramic matrix was determined from measurements of complex impedance. The structural details were studied by means of X-ray diffraction, confirming the formation of the Na2Ti3O7/Na2Ti6O13/POMA composites. The displacement of the (200) reflection from 2θ = 10.45° to 11.15° in the composites with 10 and 15% of POMA suggested the partial replacement of H+ for Na+ in the Na2Ti3O7 structure. The thermal properties were investigated by Thermogravimetry and Differential Thermal Analysis. The Thermogravimetry curves of the composites with POMA content of 1, 10 and 15% presented profiles similar to that of pure sodium titanate sample. The composites with 35 and 50% of POMA showed a process at temperatures around 60–70 °C, which was associated with water absorbed by the polymer. The analysis of the complex impedance spectroscopy measurements revealed that the electrical resistivity of the composites in the range from 0 to 35% increased by two orders of magnitude, with different values for each concentration. This positive temperature coefficient of resistivity was less noticeable in the composite with highest POMA mass content (50%). The rapid increase in resistivity caused an increase in the relaxation time calculated from the time domain. The electrical response of the 50% of POMA compound changes in relation to what was observed in the other compounds, which suggests that there is a saturation limit in the increase in resistivity with POMA content. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Tikrit University for Humanities is the property of Republic of Iraq Ministry of Higher Education & Scientific Research (MOHESR) 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.)

Copyright of Electric Drive is the property of Electric Drive Editorial Office 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.)

Maintenance of adequate thermal properties is critical for correct operation of a gas foil bearing. In this work, the authors present the results of the experimentally conducted thermal characterization of a prototype installation of the bearing. A novel method of temperature identification, based on integrated thermocouples readings, has been employed to determine the thermal properties of the specialized sensing top foil mounted in the tested bearing. Two measurement campaigns have been subsequently completed, applying freely-suspended and two-node support configurations, to gather complementary knowledge regarding the bearing's operation. Apart from the rotational speed and temperature field measurements, the authors have also studied the friction torque and the shaft's journal trajectories based on its radial displacements. The temporal courses for the above-mentioned quantities have enabled inference on the effects present during run-up, run-out and stable state operation at a constant speed. As confirmed, the applied distribution of the integrated sensors allows for temperature readings on the entire outer surface of the foil, and therefore, provides useful data for the bearing characterization. The work is concluded with presentation of the recommended directions regarding future improvements of the proposed measurement technique and more comprehensive study of the bearing's characteristics. [ABSTRACT FROM AUTHOR]

Although KNN‐based ceramics with high electrical properties are obtained through a variety of strategies, the temperature sensitivity is still one of the key technical bottlenecks hindering practical applications. Here, we use a new strategy, meticulously tailoring phase boundary, to refine the ferroelectric boundary of KNN‐based ceramics, leading to high piezoelectricity companied with improving temperature stability. The highest d33 value in this system reaches 501 pC/N with a TC ∼ 240°C, whereas a large strain of ∼0.134% can be kept with 10% lower deterioration until 100°C. The origin of high piezoelectricity is mainly attributed to the well‐preserved multiphase coexistence and the appearance of nanodomains, which greatly facilitate the polarization rotation. Instead of the changed intrinsic thermal insensitivity, the precision phase boundary engineering plays an important role in strengthening the temperature stability of electric‐induced strain. This work provides a simple and effective method to obtain both high electrical properties and excellent thermal stability in KNN‐based ceramics, which is expected to promote the practical applications in the future. [ABSTRACT FROM AUTHOR]

Copyright of Journal of The Iraqi University is the property of Republic of Iraq Ministry of Higher Education & Scientific Research (MOHESR) 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.)

Thermoresponsive self-crimping polybutylene terephtlate (PBT)-based bicomponent fibers were fabricated by melt-spinning to serve as primary constituents for textiles, such as nonwoven battings, for an adaptive single insulting layer. Due to the intrinsically mismatching modulus and coefficient of thermal expansion (CTE), the fibers curl or straighten with temperature, similar to the concept of Timoshenko's bimetallic strip. Maximizing the curvature is driven by an optimum of fiber diameter, overall CTE, and fiber moduli, which are all affected by drawing ratio and, consequently, fiber's microstructure. A draw ratio of 2.33 yielded the best combination of mechanical and thermal properties; it was observed that increasing the draw ratio does not necessarily increase the self-crimping behavior. Tests performed on non-woven battings of these fibers exhibited comparable thermoreponsive behaviors to polypropylene-based thermoresponsive fibers from previous studies in the −20 °C to 20 °C temperature range, which has potential for wearable insulations for both commercial and defense sectors alike. [ABSTRACT FROM AUTHOR]

The current trend towards nanotechnology creates possibilities for its use in materials science as manufacturing material with extraordinary properties, and is one of the goals for scientists in this field. Carbon nanotubes in particular are promising due to their electrical, thermal and mechanical properties, which have been of interest for researchers around the world. This paper focuses on the manufacturing process of the Cu-CNT composite via powder metallurgy and KOBO extrusion process, its further cold drawing process, and electrical resistance test at an elevated temperature. As obtained data proved, the higher the CNT content the lower the electrical resistance. [ABSTRACT FROM AUTHOR]

Polypropylene (PP) is a crystalline thermoplastic widely used in many industrial applications such as medical devices, automotive parts, battery cases, household products, or packaging trays due to its high chemical resistance, processability and impact/stiffness balance, well barrier property, lightness and toughness respectively. However, researchers and engineers have focused on new injection methods to reduce the cost of products and production time. After doing a literature survey about the new injection methods in this study, the co-injection simulation conducted with the Moldex 3-D program using properties of both virgin PP and scrap PP. By the way, the effect of co-injection parameters such as injection pressure, closing force, mod and melt temperatures on co-injection filling characterization investigated. As a result that when the core temperature of the first injected virgin PP is higher than its nucleation temperature, the core of the wall goes on the wall with the second injection of scrap PP until cooling of nucleation temperature. End of co-injection, the second injected scrap PP after first injected virgin PP replaced the advancing virgin PP on the wall core, and a three-layered wall consisting of original PP, scrap PP, original PP obtained. [ABSTRACT FROM AUTHOR]

Herein, we successfully carried out the of CdS nanowires doped with CdSO4 nanoparticles by arc discharge method. For this, two cadmium rods with high purity as anode and cathode electrodes were submerged in a liquid nitrogen medium. The cathode electrode was filled with micro-sized sulfur powder to synthesize CdS nanowires. CdS nanowires were obtained by oxidation using low temperature with CdSO4 nanoparticles. After the arc discharge process, the resultant product was characterized to reveal structural and morphological properties. XRD and electron EDX analyses exposed the coexistence of the CdS and CdSO4 phases. Scanning electron microscopy (SEM) investigations revealed that the synthesized nanostructures formed in a 1D wire nanostructure morphology with a diameter of less than 10 nm and several micrometers in length. Besides, the transmission electron microscopy (TEM) analysis was utilized to monitor the CdSO4 nanoparticles located on CdS nanowires surface. It has been found that the absorption band blue-shifted with 0.53 eV. This blue shift originated from the quantum confinement in the nanoparticles. [ABSTRACT FROM AUTHOR]

The combined process of additive manufacturing (AM) and subsequent hot forming technology enables the low-cost and rapid manufacturing of complicated structures with local features that cannot be manufactured monolithically by traditional forming technologies. The thermal deformation properties of as-deposited materials from AM require investigation. In this paper, laser melting deposition (LMD) was used to prepare as-deposited Ti-6Al-4V samples; high-temperature tensile tests for as-deposited titanium alloy were performed at different strain rates (0.001 s−1, 0.005 s−1, 0.01 s−1) and temperatures (650 °C, 700 °C, 750 °C) using the electrically assisted high-temperature tensile test system. The results show that the material's flow stress level was negatively correlated with temperature and positively correlated with strain rate. EBSD and TEM were used to characterize the microstructure of the samples. The acicular martensite in the original material began to disintegrate under the influence of high-temperature tension, coarsening the lamella and splitting the boundary. The proportion of high-angle grain boundaries after deformation increased significantly from 81.4% to 87.5–90.7%. The results of the micromorphology observations indicate that the micro-deformation mechanism for deposited Ti-6Al-4V samples at high temperatures is mostly discontinuous dynamic recrystallization and dynamic spheroidization. [ABSTRACT FROM AUTHOR]

Medium frequency transformer (MFT) plays a key role in future power systems and new energy systems. It is very important for the safe operation of MFT to correctly calculate the temperature rise and hot spot position. According to the heat dissipation of transformer, the equivalent thermal network model of the core-type transformer is established in this paper. The traditional thermal network model ignores the heat dissipation of the magnetic core column and the inner surface of the yoke to the air. In this paper, the magnetic core column is divided into the air surrounding part and winding surrounding part. The heat dissipation on the inner surface of the yoke is further considered. The improved thermal network model is verified by finite element simulation. The results show that compared with the traditional thermal network model, the improved thermal network model proposed in this paper can more comprehensively analyse the temperature field distribution and calculate the node temperature more accurately. [ABSTRACT FROM AUTHOR]

The nuclear structure and thermal quantities of the superheavy nucleus of 2 9 2 1 2 0 1 7 2 are studied in a recent developed framework of the Finite-Temperature Hartree–Fock–Bogoliubov (FT-HFB) by using a zero-range pairing and including the continuum effects. Analyzing the shell structure of this nucleus at both zero and finite temperature shows a dependence on the various Skyrme-type forces used and a shell closure occurrence at Z = 120 for protons and N = 172 for neutrons with a large gap energy where the pseudo-spin-orbit effects play a primordial role in the shell sequence at finite temperature which confirm the double magicity of 2 9 2 1 2 0 1 7 2 . Thermodynamic quantities are also studied in the same framework where the results are qualitatively similar to what are obtained in case of the hot ordinary nuclei. [ABSTRACT FROM AUTHOR]

The thermal and mechanical effects induced in tissue by ultrasound can be exploited for therapeutic applications. Tissue-mimicking materials (TMMs), reflecting different soft tissue properties, are required for experimental evaluation of therapeutic potential. In the study described here, poly(vinyl alcohol) (PVA) hydrogels were characterized. Hydrogels prepared using different concentrations (5%-20% w/w) and molecular weights of PVA ± cellulose scatterers (2.5%-10% w/w) were characterized acoustically (sound speed, attenuation) as a function of temperature (25°C-45°C), thermally (thermal conductivity, specific heat capacity) and in terms of their cavitation thresholds. Results were compared with measurements in fresh sheep tissue (kidney, liver, spleen). Sound speed depended most strongly on PVA concentration, and attenuation, on cellulose content. For the range of formulations investigated, the PVA gel acoustic properties (sound speed: 1532 ± 17 to 1590 ± 9 m/s, attenuation coefficient: 0.08 ± 0.01 to 0.37 ± 0.02 dB/cm) fell within those measured in fresh tissue. Cavitation thresholds for 10% PVA hydrogels (50% occurrence: 4.1-5.4 MPa, 75% occurrence: 5.4-8.2 MPa) decreased with increasing cellulose content. In summary, PVA cellulose composite hydrogels may be suitable mimics of acoustic, cavitation and thermal properties of soft tissue for a number of therapeutic ultrasound applications. [ABSTRACT FROM AUTHOR]

The ampacity of buried cables is significantly influenced by the thermal properties of the burial environment. When these thermal properties are not homogeneous it is usually necessary to utilize simulations with a relatively high computational cost that may also use commercial software. In this paper an alternative approach is proposed using conformal maps. Temperature is calculated in an annular domain which is a conformal mapping of the half plane space. Circumferential dependence is captured by expanding temperature as a Fourier series, a finite difference solver then determines temperature components radially. The model is as flexible as any two-dimensional slice model of heat transfer through thermal conduction only. Two case studies are considered: three land-based cables in planar configuration and a submarine export cable. The thermal properties of both burial environments are based on conditions which may be encountered in the field and exhibit a high level of stratification. Using a finite element analysis simulation as a benchmark, typical percentage differences in cable ampacities were 0.5%−1%. In addition to accuracy and flexibility the low computational cost of the proposed approach allows for large parameter sweeps, which may be required in a design phase, without requiring commercial software. [ABSTRACT FROM AUTHOR]

Cold protective clothing directly affects outdoor workers' health and work efficiency in winter, and a good performance is particularly needed. This article studies a lightweight smart cold-proof clothing material. Its thermal insulation and heating performance are analyzed theoretically, and its temperature adaptability is obtained, which sheds new light on the design of cold protective clothing. [ABSTRACT FROM AUTHOR]

Hydroxyl-terminated polyether (HTPE) propellant and HTPE/Poly(ε-caprolactone) (PCL) propellant were compared to explore the effects of introducing PCL to HTPE propellant on the mechanical and thermal properties at the wide temperature range of − 50 °C to 70 °C. The energetic properties of HTPE and HTPE/PCL propellants were also evaluated, the ideal specific impulse and density of HTPE/PCL propellant were found to be slightly enhanced comparing with those of HTPE propellant. The tensile mechanical properties results revealed that the introduction of PCL could improve the maximum tensile strength (σm) of HTPE/PCL propellant at the wide temperature range of − 50 °C to 70 °C, its σm increased from 0.38 to 0.75 MPa at 20 °C, 0.25 to 0.48 MPa at 70 °C and 4.01 to 4.77 MPa at − 50 °C separately comparing with those of HTPE propellant. The thermal decomposition behavior at 0.1 MPa showed that the introduction of PCL could promote RDX and AP in HTPE/PCL propellant to decompose. Bu-NENA was hardly to evaporate from HTPE/PCL propellant at higher pressure, which was beneficial to its thermal decomposition. The introduction of PCL could be more effective to inhibit the evaporation of Bu-NENA from HTPE/PCL propellant at 0.1 MPa, the activation energy of evaporation of HTPE and HTPE/PCL propellants was 53.66 kJ mol−1 and 77.90 kJ mol−1, respectively. [ABSTRACT FROM AUTHOR]

Kefiran is a heteropolysaccharide biopolymer usually extracted from kefir grains cultured in cow milk. Due to the lack of information on exopolysaccharides from other types of animal milk, in the present study, cow, buffalo and goat milks were used as raw materials for fermentation. The kefiran extractions from kefir grains were carried out with cold water (method I), hot water (method II) and mild heated water-ultrasound (method III), and then the recovery yield and the physicochemical properties of the kefirans were evaluated to establish the influence of both the extraction conditions and the type of milk. The highest yield was recorded for the cow kefiran using method III (4.79%). The recoveries of goat and buffalo kefirans with methods II and III were similar (2.75–2.81%). Method I had the lowest yields (0.15–0.48%). The physicochemical characteristics were studied with Fourier Transform-Infrared Spectroscopy (FT-IR), Scanning Electron Microscopy (SEM), and Differential Scanning Calorimetry (DSC). Fourier-transform infrared spectroscopy showed the same qualitative profile for all the samples, regardless of the method and the type of milk, confirming that the extraction methods did not affect the chemical structure of the kefirans. Otherwise, the thermal and morphological features of the samples showed differences according to both the type of the milk and the extraction method. The kefiran samples were very thermally stable, having a temperature of degradation (Td) in the range from 264 to 354 °C. The resulting morphological and thermal differences could lead to different practical applications of kefirans in the fields of nutrition and pharmacology. [ABSTRACT FROM AUTHOR]

As a promising environmentally friendly insulating medium, C5F10O needs to be mixed with buffer gases such as technical air to avoid liquefaction. Notably, such a high proportion of oxygen can promote the decomposition of C5F10O and may even eradicate its stability under over-thermal fault. At present, there is still a lack of experimental research investigating the influence of oxygen on the thermal stability of C5F10O, and the mechanism is still unclear. To this end, experiments are carried out on the thermal decomposition properties of C5F10O while mixed with different proportions of O2. And to reveal the mechanism, the dissociation of C5F10O and the reaction of O2 with CF3CO $\cdot $ radical are studied theoretically based on the density functional theory (DFT) and transition state theory (TST). The results signify that oxygen of 4% and above ravages the thermal stability of C5F10O medium, causing it to decompose in a large amount at high temperature, which generates stable products such as CO2, C3F6, C3F8, and C2F6. The mechanism is that O2 is extremely easy to combine with CF3CO $\cdot $ radical to form a complex, which further decomposes, leading to the continuous development of the decomposition of C5F10O. The study revealed the important mechanism of O2 during the decomposition process of C5F10O, providing experimental and theoretical support for the use of C5F10O mixed gas. [ABSTRACT FROM AUTHOR]

The aim of this paper is to investigate the thermal behavior of composite building materials comprised of silt and flax fibers, considering various initial conditions. The experiments were conducted on flax fibers alone, examining factors such as moisture content variation, fibers arrangement, and density. Subsequently, the thermal properties of the earth-flax fiber composite were studied, taking into account the influence of water content and fibers mass content. The thermal properties of both flax fibers and raw earth-flax fibers composite specimens were determined using the experimental unsteady-state method. The results indicate that the thermal conductivity and heat capacity of flax fibers increase with density, temperature, and moisture content. Regardless of fibers density and arrangement of fibers, linear relationships have been established for both thermal conductivity and heat capacity as functions of temperature. Additionally, it was demonstrated that the heat capacity and the thermal conductivity increase with water content, regardless of the percentage of added fibers. Moreover, mixing randomly flax fibers with compacted raw earth material has improved the thermal properties of the composite. This improvement pertains to its insulating capacity, ability to store heat, and, subsequently, its contribution to the thermal comfort provided by such earth composite material when used as a building material. • Thermal conductivity enhances by increasing the moisture content and density. • The arrangements of fibers have highly influenced the thermal properties. • Linear relationships were established for the thermal conductivity and heat capacity. • The addition of flax fibers to raw earth improved the thermal properties. [ABSTRACT FROM AUTHOR]

The quality of a part made by fused filament fabrication substantially depends on the coalescence level achieved between the polymer beads. This paper describes an innovate approach quantifying the influence of the polymer temperature on the coalescence kinetics between two molten polymer beads. The models presented in the literature were modified to introduce two major thermo‐dependents intrinsic characteristics of the polymer, its surface tension and viscosity. The accuracy of the developed model was confirmed by the good correlation between calculated and experimental data. The influence of the polypropylene temperature has been found substantially different for different polymer grades. The results revealed that the change of viscosity influences the coalescence kinetics much more than the surface tension. The developed model is applicable to study the coalescence of any polymer beads in the range of temperatures between the crystallization and degradation temperatures. [ABSTRACT FROM AUTHOR]

We characterized the thermal behavior of a 65 nm bulk CMOS transistor, by measuring the self-heating effect (SHE) as a function of bias condition. We demonstrated that at a base temperature of 6.5 K the channel temperature of the transistor can increase up to several tens of kelvins due to power dissipation. The thermal behavior of the transistor is determined not only by the thermal response of the transistor itself but also by the thermal properties of the surroundings, i.e., source, drain, bulk, and gate interfaces, metal contacts, and vias. On top of it, the thermal response is bias-dependent through bias dependence of power and self-heating. This information becomes relevant for proper design of integrated circuits for quantum computing or other cryogenic applications, where the circuitry requires to be operated at a stable cryogenic temperature. [ABSTRACT FROM AUTHOR]

In this review article, we have investigated the credibility and suitability of the lanthanum gallium silicate (La3Ga5SiO14, LGS) crystals in the application of high-temperature sensing. All the basic properties of the langasite family piezoelectric crystals, such as elastic properties, are taken into consideration and discussed. The crosstalk effects between different vibration modes of LGS crystal are investigated to optimize the crystal cuts. Thereafter, dependences of properties, such as electroelastic properties, resistivity, and electromechanical coupling coefficients of langasite family crystals on higher temperatures, are discussed. Finally, thermal-related properties of langasite family crystals, such as specific heat as well as thermal expansion coefficients, are studied for higher temperature ranges and a comparison with other piezoelectric crystals has also been presented. [ABSTRACT FROM AUTHOR]

The Cold Pool feature of the Middle Atlantic Bight (MAB) is a body of cold bottom water that develops in the spring and persists through the summer‐autumn months. It is maintained by northerly currents and can be traced back to Arctic water masses. The Cold Pool provides habitat for many boreal species at latitudes far south of their normal range and plays an important role in the population dynamics of lower and upper trophic level organisms. Here, we describe changes in the extent and thermal properties of the Cold Pool using both observations and models. Two indices are developed based on a gridded, interpolated bottom temperature dataset; the first is a mean temperature indicator, and the second is a spatial extent indicator. The temperature indicator showed a significant increasing trend over the study period 1968–2019 and a single change point in 2008. Similarly, the area indicator declined significantly, also displaying a change point in 2008. Cold Pool maximum temperature and minimum size were observed in 2017, which is also known as a heatwave year in the MAB. The indices presented here support the view of a rapidly warming Cold Pool that is being limited in its spatial extent. Changes in Cold Pool hydrography will likely affect boreal species distributions and total ecosystem productivity. [ABSTRACT FROM AUTHOR]

The study of flow and convective heat transfer from a rotary sphere in fluid mechanics, astrophysics, and astronaut subjects is important. Today, use of porous media has become widespread because of heat transfer characteristics as well as their lightweight and low volume. Many numerical studies on heat transfer and fluid mechanics in the rotary sphere have been done. The present project studies the phenomena of flow and heat transfer due to the rotation of the sphere at a constant temperature around itself in a porous medium, assuming a laminar, steady and incompressible flow. Analytical solution of the equations used is based on power series and the porosity coefficient is assumed to be between 0 and 1 in this problem. In the spherical coordinate system used here, changes in the azimuthal angle direction are ignored and the body force and pressure gradient for the problem are considered zero. The presence of the porous medium is expected to increase the value of thermal parameters. [ABSTRACT FROM AUTHOR]

The study evaluates the application of pulsed electric field (PEF) and investigates the effects of drying temperature on the thermodynamic and thermal properties of red rice starch (Oryza Sativa L.). The grains underwent extraction process using 0.5% of sodium metabisulfite; the pastes were pretreated with application of PEF (10 and 30 kV/cm); and the pulse frequency was 600 Hz, 6 μs wide, and 90‐s residence time. The pretreated pastes were subjected to temperatures of 40, 50, and 60°C with an air velocity of 1.0 m/s. Evaluation of the thermodynamic properties and thermal properties of the PEF‐pretreated starch was carried out after adjusting the diffusive models using boundary conditions of the first and third types. PEF showed maximum reduction in the time process of 180 min (46.15%) for the PEF 30 kV/cm at a temperature of 60°C. The boundary condition of the third type showed a coefficient of determination (r2) greater than.98 and low values of the χ2 function with diffusivity ranging from 2.159 to 7.877 × 10−5 m2/min. A decrease in activation energy (44.59 kJ/mol) was observed revealing positive and decreasing values. The different intensities of PEF resulted in greater moisture transport presenting a uniform distribution within the starch throughout the drying process. The temperature and gelatinization enthalpy were also influenced by PEF. Therefore, PEF can reduce the costs of the drying and gelatinization process reducing environmental impacts generated by high energy consumption. Practical Applications: The results obtained will contribute to the optimization of industrial production and will serve as a basis for the implementation of a pretreatment of FPE for large‐scale application. This method is promising because it modifies the cellular structure of biological cells such as red rice starch and increases the convective drying rate, reducing drying time and energy expenditure in the process. [ABSTRACT FROM AUTHOR]

Aramid III is a high-performance fiber obtained by bulk structure modification based on the molecular structure of Kevlar fiber. Unlike the intermittent heat treatment method of Armos, Aramid III is prepared by continuous heat treatment technology. In this paper, the effects of heat treatment temperature, tension, and speed on fiber properties are studied by orthogonal experimental design. It is concluded that temperature is the most critical factor affecting fiber tensile strength and elastic modulus. The effects of different heat treatment temperatures on the chemical structure, surface morphology, aggregation structure, and the fiber's mechanical properties and thermal properties are studied. Results show that: the chemical structure of the fiber keeps unchanged and surface morphology of the fibers are similar under the different heat treatment temperatures; the crystallinity of the fiber increases with the increase of temperature; the orientation degree of the fiber increases slightly after heat treatment; with the temperature increasing, the elastic modulus of the fiber increases, the tensile strength and elongation at break increase to a peak and then gradually decrease; the thermal decomposition temperature of the fiber is 533°C, and the decomposition rate is slightly different at different heat treatment temperature. [ABSTRACT FROM AUTHOR]

The thermal properties of NERICA (New Rice for Africa) were investigated on differing moisture content levels and temperatures. The NERICA varieties studied includes FARO 44, FARO 52, FARO 57, FARO 60 and FARO 61. The variety samples were later categorized into two; NERICA Raw-Paddy (FAROs 44, 52, 57, 60 and 61) and NERICA Parboiled-Milled (FAROs 44, 52, 57, 60 and 61) samples. The thermal properties studied were thermal conductivity, specific heat, and thermal diffusivity. The thermal conductivity and the specific heat were determined using the thermal conductivity probe method and a digital scanning calorimeter, respectively. The thermal diffusivity was determined from the obtained results of the specific heat and the thermal conductivity. Results indicated that, increase in moisture content and temperature results to increase in the specific heat, thermal conductivity, and thermal diffusivity of NERICA varieties and these ranged from 4.245 to 39.976 kJ kg--1 oC-1; 0.042 to 1.403 W m-1 oC-1; and 1.236 × 10-5 to 5.933 × 10-5 m² s-1 respectively for NERICA Raw-Paddy and 7.033 to 81.657 kJ kg-1 oC-1; 0.067 to 1.876 W m-1 oC-1; and 1.413 × 10-5 to 5.219 × 10-5 m² s-1 respectively for NERICA Parboiled-Milled. Bulk density decreased with an increase in moisture contents and temperature and the obtained results ranged from 760.3 to 698.7 kg m-3 for NERICA Raw-Paddy and 720.4 to 652.4 kg m-3 for NERICA Parboiled. Regression analyses were carried out on the thermal properties of NERICA varieties and moisture content, and there was positive correlation between the parameters. There were significant effects of moisture content (p<0.05) on all the parameters studied. [ABSTRACT FROM AUTHOR]

The fused filament fabrication (FFF) process of polymer‐based composites has been developed due to its capability to make complex geometries and shapes with reasonable mechanical properties. However, the improvement of mechanical properties of the obtained parts and products are still under study and are interesting for designers. There are several strategies to enhance these desired properties of produced pieces, for example optimizing the process parameters and/or using different architecting designs. This paper presents the effect of some overriding process parameters (liquefier temperature, print speed, layer height, and platform temperature) on the temperature evolution and mechanical behavior of PA6 reinforced with chopped carbon fibers produced by FFF. Due to deposition of multilayers, there is a cyclic profile of temperature in the FFF process, which is a considerable note related to fabrication and consequently the strength of the manufactured parts. In parallel with the study of process parameters effect, this cyclic temperature profile has been measured. The preliminary results related to physicochemical and mechanical properties revealed that differences in crystallinity percentage exist and failure stress/strain can be considered as an indicator to evaluate the mechanical properties of FFF manufactured products. Moreover, measuring the temperature profile of the deposited filaments revealed that process parameters have a considerable influence on the cooling process of deposited filaments which itself affects the bonding of adjacent filaments. The higher temperatures led to slower cooling rate. Finally, the results confirm the impact of mentioned parameters roles on the bonding formation in the FFF process and also the subsequent obtained mechanical properties of the printed parts. Therefore, selection of the optimized and suitable process parameters is an important design consideration. [ABSTRACT FROM AUTHOR]

Of late, atomically thin two-dimensional zinc-sulfide (2D-ZnS) shows great potential for advanced nanodevices and as a substitute to graphene and transition metal di-chalcogenides owing to its exceptional optical and electronic properties. However, the functional performance of nanodevices significantly depends on the effective heat management of the system. In this paper, we explored the thermal transport properties of 2D-ZnS through molecular dynamics simulations. The impact of length, temperature, and vacancy defects on the thermal properties of 2D-ZnS are systematically investigated. We found that the thermal conductivity (TC) rises monotonically with increasing sheet length, and the bulk TC of ∼30.67 W mK−1 is explored for an infinite length ZnS. Beyond room temperature (300 K), the TC differs from the usual 1/T rule and displays an abnormal, slowly declining behavior. The point vacancy (PV) shows the largest decrease in TC compared to the bi vacancy (BV) defects. We calculated phonon modes for various lengths, temperatures, and vacancies to elucidate the TC variation. Conversely, quantum corrections are used to avoid phonon modes' icing effects on the TC at low temperatures. The obtained phonon density of states (PDOS) shows a softening and shrinking nature with increasing temperature, which is responsible for the anomaly in the TC at high temperatures. Owing to the increase of vacancy concentration, the PDOS peaks exhibit a decrease for both types of defects. Moreover, the variation of the specific heat capacity and entropy with BV and PV signify our findings of 2D-ZnS TC at diverse concentrations along with the different forms of vacancies. The results elucidated in this study will be a guide for efficient heat management of ZnS-based optoelectronic and nano-electronic devices. [ABSTRACT FROM AUTHOR]

In this study, total of 60 extracted human teeth were divided into four groups. Group I and II were subjected to LCU A (2550 mW/cm2) and Group III and IV to LCU B (700 mW/cm2), respectively. The increase in temperature level from baseline was recorded using K type thermocouple while curing of dentin bonding agent and composite resins. The temperature rise was significantly higher for Light Curing Unit A which had higher intensity light than Light Curing Unit B. Remaining dentin thickness of the prepared tooth also has significant role in the temperature rise. Hence, light curing units should be used with caution to avoid over‐exposure of teeth. Dental practitioners need to prepare teeth with silicone indices and pre‐assessment of radiographs to avoid over‐preparation. Regular check of intensity of light curing unit using commercially available intensity meter is advocated. [ABSTRACT FROM AUTHOR]

Epoxy resin (EP) insulations are widely considered as potential candidates for various applications. However, it is not suitable for high frequency (HF) and high temperature (HT) applications due to its low thermal conductivity. This research presents the tuning of thermal and electrical properties of EP via resin stoichiometry and incorporation of surface-modified hexagonal boron nitride (h-BN) nanofillers. In this research, the curing agent concentration for pure EP is optimized first based on high thermal stability and sufficiently reliable electrical properties. Second, the optimized pure EP is used as a base material to prepare epoxy/h-BN nanocomposites. Various physicochemical, thermal, and electrical characterizations are performed to analyze the properties of prepared materials. Results show that the higher curing agent concentrations offer a good balance between the thermal and electrical performance of the EP. However, the HF and HT stress exhibits detrimental effects on the breakdown strength and dielectric properties of the materials. Also, the addition of nanofillers further enhances the thermal properties while exhibiting sufficient electrical properties. By the control of resin stoichiometry and nanofiller addition, suitable composites for the HF and HT environment can be realized. [ABSTRACT FROM AUTHOR]

In this paper, a modification method of polypropylene (PP) films is proposed for capacitors by micro doping of carboxylated cellulose nanocrystals (C-CNCs). Results prove that crystallization process of films is promoted, due to the entanglement effect of acicular ultra-structures of C-CNCs on PP molecular chains. With a proper doping content (0.01 wt%), the thermal properties are elevated, and the DC conductivity decreases by raising crystallinity and limiting carrier movement. Modified films possess a restricted dielectric loss at low frequencies because of regular microstructures and decreased conduction loss. Based on DC experiments at different temperatures, the breakdown strength of C-CNC/PP films shows an increase by approximately 51% at 85 °C, basically equaled to the level of pure PP at 25 °C. The mechanism is attributed to deep trap sites, which are introduced by the large crystal region and result in short free path in carrier transport. This novel PP film shows a great potential for application under thermal-electrical compound field in power systems. [ABSTRACT FROM AUTHOR]

The mechanical performance of rock mass subjected to the coupled influences of the elevated temperature and in situ stresses has always been a hot topic in underground rock engineering projects. In this study, a thermal-stress-aperture coupled model was first developed and then incorporated into the particle flow code for the coupled thermomechanical analyses in the fractured rock mass. With thorough considerations of the aperture-dependent thermal and mesomechanical parameters for the fractured rock, the model performed more realistic thermoelastic responses of the fractured rock to the temperatures and confining pressures. Comparative studies between the numerical simulations and previous experimental results indicated that the proposed model was suitable for modeling the thermomechanical behaviors of the fractured rock. Then, a series of numerical compression simulations with heating temperatures of 20°C–600°C and confining pressures of 0–20 MPa were conducted to comprehensively explore the interplay of the temperature and confining pressure on mechanical properties of fractured rock specimens. Finally, the mechanisms that affect the rock thermomechanical properties were further revealed. The results indicated that the compressive strength and elastic modulus increase with an increase in confining pressure for each temperature scenario. The thermal strengthening behavior of rock extrapolated to about 400°C takes place in confined compression tests and is more pronounced at higher confining pressures. The evolutions of thermal properties, microcracks, and mesostructures are the most decisive factors that could induce the variations of rock properties under the coupled temperature and confining pressure treatment. For analyzing the mechanisms behind strengthening and weakening contribution to rock properties, the positive effect of the decrease in average fracture aperture, the dual effects of increased porosity and thermal-induced microcracks, and the negative effect of stress-induced microcracks should be comprehensively considered. [ABSTRACT FROM AUTHOR]

The effects of post-treatment temperature-based methods for accelerating the ageing of PLA were studied on 1D single-PLA filaments after fused filament fabrication (FFF). The goal was to answer the questions whether the PLA can be safely aged—i.e., without degrading—at higher temperatures; at which temperatures, if any; how long it takes for the PLA to fully age at the chosen temperature; and which are the main differences between the material aged at room temperature and the material aged at higher temperatures. We also share other helpful information found. The use of 1D filaments allows for decoupling the variables related to the 3D structure (layer height, raster angle, infill density, and layers adhesion) from the variables solely related to the material (here, we analysed the molecular weight, the molecular orientation, and the crystallinity). 1D PLA filaments were aged at 20, 39, 42, 51, 65, 75, and 80 °C in a water-bath-inspired process in which the hydrolytic degradation of the PLA was minimised for the ageing temperatures of interest. Those temperatures were selected based on a differential scanning calorimetry (DSC) scan of the PLA right after it was printed in order to study the most effective ageing temperature, 39 °C, and highlight possible degradation mechanisms during ageing. The evolution of the thermal and mechanical properties of the PLA filaments at different temperatures was recorded and compared with those of the material aged at room temperature. A DSC scan was used to evaluate the thermal and physical properties, in which the glass transition, enthalpic relaxation, crystallisation, and melting reactions were analysed. A double glass transition was found, and its potential implications for the scientific community are discussed. Tensile tests were performed to evaluate the tensile strength and elastic modulus. The flow-induced molecular orientation, the degradation, the logistic fitting, and the so-called summer effect—the stabilisation of properties at higher values when aged at higher temperatures—are discussed to assess the safety of accelerating the ageing rate and the differences between the materials aged at different temperatures. It was found that the PLA aged at 39 °C (1) reached almost stable properties with just one day of ageing, i.e., the ageing rate accelerated by 875% for the elastic modulus and by 1635% for the yield strength; (2) the stable properties were higher than those from the PLA aged at room temperature; and (3) no signs of degradation were identified for the ageing temperature of interest.

Despite its wide range of real-life applicability, the combined effect of the thermal properties and thickness of a heater on the Leidenfrost temperature (T L) of the system has not been explored. Thus, this study investigates the effects of thermal properties and thickness on the T L using four different metal specimens (Inconel 718, AISI 304 stainless steel, brass, and aluminum). Our experimental results show that the T L decreases with an increase in the thickness of the specimens up to a threshold value. Herein, this varying T L , which varies with thickness, is called transient Leidenfrost temperature (T L,TR) in this study. When the thickness of the sample exceeds the asymptotic thickness, T L became constant, which is termed as the asymptotic Leidenfrost temperature (T L,ASY) in this study. The dependency of the Leidenfrost phenomenon on the thermal properties and thickness can be described by simultaneously considering the heat capacity and heat propagation characteristics; however, in case of the thick specimens, the T L,ASY is mainly considered to be resultant of the speed of heat propagation, including the heat-transfer performance. Consequently, two different trends of the Leidenfrost phenomenon can be predicted. • Leidenfrost temperatures decrease as the thickness of specimens increases to an asymptotic thickness. • Transient Leindenfrost temperature is simultaneously affected by both heat capacity and thermal conductivity. • Asymptotic Leindenfrost temperature is mainly affected by thermal conductivity. • Leidenfrost temperatures are predicted from a transient heat conduction analysis based on the droplet dynamics. [ABSTRACT FROM AUTHOR]

• The thermal cloak in homogeneous isotropic multilayer materials is analyzed. • The influences of the layer's properties in the thermal cloak on the thermal control ability are investigated. • The temperature field of the arbitrary layout composite thermal cloak can be predicted by the deep learning model with almost no time cost. Thermal cloaks can realize thermal manipulation and have been widely applied in the engineering field. Traditional methods, like the finite element method (FEM) and finite difference method, obtain the temperature of the thermal cloak with time-consuming. A deep learning model is proposed to predict the temperature field in homogeneous isotropic multilayer materials. The FEM is applied to solve the thermal cloak and the training data are obtained. The layer's properties, including different layers, thickness, relative thermal conductivities and distribution modes, of the thermal control or manipulative ability for temperature and heat diffusion are also investigated. The deep learning mode is developed by mapping the parameters layout to the temperature field as an image-to-image regression task and the relationship between the layer's properties and the cloaking performances is intelligently established. The temperature field of the arbitrary layout composite can be acquired almost with no time cost. The temperature field with the largest node numbers of medium temperature by the FEM and the deep learning model, is exhibited and compared. Furthermore, we extend the surrogate model to different cases with different boundary conditions, which can still achieve good prediction results. Owing to the high efficiency and complete independence from the mesh densities, the proposed method offers a novel and robust technique for predicting the temperature field and suggestion for the design of the thermal cloak. [ABSTRACT FROM AUTHOR]

Kefiran is a heteropolysaccharide biopolymer usually extracted from kefir grains cultured in cow milk. Due to the lack of information on exopolysaccharides from other types of animal milk, in the present study, cow, buffalo and goat milks were used as raw materials for fermentation. The kefiran extractions from kefir grains were carried out with cold water (method I), hot water (method II) and mild heated water-ultrasound (method III), and then the recovery yield and the physicochemical properties of the kefirans were evaluated to establish the influence of both the extraction conditions and the type of milk. The highest yield was recorded for the cow kefiran using method III (4.79%). The recoveries of goat and buffalo kefirans with methods II and III were similar (2.75–2.81%). Method I had the lowest yields (0.15–0.48%). The physicochemical characteristics were studied with Fourier Transform-Infrared Spectroscopy (FT-IR), Scanning Electron Microscopy (SEM), and Differential Scanning Calorimetry (DSC). Fourier-transform infrared spectroscopy showed the same qualitative profile for all the samples, regardless of the method and the type of milk, confirming that the extraction methods did not affect the chemical structure of the kefirans. Otherwise, the thermal and morphological features of the samples showed differences according to both the type of the milk and the extraction method. The kefiran samples were very thermally stable, having a temperature of degradation (Td) in the range from 264 to 354 °C. The resulting morphological and thermal differences could lead to different practical applications of kefirans in the fields of nutrition and pharmacology.

• Novel Closed-Form Expression: Introduced for precise channel temperature estimation in AlGaN/GaN HEMTs. • Comprehensive Validation: Model's credibility established through rigorous comparisons with DC measurements and TCAD simulations. • Enhanced Accuracy: Outperforms assumptions based on constant thermal conductivity, especially crucial for GaN/Sapphire HEMTs. • Concurrent Optimization: Enables simultaneous enhancement of electrical and thermal properties using standard CAD tools. In this study, we introduced a closed-form empirical expression for estimating the channel temperature in AlGaN/GaN HEMTs. This model incorporates parameters such as substrate thickness, gate length, gate width, and temperature-dependent thermal conductivity. The model's validity was rigorously established through comprehensive comparisons involving the channel temperature measurement procedure (DC) and TCAD device simulations. The outcomes exhibited a noteworthy alignment with the observed model data, reinforcing its credibility. The model yields a notably improved accuracy in channel temperature estimation compared to assumptions based on constant thermal conductivity. This observation holds particular significance for GaN/Sapphire HEMTs. The utilization of the closed-form expression enables the simultaneous optimization of both electrical and thermal properties, utilizing conventional computer-aided design tools. [ABSTRACT FROM AUTHOR]

We investigated the thermal transport properties of Cu 1- x Ag x Ir 2 S 4 (0 ≤ x ≤ 0.05). The thermal conductivity of CuIr 2 S 4 exhibits a sudden change at the metal-insulator transition (MIT) temperature, where the phonon thermal conductivity κ ph decreases sharply from the insulating phase (IP) to the metallic phase (MP). The decrease in κ ph is attributed to a decrease in the phonon mean free path l from the IP to the MP, which is caused by anomalous phonon scattering in the MP. The decrease in l at the MIT temperature becomes less pronounced with increasing x, and the absolute values of l in the MP for x = 0.025 and 0.05 are higher than that for x = 0. This behavior suggests that the anomalous phonon scattering is suppressed by Ag substitution. Compared with previously reported results for the effect of Zn substitutions at Cu sites, the phonon relaxation time exhibits a distinct behavior for Ag and Zn substitution. [ABSTRACT FROM AUTHOR]

Thermal, thermo-mechanical and mechanical properties of four different commercially available polyetheretherketones (PEEK) based materials were investigated. PEEK matrix was either modified and/or reinforced with carbon fibres, graphite and/or PTFE. Impact strength was measured at three different temperatures: 25 °C, −100 °C, and −195 °C. At 25 °C, thermal stability and mechanical properties, including the elastic modulus, compression, and impact strength, were enhanced with the addition of carbon fibres. Matrix modification had a minor impact on thermal stability, while the mechanical properties decreased, except for impact strength. At −100 °C, the mechanical properties of the neat polymers were improved, including increased impact strength by 20% compared to values at 25 °C. Addition of fillers hindered the rise of impact strength due to complex mechanisms caused by different coefficients of thermal expansion of reinforcements and matrix. At −195 °C, the significant increase of impact strength was revealed for unmodified PEEK reaching 30 times higher values than at 25 °C, while matrix modification suppressed the rise of impact strength. The scratch test indicated the superior behaviour of unfilled PEEK during the tested load range (up to 15 N), while the effect of the fillers was observed at much lower load threshold of 7 N. • Cryogenic temperatures have a significant impact on mechanical properties. • Self-toughening mechanisms at cryogenic temperatures retained by matrix modification. • Difference of filler/matrix CTEs affects impact strength at cryogenic temperatures. • Scratch resistance is governed by fillers until a load threshold reached. [ABSTRACT FROM AUTHOR]