High Temperature Research Articles

Single‐atom Barium Promoter Enormously Enhanced Non‐noble Metal Catalyst for Ammonia Decomposition

As a well‐established topic, single‐atom catalyst has drawn growing interest for its high utilization of metal. However, researchers prefer to develop various active metals with single‐atom form, the intrinsic roles of single‐atom promoters are usually underrated, which are significant in boosting reaction activity. In this work, Ba single atoms were in situ prepared in the Co‐Ba/Y2O3 catalyst with crystallized BaCO3 as the precursor under the ammonia decomposition reaction condition. The optimized Co‐Ba/Y2O3 catalyst achieves extremely high H2 production rate of 138.3 mmolH2·gcat−1·min−1 at very low temperature (500 °C, GHSV = 840,000 mL·g−1·h−1) and Co‐Ba/Y2O3 exhibits excellent durability during the 350 h test, which realizes the highest activity among all non‐noble catalysts, and reaches or even exceeds numerous reported Ru‐based catalysts. Both Y2O3 and Co demonstrate positive interactions with Ba, which significantly facilitates the dispersion of Ba species at high temperatures (≥ 600 °C). Ba single atoms significantly enhance the charge density of Co and form additionally active Co‐O‐Ba‐Y2O3 interfacial sites, which alleviates hydrogen poisoning and decreases the reaction barrier of the N‐H bond activation of *NH. The exploration of atomically dispersed promoters is groundbreaking in heterogeneous catalysis, which opens up a whole new domain of catalytic material.

First‐Principles Study of Structural and Elastic, Electronic, and Thermoelectric Properties of PdSe2

The thermoelectric material in orthorhombic (Pbca) phase is studied with the help of density functional theory implemented in WIEN2k. The main properties of investigated are elastic, electronic, and thermoelectric properties. The anisotropy factors obtained with the elastic constants indicate that is strongly anisotropic. The Tran and Blaha‐modified Becke–Johnson exchange potential is used for bandgap calculations. The BoltzTraP code is used to find out the thermoelectric properties of . At 300 K, the maximum value of the Seebeck coefficient is 200 μV K−1 for the hole carrier concentration of 2.5 × 1019 cm−3 and is 241 μV K−1 for the electron carrier concentration of 1.2 × 1019 cm−3. The power factor (PF) and figure of merit (ZT) are calculated for different carrier concentrations and temperatures. The optimum value of ZT for bulk PdSe2 as calculated in this work is ≈0.6 for hole carrier concentration (p = 2.6 × 1020 cm−3) at 800 K, which suggests as a potential material in thermoelectric applications at higher temperatures.

Molecular Dynamics and Self-Assembly in Double Hydrophilic Block and Random Copolymers.

We investigate the self-assembly and dynamics of double hydrophilic block copolymers (DHBCs) composed of densely grafted poly[oligo(ethylene glycol) methacrylate] (POEGMA) and poly(vinyl benzyl trimethylammonium chloride) (PVBTMAC) parent blocks by means of calorimetry, small- and wide-angle X-ray scattering (SAXS/WAXS), and dielectric spectroscopy. A weak segregation strength is evident from X-ray measurements, implying a disordered state and reflecting the inherent miscibility between the host homopolymers. The presence of intermixed POEGMA/PVBTMAC nanodomains results in homogeneous molecular dynamics, as evidenced through isothermal dielectric and temperature-modulated DSC measurements. The intermixed process undergoes a glass transition at a temperature approximately 40 K higher than the vitrification of bulk POEGMA segments, and it shifts to an even higher temperature by increasing the content of the hard block. At temperatures below the intermixed glass transition temperature, the confined POEGMA segments between the glassy intermixed regions contribute to a segmental process featuring (i) reduced glass transition temperature (Tg), (ii) reduced dielectric strength, (iii) broader distribution of relaxation times, and (iv) reduced fragility compared to the POEGMA homopolymer. We also observe two glass transition temperatures of dry PVBTMAC, which we attribute to the backbone and side chain segmental relaxation. To the best of our knowledge, this is the first time in the literature that these glass transitions of dry PVBTMAC have been reported. Finally, this study shows that excellent mixing of the two homopolymers is obtained, and this implies that different properties of this copolymer system can be tailored by adjusting the concentration of each homopolymer.

Inertia in transformed times: Work health and safety amid climate change

Climate change will impact work health and safety conditions at an unprecedented scale, and the effects are already being felt. The most significant consequences are for workers labouring in higher temperatures and heatwaves. Other dangers include increased air pollution, vector-borne diseases and solar ultraviolet radiation. The International Labour Organisation (ILO) says climate change and WHS ‘needs to top our list of global priorities’, requiring national planning and action to ensure successful workplace adaptation to limit injuries and deaths. If this is correct, why is so little happening in Australia to plan for these current and emerging issues? This article considers the findings of key ILO and Australian Government reports and initiatives in 2023 and 2024 to assess what action experts argue is needed and how Australia stacks up.

Tailoring the Properties of Chemically Recyclable Polyethylene-Like Multiblock Polymers by Modulating the Branch Structure.

Developing plastics that fill the need of polyolefins yet are more easily recyclable is a critical need to address the plastic waste crisis. However, most efforts in this vein have focused on high-density polyethylene (PE), while many different types of PE exist. To create broadly sustainable PE with modular properties, we present the synthesis, characterization, and demonstration of materials applications for chemically recyclable PE-like multiblock polymers prepared from distinct hard and soft blocks using ruthenium-catalyzed dehydrogenative polymerization. By altering the branching pattern within the soft blocks, a series of PE-like multiblock polymers were synthesized with tunable glass transition temperatures (Tg) while maintaining consistent high melting temperatures (Tm). A clear U-shape trend between Tg and mechanical properties was found, showcasing their potential as sustainable materials with tailored properties spanning commercial linear low-density polyethylene (LLDPE) and low-density polyethylene (LDPE). These materials offer adjustable adhesive strength to metal and demonstrate chemical recyclability and selective depolymerization in mixed plastic streams, promoting circularity and separation.

Diverse reactivity of maleimides in polymer science and beyond

AbstractMaleimides are remarkably versatile functional groups, capable of participating in homo‐ and copolymerizations, Diels–Alder and (photo)cycloadditions, Michael additions, and other reactions. Their reactivity has afforded materials ranging from polyimides with high upper service temperatures to hydrogels for regenerative medicine applications. Moreover, maleimides have proven to be an enabling chemistry for pharmaceutical development and bioconjugation via straightforward modification of cysteine residues. To exert spatiotemporal control over reactions with maleimides, multiple approaches have been developed to photocage nucleophiles, dienes, and dipoles. Additionally, further substitution of the maleimide alkene (e.g. monohalo‐, dihalo‐, thio‐, amino‐ and methyl‐maleimides, among other substituents) confers tunable reactivity and dynamicity, as well as responsive mechanical and optical properties. In this mini‐review, we highlight the diverse functionality of maleimides, underscoring their notable impact in polymer science. This moiety and related heterocycles will play an important role in future innovations in chemistry, biomedical, and materials research. © 2024 The Author(s). Polymer International published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

The Efficacy of Nutritional Strategies and Ergogenic Aids on Acute Responses and Chronic Adaptations to Exertional-Heat Exposure: A Narrative Review

Global warming is attributed to an increased frequency of high ambient temperatures and humidity, elevating the prevalence of high-temperature-related illness and death. Evidence over recent decades highlights that tailored nutritional strategies are essential to improve performance and optimise health during acute and chronic exertional-heat exposure. Therefore, the purpose of this review is to discuss the efficacy of various nutritional strategies and ergogenic aids on responses during and following acute and chronic exertional-heat exposure. An outline is provided surrounding the application of various nutritional practices (e.g., carbohydrate loading, fluid replacement strategies) and ergogenic aids (e.g., caffeine, creatine, nitrate, tyrosine) to improve physiological, cognitive, and recovery responses to acute exertional-heat exposure. Additionally, this review will evaluate if the magnitude and time course of chronic heat adaptations can be modified with tailored supplementation practices. This review highlights that there is robust evidence for the use of certain ergogenic aids and nutritional strategies to improve performance and health outcomes during exertional-heat exposure. However, equivocal findings across studies appear dependent on factors such as exercise testing modality, duration, and intensity; outcome measures in relation to the ergogenic aid’s proposed mechanism of action; and sex-specific responses. Collectively, this review provides evidence-based recommendations and highlights areas for future research that have the potential to assist with prescribing specific nutritional strategies and ergogenic aids in populations frequently exercising in the heat. Future research is required to establish dose-, sex-, and exercise-modality-specific responses to various nutritional practices and ergogenic aid use for acute and chronic exertional-heat exposure.

A systematic review and meta-analysis of heat exposure impacts on maternal, fetal and neonatal health.

Climate Change has severe and wide-ranging health impacts, especially for vulnerable groups. Despite growing evidence of heat-associated adverse maternal and neonatal health outcomes, there remains a lack of synthesis quantifying associations and identifying specific risk periods. We systematically reviewed the literature on heat impacts on maternal, fetal, and neonatal health, and quantified impacts through meta-analyses. We found 198 studies across66 countries, predominantly high income (63.3%) and temperature climate zones (40.1%), and 23 outcomes. Results showed increased odds of preterm birth of 1.04 (95%CI = 1.03, 1.06; n = 12) per 1°C increase in heat exposure and 1.26 (95%CI = 1.08, 1.47; n = 10) during heatwaves. Similarly high heat exposure increased the risk for stillbirths (OR = 1.13 (95%CI=0.95, 1.34; n = 9)), congenital anomalies (OR=1.48 (95%CI = 1.16, 1.88; n = 6)), and gestational diabetes mellitus (OR = 1.28 (95%CI = 1.05, 1.74; n = 4)). The odds of any obstetric complication increased by 1.25 (95%CI = 1.09, 1.42; n = 11) during heatwaves. Patterns in susceptibility windows varied by condition. The findings were limited by heterogeneity in exposure metrics and study designs. The systematic review demonstrated that escalating heat exposure poses a major threat to maternal and neonatal health, highlighting research priorities, guiding the selection and monitoring of heat-health indicators, and emphasising the need to prioritise maternal and neonatal health in national climate-health programmes.

Non-fatal Injury burden attributed to night-time temperature during 1990s-2010s in China

The night-time temperature-related injury risks and burdens were unclear. Using 11,512,467 non-fatal injury cases in 243 surveillance hospitals across China from 2006-2021, we estimated the associations between daytime or night-time temperature and injury by a time-stratified case-crossover study, and compared their injury burden during 1990s–2010s. We found the excess risk (ER) for per 1°C rise in night-time temperature (ER = 1.21%, 95%CI:1.03%,1.39%) was greater than that in daytime (ER = 0.86%, 95%CI:0.72%,1.00%). Compared with the 1980s, the attributable fractions (AFs) for daytime and night-time temperature change during the 1990s–2010s were 0.59% (95%eCI:0.54%,0.67%) and 0.73% (95%eCI:0.69%,0.77%), respectively. Spatially, the higher AFs of night-time temperature were more widely distributed than daytime temperature. The non-fatal injury risk attributed to night-time temperature was stronger than daytime temperature, and increased night-time temperatures posed a heavier injury burden compared with daytime temperature in China. Our findings indicate that high night-time temperature is an important injury risk in the context of climate change.

Experimental Study on Cryogenic Compressed Hydrogen Jet Flames

Cryogenic compressed hydrogen (CcH2) technology combines the advantages of high pressure and low temperature to achieve high hydrogen storage density without liquefying the hydrogen, which has broad application prospects. However, the safety concerns related to cryogenic hydrogen need to be carefully addressed beforehand. In the present work, cryogenic hydrogen jet flames are experimentally investigated for various release pressures and initial temperatures. The flame length and thermal radiation flux were measured for horizontally releasing with nozzle diameters of 0.5–2 mm, temperatures ranging from 93 to 298 K, and initial pressures of 2–10 MPa. The results show that the flame length is dependent on the nozzle diameter, stagnation pressure and temperature. At a given pressure, the flame length, size and total radiant power increase with decreasing temperature, which is attributed to the lower jet flow velocity and higher density of low-temperature hydrogen. The normalized flame length Lf/D is correlated with the pressure ratio and temperature ratio. The correlation can be used to predict the flame length at various hydrogen pressures and temperatures. The normalized flame length of the cryogenic hydrogen jet flame is greater than that of the room-temperature hydrogen jet flame. The radiative heat flux of the flame can be predicted by the mass flow rate of the jet flow.

Microstructure instability of additively manufactured alloy 718 fabricated by laser powder bed fusion during thermal exposure at 600–1000 ℃

Microstructure and precipitation behavior of alloy 718 produced by laser powder bed fusion (L-PBF) and its recrystallized counterpart were evaluated after thermal exposure at a temperature range of 600–1000 ℃ for up to 1000 h. The as-built 718 featured a microstructure of columnar grains, and dislocation cell structures (DCSs) with chemical segregations (rich in Nb, Ti, Mo and depleted in Cr, Fe) and precipitates (Laves phase and carbonitride). The DCSs remained thermally stable for up to 1000 h at 600 ℃ or 100 h at 700 ℃, but only 10 h at 800 ℃. With the temperature increasing to 900 ℃ and 1000 ℃ for 1 h duration, the DCSs tended to partially disassemble, and the chemical segregations were removed. The chemical segregations at cell boundaries of the as-built 718 promoted the formation of γ′, γ″ and δ phases during aging, leading to a spatially heterogeneous distribution of γ′ and γ″ phases between the cell boundaries and interiors during short exposure time or at lower temperatures. Meanwhile, the coarsening of γ′ and γ″ phases and the phase transformation of γ″ to δ at 700–800 ℃ were facilitated in the as-built 718 compared to the recrystallized ones. A unique precipitation distribution was observed at 700 ℃ that γ′ and γ″ phases precipitated both at the cell boundaries and within cell interiors, while only γ′ formed in the vicinity of cell boundaries. Time-temperature-transformation curves for additively manufactured and recrystallized 718 were constructed based on the microstructure analyses. This study indicates that conventional heat treatment procedures may be suboptimized for additively manufactured 718 in high temperature applications.

Component analysis of a 25-cell stack following 6.7 kh of high temperature electrolysis

The demonstration of relevant lifetimes for solid oxide electrolysis stacks is an underlying necessity to the rapidly industrializing technology. Following a 6.7 kh test of a 25-cell stack, post-mortem analyses of cells, seals, and interconnects were carried out to assess their long-term stability.Micrographs of cells aged in nominal conditions highlighted Ni depletion in the functional layer, SZO interlayer growth, and the presence of a Sr-rich secondary phase. The microstructure of glass-ceramic seals remained for the most part stable following operation. In addition, in spite of a thin design and the absence of coating, interconnects showed remarkable stability, with limited chromia growth and Cr depletion. Notably, no Cr poisoning could be detected in the cell functional layer.In view of the results, the loss of tightness of the H2 compartment, due to initial defects or caused by failures, is seen as the most immediate threat to this stack long-term operation.

Room-temperature selective cyclodehydrogenation on Au(111) via radical addition of open-shell resonance structures

Cyclodehydrogenation is an important ring-formation reaction that can directly produce planar-conjugated carbon-based nanomaterials from nonplanar molecules. However, inherently high C–H bond energy necessitates a high temperature during dehydrogenation, and the ubiquity of C − H bonds in molecules and small differences in their bond energies hinder the selectivity of dehydrogenation. Here, we report a room-temperature cyclodehydrogenation reaction on Au(111) via radical addition of open-shell resonance structures and demonstrate that radical addition significantly decreases cyclodehydrogenation temperature and further improves the chemoselectivity of dehydrogenation. Using scanning tunneling microscopy and non-contact atomic force microscopy, we visualize the cascade reaction process involved in cyclodehydrogenation and determine atomic structures and molecular orbitals of the planar acetylene-linked oxa-nanographene products. The nonplanar intermediates observed during progression annealing, combined with density functional theory calculations, suggest that room-temperature cyclodehydrogenation involves the formation of transient radicals, intramolecular radical addition, and hydrogen elimination; and that the high chemoselectivity of cyclodehydrogenation arises from the reversibility and different thermodynamics of radical addition step.

Helping the Most Vulnerable Stay Cool in Extreme Heat

Choosing the ideal location for air-conditioned cooling centers in cities facing dangerously high temperatures takes good population data and community engagement.

Nanoarchitecture via Synchronic Stacking of Metallic and Nonmetallic Two-Dimensional Nanosheets for Optimal Light-Driven Ion Transport.

The exceptional selectivity and responsive ion transport in biological channels inspire technology breakthrough in energy, environmental, and resource sectors. However, existing nanofluidic systems with a high photothermal conversion efficiency often exhibit excessive thermal conductivity, which impedes the creation of effective temperature gradients and results in a low ion transport efficiency. In this study, a strategy based on the synchronic stacking of metallic and nonmetallic two-dimensional (2D) nanosheets was presented to construct heterogeneous nanofluidic channels. This specific nanoconfined architecture sustained high temperatures in the illuminated area while maintaining low temperatures in the nonilluminated area, thus obtaining a robust driving force from sunlight for directional ion transport. As a result, our light-responsive ion transport system demonstrated significant potential in solar energy conversion and osmotic energy harvesting, surpassing those of all previously reported nanofluidic systems. Additionally, although it is still at the proof-of-concept stage, it shows great promise in light signal monitoring. This work provides an effective strategy for developing advanced light-responsive ion transport systems and their important applications.

Exploration of graphitic carbon from crude oil vacuum residue

Preparation of graphitic carbon from low value refinery waste has captivated immense interest in past years owing to its low cost and abundant nature. Successful utilization of petroleum vacuum residue is a major challenge in the petroleum industry. In this study pyrolysis of vacuum residue fractions has been carried out for the preparation of graphitic carbon like material. The vacuum residue fractions were obtained from three different crude oils originated from Middle East, Canada and South America. The purity of the Aromatic, Resin and Asphaltene (ARA) fractions were confirmed using TLC-FID which denoted complete separation. The chemical composition were determined using elemental analysis and it revealed ARA fractions to be carbon rich regardless of its origin. Further, sulphur content was found to be high in ARA fractions from Heavy Crude oil (HCO). The degree of polymerization and molecular weight measured using GPC specify that asphaltene has high accumulation with high molecular weight compared with aromatic and resins. ARA derived carbon and heat-treated materials were analysed by TGA, XRD and Raman spectroscopy to study microstructural changes in formation of graphite like material. Thermogravimetric analysis of all ARA samples revealed the different decomposition stages for pyrolyzed, calcined and graphitized samples. The results of XRD demonstrated that the distance between the planes (d-spacing) is above 3.35 Å for all high temperature treated ARA derived carbon materials irrespective of its origin, indicating formation of graphite like structure. In Raman analysis, the nature and intensity of G and D bands evolution during each step of pyrolysis is supporting XRD results for formation of highly ordered graphitic carbon material. Furthermore, understanding feed quality has direct influence on high efficiency, low costs and sustainability, the major issues for oil refinery business.

Ultra-broadband absorber and perfect thermal emitter for high-efficiency solar energy absorption and conversion

This study proposes a pyramid-shaped solar absorber designed with multi-layered Ti-SiO2 ring stacked. The structure achieves an average absorption efficiency of 98.03 % over the range of 280–4000 nm, and under AM1.5 spectral conditions, the weighted average absorption efficiency reaches 97.66 %, the bandwidth with an absorption efficiency greater than 90 % reaches 3750 nm. To explore the reason for achieving ultra-broadband absorption with this structure, the electromagnetic field distribution at three absorption peaks was calculated. The results revealed that the resonance between the polarization direction of the three-layer circular ring stacked structure and the plasmon resonance at the junction of Ti and SiO2 contribute to the model's capability for ultra-broadband high-efficiency absorption. At the same time, the thermal emissivity of the structure was calculated at high temperatures of 1000 K and 2000 K, both exceeding 97 %. Furthermore, due to the fully symmetrical design, the absorber is polarization-independent. It was found through calculations that whether in TM mode or TE mode, as the incident angle varies from 0° to 60°, the average absorption efficiency of the absorber changes only by 11.16 %, thereby verifying the structure's excellent insensitivity to incident light angles. In summary, all these characteristics indicate that the model has excellent application prospects in fields such as solar energy collection and photothermal conversion.

Improving thermal conductivity of phthalonitrile composite through constructing three-dimensional graphene networks and interfacial engineering

Achieving high thermal conductivity for polymer composite with low filler loading is still a challenge. Here, phthalonitrile (APN)/few-layer graphene (FLG) composite with high thermal conductivity was successfully prepared by constructing three dimensional (3D) thermally conductive pathways. Such 3D structure was formed by hot compressing APN@FLG core-shell structures. The results showed that the thermal conductivity of APN@FLG composites with only 30 wt% of FLG was up to 11.4Wm−1K−1, which was 57 times to that of the pristine resin (0.2 Wm−1K−1). Such high thermal conductivity was attributed to the 3D connected thermally conductive networks. Furthermore, benefited from the high thermal stability of APN matrix, the as-prepared composite also showed high T5 (temperature of mass losing 5 %) of higher than 500 °C. The composite with both high thermal conductivity and heat resistance are expected to be an idea candidate for high temperature thermal management applications.

PlFabG improves high-temperature resistance in herbaceous peony by increasing saturated fatty acids

The herbaceous peony (Paeonia lactiflora Pall.) is renowned for its striking flowers, which are highly valued in the cut flower industry. However, in the middle and lower reaches of the Yangtze River, the elevated summer temperatures negatively affect the plant's flowering capacity in the subsequent year. 3-oxoacyl-ACP reductase (FabG) is a component of the type II fatty acid synthesis (FAS II) system, where it plays a role in facilitating the production of saturated fatty acids. However, its role in conferring resistance to high-temperature stress remains unclear. In order to investigate the function of PlFabG in dealing with high-temperature stress, we isolated PlFabG from P. lactiflora. The gene contains an open reading frame (ORF) of 780 bp, which encodes 259 amino acids. Quantitative real-time PCR (qRT-PCR) analysis showed that the expression levels of PlFabG increased with prolonged exposure to high temperature. Additionally, plants overexpressing PlFabG maintained a relatively healthy phenotype under high-temperature stress, whereas plants with silencing PlFabG exhibited more severe leaf scorching and wilting under the same conditions. Various physiological indices indicated that PlFabG reduced reactive oxygen species (ROS) accumulation and enhanced the saturation of photosystem II. Most importantly, PlFabG helped P. lactiflora withstand high-temperature stress by increasing the proportion of saturated fatty acids, thereby maintaining cell membrane integrity. These findings elucidate the beneficial role of PlFabG in enhancing plant tolerance to high temperature and provide a strong theoretical support for the development of high-temperature tolerance in transgenic P. lactiflora.

A Numerical Simulation of the Effect of Drilling Fluid Rheology on Cutting Migration in Horizontal Wells at Different Drilling Fluid Temperatures

In recent years, significant breakthroughs have been made in the exploration of deep to ultra-deep oil and gas reserves onshore in China. These conventional deep to ultra-deep reservoirs are typically buried at depths exceeding 4500 m, with bottom-hole temperatures surpassing 150 °C. The high temperatures at the bottom of the well are more likely to cause deterioration in drilling fluid properties, altering its rheological properties and reducing cutting transport efficiency, which can lead to wellbore cleaning issues. In this paper, the numerical simulation method is used to analyze the influence of cutting particle size, drilling fluid flow rate, drill pipe rotation speed, and drill pipe eccentricity on the annular cutting concentration under different wellbore drilling fluid temperature conditions. The results show that at the same cutting particle size, as the drilling fluid temperature increases, the cutting concentration in the annulus increases sharply. The increase is the largest when the particle size is 3 mm, and when the drilling fluid temperature is 220 °C, the cutting concentration increases by 79.7% compared to at 200 °C and by 279% compared to at 180 °C. When the flow rate increases from 0.5 m/s to 1.0 m/s, the annular cutting concentration at drilling fluid temperatures of 220 °C and 200 °C decreases by 70.5% and 50.4%, respectively. The higher the drilling fluid temperature, the better the cutting removal effect when increasing the drill pipe rotation speed. However, when the rotation speed exceeds 120 rpm, the change in cutting concentration with increasing rotation speed becomes insignificant. When the drill pipe eccentricity is small, an increase in drilling fluid temperature leads to a significant rise in annular cutting concentration. However, when the drill pipe eccentricity is large, changes in drilling fluid temperature have a smaller impact on cutting concentration. The research findings can provide engineering guidance and theoretical support for the design of drilling fluid hydraulic parameters for cutting transport and rheological parameters in high-temperature wellbores.