High Temperature Research Articles

Design and Analysis of an Integrated Additively Manufactured Test Article for Plasma-Facing Components

Current plasma-facing components (PFCs) used in helium-cooled divertor modules are complex structures with tungsten tile, steel sleeve components, and cartridges, all assembled in a helium-cooled multiple jet (HEMJ) structure. The goal of this project is to simplify the complex PFC design using additive manufacturing techniques to create a single integrated tungsten test article. Apart from the flexibility this opens up in exploring a wide array of geometries for the article, having a single integrated article significantly reduces the number of joints and parts in the article, thus reducing chances of leaks. A process called electron beam melting has shown to produce very high-density samples and unique geometries, enabling HEMJ or similar designs. To validate and optimize this novel design, the model underwent a series of computational fluid dynamics and finite element analysis simulations to replicate steady-state heat flux in the divertors. The simulations presented in this study consider a steady-state base heat flux of 5 MW/m2, with water serving as the coolant. Future research will explore the use of helium as a coolant, simulate edge-localized-mode conditions, and include experimental validation. Since 3D-printed tungsten is anisotropic, the build direction versus build plane of the article are taken into consideration for the test article strength. Because of the high operating temperatures and low ductility of tungsten, thermal creep and brittle fracture are important failure mechanisms to consider. The cap is evaluated with various flow velocities and nozzle diameters, and an optimal design choice is made for which this cap will survive the divertor conditions with a conservative safety margin.

Doping-Free Carbon-Nanotube Transistors as Wide-Temperature-Range Devices.

With the development of fields such as lunar exploration and automotive technology, the importance of devices suitable for wide-temperature range is increasingly highlighted. Chemically doped devices, represented by silicon, hardly meet wide-temperature-range requirements, as impurities affect transistor operation at both low and high temperatures. Carbon nanotube (CNT) transistors have high- and low-temperature advantages due to their doping-free structure. In this study, we investigated operation in the temperature range of 10 to 473 K of both n- and p-type field-effect transistors based on network carbon nanotube thin film, complementing the research in wide-temperature-range transport characteristics of CNT transistors, and explored the mechanism of the devices. Experimental results demonstrate that compared to other structures, at high temperature, doping-free carbon nanotube field-effect transistors exhibit no intrinsic excitation induced device leakage, maintaining an on-off ratio of over 103 even at 473 K. At low temperature, no carrier freeze-out issues are observed, resulting in a more stable threshold voltage. Those results explore the advantage of the doping-free device in the wide-temperature range scenario, being free from dopant that can affect performance at extreme temperatures, revealing the great potential of carbon-based devices for wide-temperature-range applications.

CRISPR/Cas9-based modulation of V-PPase expression in rice improves grain quality and yield under high nighttime temperature

Key messageTranscriptional modulation of the vacuolar H+ translocating pyrophosphatase expressed specifically in the endosperm and reproductive tissue of rice improves its spikelet fertility and reduces grain chalkiness under high nighttime temperature.

Fabrication and Characterizations of Porous AlGaN Distributed Bragg Reflectors with Excellent Thermal Stability at High Temperature

Fabrication and Characterizations of Porous AlGaN Distributed Bragg Reflectors with Excellent Thermal Stability at High Temperature

Resistance mechanism of Abies beshanzuensis under heat stress was elucidated through the integration of physiological and transcriptomic analyses

Elevated temperatures significantly impaired the normal growth and development of plants. This study combined physiological and transcriptomic analyses to explore the potential mechanisms of response to heat stress in Abies beshanzuensis M. H. Wu. Under heat stress, A. beshanzuensis exhibited reduced photosynthetic rates and chlorophyll content, accompanied by marked downregulation of photosynthesis-associated genes, suggesting heat-induced photoinhibition and compromised carbon assimilation capacity. Furthermore, the increased activities of MDA, SOD, POD, and CAT suggested that A. beshanzuensis could withstand heat stress by enhancing the activity of antioxidant enzymes to mitigate excess reactive oxygen species and anions. Transcriptome analysis revealed the induction of genes related to heat shock proteins, plant hormone signaling, and antioxidants, which could enhance the tolerance of A. beshanzuensis to high temperatures. In summary, the research demonstrated that A. beshanzuensis could not tolerate high temperatures, which was identified as one of the primary reasons for its endangerment. This study offers a novel approach to investigating the regulatory mechanisms of heat stress.

UV-Curable Polyurethane-Based, Halogen-Free, CaB4O7 Nanoparticles Decorated, Flexible Flame-Retardant Films

Abstract In this study, combinations of phosphorous silicone methacrylate monomer (PSiMA) and CaB4O7 nanoparticles (CBO NPs) were prepared for formation of halogen-free, flame-retardant, UV-curable polyurethane acrylate (PUA) films. The addition of either PSiMA or CBO NPs to PUA increased the flame-retardancy as expected, but the PSiMA-only addition, unfortunately, had adverse effects on the physical properties. However, the combined addition of PSiMA and CBO NPs not only resulted in the best performance on flame retardancy but also recovered the polymer’s thermal and physical properties. With additives high initial decomposition temperatures were observed in the range of 175–216 °C. Among the combinations, PLU-60PSi-10NP (60 phr PSiMA + 10 phr CBO NPs) resulted in the best LOI performance of 27, which is 40% more than the PLU film (PUA-based film). In addition, the film had a remarkable char formation ability of 14.5% compared to PLU. The observed high LOI values could not be explained by the high percentages of P, Si, B, and N in the films, but the synergy among the additives was also considered. In this study, we have investigated the use of a promising technique, THz spectroscopy, on the characterization of these films as well. Very interestingly, the results showed a nice correlation between the dielectric responses measured by THz spectroscopy and the mechanical properties of the films. Observed great performances along with the simple preparation methods of these newly developed halogen-free, flame-retardant, PUA-based films are expected to significantly increase their potential use in many practical applications such as automobile, leather, printing, and coatings.

Photoelectric Performance of Two-Dimensional n-MoS2 Nanosheets/p-Heavily Boron-Doped Diamond Heterojunction at High Temperature

Two-dimensional (2D) n-MoS2 nanosheets (NSs) synthesized via the sol–gel method were deposited onto p-type heavily boron-doped diamond (BDD) film to form a n-MoS2/p-degenerated BDD (DBDD) heterojunction device. The PL emission results for the heterojunction suggest strong potential for applications using yellow-light-emitting optoelectronic devices. From room temperature (RT) to 180 °C, the heterojunction exhibits typical rectification characteristics with good results for thermal stability, rectification ratio, forward current decrease, and reverse current increase. Compared with the n-MoS2/p-lightly B-doped (non-degenerate) diamond heterojunction, the heterojunction demonstrates a significant improvement in both its rectification ratio and ideal factor. At 100 °C, the rectification ratio reaches the maximum value and is considered an ideal high temperature for achieving optimal heterojunction performance. When the temperature exceeds 140 °C, the heterojunction transforms into the Zener diode. The heterojunction’s electrical temperature dependence is due to the Fermi level shifting resulting in the weakening of the carrier interband tunneling injection. The n-MoS2 NSs/p-DBDD heterojunction will broaden future research application prospects in the field of high-temperature consumption in future optoelectronic devices.

Comparative Analysis of the Thermal Decomposition Process of Asbestos Wastes from Different Regions

Asbestos minerals were one of the most popular and cheapest raw materials used in the construction industry in the past. They were used primarily in the form of cement-asbestos composite material. Nowadays, we know that asbestos possesses carcinogenic properties. Due to this fact, asbestos was banned in many countries, especially in EU countries. All asbestos-containing materials are considered dangerous wastes and stored in special landfills, which causes significant environmental pollution. One of the proposed methods to solve this problem, may be thermal treatment during which the dangerous asbestos structure can be destroyed. Several asbestos-containing wastes from different countries were examined and compared. These asbestos-containing materials were characterised by chemical analysis (XRF) connected with mineralogical phase analysis by X-ray diffraction (XRD). The thermal decomposition of samples was studied by differential thermal analysis (DTA) and thermogravimetric measurements (TG/DTG). The material’s behaviour at high temperatures was also studied using a hightemperature microscope. Moreover, computer simulations connected with the formation of the liquid phase were also carried out by specialised engineering software. In this stage, based on data presented in available literature related to chemical composition, the behaviour of asbestos waste from different countries was also analysed and compared. The studies have shown a significant difference in the behaviour of the tested cementasbestos materials from different countries under high-temperature conditions. This may affect the prospects for reusing neutralised asbestos waste, especially in the context of the main mineral composition of thermally treated cementasbestos wastes. This fact implies possible directions for the economic management of such waste.

Distributed acoustic sensing in harsh environments based on femtosecond laser-inscribed ultra-short fiber Bragg grating arrays

We propose and demonstrate a high-performance DAS system using ultra-short fiber Bragg grating arrays (USFBG) and a phase-sensitive optical time domain reflectometry (φ-OTDR). A USFBG with an ultra-short length of 30 μm was successfully fabricated in a single-mode fiber (SMF) by femtosecond laser point-by-point inscription, exhibiting a large full width at half maximum (FWHM) bandwidth of 24.6 nm. To the best of our knowledge, this is the largest grating bandwidth reported to date. The ultra-large bandwidth effectively avoids the mismatch between the wavelength of the system light source and the grating caused by temperature changes. Moreover, a USFBG array with 300 identical USFBGs and an interval of 5 m was fabricated along the SMF to enhance the backscattering signal and suppress fading noise. An optical pulse compression algorithm was also deployed in the heterodyne φ-OTDR system to improve the spatial resolution. Thanks to the combination of USFBG arrays and the pulse compression φ-OTDR system, a long-distance DAS with a sensing distance of 60 km, a spatial resolution of 5.9 m, and an improved strain resolution of 13.9 pɛ/√Hz was achieved. Then, long-term high-temperature annealing was carried out, and the results showed that the fabricated USFBGs can withstand a high temperature of 1000°C. A high-temperature DAS system capable of operating at up to 1000°C was also demonstrated. As such, the proposed DAS systems could be used in harsh environments, such as aerospace vehicles, nuclear plants, and oil and gas exploration.

HDX-MS reveals pH and temperature-responsive regions on AAV capsids and the structural basis for DNA release.

Recombinant adeno-associated viruses (AAVs) have become increasingly popular as gene therapy vectors in recent years. Like all viruses, AAVs undergo dynamic structural changes in response to varying temperature and pH conditions. However, the specific capsid regions involved in these processes remain unknown. In this study, we employed Hydrogen-Deuterium Exchange Mass Spectrometry (HDX-MS) to investigate the impact of pH and temperature on the structure and conformational dynamics of AAV capsids. Our analysis identified specific regions of the capsid that are sensitive to these environmental changes. Additionally, our data elucidated the structural basis for DNA uncoating or leakage triggered by low pH or high temperature. Detailed structural characterization of AAVs by HDX-MS in this study deepens our understanding of viral capsid conformational dynamics and stability in AAV transduction and manufacturing and storage conditions, paving the way for formulation development and next-generation capsid engineering.

High-speed 850 nm oxide-confined vertical-cavity surface-emitting lasers at high temperature and cryogenic temperature

Abstract High-speed 850 nm oxide-confined vertical-cavity surface-emitting lasers (VCSELs) are key laser sources for short-reach optical interconnects in high-performance computing systems and future cryogenic computing systems. In this paper, we present high-speed 850 nm oxide-confined VCSELs operating at room temperature (RT), 85 °C (358 K), and 3.6 K. At RT, the VCSEL can realize a modulation bandwidth f− 3dB of 31.7 GHz and 52 Gbps non-return-to-zero (NRZ) data rate. At 85 °C, the VCSEL can achieve a modulation bandwidth f− 3dB of 26.5 GHz and 50 Gbps NRZ data rate without equalization and pre-emphasis. The cryogenic 850 nm oxide-confined VCSEL with a modulation bandwidth of 20.4 GHz at 3.6 K is demonstrated. Without pre-emphasis and equalization, the cryogenic VCSEL achieves a 32 Gbps NRZ data rate with a bit error rate of 2.1 × 10−12 at 3.6 K.

Synergistic mechanisms of temperature and strain rate on plastic deformation in SLM 3D printed SS316L utilizing hot processing map analysis

The plastic deformation behavior of selective laser melting (SLM) 3D printed SS316L steel has been analyzed at the temperature range 25- 1000℃ (25 (room temperature), 200, 400, 600, 800 and 1000℃) and strain rate range 10−3-103s−1 (10−3, 10−2, 10−1, 100, 101, 102 and 103 s−1) under compressive loading environments. The flow stress vs. plastic strain results revealed that the flow stress was reduced 136.64% from room temperature to 1000℃ at 10−3s−1. Further, the flow stress was decreased 102.86% from room temperature to 1000℃ at 103s−1. The flow stress was increased 46.63% from 10−3s−1 to 103s−1 at room temperature. Moreover, the flow stress was increased 95.07% from 10−3s−1 to 103s−1 at 1000℃. The temperature and strain rate effect on strain rate sensitivity (m) has been observed for SLM 3D printed SS316L steel. Based on strain rate sensitivity (m), the power dissipation efficiency () and instability dimensionless parameter () map plot contours have been investigated under various hot working parameters for SLM 3D printed SS316L steel. Further, hot working processing maps have been generated by superimposing instability dimensionless parameters () map on the power dissipation efficiency () map for SLM 3D printed SS316L steel. The processing map was further related with investigated material microstructure to identify the hot processing safe and unsafe zone for SLM 3D printed SS316L. The unsafe instability region occurred at the low strain rate range (10−2 – 10−1 s−1), high strain rate range (102-103 s−1) and temperature range (200–400℃, and 800 − 100℃) for 0.02, 0.04, 0.06, 0.08 and 0.10 strain. Further, the remaining area was useful for hot workability. The Vicker’s hardness revealed that the hardness was decreased with 3.87%, 12.55%, 22.01%, 32.35%, and 43.70% at 2000C, 4000C, 6000C, 8000C and 10000C respectively with respect to room temperature hardness.

Enhanced electrochemical performance of Na2FeP2O7 cathode material for sodium-ion batteries through composite with Cu3(PO4)2

Abstract Among the various polyanionic cathode materials for sodium-ion batteries, phosphate-based materials have demonstrated excellent electrochemical and thermal properties, thereby attracting considerable attention. Na2FeP2O7 stands out as one of the most stable cathode materials, distinguished by its well-defined pore structure and excellent cycling stability, and exceptional air stability. Nonetheless, due to the electron-blocking effect of the metal atoms, Na2FeP2O7 exhibits poor electronic conductivity. To address this, an appropriate amount of Cu3(PO4)2 is integrating with Na2FeP2O7 to synthesize the Na2FeP2O7@Cu3(PO4)2 (NFPO@CPH) composite material. Benefiting from the excellent electronic properties of Cu3(PO4)2, the composite enhances both electronic conductivity and Na+ ion diffusion capabilities of the material. Consequently, the NFPO@3%CPH electrode material exhibits a high specific capacity (88.1 mAh g−1) and excellent cycling stability, retaining 94% its capacity after 250 cycles at 0.1 C. Furthermore, it maintains excellent electrochemical performance under extreme conditions, such as a high temperature of 60 °C and a high mass loading of 11 mg cm−2. The full battery, when paired with hard carbon, achieves a discharge capacity of 82.2 mAh g−1 at 0.1 C, demonstrating its promise for practical application.

Thermal Rectification in Gradient Microfiber Textiles Enabling Noncontact and Contact Dual-Mode Radiative Cooling.

Radiative cooling textiles characterized by high solar scattering and significant mid-infrared emission properties present a promising energy-efficient solution for cooling objects exposed to high temperature and direct sunlight conditions. However, the inherent porous structure and thermal insulating properties of textiles pose challenges in effectively cooling self-heated objects. Herein, the fabrication of an ultra-flexible is presented, gradient-structured microfiber composite textile using a filtration-induced entrapment and hot-pressing method. This textile features a unique concentration gradient of thermally conductive boron nitride nanosheets across its thickness, leading to a gradient distribution of stacking pore sizes. This gradient configuration induces multiple Mie scattering across the entire spectrum of incident sunlight, thereby achieving an impressive solar reflectance of up to 97.3%. Moreover, this textile demonstrates a thermal rectification factor of 31.8%, enabling efficient dual-mode radiative cooling capabilities in both noncontact and contact scenarios. In noncontact cooling scenarios, this textile effectively reduces the temperatures of unheated and self-heated enclosed spaces by 9.2 and 8.7°C, respectively, outperforming typical textiles. Additionally, this textile shows enhanced radiative cooling capabilities in contact cooling scenarios, lowering the temperature of underlying self-heated objects by 8.6°C compared to typical textiles.

Amplified Heterogeneous Interface for Modulating High‐Frequency Polarization Response in Confined Space

Abstract Heterogeneous interface engineering is a promising strategy for high‐efficiency EM wave absorption. However, Ostwald ripening induced by high temperatures imposes inhibitory constraints on phase growth, thereby limiting the effects of heterogeneous interface amplification. In this study, heterogeneous interface modulation, atomic site design, and elemental competition strategies are employed to induce multiphase fission and atomic reconstruction processes, enabling the fabrication of (CozNi1−z)xSey@C composites with tailored interfacial microstructure and crystallographic phase composition. The confined carbon encapsulation structure is beneficial for promoting the in situ growth of selenides, which successfully induces an ultrahigh density heterostructure system (CoSe2, CoSe, NiSe2, and NiSe) at the nanoscale, breaking through the limits of heterointerface amplification in conventional binary element systems. This unique broadband dielectric evolution mechanism enables precise modulation of multistage quantum‐confined polarization resonance, resulting in a gradient leap forward of the dielectric loss tangent (tanδɛ) with increasing frequency in the high‐frequency regime, which demonstrates intense polarization relaxation response. The (CozNi1−z)xSey@C microspheres with ultrathin and strong attenuation properties achieve a minimum reflection loss (RLmin) of −51.5 dB at a thickness of only 1.5 mm. A synergistic multiple‐loss model is designed to amplify heterogeneous interfaces and modulate high‐frequency polarization response, providing inspiration for fabricating advanced EM wave absorbers.

Comparison of stress tolerance mechanisms between Saccharomyces cerevisiae and the multi-stress-tolerant Pichia kudriavzevii.

Yeasts play a vital role in both research and industrial biomanufacturing. Saccharomyces cerevisiae has been extensively utilized as a model system. However, its application is often constrained by limited tolerance to the diverse stress conditions encountered in bioprocesses. These challenges have driven increasing interest in non-conventional, multi-stress tolerant yeasts as alternative biomanufacturing hosts. This review highlights Pichia kudriavzevii as a promising non-conventional yeast for industrial applications. Unlike S. cerevisiae, P. kudriavzevii exhibits exceptional tolerance to high temperatures, elevated concentrations of furanic and phenolic inhibitors, osmotic stress, salinity, and extreme pH. These traits make it an attractive candidate for industrial processes without requiring extensive genetic modifications to enhance stress resistance. As a result, P. kudriavzevii has emerged as a flagship species for advancing bioeconomy. Despite its industrial potential, the molecular mechanisms underlying P. kudriavzevii's superior stress tolerance remain poorly understood. This review compiles current knowledge on P. kudriavzevii and compares its stress tolerance mechanisms with those of S. cerevisiae, providing insights into its innate resilience. By expanding our understanding of non-conventional yeasts, this review aims to facilitate their broader adoption as robust microbial platforms for industrial biomanufacturing.

Evaluation of Surface Integrity of Multi-Energy Field Coupling-Assisted Micro-Grinding Hastelloy Alloy

Hastelloy is widely used in the manufacturing of high-temperature components in the aerospace industry because of its high strength and corrosion-resistant physical properties, as well as its ability to maintain excellent mechanical properties at high temperatures. However, with developments in science and technology, the amount of available components for use in high-temperature and corrosive environments is increasing, their structures are becoming more complex and varied, and requirements with regard to the surface quality of the components has also become more stringent. The integration of cold plasma (CP) and nano-lubricant minimum quantity lubrication (NMQL), within a multi-physics coupling-assisted micro-grinding process (CPNMQL), presents a promising strategy to overcome this bottleneck. In this paper, micro-grinding of Hastelloy C-276 was performed under dry, CP, NMQL, and CPNMQL conditions, respectively. Contact angle testing, X-ray photoelectron spectroscopy (XPS) analysis, and nano-scratch experiments were used to investigate the mechanism of CPNMQL and to compare the micro-milling performance under different cooling and lubrication conditions employing various characteristics such as grinding temperature, surface roughness, and 3D surface profile. The results showed that at different micro-grinding depths, the micro-grinding temperature and surface roughness were significantly reduced under CP, NMQL, and CPNMQL conditions compared to dry friction. Among them, CPNMQL showed the best performance, with 53.4% and 54.7% reductions in temperature and surface roughness, respectively, compared to the dry condition.

Quaternary Layered Boride Ti4MoSiB2: A Structure-Function Integrated High-Temperature Self-Lubricating and Negative-Wear Material.

As a newly emerging class of materials, quaternary layered borides are promising structural-functional integration materials. However, there have been very few systematic and in-depth studies in many areas of these materials, including high-temperature lubrication. In this study, a novel out-of-plane chemically ordered Ti4MoSiB2 MAB phase material is synthesized and its mechanical and tribological properties are investigated over a wide temperature range. Experiments and calculations are conducted to determine its mechanical failure, friction, and wear mechanisms. The results indicate that the synthesized material maintains desirable comprehensive mechanical properties from room temperature to 1273 K and exhibits excellent lubricating and wear resistance performance at high temperatures. In this study, the operating principles of the anisotropic thermal expansion of crystals on the fracture behaviors, and the tribological chemical reactions and oxygen vacancies on tribological properties, are explained. This study is expected to provide a foundation for future practical applications in high-temperature environments.

Transition-Metal Nitrides for High-Temperature Structural Colors.

Transition-metal nitrides (TMNs), such as hafnium nitride (HfN), titanium nitride (TiN), and zirconium nitride (ZrN), have emerged as highly promising materials in photonics and plasmonics, drawing significant interest due to their optical properties comparable to those of conventional plasmonic materials like Ag and Ag, with remarkable thermal and chemical stability. While TMNs possess high bulk melting points and impressive resistance to degradation, the impact of scaling down to nanoscale dimensions and exposure to oxidizing environments under high temperatures on their optical properties remains largely underexplored. In this work, we establish a comprehensive experimental framework combining in situ optical characterization and ex situ surface analysis to explore the behavior of TMNs at 600 °C with exposure to oxygen. This oxidation process enables gradual color transitions in TMNs, thereby opening pathways for innovative applications in high-temperature structural color for printing. We further investigate aluminum oxide (Al2O3) as a protective coating to effectively prevent oxidation and preserve optical behaviors up to 830 °C, making these coatings suitable for applications in demanding thermal environments. The findings highlight TMNs' potential in next-generation high-temperature photonic devices, balancing optical performance and durability in challenging environments.

Low-energy electron microscopy investigation of germanene segregation on Ag(111) thin films

Abstract We used low-energy electron microscopy to investigate the formation processes of various surface structures on Ag(111) thin films grown on Ge(111) during Ge segregation. During annealing the Ag(111) samples cleaned by Ar+ sputtering, the Ag2Ge surface alloy first appeared along the Ag grain boundaries, signifying preferential diffusion of Ge atoms through these boundaries. Subsequent annealing at higher temperatures induced the phase transformation from the surface alloy to germanene. However, further higher temperature annealing caused back-diffusion of Ge atoms into the Ag thin films, reverting to the surface alloy. Formation of the ordered (7√7×7√7)R±19.1° germanene required cooling from high temperatures around 500 °C. However, high-temperature annealing occasionally resulted in the formation of three-dimensional (3D) Ge islands on the surface. During cooling, the 3D islands absorbed Ge atoms from the surrounding germanene, triggering phase transformation to the surface alloy in the vicinity of the islands.