Mechanically activated self-propagating high-temperature synthesis of titanium silicide-molybdenum disilicide composite using constituent elements.

Silicides with potential to form a protective silica layer have garnered considerable attention as engineering ceramic materials. This research investigates the influence of initial composition and mechanical activation on the synthesis performance and microstructure of products in the Ti-Si-Mo system. Several compositions, including Ti8Mo29Si63, Ti15Mo25Si60, Ti22Mo22Si56, Ti40Mo12Si48, Ti52Mo6Si42, Ti62.5Si37.5, and Mo33Si67, were prepared and synthesized via mechanically activated self-propagating high-temperature synthesis (MASHS). XRD, SEM, and EDS analyses, along with related investigations such as grain size calculations and morphology studies, were performed. The results indicate that at low Ti concentrations, the composite contains (Ti0.8,Mo0.2)Si2 and MoSi2, whereas moderate Ti concentrations enable the formation of the MoSi2-Ti5Si3 composite. Moreover, a high amount of Mo can extensively dissolve into the titanium and titanium silicide structure, resulting in the synthesis of the (Ti,Mo)5Si3 phase in Ti-rich samples. The dissolution of Mo in the crystal structure of the compound decreases the lattice parameters of titanium silicide. Furthermore, mechanical activation facilitates the initiation of reactions in compositions with lower Ti content and yielding fine-grained products.

Physiological responses contributing to multiple stress tolerance in Pichia kudriavzevii with potential enhancement for ethanol fermentation.

Economically feasible ethanol production requires efficient hydrolysis of lignocellulosic biomass and high-temperature processing to enable simultaneous saccharification and fermentation. During the lignocellulolysic hydrolysate, the yeast must encounter with a multiple of inhibitors such as heat and furfural. To solve this problem, a potential fermentative yeast strain that tolerated simultaneous multistress and enhance ethanol concentration was investigated. Twenty yeast isolates were classified into two major yeast species, namely Pichia kudriavzevii (twelve isolates) and Candida tropicalis (eight isolates). All P. kudriavzevii isolates were able to grow at high temperature (45 °C) and exhibited stress tolerance toward furfural. Among P. kudriavzevii isolates, NUCG-S3 presented the highest specific growth rate under each stress condition of heat and furfural, and multistress. Morphological changes in P. kudriavzevii isolates (NUCG-S2, NUCG-S3, NUKL-P1, NUKL-P3, and NUOR-J1) showed alteration in mean cell length and width compared to the non-stress condition. Ethanol production by glucose was also determined. The yeast strain, NUCG-S3, gave the highest ethanol concentrations at 99.46 ± 0.82, 62.23 ± 0.96, and 65.80 ± 0.62 g/l (P < 0.05) under temperature of 30 °C, 40 °C, and 42 °C, respectively. The tolerant isolated yeast NUCG-S3 achieved ethanol production of 53.58 ± 3.36 and 48.06 ± 3.31 g/l (P < 0.05) in the presence of 15 mM furfural and multistress (42 °C with 15 mM furfural), respectively. Based on the results of the present study, the novel thermos and furfural-tolerant yeast strain P. kudriavzevii NUCG-S3 showed promise as a highly proficient yeast for high-temperature ethanol fermentation.

SlWRKY55 coordinately acts with SlVQ11 to enhance tomato thermotolerance by activating SlHsfA2.

High temperature (HT) severely restricts plant growth, development, and productivity. Plants have evolved a set of mechanisms to cope with HT, including the regulation of heat stress transcription factors (Hsfs) and heat shock proteins (Hsps). However, it is not clear how the transcriptional and translational levels of Hsfs and Hsps are controlled in tomato. Here, we reported that the HT-induced transcription factor SlWRKY55 recruited SlVQ11 to coordinately regulate defense against HT. SlWRKY55 directly bound to the promoter of SlHsfA2 and promoted its expression, which was increased by SlVQ11. Moreover, both SlWRKY55 and SlVQ11 physically interacted with SlHsfA2 to enhance the transcriptional activity of SlHsfA2. Thus, our results revealed a molecular mechanism that the SlWRKY55/SlVQ11-SlHsfA2 cascade enhanced thermotolerance and provided potential target genes for improving the adaptability of crops to HT.

Engineering of LiTaO3 Nanoparticles by Flame Spray Pyrolysis: Understanding In Situ Li-Incorporation into the Ta2O5 Lattice.

Lithium tantalate (LiTaO3) perovskite finds wide use in pyroelectric detectors, optical waveguides and piezoelectric transducers, stemming from its good mechanical and chemical stability and optical transparency. Herein, we present a method for synthesis of LiTaO3 nanoparticles using a scalable Flame Spray Pyrolysis (FSP) technology, that allows the formation of LiTaO3 nanomaterials in a single step. Raman, XRD and TEM studies allow for comprehension of the formation mechanism of the LiTaO3 nanophases, with particular emphasis on the penetration of Li atoms into the Ta-oxide lattice. We show that, control of the High-Temperature Particle Residence Time (HTPRT) in the FSP flame, is the key-parameter that allows successful penetration of the -otherwise amorphous- Li phase into the Ta2O5 nanophase. In this way, via control of the HTPRT in the FSP process, we synthesized a series of nanostructured LiTaO3 particles of varying phase composition from {amorphous Li/Ta2O5/LiTaO3} to {pure LiTaO3, 15-25 nm}. Finally, the photophysical activity of the FSP-made LiTaO3 was validated for photocatalytic H2 production from H2O. These data are discussed in conjunction with the role of the phase composition of the LiTaO3 nanoparticles. More generally, the present work allows a better understanding of the mechanism of ABO3 perovskite formation that requires the incorporation of two cations, A and B, into the nanolattice.

Effect of Titanium Dioxide Particles on the Thermal Stability of Silica Aerogels.

Silica aerogels exhibit a unique nanostructure with low thermal conductivity and low density, making them attractive materials for thermal isolation under extreme conditions. The TiO2 particle is one of the common industrial additives used to reduce the thermal radiation of aerogel composites under high-temperature environments, but its influence on thermal resistance is almost unknown. Herein, we report the effect of TiO2 nanoparticles with different crystal phases and different sizes on the thermal stability of silica aerogel composites. By adding TiO2 nanoparticles, the aerogel can significantly resist collapse at high temperatures (up to 1000 °C). And compared with the rutile phase TiO2, the anatase phase TiO2 shows much higher temperature resistance performance, with shrinkage of only one-sixth of the rutile phase after 800 °C treatment. Interestingly, energy-dispersive spectrometer mapping results show that after 800 °C treatment, silica nanoparticles (NPs) are squeezed out in between anatase TiO2 particles, which resists the coarsening of silica NPs and ultimately enhances the stability of aerogel composites. The optimal anatase phase TiO2-doped silica aerogel demonstrates the integrated properties of crack-free morphology (2.84% shrinkage), low thermal conductivity (29.30 mW/(m·K)) and low density (149.4 mg/cm3) after 800 °C treatment. This study may provide new insights for developing oxide-doped silica aerogels with both high-temperature resistance and low thermal radiation.

Study on the influence of active oxygen on the natural oxidation of arsenopyrite under different temperature conditions.

Arsenic (As), a toxic element, contaminates farmlands, rivers, and groundwater, posing severe environmental and health risks. Notably, As-containing materials in tailings are affected by temperature variations during long-term storage, and this considerably impact the oxidation and migration of elements in arsenopyrite.This study focused on arsenopyrite and investigated the process of its oxidative dissolution and release of arsenic under different temperature conditions by using in-situ XRD, in-situ XPS and electron paramagnetic resonance spectroscopy(EPR), The role of oxygen free radicals in the oxidation of arsenopyrite was elucidated. It has been established that under high-temperature conditions As, iron (Fe), and sulfur (S) are primarily present As(V)/As(IV), Fe(III), and SO42-, respectively. The O2⋅- generated during the oxidation of As(III) by O2, OH⋅ produced by the Fe(II)/FeOH2+ reaction, and H2O2 formed via their interaction play a crucial role in the photochemical oxidation of arsenopyrite. These findings provide a theoretical basis for the formation of ferric arsenate precipitation, contributing in the adsorption and immobilisation of oxidatively released arsenic.

Characteristics and release potential of microplastics in municipal solid waste incineration bottom ash.

Incineration is an effective method for reducing and safely treating municipal solid waste. However, microplastics (MPs) inevitably remain in the bottom ash, potentially introducing new pollution risks during subsequent treatment processes. This study conducted an analysis of the accumulation and release potential of MPs in bottom ash samples collected from 4 municipal solid waste incineration plants in Zhejiang, China. The results showed that the abundance of MPs ranged from 20 to 118 items g-1. Remarkably, MPs were found to accumulate predominantly in smaller bottom ash particles below 4.75 mm accounted for up to 70% of the total MPs. Most MPs in the bottom ash were under 100 µm in size, with a majority exceeding 50% being less than 50 µm, typically manifesting as shafts and fibers. In scenarios of secondary crushing, the abundance of MPs increased gradually with the degree of bottom ash crushing. When bottom ash was crushed to a particle size of less than 0.6 mm, the abundance of MPs reached up to 87-901 items g-1, which is 5-10 times higher than the original bottom ash. It is estimated that the annual release of MPs may reach up to 4.05 × 1016 particles. Re-incinerating thoroughly crushed bottom ash at 600 °C successfully decomposed the MPs. Mechanical stress can significantly increase the risk of MPs releasing in bottom ash. This risk can be eliminated by using secondary incineration to achieve complete MPs decomposition.

High-Temperature Water Electrolysis Properties of Membrane Electrode Assemblies with Nafion and Crosslinked Sulfonated Polyphenylsulfone Membranes by Using a Decal Method.

To improve the stability of high-temperature water electrolysis, I prepared membrane electrode assemblies (MEAs) using a decal method and investigated their water electrolysis properties. Nafion 115 and crosslinked sulfonated polyphenylsulfone (CSPPSU) membranes were used. IrO2 was used as the oxygen evolution reaction (OER) catalyst, and Pt/C was used as the hydrogen evolution reaction (HER) catalyst. The conductivity of the CSPPSU membrane at 80 °C and 90% RH (relative humidity) is about four times lower than that of the Nafion 115 membrane. Single-cell water electrolysis was performed while measuring the current density and performing electrochemical impedance spectroscopy (EIS) at cell temperatures from 80 to 150 °C and the stability of the current density over time at 120 °C and 1.7 V. The current density of water electrolysis using Nafion 115 and CSPPSU membranes at 150 °C and 2 V was 1.2 A/cm2 for both. The current density of the water electrolysis using the CSPPSU membrane at 120 °C and 1.7 V was stable for 40 h. The decal method improved the contact between the CSPPSU membrane and the catalyst electrode, and a stable current density was obtained.

Stability and Performance of Commercial Membranes in High-Temperature Organic Flow Batteries.

Redox flow batteries (RFB) often operate at extreme pH conditions and may require cooling to prevent high temperatures. The stability of the battery membranes at these extreme pH-values at high temperatures is still largely unknown. In this paper, a systematic screening of the performance and stability of nine commercial membranes at pH 14 and pH ≤ 0 with temperatures up to 80 °C is conducted in an organic aqueous RFB. Swelling, area resistance, diffusion crossover, battery performance and membrane stability after 40-80 °C temperature treatment are shown, after which a recommendation is made for different user scenarios. The Aquivion E98-05 membrane performed best for both the Tiron/2,7-AQDS battery and the DHPS/Fe(CN)6 battery at 40 mA/cm2, with stable results after 1 week of storage at 80 °C. At 80 mA/cm2, E-620-PE performed best in the DHPS/Fe(CN)6 battery, while Sx-050DK performed best in the Tiron/2,7-AQDS battery.

Synthesis and Performance Evaluation of High-Temperature-Resistant Extreme-Pressure Lubricants for a Water-Based Drilling Fluid Gel System.

Addressing the high friction and torque challenges encountered in drilling processes for high-displacement wells, horizontal wells, and directional wells, we successfully synthesized OAG, a high-temperature and high-salinity drilling fluid lubricant, using materials such as oleic acid and glycerol. OAG was characterized through Fourier-transform infrared (FTIR) spectroscopy and thermogravimetric analysis (TGA). The research findings demonstrate the excellent lubricating performance of OAG under high-temperature and high-salinity conditions. After adding 1.0% OAG to a 4% freshwater-based slurry, the adhesion coefficient of the mud cake decreased to 0.0437, and at a dosage of 1.5%, the lubrication coefficient was 0.032, resulting in a reduction rate of 94.1% in the lubrication coefficient. After heating at 200 °C for 16 h, the reduction rate of the lubrication coefficient reached 93.6%. Even under 35% NaCl conditions, the reduction rate of the lubrication coefficient remained at 80.3%, indicating excellent lubrication retention performance. The lubricant OAG exhibits good compatibility with high-density drilling fluid gel systems, maintaining their rheological properties after heating at 200 °C and reducing filtration loss. The lubrication mechanism analysis indicates that OAG can effectively adsorb onto the surface of N80 steel sheets. The contact angle of the steel sheets increased from 41.9° to 83.3° before and after hot rolling, indicating a significant enhancement in hydrophobicity. This enhancement is primarily attributed to the formation of an extreme-pressure lubricating film through chemical reactions of OAG on the metal surface. Consequently, this film markedly reduces the friction between the drilling tools and the wellbore rocks, thereby enhancing lubrication performance and providing valuable guidance for constructing high-density water-based drilling fluid gel systems.

Evolution Process of Fault Silica Aerogel under High Temperatures: A Molecular Dynamics Approach.

Building fire will seriously threaten human safety. Silica aerogel with low thermal conductivity and thermal stability as fire-retardant material has been widely used in building fireproof structures. However, the natural fragility of silica aerogel will limit its application. In this work, the effects of faults on the thermal stability of silica aerogel are studied by molecular dynamics simulation with large simulation time (20 ns). Additionally, the atomic model of silica aerogel with random faults is built by a straining structure (tensile strains are 10%, 20%, 30%, and 40%). It is found that when the tensile strain is less than 20%, the silica backbone can remain stable. The effects of faults on the thermal stability can be neglected. The silica backbone thermally vibrates during the heating process. However, when the tensile strain is over 30%, it is observed that the faults will enhance the silica backbone merging. Silica aerogel can be stable under 800 K. It is believed that the results of this study will pave the way for the development of fireproof materials.

Achieving Super-Metallophobicity on Silicon-based Ceramics at High Temperature.

As a critical concept in physical chemistry, superwettability is widely concerned in both fundamental science and practical engineering in past few decades. Despite this, investigation on high temperature superwettability is still a void, which is significant both in scientific and industrial fields. Herein, a ceramic with specific high temperature non-wetting property, Si2N2O is proposed. Compared with other materials, Si2N2O is elucidated with better practical non-wetting property against various non-ferrous metals. Combining with micro-nanostructures, the metallophobicity is further improved (contact angle >150° and contact angle hysteresis ≈0°). The extraordinary metal repellency is defined as "super-metallophobicity", which is proved to be induced by distinctive thermodynamic and dynamic wetting behavior on the rough surface. The research of super-metallophobicity not only sheds light on superwettability at high temperature, but also offers worthy insights for future potential material design in a wide range of applications, such as metallurgy, 3D printing and semiconductor industry.

Development of surfactant formulation for high-temperature off-shore carbonate reservoirs.

The residual oil left behind after water flooding in petroleum reservoirs can be mobilized by surfactant formulations that yield ultralow interfacial tension (IFT) with oil. However, finding ultralow IFT surfactant formulations is difficult for high-temperature, off-shore, carbonate reservoirs. These reservoirs are often water-flooded with seawater (with a lot of divalent ions), which is often incompatible with many surfactants at high temperatures. The goal of this research is to develop a surfactant formulation for an off-shore carbonate reservoir at 100°C previously flooded by seawater. Surfactant-oil-brine phase behavior was studied for formulations, starting from a single surfactant to mixtures of surfactants and a co-solvent. Mixtures of three surfactants and one co-solvent were needed to produce ultralow IFT formulations for the oil of interest. The surfactant system with polymer mobility control was tested in crushed reservoir rock packs. The cumulative oil recovery was >99% for the surfactant-polymer (SP) flood with an optimal salinity gradient. The constant salinity SP floods with seawater increased oil recovery significantly beyond the water flood (cumulative oil recovery >91%), even though the recovery was lower than that of the optimal salinity gradient SP flood. Our experimental work demonstrates the effectiveness of the surfactant formulation for a high-temperature carbonate reservoir at seawater salinity.

A novel white Y2(Ti0.8Hf0.2)2O7: Eu phosphors regulated by HfO2 exhibiting low color shifting for high temperature.

The development of white phosphors that can be activated in near-ultraviolet light is highly important in the field of LED lighting. In this work, a series of color-tunable Y2(Ti1-xHfx)2O7:Eu phosphors were prepared by adjusting the HfO2 and Eu3+ concentrations. In particular, white Y2(Ti0.8Hf0.2)2O7:Eu phosphors were successfully synthesized and emitted a broad band covering the entire visible light region upon excitation with 340 nm UV light. The white banded materials were composed of Eu2+ and Eu3+ emissions and HfO2 defect emission. The formation of Eu2+ ions was caused by the introduction of HfO2, which causes self-reduction of Eu3+ ions but does not require additional reducing agents. The white Y2(Ti0.8Hf0.2)2O7:Eu phosphors exhibit low color shifting at high temperature, which is very important for LED applications. The chromaticity shift of the Y2(Ti0.8Hf0.2)2O7:0.2Eu phosphor is 2.83 × 10-2 at 503 K, which is only 54.8 % that of commercial three-color white phosphors at the same temperature. The Ra value did not decrease significantly with increasing temperature and reached 90.2 at 383 K. Y2 (Ti0.8Hf0.2)2O7:0.2Eu phosphors were assembled with a 365 nm LED chip to fabricate a WLED device that showed excellent white-colored coordinates (0.345, 0.358) and a high Ra value of 90.1 under a 300 mA current.

Broad bandwidth and excellent thermal stability in BiScO3-PbTiO3 high-temperature ultrasonic transducer for non-destructive testing.

High-temperature ultrasonic transducer (HTUT) is essential for non-destructive testing (NDT) in harsh environments. In this paper, a HTUT based on BiScO3-PbTiO3 (BS-PT) piezoelectric ceramics was developed, and the effect of different backing layers on its bandwidth were analyzed. The HTUT demonstrates a broad bandwidth and excellent thermal stability with operation temperature up to 400 °C. By using a 10 mm thick porous alumina backing layer, the HTUT achieves a broad -6 dB bandwidth of 100 %, which is about 4 times superior to the transducer with an air backing layer. The center frequency (fc) of the HTUT remains stable with fluctuations of less than 10 % across the temperature range from room temperature to 400 °C. The HTUT successfully detected simulated defects in pulse-echo mode for NDT over 200 °C. This research not only advances high-temperature ultrasonic transducer technology but also expands the NDT applications in harsh environmental conditions.

PGPR isolated from hot spring imparts resilience to drought stress in wheat (Triticum aestivum L.).

Drought is a major abiotic stress that occurs frequently due to climate change, severely hampers agricultural production, and threatens food security. In this study, the effect of drought-tolerant PGPRs, i.e., PGPR-FS2 and PGPR-VHH4, was assessed on wheat by withholding water. The results indicate that drought-stressed wheat seedlings treated with PGPRs-FS2 and PGPR-VHH4 had a significantly higher shoot and root length, number of roots, higher chlorophyll, and antioxidant enzymatic activities of guaiacol peroxidase (GPX) compared to without PGPR treatment. The expression study of wheat genes related to tryptophan auxin-responsive (TaTAR), drought-responsive (TaWRKY10, TaWRKY51, TaDREB3, and TaDREB4) and auxin-regulated gene organ size (TaARGOS-A, TaARGOS-B, and TaARGOS-D) exhibited significantly higher expression in the PGPR-FS2 and PGPR-VHH4 treated wheat under drought as compared to without PGPR treatment. The results of this study illustrate that PGPR-FS2 and PGPR-VHH4 mitigate the drought stress in wheat and pave the way for imparting drought in wheat under water deficit conditions. Among the two PGPRs, PGPR-VHH4 more efficiently altered the root architecture to withstand drought stress.

Introduction of the prompt γ-ray neutron activation analysis system at CARR and the first pilot experiment on boron-containing high-temperature alloys.

A prompt γ-ray neutron activation analysis system has recently been developed at China advanced research reactor (CARR), the 60 MW research reactor in China Institute of Atomic Energy (CIAE). The system is set at the cold neutron beam guide with a thermal equivalent neutron flux at the sample position of 1.0 × 109 n·cm-2·s-1 with the power of 30 MW, and it is mainly composed of a neutron beam collimator, a sample chamber, a beam stopper, neutron and γ-ray shieldings and a detection system. The detection system can realize three modes of measurement: single, Compton suppression, and pair modes. The detection efficiency was calibrated up to 11 MeV using a set of radionuclides and the (n, γ) reactions of N and Cl. Boron, one of the most important elements in high-temperature alloy material studies, was analyzed in this work, as the first pilot experiment of the CARR-PGNAA system. The analytical sensitivity of 2000 cps/mg-B was obtained. The results verified the feasibility of the CARR-PGNAA system to measure boron in high-temperature alloys, and laid a foundation for the accurate quantification of boron in the next step.

Effects of high temperature on the growth performance and midgut autophagy of thermotolerant and thermosensitive silkworm strains.

High temperature stress has long-term negative effects on the growth and development of silkworm (Bombyx mori). Different silkworm varieties show the different tolerance to high temperature. The induction of autophagy is linked to increased thermotolerance in diverse ectothermic organisms. However, the function of autophagy in the thermotolerant and thermosensitive silkworm strains under high-temperature conditions remains unclear. The thermotolerant Liangguang NO.2 and thermosensitive Jingsong × Haoyue strains were used to explore the role of autophagy in thermotolerance. Here, we first found that the larval body weight gain was increased in the thermosensitive Jingsong × Haoyue strain, but there was no difference in the thermotolerant Liangguang NO.2 strain under high temperature conditions. High temperature stress had a negative influence on the cocoon performance in both the Liangguang NO.2 and Jingsong × Haoyue strains. Additionally, the autophagy-related gene Atg5 mRNA expression in the Liangguang NO.2 strain was upregulated by high temperature, while the expression of Atg12 mRNA was reduced in the Jingsong × Haoyue strain. Titers of 20-Hydroxyecdysone and the ultraspiracle 1 mRNA expression in the Liangguang NO.2 strain were upregulated by high temperature, which might be associated with the induction of autophagy. These results demonstrate the potentially regulatory mechanism of autophagy in silkworms' tolerance to high temperature, providing a theoretical basis for exploring the physiological mechanism of thermotolerance in insects.

Design of a Thermally Stable Heat-Resistant (Al2O3+Al3Ti)/Al Composite with Excellent High-Temperature Mechanical Properties: Multimechanism Synergistic Strengthening Strategy.

The effectiveness of the room-temperature strengthening strategy for aluminum (Al) is compromised at increased temperatures due to grain and precipitate phase coarsening. Overcoming the heightened activity of grain boundaries and dislocations poses a significant challenge in enhancing the high-temperature strength through traditional precipitation strengthening. This study presents novel strengthening strategies that integrate intergranular reinforcements, intragranular reinforcements, refined grain, and stacking faults within an (Al2O3+Al3Ti)/Al composite prepared using sol-gel and powder metallurgy technology. Excellent high-temperature tensile properties are achieved; also, a remarkable fatigue performance at increased temperatures that surpasses those of other existing Al alloys and composites is revealed. These superior characteristics can be attributed to its exceptionally stable microstructure and the synergistic strengthening mechanisms mentioned above. This work offers new insights into designing and fabricating thermally stable Al matrix composites for high-temperature applications.

Effect of phytohormone on proliferation and accumulation of cellular metabolites of microalgae Isochrysis zhanjiangensis.

Phytohormones play a role in regulating microalgae cells tolerance to adversity. This paper examines the effects of different temperatures (20 °C, 25 °C, 30 °C and 35 °C) on the physiological characteristics and endogenous phytohormones of the Isochrysis Zhanjiangensis (IZ) and its mutagenic strain (3005). The results showed that the endogenous phytohormones indole acetic acid (IAA) and jasmonic acid (JA) exhibited significant differences (P<0.05) between the two strains. The addition of 0.5 mg·L-1 exogenous JA inhibitor ibuprofen (IBU) improved cell growth of IZ, and was extremely effective in the accumulation of polysaccharides, which accounted for 33.25 %. Transcriptomic analyses revealed that genes involved in photosynthesis, such as PetC and PsbO, exhibited significantly elevated expression of the strain IZ, while the pathways related to JA synthesis may be the factor affecting microalgae temperature tolerance. This study provides a theoretical foundation for elucidating the underlying mechanisms and potential applications for high temperature tolerance in IZ.