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Enhancing particle heat resistance of the silicon-oxygen network skeleton in silica aerogel via Y/Yb dual-doping for thermal insulation

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Ceramics International 2025年

作者： Wu, Sijia Yu, Yuxi Luo, Zhong Huang, Liuying Fu, Zhongyi Zhao, Shuyuan College of Materials Xiamen University Xiamen361005 China China Aviation Power Machinery Research Institute Zhuzhou412002 China College of Naval Architecture & Ocean Engineering Naval University of Engineering Wuhan430033 China National Key Laboratory of Science and Technology on Advanced Composites in Special Environments Harbin Institute of Technology Harbin150080 China

SiO2 aerogels are nanoporous thermal insulation materials composed of a network of interconnected nanoparticles, but they are easy to crack and collapse above 800 °C which resulting in failure of thermal insulation. To improve the temperature resistance of nanoparticles, rare earth elements yttrium (Y) and ytterbium (Yb) were introduced as an enhancement system by sol-gel method to change the chemical interaction on the chemical structure and molecular bonding, together with improving the thermal stability. TEOS as the silicon source, yttrium nitrate and ytterbium nitrate as the rare earth sources, aerogel material with a density of 0.0904 g/cm3 was prepared by adjusting the finally chosen molar ratio of Si:Y:Yb = 1:0.05:0.05. By investigating the influence of RE on the microstructure, Y and Yb were found to be involved in the molecular bonding forming Si-O-Y and Si-O-Yb and changing the surface of primary particles. The thermal stability showed that the phase transition process after 573 °C was greatly inhibited by the introduction of single or dual RE. By analyzing the high temperature microstructural evolution, the shrinkage was decreased 25 % when at 1200 °C. The Cristobalite phase above 1200 °C was inhibited due to the Y/Yb dual-doping system. Furthermore, the decomposition stability was enhanced and the crack formation was significantly reduced at 1000 °C with thermal conductivity reducing from 0.2111W/(m·K) to 0.1187 W/(m·K) after heat treatment at 1000 °C. © 2025 Elsevier Ltd and Techna Group S.r.l.

关键词： Sol-gel process

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Active control of thermoacoustic instability in a lean-premixed hydrogen-enriched combustor via open-loop acoustic forcing

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Combustion and Flame 2025年 277卷

作者： Liao, Yu Choi, Yongseok Liu, Peijin Kim, Kyu Tae Guan, Yu Department of Aeronautical and Aviation Engineering The Hong Kong Polytechnic University Kowloon Hong Kong National Key Laboratory of Solid Rocket Propulsion Northwestern Polytechnical University Xi'an710072 China Department of Aerospace Engineering Korea Advanced Institute of Science and Technology Daejeon34141 Korea Republic of

Open-loop control is proven effective in mitigating self-excited oscillations in conventional hydrocarbon-fueled combustors, but its effectiveness in hydrogen-fueled combustors remains unknown. This study experimentally investigates the effectiveness of open-loop acoustic forcing in mitigating self-excited periodic thermoacoustic oscillations in a lean-premixed, hydrogen-enriched turbulent combustor. We conducted experiments across a range of hydrogen volume fractions (20% to 50%), varying both the frequencies and amplitudes of the acoustic forcing introduced via three loudspeakers positioned upstream of the combustor. For the first time, we have demonstrated the effectiveness of open-loop acoustic forcing in mitigating self-excited periodic thermoacoustic oscillations in a hydrogen-enriched combustor, with suppression effects becoming more pronounced as the hydrogen content increases. We achieve up to a 90% reduction in pressure amplitude with minimal energy input—less than 1% of the combustor's thermal power. At lower hydrogen fractions, the acoustic forcing fails to effectively decouple the flame dynamics from the acoustic field, resulting in significant oscillation amplification, with natural mode amplitudes increasing by over 2000%. A critical transition from global amplification to suppression occurs at a hydrogen volume fraction of 40%, where successful decoupling between the flame dynamics from the acoustic field is observed. These findings highlight the potential of open-loop control for mitigating thermoacoustic oscillations in hydrogen-enriched combustion systems, offering a promising approach to aid the decarbonization of gas turbines. Novelty and significance statement This study provides the first experimental evidence that open-loop acoustic forcing can effectively suppress thermoacoustic oscillations in hydrogen-enriched turbulent combustors. We show that increasing hydrogen volume fraction (20% to 50%) in the reactant mixtures enhances oscillation s

关键词： Combustors

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Symmetry-oriented enumeration method for molecular crystal structure prediction and its application

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Physical Review B 2025年第13期111卷 134112-134112页

作者： Yu Xin Zhuohang Xie Yongshuo Chen Pengyue Gao Hong Jian Zhao Jian Lv Yanchao Wang Yanming Ma Key Laboratory of Material Simulation Methods and Software of Ministry of Education College of Physics Jilin University Changchun 130012 China International Center of Future Science Jilin University Changchun 130012 China Key Laboratory of Physics and Technology for Advanced Batteries (Ministry of Education) College of Physics Jilin University Changchun 130012 China State Key Laboratory of High Pressure and Superhard Materials College of Physics Jilin University Changchun 130012 China

Predicting the thermodynamically stable arrangements of molecular building blocks is crucial for understanding the properties and behaviors of crystalline molecular compounds. Several molecular structure prediction methods have been proposed, leading to successful applications. However, some evolutionary approaches that involve direct sampling within the infinite atomic coordinate space, without symmetry-preserving constraints, tend to suffer from biased sampling, where structures with P1 symmetry become disproportionately dominant. To overcome this limitation, we propose a method that utilizes a finite set of symmetrically inequivalent Wyckoff encodes to sparsely represent the search space of crystalline molecular compounds, thereby improving the coverage of the search space. This method can be used to predict the molecular crystal structures with varying numbers of molecules in the asymmetric unit, from fractional to multiple integers. The applications of this method to three-dimensional molecular crystals of ammonia dihydrate, the NH3−H2O−CH4 mixture, and two-dimensional layered ices revealed a series of energetically quasidegenerate structures with diverse crystal packing motifs. This method expands the scope and utility of molecular building blocks for designing stable molecular crystals, providing a robust framework for achieving extensive tunability in molecular materials design.

关键词： Molecular crystals

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Film cooling effectiveness in the presence of internal hole random roughness: A comprehensive analysis

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International Communications in Heat and Mass Transfer 2025年 165卷

作者： Wang, Xinyu Ye, Lin Li, Wei Zheng, Tianyi Liang, Xiyuan Liu, Cunliang School of Power and Energy Northwestern Polytechnical University Shaanxi Xi'an710129 China State Key Laboratory for Strength and Vibration of Mechanical Structures Xi'an Jiaotong University Shaanxi Xi'an710049 China Science and Technology on Altitude Simulation Laboratory Sichuan Mianyang621000 China Hunan Aviation Powerplant Research Institute Aero Engine Corporation of China Hunan Zhuzhou412002 China

Film cooling, with its excellent cooling performance, is widely applied in the active thermal protection design of aerospace propulsion systems. However, during manufacturing and service, film holes are affected by drilling processes and particle deposition, leading to significant deviations between the actual cooling structures and the original design. These deviations primarily manifest as hole blockage and increased surface roughness, which may cause cooling degradation. Therefore, it is essential to investigate the film cooling performance under structural damage and the jet-mainstream mixing mechanisms of damaged holes. This study focuses on internal roughness as a form of structural damage by investigating three levels of hole roughness—Ra = 3.1 μm (Film hole I), Ra = 35.9 μm (Film hole II), and Ra = 64.9 μm (Film hole III). The selected roughness levels and blowing ratios correspond to the practical range encountered in turbine cooling. The film cooling effectiveness distribution is measured using pressure-sensitive paint technology, and numerical simulations are conducted to analyze the flow field and support the experimental results. The results indicate that cooling degradation caused by internal roughness is mainly reflected in the reduction of high cooling effectiveness areas and the deterioration of cooling performance near the film hole exit. However, increased roughness also leads to an expansion of the film coverage in the spanwise, enhancing cooling performance downstream. Flow field analysis reveals that internal roughness increases the inhomogeneity of coolant velocity distribution inside the hole, strengthening the counter-rotating vortex pair and causing jet lift-off, which reduces the high cooling effectiveness area. Additionally, roughness-induced disturbances enhance turbulence intensity, promoting jet-mainstream mixing and increasing the overall film coverage. © 2025

关键词： Solar sails

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Multi-interface modification induced crack deflection behavior and enhanced fracture resistance in thermal barrier coatings

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Journal of Alloys and Compounds 2025年 1031卷

作者： Li, Qicheng Cui, Xiufang Jing, Yongzhi Xu, Wei Wang, Yi Chen, Zhuo Zhang, Zhijia Fang, Yongchao Shang, Tong Jin, Guo Institute of Surface/Interface Science and Technology Key Laboratory of Superlight Material and Surface Technology of Ministry of Education College of Material Science and Chemical Engineering Harbin Engineering University Harbin150001 China Northwest Institute for Nonferrous Metal Research Xi an710016 China The Military Industry Program Evaluation Center of Costind of SASTIND Beijing100048 China No.703 Research Institute China State Shipbuilding Co. Ltd Harbin150078 China Aviation Key Laboratory of Science and Technology on Advanced Corrosion and Protection for Aviation Material Beijing Beijing Institute of Aeronautical Materials Beijing100095 China

Conventional thermal barrier coatings (TBCs) composed of yttria-stabilized zirconia (YSZ) ceramic top layers and MCrAlY (M = Ni, Co, or their combination) alloy bond coats are prone to brittle fracture and interfacial delamination under extreme thermo-mechanical-chemical coupled *** study develops a composite-toughened thermal barrier coating (TBC) system integrating three innovations: laser-modified SiC whisker-reinforced YSZ-WL ceramic layers, a novel NiCoCrFeAl0.8Si0.1(NbMoTaW)0.1 high-entropy alloy bond coat, and hoop-patterned laser-textured interfaces. Compared to conventional TBC1 (NiCoCrAlY/YSZ), the optimized TBC3 demonstrates 64.3 % higher interfacial strength, survives 150 thermal shock cycles at 1100°C (20 % spallation area), and shows 61.43 % lower erosion mass loss post-thermal cycling. The YSZ-WL layer reduces cyclic molten salt corrosion mass loss by 22.58 % versus *** advancements highlight the synergistic effects of whisker toughening (crack deflection/bridging), high-entropy alloy bond coats (suppressed TGO growth), and hoop-textured interfaces (guided crack propagation), establishing a groundbreaking strategy for extreme-environment TBC applications. © 2025 Elsevier B.V.

关键词： Brittle fracture

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Direct Evidence of the Relationship between Piezoelectricity and Catalytic Activity

SSRN

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SSRN 2025年

作者： Gao, Wenpeng Zheng, Huashan Luo, Huajie Zhang, Haibo Jo, Wook Xie, Bing School of Power and Energy Jiangxi Key Laboratory of Green General Aviation Power Nanchang Hangkong University Nanchang330063 China Functional Materials and Acousto-optic Instruments Institute School of Instrumentation Science and Engineering Harbin Institute of Technology Harbin150080 China School of Materials Science and Engineering University of Science and Technology Beijing Beijing100083 China School of Materials Science and Engineering Huazhong University of Science and Technology Wuhan430074 China Ulsan44919 Korea Republic of Beijing Advanced Innovation Center for Materials Genome Engineering China State Key Laboratory of Material Processing and Die & Mould Technology China School of Materials Science and Engineering

Piezocatalysis is highly valued for its efficient energy conversion and environmental capabilities. However, the fundamental connection between piezoelectricity and piezocatalytic activity remains to be thoroughly investigated. Herein, piezoceramic thin flakes with varying levels of piezoelectricity were examined to quantitatively assess the impact of the piezoelectric coefficient (d33) on the piezocatalytic activation in energy and environment applications. The piezoceramic flake, 220 μm thick, possessing the highest piezoelectricity (d33 = 1100 pC/N), demonstrated the highest H2O2 yield (572 μM h-1) and the fastest degradation rate (k = 0.0725 min-1) of Rhodamine B (RhB), exceeding the best performance of previously reported ceramic blocks. In contrast, the same thickness flake with the lowest piezoelectricity (d33 = 150 pC/N) exhibited the weakest piezocatalytic performance. By analyzing internal carrier characteristics and simulating carrier migration pathways under an electric field, a quantitative relationship between piezoelectricity and piezocatalytic activity was established. The piezoceramic flake with higher piezoelectricity demonstrated a higher effective free carrier concentration, a larger number of transiently migrating carriers, and a shorter migration distance due to a stronger built-in electric field, resulting in enhanced piezocatalytic activity. This work clearly elucidates the relationship between piezoelectricity and piezocatalytic activity. © 2025, The Authors. All rights reserved.

关键词： Piezoelectricity

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Observation of molecular and polymeric nitrogen stuffed NaCl ionic layers

arXiv

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arXiv 2025年

作者： Ning, Ping Tian, Yifan Liu, Guangtao Wang, Hongbo Hu, Qingyang Liu, Hanyu Zhou, Mi Ma, Yanming Key Laboratory of Material Simulation Methods and Software Ministry of Education College of Physics Jilin University Changchun130012 China State Key Laboratory of Superhard Materials College of Physics Jilin University Changchun130012 China Center for High Pressure Science and Technology Advanced Research Beijing100094 China International Center of Future Science Jilin University Changchun130012 China

Sodium chloride (NaCl), a ubiquitous and chemically stable compound, has been considered inert under ambient conditions. Its typical B1 structure is highly isotropic without preferential direction, favoring the growth of a three-dimensional network of strong Na-Cl ionic bonds. Here, we employ first-principles structural searching and synchrotron X-ray diffraction to unravel an unexpected chemical reaction between NaCl and N2 to produce a hybrid salt-NaCl(N2)2, where N2 molecules break the isotropic NaCl structure into two-dimensional layers upon synthesis at 50 GPa. In contrast to the insulating properties of pristine NaCl, the electronic bandgap of the N2-stuffed NaCl narrowed to 1.8 eV, becoming an indirect bandgap semiconductor. Further compression to 130 GPa induced the polymerization of N atoms into zigzag N-chains. Our findings not only demonstrate the possibility of unusual N-chemistry under extreme conditions, but also suggest a feasible approach for the design of layered NaCl frameworks to modulate the polymerization of nitrogen. Copyright © 2025, The Authors. All rights reserved.

关键词： Sodium chloride

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First-principles study on Pr-doped Bilayer Nickelate La3Ni2O7

arXiv

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arXiv 2025年

作者： Huo, Zihao Zhang, Peng Shi, Haoliang Yan, Xiaochun Duan, Defang Cui, Tian Key Laboratory of Material Simulation Methods & Software of Ministry of Education State Key Laboratory of Superhard Materials College of Physics Jilin University Changchun130012 China MOE Key Laboratory for Non-equilibrium Synthesis and Modulation of Condensed Matter Shaanxi Province Key Laboratory of Advanced Functional Materials and Mesoscopic Physics School of Physics Xi’an Jiaotong University Xi’an710049 China Institute of High Pressure Physics School of Physical Science and Technology Ningbo University Ningbo315211 China

Recently, the Pr-doped Ruddlesden-Popper phase of bilayer nickelate La3Ni2O7 has been reported to exhibit a superconducting transition temperature (Tc) of 82.5 K and superconducting volume fraction of about 57 % at high pressure. However, the effect of Pr-doping on La3Ni2O7 remains unclear. Here, we studied the crystal structures and electronic properties of Pr-doped La3Ni2O7 at 0 and 15 GPa based on the first-principles calculations to explore the doping effect of Pr. Our findings indicate that the praseodymium atoms prefer to occupy the outer La-O layers site. We then investigated the evolution of crystal structures in both the ambient pressure phase and high pressure phase of La3Ni2O7 as a function of doping concentration, revealing inconsistent trends in their evolution with increasing doping levels. Finally, by fitting the bilayer two-orbital model, we propose that doping Pr may benefit for superconductivity of La3Ni2O7. These results not only can help the further experimental search of RP phase nickelate at lower pressure, but also provide helpful guide for understanding the effect of chemical pressure in isovalent doped RP phase nickelate superconductor. Copyright © 2025, The Authors. All rights reserved.

关键词： Superconducting transition temperature

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Omitted variable bias in single-pollutant epidemiological models for estimating long-term health effects of ambient fine particulate matter and ozone

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Journal of Hazardous Materials 2025年 494卷 138590页

作者： Xue, Tao Deng, Jianyu Ni, Xueqiu Kang, Ning Tong, Mingkun Li, Pengfei School of Public Health Peking University Health Science Centre Beijing100191 China Advanced Institute of Information Technology Peking University Hangzhou311215 China State Key Joint Laboratory of Environment Simulation and Pollution Control College of Environmental Sciences and Engineering Peking University Beijing100871 China Institute of Medical Technology Peking University Health Science Centre Beijing100191 China

Long-term exposure to PM2.5 and O3 is linked to various adverse health outcomes. However, many epidemiological studies on their health effects use single-pollutant models, leading to omitted variable bias (OVB). The percent bias, based on the classical OVB formula, depends on the PM2.5-O3 correlation and unobservable true effects. Data were sourced from two recent meta-analyses of the log-linear link between all-cause mortality and per-unit exposure to PM2.5 or O3. We then developed a new meta-regression method to correct biases, and its performance was verified through simulation. The OVB for PM2.5 or O3 can vary greatly from positive to negative across different spatial scales (like country, sub-national region, or city). By applying this method to 24 individual estimates, we found that a 10 μg/m³ increase in PM2.5 was linked to a 7.4 % increase in all-cause mortality risk, while O3’s association with all-cause mortality was not significant, which implies that PM2.5 must be considered in epidemiological analyses to obtain reliable effect estimates for O3. Our findings offer novel methodologies for the systematic assessment of the health effects of multiple pollutants. This contribution holds significant potential in fortifying health intervention strategies and minimizing the health risks posed by air pollution to the public. © 2025 Elsevier B.V.

关键词： Air quality

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Electrically Switchable Longitudinal Nonlinear Conductivity in Magnetic Semiconductors

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Physical Review Letters 2025年第4期134卷 046801-046801页

作者： Hong Jian Zhao Yuhao Fu Yurong Yang Yanchao Wang Laurent Bellaiche Yanming Ma Key Laboratory of Material Simulation Methods and Software of Ministry of Education College of Physics Jilin University Changchun 130012 China Key Laboratory of Physics and Technology for Advanced Batteries (Ministry of Education) College of Physics Jilin University Changchun 130012 China International Center of Future Science Jilin University Changchun 130012 China National Laboratory of Solid State Microstructures and Jiangsu Key Laboratory of Artificial Functional Materials Department of Materials Science and Engineering Nanjing University Nanjing 210093 China State Key Laboratory of Superhard Materials College of Physics Jilin University Changchun 130012 China Smart Functional Materials Center Physics Department and Institute for Nanoscience and Engineering University of Arkansas Fayetteville Arkansas 72701 USA Department of Materials Science and Engineering Tel Aviv University Ramat Aviv Tel Aviv 6997801 Israel

Writing data by electric field (as opposed to electric current) offers promises for energy efficient memory devices. While this data writing scheme is enabled by the magnetoelectric effect, the narrow spectrum of room-temperature magnetoelectrics hinders the design of practical magnetoelectric memories, and the exploration of other mechanisms toward low-power memories is greatly demanding. Here, we propose a mechanism that allows the electric-field writing of data beyond the framework of magnetoelectric effect. By symmetry analysis, we show that electric field can induce longitudinal nonlinear conductivity (LNC) in a wide spectrum of magnetic materials, including ferromagnets, antiferromagnets, magnetoelectrics, and nonmagnetoelectrics. The LNC is electrically switchable by reversing the electric field, where the switched LNC is detectable by transport measurements. Our first-principles simulations combined with transport calculations further predict YFeO3 and CuFeS2 (room-temperature antiferromagnets) to showcase electrically switchable LNC. Our Letter helps enrich the research avenues in nonlinear charge transport, and offers a pathway for designing energy efficient devices based on LNC.

关键词： Magnetoelectric effects

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