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High-temperature corrosion of sintered RE_(2)Si_(2)O_(7)(RE=Yb and Ho)environmental barrier coating materials by volcanic ash

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International Journal of Minerals,Metallurgy and Materials 2024年第7期31卷 1628-1638页

作者： Ayahisa Okawa Son Thanh Nguyen Tadachika Nakayama Thi-Mai-Dung Do Hisayuki Suematsu Shu Yin Takuya Hasegawa Tsuneo Suzuki Takashi Goto Koichi Niihara institute of Multidisciplinary research for Advanced Materials Tohoku UniversitySendai 980-8577Japan Department of Creative Engineering National Institute of TechnologyKushiro 084-0916Japan Extreme Energy-Density research institute Nagaoka University of TechnologyNagaoka 940-2188Japan Advanced institute for Materials research(WPI-AIMR) Tohoku UniversitySendai 980-8577Japan

Rare-earth silicates are promising environmental barrier coatings(EBCs)that can protect SiC_(f)/Si C_(m)substrates in next-genera tion gas turbine ***,RE_(2)Si_(2)O_(7)(RE=Yb and Ho)shows potential as an EBC due to its coefficient of thermal expansion(CTE)compatible with substrates and high resistance to water vapor *** target operating temperature for next-generation tur bine blades is 1400°*** is inevitable during adhesion to molten volcanic ash,and thus,understanding the corrosion behavior o the material is crucial to its *** study investigates the high-temperature corrosion behavior of sintered RE_(2)Si_(2)O_(7)(RE=Yb and Ho).Samples were prepared using a solid-state reaction and hot-press *** were then exposed to volcanic ash at 1400°C for 224,and 48 *** 48 h of exposure,volcanic ash did not react with Yb_(2)Si_(2)O_(7)but penetrated its interior,causing *** Ho_(2)Si_(2)O_(7)was partially dissolved in the molten volcanic ash,forming a reaction zone that prevented volcanic ash melts from penetrating the *** increasing heat treatment time,the reaction zone expanded,and the thickness of the acicular apatite grains increased The Ca:Si ratios in the residual volcanic ash were mostly unchanged for Yb_(2)Si_(2)O_(7)but decreased considerably over time for Ho_(2)Si_(2)O_(7).Th Ca in volcanic ash was consumed and formed apatite,indicating that RE^(3+)ions with large ionic radii(Ho>Yb)easily precipitated apatit from the volcanic ash.

关键词： environmental barrier coating volcanic ash rare-earth disilicate corrosion

Synergistic effect and heterointerface engineering of cobalt/carbon nanotubes enhancing electromagnetic wave absorbing properties of silicon carbide fibers

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Nano research 2024年第9期17卷 8479-8486页

作者： Zixiang Zhao Zheyipei Ma Zizhao Ding Yanqiong Liu Mingwei Zhang Chao Jiang institute of Powder Metallurgy research Central South UniversityChangsha 410083China

To improve the synergistic effect between dielectric and magnetic loss is a practical and effective way in optimizing electromagnetic wave absorbing *** composites of metal particles and carbon ligands derived from metal organic frameworks have gained wide *** this study,Co particles and multiwalled carbon nanotubes(CNT)were successfully synthesized covering the surface of silicon carbide(SiC)fibers,and the morphology,interfaces and electromagnetic wave absorption performance were *** sample SiC@Co/CNT,the minimum reflection loss value can reach-70.22 dB at 11.21 GHz with the thickness of 2.12 *** effective absorbing bandwidth can reach up to 6.03 GHz with the thickness of 1.71 mm,which covers the entire Ku *** brings more interfaces between Co particles and CNTs as well as SiC fibers and Co/C *** interfacial polarization has been hugely enhanced,and the microwave absorbing properties have been *** article reports on the impedance matching of magnetic and non-magnetic components and the heterointerface engineering,which can be effective strategy and inspiration to illustrate the relationship between components,structures and functions of electromagnetic wave absorbing materials.

关键词： metal organic frameworks Co nanocrystals carbon nanotubes Schottky heterointerfaces synergistic effect

Kinetics of dense plasma in the field of short laser pulses:A generalized approach

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Matter and Radiation at Extremes 2024年第5期9卷 87-92页

作者： V.A.Astapenko V.S.Lisitsa Moscow institute of Physics and Technology(National research university) Institutskii per.9141701 DolgoprudnyiRussia National research Centre“Kurchatov institute ”123182 MoscowRussia National research Nuclear university MEPhI 115409 MoscowRussia

A generalized kinetic model of atomic level populations in an optically dense plasma excited by laser pulses of arbitrary duration is formulated and *** model is based on a nonstationary expression for the probability of excitation of an atomic transition and takes into account the effects of laser pulse penetration into an optically dense medium.A universal formula for the excitation probability as a function of time and propagation length is derived and applied to the case of a Lorentzian spectral profile of an atomic transition excited by a laser pulse with a Gaussian *** features of nonstationary excitation probabilities are presented for different optical depths of the plasma,laser pulse durations,and carrier *** formulas derived here will be useful for the description of atomic populations excited by laser pulses under realistic conditions of dense plasmas.

关键词： laser excitation excited

Spatial and temporal variation of water clarity in typical reservoirs in the Beijing-Tianjin-Hebei region observed by GF 1-WFV satellite data

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Journal of Oceanology and Limnology 2024年第4期42卷 1048-1060页

作者： Chang CAO Junsheng LI Xiaodong JIA Shenglei WANG Bo WAN Liaoning earthquake Agency Shenyang 11000China Key Laboratory of Digital Earth Science Aerospace Information Research InstituteChinese Academy of SciencesBeijing 100094China International research Center of Big Data for Sustainable Development Goals Beijing 100094China School of Electronic Electrical and Communication EngineeringUniversity of Chinese Academy of SciencesBeijing 100049China

Rapidly monitoring regional water quality and the changing trend is of great practical and scientific significance,especially for the Beijing-Tianjin-Hebei(BTH)region of China where water resources are relatively scarce and inland water bodies are generally *** remote sensing data of the GF 1 satellite launched in 2013 have characteristics of high spatial and temporal resolution,which can be used for the dynamic monitoring of the water environment in small lakes and ***,the water quality remote sensing monitoring model based on the GF 1 satellite data for lakes and reservoirs in BTH is still lacking because of the considerable differences in the optical characteristics of the lakes and *** this paper,the typical reservoirs in BTH-Guanting Reservoir,Yuqiao Reservoir,Panjiakou Reservoir,and Daheiting Reservoir are taken as the study *** the atmospheric correction of GF 1-WFV,the relative radiation normalized atmospheric correction was adopted after comparing it with other methods,such as 6 S and *** the water clarity retrieval,a water color hue angle based model was proposed and outperformed other available published models,with the R 2 of 0.74 and MRE of 31.7%.The clarity products of the four typical reservoirs in the BTH region in 2013-2019 were produced using the GF 1-WFV *** on the products,temporal and spatial changes in clarity were analyzed,and the main influencing factors for each water body were *** was found that the clarity of Guanting,Daheiting,and Panjiakou reservoirs showed an upward trend during this period,while that of Yuqiao Reservoir showed a downward *** the influencing factors,the water level of the water bodies can be an important factor related to the water clarity changes in this region.

关键词： GF 1 satellite atmospheric correction clarity Beijing-Tianjin-Hebei spatial and temporal change analysis

Defect Engineering in Earth-Abundant Cu2ZnSnSe4 Absorber Using Efficient Alkali Doping for Flexible and Tandem Solar Cell Applications

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Energy & Environmental Materials 2024年第2期7卷 253-260页

作者： Muhammad Rehan Ara Cho Inyoung Jeong Kihwan Kim Asmat Ullah Jun-Sik Cho Joo Hyung Park Yunae Jo Sung Jun Hong Seung Kyu Ahn SeJin Ahn Jae Ho Yun Jihye Gwak Donghyeop Shin Photovoltaics research Department Korea Institute of Energy Research (KIER) Department of Renewable Energy Engineering University of Science and Technology (UST) Korea institute of Energy Technology (KENTECH)

To demonstrate flexible and tandem device applications, a low-temperature Cu2ZnSnSe4（CZTSe） deposition process, combined with efficient alkali doping, was developed. First, high-quality CZTSe films were grown at480 °C by a single co-evaporation, which is applicable to polyimide（PI）substrate. Because of the alkali-free substrate, Na and K alkali doping were systematically studied and optimized to precisely control the alkali distribution in CZTSe. The bulk defect density was significantly reduced by suppression of deep acceptor states after the（Na F + KF） PDTs. Through the low-temperature deposition with（Na F + KF） PDTs, the CZTSe device on glass yields the best efficiency of 8.1% with an improved VOCdeficit of646 m V. The developed deposition technologies have been applied to *** the first time, we report the highest efficiency of 6.92% for flexible CZTSe solar cells on PI. Additionally, CZTSe devices were utilized as bottom cells to fabricate four-terminal CZTSe/perovskite tandem cells because of a low bandgap of CZTSe（～1.0 e V） so that the tandem cell yielded an efficiency of 20%. The obtained results show that CZTSe solar cells prepared by a low-temperature process with in-situ alkali doping can be utilized for flexible thin-film solar cells as well as tandem device applications.

关键词： alkali doping Earth-abundant Cu2ZnSnSe4 flexible solar cells four-terminal tandem cells low-temperature process

Efficient simulation of spatially correlated non-stationary ground motions by wavelet-packet algorithm and spectral representation method

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earthquake Engineering and Engineering Vibration 2024年第04期 799-814页

作者： Ji Kun Cao Xuyang Wang Suyang Wen Ruizhi College of Civil and Transportation Engineering Hohai University The Key Laboratory of Urban Security and Disaster Engineering of Ministry of Education Beijing University of Technology Key Laboratory of earthquake Engineering and Engineering Vibration Institute of Engineering MechanicsChina Earthquake Administration Key Laboratory of earthquake Disaster Mitigation Ministry of Emergency Management

Although the classical spectral representation method(SRM) has been widely used in the generation of spatially varying ground motions, there are still challenges in efficient simulation of the non-stationary stochastic vector process in practice. The first problem is the inherent limitation and inflexibility of the deterministic time/frequency modulation function. Another difficulty is the estimation of evolutionary power spectral density(EPSD) with quite a few samples. To tackle these problems, the wavelet packet transform(WPT) algorithm is utilized to build a time-varying spectrum of seed recording which describes the energy distribution in the time-frequency domain. The time-varying spectrum is proven to preserve the time and frequency marginal property as theoretical EPSD will do for the stationary process. For the simulation of spatially varying ground motions, the auto-EPSD for all locations is directly estimated using the time-varying spectrum of seed recording rather than matching predefined EPSD models. Then the constructed spectral matrix is incorporated in SRM to simulate spatially varying non-stationary ground motions using efficient Cholesky decomposition techniques. In addition to a good match with the target coherency model, two numerical examples indicate that the generated time histories retain the physical properties of the prescribed seed recording, including waveform, temporal/spectral non-stationarity, normalized energy buildup, and significant duration.

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Migratory mode transition of astrocyte progenitors in the cerebral cortex: an intrinsic or extrinsic cell process?

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Neural Regeneration research 2024年第3期19卷 471-472页

作者： Michio Miyajima Hidenori Tabata Kazunori Nakajima Department of Anatomy Keio University School of MedicineShinjuku-kuTokyoJapan Department of Molecular Neurobiology Institute for Developmental ResearchAichi Developmental Disability CenterKasugaiAichiJapan

The cerebral cortex is comprised of properly localized cell types that exert their specific *** the developing brain,cells migrate from the germinal region to their functional locations(Silva et al.,2019;Cossart and Garel,2022).For example,neocortical excitatory neurons are generated in the cerebral ventricular and subventricular zones,move to the developing cortical plate via radial migration,and reside in a radial array of six neuronal layers(Oishi and Nakajima,2018).On the other hand,cortical interneurons are mainly generated in ganglionic eminences,migrate tangentially across the cerebral cortex,and reach their final destinations in the cortex(Lim et al.,2018).The failure of neuronal migration leads to defects in cortical layer *** the mechanisms of neuronal distribution have been well examined,how astrocytes are diffusely distributed in the cortex is still *** are glial cells in the cerebral cortex with several functions,including metabolic support and synapse formation(Abbott et al.,2006;Bosworth and Allen,2017;Allen and Lyons,2018).For example,astrocytes establish synaptic connectivity in the developing brain while they contact numerous synapses and maintain optimal neuronal activity in the adult *** the developing brain,astrocytes are primarily generated from radial glia after the neurogenic *** a certain type of astrocyte called fibrous astrocytes populates the white matter,protoplasmic astrocytes migrate to the cortical plate during neural network formation.

关键词： cerebral migrate Abbott

A compact route for efficient production of high-purity β-Ga2O3 powder

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Rare Metals 2024年第9期43卷 4573-4584页

作者： Xiao-Wei Zhou Gao-Jie Chen Liang Xu Zhi-Jun Shao Cheng Yang Yong-Pan Tian Zhuo Zhao School of Metallurgical Engineering Anhui University of Technology Low-Carbon research institute Anhui University of Technology

The present study has proposed a compact process for the production of high-purity β-Ga2O3powder by simply using gallium metal and water as the raw materials. The process basically consists of two essential steps including hydrothermal synthesis of Ga OOH and calcination of Ga OOH for the production of the target product of β-Ga2O3. Thermodynamic evaluation and systematic experiments were conducted for process parameter optimization. X-ray diffractometer（XRD）, scanning electron microscopy（SEM）, thermogravimetryDdifferential scanning calorimetry（TG-DSC） and X-ray photoelectron spectroscopy（XPS） were utilized to clarify the reaction mechanisms of the hydrothermal synthesis and transformation of Ga OOH to β-Ga2O3by calcination. Chemical analysis of the final product of β-Ga2O3obtained under the optimal conditions was carried out with inductively coupled plasma mass spectrometry（ICP-MS）, and the results showed that the contents of the representative impurities such as Ni, Cu, In, Mn, Co, Zn and Cr are obviously lower than the requirement of 5N β-Ga2O3standard, exhibiting excellent application prospect of the proposed process to produce high-purity β-Ga2O3.

关键词： Calcination Hydrothermal synthesis Purity Reaction mechanism β-Ga2O3

The accessible seismological dataset of a high-density 2D seismic array along Anninghe fault

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earthquake Science 2024年第1期37卷 67-77页

作者： Weifan Lu Zeyan Zhao Han Yue Shiyong Zhou Jianping Wu Xiaodong Song School of Earth and Space Sciences Peking UniversityBeijing 100871China institute of Geophysics China Earthquake AdministrationBeijing 100081China

The scientific goal of the Anninghe seismic array is to investigate the detailed geometry of the Anninghe fault and the velocity structure of the fault *** 2D seismic array is composed of 161 stations forming sub-rectangular geometry along the Anninghe fault,which covers 50 km and 150 km in the fault normal and strike directions,respectively,with~5 km *** data were collected between June 2020 and June 2021,with some level of temporal *** types of instruments,***-05A and SmartSolo,are used in this *** quality and examples of seismograms are provided in this *** the data protection period ends(expected in June 2024),researchers can request a dataset from the National earthquake Science Data Center.

关键词： Anninghe fault seismological dataset data share