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Effects of air damping on quality factors of different probes in tapping mode atomic force microscopy

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Chinese Physics B 2024年第9期33卷 506-519页

作者： Yu zeng Guo-Lin Liu Jin-Hao Liu zheng wei School of Mechanical and Electrical Engineering Beijing University of Chemical TechnologyBeijing 100029China

The AFM probe in tapping mode is a continuous process of energy dissipation,from moving away from to intermittent contact with the sample *** present,studies regarding the energy dissipation mechanism of this continuous process have only been reported sporadically,and there are no systematic explanations or experimental verifications of the energy dissipation mechanism in each stage of the continuous *** quality factors can be used to characterize the energy dissipation in TM-AFM *** this study,the vibration model of the microcantilever beam was established,coupling the vibration and damping effects of the microcantilever *** quality factor of the vibrating microcantilever beam under damping was derived,and the air viscous damping when the probe is away from the sample and the air squeeze film damping when the probe is close to the sample were *** addition,the mechanism of the damping effects of different shapes of probes at different tip–sample distances was *** accuracy of the theoretical simplified model was verified using both experimental and simulation methods.A clearer understanding of the kinetic characteristics and damping mechanism of the TM-AFM was achieved by examining the air damping dissipation mechanism of AFM probes in the tapping mode,which was very important for improving both the quality factor and the imaging quality of the TM-AFM *** study’s research findings also provided theoretical references and experimental methods for the future study of the energy dissipation mechanism of micro-nano-electromechanical systems.

关键词： TM-AFM quality factors air viscous damping air squeeze film damping

Investigation of improving the thermophysical properties and corrosion resistance of RE_(2)SiO_(5)/RE_(2)Si_(2)O_(7)multiphase silicates by component design with RE doping

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Journal of Advanced Ceramics 2024年第6期13卷 842-860页

作者： Zeyu Chen Yiling Huang Zhaoxuan Zhang wei zheng Xuemei Song Yaran Niu Yi zeng The State Key Lab of High Performance Ceramics and Superfine Microstructure Shanghai Institute of CeramicsChinese Academy of SciencesShanghai 200050China Center of Materials Science and Optoelectronics Engineering University of Chinese Academy of SciencesBeijing 100049China Key Laboratory of Inorganic Coating Materials CAS Shanghai Institute of CeramicsChinese Academy of SciencesShanghai 200050China

In this research,a novel method for regulating components in RE_(2)SiO_(5)/RE_(2)Si_(2)O_(7)multiphase silicates was developed,combining the benefits of a suitable thermal expansion coefficient(CTE)and outstanding corrosion resistance against calcium–magnesium–alumino–silicate(CMAS).This approach enhanced the overall thermophysical ***,the results from the CMAS corrosion resistance test indicated that(Lu_(1/3)Yb_(1/3)Tm_(1/3))_(2)SiO_(5)/(Lu_(1/3)Yb_(1/3)Tm_(1/3))_(2)Si_(2)O_(7)and(Lu_(1/4)Yb_(1/4)Tm_(1/4)Er_(1/4))_(2)SiO_(5)/(Lu_(1/4)Yb_(1/4)Tm_(1/4)Er_(1/4))_(2)Si_(2)O_(7)exhibited exceptional resistance to CMAS penetration,even at temperatures up to 1500℃.To comprehend the corrosion mechanism of CMAS on these silicates,we introduced a reaction–diffusion model,which involved observing the changes in the interface between the corrosion product layer and the silicate *** was achieved using electron backscatter diffraction(EBSD).These findings lay a theoretical basis for selecting rare earth elements in RE_(2)SiO_(5)/RE_(2)Si_(2)O_(7)multiphase silicates based on the radii of different rare earth cations.

关键词： thermal conductivity environmental barrier coatings(EBCs) thermal expansion coefficient(CTE) multiphase silicates calcium-magnesium-alumino-silicate(CMAS)corrosion resistance reaction-diffusion

An experimental study of extracellular signal-regulated kinase and its interventional treatments in hepatic fibrosis

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Hepatobiliary & Pancreatic Diseases International 2008年第1期7卷 51-57页

作者： Jiang, Ming-De zheng, Shu-Mei Xu, Hui zeng, wei-zheng Zhang, Yong Sun, Hao-Ping Wang, Yun-Xia Qin, Jian-Ping Wu, Xiao-Ling Gen Hosp Chenghu Milt Command Dept Gastroenterol Chengdu 610083 Peoples R China

BACKGROUND: The pathogenesis of hepatic fibrosis and cirrhosis is still not fully understood. The extracellular signal-regulated kinase (ERK) pathway is involved in the regulation of cell proliferation and differentiation. The aim of this study was to investigate the effects of PD98059, a specific inhibitor of ERK, on the cell cycle, cell proliferation, secretion of type I collagen and expression of cyclin D1 mRNA, CDK4 mRNA and transforming growth factor-beta 1 (TGF-beta 1) mRNA in rat hepatic stellate cells (HSCs) stimulated by acetaldehyde. METHODS: Rat HSCs stimulated by acetaldehyde were incubated with PD98059 at different concentrations. The cell cycle was analysed by flow cytometry. Cell proliferation was assessed by the methyl thiazolyl tetrazolium colorimetric assay. The mRNA expression of cyclin D1, CDK4 and TGF-beta 1 was examined using the reverse transcriptase-polymerase chain reaction. Type I collagen in the culture medium was detected by enzyme-linked immunosorbent assay. RESULTS: 20, 50 and 100 mu mol/L PD98059 significantly inhibited the proliferation and provoked a G0/G1-phase arrest of acetaldehyde-induced HSCs in a dose-dependent manner. The secretion of type I collagen and the expression of cyclin D1, CDK4 and TGF-beta 1 mRNA in acetaldehyde-induced HSCs were markedly inhibited by 50 and 100 mu mol/L PD98059, respectively. CONCLUSIONS: The ERK pathway regulates the cell proliferation, secretion of type I collagen and the expression of TGF-beta 1 mRNA in rat HSCs stimulated by acetaldehyde, which is likely related to its regulative effect on the cell cycle.

关键词： extracellular signal-regulated kinase hepatic stellate cell hepatic fibrosis

Elevating the comprehensive thermal properties of rare-earth cerates through high-entropy design

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Journal of Materiomics 2024年第5期10卷 1126-1136页

作者： Zhaoxuan Zhang Yiling Huang Fan Peng wei zheng Caifen Jiang Xuemei Song Yi zeng School of Microelectronics Shanghai UniversityShanghai201800China The State Key Lab of High Performance Ceramics and Superfine Microstructure Shanghai Institute of CeramicsChinese Academy of ScienceShanghai200050China

In the rapidly evolving aerospace sector,the quest for sophisticated thermal barrier coating(TBC)materials has *** materials are primarily sought for their superior comprehensive thermal characteristics,which include a low thermal conductivity coupled with a high coefficient of thermal expansion(CTE)that synergizes with the *** our study,we adopt a solid-state method to synthesize a series of high-entropy rare-earth cerates:La_(2)Ce_(2)O_(7)(1RC),(La_(1/2)Nd_(1/2))2Ce_(2)O_(7)(2RC),(La_(1/3)Nd_(1/3)Sm_(1/3))_(2)Ce_(2)O_(7)(3RC),(La_(1/4)Nd_(1/4)Sm_(1/4)Eu_(1/4))_(2)Ce_(2)O_(7)(4RC),and(La_(1/5)Nd_(1/5)Sm_(1/5)Eu_(1/5)Gd_(1/5))2Ce2O7(5RC),all sintered at 1,600℃ for 10 *** thoroughly examine their phase structure,morphology,elemental distribution,and thermal *** in-depth analysis of the phonon scattering mechanisms reveals that 4RC and 5RC exhibit exceptional thermal properties:high CTEs of 13.00×10^(−6) K^(−1) and 12.77×10^(−6) K^(−1) at 1,400℃,and low thermal conductivities of 1.55 W/(m·K)and 1.68 W/(m·K)at 1,000℃,*** to other TBC systems,4RC and 5RC stand out for their excellent thermal *** study significantly contributes to the development of high-entropy oxides for TBC applications.

关键词： Thermal barrier coatings(TBCs) Comprehensive thermal properties Coefficient of thermal expansion Thermal conductivity Phonon scattering mechanisms

Advances in multi-scale design and fabrication processes for thick electrodes in lithium-ion batteries

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Energy Reviews 2024年第2期3卷 14-30页

作者： Xiuxue Liu Yubin zeng wei Yuan Guanhua Zhang Huai zheng Zhongxue Chen Key Laboratory of Hydraulic Machinery Transients Ministry of EducationSchool of Power and Mechanical EngineeringWuhan UniversityWuhan430072China School of Mechanical and Automotive Engineering South China University of TechnologyGuangzhou510640GuangdongChina State Key Laboratory of Advanced Design and Manufacturing for Vehicle Body College of Mechanical and Vehicle EngineeringHunan UniversityChangsha410082China Greater Bay Area Institute for Innovation Hunan UniversityGuangzhou511300China

In the contemporary era,lithium-ion batteries have gained considerable attention in various industries such as 3C products,electric vehicles and energy storage systems due to their exceptional *** the rapid progress in the energy storage sector,there is a growing demand for greater energy density in lithium-ion *** the use of thick electrodes is a straightforward and effective approach to enhance the energy density of battery,it is hindered by the sluggish reaction dynamics and insufficient mechanical ***,we comprehensively review recent advances in the field of thick electrodes for lithium-ion batteries to overcome the bottlenecks in the development of thick electrodes and achieve efficient fabrication for high-performance lithium-ion ***,a systematic analysis is performed to identify the factors affecting the performance of the thick *** correlation between electrode materials,structural parameters,and performance is also ***,the viable strategies for constructing thick electrodes with improved properties are summarize,including high throughput,high conductivity and low tortuosity,in both material development and structural *** addition,recent advances in efficient fabrication methods for thick electrode fabrication are reviewed,with a comprehensive assessment of their merits,limitations,and applicable ***,a comprehensive overview of the multiscale design and manufacturing process for thick electrodes in lithium-ion batteries is provided,accompanied by valuable insights into design considerations that are crucial for future advances in this area.

关键词： Lithium-ion battery Thick electrode High energy density Electrode structure Multi-scale design Material development

On-surface synthesis and characterization of polyynic carbon chains

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National Science Review 2024年第3期11卷 192-199页

作者： Wenze Gao wei zheng Luye Sun Faming Kang zheng Zhou wei Xu Interdisciplinary Materials Research Center School of Materials Science and Engineering Tongji University

Carbyne, an elusive sp-hybridized linear carbon allotrope, has fascinated chemists and physicists for decades. Due to its high chemical reactivity and extreme instability, carbyne was much less explored in contrast to the sp2-hybridized carbon allotropes such as graphene. Herein, we report the on-surface synthesis of polyynic carbon chains by demetallization of organometallic polyynes on the Au（111） surface;the longest one observed consists of ～60 alkyne units（120 carbon atoms）. The polyynic structure of carbon chains with alternating triple and single bonds was unambiguously revealed by bond-resolved atomic force microscopy. Moreover, an atomically precise polyyne, C14, was successfully produced via tip-induced dehalogenation and ring-opening of the decachloroanthracene molecule(C14Cl10) on a bilayer NaCl/Au（111） surface at 4.7 K, and a band gap of 5.8 eV was measured by scanning tunnelling spectroscopy,in a good agreement with the theoretical HOMO–LUMO gap（5.48 eV）.

关键词： polyyne scanning probe microscopy carbon allotrope on-surface synthesis organometallic polyyne

Incidence and Mortality of Cancers in Female Genital Organs—China,2022

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China CDC weekly 2024年第10期6卷 195-202,I0003,I0004页

作者： Kexin Sun Bingfeng Han Hongmei zeng Shaoming Wang Li Li Ru Chen Rongshou zheng Wenqiang wei National Central Cancer Registry National Cancer Center/National Clinical Research Center for Cancer/Cancer HospitalChinese Academy of Medical Sciences and Peking Union Medical CollegeBeijingChina

Introduction:This study presented the incidence and mortality rates of cancers affecting the female genital organs in China,along with their trends spanning from 2010 to ***:700 population-based cancer registries provided relevant cancer incidence and mortality data for the year *** these,106 registries had continuous monitoring data suitable for trend analysis from 2010 to *** focused specifically on cancers affecting female genital organs(ICD10=C51-C54,C56)and projected their incidences and mortalities in China for 2022 based on data from 2018 and the trends observed from 2010 to ***-standardized incidence rate(ASIR)and mortality rate(ASMR)were calculated using Segi’s world standard ***:In 2022,there were an estimated 296,300 new cases and 104,900 deaths from female cancers in *** for vulva(C51),vagina(C52),cervix uteri(C53),corpus uteri(C54),and ovary(C56)were 0.32,0.23,13.83,6.84,and 5.68 per 100,000 *** for corpus uteri and ovary cancers were higher in urban *** for vulva,vagina,cervix,corpus uteri,and ovary cancers were 0.14,0.08,4.54,1.05,and 2.64 per 100,000 population,*** for ovarian cancer was higher in urban *** and ASMRs for most female genital organ cancers increased from 2010 to 2018,although the rate of increase for vulvar and cervical cancers in rural areas has slowed ***:Tailored cancer prevention and control programs specific to each region are necessary to address the growing disease burden.

关键词： ICD10 mortality organs

Accurately tracking hypersonic gliding vehicles via an LEO mega-constellation in relay tracking mode

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Journal of Systems Engineering and Electronics 2024年第1期35卷 211-221页

作者： LI Zhao WANG Yidi zheng wei College of Aerospace Science and Engineering National University of Defense TechnologyChangsha 410073China

In order to effectively defend against the threats of the hypersonic gliding vehicles(HGVs),HGVs should be tracked as early as possible,which is beyond the capability of the ground-based *** benefited by the developing megaconstellations in low-Earth orbit,this paper proposes a relay tracking mode to track HGVs to overcome the above *** whole tracking mission is composed of several tracking intervals with the same *** each tracking interval,several appropriate satellites are dispatched to track the *** that are planned to take part in the tracking mission are selected by a new derived observability *** tracking performances of the proposed tracking mode and the other two traditional tracking modes,including the stare and track-rate modes,are compared by *** results show that the relay tracking mode can track the whole trajectory of a HGV,while the stare mode can only provide a very short tracking ***,the relay tracking mode achieve higher tracking accuracy with fewer attitude controls than the track-rate mode.

关键词： target tracking mega-constellation hypersonic gliding vehicle(HGV) sensor selection observability analysis

Improving the spaceborne GNSS-R altimetric precision based on the novel multilayer feedforward neural network weighted joint prediction model

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Defence Technology（防务技术） 2024年第2期32卷 271-284页

作者： Yiwen Zhang wei zheng Zongqiang Liu Qian Xuesen Laboratory of Space Technology China Academy of Space TechnologyBeijing 100094China China Academy of Aerospace Science and Innovation Beijing 100176China State Key Laboratory of Space-Ground Integrated Information Technology Beijing Institute of Satellite Information EngineeringBeijing 100194China

Global navigation satellite system-reflection(GNSS-R)sea surface altimetry based on satellite constellation platforms has become a new research direction and inevitable trend,which can meet the altimetric precision at the global scale required for underwater *** present,there are still research gaps for GNSS-R altimetry under this mode,and its altimetric capability cannot be specifically ***,GNSS-R satellite constellations that meet the global altimetry needs to be ***,the matching precision prediction model needs to be established to quantitatively predict the GNSS-R constellation altimetric ***,the GNSS-R constellations altimetric precision under different configuration parameters is calculated,and the mechanism of the influence of orbital altitude,orbital inclination,number of satellites and simulation period on the precision is analyzed,and a new multilayer feedforward neural network weighted joint prediction model is ***,the fit of the prediction model is verified and the performance capability of the model is tested by calculating the R2 value of the model as 0.9972 and the root mean square error(RMSE)as 0.0022,which indicates that the prediction capability of the model is ***,using the novel multilayer feedforward neural network weighted joint prediction model,and considering the research results and realistic costs,it is proposed that when the constellation is set to an orbital altitude of 500 km,orbital inclination of 75and the number of satellites is 6,the altimetry precision can reach 0.0732 m within one year simulation period,which can meet the requirements of underwater navigation precision,and thus can provide a reference basis for subsequent research on spaceborne GNSS-R sea surface altimetry.

关键词： GNSS-R satellite constellations Sea surface altimetric precision Underwater navigation Multilayer feedforward neural network