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Characteristics of orthorhombic anisotropic seismic response induced by horizontal in situ stress in vertical transversely isotropic media

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Science China Earth Sciences 2024年第7期67卷 2291-2310页

作者： Xinpeng PAN Chengxu lu Zhizhe ZHAO Jianxin liu School of Geoscience and Info-Physics Central South UniversityChangsha 410083China Hunan Key Labraory of Nonferrous Resources and Geological Disaster Exploration Central South University Changsha 410083China Key Laboratory of Metallogenic Prediction of Nonferrous Metals and Geological Environment Monitoring(Central South University) Ministry of EducationChangsha 410083China PowerChina Zhongnan Engineering Corporation Limited Changsha 410014China

Sedimentary strata typically exhibit the characteristics of transverse isotropy(VTI)with a vertical axis of ***,fractures in sedimentary strata tend to produce anisotropic closure due to horizontal in situ stress,resulting in pronounced orthorhombic anisotropy in VTI media under such stress conditions and influencing the propagation behavior of seismic *** studies have primarily focused on the elastic wave velocity anisotropy induced by applied stress in isotropic background media,neglecting the impact of VTI background media on the anisotropy induced by horizontal in situ stress and the response characteristics of seismic wave *** address these gaps,we first establish the effective elastic stiffness tensor of VTI media under horizontal in situ stress using nonlinear acoustoelastic ***,we derive the accurate and linearized approximate equations for P-wave seismic reflectivity of VTI media under horizontal in situ stress,based on wave equations and scattering theory,***,we compare and analyze the characteristics of orthorhombic anisotropic seismic response induced by horizontal in situ stress at various types of elastic reflection *** results demonstrate that the linearized approximation of the seismic reflection response characteristics closely aligns with the accurate equations under conditions of small stress below 10 MPa,effectively capturing the azimuth-dependent orthorhombic anisotropy induced by horizontal in situ stress in VTI *** results of this study also provide a novel theoretical approach and valuable insights into the seismic prediction of in situ stress.

关键词： Horizontal in situ stress Nonlinear acoustoelastic theory Linear slip theory Orthorhombic anisotropy Stress seismic prediction

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Recent Advances in Biomass-derived Porous Carbon Materials:Synthesis,Composition and Applications

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Chemical Research in Chinese Universities 2024年第1期40卷 3-19页

作者： ZHAI Ziqi lu Yumiao liu Guangyong DING Wei-lu CAO Bobo HE Hongyan CAS Key Laboratory of Green Process and Engineering State Key Laboratory of Mesoscience and EngineeringBeijing Key Laboratory of Ionic Liquids Clean ProcessInstitute of Process EngineeringChinese Academy of SciencesBeijing 100190P.R.China University of Chinese Academy of Sciences Beijing 100049P.R.China Longzihu New Energy Laboratory Zhengzhou Institute of Emerging Industrial TechnologyZhengzhou 450000P.R.China

Porous carbon materials(PCMs)play a pivotal role in diverse applications,such as energy storage,adsorption,catalysis,environmental remediation,and microwave *** selection of carbon precursors,in particular,is crucial for tailoring porous structures with specific ***,with its rich carbon feedstock,abundant availability,renewability,and versatile structures,has emerged as a promising precursor for porous carbon material *** review comprehensively summarizes the recent advances in biomass-derived porous carbon materials(BPCMs)encompassing synthetic strategy,morphology,structural composition,and multiple *** first review synthetic approaches aiming at regulating porosity,followed by morphological and composition features of BPCMs,with a special emphasis on elucidating the dimensional clarification and heteroatom doping *** discussion then extends to the wide-ranging applications of BPCMs,covering energy-related applications and CO_(2) adsorption to environmental ***,the review outlines the existing challenges and prospects in the *** summary,this review systematically describes BPCMs and provides valuable guidance for researchers to select and synthesize BPCMs that meet specific functional requirements.

关键词： Biomass Porous carbon Pyrolysis Heteroatom-doping Supercapacitor CO_(2)adsorption

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Preparation of Polyurea Elastomer with Flame Retardant, Insulation and Thermal Conductivity Properties

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Journal of Wuhan University of Technology(Materials Science) 2024年第3期39卷 781-789页

作者：方今 DONG Yang lu Shangkai liu Junbang AI Lianghui 刘平 State Key Laboratory of luminescent Materials and Devices Research Institute of Materials ScienceSouth China University of TechnologyGuangzhou 510640China

By using 6,6-((sulfonylbis(4,1-phenylene)bis(azanediyl))bis(thiophen-2-ylm-ethylene))bis6H-di-benzo[c,e][1,2]oxaphosphinine 6-oxide(DOPO-N)as phosphorus-nitrogen flame retardant,the polyurea(PUA)with flame retardant properties(PUA/DOPO-N)was *** addition,organically modified montmorillonite(OMMT)and magnesium hydroxide(MH)were used as co-effectors respectively,and the flame retardant PUA(PUA/DOPO-N/OMMT and PUA/DOPO-N/MH)were also *** properties,flame retardant properties,flame retardant mechanism and mechanical properties of PUA/DOPO-N,PUA/DOPO-N/OMMT and PUA/DOPO-N/MH were investigated by thermogravimetric(TG)analysis,limiting oxygen index(LOI),UL 94,cone calorimeter test,scanning electron microscopy(SEM),and tensile *** results show that the LOI value of PUA/20%DOPO-N,PUA/18%DOPO-N/2%OMMT and PUA/15%DOPO-N/5%MH are 27.1%,27.7%,and 28.3%,respectively,and UL 94 V-0 rating is *** with PUA,the peak heat release rate(pk-HRR),total heat release(THR)and average effective heat combustion(av-EHC)of PUA/20%DOPO-N,PUA/18%DOPO-N/2%OMMT and PUA/15%DOPO-N/5%MH decrease *** results indicate that the residual chars of PUA/20%DOPO-N,PUA/18%DOPO-N/2%OMMT and PUA/15%DOPO-N/5%MH are completer and more *** complex of DOPO-N/OMMT and DOPO-N/MH have synergistic flame *** mechanical properties of PUA can be improved by the addition of DOPO-N,DOPO-N/OMMT and DOPO-N/MH,*** insulation performance test shows that the volume resistivity of PUA/20%DOPO-N is 6.25×10^(16)Ω.***,by using modified boron nitride(MBN)as heat dissipating material,the complex of PUA/MBN was prepared,and the thermal conductivity of PUA/MBN was *** thermal conductivity of PUA/8%MBN complex coating at room temperature is 0.166 W/(M·K),which is a 163%improvement over pure PUA.

关键词： polyurea organic flame retardant inorganic flame retardant synergistic flame retardancy insulation thermal conductivity

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Elucidating the enhancement of kaolinite flotation by iron content through density functional theory: A study on sodium oleate adsorption efficiency

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International Journal of Mining Science and Technology 2024年第6期34卷 855-866页

作者： Lingyun liu Chuilei Kong Hongyu Zhao Fangqin lu Joint National-Local Engineering Research Centre for Safe and Precise Coal Mining Huainan 232001China Department of Materials Science and Engineering Anhui University of Science and TechnologyHuainan 232001China School of Civil and Resource Engineering University of Science and Technology BeijingBeijing 100083China

This study delves into the intricate relationship between iron(Fe)content in kaolinite and its impact on the adsorption behavior of sodium *** effects of different iron concentrations on adsorption energy,hydrogen bond kinetics and adsorption efficiency were studied through simulation and experimental *** results show that the presence of iron in the kaolinite structure significantly improves the adsorption capacity of sodium *** samples with high iron content have better adsorption properties,lower adsorption energy levels and shorter and stronger hydrogen bonds than pure *** optimal concentration of oleic acid ions for achieving maximum adsorption efficiency was identified as 1.2 mmol/L across different kaolinite *** this concentration,the adsorption rates and capacities reach their peak,with Fe-enriched kaolinite samples exhibiting notably higher flotation recovery *** optimal concentration represents a balance between sufficient oleic acid ion availability for surface interactions and the prevention of self-aggregation phenomena that could hinder *** study offers promising avenues for optimizing the flotation process in mineral processing applications.

关键词： Iron Influence Sodium Oleate Adsorption Kaolinite Surfaces Molecular Interaction Analysis Flotation Efficiency Optimization

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Weighted Composition Operators That Preserve Frames On Weighted Hardy Spaces

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Acta Mathematica Sinica,English Series 2024年第7期40卷 1645-1654页

作者： Ya Li Dong Rui liu Guo Xiang lu School of Mathematical Sciences and LPMC Nankai UniversityTianjin300071P.R.China School of Statistics and Mathematics Zhongnan University of Economics and LawWuhan430073P.R.China

In this paper, we characterize weighted composition operators that preserve frames on the weighted Hardy spaces in the unit disk. In particular, we obtain the symbol properties of the bounded invertible weighted composition operators. Moreover, we establish the equivalence between bounded invertible operators and frame-preserving operators. Furthermore, we show that weighted composition operator preserves frames if and only if it preserves the Riesz bases property. Additionally,we investigate the weighted composition operators that preserve tight or normalized tight frames on the Dirichlet space.

关键词： Weighted composition operators Weighted Hardy spaces frames invertible

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Creep constitutive model considering nonlinear creep degradation of fractured rock

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International Journal of Mining Science and Technology 2024年第1期34卷 105-116页

作者： Wang Chunping liu Jianfeng Chen Liang liu Jian Wang lu Liao Yilin Beijing Research Institute of Uranium Geology Beijing 100029China CAEA Innovation Center for Geological Disposal of High-Level Radioactive Waste Beijing 100029China State Key Laboratory of Hydraulics and Mountain River Engineering Sichuan UniversityChengdu 610065China School of Architecture and Civil Engineering Xihua UniversityChengdu 610039China

Stability analysis of underground constructions requires a model study of rock masses’ long-term performance. Creep tests under different stress conditions was conducted on intact granite and granite samples fractured at 30° and 45° angles. The experimental results indicate that the steady creep strain rates of intact and fractured rock present an exponential increase trend with the increase of stress level. A nonlinear creep model is developed based on the experimental results, in which the initial damage caused by fracture together with the damage caused by constant load have been taken into consideration. The fitting analysis results indicated that the model proposed is more accurate at identifying the full creep regions in fractured granite, especially the accelerated stage of creep deformation. The least-square fit error of the proposed creep model is significantly lower than that of Nishihara model by almost an order of magnitude. An analysis of the effects of elastic modulus, viscosity coefficient, and damage factors on fractured rock strain rate and creep strain is conducted. If no consideration is given to the effects of the damage, the proposed nonlinear creep model can degenerate into to the classical Nishihara model.

关键词： Fractured rock Damage Creep Beishan granite Geological disposal

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Procyanidin A_1 and its digestive products alleviate acrylamide-induced IPEC-J2 cell damage through regulating Keap1/Nrf2 pathway

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Food Science and Human Wellness 2024年第3期13卷 1475-1484页

作者： Fangfang Yan Qun lu Chengming Wang Rui liu College of Food Science and Technology Huazhong Agricultural UniversityWuhan 430070China Key Laboratory of Environment Correlative Dietology(Huazhong Agricultural University) Ministry of EducationWuhan 430070China Key Laboratory of Urban Agriculture in Central China Ministry of Agriculture and Rural AffairsWuhan 430070China

Our previous study has revealed that procyanidin A_(1)(A_(1))and its simulated digestive product(D-A,)can alleviate acrylamide(ACR)-induced intestine cell ***,the underlying mechanism remains *** this study,we elucidated the molecular mechanism for and D-A_(1) to alleviate ACR-stimulated IPEC-J2 cell *** slightly activated nuclear factor erythroid 2-related factor 2(Nrf2)signaling and its target genes,but this activation could not reduce intestine cell damage.A_(1) and D-A_(1) could alleviate ACR-induced cell damage,but the effect was abrogated in cells transiently transfected with Nrf2 small interfering RNA(siRNA).Further investigation confirmed that A_(1) and D-A_(1) interacted with Ketch-like ECH-associated protein 1(Keapl),which boosted the stabilization of Nrf2,subsequently promoted the translocation of Nrf2 into the nucleus,and further increased the expression of antioxidant proteins,thereby inhibiting glutathione(GSH)consumption,maintaining redox balance and eventually alleviating ACR-induced cell ***,there was no difference between A_(1) and D-A_(1) treated groups,indicating that A_(1) can tolerate gastrointestinal digestion and may be a potential compound to limit the toxicity of ACR.

关键词： Procyanidin A_1 Digestive products Acrylamide Nuclear factor erythroid 2-related factor 2(Nrf2) Intestinal cell damage

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Morphological and Sulfur-Isotopic Characteristics of Pyrites in the Deep Sediments from Xisha Trough,South China Sea

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Journal of Ocean University of China 2024年第1期23卷 138-148页

作者： CHANG Jingyi liu Yujia lu Hailong lu Jing’an SU Xin YE Jianliang XIE Wenwei College of Engineering Peking UniversityBeijing 100871China Beijing International Center for Gas Hydrate School of Earth and Planetary SciencesPeking UniversityBeijing 100871China School of Marine Science Nanjing University of Information Science and TechnologyNanjing 210044China MLR Key Laboratory of Marine Mineral Resources Guangzhou Marine Geological SurveyMinistry of Land and ResourcesGuangzhou 510075China School of Ocean Sciences China University of GeosciencesBeijing 100083China

Pyrite is one of the common authigenic minerals in marine *** studies have shown that the morphological and isotopic characteristics of pyrite are closely related to the geochemical environment where it is *** better understand the for-mation mechanism of authigenic pyrite,we analyzed the isotopic composition,morphology,and distribution of pyrite in the sediment at 500m below the seafloor from Xisha Trough,South China *** morphologies were observed by scanning electron micros-copy and Raman spectrography.X-Ray computed tomography was applied to measure the particle size of *** size of pyrite crystals in the matrix sediment mainly ranged between 25 and 65µm(***.40µm),although crystals were larger(***.50μm)in the *** pyrites had a fine-grained truncated octahedral shape with occasionally well-developed growth steps,which implies the low growth rate and weak anaerobic oxidation of methane-sulfate reduction when pyrite was ***δ^(34)S values of pyrites ranged from+20.8‰Vienna-defined Canyon Diablo Troilite(V-CDT)to+33.2‰V-CDT and from+44.8‰V-CDT to+48.9‰,which suggest two growth *** the first stage,with the continuous low methane flux,the pyrite possibly formed in an environment with good access to *** the second stage,the pyrites mainly developed in sediment fractures and appeared in veins,probably due to the limited availability of *** less exposure of pyrite to the environment in the second stage was probably caused by sediment accumulation or *** this study,an episodic pyritization process was identified,and the paleoenvironment was reconstructed for the sediment investigated.

关键词： pyrite sulfur isotope AOM methane flux Xisha Trough South China Sea

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Capacitor Voltage Imbalance Mechanism and Balancing Control of MMC When Riding Through PTG Fault

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CSEE Journal of Power and Energy Systems 2024年第2期10卷 778-785页

作者： Zhen He Maozeng lu Lijun Hang Pingliang Zeng Yanhua liu Hangzhou Dianzi University Hangzhou 310018China Shandong University of Technology Zibo 255000China State Grid Hangzhou Power Supply Company State GridHangzhou 310000China

Modular multilevel converter (MMC) based fault ride through (FRT) control is a promising solution to deal with the pole-to-ground (PTG) fault in high voltage direct current (HVDC) system. However, when MMC switches to the FRT control, capacitor voltage imbalance between upper and lower arms will occur, resulting in the deterioration of FRT performance. This letter provides a comprehensive analysis for the imbalance issue from the perspective of fundamental frequency circulating current (FFCC). It is found the imbalance during FRT stage will not expand continuously, but converge to a certain value gradually. The specific imbalance degree is closely associated with the amplitude of FFCC. In order to solve the imbalance issue, an open-loop balancing control is proposed. By introducing a fundamental frequency feedforward item to the inherent circulating current control, the proposed method can not only balance the capacitor voltages, but also minimize the amplitude of FFCC, and consequently the power loss of MMC during FRT process can be reduced. Finally, simulation results of PSCAD/ EMTDC verify the validity of theoretical analysis.

关键词： Balancing control capacitor voltage imbalance FFCC FRT control HVDC system PTG fault

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Multiple isotopes reveal the driving mechanism of high NO_(3)^(-) level and key processes of nitrogen cycling in the lower reaches of Yellow River

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Journal of Environmental Sciences 2024年第4期138卷 597-606页

作者： Qianqian Zhang Huiwei Wang lu liu Tianlun Zhai Xueqing Zhang Hebei and China Geological Survey Key Laboratory of Groundwater Remediation Institute of Hydrogeology and Environmental GeologyChinese Academy of Geological SciencesHebei 050061China Geo-Environmental Monitoring Institute of Hebei Province Hebei 050011China Hebei Provincial Laboratory of Water Environmental Science Hebei 050037China Hebei Provincial Academy of Ecological Environmental Science Hebei 050037China

The continuous increase of nitrate(NO_(3)^(-))level in rivers is a hot issue in the ***,the driving mechanism of high NO_(3)^(-)level in large rivers is still lacking,which has limited the use of river water and increased the cost of water *** this study,multiple isotopes and source resolution models are applied to identify the driving mechanism of high NO_(3)^(-)level and key processes of nitrogen cycling in the lower reaches of the Yellow River(LRYR).The major sources of NO_(3)^(-)were sewage and manure(SAM)in the low-flow season and soil nitrogen(SN)and chemical fertilizer(CF)in the high-flow *** was the most key process of nitrogen cycling in the ***,in the biological removal processes,denitrification may not occur *** temporal variation of contributions of NO_(3)^(-)sources were estimated by a source resolution model in the *** proportional contributions of SAM and CF to NO_(3)^(-)in the low-flow and high-flow season were 32.5%-52.3%,44.2%-46.2%and 36.0%-40.8%,54.9%-56.9%,*** driving mechanisms of high NO_(3)^(-)level were unreasonable sewage discharge,intensity rainfall runoff,nitrification and lack of nitrate removal *** control the NO_(3)^(-)concentration,targeted measures should be implemented to improve the capacity of sewage and wastewater treatment,increase the utilization efficiency of nitrogen fertilizer and construct ecological *** study deepens the understanding of the driving mechanism of high nitrate level and provides a vital reference for nitrogen pollution control in rivers to other area of the world.

关键词： Nitrate Driving mechanism Nitrogen cycle Source apportionment Transformation Yellow River

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