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Small-Scale heterogeneity and Seismic Anisotropy in the Mid-Mantle:Oceanic Crust versus Meta-Stable Olivine

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Journal of Earth Science 2022年第4期33卷 1056-1058页

作者： xiaobo he Department of Ocean Exploration and Technology Zhejiang Ocean UniversityZhoushan 316022China

The mid-mantle(i.e.,the top lower mantle) roughly represents the mantle portion ranging from ~700 to 1 600 km *** has received increasing attention mainly due to two facts including(i) subducted slabs largely trapped there(Fukao and Obayashi,2013) and(ii) plume necking and lateral ponding at ~1 000 km depth(French and Romanowicz,2015).

关键词： mantle Seismic depths

Sharpness of the paired 660-km discontinuity beneath the Izu-Bonin area

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Earth and Planetary Physics 2020年第6期4卷 627-638页

作者： LiMing Wang xiaobo he Department of Marine Sciences Zhejiang UniversityZhoushan Zhejiang 316021China Marine Acoustics and Remote Sensing Laboratory Zhejiang Ocean UniversityZhoushan Zhejiang 316022China

The 660-km discontinuity that separates the Earth's upper and lower mantle has primarily been attributed to phase changes in olivine and other *** the sharpness is essential for predicting the composition of the mantle and for understanding its dynamic *** this study,we used S-to-P conversions from the 660-km interface,termed S660P,arriving in the P-wave coda from one earthquake in the Izu–Bonin subduction zone recorded by stations in *** S660P signals were of high quality,providing us an unprecedented opportunity to resolve the sharpness of the *** study demonstrated,based on the impedance contrast given by the IASP91 model,that the discontinuity has a transitional thickness of^5 *** addition,we observed a prominent arrival right after the S660P,which was best explained by S-to-P conversions from a deeper discontinuity at a depth of^720 km with a transitional thickness of^20 km,termed *** 720-km discontinuity is most likely the result of a phase transition from majoritic garnet to perovskite in the segregated oceanic crust(mainly the mid-oceanic ridge basalt composition)at the uppermost lower mantle beneath this *** inferred phase changes are also consistent with predictions from mineral physics experiments.

关键词： 660-km discontinuity S-to-P conversions Izu-Bonin sharpness mid-oceanic ridge basalt

Subducting passive continental margins with crustal (ultra)mafic intrusions: An underappreciated mechanism for recycling water back into the mantle

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Earth and Planetary Physics 2023年第5期7卷 576-581页

作者： CaiCai Pan xiaobo he Marine Science&Technology College Zhejiang Ocean UniversityZhoushan Zhejiang 316022China

It is well known that outer rise bending-assisted oceanic plate hydration is an important mechanism for transporting substantial amounts of water into the mantle.A key question is:Are there other equally or more important water transport mechanisms?here we propose,for the first time,that subducting passive continental margins,particularly those with crustal(ultra)mafic intrusions,play a critical role in recycling water back into the *** for this mechanism is the exceptionally high outer rise seismicity observed in a subducting passive continental margin(i.e.,the northeastern South China Sea continental margin)near the northern Manila trench,characterized by a high-velocity lower crust that has been attributed to(ultra)mafic *** interpretation of this correlation between high outer rise seismicity and lower crust(ultra)mafic intrusions is that(ultra)mafic intrusions alter the crustal rheology and increase brittle deformation in the lower crust in this region,thereby promoting lithospheric fracturing and plate hydration,which is evidenced by increased outer rise seismicity.

关键词： (ultra)mafic intrusion passive margin lithospheric fracturing outer rise plate hydration

Unintended Consequences of Lockdowns:Evidence from Domestic helpers in Urban China

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Frontiers of Economics in China-Selected Publications from Chinese Universities 2020年第4期15卷 521-540页

作者： xiaobo he Fang Xiao School of Business Shanghai University of International Business and EconomicsShanghai 201620China The Centre for Global Food and Resources The University of AdelaideAdelaideSouth Australia 5005Australia

This paper addresses the reactions of domestic helpers to the Wuhan(Hubei Province)lockdown that began on January 23,*** use a novel dataset containing the information of over 40,000 Chinese domestic helpers registered on a leading professional website from November 2019 to June *** results indicate a declining pattern of short-term labor supply of domestic helpers across 11 major Chinese cities,which shows an increase in the expected monthly wage of domestic helpers in these *** importantly,using a difference-in-difference(DID)model,this paper provides some evidence on the existence of labor market discrimination against domestic helpers bom in Hubei Province due to employers’fear of infection.

关键词： 2019 novel coronavims disease(COVID-19) pandemic domestic helpers urban China labor supply expected wage labor market discrimination

No seamount subduction,no magmatic arc?

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Earth and Planetary Physics 2022年第4期6卷 424-429页

作者： xiaobo he JunTao Tao Yi Cao FaBin Pan EnYuan he LingMin Cao YiXian Zheng Department of Ocean Exploration&Technology Zhejiang Ocean UniversityZhoushan Zhejiang 316022China School of Earth Sciences China University of GeosciencesWuhan 430074China Key Laboratory of Ocean and Marginal Sea Geology South China Sea Institute of OceanologyChinese Academy of SciencesGuangzhou 510301China Department of Marine Sciences Zhejiang UniversityZhoushan Zhejiang 316021China

Water is essential for the formation of a magmatic arc by lowering the melting temperature of materials in the mantle *** such,it is logical to attribute the absence of a magmatic arc to insufficient water released from the subducting plate,although a number of other factors may cause volcanic arc quiescence as well,such as a slab window or flat slab *** this contribution,we present a possible but testable correlation between the occurrence of a magmatic arc and seamount subduction in light of bathymetric data obtained near *** correlation,if it holds true,in turn means that a magmatic arc is unlikely to occur when the subducting slabs have not been severely fractured and that one of the main reasons for excluding effects such as the slab window or flat slab subduction may be that the plate is not accompanied by ***,the role that seamount subduction plays in recycling water back into the mantle deserves more attention from the earth sciences community.

关键词： seamount subduction arc volcano slab dehydration slab faulting bathymetric anomaly

Seismic evidence for the existence of an entrained mantle flow coupling the northward advancing Indian plate under Tibet

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Earth and Planetary Physics 2019年第1期3卷 62-68页

作者： Yu Zou xiaobo Tian YouQiang Yu Fa-Bin Pan LingLing Wang xiaobo he Department of Marine Sciences Zhejiang University State Key Laboratory of Lithospheric Evolution Institute of Geology and Geophysics Chinese Academy of Sciences School of Ocean and Earth Science Tongji University State Key Laboratory of Geological Process and Mineral Resources China University of Geosciences

The Tibetan Plateau, known as "the roof of the world" and "the third pole of the earth", is a product of the collision between India and Asia during the last ～50 *** regional tectonics–in particular, growth and expansion of the plateau–has been attributed primarily to deformation within the *** role and pattern of the underlying asthenospheric flow, however, remain mostly *** light of recent seismic tomographic images and published seismic anisotropic descriptions of the upper mantle, here we propose that an entrained mantle flow is likely to exist under Tibet, induced by the northward advancing Indian *** direction of mantle flow is characterized by a gradual rotation from northward in the south to eastward in the north as a result of deflection by the deep root of the Tarim *** presence of an underlying mantle flow is not only able to account for the west-east oriented fast-axis of seismic anisotropy in northern Tibet, but can also adequately explain the sporadic null splitting in southern ***, the null splitting results, at least in part, from upwellings of asthenospheric flow through tears of the underthrusting Indian plate that have been revealed by various seismic *** mantle flow may in turn promote the block extrusion under Tibet that has been observed in GPS measurements; hot asthenospheric upwellings may also lead to widespread post-collisional magmatism in southern Tibet.

关键词： Tibet seismic anisotropy mantle flow null splitting upwelling

High halogenated nitrobenzene hydrogenation selectivity over nano Ir particles

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Chinese Journal of Chemical Engineering 2017年第3期25卷 306-312页

作者： Lei Ma Jianguo Wang Hanbing Wang Qunfeng Zhang Chunshan Lu xiaobo he Xiaonian Li Industrial Catalysis Institute of Zhejiang University of Technology State Key Laboratory Breeding Base of Green Chemistry Synthesis TechnologyHangzhou 310032China

The selective hydrogenation of halogenated nitrobenzene over noble metal catalysts(Pd, Pt, and Ir) has attracted much attention owing to its high efficiency and environmental friendliness. However, the effect of size on the catalytic performance varies among different metal catalysts. In this study, sub-nano(heir catalytic properties for hydrogenation of halogenated nitrobenzene were *** show that high selectivity(N 99%) was achieved over small Ir nanoparticles, in which the selectivity over the Pd with same size was much lower than that on Ir nanoparticles. Meanwhile, Ir and Pd have different hydrogen consumption rates and reaction rates. Density functional theory calculations showed that p-chloronitrobenzene(CNB) has different adsorption properties on Ir and Pd. The distance between oxygen(cholorine) and Ir is much shorter(longer) than that between oxygen and Pd. The reaction barriers of dechlorination of p-CNB and p-chloroaniline over different Ir models are much larger than those on Pd. Especially,lower coordination of Ir leads to larger barriers of dechlorination reaction. These theoretical results explain the difference between Ir and Pd on hydrogenation of halogenated nitrobenzene.

关键词： Halogenated nitrobenzene Selective hydrogenation Sub-nano lr Density functional

Pressure-tuning domain-wall chirality in noncentrosymmetric magnetic Weyl semimetal CeAlGe

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Science China(Physics,Mechanics & Astronomy) 2023年第3期66卷 121-129页

作者： xiaobo he Yuke Li Hai Zeng Zengwei Zhu Shiyong Tan Yongjun Zhang Chao Cao Yongkang Luo Wuhan National High Magnetic Field Center and School of Physics Huazhong University of Science and TechnologyWuhan 430074China School of Physics and Hangzhou Key Laboratory of Quantum Matter Hangzhou Normal UniversityHangzhou 311121China Science and Technology on Surface Physics and Chemistry Laboratory Mianyang 621908China Institute for Advanced Materials Hubei Normal UniversityHuangshi 435002China Center for Correlated Matter and School of Physics Zhejiang UniversityHangzhou 310058China

Topological magnetic Weyl semimetals have been proposed to host controllable chiral domain walls which bear a great prospect in device applications. To exploit them in applications, it is important to have a proper way to tune and manipulate these domain walls. One possible means is through magnetoelastic coupling. The involvement of rare earth in the lately proposed RAl X(R =rare earth, X = Si and Ge) family magnetic Weyl semimetals may provide such a platform. here we present the transport and thermodynamic properties of Ce Al Ge under hydrostatic pressure. We find that pressure enhances the antiferromagnetic exchange in Ce Al Ge but essentially retains its magnetic structure. A large topological Hall effect with a pronounced loop shape is observed within the magnetically ordered state, and it splits into two regions under pressure. Such an unusual electromagnetic response is inferred to be a consequence of chiral magnetic domain walls. The unprecedented concomitance of its evolution under pressure and the reentrance of antiferromagnetic order strongly suggest the capability of switching on/off this electromagnetic response in noncentrosymmetric magnetic Weyl semimetals via magnetoelastic coupling.

关键词： magnetic Weyl semimetals loop-shaped topological Hall effect domain wall Weyl point magnetoelastic coupling

Carbonaceous matter in glacier at the headwaters of the Yangtze River:Concentration,sources and fractionation during the melting process

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Journal of Environmental Sciences 2020年第1期32卷 389-397页

作者： Zhaofu Hu Shichang Kang xiaobo he Fangping Yan Yulan Zhang Pengfei Chen Xiaofei Li Shaopeng Gao Chaoliu Li State Key Laboratory of Cryospheric Science Northwest Institute of Eco-environment and ResourcesChinese Academy of SciencesLanzhou 730000China Key Laboratory of Tibetan Environment Changes and Land Surface Processes Institute of Tibetan Plateau ResearchChinese Academy of SciencesBeijing 100085China Department of Green Chemistry School of Engineering ScienceLappeenranta-Lahti University of Technology LUTSammonkatu 12FI-50130 MikkeliFinland CAS Center for Excellence in Tibetan Plateau Earth Sciences Chinese Academy of SciencesBeijing 100101China University of Chinese Academy of Sciences Beijing 100049China Key Laboratory of Aerosol Chemistry and Physics Institute of Earth EnvironmentChinese Academy qf SciencesXi'an 710000China

Carbonaceous matter has an important impact on glacial retreat in the Tibetan Plateau,further affecting the water resource ***,the related studies on carbonaceous matter are still scarce in Geladaindong(GLDD)region,the source of the Yangtze ***,the concentration,source and variations of carbonaceous matter at Ganglongjiama(GLJM)glacier in GLDD region were investigated during the melting period in 2017,which could deepen our understanding on carbonaceous matter contribution to glacier *** results showed that dissolved organic carbon(DOC)concentration of snowpit samples(283±200μg/L)was much lower than that of precipitation samples(624±361μg/L),indicating that large parts of DOC could be rapidly leached from the snowpit during the melting *** contrast,refractory black carbon(rBC)concentration measured by Single Particle Soot Photometer of snowpit samples(4.27±3.15μg/L)was much higher than that of precipitation samples(0.97±0.49μg/L).Similarly,DOC with high mass absorption cross-section measured at 365 nm value was also likely to enrich in snowpit during the melting *** addition,it was found that both r BC and DOC with high light-absorbing ability began to leach from the snowpit when melting process became ***,rBC and DOC with high light-absorbing ability exhibited similar behavior during the melting *** on relationship among DOC,rBC and K^+ in precipitation,the main source of carbonaceous matter in GLJM glacier was biomass burning during the study period.

关键词： Carbonaceous matter Major ions Melting process Light absorption characteristic Tibetan Plateau