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Article ; Online: Design and stability analysis of the gear-type mobile mechanism with a single actuator.

Shi, Kan / Tang, Jianglong / Liu, Jiachao / Yuan, Liang

2024 Volume 14, Issue 1, Page(s) 1922

Abstract: Gear mechanism transmits the motion and power of parallel axes, intersecting axes and staggered axes, which has been widely employed in production and life. Gear-type mobile mechanism is a type of robot that can achieve motion through gear transmission. ... ...

Abstract	Gear mechanism transmits the motion and power of parallel axes, intersecting axes and staggered axes, which has been widely employed in production and life. Gear-type mobile mechanism is a type of robot that can achieve motion through gear transmission. Due to its unique motion mode, it can handle various tasks in certain unconventional environments, such as particularly steep surfaces. Cylindrical gear, bevel gear and non-cylindrical gear are taken as the main parts of the mechanism to form a novel research series, respectively. The models of gear-type mobile mechanism are established in this paper, and the degrees of freedom of the mechanism are briefly calculated based on the screw theory. Simultaneously, the influence of centroid trajectory on motion stability is discussed to solve the possible problem that opposite rotation occur during the movement. Furthermore, the trajectory model of zero moment point is calculated considering the motion of the gear-type mobile mechanism. After that, the simulation and experimental analysis of its motion capability show that the gear-type mobile mechanism has excellent characteristics in stability, flexibility and continuity.
Language	English
Publishing date	2024-01-22
Publishing country	England
Document type	Journal Article
ZDB-ID	2615211-3
ISSN	2045-2322 ; 2045-2322
ISSN (online)	2045-2322
ISSN	2045-2322
DOI	10.1038/s41598-024-51248-8
Database	MEDical Literature Analysis and Retrieval System OnLINE

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Article ; Online: Metallic iron limits silicate hydration in Earth's transition zone.

Zhu, Feng / Li, Jie / Liu, Jiachao / Dong, Junjie / Liu, Zhenxian

Proceedings of the National Academy of Sciences of the United States of America

2019 Volume 116, Issue 45, Page(s) 22526–22530

Abstract: The Earth's mantle transition zone (MTZ) is often considered an internal reservoir for water because its major minerals wadsleyite and ringwoodite can store several oceans of structural water. Whether it is a hydrous layer or an empty reservoir is still ... ...

Abstract	The Earth's mantle transition zone (MTZ) is often considered an internal reservoir for water because its major minerals wadsleyite and ringwoodite can store several oceans of structural water. Whether it is a hydrous layer or an empty reservoir is still under debate. Previous studies suggested the MTZ may be saturated with iron metal. Here we show that metallic iron reacts with hydrous wadsleyite under the pressure and temperature conditions of the MTZ to form iron hydride or molecular hydrogen and silicate with less than tens of parts per million (ppm) water, implying that water enrichment is incompatible with iron saturation in the MTZ. With the current estimate of water flux to the MTZ, the iron metal preserved from early Earth could transform a significant fraction of subducted water into reduced hydrogen species, thus limiting the hydration of silicates in the bulk MTZ. Meanwhile, the MTZ would become gradually oxidized and metal depleted. As a result, water-rich region can still exist near modern active slabs where iron metal was consumed by reaction with subducted water. Heterogeneous water distribution resolves the apparent contradiction between the extreme water enrichment indicated by the occurrence of hydrous ringwoodite and ice VII in superdeep diamonds and the relatively low water content in bulk MTZ silicates inferred from electrical conductivity studies.
Language	English
Publishing date	2019-10-21
Publishing country	United States
Document type	Journal Article ; Research Support, U.S. Gov't, Non-P.H.S.
ZDB-ID	209104-5
ISSN	1091-6490 ; 0027-8424
ISSN (online)	1091-6490
ISSN	0027-8424
DOI	10.1073/pnas.1908716116
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Article: Spin Transitions and Compressibility of ε‐Fe7N3 and γ′‐Fe4N: Implications for Iron Alloys in Terrestrial Planet Cores

Lv, Mingda / Liu, Jiachao / Zhu, Feng / Li, Jie / Zhang, Dongzhou / Xiao, Yuming / Dorfman, Susannah M.

Journal of geophysical research. 2020 Nov., v. 125, no. 11

2020

Abstract: Iron nitrides are possible constituents of the cores of Earth and other terrestrial planets. Pressure‐induced magnetic changes in iron nitrides and effects on compressibility remain poorly understood. Here we report synchrotron X‐ray emission ... ...

Abstract	Iron nitrides are possible constituents of the cores of Earth and other terrestrial planets. Pressure‐induced magnetic changes in iron nitrides and effects on compressibility remain poorly understood. Here we report synchrotron X‐ray emission spectroscopy (XES) and X‐ray diffraction (XRD) results for ε‐Fe₇N₃ and γ′‐Fe₄N up to 60 GPa at 300 K. The XES spectra reveal completion of high‐ to low‐spin transition in ε‐Fe₇N₃ and γ′‐Fe₄N at 43 and 34 GPa, respectively. The completion of the spin transition induces stiffening in bulk modulus of ε‐Fe₇N₃ by 22% at ~40 GPa, but has no resolvable effect on the compression behavior of γ′‐Fe₄N. Fitting pressure‐volume data to the Birch‐Murnaghan equation of state yields V₀ = 83.29 ± 0.03 (Å³), K₀ = 232 ± 9 GPa, K₀′ = 4.1 ± 0.5 for nonmagnetic ε‐Fe₇N₃ above the spin transition completion pressure, and V₀ = 54.82 ± 0.02 (Å³), K₀ = 152 ± 2 GPa, K₀′ = 4.0 ± 0.1 for γ′‐Fe₄N over the studied pressure range. By reexamining evidence for spin transition and effects on compressibility of other candidate components of terrestrial planet cores, Fe₃S, Fe₃P, Fe₇C₃, and Fe₃C based on previous XES and XRD measurements, we located the completion of high‐ to low‐spin transition at ~67, 38, 50, and 30 GPa at 300 K, respectively. The completion of spin transitions of Fe₃S, Fe₃P, and Fe₃C induces elastic stiffening, whereas that of Fe₇C₃ induces elastic softening. Changes in compressibility at completion of spin transitions in iron‐light element alloys may influence the properties of Earth's and planetary cores.
Keywords	X-radiation ; X-ray diffraction ; compressibility ; equations ; geophysics ; magnetism ; research ; spectroscopy
Language	English
Dates of publication	2020-11
Publishing place	John Wiley & Sons, Ltd
Document type	Article
Note	JOURNAL ARTICLE
ISSN	2169-9313
DOI	10.1029/2020JB020660
Database	NAL-Catalogue (AGRICOLA)

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Article ; Online: Formation of large low shear velocity provinces through the decomposition of oxidized mantle.

Wang, Wenzhong / Liu, Jiachao / Zhu, Feng / Li, Mingming / Dorfman, Susannah M / Li, Jie / Wu, Zhongqing

Nature communications

2021 Volume 12, Issue 1, Page(s) 1911

Abstract: Large Low Shear Velocity Provinces (LLSVPs) in the lowermost mantle are key to understanding the chemical composition and thermal structure of the deep Earth, but their origins have long been debated. Bridgmanite, the most abundant lower-mantle mineral, ... ...

Abstract	Large Low Shear Velocity Provinces (LLSVPs) in the lowermost mantle are key to understanding the chemical composition and thermal structure of the deep Earth, but their origins have long been debated. Bridgmanite, the most abundant lower-mantle mineral, can incorporate extensive amounts of iron (Fe) with effects on various geophysical properties. Here our high-pressure experiments and ab initio calculations reveal that a ferric-iron-rich bridgmanite coexists with an Fe-poor bridgmanite in the 90 mol% MgSiO
Language	English
Publishing date	2021-03-26
Publishing country	England
Document type	Journal Article
ZDB-ID	2553671-0
ISSN	2041-1723 ; 2041-1723
ISSN (online)	2041-1723
ISSN	2041-1723
DOI	10.1038/s41467-021-22185-1
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Article: Synthesis, Elasticity, and Spin State of an Intermediate MgSiO3‐FeAlO3 Bridgmanite: Implications for Iron in Earth's Lower Mantle

Zhu, Feng / Liu, Jiachao / Lai, Xiaojing / Xiao, Yuming / Prakapenka, Vitali / Bi, Wenli / Alp, E. Ercan / Dera, Przemyslaw / Chen, Bin / Li, Jie

Journal of geophysical research. 2020 July, v. 125, no. 7

2020

Abstract: Fe‐Al‐bearing bridgmanite may be the dominant host for ferric iron in Earth's lower mantle. Here we report the synthesis of (Mg₀.₅Fe³⁺₀.₅)(Al₀.₅Si₀.₅)O₃ bridgmanite (FA50) with the highest Fe³⁺‐Al³⁺ coupled substitution known to date. X‐ray diffraction ... ...

Abstract	Fe‐Al‐bearing bridgmanite may be the dominant host for ferric iron in Earth's lower mantle. Here we report the synthesis of (Mg₀.₅Fe³⁺₀.₅)(Al₀.₅Si₀.₅)O₃ bridgmanite (FA50) with the highest Fe³⁺‐Al³⁺ coupled substitution known to date. X‐ray diffraction measurements showed that at ambient conditions, the FA50 adopted the LiNbO₃ structure. Upon compression at room temperature to 18 GPa, it transformed back into the bridgmanite structure, which remained stable up to 102 GPa and 2,600 K. Fitting Birch‐Murnaghan equation of state of FA50 bridgmanite yields V₀ = 172.1(4) Å³, K₀ = 229(4) GPa with K₀′ = 4(fixed). The calculated bulk sound velocity of the FA50 bridgmanite is ~7.7% lower than MgSiO₃ bridgmanite, mainly because the presence of ferric iron increases the unit‐cell mass by 15.5%. This difference likely represents the upper limit of sound velocity anomaly introduced by Fe³⁺‐Al³⁺ substitution. X‐ray emission and synchrotron Mössbauer spectroscopy measurements showed that after laser annealing, ~6% of Fe³⁺ cations exchanged with Al³⁺ and underwent the high‐ to low‐spin transition at 59 GPa. The low‐spin proportion of Fe³⁺ increased gradually with pressure and reached 17–31% at 80 GPa. Since the cation exchange and spin transition in this Fe³⁺‐Al³⁺‐enriched bridgmanite do not cause resolvable unit‐cell volume reduction, and the increase of low‐spin Fe³⁺ fraction with pressure occurs gradually, the spin transition would not produce a distinct seismic signature in the lower mantle. However, it may influence iron partitioning and isotopic fractionation, thus introducing chemical heterogeneity in the lower mantle.
Keywords	X-radiation ; X-ray diffraction ; ambient temperature ; cation exchange ; equations ; geophysics ; iron ; isotope fractionation ; research ; spectroscopy
Language	English
Dates of publication	2020-07
Publishing place	John Wiley & Sons, Ltd
Document type	Article
Note	JOURNAL ARTICLE
ISSN	2169-9313
DOI	10.1029/2020JB019964
Database	NAL-Catalogue (AGRICOLA)

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Article ; Online: Origins of ultralow velocity zones through slab-derived metallic melt.

Liu, Jiachao / Li, Jie / Hrubiak, Rostislav / Smith, Jesse S

Proceedings of the National Academy of Sciences of the United States of America

2016 Volume 113, Issue 20, Page(s) 5547–5551

Abstract: Understanding the ultralow velocity zones (ULVZs) places constraints on the chemical composition and thermal structure of deep Earth and provides critical information on the dynamics of large-scale mantle convection, but their origin has remained ... ...

Abstract	Understanding the ultralow velocity zones (ULVZs) places constraints on the chemical composition and thermal structure of deep Earth and provides critical information on the dynamics of large-scale mantle convection, but their origin has remained enigmatic for decades. Recent studies suggest that metallic iron and carbon are produced in subducted slabs when they sink beyond a depth of 250 km. Here we show that the eutectic melting curve of the iron-carbon system crosses the current geotherm near Earth's core-mantle boundary, suggesting that dense metallic melt may form in the lowermost mantle. If concentrated into isolated patches, such melt could produce the seismically observed density and velocity features of ULVZs. Depending on the wetting behavior of the metallic melt, the resultant ULVZs may be short-lived domains that are replenished or regenerated through subduction, or long-lasting regions containing both metallic and silicate melts. Slab-derived metallic melt may produce another type of ULVZ that escapes core sequestration by reacting with the mantle to form iron-rich postbridgmanite or ferropericlase. The hypotheses connect peculiar features near Earth's core-mantle boundary to subduction of the oceanic lithosphere through the deep carbon cycle.
Language	English
Publishing date	2016-05-17
Publishing country	United States
Document type	Journal Article ; Research Support, U.S. Gov't, Non-P.H.S. ; Research Support, Non-U.S. Gov't
ZDB-ID	209104-5
ISSN	1091-6490 ; 0027-8424
ISSN (online)	1091-6490
ISSN	0027-8424
DOI	10.1073/pnas.1519540113
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Article ; Online: Valence and spin states of iron are invisible in Earth's lower mantle.

Liu, Jiachao / Dorfman, Susannah M / Zhu, Feng / Li, Jie / Wang, Yonggang / Zhang, Dongzhou / Xiao, Yuming / Bi, Wenli / Alp, E Ercan

Nature communications

2018 Volume 9, Issue 1, Page(s) 1284

Abstract: Heterogeneity in Earth's mantle is a record of chemical and dynamic processes over Earth's history. The geophysical signatures of heterogeneity can only be interpreted with quantitative constraints on effects of major elements such as iron on physical ... ...

Abstract	Heterogeneity in Earth's mantle is a record of chemical and dynamic processes over Earth's history. The geophysical signatures of heterogeneity can only be interpreted with quantitative constraints on effects of major elements such as iron on physical properties including density, compressibility, and electrical conductivity. However, deconvolution of the effects of multiple valence and spin states of iron in bridgmanite (Bdg), the most abundant mineral in the lower mantle, has been challenging. Here we show through a study of a ferric-iron-only (Mg
Language	English
Publishing date	2018-03-29
Publishing country	England
Document type	Journal Article ; Research Support, Non-U.S. Gov't
ISSN	2041-1723
ISSN (online)	2041-1723
DOI	10.1038/s41467-018-03671-5
Database	MEDical Literature Analysis and Retrieval System OnLINE

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Article: Correlation between high density lipoprotein and monocyte subpopulations among stable coronary atherosclerotic heart disease patients.

Yang, Rong-Hai / Liu, Ying-Feng / Wang, Xue-Jun / Liang, Jian-Guang / Liu, Jia-Chao

publication RETRACTED

International journal of clinical and experimental medicine

2015 Volume 8, Issue 9, Page(s) 16969–16977

Abstract: High density lipoprotein (HDL) is a structurally and functionally heterogeneous molecular particle whose function is unclear in atherosclerosis at present. Studies show that small HDL functional imbalance may exist in Coronary Atherosclerotic Heart ... ...

Abstract	High density lipoprotein (HDL) is a structurally and functionally heterogeneous molecular particle whose function is unclear in atherosclerosis at present. Studies show that small HDL functional imbalance may exist in Coronary Atherosclerotic Heart Disease (CAD) patients. Monocyte is considered to play an important role in atherosclerosis, in accordance with the expression of superficial CD14 and CD16, it can be divided into three subpopulations. The purpose of this study was to explore the relation between HDL and monocyte subpopulations among CAD patients. We report 90 cases of stable CAD patients and define the monocyte subpopulations as classical monocyte (CD14++CD16-; CM), intermediate monocyte (CD14+CD16+; IM), and non-classical monocyte (CD14+CD16++; NCM); HDL group is measured by polyacrylamide gel electrophoresis. The results indicated that the small HDL in blood serum has a correlation with proinflammatory NCM in circulation but a negative correction with CM and no relationship with diabetes, saccharify hemoglobin, hypertension, smoking history and taking dose of statins drugs and severity of disease. In conclusion, this study primarily confirms that micromolecule HDL level correlates with the increase of non-classical monocyte subpopulations and decrease of classical monocyte quantity. Thus demonstrates the proinflammatory correlation between micromolecule HDL and internal immunity in the development of stable atherosclerosis.
Language	English
Publishing date	2015-09-15
Publishing country	United States
Document type	Journal Article ; Retracted Publication
ZDB-ID	2418305-2
ISSN	1940-5901
ISSN	1940-5901
Database	MEDical Literature Analysis and Retrieval System OnLINE

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Article ; Online: Hidden carbon in Earth's inner core revealed by shear softening in dense Fe7C3.

Chen, Bin / Li, Zeyu / Zhang, Dongzhou / Liu, Jiachao / Hu, Michael Y / Zhao, Jiyong / Bi, Wenli / Alp, E Ercan / Xiao, Yuming / Chow, Paul / Li, Jie

Proceedings of the National Academy of Sciences of the United States of America

2014 Volume 111, Issue 50, Page(s) 17755–17758

Abstract: Earth's inner core is known to consist of crystalline iron alloyed with a small amount of nickel and lighter elements, but the shear wave (S wave) travels through the inner core at about half the speed expected for most iron-rich alloys under relevant ... ...

Abstract	Earth's inner core is known to consist of crystalline iron alloyed with a small amount of nickel and lighter elements, but the shear wave (S wave) travels through the inner core at about half the speed expected for most iron-rich alloys under relevant pressures. The anomalously low S-wave velocity (vS) has been attributed to the presence of liquid, hence questioning the solidity of the inner core. Here we report new experimental data up to core pressures on iron carbide Fe7C3, a candidate component of the inner core, showing that its sound velocities dropped significantly near the end of a pressure-induced spin-pairing transition, which took place gradually between 10 GPa and 53 GPa. Following the transition, the sound velocities increased with density at an exceptionally low rate. Extrapolating the data to the inner core pressure and accounting for the temperature effect, we found that low-spin Fe7C3 can reproduce the observed vS of the inner core, thus eliminating the need to invoke partial melting or a postulated large temperature effect. The model of a carbon-rich inner core may be consistent with existing constraints on the Earth's carbon budget and would imply that as much as two thirds of the planet's carbon is hidden in its center sphere.
Language	English
Publishing date	2014-12-16
Publishing country	United States
Document type	Journal Article ; Research Support, Non-U.S. Gov't ; Research Support, U.S. Gov't, Non-P.H.S.
ZDB-ID	209104-5
ISSN	1091-6490 ; 0027-8424
ISSN (online)	1091-6490
ISSN	0027-8424
DOI	10.1073/pnas.1411154111
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