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49 results on '"Ma, Jiaji"'

1. Emergent topological states via digital (001) oxide superlattices

Author

Liu, Zhiwei, Liu, Hongquan, Ma, Jiaji, Wang, Xiaoxuan, Li, Gang, and Chen, Hanghui

Subjects
Condensed Matter - Materials Science
Abstract

Oxide heterostructures exhibit many intriguing properties. Here we provide design principles for inducing multiple topological states in (001) ($AM$O$_3$)$_1$/($AM'$O$_3$)$_1$ oxide superlattices. Aided by first-principles calculations and model analysis, we show that a (Sr$M$O3)$_1$/(Sr$M'$O$_3$)$_1$ superlattice ($M$ = Nb, Ta and $M'$ = Rh, Ir) is a strong topological insulator with $Z_2$ index (1;001). More remarkably, a (SrMoO3)$_1$/(SrIrO3)$_1$ superlattice exhibits multiple coexisting topological insulator (TI) and topological Dirac semi-metal (TDS) states. The TDS state has a pair of type-II Dirac points near the Fermi level and symmetry-protected Dirac node lines. The surface TDS Dirac cone is sandwiched by two surface TI Dirac cones in the energy-momentum space. The non-trivial topological properties arise from the band inversion between $d$ orbitals of two dissimilar transition metal atoms and a particular parity property of (001) superlattice geometry. Our work demonstrates how to induce nontrivial topological states in (001) perovskite oxide heterostructures by rational design., Comment: 29 pages, 6 figures and 1 table

Published
2022
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3. A large modulation of electron-phonon coupling and an emergent superconducting dome in doped strong ferroelectrics

Author

Ma, Jiaji, Yang, Ruihan, and Chen, Hanghui

Subjects
Condensed Matter - Materials Science, Condensed Matter - Superconductivity
Abstract

We use first-principles methods to study doped strong ferroelectrics (taking BaTiO$_3$ as a prototype). Here we find a strong coupling between itinerant electrons and soft polar phonons in doped BaTiO$_3$, contrary to Anderson/Blount's weakly coupled electron mechanism for "ferroelectric-like metals". As a consequence, across a polar-to-centrosymmetric phase transition in doped BaTiO$_3$, the total electron-phonon coupling is increased to about 0.6 around the critical concentration, which is sufficient to induce phonon-mediated superconductivity of about 2 K. Lowering the crystal symmetry of doped BaTiO$_3$ by imposing epitaxial strain can further increase the superconducting temperature via a sizable coupling between itinerant electrons and acoustic phonons. Our work demonstrates a viable approach to modulating electron-phonon coupling and inducing phonon-mediated superconductivity in doped strong ferroelectrics and potentially in polar metals. Our results also show that the weakly coupled electron mechanism for "ferroelectric-like metals" is not necessarily present in doped strong ferroelectrics., Comment: 24 pages, 4 figures

Published
2021
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5. Correlation-driven eightfold magnetic anisotropy in a two-dimensional oxide monolayer

Author

Cui, Zhangzhang, Grutter, Alexander J., Zhou, Hua, Cao, Hui, Dong, Yongqi, Gilbert, Dustin A., Wang, Jingyuan, Liu, Yi-Sheng, Ma, Jiaji, Hu, Zhenpeng, Guo, Jinghua, Xia, Jing, Kirby, Brian J., Shafer, Padraic, Arenholz, Elke, Chen, Hanghui, Zhai, Xiaofang, and Lu, Yalin

Subjects
Condensed Matter - Materials Science
Abstract

Engineering magnetic anisotropy in two-dimensional systems has enormous scientific and technological implications. The uniaxial anisotropy universally exhibited by two-dimensional magnets has only two stable spin directions, demanding 180 degrees spin switching between states. We demonstrate a novel eightfold anisotropy in magnetic SrRuO3 monolayers by inducing a spin reorientation in (SrRuO3)1/(SrTiO3)N superlattices, in which the magnetic easy axis of Ru spins is transformed from uniaxial <001> direction (N = 1 and 2) to eightfold <111> directions (N = 3, 4 and 5). This eightfold anisotropy enables 71 and 109 degrees spin switching in SrRuO3 monolayers, analogous to 71 and 109 degrees polarization switching in ferroelectric BiFeO3. First-principle calculations reveal that increasing the SrTiO3 layer thickness induces an emergent correlation-driven orbital ordering, tuning spin-orbit interactions and reorienting the SrRuO3 monolayer easy axis. Our work demonstrates that correlation effects can be exploited to substantially change spin-orbit interactions, stabilizing unprecedented properties in two-dimensional magnets and opening rich opportunities for low-power, multi-state device applications., Comment: 15+13 pages, 5+10 figures, including supplementary materials

Published
2020
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19. Aggregate size characterisation and porosity analysis of granular mixtures.

Author

Zhou, Yuhui, Liu, Yu, Ma, Jiaji, Yan, Chenyang, and Wang, Ruiyang

Subjects
PARTICLE size distribution, POROSITY, MIXTURES, RATIO & proportion, CONTOURS (Cartography)
Abstract

This paper aims to explore the correlate relationship between particle size composition and porosity of particles and reveal its influence mechanism. First, aggregate particles were divided into coarse aggregate, medium aggregate and fine aggregate. Combination of the particle size ratio and mixing proportion of each grade aggregate were used to characterize the particle size distribution. Second, a mixture proportion triangular coordinate system was proposed; and a series of void ratio contour maps of granular mixtures were plotted in the coordinates based on results of the discrete element numerical simulation test. Finally, correlation between mixture composition and porosity has been analysed. It was found that (1) The void ratio of mixtures with different particle size ratio combinations is mainly different from the size and distribution. (2) Both proportion and particle size composition of coarse aggregate are main factors affecting the change of porosity. (3) For mixtures with the maximum particle size of 16 mm, various particle size ratios within that definition of coarse aggregate are possible. Suitable combination schemes of particle size ratio for each grade of aggregate are recommended for the gradation evaluation and design. (4) The relationship between gradations and voids for the granular mixtures has been established and quantitatively characterised.. [ABSTRACT FROM AUTHOR]

Published
2023
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32. Electrically compensated, tattoo-like electrodes for epidermal electrophysiology at scale

Author

Wang, Youhua, primary, Yin, Lang, additional, Bai, Yunzhao, additional, Liu, Siyi, additional, Wang, Liu, additional, Zhou, Ying, additional, Hou, Chao, additional, Yang, Zhaoyu, additional, Wu, Hao, additional, Ma, Jiaji, additional, Shen, Yaoxin, additional, Deng, Pengfei, additional, Zhang, Shuchang, additional, Duan, Tangjian, additional, Li, Zehan, additional, Ren, Junhui, additional, Xiao, Lin, additional, Yin, Zhouping, additional, Lu, Nanshu, additional, and Huang, YongAn, additional

Published
2020
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33. Correlation-driven eightfold magnetic anisotropy in a two-dimensional oxide monolayer

Author

Cui, Zhangzhang, primary, Grutter, Alexander J., additional, Zhou, Hua, additional, Cao, Hui, additional, Dong, Yongqi, additional, Gilbert, Dustin A., additional, Wang, Jingyuan, additional, Liu, Yi-Sheng, additional, Ma, Jiaji, additional, Hu, Zhenpeng, additional, Guo, Jinghua, additional, Xia, Jing, additional, Kirby, Brian J., additional, Shafer, Padraic, additional, Arenholz, Elke, additional, Chen, Hanghui, additional, Zhai, Xiaofang, additional, and Lu, Yalin, additional

Published
2020
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40. Effects of Heat Treatment on Microstructure, Mechanical Properties, Corrosion Resistance and Cytotoxicity of ZM21 Magnesium Alloy as Biomaterials.

Author

Jiang, Dayue, Dai, Yilong, Zhang, Yu, Yan, Yang, Ma, Jiaji, Yu, Kun, and Li, Ding

Subjects
MAGNESIUM alloys, HEAT treatment of metals, BIOMATERIALS, METAL microstructure, MECHANICAL properties of metals, CORROSION resistance, CELL-mediated cytotoxicity
Abstract

The effects of heat treatment on microstructure, mechanical properties, corrosion resistance and cytotoxicity of extruded Mg-2Zn-1Mn (wt.%) alloy were investigated for biomedical application in this study. The extruded alloy was T4 treated at 510 °C for 4 h and T5 treated at 200 °C for 16 h separately. The extruded Mg-Zn-Mn alloy mainly consists of MgxMny phases. After T4 treatment, the amount of MgxMny phases decreases and average grain size rises from 8 to 24 μm. After T5 treatment, Mg7Zn3 phase newly precipitates along the grain boundaries and the size of grain remains similar. Compared with the T4-treated samples, the extruded and T5-treated samples exhibit higher mechanical properties. The T5-treated samples have an ultimate tensile stress of 273 MPa and an elongation of 19.7%. On the other hand, T4-treated samples present higher corrosion resistance in electrochemical tests. The degradation rates of extruded, T4-treated and T5-treated samples are 0.44 mm/year, 0.48 mm/year and 0.50 mm/year, respectively, in Ringer's solution at 37 ± 0.2 °C. In addition, T4-treated alloy does not induce toxicity to the L-929 cells in in vitro cytotoxicity test. [ABSTRACT FROM AUTHOR]

Published
2019
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41. Alloying of Zn-27% Al with antimony

Author

Ma Jiaji and Geng Haoran

Subjects
010302 applied physics, Materials science, Mechanical Engineering, Metallurgy, Alloy, Metals and Alloys, chemistry.chemical_element, 02 engineering and technology, engineering.material, 01 natural sciences, 020501 mining & metallurgy, 0205 materials engineering, Antimony, chemistry, Mechanics of Materials, 0103 physical sciences, engineering
Abstract

In the work reported in this paper, the authors investigated the effects of antimony in ZA 27 alloy (Zn-27wt% Al) on its mechanical properties, friction and wear behaviour, ageing, and “underside” ...

Published
1999

43. Friction and wear of AlZnPb bearing alloy

Author

Geng Haoran and Ma Jiaji

Subjects
6111 aluminium alloy, Materials science, Bearing (mechanical), Alloy, Metallurgy, Surfaces and Interfaces, engineering.material, 5005 aluminium alloy, Condensed Matter Physics, Microstructure, Indentation hardness, Surfaces, Coatings and Films, law.invention, Corrosion, Mechanics of Materials, law, Materials Chemistry, engineering, Bronze
Abstract

A new kind of Al Zn based alloy containing Pb has been designed. Its friction and wear behaviour was studied in comparison with that of SAE 660 bronze and ZA27 zinc alloy. The results showed that the addition of Pb is effective in improving the antifrictional property of aluminum alloys. The Al Zn Pb alloy is superior to SAE 660 bronze and ZA27 alloy in wear resistance and antifriction; its load bearing capacity is higher than that of SAE 660 bronze. Furthermore, Al Zn Pb alloy is superior to ZA27 alloy in corrosion resistance and dimensional stability. It is concluded that Al Zn Pb alloy has good bearing properties and could work under medium sliding speed at a higher load condition with lower cost; so using Al Zn Pb alloy to substitute for bronze to make some sliding bearing parts has economical significance. The microstructure and microhardness of Al Zn Pb and SAE 660 bronze have been examined in order to explain the mechanism of their friction and wear behaviour.

Published
1993

45. Nodularisation of Eutectic Silicon by Potassium in As-cast Al-Si Alloys

Author

Ma Jiaji and Hui Xidong

Subjects
010302 applied physics, Materials science, Silicon, Potassium, Metallurgy, chemistry.chemical_element, 02 engineering and technology, General Medicine, 01 natural sciences, 020303 mechanical engineering & transports, 0203 mechanical engineering, chemistry, Aluminium, 0103 physical sciences, Unidirectional solidification, Eutectic system
Abstract

An investigation has been carried out on the mechanism relating to the nodularisation of eutectic silicon by potassium in as-cast aluminium alloys, under conditions of unidirectional solidification...

Published
1992

49. [Advances of salt stress-responsive transcription factors in plants].

Author

Pan L, Ma J, Li J, Yin B, and Fu C

Subjects
Osmotic Pressure, Plant Proteins genetics, Plant Proteins metabolism, Plants, Genetically Modified, Salt Stress, Salt Tolerance, Stress, Physiological, Gene Expression Regulation, Plant, Transcription Factors genetics, Transcription Factors metabolism
Abstract

Salt stress may cause primary osmotic stress and ion toxicity, as well as secondary oxidative stress and nutritional stress in plants, which hampers the agricultural production. Salt stress-responsive transcription factors can mitigate the damage of salt stress to plants through regulating the expression of downstream target genes. Based on the soil salinization and its damage to plants, and the central regulatory role of transcription factors in the plant salt stress-responsive signal transduction network, this review summarized the salt stress-responsive signal transduction pathways that the transcription factors are involved, and the application of salt stress-responsive transcription factors to enhance the salt tolerance of plants. We also reviewed the transcription factors-regulated complex downstream gene network which is formed by forming homo- or heterodimers between transcription factors and by forming complexes with regulatory proteins. This paper provides a theoretical basis for understanding the role of salt stress-responsive transcription factors in the salt stress regulatory network, which may facilitate the molecular breeding for improved stress resistance.

Published
2022
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