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Your search keyword '"He, Zhiwen"' showing total 104 results
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104 results on '"He, Zhiwen"'

2. New constructions of signed difference sets

Author

He, Zhiwen, Chen, Tingting, and Ge, Gennian

Subjects
Mathematics - Combinatorics
Abstract

Signed difference sets have interesting applications in communications and coding theory. A $(v,k,\lambda)$-difference set in a finite group $G$ of order $v$ is a subset $D$ of $G$ with $k$ distinct elements such that the expressions $xy^{-1}$ for all distinct two elements $x,y\in D$, represent each non-identity element in $G$ exactly $\lambda$ times. A $(v,k,\lambda)$-signed difference set is a generalization of a $(v,k,\lambda)$-difference set $D$, which satisfies all properties of $D$, but has a sign for each element in $D$. We will show some new existence results for signed difference sets by using partial difference sets, product methods, and cyclotomic classes.

Published
2023

5. Plasmonic metafiber for all-fiber Q-switched cylindrical vector lasers

Author

Hua He, Zeng Chao, He Zhiwen, Lu Hua, Du Yueqing, Mao Dong, and Zhao Jianlin

Subjects
cylindrical vector beam, fiber laser, metafiber, metasurface, structured laser, Physics, QC1-999
Abstract

Metafibers, by integrating metasurface at the optical fiber tip, are emerging as the significant optical coupling platforms for nanophotonics and fiber-optic communities. Here, we propose a plasmonic metafiber for converting the fundamental mode to first-order mode in fiber, and as proof of device performance, demonstrate an all-fiber Q-switched cylindrical vector laser using the metafiber. Based on polarization-dependent plasmonic resonance, a polarization-independent mode conversion metasurface is designed theoretically and numerically, fabricated directly on fiber facet, and packaged as an all-fiber component with efficiency up to 21% at 1550-nm band. Using the metafiber in an all-fiber laser, Q-switched azimuthally polarized beam (APB) and radially polarized beam (RPB) are delivered at wavelength of 1548.5 nm with pulse durations from ∼7 to ∼2 μs when pump power increases from 30 to 120 mW. The mode purities of the APB and RPB are 86.5% and 90.7%, respectively. This work outlines a new strategy to integrate metasurfaces into “all-in-fiber” systems and offers a reliable route to construct next-generation laser sources, such as all-fiber ultrafast structured lasers.

Published
2023
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12. Tunable Electronic and Magnetic Properties of 3 d Transition Metal Atom-Intercalated Transition Metal Dichalcogenides: A Density Functional Theory Study.

Author

Liu, Yujie, Yang, Guang, He, Zhiwen, Wang, Yanbiao, Niu, Xianghong, Wang, Sake, Liu, Yongjun, and Zhang, Xiuyun

Subjects
TRANSITION metals, FERROMAGNETIC materials, DIFFUSION barriers, MAGNETIC structure, DENSITY functional theory
Abstract

Currently, intercalation has become an effective way to modify the fundamental properties of two-dimensional (2D) van der Waals (vdW) materials. Using density functional theory, we systematically investigated the structures and electronic and magnetic properties of bilayer transition metal dichalcogenides (TMDs) intercalated with 3d TM atoms (TM = Sc–Ni), TM@BL_MS2 (M = Mo, V). Our results demonstrate that all the studied TM@BL_MS2s are of high stability, with large binding energies and high diffusion barriers of TM atoms. Interestingly, most TM@BL_MoS2s and TM@BL_VS2s are found to be stable ferromagnets. Among them, TM@BL_MoS2s (TM = Sc, Ti, Fe, Co) are ferromagnetic metals, TM@BL_MoS2 (TM = V, Cr) and TM@BL_VS2 (TM = Sc, V) are ferromagnetic half-metals, and the remaining systems are found to be ferromagnetic semiconductors. Exceptions are found for Ni@BL_MoS2 and Cr@BL_VS2, which are nonmagnetic semiconductors and ferrimagnetic half-metals, respectively. Further investigations reveal that the electromagnetic properties of TM@BL_MoS2 are significantly influenced by the concentration of intercalated TM atoms. Our study demonstrates that TM atom intercalation is an effective approach for manipulating the electromagnetic properties of two-dimensional materials, facilitating their potential applications in spintronic devices. [ABSTRACT FROM AUTHOR]

Published
2024
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14. CaY@C2n: Exploring Molecular Qubits with Ca–Y Metal–Metal Bonds

Author

Qiu, Jiawei, Abella, Laura, Du, Xiya, Cao, Zhengkai, He, Zhiwen, Meng, Qingyu, Yan, Yingjing, Poblet, Josep M., Sun, Lei, Rodríguez-Fortea, Antonio, and Chen, Ning

Abstract

Metal–metal bonding is crucial in chemistry for advancing our understanding of the fundamental aspects of chemical bonds. Metal–metal bonds based on alkaline-earth (Ae) elements, especially the heavier Ae elements (Ca, Sr, and Ba), are rarely reported due to their high electropositivity. Herein, we report two heteronuclear di-EMFs CaY@Cs(6)-C82and CaY@C2v(5)-C80, which contain unprecedented single-electron Ca–Y metal–metal bonds. These compounds were characterized by single-crystal X-ray crystallography, electron paramagnetic resonance (EPR) spectroscopy, and DFT calculations. The crystallographic study of CaY@Cs(6)-C82shows that Ca and Y are successfully encapsulated into the carbon cage with a Ca–Y distance of 3.691 Å. The CW-EPR study of both CaY@Cs(6)-C82and CaY@C2v(5)-C80exhibits a doublet, suggesting the presence of an unpaired electron located between Ca and Y. The combined experimental and theoretical results confirm the presence of a Ca–Y single-electron metal–metal bond with substantial covalent interaction, attributed to significant overlap between the 4s4p orbitals of Ca and the 5s5p4d orbitals of Y. Furthermore, pulse EPR spectroscopy was used to investigate the quantum coherence of the electron spin within this bond. The unpaired electron, characterized by its s orbital nature, is effectively protected by the carbon cage, resulting in efficient suppression of both spin–lattice relaxation and decoherence. CaY@Cs(6)-C82behaves as an electron spin qubit, displaying a maximum decoherence time of 7.74 μs at 40 K. This study reveals an unprecedented Ae–rare-earth metal–metal bond stabilized by the fullerene cages and elucidates the molecular qubit properties stemming from their unique bonding character, highlighting their potential in quantum information processing applications.

Published
2024
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17. Acyl-coenzyme A: cholesterol acyltransferase inhibitor avasimibe suppresses tumorigenesis and induces G1-phase cell-cycle arrest by activating PPARγ signaling pathway in bladder cancer

Author

Peng, Tianchen, primary, Xiong, Kangping, additional, He, Zhiwen, additional, Cheng, Songtao, additional, Chen, Siming, additional, Chen, Song, additional, Yang, Zhonghua, additional, Xiang, Wan, additional, Ju, Lingao, additional, Zhang, Yi, additional, Qian, Kaiyu, additional, Xiao, Yu, additional, and Wang, Gang, additional

Published
2024
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30. Constant L₁-Weight Codes Under L∞-Metric

Author

Chen, Tingting, He, Zhiwen, and Ge, Gennian

Abstract

This paper studies the construction of constant $L_{1}$ -weight codes under $L_{\infty }$ -metric, which could be used to design codes addressing 0-indels (i.e., the insertion/deletion of 0’s only). Based on the patterns of small codes, we determine the maximum size for codes with distance 2 and length 3 for any constant weight, and several constructions and algorithms for suboptimal codes with general length $w+1$ are also provided. In general, for codes with distance D, length $w+1$ , and weight $tD+r$ , we derive the size of the largest code by using Hall’s theorem for integers $r=0$ , $t\in [{0,3}]$ and $w\geq t-1$ . When $r=\frac {D}{2}$ with D being even, codes with a cardinality that surpasses the known existing sizes by the additive term $\left \lceil{ \frac {1}{3}\binom {t+1}{2}}\right \rceil \left \lfloor{ \frac {w+1}{3}}\right \rfloor $ are constructed based on the structure of group divisible designs in combinatorics.

Published
2024
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38. Ultrasensitive tumour‐agnostic non‐invasive detection of colorectal cancer recurrence using ctDNA methylation

Author

Xiao, Yu, primary, Wang, Xiaodong, additional, Weng, Hong, additional, Ding, Zhao, additional, Qian, Kaiyu, additional, Jin, Wan, additional, Lu, Sen, additional, Ju, Lingao, additional, He, Zhiwen, additional, Wang, Gang, additional, Xie, Xiaoyu, additional, Liu, Dongmei, additional, Fan, Zhou, additional, Wu, Kai, additional, Li, Sheng, additional, Guo, Huanhuan, additional, Qian, Guofeng, additional, Jiang, Wei, additional, Leng, Yunji, additional, Zhao, Junpeng, additional, Cao, Xinyue, additional, Peng, Minsheng, additional, Jiang, Congqing, additional, Li, Li, additional, Zhang, Yi, additional, and Wang, Xinghuan, additional

Published
2022
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