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2. Optically levitated gyroscopes with a MHz rotating micro-rotor

Author

Zeng, Kai, Xu, Xiangming, Wu, Yulie, Wu, Xuezhong, and Xiao, Dingbang

Subjects
Physics - Optics
Abstract

The optically levitated particles have been driven to rotate at an ultra-high speed of GHz, and the gyroscopic application of these levitated particles to measure angular motion have long been explored. However, this gyroscope has not been proven either theoretically or experimentally. Here, a rotor gyroscope based on optically levitated high-speed rotating particles is proposed. In vacuum, an ellipsoidal vaterite particle with 3.58 $\mu$m average diameter is driven to rotate at MHz, and the optical axis orientation of the particle is measured by the particle rotational signal. The external inputted angular velocity makes the optical axis deviate from the initial position, which changes the frequency and amplitude of the rotational signal. The inputted angular velocity is hence detected by the rotational signal, and the angular rate bias instability of the prototype is measured to be $0.08^o/s$. It is the smallest rotor gyroscope in the world, and the bias instability can be further improved up to $10^{-9o}/h$ theoretically by cooling the motion and increasing the angular moment of the levitated particle. Our work opens a new application paradigm of the levitated optomechanical systems and possibly bring the rotor gyroscope to the quantum realm.

Published
2023
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7. Transcription Factor VdCf2 Regulates Growth, Pathogenicity, and the Expression of a Putative Secondary Metabolism Gene Cluster in Verticillium dahliae

Author

Liu, Tao, Qin, Jun, Cao, Yonghong, Subbarao, Krishna V, Chen, Jieyin, Mandal, Mihir K, Xu, Xiangming, Shang, Wenjing, and Hu, Xiaoping

Subjects
Microbiology, Plant Biology, Biological Sciences, Bioinformatics and Computational Biology, Genetics, Biotechnology, 1.1 Normal biological development and functioning, Underpinning research, Virulence, Verticillium, Transcription Factors, Secondary Metabolism, Fungal Proteins, Melanins, Virulence Factors, Multigene Family, Host-Pathogen Interactions, Plant Diseases, Verticillium dahliae, transcription factor, VdCf2, pathogenicity, transcriptome, gene cluster, Medical microbiology
Abstract

Transcription factors (TFs) bind to the promoters of target genes to regulate gene expression in response to different stimuli. The functions and regulatory mechanisms of transcription factors (TFs) in Verticillium dahliae are, however, still largely unclear. This study showed that a C2H2-type zinc finger TF, VdCf2 (V. dahliae chorion transcription factor 2), plays key roles in V. dahliae growth, melanin production, and virulence. Transcriptome sequencing analysis showed that VdCf2 was involved in the regulation of expression of genes encoding secreted proteins, pathogen-host interaction (PHI) homologs, TFs, and G protein-coupled receptors (GPCRs). Furthermore, VdCf2 positively regulated the expression of VdPevD1 (VDAG_02735), a previously reported virulence factor. VdCf2 thus regulates the expression of several pathogenicity-related genes that also contribute to virulence in V. dahliae. VdCf2 also inhibited the transcription of the Vd276-280 gene cluster and interacted with two members encoding proteins (VDAG_07276 and VDAG_07278) in the gene cluster. IMPORTANCE Verticillium dahliae is an important soilborne phytopathogen which can ruinously attack numerous host plants and cause significant economic losses. Transcription factors (TFs) were reported to be involved in various biological processes, such as hyphal growth and virulence of pathogenic fungi. However, the functions and regulatory mechanisms of TFs in V. dahliae remain largely unclear. In this study, we identified a new transcription factor, VdCf2 (V. dahliae chorion transcription factor 2), based on previous transcriptome data, which participates in growth, melanin production, and virulence of V. dahliae. We provide evidence that VdCf2 regulates the expression of the pathogenicity-related gene VdPevD1 (VDAG_02735) and Vd276-280 gene cluster. VdCf2 also interacts with VDAG_07276 and VDAG_07278 in this gene cluster based on a yeast two-hybrid and bimolecular fluorescence complementation assay. These results revealed the regulatory mechanisms of a pivotal pathogenicity-related transcription factor, VdCf2 in V. dahliae.

Published
2022

8. Solution-processed van der Waals heterojunction as the damage-free gate contact for high performance GaN HEMTs

Author

Wang, Chuanju, Xu, Xiangming, Hedhili, Mohamed Nejib, Alshareef, Husam N., and Li, Xiaohang

Subjects
Physics - Chemical Physics
Abstract

The junctions formed between gate contact and III-nitride are crucial components of GaN-based electronics and optoelectronics. In this work, solution-processed inorganic Ti3C2Tx MXene films were spray coated on the AlGaN/GaN epitaxial wafer as the gate contact. The workfounction of MXene films was effectively enhanced by partial oxidization process, and accordingly, the gate leakage current and off-state drain current were significantly suppressed. The van der Waals heterojunction between MXene films and III-nitride without direct chemical bonding retained the pristine atomically flat native oxides of III-nitride, record high Ion/Ioff current ratio of 1013, and near ideal subthreshold swing of 61 mV/dec was achieved in the Schottky-Type gate GaN HEMTs. In addition, the MXene gate GaN HEMTs display superior electron mobility and transcoductance, high uniformity with 20 measured transistors. The unprecedented performance can be correlated to the damage-free interface between MXene and III-nitride, negligible atomic diffusion of MXene into the semiconductor layer, and excellent adhesion between MXene and III-nitride. This work provides an alternative method to create contact not only in GaN HEMTs but also in other electronic and optoelectronic devices which uniquely features cost-effective, non-vacuum, high deposition rate, and damage-free properties.

Published
2022

14. Lower serum uric acid and impairment of right cerebral hemisphere structural brain networks are related to depressive symptoms in cerebral small vessel disease: A cross-sectional study

Author

Yu, Lei, Yi, Ming, Guo, Jiayu, Li, Jinbiao, Zeng, Huixing, Cui, Liqian, Xu, Xiangming, Liu, Gang, Fan, Yuhua, Zeng, Jinsheng, Xing, Shihui, Chen, Yicong, Wang, Meng, Tan, Shuangquan, Jin, Leow Yi, Kumar, Dilip, Vipin, Ashwati, Ann, Soo See, Binte Zailan, Fatin Zahra, Sandhu, Gurveen Kaur, Kandiah, Nagaendran, and Dang, Chao

Published
2024
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15. Integrated silicon optomechanical system and its applications

Author

Xu, Xiangming and Yan, Jize

Abstract

Optomechanics studies the interaction between the optical force and mechanical objects, and has led to intensive developments in ultra-sensitive measurements, coherent quantum control, optical tweezers, etc. Silicon photonics is a material platform from which Photonics Integrated Circuits can be made, and provide a perfect solution for minimising optical systems. This thesis studies the integration of optomechanics and silicon photonics-integrated silicon optomechanics, and explores its applications in distributed fibre optical sensing (DFOS) and optical trapping. A novel 1.5 µm thick Silicon on Insulator (SOI) platform is also demonstrated, which is advantageous to the two applications compared to the widely-used thin SOI platform. Firstly, this thesis proposes to use the integrated cavity optomechanical system to generate optical probe signals for DFOS. The proposed application is based on optomechanical oscillation (OMO), through which optical pulse trains (OPT) and sweepingwavelength optical signals (SWOS) for the DFOS application can be generated. Comprehensive analyses on the OMO threshold and oscillation characteristics are conducted, and the extinction ratio (ER), duty cycle (DC) of the OPT and the sweeping range of the SWOS are derived. Examples of utilising OMO-based OPT and SWOS for DFOS applications are then demonstrated. The proposed OMO-based OPT generator and OMO-Based SWOS generator do not rely on external RF sources and optical modulators and can be fully integrated with silicon photonics platform. They thus provide unconventional methods to reshape the optical source generation in DFOS. Secondly, this thesis presents the design, optimisation and scaling effect of a dualwaveguide optical trap on a SOI platform by comprehensive numerical simulations in Lumerical FDTD Solutions. The simulations demonstrate that the waveguide thickness is a crucial parameter in designing a dual waveguide optical trap. It was found the optimal waveguide thickness generally increases with the gap distance, accompanied by a periodic feature. The optimal waveguide thickness and gap distance display clear scaling effects over the optical wavelength. This thesis also proposes to use the OMO process to load micro/nano-particles. The OMO process can break the adhesive connection between the micro/nano-particles and the container's surface. The works above not only pave the way for the design and optimisation of dual-waveguide optical trappings for various applications, but also lays the foundation of a fully on-chip optical trapping system working on vacuum or air. Lastly, this thesis experimentally demonstrated a novel 1.5 µm thick SOI platform for integrated optomechanics, rather than the widely-used thin SOI with a top silicon layer less than 300 nm. For both the above two applications, thick SOI shows its advantages. Thick SOI is suitable for fabricating low-frequency mechanical resonators, which are necessary for long-distance DFOS applications. Thick SOI is also essential for dualwaveguide optical trapping with a larger gap distance. In addition, the 1.5 µm thick SOI has high power handling capability, low propagation loss, large mode size, and comparatively small bend radius. Individual integrated silicon optomechanical components based on 1.5 µm SOI platform are designed, fabricated, and measured, including waveguides, grating couplers, MMIs, Bragg gratings, optical microresonators and mechanical resonators. The measurement results show that all the individual photonics components function well. These works lay a solid foundation for the full integration of a silicon optomechanical system in the future.

Published
2021

19. Genomic analysis, trajectory tracking, and field surveys reveal sources and long-distance dispersal routes of wheat stripe rust pathogen in China

Author

Li, Yuxiang, Dai, Jichen, Zhang, Taixue, Wang, Baotong, Zhang, Siyue, Wang, Conghao, Zhang, Jiguang, Yao, Qiang, Li, Mingju, Li, Chengyun, Peng, Yuelin, Cao, Shiqin, Zhan, Gangming, Tao, Fei, Gao, Haifeng, Huang, Weili, Feng, Xiaojun, Bai, Yingwen, Qucuo, Zhuoma, Shang, Hongsheng, Huang, Chong, Liu, Wancai, Zhan, Jiasui, Xu, Xiangming, Chen, Xianming, Kang, Zhensheng, and Hu, Xiaoping

Published
2023
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25. Fusarium pseudograminearum biomass and toxin accumulation in wheat tissues with and without Fusarium crown rot symptoms

Author

Xu, Fei, primary, Shi, Ruijie, additional, Liu, Lulu, additional, Li, Shufang, additional, Wang, Junmei, additional, Han, Zihang, additional, Liu, Wei, additional, Wang, Hongqi, additional, Liu, Jihong, additional, Fan, Jieru, additional, Wang, Aolin, additional, Feng, Chaohong, additional, Song, Yuli, additional, Zhou, Yilin, additional, and Xu, Xiangming, additional

Published
2024
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32. Synchronously Enhancing Mechanical Strength and Conductivity of MXene Nanofluidic Fibers with Multivalent Ion Crosslinking

Author

Li, Shuo, primary, Yang, Zhicheng, additional, Hu, Huimin, additional, Wang, Junchang, additional, Yang, Dongzi, additional, Wang, Yizhou, additional, Zhang, Liang, additional, Tong, Xiaoling, additional, Xia, Zhou, additional, Chen, Zhihui, additional, Lian, Xueyu, additional, Shi, Zixiong, additional, Xu, Xiangming, additional, Guo, Yinben, additional, Alshareef, Husam N., additional, and Shao, Yuanlong, additional

Published
2024
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35. Amplicon sequencing identified a putative pathogen, Macrophomina phaseolina, causing wilt in African eggplant (Solanum aethiopicum) grown in Tanzania and Uganda

Author

Xu, Xiangming, primary, Minja, Ruth, additional, Kizito, Elizabeth Balyejusa, additional, Dinssa, Fekadu, additional, Deakin, Greg, additional, Kabod, Pamela Nahamya, additional, Kalala, Asheri, additional, Kweka, Eliciana, additional, Mbwambo, Omary, additional, Mbanzibwa, Deusdedith, additional, Msangi, Hamza, additional, Nakanwagi, Mildred Julian, additional, Passey, Tom, additional, Sentance, Stuart, additional, Sseremba, Godfrey, additional, Stavridou, Eleftheria, additional, and Bishop, Gerard J., additional

Published
2024
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48. Anisotropic Superconducting Nb2CTx MXene Processed by Atomic Exchange at the Wafer Scale

Author

Xu, Xiangming, primary, Zhang, Chenghui, additional, Yin, Jun, additional, Smajic, Jasmin, additional, Bahabri, Mohammed, additional, Lei, Yongjiu, additional, Hedhili, Mohamed Nejib, additional, Hota, Mrinal K., additional, Shi, Lin, additional, Guo, Tianchao, additional, Zheng, Dongxing, additional, El‐Demellawi, Jehad K., additional, Lanza, Mario, additional, Costa, Pedro M. F. J., additional, Bakr, Osman M., additional, Mohammed, Omar F., additional, Zhang, Xixiang, additional, and Alshareef, Husam N., additional

Published
2023
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