76 results on '"Zehan Wu"'
Search Results
2. Mixture Differential Cryptanalysis on Round-Reduced SIMON32/64 Using Machine Learning
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Zehan Wu, Kexin Qiao, Zhaoyang Wang, Junjie Cheng, and Liehuang Zhu
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SIMON ,ResNet ,mixture differential ,cryptanalysis ,Mathematics ,QA1-939 - Abstract
With the development of artificial intelligence (AI), deep learning is widely used in various industries. At CRYPTO 2019, researchers used deep learning to analyze the block cipher for the first time and constructed a differential neural network distinguisher to meet a certain accuracy. In this paper, a mixture differential neural network distinguisher using ResNet is proposed to further improve the accuracy by exploring the mixture differential properties. Experiments are conducted on SIMON32/64, and the accuracy of the 8-round mixture differential neural network distinguisher is improved from 74.7% to 92.3%, compared with that of the previous differential neural network distinguisher. The prediction accuracy of the differential neural network distinguisher is susceptible to the choice of the specified input differentials, whereas the mixture differential neural network distinguisher is less affected by the input difference and has greater robustness. Furthermore, by combining the probabilistic expansion of rounds and the neutral bit, the obtained mixture differential neural network distinguisher is extended to 11 rounds, which can realize the 12-round actual key recovery attack on SIMON32/64. With an appropriate increase in the time complexity and data complexity, the key recovery accuracy of the mixture differential neural network distinguisher can be improved to 55% as compared to 52% of the differential neural network distinguisher. The mixture differential neural network distinguisher proposed in this paper can also be applied to other lightweight block ciphers.
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- 2024
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3. Interface Engineering and Device Applications of 2D Ultrathin Film/Ferroelectric Copolymer P(VDF‐TrFE)
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Zhaoying Dang, Feng Guo, Zehan Wu, Kui Jin, and Jianhua Hao
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2D materials ,ferroelectrics ,field‐effect transistors ,interface physics ,P(VDF‐TrFE) ,Physics ,QC1-999 - Abstract
Abstract Ferroelectric materials with switchable electrical polarization have been widely used in tunnel junctions, non‐volatile memories, and field‐effect transistors. Large‐area organic ferroelectric polymers compatible with silicon or flexible substrates have played a crucial role in nanoelectronics. Poly(vinylidene fluoride‐trifluoroethylene) P(VDF‐TrFE) as a representative, different from traditional bulk oxide ferroelectrics in terms of atom arrangements and fabrication methods, has frequently been used as the ferroelectric gate for high‐performance electronic, optical, and synaptic transistors. Ferroelectric copolymers have gradually become a promising and versatile alternative for inorganic ferroelectrics. This review will focus on the interface engineering and device applications of 2D materials/ferroelectric P(VDF‐TrFE) hybrid structures. The intrinsic ferroelectric properties and unique features of P(VDF‐TrFE) are first elucidated. Next, typical device structures with ferroelectric gating effect followed by its physical working mechanisms will be discussed. In the next section, diverse nanoelectronics applications of ferroelectric field effect transistors based on P(VDF‐TrFE), including optoelectronic devices, non‐volatile memories, neuromorphic computing, and negative capacitance transistors, are clarified. Moreover, existing challenges and further development for ferroelectric polymer will be discussed. With an emphasis on the ferroelectric polymer gate and related issues, this review provides a timely summary of current physical understanding and progresses.
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- 2023
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4. Neural excitatory rebound induced by valproic acid may predict its inadequate control of seizures
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Xiang Zou, Zilu Zhu, Yu Guo, Hongmiao Zhang, Yuchen Liu, Zhengyu Cui, Zunji Ke, Shize Jiang, Yusheng Tong, Zehan Wu, Ying Mao, Liang Chen, and Deheng Wang
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Neural excitation ,Rebound ,Antiseizures medications ,Seizure ,Medicine ,Medicine (General) ,R5-920 - Abstract
Summary: Background: Valproic acid (VPA) represents one of the most efficient antiseizure medications (ASMs) for both general and focal seizures, but some patients may have inadequate control by VPA monotherapy. In this study, we aimed to verify the hypothesis that excitatory dynamic rebound induced by inhibitory power may contribute to the ineffectiveness of VPA therapy and become a predictor of post-operative inadequate control of seizures. Methods: Awake craniotomy surgeries were performed in 16 patients with intro-operative high-density electrocorticogram (ECoG) recording. The relationship between seizure control and the excitatory rebound was further determined by diagnostic test and univariate analysis. Thereafter, kanic acid (KA)-induced epileptic mouse model was used to confirm that its behavior and neural activity would be controlled by VPA. Finally, a computational simulation model was established to verify the hypothesis. Findings: Inadequate control of seizures by VPA monotherapy and post-operative status epilepticus are closely related to a significant excitatory rebound after VPA injection (rebound electrodes≧5/64, p = 0.008), together with increased synchronization of the local field potential (LFP). In addition, the neural activity in the model mice showed a significant rebound on spike firing (53/77 units, 68.83%). The LFP increased the power spectral density in multiple wavebands after VPA injection in animal experiments (p
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- 2022
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5. Assessing differential representation of hand movements in multiple domains using stereo-electroencephalographic recordings
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Guangye Li, Shize Jiang, Jianjun Meng, Guohong Chai, Zehan Wu, Zhen Fan, Jie Hu, Xinjun Sheng, Dingguo Zhang, Liang Chen, and Xiangyang Zhu
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Stereo-electroencephalography ,SEEG ,Movement decoding ,Brain-computer interface ,Neural representation ,Neurosciences. Biological psychiatry. Neuropsychiatry ,RC321-571 - Abstract
Invasive brain-computer interfaces (BCI) have made great progress in the reconstruction of fine hand movement parameters for paralyzed patients, where superficial measurement modalities including electrocorticography (ECoG) and micro-array recordings are mostly used. However, these recording techniques typically focus on the signals from the sensorimotor cortex, leaving subcortical regions and other cortical regions related to the movements largely unexplored. As an intracranial recording technique for the presurgical assessments of brain surgery, stereo-encephalography (SEEG) inserts depth electrodes containing multiple contacts into the brain and thus provides the unique opportunity for investigating movement-related neural representation throughout the brain. Although SEEG samples neural signals with high spatial-temporal resolutions, its potential of being used to build BCIs has just been realized recently, and the decoding of SEEG activity related to hand movements has not been comprehensively investigated yet. Here, we systematically evaluated the factors influencing the performance of movement decoding using SEEG signals recorded from 32 human subjects performing a visually-cued hand movement task. Our results suggest that multiple regions in both lateral and depth directions present significant neural selectivity to the task, whereas the sensorimotor area, including both precentral and postcentral cortex, carries the richest discriminative neural information for the decoding. The posterior parietal and prefrontal cortex contribute gradually less, but still rich sources for extracting movement parameters. The insula, temporal and occipital cortex also contains useful task-related information for decoding. Under the cortex layer, white matter presents decodable neural patterns but yields a lower accuracy (42.0 ± 0.8%) than the cortex on average (44.2 ± 0.8%, p
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- 2022
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6. Changes in lifestyle, mood, and disease management among community-dwelling older adults during the COVID-19 pandemic in China
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Saineng Ding, Qiqi Lei, Wanqing Wu, Zhenxu Xiao, Zehan Wu, Ming Chen, and Liang Chen
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COVID-19 ,Older adults ,Mood ,Chronic disease management ,Lifestyle ,Geriatrics ,RC952-954.6 - Abstract
Background: Lives of older adults have been greatly affected by the COVID-19 pandemic.Methods: A telephone survey was conducted among the older adults aged 60 and above who lived in downtown Shanghai. We compared the lifestyle, mood, and disease management of older adults before and during the COVID-19 pandemic.Results: One hundred and fifty-six older adults in Shanghai completed the survey. The proportions of older adults with adequate consumption of meat (49.4% vs. 53.1%, P = 0.0339) and eggs (73.7% vs. 77.6%, P = 0.0143) were significantly higher than before. Participants spent significantly more time on housework (median: 2.0, IQR:1.0–3.0 vs. median: 2.0, IQR:1.0–2.0 h/day; P = 0.0361) and leisure activities (median: 7.0, IQR: 5.0–8.6 vs. median: 6.0, IQR: 4.0–8.5 h/day; P
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- 2022
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7. Spontaneous State Detection Using Time-Frequency and Time-Domain Features Extracted From Stereo-Electroencephalography Traces
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Huanpeng Ye, Zhen Fan, Guangye Li, Zehan Wu, Jie Hu, Xinjun Sheng, Liang Chen, and Xiangyang Zhu
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stereo-electroencephalography ,brain-computer interface ,feature evaluation ,time-domain feature ,high-gamma ,Neurosciences. Biological psychiatry. Neuropsychiatry ,RC321-571 - Abstract
As a minimally invasive recording technique, stereo-electroencephalography (SEEG) measures intracranial signals directly by inserting depth electrodes shafts into the human brain, and thus can capture neural activities in both cortical layers and subcortical structures. Despite gradually increasing SEEG-based brain-computer interface (BCI) studies, the features utilized were usually confined to the amplitude of the event-related potential (ERP) or band power, and the decoding capabilities of other time-frequency and time-domain features have not been demonstrated for SEEG recordings yet. In this study, we aimed to verify the validity of time-domain and time-frequency features of SEEG, where classification performances served as evaluating indicators. To do this, using SEEG signals under intermittent auditory stimuli, we extracted features including the average amplitude, root mean square, slope of linear regression, and line-length from the ERP trace and three traces of band power activities (high-gamma, beta, and alpha). These features were used to detect the active state (including activations to two types of names) against the idle state. Results suggested that valid time-domain and time-frequency features distributed across multiple regions, including the temporal lobe, parietal lobe, and deeper structures such as the insula. Among all feature types, the average amplitude, root mean square, and line-length extracted from high-gamma (60–140 Hz) power and the line-length extracted from ERP were the most informative. Using a hidden Markov model (HMM), we could precisely detect the onset and the end of the active state with a sensitivity of 95.7 ± 1.3% and a precision of 91.7 ± 1.6%. The valid features derived from high-gamma power and ERP in this work provided new insights into the feature selection procedure for further SEEG-based BCI applications.
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- 2022
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8. Effects of Gaze Fixation on the Performance of a Motor Imagery-Based Brain-Computer Interface
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Jianjun Meng, Zehan Wu, Songwei Li, and Xiangyang Zhu
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brain-computer interface (BCI) ,electroencephalography (EEG) ,motor imagery ,gaze fixation ,covert attention ,Neurosciences. Biological psychiatry. Neuropsychiatry ,RC321-571 - Abstract
Motor imagery-based brain-computer interfaces (BCIs) have been studied without controlling subjects’ gaze fixation position previously. The effect of gaze fixation and covert attention on the behavioral performance of BCI is still unknown. This study designed a gaze fixation controlled experiment. Subjects were required to conduct a secondary task of gaze fixation when performing the primary task of motor imagination. Subjects’ performance was analyzed according to the relationship between motor imagery target and the gaze fixation position, resulting in three BCI control conditions, i.e., congruent, incongruent, and center cross trials. A group of fourteen subjects was recruited. The average group performances of three different conditions did not show statistically significant differences in terms of BCI control accuracy, feedback duration, and trajectory length. Further analysis of gaze shift response time revealed a significantly shorter response time for congruent trials compared to incongruent trials. Meanwhile, the parietal occipital cortex also showed active neural activities for congruent and incongruent trials, and this was revealed by a contrast analysis of R-square values and lateralization index. However, the lateralization index computed from the parietal and occipital areas was not correlated with the BCI behavioral performance. Subjects’ BCI behavioral performance was not affected by the position of gaze fixation and covert attention. This indicated that motor imagery-based BCI could be used freely in robotic arm control without sacrificing performance.
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- 2022
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9. Printing High‐Efficiency Perovskite Solar Cells in High‐Humidity Ambient Environment—An In Situ Guided Investigation
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Patrick Wai‐Keung Fong, Hanlin Hu, Zhiwei Ren, Kuan Liu, Li Cui, Tao Bi, Qiong Liang, Zehan Wu, Jianhua Hao, and Gang Li
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air‐knife assisted drying ,blade coating ,crystallization ,nucleation ,perovskite solar cells ,scalable ambient fabrication ,Science - Abstract
Abstract Extensive studies are conducted on perovskite solar cells (PSCs) with significant performance advances (mainly spin coating techniques), which have encouraged recent efforts on scalable coating techniques for the manufacture of PSCs. However, devices fabricated by blade coating techniques are inferior to state‐of‐the‐art spin‐coated devices because the power conversion efficiency (PCE) is highly dependent on the morphology and crystallization kinetics in the controlled environment and the delicate solvent system engineering. In this study, based on the widely studied perovskite solution system dimethylformamide–dimethyl sulfoxide, air‐knife‐assisted ambient fabrication of PSCs at a high relative humidity of 55 ± 5% is reported. In‐depth time‐resolved UV–vis spectrometry is carried out to investigate the impact of solvent removal and crystallization rate, which are critical factors influencing the crystallization kinetics and morphology because of adventitious moisture. UV–vis spectrometry enables accurate determination of the thickness of the wet precursor film. Anti‐solvent‐free, high‐humidity ambient coatings of hysteresis‐free PSCs with PCEs of 21.1% and 18.0% are demonstrated for 0.06 and 1 cm2 devices, respectively. These PSCs exhibit comparable stability to those fabricated in a glovebox, thus demonstrating their high potential.
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- 2021
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10. Electrocorticographic Temporal Alteration Mapping: A Clinical Technique for Mapping the Motor Cortex with Movement-Related Cortical Potentials
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Zehan Wu, Tao Xie, Lin Yao, Dingguo Zhang, Xinjun Sheng, Dario Farina, Liang Chen, Ying Mao, and Xiangyang Zhu
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intraoperative ,electrocorticography (ECoG) ,motor cortex mapping ,movement-related cortical potentials (MRCP) ,Neurosciences. Biological psychiatry. Neuropsychiatry ,RC321-571 - Abstract
We propose electrocorticographic temporal alteration mapping (ETAM) for motor cortex mapping by utilizing movement-related cortical potentials (MRCPs) within the low-frequency band [0.05-3] Hz. This MRCP waveform-based temporal domain approach was compared with the state-of-the-art electrocorticographic frequency alteration mapping (EFAM), which is based on frequency spectrum dynamics. Five patients (two epilepsy cases and three tumor cases) were enrolled in the study. Each patient underwent intraoperative direct electrocortical stimulation (DECS) procedure for motor cortex localization. Moreover, the patients were required to perform simple brisk wrist extension task during awake craniotomy surgery. Cross-validation results showed that the proposed ETAM method had high sensitivity (81.8%) and specificity (94.3%) in identifying sites which exhibited positive DECS motor responses. Moreover, although the sensitivity of the ETAM and EFAM approaches was not significantly different, ETAM had greater specificity compared with EFAM (94.3 vs. 86.1%). These results indicate that for the intraoperative functional brain mapping, ETAM is a promising novel approach for motor cortex localization with the potential to reduce the need for cortical electrical stimulation.
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- 2017
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11. Bitwise Mixture Differential Cryptanalysis and Its Application to SIMON.
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Kexin Qiao, Zehan Wu, Junjie Cheng, Changhai Ou, An Wang 0001, and Liehuang Zhu
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- 2024
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12. A Closer Look at the Belief Propagation Algorithm in Side-Channel-Assisted Chosen-Ciphertext Attacks.
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Kexin Qiao, Siwei Sun, Zhaoyang Wang, Zehan Wu, Junjie Cheng, An Wang 0001, and Liehuang Zhu
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- 2024
13. Phase-Amplitude Coupling between Neuronal Wideband Low-Frequency Oscillations and Broadband Gamma Activity.
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Tao Xie, Zehan Wu, Liang Chen 0023, Xiangyang Zhu, Xinjun Sheng, and Peter Brunner
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- 2021
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14. SEEGview: A Toolbox for Localization and Visualization of Stereo-Electroencephalography (SEEG) Electrodes.
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Guangye Li, Shize Jiang, Meng Wang, Zehan Wu, Peter Brunner, Gerwin Schalk, Liang Chen 0023, and Dingguo Zhang
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- 2018
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15. A preliminary study towards prosthetic hand control using human stereo-electroencephalography (SEEG) signals.
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Guangye Li, Shize Jiang, Yang Xu, Zehan Wu, Liang Chen 0023, and Dingguo Zhang
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- 2017
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16. Optimal referencing for stereo-electroencephalographic (SEEG) recordings.
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Guangye Li, Shize Jiang, Sivylla E. Paraskevopoulou, Meng Wang, Yang Xu, Zehan Wu, Liang Chen 0023, Dingguo Zhang, and Gerwin Schalk
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- 2018
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17. Progress in Piezo‐Phototronic Effect on 2D Nanomaterial‐Based Heterostructure Photodetectors
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Yuqian Zhao, Ran Ding, Feng Guo, Zehan Wu, and Jianhua Hao
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- 2022
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18. Synthesis and enhanced piezoelectric response of CVD-grown SnSe layered nanosheets for flexible nanogenerators
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Fumei Yang, Man-Chung Wong, Jianfeng Mao, Zehan Wu, and Jianhua Hao
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General Materials Science ,Electrical and Electronic Engineering ,Condensed Matter Physics ,Atomic and Molecular Physics, and Optics - Published
- 2022
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19. Strain-Induced Performance Enhancement of a Monolayer Photodetector via Patterned Substrate Engineering
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Jianfeng Mao, Zehan Wu, Feng Guo, and Jianhua Hao
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General Materials Science - Abstract
Two-dimensional (2D) materials exhibit tremendous potential for applications in next-generation photodetectors. Currently, approaches aiming at enhancing the device's performance are limited, mainly relying on complex hybrid systems such as heterostructures and sensitization. Here, we propose a new strategy by constructing patterned nanostructures compatible with the conventional silicon substrate. Using CVD-grown monolayer MoS
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- 2022
20. Large-scale growth of few-layer two-dimensional black phosphorus
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Zehan Wu, Shu Ping Lau, Yi Zhang, Xianhui Chen, Beining Zheng, Yongxin Lyu, Ran Ding, Zhibin Yang, and Jianhua Hao
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Electron mobility ,Materials science ,Silicon ,Band gap ,chemistry.chemical_element ,02 engineering and technology ,010402 general chemistry ,01 natural sciences ,law.invention ,Pulsed laser deposition ,law ,General Materials Science ,Laser ablation ,business.industry ,Mechanical Engineering ,Transistor ,Transistor array ,General Chemistry ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,0104 chemical sciences ,Semiconductor ,chemistry ,Mechanics of Materials ,Optoelectronics ,0210 nano-technology ,business - Abstract
Two-dimensional materials provide opportunities for developing semiconductor applications at atomistic thickness to break the limits of silicon technology. Black phosphorus (BP), as a layered semiconductor with controllable bandgap and high carrier mobility, is one of the most promising candidates for transistor devices at atomistic thickness1–4. However, the lack of large-scale growth greatly hinders its development in devices. Here, we report the growth of ultrathin BP on the centimetre scale through pulsed laser deposition. The unique plasma-activated region induced by laser ablation provides highly desirable conditions for BP cluster formation and transportation5,6, facilitating growth. Furthermore, we fabricated large-scale field-effect transistor arrays on BP films, yielding appealing hole mobility of up to 213 and 617 cm2 V−1 s−1 at 295 and 250 K, respectively. Our results pave the way for further developing BP-based wafer-scale devices with potential applications in the information industry. Centimetre-scale growth of few-layer black phosphorous with high crystalline quality and homogeneity is realized by pulsed laser deposition.
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- 2021
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21. Controllable Heterogenous Seeding-Induced Crystallization for High-Efficiency FAPbI
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Hengkai, Zhang, Zhiwei, Ren, Kuan, Liu, Minchao, Qin, Zehan, Wu, Dong, Shen, Yaokang, Zhang, Hrisheekesh Thachoth, Chandran, Jianhua, Hao, Chun-Sing, Lee, Xinhui, Lu, Zijian, Zheng, Jinsong, Huang, and Gang, Li
- Abstract
The addition of small seeding particles into a supersaturated solution is one among the most effective approaches to obtain high-quality semiconductor materials via increased crystallization rates. However, limited study is conducted on this approach for the fabrication of perovskite solar cells. Here, a new strategy-"heterogenous seeding-induced crystallization (hetero-SiC)" to assist the growth of FAPbI
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- 2022
22. Author response for 'Automated intraoperative central sulcus localization and somatotopic mapping using median nerve stimulation'
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null Tao Xie, null Zehan Wu, null Gerwin Schalk, null Yusheng Tong, null Alessandro Vato, null Nataly Raviv, null Qinglong Guo, null Huanpeng Ye, null Xinjun Sheng, null Xiangyang Zhu, null Peter Brunner, and null Liang Chen
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- 2022
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23. Zwitterionic-Surfactant-Assisted Room-Temperature Coating of Efficient Perovskite Solar Cells
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Xinhui Lu, Qiong Liang, Jiaming Huang, Zijian Zheng, Patrick W. K. Fong, Zehan Wu, Dong Shen, Gang Li, Kuan Liu, Yaokang Zhang, Jianhua Hao, Chun-Sing Lee, Hengkai Zhang, Minchao Qin, Hang Yin, Zhiwei Ren, and Shu Kong So
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Materials science ,Passivation ,Kinetics ,02 engineering and technology ,engineering.material ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,0104 chemical sciences ,law.invention ,Crystallization kinetics ,General Energy ,Chemical engineering ,Coating ,Pulmonary surfactant ,law ,Moisture barrier ,engineering ,Crystallization ,0210 nano-technology ,Perovskite (structure) - Abstract
Summary With amazing progress in the state-of-the-art perovskite solar cells (PSCs) fabricated by laboratory-scale spin-coating methods, upscaling the PSCs via printing friendly techniques is becoming more and more important toward the future deployment of large-scale and stable perovskite modules. Here, we demonstrate the room-temperature meniscus coating of high-quality perovskite films incorporated with a multifunctional sulfobetaine-based zwitterionic surfactant. Systematic in situ studies uncover the perovskite crystallization pathway and emphasize the surfactant’s synergistic role in film construction, crystallization kinetics modulation, defect passivation, and moisture barrier protection. This strategy is applicable across perovskite compositions and device architectures with the enhanced power conversion efficiencies up to 22%. Upscaling the device area to 0.8 cm2 has negligible deterioration in the performance. This represents one of the highest records for the upscaling coated PSCs, not limited in room-temperature coated PSCs. In addition, this approach significantly improves the stability of perovskite films and devices under different aging conditions.
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- 2020
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24. Efficient Flexible Perovskite Solar Cells Using Low-Cost Cu Top and Bottom Electrodes
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Gang Li, Zehan Wu, Jianhua Hao, Yaokang Zhang, Zhongwei Wu, Hong Hu, Zhiwei Ren, Hao-Li Zhang, Peng Li, Xi Lu, Zijian Zheng, and Ting Xiao
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Electrode material ,Materials science ,Opacity ,business.industry ,Photovoltaic system ,Halide ,02 engineering and technology ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,Flexible electronics ,0104 chemical sciences ,Electrode ,Optoelectronics ,General Materials Science ,0210 nano-technology ,business ,Electrical conductor - Abstract
Perovskite solar cells (PSCs) are promising technology for flexible photovoltaic applications because of the low cost and good flexibility of the halide perovskite materials. Nevertheless, the use of transparent conductive oxides (TCOs) and noble metals (e.g., Au and Ag) as PSC electrodes is very costly, and TCOs are too brittle for flexible applications. How to fabricate flexible PSCs (FPSCs) with cost-effective and soft electrode materials remains to be a big challenge. Herein, we report the first study of FPSCs using low-cost Cu electrodes. Both the transparent bottom electrode and the opaque top electrode are fabricated with Cu. FPSCs made with such Cu electrodes acquire a champion efficiency of 13.58% (Jsc of 17.79 mA cm-2, Voc of 1.031 V, and FF of 74.07%), which retains over 90% after 1000 cycles of bending at a small radius of curvature of 5 mm. The device shows negligible changes in Voc and FF after storage for 10 weeks without encapsulation.
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- 2020
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25. A General Wet Transferring Approach for Diffusion-Facilitated Space-Confined Grown Perovskite Single-Crystalline Optoelectronic Thin Films
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Sin Yi Pang, Weng Fu Io, Chun Ki Liu, Jianhua Hao, Michal Bartlomiej Jedrzejczyk, Jiong Zhao, Zehan Wu, Shuoguo Yuan, Feng Yan, Ran Ding, Lok Wing Wong, Feng Guo, and Man-Chung Wong
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Fabrication ,Materials science ,business.industry ,Mechanical Engineering ,Photodetector ,Bioengineering ,02 engineering and technology ,General Chemistry ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,Optoelectronics ,General Materials Science ,Nanometre ,Diffusion (business) ,Thin film ,0210 nano-technology ,business ,Perovskite (structure) - Abstract
Hybrid perovskite single-crystalline thin films are promising for making high-performance perovskite optoelectronic devices due to their superior physical properties. However, it is still challenging to incorporate them into multilayer devices because of their on-substrate growth. Here, a wet transfer method is used in transferring perovskite single-crystalline films perfectly onto various target substrates. More importantly, large millimeter-scaled single-crystalline films can be obtained via a diffusion-facilitated space-confined growth method as thin as a few hundred nanometers, which are capable of sustaining excellent crystalline quality and morphology after the transferring process. The availability of these crystalline films offers us a convenient route to further investigate their intrinsic properties of hybrid perovskites. We also demonstrate that the wet transfer method can be used for scalable fabrication of perovskite single-crystalline film-based photodetectors exhibiting a remarkable photoresponsivity. It is expected that this transferring strategy would promise broad applications of perovskite single-crystalline films for more complex perovskite devices.
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- 2020
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26. Electrical transport properties in group-V elemental ultrathin 2D layers
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Jianhua Hao and Zehan Wu
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Materials science ,Field (physics) ,02 engineering and technology ,010402 general chemistry ,01 natural sciences ,lcsh:Chemistry ,lcsh:TA401-492 ,General Materials Science ,Electronics ,Electronic band structure ,Anisotropy ,Spintronics ,business.industry ,Mechanical Engineering ,General Chemistry ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,Engineering physics ,Ferroelectricity ,0104 chemical sciences ,Magnetic field ,Semiconductor ,lcsh:QD1-999 ,Mechanics of Materials ,lcsh:Materials of engineering and construction. Mechanics of materials ,0210 nano-technology ,business - Abstract
After the breakthrough of the study on the two-dimensional (2D) layered phosphorus, group-V elemental ultrathin 2D layers have captured considerable attentions in recent years on account of their unique and promising electrical transport properties, including semiconductor features with direct and desirable energy band structures, outstanding carrier mobilities, controllable and tunable characteristics under applied strain, electric and magnetic fields, highly anisotropic phenomena along both in-plane and out-plane directions, topological transmission states, and negative Poisson’s ratio. Accordingly, a number of investigations on this family of 2D materials have been conducting rapidly, while initiating great potential and new opportunities on the nanoscale science and applications in optoelectronic, magneto-electronics, thermo-electronic, ferroelectric, topological spintronics, and so on. Herein, a specific review is provided with systematical summarizations and refinements on the recent advances of the electrical transport in group-V elemental ultrathin 2D layers from the blossoming field of research, while comprehensive discussion and some recommendations are put forward, with an expectation of broadening and deepening understanding of the family of 2D layers. Lastly, we provide critical motivation and challenge for future explorations in this promising territory.
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- 2020
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27. Less efficacy of valproic acid monotherapy may be caused by neural excitatory rebound in focal seizures
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Zilu Zhu, Hongmiao Zhang, Yusheng Tong, Yuchen Liu, Zhengyu Cui, Ying Mao, Zehan Wu, Deheng Wang, Shize Jiang, Xiang Zou, Zun-Ji Ke, Liang Chen, and Yu Guo
- Subjects
Neural activity ,Awake craniotomy ,Valproic Acid ,business.industry ,Excitatory postsynaptic potential ,Medicine ,High density ,lipids (amino acids, peptides, and proteins) ,Local field potential ,Pharmacology ,Inhibitory postsynaptic potential ,business ,medicine.drug - Abstract
Valproic acid (VPA) represents one of the most efficient antiepileptic drugs (AEDs) with either general or focal seizures, but a certain percentage of patients are not recovered or even worse, the mechanism under this phenomenon remains unclear. Here, we retrospectively reviewed 16 patients who received awake craniotomy surgery. Intro-operative high density electrocorticogram (ECoG) was used to record the local field potential (LFP) response to VPA treatment. We found the less efficacy of VPA monotherapy was associated with ECoG spectrum power shift from higher to lower frequency after VPA injection, together with increased synchronization of the LFP. Furthermore, we established the computational model to testify the hypothesis that the ineffectivity of VPA may be caused by excitatory dynamic rebound during the inhibitory power increasing. In addition to test the hypothesis, we employed the mice with Kanic Acid (KA)-induced epileptic model to confirm that it would be inhibited by VPA on behavior and neural activity. Also, the neural activity shows significant rebound on spike firing. Then we discovered that the LFP would increase the power spectral density in multiple wave bands after the VPA delivers. These findings suggest that less efficacy of valproic acid monotherapy in focal seizures may be caused by neural excitatory rebound which mediated by elevated inhibitory power.
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- 2021
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28. Progress in the synthesis of 2D black phosphorus beyond exfoliation
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Yuqian Zhao, Zehan Wu, Zhaoying Dang, and Jianhua Hao
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General Physics and Astronomy - Abstract
A considerable number of recent research have focused on two-dimensional (2D) black phosphorus (BP) since it was successfully prepared through mechanical exfoliation in 2014. After scaling down, BP with atomistic thickness shows fascinating semiconducting features with layer-dependent direct bandgap and high carrier mobility. The synthesis of high-quality few-layer BP thin films is critical to investigate their distinctive crystal structure, fundamental characteristics, as well as the potential applications in electronics, biomedicine, energy storage, photonics, and optoelectronics. Therefore, this review provides an overview of mono- and few-layer BP topic in the synthesis methods beyond exfoliation, including thinning treatments accompanied to exfoliation, conversion from red phosphorus to BP, and direct growth techniques. We summarize various attempts to control the BP sample's thickness and lateral dimensions during the synthesis. Furthermore, we discuss the current challenges and perspectives of large-scale growth of ultrathin BP which has been a bottleneck hindering wafer-scale device's development in this field. We hope to provide an insight into exploring some potential approaches practicable to synthesize high quality BP thin films utilized for developing high-performance nano-electronics and photonics, which may accelerate the progress of 2D BP toward real applications.
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- 2022
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29. Revealing photovoltaic behavior in 2D hybrid perovskite ferroelectric single-crystalline microwire arrays for self-powered photodetectors
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Ran Ding, Yongxin Lyu, Yuqian Zhao, Zehan Wu, Feng Guo, Weng Fu Io, Sin-Yi Pang, Jianfeng Mao, Man-Chung Wong, Lok Wing Wong, Cenqi Yan, Jiangsheng Yu, Jiong Zhao, Gang Li, and Jianhua Hao
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Physics and Astronomy (miscellaneous) ,General Materials Science ,Energy (miscellaneous) - Published
- 2022
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30. Decoding continuous kinetic information of grasp from stereo-electroencephalographic (SEEG) recordings
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Xiaolong Wu, Guangye Li, Shize Jiang, Scott Wellington, Shengjie Liu, Zehan Wu, Benjamin Metcalfe, Liang Chen, and Dingguo Zhang
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Cellular and Molecular Neuroscience ,Hand Strength ,Brain-Computer Interfaces ,Biomedical Engineering ,Linear Models ,Humans ,Electroencephalography ,Neural Networks, Computer - Abstract
Objective. Brain–computer interfaces (BCIs) have the potential to bypass damaged neural pathways and restore functionality lost due to injury or disease. Approaches to decoding kinematic information are well documented; however, the decoding of kinetic information has received less attention. Additionally, the possibility of using stereo-electroencephalography (SEEG) for kinetic decoding during hand grasping tasks is still largely unknown. Thus, the objective of this paper is to demonstrate kinetic parameter decoding using SEEG in patients performing a grasping task with two different force levels under two different ascending rates. Approach. Temporal-spectral representations were studied to investigate frequency modulation under different force tasks. Then, force amplitude was decoded from SEEG recordings using multiple decoders, including a linear model, a partial least squares model, an unscented Kalman filter, and three deep learning models (shallow convolutional neural network, deep convolutional neural network and the proposed CNN+RNN neural network). Main results. The current study showed that: (a) for some channel, both low-frequency modulation (event-related desynchronization (ERD)) and high-frequency modulation (event-related synchronization) were sustained during prolonged force holding periods; (b) continuously changing grasp force can be decoded from the SEEG signals; (c) the novel CNN+RNN deep learning model achieved the best decoding performance, with the predicted force magnitude closely aligned to the ground truth under different force amplitudes and changing rates. Significance. This work verified the possibility of decoding continuously changing grasp force using SEEG recordings. The result presented in this study demonstrated the potential of SEEG recordings for future BCI application.
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- 2021
31. Lanthanide near-infrared emission and energy transfer in layered WS2/MoS2 heterostructure
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Jianhua Hao, Yongxin Lyu, Shiqing Xu, Zehan Wu, and Gongxun Bai
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Lanthanide ,Materials science ,business.industry ,Doping ,Heterojunction ,02 engineering and technology ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,0104 chemical sciences ,Ion ,Condensed Matter::Materials Science ,symbols.namesake ,symbols ,Optoelectronics ,General Materials Science ,Wafer ,van der Waals force ,Thin film ,Photonics ,0210 nano-technology ,business - Abstract
Lanthanide ions have attracted great attention due to their distinct photonic properties. The optoelectronic properties and device performance are greatly affected by the interfacial coupling between the layered van der Waals heterostructure, fabricated with two or more transition metal dichalcogenide (TMD) layers. In this work, lanthanide-doped WS2/MoS2 layered heterostructures have been constructed through two synthesis steps. The doped thin films are highly textured nanosheets on wafers. Importantly, the as-prepared heterostructure exhibits efficient near-infrared emission in the range of the telecommunication window, owing to energy transfer between lanthanide ions in the two TMD layers. The use of the layered heterostructure allows the decrease of deleterious cross-relaxation due to homogeneous doping or concentration quenching. The energy transfer process was further elaborated in this work. The results suggest that lanthanide ions can effectively extend the emission band of TMD thin films and their heterostructures. The doped TMD heterostructure is highly favourable for constructing atomically thin near-infrared photonic devices.
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- 2019
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32. The correlation between accumulation of amyloid beta with enhanced neuroinflammation and cognitive impairment after intraventricular hemorrhage
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Fan Zhao, Yimin Shi, Zehan Wu, Renqing Zhu, Liang Chen, Xiang Zou, and Cong-Lin Jiang
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0303 health sciences ,medicine.medical_specialty ,biology ,business.industry ,Amyloid beta ,Morris water navigation task ,Cognition ,General Medicine ,medicine.disease ,Ferritin ,03 medical and health sciences ,0302 clinical medicine ,Intraventricular hemorrhage ,Endocrinology ,Internal medicine ,medicine ,biology.protein ,Hemoglobin ,business ,Pathological ,030217 neurology & neurosurgery ,Neuroinflammation ,030304 developmental biology - Abstract
OBJECTIVEIntraventricular hemorrhage (IVH) is found in approximately 40% of intracerebral hemorrhages and is associated with increased mortality and poor functional outcome. Cognitive impairment is one of the complications and occurs due to various pathological changes. Amyloid beta (Aβ) accumulation and neuroinflammation, and the Alzheimer disease–like pathology, may contribute to cognitive impairment. Iron, the degradation product of hemoglobin, correlates with Aβ. In this study, the authors investigated the correlation between Aβ accumulation with enhanced neuroinflammation and cognitive impairment in a rat model of IVH.METHODSNine male Sprague-Dawley rats underwent an intraventricular injection of autologous blood. Another 9 rats served as controls. Cognitive function was assessed by the Morris water maze and T-maze rewarded alternation tests. Biomarkers of Aβ accumulation, neuroinflammation, and c-Jun N-terminal kinase (JNK) activation were examined.RESULTSCognitive function was impaired in the autologous blood injection group compared with the control group. In the blood injection group, Aβ accumulation was observed, with a co-located correlation between iron storage protein ferritin and Aβ. Beta-site amyloid precursor protein cleaving enzyme–1 (BACE1) activity was elevated. Microgliosis and astrogliosis were observed in hippocampal CA1, CA2, CA3, and dentate gyrus areas, with elevated proinflammatory cytokines tumor necrosis factor–α and interleukin-1. Protein levels of phosphorylated JNK were increased after blood injection.CONCLUSIONSAβ accumulation and enhanced neuroinflammation have a role in cognitive impairment after IVH. A potential therapeutic method requires further investigation.
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- 2019
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33. Centimeter‐scale growth of two‐dimensional layered high‐mobility bismuth films by pulsed laser deposition
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Zhibin Yang, Yongxin Lyu, Zehan Wu, and Jianhua Hao
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Centimeter ,Materials science ,Scale (ratio) ,chemistry ,business.industry ,Optoelectronics ,chemistry.chemical_element ,business ,Pulsed laser deposition ,Bismuth - Published
- 2019
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34. Phase-Amplitude Coupling between Neuronal Wideband Low-Frequency Oscillations and Broadband Gamma Activity
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Xiangyang Zhu, Peter Brunner, Tao Xie, Zehan Wu, Liang Chen, and Xinjun Sheng
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Coupling ,Physics ,0303 health sciences ,Phase (waves) ,Neural engineering ,Topology ,03 medical and health sciences ,0302 clinical medicine ,Narrowband ,Broadband ,Premovement neuronal activity ,Wideband ,Frequency modulation ,030217 neurology & neurosurgery ,030304 developmental biology - Abstract
Phase-amplitude coupling (PAC) between the phase of low-frequency oscillations and the power of high-frequency activity plays a functional role in neuronal computation and information transfer. Traditional Hilbert transform-based PAC methods assume that neuronal activity is narrowband, sinusoidal, and sustained. However, natural neuronal signals often violate these three assumptions, creating a potential confound for the interpretation of PAC results. In this study, we present a new method, called Tau-Modulation, that does not require these assumptions to be met. We use this method to identify task-relevant neuronal networks in human electrocorticographic signals. Our results show that Tau-Modulation can identify these networks and characterize the strength and frequency of wideband low-frequency coupling with broadband gamma activity. Thus, Tau-Modulation might provide for a robust approach to analyzing neuronal signals and pave the way for new insights on brain functions.
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- 2021
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35. Multifunctional Crosslinking-Enabled Strain-Regulating Crystallization for Stable, Efficient α-FAPbI
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Hengkai, Zhang, Zhiliang, Chen, Minchao, Qin, Zhiwei, Ren, Kuan, Liu, Jiaming, Huang, Dong, Shen, Zehan, Wu, Yaokang, Zhang, Jianhua, Hao, Chun-Sing, Lee, Xinhui, Lu, Zijian, Zheng, Wei, Yu, and Gang, Li
- Abstract
α-Formamidinium lead triiodide (α-FAPbI
- Published
- 2021
36. Excess PbI 2 Management via Multimode Supramolecular Complex Engineering Enables High‐Performance Perovskite Solar Cells
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Hengkai Zhang, Wei Yu, Junxue Guo, Chao Xu, Zhiwei Ren, Kuan Liu, Guang Yang, Minchao Qin, Jiaming Huang, Zhiliang Chen, Qiong Liang, Dong Shen, Zehan Wu, Yaokang Zhang, Hrisheekesh Thachoth Chandran, Jianhua Hao, Ye Zhu, Chun‐sing Lee, Xinhui Lu, Zijian Zheng, Jinsong Huang, and Gang Li
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Renewable Energy, Sustainability and the Environment ,General Materials Science - Published
- 2022
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37. Automated intraoperative central sulcus localization and somatotopic mapping using median nerve stimulation
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Tao Xie, Zehan Wu, Gerwin Schalk, Yusheng Tong, Alessandro Vato, Nataly Raviv, Qinglong Guo, Huanpeng Ye, Xinjun Sheng, Xiangyang Zhu, Peter Brunner, and Liang Chen
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Cerebral Cortex ,Brain Mapping ,Cellular and Molecular Neuroscience ,Biomedical Engineering ,Humans ,Electrocorticography ,Craniotomy ,Median Nerve - Abstract
Objective. Accurate identification of functional cortical regions is essential in neurological resection. The central sulcus (CS) is an important landmark that delineates functional cortical regions. Median nerve stimulation (MNS) is a standard procedure to identify the position of the CS intraoperatively. In this paper, we introduce an automated procedure that uses MNS to rapidly localize the CS and create functional somatotopic maps. Approach. We recorded electrocorticographic signals from 13 patients who underwent MNS in the course of an awake craniotomy. We analyzed these signals to develop an automated procedure that determines the location of the CS and that also produces functional somatotopic maps. Main results. The comparison between our automated method and visual inspection performed by the neurosurgeon shows that our procedure has a high sensitivity (89%) in identifying the CS. Further, we found substantial concordance between the functional somatotopic maps generated by our method and passive functional mapping (92% sensitivity). Significance. Our automated MNS-based method can rapidly localize the CS and create functional somatotopic maps without imposing additional burden on the clinical procedure. With additional development and validation, our method may lead to a diagnostic tool that guides neurosurgeons and reduces postoperative morbidity in patients undergoing resective brain surgery.
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- 2022
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38. Detection of human white matter activation and evaluation of its function in movement decoding using stereo-electroencephalography (SEEG)
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Liang Chen, Xiangyang Zhu, Zehan Wu, Sivylla E. Paraskevopoulou, Shize Jiang, Zhen Fan, Yang Xu, Meng Wang, Dingguo Zhang, Zixuan Wei, Shengjie Liu, Guohong Chai, and Guangye Li
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Cerebral Cortex ,medicine.diagnostic_test ,business.industry ,Computer science ,Movement (music) ,Movement ,Biomedical Engineering ,Pattern recognition ,Electroencephalography ,Human brain ,White Matter ,Stereoelectroencephalography ,White matter ,Cellular and Molecular Neuroscience ,medicine.anatomical_structure ,medicine ,Humans ,Artificial intelligence ,Gray Matter ,business ,Gray (horse) ,Decoding methods ,Brain–computer interface - Abstract
Objective. White matter tissue takes up approximately 50% of the human brain volume and it is widely known as a messenger conducting information between areas of the central nervous system. However, the characteristics of white matter neural activity and whether white matter neural recordings can contribute to movement decoding are often ignored and still remain largely unknown. In this work, we make quantitative analyses to investigate these two important questions using invasive neural recordings.Approach. We recorded stereo-electroencephalography (SEEG) data from 32 human subjects during a visually-cued motor task, where SEEG recordings can tap into gray and white matter electrical activity simultaneously. Using the proximal tissue density method, we identified the location (i.e. gray or white matter) of each SEEG contact. Focusing on alpha oscillatory and high gamma activities, we compared the activation patterns between gray matter and white matter. Then, we evaluated the performance of such white matter activation in movement decoding.Main results. The results show that white matter also presents activation under the task, in a similar way with the gray matter but at a significantly lower amplitude. Additionally, this work also demonstrates that combing white matter neural activities together with that of gray matter significantly promotes the movement decoding accuracy than using gray matter signals only.Significance. Taking advantage of SEEG recordings from a large number of subjects, we reveal the response characteristics of white matter neural signals under the task and demonstrate its enhancing function in movement decoding. This study highlights the importance of taking white matter activities into consideration in further scientific research and translational applications.
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- 2021
39. Supramolecular Complex Engineering Enables Stable and High Performance α-FAPbI 3 Based Perovskite Solar Cells
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Guang Yang, Zhiliang Chen, Gang Li, Dong Shen, Qiong Liang, Jinsong Huang, Zijian Zheng, Kuan Liu, Minchao Qin, Ye Zhu, Hrisheekesh Thachoth Chandran, Chun-Sing Lee, Hengkai Zhang, Zhiwei Ren, Jiaming Huang, Zehan Wu, Yaokang Zhang, Wei Yu, Chao Xu, Xinhui Lu, and Jianhua Hao
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chemistry.chemical_compound ,Materials science ,Strain engineering ,chemistry ,Passivation ,Chemical engineering ,Ionic liquid ,Relaxation (NMR) ,Photodissociation ,Supramolecular chemistry ,Ionic bonding ,Perovskite (structure) - Abstract
Excess PbI2 management is critical to the performance and stability of perovskite solar cells (PSCs). However, typical post treatment method remains the nature of instability induced by the photolysis of PbI2. Herein, by forming robust self-assembled supramolecules ([BMIM]PbI2X5 and [BMIM]PbX3) with 1-butyl-3-methylimidazolium based ionic liquids ([BMIM]X), we report a novel “Ionic Liquid assisted Supramolecular Complex engineering” (ILaSC) approach to effectively modulate the unreacted PbI2. The formation process and mechanism of supramolecules are elucidated. With effective Pb interstitial defects passivation and tensile strain relaxation simultaneously, the ILaSC approach achieves significant enhancements in both PCE (from 21.9% to 23.5%) and device stability (retaining 95% of the initial PCE after 4080 h in ambient dry-air storage, and 80% after 1400 h continuous light illumination). The generality of the supramolecular complex engineering methodology in broader ionic salt systems is further demonstrated, representing a new direction towards highly stable and efficient PSCs.
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- 2021
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40. Manipulating Crystallization Kinetics in High‐Performance Blade‐Coated Perovskite Solar Cells via Cosolvent‐Assisted Phase Transition
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Qiong Liang, Kuan Liu, Mingzi Sun, Zhiwei Ren, Patrick W. K. Fong, Jiaming Huang, Minchao Qin, Zehan Wu, Dong Shen, Chun‐Sing Lee, Jianhua Hao, Xinhui Lu, Bolong Huang, and Gang Li
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Mechanics of Materials ,Mechanical Engineering ,General Materials Science - Abstract
Manipulating the perovskite solidification process, including nucleation and crystal growth, plays a critical role in controlling film morphology and thus affects the resultant device performance. In this work, a facile and effective ethyl alcohol (EtOH) cosolvent strategy is demonstrated with the incorporation of EtOH into perovskite ink for high-performance room-temperature blade-coated perovskite solar cells (PSCs) and modules. Systematic real-time perovskite crystallization studies uncover the delicate perovskite structural evolutions and phase-transition pathway. Time-resolved X-ray diffraction and density functional theory calculations both demonstrate that EtOH in the mixed-solvent system significantly promotes the formation of an FA-based precursor solvate (FA
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- 2022
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41. Large‐Area Tellurium/Germanium Heterojunction Grown by Molecular Beam Epitaxy for High‐Performance Self‐Powered Photodetector
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Maohai Xie, Zehan Wu, Jianhua Hao, Ran Ding, Shu Ping Lau, Beining Zheng, Jianfeng Mao, and Feng Guo
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Materials science ,chemistry ,business.industry ,Optoelectronics ,Photodetector ,chemistry.chemical_element ,Heterojunction ,Germanium ,business ,Tellurium ,Atomic and Molecular Physics, and Optics ,Electronic, Optical and Magnetic Materials ,Molecular beam epitaxy - Published
- 2021
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42. iEEGview: An Open-source Multifunction GUI-based Matlab Toolbox for Localization and Visualization of Human Intracranial Electrodes
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Guangye Li, Shize Jiang, Liang Chen, Chen Chen, Gerwin Schalk, Peter Brunner, Zehan Wu, and Dingguo Zhang
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Computer science ,0206 medical engineering ,Biomedical Engineering ,02 engineering and technology ,Article ,03 medical and health sciences ,Cellular and Molecular Neuroscience ,0302 clinical medicine ,Software ,Brain segmentation ,Humans ,Computer vision ,Projection (set theory) ,MATLAB ,computer.programming_language ,Brain Mapping ,business.industry ,Process (computing) ,Brain ,Electroencephalography ,020601 biomedical engineering ,Pipeline (software) ,Magnetic Resonance Imaging ,Toolbox ,Visualization ,Electrodes, Implanted ,Artificial intelligence ,Electrocorticography ,business ,computer ,030217 neurology & neurosurgery - Abstract
Objective The precise localization of intracranial electrodes is a fundamental step relevant to the analysis of intracranial electroencephalography (iEEG) recordings in various fields. With the increasing development of iEEG studies in human neuroscience, higher requirements have been posed on the localization process, resulting in urgent demand for more integrated, easy-operation and versatile tools for electrode localization and visualization. With the aim of addressing this need, we develop an easy-to-use and multifunction toolbox called iEEGview, which can be used for the localization and visualization of human intracranial electrodes. Approach iEEGview is written in Matlab scripts and implemented with a GUI. From the GUI, by taking only pre-implant MRI and post-implant CT images as input, users can directly run the full localization pipeline including brain segmentation, image co-registration, electrode reconstruction, anatomical information identification, activation map generation and electrode projection from native brain space into common brain space for group analysis. Additionally, iEEGview implements methods for brain shift correction, visual location inspection on MRI slices and computation of certainty index in anatomical label assignment. Main results All the introduced functions of iEEGview work reliably and successfully, and are tested by images from 28 human subjects implanted with depth and/or subdural electrodes. Significance iEEGview is the first public Matlab GUI-based software for intracranial electrode localization and visualization that holds integrated capabilities together within one pipeline. iEEGview promotes convenience and efficiency for the localization process, provides rich localization information for further analysis and offers solutions for addressing raised technical challenges. Therefore, it can serve as a useful tool in facilitating iEEG studies.
- Published
- 2019
43. Effective Piezo‐Phototronic Enhancement of Flexible Photodetectors Based on 2D Hybrid Perovskite Ferroelectric Single‐Crystalline Thin‐Films
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Feng Guo, Zehan Wu, Man-Chung Wong, Weng Fu Io, Yuqian Zhao, Yongxin Lyu, Sin Yi Pang, Jianfeng Mao, Ran Ding, and Jianhua Hao
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Piezoelectric coefficient ,Materials science ,business.industry ,Mechanical Engineering ,Photodetector ,02 engineering and technology ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,Piezoelectricity ,Ferroelectricity ,0104 chemical sciences ,Responsivity ,Piezoresponse force microscopy ,Semiconductor ,Mechanics of Materials ,Optoelectronics ,General Materials Science ,0210 nano-technology ,business ,Perovskite (structure) - Abstract
2D hybrid perovskites are very attractive for optoelectronic applications because of their numerous exceptional properties. The emerging 2D perovskite ferroelectrics, in which are the coupling of spontaneous polarization and piezoelectric effects, as well as photoexcitation and semiconductor behaviors, have great appeal in the field of piezo-phototronics that enable to effectively improve the performance of optoelectronic devices via modulating the electro-optical processes. However, current studies on 2D perovskite ferroelectrics focus on bulk ceramics that cannot endure irregular mechanical deformation and limit their application in flexible optoelectronics and piezo-phototronics. Herein, we synthesize ferroelectric EA4 Pb3 Br10 single-crystalline thin-films (SCFs) for integration into flexible photodetectors. The in-plane multiaxial ferroelectricity is evident within the EA4 Pb3 Br10 SCFs through systematic characterizations. Flexible photodetectors based on EA4 Pb3 Br10 SCFs are achieved with an impressive photodetection performance. More importantly, optoelectronic EA4 Pb3 Br10 SCFs incorporated with in-plane ferroelectric polarization and effective piezoelectric coefficient show great promise for the observation of piezo-phototronic effect, which is capable of greatly enhancing the photodetector performance. Under external strains, the responsivity of the flexible photodetectors can be modulated by piezo-phototronic effect with a remarkable enhancement up to 284%. Our findings shed light on the piezo-phototronic devices and offer a promising avenue to broaden functionalities of hybrid perovskite ferroelectrics.
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- 2021
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44. Multifunctional Crosslinking‐Enabled Strain‐Regulating Crystallization for Stable, Efficient α‐FAPbI 3 ‐Based Perovskite Solar Cells
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Gang Li, Yaokang Zhang, Zhiliang Chen, Xinhui Lu, Zijian Zheng, Kuan Liu, Dong Shen, Zhiwei Ren, Wei Yu, Chun-Sing Lee, Hengkai Zhang, Jiaming Huang, Minchao Qin, Zehan Wu, and Jianhua Hao
- Subjects
Materials science ,Passivation ,Annealing (metallurgy) ,Mechanical Engineering ,Energy conversion efficiency ,02 engineering and technology ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,Grain size ,0104 chemical sciences ,law.invention ,chemistry.chemical_compound ,chemistry ,Chemical engineering ,Mechanics of Materials ,law ,Ultimate tensile strength ,General Materials Science ,Triiodide ,Crystallization ,0210 nano-technology ,Perovskite (structure) - Abstract
α-Formamidinium lead triiodide (α-FAPbI3 ) represents the state-of-the-art for perovskite solar cells (PSCs) but experiences intrinsic thermally induced tensile strain due to a higher phase-converting temperature, which is a critical instability factor. An in situ crosslinking-enabled strain-regulating crystallization (CSRC) method with trimethylolpropane triacrylate (TMTA) is introduced to precisely regulate the top section of perovskite film where the largest lattice distortion occurs. In CSRC, crosslinking provides in situ perovskite thermal-expansion confinement and strain regulation during the annealing crystallization process, which is proven to be much more effective than the conventional strain-compensation (post-treatment) method. Moreover, CSRC with TMTA successfully achieves multifunctionality simultaneously: the regulation of tensile strain, perovskite defects passivation with an enhanced open-circuit voltage (VOC = 50 mV), and enlarged perovskite grain size. The CSRC approach gives significantly enhanced power conversion efficiency (PCE) of 22.39% in α-FAPbI3 -based PSC versus 20.29% in the control case. More importantly, the control PSCs' instability factor-residual tensile strain-is regulated into compression strain in the CSRC perovskite film through TMTA crosslinking, resulting in not only the best PCE but also outstanding device stability in both long-term storage (over 4000 h with 95% of initial PCE) and light soaking (1248 h with 80% of initial PCE) conditions.
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- 2021
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45. Flexible Solar Cells: Low‐Temperature‐Deposited TiO 2 Nanopillars for Efficient and Flexible Perovskite Solar Cells (Adv. Mater. Interfaces 3/2021)
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Ting Xiao, Jianhua Hao, Hao-Li Zhang, Hong Hu, Zijian Zheng, Chun-Lin Sun, Zehan Wu, Jie Zhao, Peng Sun, Zhongwei Wu, Zhifeng Huang, and Peng Li
- Subjects
Glancing angle deposition ,Materials science ,Mechanics of Materials ,business.industry ,Mechanical Engineering ,Optoelectronics ,business ,Nanopillar ,Perovskite (structure) - Published
- 2021
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46. Low‐Temperature‐Deposited TiO 2 Nanopillars for Efficient and Flexible Perovskite Solar Cells
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Peng Sun, Zijian Zheng, Zehan Wu, Ting Xiao, Peng Li, Zhongwei Wu, Hao-Li Zhang, Hong Hu, Zhifeng Huang, Jianhua Hao, Chun-Lin Sun, and Jie Zhao
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Glancing angle deposition ,Materials science ,Mechanics of Materials ,business.industry ,Mechanical Engineering ,Optoelectronics ,business ,Nanopillar ,Perovskite (structure) - Published
- 2020
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47. Endogenous hormone 2-methoxyestradiol suppresses venous hypertension-induced angiogenesis through up- and down-regulating p53 and id-1
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Ying Mao, Chunjie Yang, Liang Chen, Jianping Song, Xiang Zou, Li Zhang, Wei Zhu, Zehan Wu, and Jie Yuan
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Inhibitor of Differentiation Protein 1 ,Male ,2‐Methoxyestradiol ,p53 ,0301 basic medicine ,Angiogenesis ,arteriovenous malformation ,Down-Regulation ,Models, Biological ,Basal Ganglia ,Umbilical vein ,Rats, Sprague-Dawley ,angiogenesis ,03 medical and health sciences ,0302 clinical medicine ,Cell Movement ,In vivo ,Human Umbilical Vein Endothelial Cells ,Animals ,Humans ,Medicine ,2-Methoxyestradiol ,Gene knockdown ,Neovascularization, Pathologic ,business.industry ,HIF‐1α ,Cell migration ,Original Articles ,Cell Biology ,Hypoxia (medical) ,Hypoxia-Inducible Factor 1, alpha Subunit ,In vitro ,Up-Regulation ,030104 developmental biology ,Hypertension ,Microvessels ,Cancer research ,Molecular Medicine ,Original Article ,Tumor Suppressor Protein p53 ,medicine.symptom ,business ,ID‐1 ,030217 neurology & neurosurgery ,medicine.drug - Abstract
Brain arteriovenous malformations (AVMs) which associate with angiogenesis due to local hypertension, chronic cerebral ischaemia and tissue hypoxia usually lead to haemorrhage, however, the therapeutic medicine for the disease is still lacking. 2‐methoxyestradiol (2‐ME) has been shown effective in the anti‐angiogenic treatment. This study was conducted to examine whether and how 2‐ME could improve the vascular malformations. Intracranial venous hypertension (VH) model produced in adult male Sprague‐Dawley rats and culture of human umbilical vein endothelial cells (HUVECs) at the anoxia condition were used to induce in vivo and in vitro angiogenesis, respectively. Lentiviral vectors of ID‐1 and p53 genes and of their siRNA were intracranially injected into rats and transfected into HUVECs to overexpress and down‐regulate these molecules. 2‐ME treatment not only reduced the in vivo progression of brain tissue angiogenesis in the intracranial VH rats and the in vitro increases in microvasculature formation, cellular migration and HIF‐1α expression induced by anoxia in HUVECs but also reversed the up‐regulation of ID‐1 and down‐regulation of p53 in both the in vivo and in vitro angiogenesis models. All of the anti‐angiogenesis effects of 2‐ME observed in VH rats and anoxic HUVECs were abrogated by ID‐1 overexpression and p53 knockdown. Our data collectively suggest that 2‐ME treatment inhibits hypoxia/anoxia‐induced angiogenesis dependently on ID‐1 down‐regulation and p53 up‐regulation, providing a potential alternative medical treatment for un‐ruptured AVM patients.
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- 2017
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48. The Role of Matrix Metalloproteinase-3 in the Doxycycline Attenuation of Intracranial Venous Hypertension-Induced Angiogenesis
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Yao Zhao, Jianping Song, Peiliang Li, Wei Zhu, Liang Chen, Zehan Wu, Ying Mao, Xiang Zou, Xuanfeng Qin, Peixi Liu, Guo-Yuan Yang, and Jun Huang
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0301 basic medicine ,Intracranial Arteriovenous Malformations ,Male ,Angiogenesis ,Vascular Remodeling ,Stromelysin 1 ,Neovascularization ,03 medical and health sciences ,0302 clinical medicine ,medicine ,Animals ,Humans ,Tube formation ,Doxycycline ,Metalloproteinase ,Gene knockdown ,Neovascularization, Pathologic ,business.industry ,Rats ,Vascular endothelial growth factor A ,030104 developmental biology ,Cancer research ,Surgery ,Matrix Metalloproteinase 3 ,Neurology (clinical) ,medicine.symptom ,Intracranial Hypertension ,business ,030217 neurology & neurosurgery ,medicine.drug - Abstract
BACKGROUND The molecular mechanism of brain arteriovenous malformation (BAVM) is largely unknown. Intracranial venous hypertension (VH) may enhance focal angiogenesis and promote BAVM development and progression. A rat VH model effectively simulates the hemodynamic microenvironment of this disease. OBJECTIVE To explore the effect of doxycycline in VH-related angiogenesis, as well as the role of matrix metalloproteinase-3 (MMP-3) and other molecular factors. METHODS A rat VH model was generated by common carotid artery and distal external jugular vein anastomosis. Microvessel density (MVD) in the perisinus area and expression of MMP-3/2/9, VEGF, TIMP-1, TGF-β, and HIF-1α were examined, with and without daily doxycycline treatment for 4 wk. The effects of doxycycline were verified in Vitro using human brain microvascular endothelial cells (HBMECs). MMP-3 overexpression or knockdown in HBMECs was used to confirm the role of MMP-3 in cell functions. RESULTS MVD in the perisinus cortex was greatly increased after VH. Doxycycline decreased MVD, suppressed MMP-3 overexpression, and reduced VEGF, TGF-β, and TIMP-1 levels compared with the controls (P < .05). In Vitro, doxycycline decreased HBMEC migration, tube formation, and the mRNA, protein, and enzymatic activity levels of MMP-3. MMP-3 overexpression in HBMECs promoted migration, while knockdown of MMP-3 significantly attenuated proliferation, migration, and tube formation (P < .05). CONCLUSION Our findings indicate that MMP-3 plays an important role in VH-related angiogenesis and the promotion of vascular remodeling. Suppression of MMP-3 overexpression by doxycycline may provide a potential strategy for inhibiting BAVM development.
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- 2017
49. Electrocorticographic Temporal Alteration Mapping: A Clinical Technique for Mapping the Motor Cortex with Movement-Related Cortical Potentials
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Lin Yao, Xiangyang Zhu, Zehan Wu, Ying Mao, Tao Xie, Dario Farina, Xinjun Sheng, Liang Chen, and Dingguo Zhang
- Subjects
0301 basic medicine ,movement-related cortical potentials (MRCP) ,electrocorticography (ECoG) ,Direct Electrocortical Stimulation ,IMAGERY ,Brain mapping ,lcsh:RC321-571 ,03 medical and health sciences ,Epilepsy ,Functional brain ,0302 clinical medicine ,OSCILLATIONS ,medicine ,motor cortex mapping ,lcsh:Neurosciences. Biological psychiatry. Neuropsychiatry ,FINGER MOVEMENTS ,EPILEPSY ,Original Research ,Science & Technology ,General Neuroscience ,DESYNCHRONIZATION ,AREA ,Significant difference ,Neurosciences ,HUMANS ,TASKS ,1702 Cognitive Science ,medicine.disease ,Frequency spectrum ,LANGUAGE CORTEX ,Awake craniotomy ,030104 developmental biology ,medicine.anatomical_structure ,intraoperative ,Neurosciences & Neurology ,VOLUNTARY MOVEMENTS ,1109 Neurosciences ,Psychology ,Life Sciences & Biomedicine ,Neuroscience ,030217 neurology & neurosurgery ,Motor cortex - Abstract
In this work, electrocorticographic temporal alteration mapping (ETAM) was proposed for motor cortex mapping by utilizing movement-related cortical potentials (MRCPs) within [0.05 3] Hz low frequency band. This MRCP waveform-based temporal domain approach was compared with the state-of-the-art electrocorticographic frequency alteration mapping (EFAM), which was based on high frequency spectrum dynamics. Five patients (2 epilepsy cases and 3 tumor cases) were enrolled in this study. Each patient had intraoperative direct electrocortical stimulation (DECS) procedure for motor cortex localization, and the patient was required to perform simple brisk wrist extension task during awake craniotomy surgery. Cross-validation results shown that the proposed ETAM method had a high performance in sensitivity (81.82%) and specificity (94.33%) for identifying sites which exhibited positive DECS motor responses. No significant difference in sensitivity was observed between ETAM and EFAM methods. However, the proposed ETAM was much higher in specificity as compared with EFAM (94.33% vs. 86.08%). Our results indicated that for the intraoperative functional brain mapping, ETAM was a promising novel approach for motor cortex localization and had a great potential to reduce the needs for cortical electrical stimulation.
- Published
- 2017
50. Long-Term Outcomes of Surgical Treatment in 181 Patients with Supratentorial Cerebral Cavernous Malformation-Associated Epilepsy
- Author
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Jianping Song, Liang Chen, Zehan Wu, Ying Mao, Shize Jiang, and Kangmin He
- Subjects
Adult ,Male ,medicine.medical_specialty ,Hemangioma, Cavernous, Central Nervous System ,Adolescent ,Kaplan-Meier Estimate ,03 medical and health sciences ,Epilepsy ,Young Adult ,0302 clinical medicine ,medicine ,Long term outcomes ,Humans ,Young adult ,Surgical treatment ,Proportional Hazards Models ,Retrospective Studies ,business.industry ,Proportional hazards model ,Retrospective cohort study ,Middle Aged ,medicine.disease ,Confidence interval ,Surgery ,Treatment Outcome ,030220 oncology & carcinogenesis ,Hemosiderin ,Female ,Neurology (clinical) ,business ,030217 neurology & neurosurgery ,Follow-Up Studies - Abstract
Objective To evaluate the efficacy of surgery as a treatment for supratentorial cerebral cavernous malformation–associated epilepsy (SCCMAE) and determine the factors that influence outcomes. Methods During the 5-year period from 2005 to 2009, this study included 181 consecutive patients who were diagnosed with SCCMAE and surgically treated in a single institution. Each patient was followed up for at least 5 years postoperatively. A time-to-event analysis was performed using Kaplan-Meier curves and Cox regression models to evaluate the associated risk factors. Results The age at seizure onset was 30.6 ± 14.3 years, and the age at the time of surgery was 33.4 ± 14.6 years. The female/male ratio was 0.81:1. The mean diameter of the cerebral cavernous malformations (CCMs) was 2.0 cm. For CCMs involving eloquent brain areas, the CCM was removed with (in 14 cases) or without (in 28 lesions) the peripheral hemosiderin. None of the patients had long-term neurologic disabilities. An Engel class I outcome was achieved in 89.0%, 83.4%, 81.8%, and 80.1% of the patients after 6 months, 1 year, 2.5 years, and 5-years of follow-up, respectively. In patients who were class I after 1 year, the prevalence of seizure remission 5 years postoperatively was 96.0% (95% confidence interval, 94.4%–97.6%). Conclusions This study supports the efficacy of using surgery to treat SCCMAE. A shorter duration of preoperative epilepsy was associated with better seizure control after surgery, and patient status at the 1-year follow-up was a reliable indicator of long-term Engel class I epilepsy control.
- Published
- 2017
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