Improved Pseudocapacitive Performance of Graphene Architectures Modulating by Nitrogen/Phosphorus Dual-Doping and Steam- Activation

Chaonan Wang,Junhong Zhao,Shengyun Luo,Xu Yu 한국고분자학회 2021 Macromolecular Research Vol.29 No.9

Steam-assistant nitrogen (N) and phosphorus (P) co-doping of graphene (s-NPG) architectures are constructed by a facile chemical converted method and thermal activation. Steam-activation treatment can provide abundant porous structure for fast ion diffusion and expose more electrochemical active-sites for surface faradic reaction. The wrinkled surface of S-NPG with a large surface area is probed by microscopic analysis. The spectroscopic analysis confirms the existence of pyridinic- N and C-P-O bonds for s-NPG, which are the dominant electroactive sites for accommodating the protons or charges. Therefore, s-NPG exhibits a high specific capacitance of 317 F g-1 at 1 A g-1 with a good rate capability of 87% and cyclic stability of 97.7% after 20,000 cycles. The excellent pseudocapacitive behavior can be attributed to the synergistic effect of hierarchical structure with and surface modification by N and P dual-doping. The simple steam-assistant treatment can be a potential way to construct the hierarchically structured electrode materials for supercapacitors.

Activated carbon fibers derived from natural cattail fibers for supercapacitors

Chaonan Wang,Lijun Bai,Feng Zhao,Lizhong Bai 한국탄소학회 2022 Carbon Letters Vol.32 No.3

The electrochemical capacitive properties of biomass-derived activated carbons are closely dependent on their microscopic structures. Here, activated carbon fibers (ACFs) were prepared from natural cattail fibers by carbonization and further chemical activation. The activation temperature affected on the microscopic structures and electrochemical properties of the activated carbon fibers. The results show that the optimum activation temperature is 800 °C. And the as-prepared ACF- 800 possesses high micropore specific surface area of 710.4 m2 g? 1 and micropore volume of 0.313 cm3 g? 1, respectively. For supercapacitor applications, the ACF-800 displays a high specific capacitance of 249 F g? 1 at a current density of 0.05 A g? 1, excellent rate performance and cycle stability in a three-electrode system. The excellent electrochemical performance indicated that the obtained activated carbon fibers could be a promising electrode material in supercapacitor.

Short-circuit protection method for medium-voltage SiC MOSFET based on gate-source voltage detection

Wang, Zhankuo,Tong, Chaonan,Huang, Weichao The Korean Institute of Power Electronics 2020 JOURNAL OF POWER ELECTRONICS Vol.20 No.4

During the short-circuit fault of a two-level bridge converter based on silicon carbide (SiC) metal-oxide-semiconductor field-effect transistors (MOSFETs), the SiC MOSFETs may fail within a few microseconds without short-circuit protection. The short-circuit protection of SiC MOSFETs is an essential feature for improving the reliability of converters. This study proposes an improved short-circuit protection method for medium-voltage SiC MOSFETs subjected to shoot-through conditions. In the protection method, the gate-source voltage of the SiC MOSFETs in a half bridge is detected to determine whether a shoot-through short circuit occurs or not. A desaturation protection circuit based on V_DS measurement for a short circuit is also designed for overcurrent. The protection circuit's validity is verified by the experimental results. Compared with conventional commercial driver integrated circuits, the proposed method can detect and turn off SiC MOSFETs in 0.2 ㎲ under the shoot-through condition. Desaturation protection can be completed in 0.5 ㎲ when overcurrent occurs.

Prediction of rolling bearing performance degradation based on sae and TCNattention models

Yaping Wang,Dekang Hou,Di Xu,Sheng Zhang,Chaonan Yang 대한기계학회 2023 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.37 No.4

A single feature cannot show the operational state of a bearing during its entire life cycle. Therefore, a rolling bearing performance deterioration prediction method based on an SAE and the TCN-attention model is proposed. The SAE method is used to fuse the timedomain indicator and the frequency-domain indicator to construct the performance degradation characteristic indicator. The evaluation indices are used to comprehensively evaluate multiple performance degradation indices, and the fused feature indices together, to filter out the features that have a good overall performance. Attention is added to the TCN model, and the output state weight of the TCN model is calculated through a scoring function to increase the important information weight and the prediction accuracy. The appropriate network structure and parameter configuration are determined, and the rolling bearing performance degradation prediction model is established. A validation is performed using publicly available datasets from the University of Cincinnati and XJTU-SY. The results show that the method is more sensitive to the critical information part of the long time series than the other models. At the same time, the average absolute error and the root mean square error are minimized, the accuracy of the rolling bearing performance degradation prediction is high, and the model has a strong robustness and generalization abilities. Additionally, the model has practical engineering value for predicting the health status of equipment.

Fabrication of Superior Au–Ag Composites Surface-Enhanced Raman Scattering Active Substrates Based on One-Step Method of Chemical Etching

Li Zhang,Jinghuai Fang,Chaonan Wang,Tian Xu,Yonglong Jin 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2016 NANO Vol.11 No.7

Bimetallic silver–gold composites are currently among the most studied substrates for detection based on surface-enhanced Raman scattering (SERS). Here, we developed Au–Ag composite films as high sensitivity, large-scale, chemically stable and reproducible SERS substrates. Au–Ag composite films were fabricated by chemical etching of Ag–Au alloy leaves with HAuCl4 aqueous solutions. Along with galvanic replacement reaction and dealloying, films with distinct microstructural features exhibit dramatic improvement in the SERS intensity. Especially, the Au–Ag composite films with legible nano-ridges fabricated by alloy leaves of 9 carat present the strongest SERS enhancement. The superior SERS enhancement is attributed to the confluence effect of enhanced local surface plasmon fields and electromagnetic coupling within nanogaps, sharp edges and corners. In addition, results showed that features of the films mightily depend on the initial proportions of Ag–Au alloys.

Computational analysis of welding radial deformation of typical pressure cylindrical shell with ring stiffener

Zhou Hong,Shen Chaonan,Wang Jiangchao 대한조선학회 2022 International Journal of Naval Architecture and Oc Vol.14 No.1

We report on the evaluation of the radial deformation caused by the welding process on a typical pressure cylindrical shell with ring stiffeners. Welding experiments on butt and fillet welding were conducted beforehand, and temperature-dependent material properties were considered. The out-ofplane welding distortion and residual stress were measured using a three-coordinate measuring machine and X-ray diffraction, respectively. Effective thermal elastic plastic FE analysis based on parallel computation technology was performed to examine the mechanical behaviors. Computed results were validated by comparison with experimental measurements. Welding inherent deformations of the examined butt and fillet joints were then evaluated by integrating computed plastic strains. The elastic FE analysis, with welding inherent deformation as mechanical loading, was employed to examine the dimensional variation of the considered pressure cylindrical shell. The influence of ring stiffener on welding radial deformation was also discussed. Moreover, the application of welding sequence modification and inverse deformation was numerically examined with the proposed elastic FE analysis to reduce the welding radial deformation and enhance the fabrication accuracy.

MiR-214 inhibits apoptosis in thyroid epithelial follicular cells induced by amiodarone through the FASL/MAPK pathway

Wen Jing,Deng Chaonan,Shi Lixin,Zhou Shi,Zhang Miao,Hu Xiaoli,Wang Nianxue,Luo Lijuan 대한독성 유전단백체 학회 2022 Molecular & cellular toxicology Vol.18 No.2

Background Hashimoto's thyroiditis (HT), also known as chronic lymphocytic thyroiditis, is one of the most common autoimmune disease (AITD) in clinical practice. It is urgent to explore the mechanism of amiodarone-induced thyroid dysfunction. Objective This study aims to assess the expression levels of miR-214 and FasL in amiodarone contact type of HT, and the effect of miR-214 on cell viability and apoptosis and potential mechanism. Results We found that miR-214 was low expressed in the tissues of amiodarone-treated thyroiditis patients. MiR-214 increased the survival rate of amiodarone-induced thyroid epithelial follicular cells and inhibited apoptosis. Mechanically, we found that miR-214 could bind to FASL and regulate MAPK signaling pathway through FASL. Conclusions Our results suggested that miR-214 could be a potential therapeutic target for Hashimoto's thyroiditis.

PROSPERO's systematic review protocols of traditional Chinese medicine for COVID-19: An overview

Haiyin Hu,Zhaochen Ji,Chaonan Feng,Wentai Pang,Zhe Chen,Junhua Zhang,Hui Wang 한국한의학연구원 2021 Integrative Medicine Research Vol.10 No.-

Background A large number of protocols for Systematic Reviews (SR) of Traditional Chinese Medicine (TCM) for coronavirus disease 2019 (COVID-19) have been registered in the International Prospective Register of Systematic Reviews (PROSPERO). This study aimed to analyze the innovativeness and rigorousness of the SR protocols and make recommendations for the design and implementation of future SRs on TCM for COVID-19. This effort is likely to enhance the value of the produced information and prevent the futility of the research. Methods PROSPERO was searched comprehensively for identifying SRs of TCM for COVID-19 from the inception of the database to August 2020. Two researchers independently screened the literature, extracted the data, and cross-checked the retrieved information for consistency. The following details were recorded: database, registration time, organizations, types of research included, participants, interventions, and outcome measures. All extracted data were analyzed by an overview. The “P - participants, I - interventions, C - controls, and O - outcomes (PICO)” included in the protocols were compared for similarity. The outcomes of the included SR protocols were compared with the newly published Core Outcome Sets (COSs). Results A total of 80 protocols of SR related to TCM for COVID-19 were obtained after a primary search, and finally 71 protocols were included. The majority of the protocols were from China. Thirty-two organizations participated in the protocol registrations, including 11 hospitals and 21 universities/colleges. However, some protocols were not innovative or rigorous enough, as the PICO of some protocols were similar and non-specific, and the searched literature was incomprehensive. In addition, COS is not commonly adopted. Conclusions Registering a protocol of SR is an effective way to ensure the usefulness of the produced information, and to avoid the duplication of research and the wastage of resources. In future SR protocols, it is important to focus on and solve the methodological problems such as non-specific PICO, incomprehensive literature retrieval, and improper outcome measures. Background A large number of protocols for Systematic Reviews (SR) of Traditional Chinese Medicine (TCM) for coronavirus disease 2019 (COVID-19) have been registered in the International Prospective Register of Systematic Reviews (PROSPERO). This study aimed to analyze the innovativeness and rigorousness of the SR protocols and make recommendations for the design and implementation of future SRs on TCM for COVID-19. This effort is likely to enhance the value of the produced information and prevent the futility of the research. Methods PROSPERO was searched comprehensively for identifying SRs of TCM for COVID-19 from the inception of the database to August 2020. Two researchers independently screened the literature, extracted the data, and cross-checked the retrieved information for consistency. The following details were recorded: database, registration time, organizations, types of research included, participants, interventions, and outcome measures. All extracted data were analyzed by an overview. The “P - participants, I - interventions, C - controls, and O - outcomes (PICO)” included in the protocols were compared for similarity. The outcomes of the included SR protocols were compared with the newly published Core Outcome Sets (COSs). Results A total of 80 protocols of SR related to TCM for COVID-19 were obtained after a primary search, and finally 71 protocols were included. The majority of the protocols were from China. Thirty-two organizations participated in the protocol registrations, including 11 hospitals and 21 universities/colleges. However, some protocols were not innovative or rigorous enough, as the PICO of some protocols were similar and non-specific, and the searched literature was incomprehensive. In addition, COS is not commonly adopted. Conclusions Registering a protocol of SR is an effective way to ensure the usefulness of the produced information, and to avoid the duplication of research and the wastage of resources. In future SR protocols, it is important to focus on and solve the methodological problems such as non-specific PICO, incomprehensive literature retrieval, and improper outcome measures.