Microwave heating assisted synthesis of novel SnSe/g-C3N4 composites for effective photocatalytic H2 production

Pengfei Chen,Xiaoquan Dai,Pingxing Xing,Xinyue Zhao,Qingle Zhang,Shifeng Ge,Jianxiao Si,Leihong Zhao,Yiming He 한국공업화학회 2019 Journal of Industrial and Engineering Chemistry Vol.80 No.-

Novel SnSe/g-C3N4 photocatalysts were one-step synthesized via a microwave heating assisted process in35 min with SnSe and melamine as precursors. The as-synthesized SnSe/g-C3N4 worked very well in H2evolution via photocatalysis. Under simulated sunlight, the best SnSe/g-C3N4 sample displayed a H2-production velocity of 1064 mmol g 1 h 1, which is 1.8 folds faster than that of neat g-C3N4. Similarpromotion effect was also observed under visible light. To reveal the nature behind the highphotoactivity, a thorough investigation was performed. XRD and XPS experiments proved the binaryconstitution of the composite. DRS experiment demonstrated that the addition of SnSe improved thephotoabsorption performance. N2-adsorption analysis showed that the SnSe/g-C3N4 photocatalystpresented similar surface area as g-C3N4. TEM experiments showed that some bulk SnSe werespontaneously decomposed to nanoparticles andfinely dispersed in g-C3N4 during the microwaveheating process. These SnSe nanoparticles were believed to be the active phase and constructed aheterojunction structure with g-C3N4, resulting in the enhanced charge separation. This conclusion wasconsidered as the key factor leading to the high H2-evolution performance and was further confirmed bythe PL, EIS, and PC experiments. The present work provides a feasible and rapid method for theconstruction of g-C3N4 based photocatalysts.

Effects of Chlorine Addition to TiO2 Nanorods-Based Perovskite Solar Cells

Dong Zhao,Rendong Wang,Pengfei Wang,Shutao Li,Zhao Li,Meiling Sun,Yunyan Liu,Junshan Xiu 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2019 NANO Vol.14 No.6

Titanium dioxide (TiO2) nanorods (NR) structure and Chlorine substitution is beneficial to the extraction and diffusion of electrons in perovskite solar cells (PSCs). In this work, different concentrations of PbCl2 in perovskite are integrated with TiO2 (NR) to fabricate PSCs. The total thickness of perovskite absorber layer and electron transport layer (ETL) is about 850 nm, and the PSCs exhibit excellent performance. Scanning electron microscope (SEM) and X-ray diffraction (XRD) test reveal that moderate PbCl2 additive improves the perovskite film morphology and crystal quality of perovskite films. Optimal perovskite films with high crystallinity and uniform surface were prepared by adding 3 mol% PbCl2 into perovskite precursor solution, the crystal boundary and defect states are greatly reduced, thus reducing the electrons and holes recombination. The power conversion efficiency (PCE) enhancement of the device with this optimal molar ratio of PbCl2 is over 24% compared with the device without PbCl2.

Excluding molten fluoride salt from nuclear graphite by SiC/glassy carbon composite coating

Zhao He,Jinliang Song,Pengfei Lian,Dongqing Zhang,Zhanjun Liu 한국원자력학회 2019 Nuclear Engineering and Technology Vol.51 No.5

SiC coating and SiC/glassy carbon composite coating were prepared on IG-110 nuclear graphite (ToyoTanso Co., Ltd., Japan) to strengthen its inertness to molten fluoride salt used in molten salt reactor(MSR). Two kinds of modified graphite were obtained and correspondingly named as IG-110-1 and IG-110-2, which referred to modified IG-110 with a single SiC coating and a SiC/glassy carbon compositecoating, respectively. Both structure and property of modified graphite were carefully researched andcontrasted with virgin IG-110. Results indicated that modified graphite presented better comprehensiveproperties such as more compact structure and higher resistance to molten salt infiltration. With theprotection of coatings, the infiltration amounts of fluoride salt into modified graphite were much lessthan that into virgin IG-110 at the same circumstance. Especially, the infiltration amount of fluoride saltinto IG-110-2 under 5 atm was merely 0.26 wt%, which was much less than that into virgin IG-110 under1.5 atm (13.5 wt%) and the critical index proposed for nuclear graphite used in MSR (0.5 wt%). The SiC/glassy carbon composite coating gave rise to highest resistance to molten salt infiltration into IG-110-2,and thus demonstrated it could be a promising protective coating for nuclear graphite used in MSR.

Internal Mammary Sentinel Lymph Node Biopsy after Neoadjuvant Chemotherapy in Breast Cancer

Zhao Bi,Peng Chen,Jingjing Liu,Yanbing Liu,Pengfei Qiu,Qifeng Yang,Weizhen Zheng,Yongsheng Wang 한국유방암학회 2018 Journal of breast cancer Vol.21 No.4

Purpose: The definition of nodal pathologic complete response (pCR) after a neoadjuvant chemotherapy (NAC) just included the evaluation of axillary lymph node (ALN) without internal mammary lymph node. This study aimed to evaluate the feasibility of internal mammary-sentinel lymph node biopsy (IM-SLNB) in patients with breast cancer who underwent NAC. Methods: From November 2011 to 2017, 179 patients with primary breast cancer who underwent operation after NAC were included in this study. All patients received radiotracer injection with modified injection technology. IM-SLNB would be performed on patients with internal mammary sentinel lymph node (IMSLN) visualization. Results: Among the 158 patients with cN+ disease, the rate of nodal pCR was 36.1% (57/158). Among the 179 patients, the visualization rate of IMSLN was 31.8% (57/179) and was 12.3% (7/57) and 87.7% (50/57) among those with cN0 and cN+ disease, respectively. Furthermore, the detection rate of IMSLN was 31.3% (56/179). The success rate of IM-SLNB was 98.2% (56/57). The IMSLN metastasis rate was 7.1% (4/56), and all of them were accompanied by ALN metastasis. The number of positive ALNs in patients with IMSLN metastasis was 3, 6, 8, and 9. The pathology nodal stage had been changed from pN1/ pN2 to pN3b. The pathology stage had been changed from IIA/ IIIA to IIIC. Conclusion: Patients with visualization of IMSLN should perform IM-SLNB after NAC, especially for patients with cN+ disease, in order to complete lymph nodal staging. IM-SLNB could further improve the definition of nodal pCR and guide the internal mammary node irradiation.

Research on Online Reviews Diagnosis’ Effects on Perceptual Information Symmetry

PengFei Qin,JinDan lyu,Yi Zhao ASCONS 2021 INTERNATIONAL JOURNAL OF EMERGING MULTIDISCIPLINAR Vol.5 No.2

Background/Objectives: In this thesis, an empirical study was conducted on consumers’ diagnosis on online reviews in the process of purchasing. Methods/Statistical analysis: In order to verify the viewpoint of this research, this study chooses consumers who have the experience of searching online reviews as the research object, collects data based on a questionnaire from 64 men and 61 women and uses Smart PLS to verify the structural model. Findings: The results of this research are as follows: first, the review diagnosticity sufficiency has positive (+) effects on perceptual information symmetry. Second, the diagnosis on positive online reviews has positive (+) effects on perceptual information symmetry. Third, the diagnosis on negative online reviews has positive (+) effects on perceptual information symmetry. Improvements/Applications: The implications of this study are verifies the effects of the diagnosis of commodities’ online reviews, diagnosis of positive and negative online reviews on consumers’ perceptual information symmetry.

Transient Stability Simulation Analysis of Multi Node Power Network with Variable Speed Pumped Storage Units

Zhao Chong,Wang Longze,Ma Yiyi,Xiang Pengfei,Jiang Siyu,Chen Weidong,Zhang Yan,Li Meicheng 대한전기학회 2023 Journal of Electrical Engineering & Technology Vol.18 No.4

The output characteristics of variable speed pumped storage are different from conventional hydropower and constant speed pumped storage units. The continuous increase of installed capacity of variable speed pumped storage, poses a severe challenge to the safe and stable operation of the local power grid. Proposed in this paper is a kind suitable for multi-node containing variable speed pump machine storage unit electric power network transient stability method, considering the variable speed pumped storage units by the end of the instantaneous failure prone to sudden drop transient power, the power network with more nodes each busbar voltage stable operation as the goal, according to the regional power grid data under typical operation modes, Based on the power system analysis software package, an electromechanical simulation model of the 7-node power grid with variable speed pumped storage unit was established. The influence on the transient stability of a 7-node power grid is analyzed by removing variable speed pumped-storage units and three-phase short-circuit faults. The transient stability of the power grid can be maintained under the conditions of removing variable speed pumped-storage units and three-phase short-circuit faults, but some bus voltages are higher than the specified voltage upper limit. The reactive power compensation device is installed to improve the voltage stability of the power grid system, which can prevent the overvoltage accident caused by the fault of the communication system, achieve the purpose of multi-node power network stability, and improve the safety and stability of the regional power system when the fault occurs.

Synergistic and sustainable activation of peroxymonosulfate by nanoscale MWCNTs-CuFe2O4 as a magnetic heterogeneous catalyst for the efficient removal of levofloxacin

Zhao Jing,Xiao Pengfei 한국화학공학회 2023 Korean Journal of Chemical Engineering Vol.40 No.6

Nanoscale CuFe2O4 was anchored on the surface of multiwalled carbon nanotubes (MWCNTs) as a magnetic heterogeneous catalyst to achieve efficient and sustainable activation of peroxymonosulfate and degradation of levofloxacin through the synergistic effect of the above materials. The catalyst properties were characterized by a series of detection techniques. It was found that the mass ratio of MWCNTs-CuFe2O4, operational parameters and common interfering substances influenced the levofloxacin removal efficiency to a certain extent. This study sheds light on the ultraefficient removal of levofloxacin with the MWCNTs-CuFe2O4(1:3)/peroxymonosulfate system, which has advantages over other reaction systems. More importantly, we propose two pathways of peroxymonosulfate activation, including free radicals and nonfree radicals, in which superoxide radicals and signal oxygen are the main active species. In addition, we observed that the MWCNT surface groups contributed to the peroxymonosulfate activation processes with the generation of extra reactive species. The Fe3+/Fe2+ and Cu2+/Cu+ redox cycles are conducive to the continuous generation of active species. The results of the catalyst recycling test, metal ion leaching test and mineralization test suggested that the fabricated catalyst had excellent catalytic stability, sustainability and mineralization ability. In addition, twenty-one intermediates were detected using liquid chromatography-mass spectrometry, and three possible degradation pathways were further proposed. MWCNTs-CuFe2O4 makes up for the shortcomings of transition metals and single carbon materials in activating peroxymonosulfate to treat wastewater and have significant potential to improve the separation and catalytic capacity of the catalyst. This study provides new ideas for the design of high-performance multiphase catalysts for applications in catalytic oxidation and proposes new insights into the mechanistic investigation.

LIMIT OF FUEL INJECTION RATE IN THE COMMON RAIL SYSTEM UNDER ULTRA-HIGH PRESSURES

Jianhui Zhao,Leonid Grekhov,Pengfei Yue 한국자동차공학회 2020 International journal of automotive technology Vol.21 No.3

The common rail injection system with higher injection pressure can improve injection characteristics. However, relevant researches for injection characteristics under ultra-high pressures are insufficient. In this article, the results of experiments with a maximum injection pressure of 390 MPa for nine different injectors of four types are presented. The experiment showed the existence of supercritical pressure during injection. At pressures below the supercritical pressure, the injection quantity increases with increasing injection pressure, however, when the injection pressure is over supercritical pressure, the injection quantity does not increase. According to the experiment results, the supercritical injection pressure is about 300 ~ 350 MPa. Under ultra-high pressures, fuel is strongly heated and the local sound velocity decreases, and the adiabatic flow velocity reaches the sound velocity. Under supercritical pressure, the injection rate ceases to increase and even begins to fall. The traditional equations for calculating the injection rate cannot correctly describe the injection under ultrahigh pressures. A new mathematic model with considering the fuel heating for describing the injection quantity of compressible fluid was developed, this model is not only suitable for calculating the injection quantity under ultra-high pressures, but under traditional injection pressures.

A Novel Method to Design Single-Sided Left-Handed Metamaterials with a Specific Frequency Band

Renjing Gao,Pengfei shi,Shutian Liu,Jian Zhao 대한금속·재료학회 2014 ELECTRONIC MATERIALS LETTERS Vol.10 No.1

In this paper, a configuration of single-sided left-handed metamaterial (LHM) was constructed by placing one ring and metallic wire rod on the same side of a substrate. Based on this configuration, a novel approach was proposed to design LHM with a specific resonant frequency or two resonant frequencies. A LHM structure with 7.50 GHz resonant frequency was designed by optimizing the sizes of the structure, and the LHM with two resonant frequencies was subsequently constructed by placing two rings and metallic wire rod on the same side of the substrate. The left-handed properties of the proposed structures were verified by both experiments and numerical simulations.

A novel HB-SC-MCCNN model for intelligent fault diagnosis of rolling bearing

Hui Liao,Pengfei Xie,Yan Zhao,Jinfang Gu,Lei Shi,Sier Deng,Hengdi Wang 대한기계학회 2023 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.37 No.12

The incompleteness and lack of bearing fault data have become important problems in bearing fault diagnosis. This paper presents an intelligent fault diagnosis method for rolling bearings based on a similarity clustering multi-channel convolution neural network with the hierarchical branch (HB-SC-MCCNN). First, the relevant features are extracted by MCCNN, and combined with the similarity clustering principle, the accurate binary classification is realized in the case of insufficient labeled data. Second, the similarity clustering module and additional loss are added to the SC-MCCNN network to form a hierarchical-branch network, which simplifies the problem of fault multi-classification into binary classification with multiple steps, and to reduces the dependence on the amount of label data in multi-classification. Finally, based on the self-learning characteristics of HB-SC-MCCNN, the unlabeled data and the missing fault types in the training set are re-labeled to realize the re-training of the network. On the benchmark dataset, the comparison experiment results with several salient deep learning models show that the method proposed in this paper successfully realizes the hierarchical diagnosis of bearing faults and presents more substantial competitiveness in the case of insufficient labeled data and missing fault types.