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DEEP NEURAL NETWORKS COMBINING MULTI-TASK LEARNING FOR SOLVING DELAY INTEGRO-DIFFERENTIAL EQUATIONS
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作者 WANG Chen-yao SHI Feng 《数学杂志》 2025年第1期13-38,共26页
Deep neural networks(DNNs)are effective in solving both forward and inverse problems for nonlinear partial differential equations(PDEs).However,conventional DNNs are not effective in handling problems such as delay di... Deep neural networks(DNNs)are effective in solving both forward and inverse problems for nonlinear partial differential equations(PDEs).However,conventional DNNs are not effective in handling problems such as delay differential equations(DDEs)and delay integrodifferential equations(DIDEs)with constant delays,primarily due to their low regularity at delayinduced breaking points.In this paper,a DNN method that combines multi-task learning(MTL)which is proposed to solve both the forward and inverse problems of DIDEs.The core idea of this approach is to divide the original equation into multiple tasks based on the delay,using auxiliary outputs to represent the integral terms,followed by the use of MTL to seamlessly incorporate the properties at the breaking points into the loss function.Furthermore,given the increased training dificulty associated with multiple tasks and outputs,we employ a sequential training scheme to reduce training complexity and provide reference solutions for subsequent tasks.This approach significantly enhances the approximation accuracy of solving DIDEs with DNNs,as demonstrated by comparisons with traditional DNN methods.We validate the effectiveness of this method through several numerical experiments,test various parameter sharing structures in MTL and compare the testing results of these structures.Finally,this method is implemented to solve the inverse problem of nonlinear DIDE and the results show that the unknown parameters of DIDE can be discovered with sparse or noisy data. 展开更多
关键词 Delay integro-differential equation Multi-task learning parameter sharing structure deep neural network sequential training scheme
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AAV-mediated expression of p65shRNA and bone morphogenetic protein 4 synergistically enhances chondrocyte regeneration
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作者 Yu Yangyi Song Zhuoyue +2 位作者 Lian Qiang Ding Kang Li Guangheng 《中国组织工程研究》 CAS 北大核心 2025年第17期3537-3547,共11页
BACKGROUND:Adeno-associated virus(AAV)gene therapy has been proven to be reliable and safe for the treatment of osteoarthritis in recent years.However,given the complexity of osteoarthritis pathogenesis,single gene ma... BACKGROUND:Adeno-associated virus(AAV)gene therapy has been proven to be reliable and safe for the treatment of osteoarthritis in recent years.However,given the complexity of osteoarthritis pathogenesis,single gene manipulation for the treatment of osteoarthritis may not produce satisfactory results.Previous studies have shown that nuclear factorκB could promote the inflammatory pathway in osteoarthritic chondrocytes,and bone morphogenetic protein 4(BMP4)could promote cartilage regeneration.OBJECTIVE:To test whether combined application of AAV-p65shRNA and AAV-BMP4 will yield the synergistic effect on chondrocytes regeneration and osteoarthritis treatment.METHODS:Viral particles containing AAV-p65-shRNA and AAV-BMP4 were prepared.Their efficacy in inhibiting inflammation in chondrocytes and promoting chondrogenesis was assessed in vitro and in vivo by transfecting AAV-p65-shRNA or AAV-BMP4 into cells.The experiments were divided into five groups:PBS group;osteoarthritis group;AAV-BMP4 group;AAV-p65shRNA group;and BMP4-p65shRNA 1:1 group.Samples were collected at 4,12,and 24 weeks postoperatively.Tissue staining,including safranin O and Alcian blue,was applied after collecting articular tissue.Then,the optimal ratio between the two types of transfected viral particles was further investigated to improve the chondrogenic potential of mixed cells in vivo.RESULTS AND CONCLUSION:The combined application of AAV-p65shRNA and AAV-BMP4 together showed a synergistic effect on cartilage regeneration and osteoarthritis treatment.Mixed cells transfected with AAV-p65shRNA and AAV-BMP4 at a 1:1 ratio produced the most extracellular matrix synthesis(P<0.05).In vivo results also revealed that the combination of the two viruses had the highest regenerative potential for osteoarthritic cartilage(P<0.05).In the present study,we also discovered that the combined therapy had the maximum effect when the two viruses were administered in equal proportions.Decreasing either p65shRNA or BMP4 transfected cells resulted in less collagen II synthesis.This implies that inhibiting inflammation by p65shRNA and promoting regeneration by BMP4 are equally important for osteoarthritis treatment.These findings provide a new strategy for the treatment of early osteoarthritis by simultaneously inhibiting cartilage inflammation and promoting cartilage repair. 展开更多
关键词 OSTEOARTHRITIS adeno-associated virus bone morphogenetic protein 4 p65-short hairpin RNA gene therapy short hairpin RNA transforming growth factor-β1 extracellular matrix articular cartilage chondrocytes.
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Modulating NH_(2)Lewis Basicity in CTF-NH_(2)through Donor-Acceptor Groups for Optimizing Photocatalytic Water Splitting
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作者 Zhao Lu Hu Lv +1 位作者 Qinzhuang Liu Zhongliao Wang 《物理化学学报》 SCIE CAS CSCD 北大核心 2024年第12期13-14,共2页
Photocatalytic water splitting(PWS)provides an optimal approach for the sustainable production of green hydrogen.NH_(2)-modified covalent triazine frameworks(CTFs-NH_(2))hold potential in PWS due to robust light uptak... Photocatalytic water splitting(PWS)provides an optimal approach for the sustainable production of green hydrogen.NH_(2)-modified covalent triazine frameworks(CTFs-NH_(2))hold potential in PWS due to robust light uptake,optimal charge separation,and considerable redox potential.However,the high surface reaction barriers hinder the efficiency of PWS owing to the conversion difficulty of intermediate products.Modulating the Lewis basicity of NH_(2)on CTFs offers a feasible route for addressing this challenge.In this work,electron-donating ethyl(C_(2)F_(5))and electronwithdrawing 5-fluoroethyl groups(C_(2)F_(5))are introduced at the para position of amine groups,producing C_(2)F_(5)-CTF-NH_(2)and C_(2)F_(5)-CTF-NH_(2),to adjust the Lewis basicity of CTF-NH_(2).Through DFT calculations,the optical properties,excited states,electronic structures,dipole moments,and surface reaction processes of the CTF-NH_(2),C_(2)F_(5)-CTF-NH_(2)and C_(2)F_(5)-CTF-NH_(2)are simulated.The results indicate that the electron-withdrawing C_(2)F_(5)group can decrease the electron density and Lewis basicity on NH_(2),thereby lowering the energy barriers for hydrogen and oxygen evolution reactions,effectively ameliorating the PWS efficiency of CTF-NH_(2).This work unveils an innovative approach for donor-acceptor-regulated CTFs for the application of PWS. 展开更多
关键词 DONOR ACCEPTOR Water splitting CTFs Lewis basicity
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Prenatal ultrasonic characteristics and diagnosis of fetal Currarino syndrome:Report of 2 cases and review of literature
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作者 WEI Yingni ZHANG Yuchen +3 位作者 DENG Zongfeng WANG Yingqiu HUANG Qiaojie CHEN Yayan 《中国医学影像技术》 CSCD 北大核心 2024年第8期1212-1215,共4页
Objective To explore prenatal ultrasonic characteristics of fetal Currarino syndrome(CS)and methods for prenatal diagnosis of CS.Methods Two fetuses with CS confirmed by genetic examination were retrospectively analyz... Objective To explore prenatal ultrasonic characteristics of fetal Currarino syndrome(CS)and methods for prenatal diagnosis of CS.Methods Two fetuses with CS confirmed by genetic examination were retrospectively analyzed,while 6 CS fetuses with complete prenatal ultrasonic data in literature were reviewed.Prenatal ultrasonic characteristics of CS fetuses and the method for prenatal diagnosis of CS were discussed.Results Among 8 CS fetuses diagnosed with prenatal ultrasound,4 were female singletons with a clear family history of CS,and MNX 1 gene mutation was found in 1 fetus.The other 4 fetuses were 2 pairs of male monochorionic twins,all with MNX 1 gene mutation.Among 8 CS fetuses,complete triad(sacral agenesis abnormalities,anorectal malformation and presacral mass)were displayed only in 2 fetuses,while all 8 had sacral agenesis abnormalities and 6(6/8,75.00%)were detected with prenatal ultrasound,6 had low location of conus medullaris and 2(2/6,33.33%)detected with prenatal ultrasound.Conclusion Prenatal ultrasound was the first choice for non-invasive diagnosis of fetal CS.When one of sacral agenesis abnormalities,anorectal malformation and presacral mass was found with prenatal ultrasound,the possibility of CS should be considered,and fetal MRI,genetic examination and prenatal genetic counselling should be recommended if necessary. 展开更多
关键词 Currarino triad ultrasonography prenatal AMNIOCENTESIS GENES
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Perfecting HER catalysts via defects:Recent advances and perspectives
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作者 Chengguang Lang Yantong Xu Xiangdong Yao 《Chinese Journal of Catalysis》 SCIE CAS CSCD 2024年第9期4-31,共28页
Defect engineering has become a promising approach to improve the performance of hydrogen evolution reaction(HER)catalysts.Non-noble transition metal-based catalysts(TMCs)have shown significant promise as effective al... Defect engineering has become a promising approach to improve the performance of hydrogen evolution reaction(HER)catalysts.Non-noble transition metal-based catalysts(TMCs)have shown significant promise as effective alternatives to traditional platinum-group catalysts,attracting considerable attention.However,the industrial application of TMCs in electrocatalytic hydrogen production necessitates further optimization to boost both catalytic activity and stability.This review comprehensively examines the types,fabrication methods,and characterization techniques of various defects that enhance catalytic HER activity.Key advancements include optimizing defect concentration and distribution,coupling heteroatoms with vacancies,and leveraging the synergy between bond lengths and defects.In-depth discussions highlight the electronic structure and catalytic mechanisms elucidated through in-situ characterization and density functional theory calculations.Additionally,future directions are identified,exploring novel defect types,emphasizing precision synthesis methods,industrial-scale preparation techniques,and strategies to enhance structural stability and understanding the in-depth catalytic mechanism.This review aims to inspire further research and development in defect-engineered HER catalysts,providing pathways for high efficiency and cost-effectiveness in hydrogen production. 展开更多
关键词 DEFECT Hydrogen evolution reaction Catalytic mechanism Synergistic catalysis Transition metal-based catalyst
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Opto-mechanical-thermal integration analysis of Doppler asymmetric spatial heterodyne interferometer
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作者 WANG Jin-jiang JIANG Lun +3 位作者 TONG Shou-feng PEI Hui-yi CUI Yong GUO Ming-hang 《中国光学(中英文)》 EI CAS CSCD 北大核心 2024年第6期1489-1511,共23页
In order to improve the detection accuracy of Doppler asymmetric spatial heterodyne(DASH)interferometer in harsh temperatures,an opto-mechanical-thermal integration analysis is carried out.Firstly,the correlation betw... In order to improve the detection accuracy of Doppler asymmetric spatial heterodyne(DASH)interferometer in harsh temperatures,an opto-mechanical-thermal integration analysis is carried out.Firstly,the correlation between the interference phase and temperature is established according to the working principle and the phase algorithm of the interferometer.Secondly,the optical mechanical thermal analysis model and thermal deformation data acquisition model are designed.The deformation data of the interference module and the imaging optical system at different temperatures are given by temperature load simulation analysis,and the phase error caused by thermal deformation is obtained by fitting.Finally,based on the wind speed error caused by thermal deformation of each component,a reasonable temperature control scheme is proposed.The results show that the interference module occupies the main cause,the temperature must be controlled within(20±0.05)℃,and the temperature control should be carried out for the temperature sensitive parts,and the wind speed error caused by the part is 3.8 m/s.The thermal drift between the magnification of the imaging optical system and the thermal drift of the relative position between the imaging optical system and the detector should occupy the secondary cause,which should be controlled within(20±2)℃,and the wind speed error caused by the part is 3.05 m/s.In summary,the wind measurement error caused by interference module,imaging optical system,and the relative position between the imaging optical system and the detector can be controlled within 6.85 m/s.The analysis and temperature control schemes presented in this paper can provide theoretical basis for DASH interferometer engineering applications. 展开更多
关键词 Doppler asymmetric spatial heterodyne interferometer interference module imaging optical system opto-mechanical thermal integration analysis phase error temperature control
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Self-supervised learning artificial intelligence noise reduction technology based on the nearest adjacent layer in ultra-low dose CT of urinary calculi
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作者 ZHOU Cheng LIU Yang +4 位作者 QIU Yingwei HE Daijun YAN Yu LUO Min LEI Youyuan 《中国医学影像技术》 CSCD 北大核心 2024年第8期1249-1253,共5页
Objective To observe the value of self-supervised deep learning artificial intelligence(AI)noise reduction technology based on the nearest adjacent layer applicated in ultra-low dose CT(ULDCT)for urinary calculi.Metho... Objective To observe the value of self-supervised deep learning artificial intelligence(AI)noise reduction technology based on the nearest adjacent layer applicated in ultra-low dose CT(ULDCT)for urinary calculi.Methods Eighty-eight urinary calculi patients were prospectively enrolled.Low dose CT(LDCT)and ULDCT scanning were performed,and the effective dose(ED)of each scanning protocol were calculated.The patients were then randomly divided into training set(n=75)and test set(n=13),and a self-supervised deep learning AI noise reduction system based on the nearest adjacent layer constructed with ULDCT images in training set was used for reducing noise of ULDCT images in test set.In test set,the quality of ULDCT images before and after AI noise reduction were compared with LDCT images,i.e.Blind/Referenceless Image Spatial Quality Evaluator(BRISQUE)scores,image noise(SD ROI)and signal-to-noise ratio(SNR).Results The tube current,the volume CT dose index and the dose length product of abdominal ULDCT scanning protocol were all lower compared with those of LDCT scanning protocol(all P<0.05),with a decrease of ED for approximately 82.66%.For 13 patients with urinary calculi in test set,BRISQUE score showed that the quality level of ULDCT images before AI noise reduction reached 54.42%level but raised to 95.76%level of LDCT images after AI noise reduction.Both ULDCT images after AI noise reduction and LDCT images had lower SD ROI and higher SNR than ULDCT images before AI noise reduction(all adjusted P<0.05),whereas no significant difference was found between the former two(both adjusted P>0.05).Conclusion Self-supervised learning AI noise reduction technology based on the nearest adjacent layer could effectively reduce noise and improve image quality of urinary calculi ULDCT images,being conducive for clinical application of ULDCT. 展开更多
关键词 urinary calculi tomography X-ray computed artificial intelligence prospective studies
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Cu single-atom electrocatalyst on nitrogen-containing graphdiyne for CO_(2) electroreduction to CH_(4)
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作者 Hao Dai Tao Song +8 位作者 Xian Yue Shuting Wei Fuzhi Li Yanchao Xu Siyan Shu Ziang Cui Cheng Wang Jun Gu Lele Duan 《Chinese Journal of Catalysis》 SCIE CAS CSCD 2024年第9期123-132,共10页
Developing Cu single-atom catalysts(SACs)with well-defined active sites is highly desirable for producing CH4 in the electrochemical CO_(2) reduction reaction and understanding the structure-property relationship.Here... Developing Cu single-atom catalysts(SACs)with well-defined active sites is highly desirable for producing CH4 in the electrochemical CO_(2) reduction reaction and understanding the structure-property relationship.Herein,a new graphdiyne analogue with uniformly distributed N_(2)-bidentate(note that N_(2)-bidentate site=N^N-bidentate site;N_(2)≠dinitrogen gas in this work)sites are synthesized.Due to the strong interaction between Cu and the N_(2)-bidentate site,a Cu SAC with isolated undercoordinated Cu-N_(2) sites(Cu1.0/N_(2)-GDY)is obtained,with the Cu loading of 1.0 wt%.Cu1.0/N_(2)-GDY exhibits the highest Faradaic efficiency(FE)of 80.6% for CH_(4) in electrocatalytic reduction of CO_(2) at-0.96 V vs.RHE,and the partial current density of CH_(4) is 160 mA cm^(-2).The selectivity for CH_(4) is maintained above 70% when the total current density is 100 to 300 mA cm^(-2).More remarkably,the Cu1.0/N_(2)-GDY achieves a mass activity of 53.2 A/mgCu toward CH4 under-1.18 V vs.RHE.In situ electrochemical spectroscopic studies reveal that undercoordinated Cu-N_(2) sites are more favorable in generating key ^(*)COOH and ^(*)CHO intermediate than Cu nanoparticle counterparts.This work provides an effective pathway to produce SACs with undercoordinated Metal-N_(2) sites toward efficient electrocatalysis. 展开更多
关键词 Carbon dioxide reduction ELECTROCATALYSIS Cu single-atom catalyst N-containing graphdiyne Methane
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Preliminary clinical application of total free-breathing cardiac MR examination
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作者 YANG Kai YIN Gang +4 位作者 AN Jing YANG Xinling LAN Tian ZHAO Shihua LU Minjie 《中国医学影像技术》 CSCD 北大核心 2024年第8期1183-1188,共6页
Objective To observe the clinical application value of total free-breathing cardiac MR(CMR)examination preliminarily.Methods Two patients who underwent CMR scanning under free-breathing state,including cine,motion cor... Objective To observe the clinical application value of total free-breathing cardiac MR(CMR)examination preliminarily.Methods Two patients who underwent CMR scanning under free-breathing state,including cine,motion correction T1 and T2 mapping,blood flow imaging,and late gadolinium enhancement scanning were retrospectively enrolled,and the qualities of the above images were evaluated and compared with that of conventional CMR images under breath-holding state.Results No significant difference of imaging quality was found between total free-breathing and conventional breath-holding CMR.The differences of left ventricular ejection fraction,cardiac output,left ventricular end-diastolic volume index and left ventricular mass measured based on CMR images under different breath conditions were limited.Conclusion Total free-breathing CMR was feasible in clinical practice,which could provide"one-stop"evaluation of cardiac structure,function and myocardial histological characteristics,hence having promising clinical prospects. 展开更多
关键词 HEART magnetic resonance imaging respiratory motion motion correction
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Highly Sensitive Detection of Strontium Ions Using Metal-Organic Frameworks Functionalized Solid-state Nanochannels
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作者 Xu-Gang Wang Zheng-Xu He +6 位作者 De-Fang Ding Xue-Qin Luo Li Dai Wei-Qi Zhang Qun Ma Yu Huang Fan Xia 《电化学(中英文)》 CAS 北大核心 2024年第10期29-40,共12页
Strontium-90,a highly radioactive isotope,accumulates within the food chain and skeletal structure,posing significant risks to human health.There is a critical need for a sensitive detection strategy for Strontium-90 ... Strontium-90,a highly radioactive isotope,accumulates within the food chain and skeletal structure,posing significant risks to human health.There is a critical need for a sensitive detection strategy for Strontium-90 in complex environmental samples.Here,solid-state nanochannels,modified with metal-organic frameworks(MOF)and specific aptamers,were engineered for highly sensitive detection of strontium ion(Sr^(2+)).The synergistic effect between the reduced effective diameter of the nanochannels due to MOF and the specific binding of Sr^(2+) by aptamers amplifies the difference in ionic current signals,enhancing detection sensitivity significantly.The MOF-modified nanochannels exhibit highly sensitive detection of Sr^(2+),with a limit of detection(LOD)being 0.03 nmol·L^(-1),whereas the LOD for anodized aluminum oxide(AAO)without the modified MOF nanosheets is only 1000 nmol·L^(-1).These findings indicate that the LOD of Sr^(2+) detected by the MOF-modified nanochannels is approximately 33,000 times higher than that by the nanochannels without MOF modification.Additionally,the highly reliable detection of Sr^(2+) in various water samples was achieved,with a recovery rate ranging from 94.00%to 118.70%.This study provides valuable insights into the rapidly advancing field of advanced nanochannel-based sensors and their diverse applications for analyzing complex samples,including environmental contaminant detection,food analysis,medical diagnostics,and more. 展开更多
关键词 NANOCHANNEL Metal-organic frameworks Sensor Strontium ion Sensitivity detection
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Electronic structure regulation on layered double hydroxides for oxygen evolution reaction 被引量:5
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作者 Liangliang Huang Yuqin Zou +1 位作者 Dawei Chen Shuangyin Wang 《Chinese Journal of Catalysis》 SCIE EI CAS CSCD 北大核心 2019年第12期1822-1840,共19页
Oxygen evolution reactions(OERs)as core components of energy conversion and storage technology systems,such as water splitting and rechargeable metal–air batteries,have attracted considerable attention in recent year... Oxygen evolution reactions(OERs)as core components of energy conversion and storage technology systems,such as water splitting and rechargeable metal–air batteries,have attracted considerable attention in recent years.Transition metal compounds,particularly layered double hydroxides(LDHs),are considered as the most promising electrocatalysts owing to their unique two-dimensional layer structures and tunable components.However,heir poor intrinsic electrical conductivities and the limited number of active sites hinder their performances.The regulation of the electronic structure is an effective approach to improve the OER activity of LDHs,including cationic and anionic regulation,defect engineering,regulation of intercalated anions,and surface modifications.In this review,we summarize recent advances in the regulation of the electronic structures of LDHs used as electrocatalysts in OERs.In addition,we discuss the effects of each regulation type on OER activities.This review is expected to shed light on the development and design of effective OER electrocatalysts by summarizing various electronic structure regulation pathways and the effects on their catalytic performances. 展开更多
关键词 Oxygen evolution reactions Layered double hydroxide Cationic/Anionic regulation Defect engineering ELECTROCATALYST ELECTRON DOPING
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Photocatalytic performance of TiO_2 nanocrystals with/without oxygen defects 被引量:13
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作者 Shu-yuan Liu Kezhen Qi Meng Qiu 《Chinese Journal of Catalysis》 SCIE EI CAS CSCD 北大核心 2018年第4期867-875,共9页
To investigate the role of oxygen defects on the photocatalytic activity of TiO2,the TiO2 nanocrystals with/without oxygen defects are successfully synthesized by the hydrothermal and sol‐gel methods,respectively.The... To investigate the role of oxygen defects on the photocatalytic activity of TiO2,the TiO2 nanocrystals with/without oxygen defects are successfully synthesized by the hydrothermal and sol‐gel methods,respectively.The as‐prepared TiO2 nanocrystals with defects are light blue and the absorption edge of light is towards the visible light region(~420 nm).Raman and X‐ray photoelectron spectroscopy(XPS)measurements all confirm that the concentration of oxygen vacancies in the TiO2 synthesized by the sol‐gel method is less than that synthesized through the hydrothermal route.The introduction of oxygen defects contributes to a new state in the band gap that narrows the band gap,which is the reason for the extension of light absorption into the visible light region.The photocurrent results confirm that this band‐gap narrowing enhances the photocurrent response under simulated solar light irradiation.The TiO2 with oxygen defects shows a higher photocatalytic activity for decomposition of a methylene blue solution compared with that of the perfect TiO2 sample.The photocatalytic mechanism is discussed based on the density functional theory calculations and photoluminescence spectroscopy measurements. 展开更多
关键词 TIO2 DEFECT Optical property Photocatalytic activity Density functional theory calculation
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Nitrogen and sulfur dual-doped high-surface-area hollow carbon nanospheres for efficient CO2 reduction 被引量:5
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作者 Guodong Li Yongjie Qin +6 位作者 Yu Wu Lei Pei Qi Hu Hengpan Yang Qianling Zhang Jianhong Liu Chuanxin He 《Chinese Journal of Catalysis》 SCIE EI CAS CSCD 北大核心 2020年第5期830-838,共9页
The electrochemical reduction of CO2(CO2 RR) can substantially contribute to the production of useful chemicals and reduction of global CO2 emissions. Herein, we presented N and S dual-doped high-surface-area carbon m... The electrochemical reduction of CO2(CO2 RR) can substantially contribute to the production of useful chemicals and reduction of global CO2 emissions. Herein, we presented N and S dual-doped high-surface-area carbon materials(SZ-HCN) as CO2 RR catalysts. N and S were doped by one-step pyrolysis of a N-containing polymer and S powder. ZnCl2 was applied as a volatile porogen to prepare porous SZ-HCN. SZ-HCN with a high specific surface area(1510 m2 g–1) exhibited efficient electrocatalytic activity and selectivity for CO2 RR. Electrochemical measurements demonstrated that SZ-HCN showed excellent catalytic performance for CO2-to-CO reduction with a high CO Faradaic efficiency(~93%) at-0.6 V. Furthermore, SZ-HCN offered a stable current density and high CO selectivity over at least 20 h continuous operation, revealing remarkable electrocatalytic durability. The experimental results and density functional theory calculations indicated that N and S dual-doped carbon materials required lower Gibbs free energy to form the COOH* intermediate than that for single-N-doped carbon for CO2-to-CO reduction, thereby enhancing CO2 RR activity. 展开更多
关键词 High specific surface area Hollow structure Carbon-based catalysts CO2 reduction reaction Electrocatalytic selectivity
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Step-scheme ZnO@ZnS hollow microspheres for improved photocatalytic H_(2) production performance 被引量:8
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作者 Jie Jiang Guohong Wang +3 位作者 Yanchi Shao Juan Wang Shuang Zhou Yaorong Su 《Chinese Journal of Catalysis》 SCIE EI CAS CSCD 2022年第2期329-338,共10页
Constructing a step-scheme heterojunction at the interface between two semiconductors is an efficient way to optimize the redox ability and accelerate the charge carrier separation of a photocatalytic system for achie... Constructing a step-scheme heterojunction at the interface between two semiconductors is an efficient way to optimize the redox ability and accelerate the charge carrier separation of a photocatalytic system for achieving high photocatalytic performance.In this study,we prepared a hierarchical ZnO@ZnS step-scheme photocatalyst by incorporating ZnS into the outer shell of hollow ZnO microspheres via a simple in situ sulfidation strategy.The ZnO@ZnS step-scheme photocatalysts had a large surface area,high light utilization capacity,and superior separation efficiency for photogenerated charge carriers.In addition,the material simulation revealed that the formation of the step-scheme heterojunction between ZnO and ZnS was due to the presence of the built-in electric field.Our study paves the way for design of high-performance photocatalysts for H_(2) production. 展开更多
关键词 ZnO@ZnS Hollow microspheres Step-scheme heterojunction Photocatalytic H_(2)production
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Lignin valorization toward value-added chemicals and fuels via electrocatalysis:A perspective 被引量:3
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作者 Chenxin Yang Henan Chen +3 位作者 Tao Peng Baiyao Liang Yun Zhang Wei Zhao 《Chinese Journal of Catalysis》 SCIE EI CAS CSCD 2021年第11期1831-1842,共12页
Developing efficient approaches for lignin upgrading is of interest for the industrial production of chemicals and fuels from renewable biomass.Electrocatalytic lignin upgrading powered by renewable electricity operat... Developing efficient approaches for lignin upgrading is of interest for the industrial production of chemicals and fuels from renewable biomass.Electrocatalytic lignin upgrading powered by renewable electricity operating under gentle conditions(at or near ambient pressures and temperatures)enables a decentralized production of chemicals and fuels.Herein,we will cover the structures of lignin and review the recent advances in the electrocatalytic lignin upgrade,the electrocatalytic depolymerization of lignin,and the electrocatalytic upgrading of lignin monomers to value-added chemicals and fuels.Finally,we provide insights into the main challenges and future perspectives of this field. 展开更多
关键词 ELECTROCHEMISTRY ELECTROCATALYSIS LIGNIN VALORIZATION Lignin monomer
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Mechanistic studies on peroxymonosulfate activation by g-C3N4 under visible light for enhanced oxidation of light-inert dimethyl phthalate 被引量:8
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作者 Lijie Xu Lanyue Qi +4 位作者 Yang Sun Han Gong Yiliang Chen Chun Pei Lu Gan 《Chinese Journal of Catalysis》 SCIE EI CAS CSCD 北大核心 2020年第2期322-332,共11页
Excitation of metal-free graphitic carbon nitride(g-C3N4) under visible light can successfully achieve efficient activation of peroxymonosulfate(PMS). Synergistic effects and involved mechanism were systematically inv... Excitation of metal-free graphitic carbon nitride(g-C3N4) under visible light can successfully achieve efficient activation of peroxymonosulfate(PMS). Synergistic effects and involved mechanism were systematically investigated using a light-inert endocrine disrupting compound, dimethyl phthalate(DMP), as the target pollutant. Under visible light irradiation, DMP could not be degraded by direct g-C3 N4-mediated photocatalysis, while in the presence of PMS, the dominant radicals were converted from ·O2 to SO4·– and ·OH, resulting in effective DMP degradation and mineralization. Results showed that higher dosage of PMS or g-C3 N4 could increase the activation amount of PMS and corresponding DMP degradation efficiency, but the latter approach was more productive in terms of making the most of PMS. High DMP concentration hindered effective contact between PMS and g-C3 N4, but could provide efficient use of PMS. Higher DMP degradation efficiency was achieved at p H lower than the point of zero charge(5.4). Based on intermediates identification, the DMP degradation was found mainly through radical attack(·OH and SO4·–) of the benzene ring and oxidation of the aliphatic chains. 展开更多
关键词 Graphitic carbon nitride Visible light PEROXYMONOSULFATE Dimethyl phthalate ACTIVATION DEGRADATION
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Advances in magnetic flux leakage testing technology 被引量:7
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作者 ZHANG Peng WEI Minghui +1 位作者 GUO Zhiyong LIU Zhongxiang 《Journal of Measurement Science and Instrumentation》 CAS CSCD 2021年第1期1-11,共11页
Magnetic flux leakage(MFL)testing technology has the advantages of simple principle,easy engineering implementation and low requirements on the surface of the detected workpiece.Therefore,it has been one of the resear... Magnetic flux leakage(MFL)testing technology has the advantages of simple principle,easy engineering implementation and low requirements on the surface of the detected workpiece.Therefore,it has been one of the research hotspots in the field of non-destructive testing(NDT)and widely used for testing long distance pipelines.This paper presents the development of MFL tesing technology from the aspects of basic theory,influencing factors,magnetization technology,signal processing,etc.The problems to be solved and the future development are summarized,which can provide reference for the research and system development of MFL testing technology. 展开更多
关键词 non-destructive testing(NDT) magnetic flux leakage(MFL)testing magnetization and detection signal processing
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Selective CO_(2) photoreduction to CH_(4) mediated by dimension-matched 2D/2D Bi_(3)NbO_(7)/g-C_(3)N_(4) S-scheme heterojunction 被引量:7
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作者 Kai Wang Xuezhen Feng +2 位作者 Yangzi Shangguan Xiaoyong Wu Hong Chen 《Chinese Journal of Catalysis》 SCIE EI CAS CSCD 2022年第2期246-254,共9页
Discovering highly selective catalysts is key to achieve effective CO_(2) photoreduction to hydrocarbon fuels.In this work,we construct an ultrathin dimension-matched S-scheme Bi_(3)NbO_(7)/g-C_(3)N_(4) heterostructur... Discovering highly selective catalysts is key to achieve effective CO_(2) photoreduction to hydrocarbon fuels.In this work,we construct an ultrathin dimension-matched S-scheme Bi_(3)NbO_(7)/g-C_(3)N_(4) heterostructure,which permits the highly selective photocatalytic reduction of CO_(2) to CH_(4),as shown by 13C isotopic measurements.Density functional theory calculations combined with solid-state characterization confirm the electron transfer from g-C_(3)N_(4) nanosheets to Bi_(3)NbO_(7),establishing an internal electric field.The internal electric field drives photogenerated electrons from Bi_(3)NbO_(7) to g-C_(3)N_(4),as revealed by in-situ X-ray photoelectron spectroscopy,demonstrating the presence of an S-scheme charge transfer path in Bi_(3)NbO_(7)/g-C_(3)N_(4) heterostructures allowing efficient and selective CO2 photoreduction.As a result,the optimized sample achieved a CH_(4) evolution rate of 37.59μmol·g^(-1)·h^(-1),a ca.15-fold enhancement compared to ultrathin g-C_(3)N_(4) nanosheets,and also retained stability after 10 reaction cycles and 40 h of simulated solar irradiation with no sacrificial reagents.The optimized Bi3 Nb O7/g-C_(3)N_(4) composites achieve almost 90%selectivity for CH_(4) production over CO. 展开更多
关键词 Dimension-matched S-scheme Photocatalysis CO_(2)reduction Selectivity
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High activity and durability of carbon-supported core-shell PtPx@Pt/C catalyst for oxygen reduction reaction 被引量:4
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作者 Wei-Ze Li Bang-An Lu +7 位作者 Lin Gan Na Tian Peng-Yang Zhang Wei Yan Wei-Xin Chen You-Hu Chen Zhi-You Zhou Shi-Gang Sun 《Chinese Journal of Catalysis》 SCIE EI CAS CSCD 2021年第12期2173-2180,共8页
Alloying Pt with transition metals can significantly improve the catalytic properties for the oxygen reduction reaction(ORR).However,the application of Pt-transition metal alloys in fuel cells is largely limited by po... Alloying Pt with transition metals can significantly improve the catalytic properties for the oxygen reduction reaction(ORR).However,the application of Pt-transition metal alloys in fuel cells is largely limited by poor long-term durability because transition metals can easily leach.In this study,we developed a nonmetallic doping approach and prepared a P-doped Pt catalyst with excellent durability for the ORR.Carbon-supported core-shell nanoparticles with a P-doped Pt core and Pt shell(denoted as PtPx@Pt/C)were synthesized via heat-treatment phosphorization of commercial Pt/C,followed by acid etching.Compositional analysis using electron energy loss spectroscopy and X-ray photoelectron spectroscopy clearly demonstrated that Pt was enriched in the near-surface region(approximately 1 nm)of the carbon-supported core-shell nanoparticles.Owning to P doping,the ORR specific activity and mass activity of the PtP_(1.4)@Pt/C catalyst were as high as 0.62 mA cm^(–2)and 0.31 mAμgPt–^(1),respectively,at 0.90 V,and they were enhanced by 2.8 and 2.1 times,respectively,in comparison with the Pt/C catalyst.More importantly,PtP_(1.4)@Pt/C exhibited superior stability with negligible mass activity loss(6%after 30000 potential cycles and 25%after 90000 potential cycles),while Pt/C lost 46%mass activity after 30000 potential cycles.The high ORR activity and durability were mainly attributed to the core-shell nanostructure,the electronic structure effect,and the resistance of Pt nanoparticles against aggregation,which originated from the enhanced ability of the PtP_(1.4)@Pt to anchor to the carbon support.This study provides a new approach for constructing nonmetal-doped Pt-based catalysts with excellent activity and durability for the ORR. 展开更多
关键词 Oxygen reduction reaction Nonmetallic doping Phosphorization Core-shell nanostructure DURABILITY
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围术期抗焦虑治疗对术后疼痛的影响评价 被引量:11
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作者 曾武雄 《临床心身疾病杂志》 CAS 2007年第5期393-394,共2页
目的观察抗焦虑干预对术后疼痛的影响。方法将入组的78例患者随机分为观察组和对照组,每组39例。对照组手术前后给予常规处理,观察组手术前后在给予常规处理的同时,与术前1d晚上和术后6h给予口服舒乐安定2mg^4mg。两组均于手术前1d和手... 目的观察抗焦虑干预对术后疼痛的影响。方法将入组的78例患者随机分为观察组和对照组,每组39例。对照组手术前后给予常规处理,观察组手术前后在给予常规处理的同时,与术前1d晚上和术后6h给予口服舒乐安定2mg^4mg。两组均于手术前1d和手术后48h内采用焦虑自评量表评估焦虑状况,采用疼痛程度视觉模拟评分法评定疼痛程度。结果术前两组焦虑自评量表和疼痛程度视觉模拟评分无显著性差异(P>0.05);术后两组焦虑自评量表和疼痛程度视觉模拟评分,以及疼痛次数和哌替啶用量比较差异有极显著性(P<0.01)。结论围手术期抗焦虑干预可减轻患者的疼痛程度和疼痛次数,减少术后哌替定用量。 展开更多
关键词 术后疼痛 焦虑自评量表 疼痛程度用视觉模拟 疼痛干预
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