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Unsaturated bi-heterometal clusters in metal-vacancy sites of 2D MoS2 for efficient hydrogen evolution
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作者 Gonglei Shao jie xu +4 位作者 Shasha Gao Zhang Zhang Song Liu xu Zhang Zhen Zhou 《Carbon Energy》 SCIE EI CAS CSCD 2024年第3期264-275,共12页
The valence states and coordination structures of doped heterometal atoms in two-dimensional(2D)nanomaterials lack predictable regulation strategies.Hence,a robust method is proposed to form unsaturated heteroatom clu... The valence states and coordination structures of doped heterometal atoms in two-dimensional(2D)nanomaterials lack predictable regulation strategies.Hence,a robust method is proposed to form unsaturated heteroatom clusters via the metal-vacancy restraint mechanism,which can precisely regulate the bonding and valence state of heterometal atoms doped in 2D molybdenum disulfide.The unsaturated valence state of heterometal Pt and Ru cluster atoms form a spatial coordination structure with Pt–S and Ru–O–S as catalytically active sites.Among them,the strong binding energy of negatively charged suspended S and O sites for H+,as well as the weak adsorption of positively charged unsaturated heterometal atoms for H*,reduces the energy barrier of the hydrogen evolution reaction proved by theoretical calculation.Whereupon,the electrocatalytic hydrogen evolution performance is markedly improved by the ensemble effect of unsaturated heterometal atoms and highlighted with an overpotential of 84 mV and Tafel slope of 68.5 mV dec^(−1).In brief,this metal vacancy-induced valence state regulation of heterometal can manipulate the coordination structure and catalytic activity of heterometal atoms doped in the 2D atomic lattice but not limited to 2D nanomaterials. 展开更多
关键词 CLUSTERS hydrogen evolution reaction metal vacancy MOS2 unsaturated heterometal
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Analgesic Effect of Combined Spinal-Epidural Anesthesia and its Effect on TNF-α and CRP Levels in Elderly Patients with Hip Fracture During Surgical Treatment
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作者 jie xu Linyan Li Ning Wang 《Journal of Clinical and Nursing Research》 2024年第3期7-11,共5页
Objective:To observe the analgesic effect of combined spinal and epidural anesthesia on older patients undergoing hip fracture surgery.Method:One hundred and twenty elderly hip fracture surgery patients treated in our... Objective:To observe the analgesic effect of combined spinal and epidural anesthesia on older patients undergoing hip fracture surgery.Method:One hundred and twenty elderly hip fracture surgery patients treated in our hospital from January 2021 to December 2022 were selected and randomly divided into two groups,with 60 cases in the experimental group and 60 in the control group.The experimental group was given combined spinal-epidural anesthesia intervention measures,while the control group was given epidural anesthesia intervention measures.The analgesic effect,tumor necrosis factor-alpha(TNF-α),C-reactive protein(CRP)levels,and other observation indicators were analyzed after anesthesia intervention.Result:After the intervention,the analgesic effect and the evaluation results of the subjects in the experimental group were better than those in the control group(P<0.05);the obtained values of TNF-αand CRP levels in the experimental group were higher than those of the control group(P<0.05).Conclusion:The combined spinal-epidural anesthesia intervention demonstrated positive outcomes.The analgesic effect of patients during surgery and their inflammatory factor levels improved,which makes this intervention worthy of clinical application and promotion. 展开更多
关键词 Hip fracture in the elderly SURGERY Combined spinal and epidural anesthesia Analgesic effect TNF-Α CRP level
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中国尤小粪蝇属修订(双翅目:小粪蝇科)
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作者 苏立新 倪仑 +1 位作者 徐杰 王苗 《Entomotaxonomia》 CSCD 2023年第1期50-57,共8页
修订了中国尤小粪蝇属Eulimosina的种类,记述1新种:刺尤小粪蝇Eulimosina squamospina sp.nov.,并提出1新组合:瘤微小粪蝇Minilimosina(Minilimosina)prominulata(Su,2013)comb.nov.,还提供了该属分种检索表。
关键词 沼小粪蝇亚科 分类 检索表
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Sliding modes of fault activation under constant normal stiffness conditions 被引量:1
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作者 Chuanqing Zhang jie xu +3 位作者 Shengji Jin Guojian Cui Yuhang Guo Lingyu Li 《Journal of Rock Mechanics and Geotechnical Engineering》 SCIE CSCD 2023年第5期1213-1225,共13页
Fault activation has been the focus of research community for years.However,the studies of fault activation remain immature,such as the fault activation mode and its major factors under constant normal stiffness(CNS)c... Fault activation has been the focus of research community for years.However,the studies of fault activation remain immature,such as the fault activation mode and its major factors under constant normal stiffness(CNS)conditions associated with large thickness of fault surrounding rock mass.In this study,the rock friction experiments were conducted to understand the fault activation modes under the CNS conditions.Two major parameters,i.e.the initial normal stress and loading rate,were considered and calibrated in the tests.To reveal the response mechanism of fault activation,the local strains near the fault plane were recorded,and the macroscopic stresses and displacements were analyzed.The testing results show that the effect of displacement-controlled loading rate is more pronounced under the CNS conditions than that under constant normal load(CNL)conditions.Both the normal and shear stresses drop suddenly when the stick-slip occurs.The decrease and increase of the normal stress are synchronous with the shear stress in the regular stick-slip scenario,but mismatch with the shear stress during the chaotic stick-slip process.The results are helpful for understanding the fault sliding mode and the prediction and prevention of fault slip. 展开更多
关键词 Fault activation Rock friction mechanics Sliding modes Constant normal stiffness(CNS) Displacement-controlled loading rates ROCKBURST
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Temperature‑Arousing Self‑Powered Fire Warning E‑Textile Based on p-n Segment Coaxial Aerogel Fibers for Active Fire Protection in Firefighting Clothing 被引量:1
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作者 Hualing He Yi Qin +6 位作者 Zhenyu Zhu Qing Jiang Shengnan Ouyang Yuhang Wan xueru Qu jie xu Zhicai Yu 《Nano-Micro Letters》 SCIE EI CAS CSCD 2023年第12期141-160,共20页
Firefighting protective clothing is a crucial protective equipment for firefighters to minimize skin burn and ensure safety firefighting operation and rescue mission.A recent increasing concern is to develop self-powe... Firefighting protective clothing is a crucial protective equipment for firefighters to minimize skin burn and ensure safety firefighting operation and rescue mission.A recent increasing concern is to develop self-powered fire warning materials that can be incorporated into the firefighting clothing to achieve active fire protection for firefighters before the protective clothing catches fire on fireground.However,it is still a challenge to facilely design and manufacture thermoelectric(TE)textile(TET)-based fire warning electronics with dynamic surface conformability and breathability.Here,we develop an alternate coaxial wet-spinning strategy to continuously produce alternating p/n-type TE aerogel fibers involving n-type Ti_(3)C_(2)T_(x)MXene and p-type MXene/SWCNT-COOH as core materials,and tough aramid nanofiber as protective shell,which simultaneously ensure the flexibility and high-efficiency TE power generation.With such alternating p/n-type TE fibers,TET-based self-powered fire warning sensors with high mechanical stability and wearability are successfully fabricated through stitching the alternating p-n segment TE fibers into aramid fabric.The results indicate that TET-based fire warning electronics containing 50 p-n pairs produce the open-circuit voltage of 7.5 mV with a power density of 119.79 nW cm-2 at a temperature difference of 300℃.The output voltage signal is then calculated as corresponding surface temperature of firefighting clothing based on a linear relationship between TE voltage and temperature.The fire alarm response time and flame-retardant properties are further displayed.Such self-powered fire warning electronics are true textiles that offer breathability and compatibility with body movement,demonstrating their potential application in firefighting clothing. 展开更多
关键词 Self-powered fire warning Coaxial wet spinning P-n segment thermoelectric fiber Thermoelectric textiles Active fire protection
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Enhanced microwave absorption property of silver decorated biomass ordered porous carbon composite materials with frequency selective surface incorporation 被引量:1
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作者 Yi Liu Jingnan Qin +2 位作者 Linlin Lu jie xu Xiaolei Su 《International Journal of Minerals,Metallurgy and Materials》 SCIE EI CAS CSCD 2023年第3期525-535,共11页
Porous carbon(PC)is a promising electromagnetic(EM)wave absorbing material thanks to its light weight,large specific surface area as well as good dissipating capacity.To further improve its microwave absorbing perform... Porous carbon(PC)is a promising electromagnetic(EM)wave absorbing material thanks to its light weight,large specific surface area as well as good dissipating capacity.To further improve its microwave absorbing performance,silver coated porous carbon(Ag@PC)is synthesized by one-step hydro-thermal synthesis process making use of fir as a biomass formwork.Phase compositions,morphological structure,and microwave absorption capability of the Ag@PC has been explored.Research results show that the metallic Ag was successfully reduced and the particles are evenly distributed inward the pores of the carbon formwork,which accelerates graphitization process of the amorphous carbon.The Ag@PC composite without adding polyvinyl pyrrolidone(PVP)exhibits higher dielectric constant and better EM wave dissipating capability.This is because the larger particles of Ag give rise to higher electric conductivity.After combing with frequency selective surface(FSS),the EM wave absorbing performance is further improved and the frequency region below-10 d B is located in8.20-11.75 GHz,and the minimal reflection loss value is-22.5 dB.This work indicates that incorporating metallic Ag particles and FSS provides a valid way to strengthen EM wave absorbing capacity of PC material. 展开更多
关键词 biomass carbon Ag@PC composite material frequency selective surface electromagnetic wave absorbing property
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A Federated Named Entity Recognition Model with Explicit Relation for Power Grid 被引量:1
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作者 Jingtang Luo Shiying Yao +2 位作者 Changming Zhao jie xu Jim Feng 《Computers, Materials & Continua》 SCIE EI 2023年第5期4207-4216,共10页
The power grid operation process is complex,and many operation process data involve national security,business secrets,and user privacy.Meanwhile,labeled datasets may exist in many different operation platforms,but th... The power grid operation process is complex,and many operation process data involve national security,business secrets,and user privacy.Meanwhile,labeled datasets may exist in many different operation platforms,but they cannot be directly shared since power grid data is highly privacysensitive.How to use these multi-source heterogeneous data as much as possible to build a power grid knowledge map under the premise of protecting privacy security has become an urgent problem in developing smart grid.Therefore,this paper proposes federated learning named entity recognition method for the power grid field,aiming to solve the problem of building a named entity recognition model covering the entire power grid process training by data with different security requirements.We decompose the named entity recognition(NER)model FLAT(Chinese NER Using Flat-Lattice Transformer)in each platform into a global part and a local part.The local part is used to capture the characteristics of the local data in each platform and is updated using locally labeled data.The global part is learned across different operation platforms to capture the shared NER knowledge.Its local gradients fromdifferent platforms are aggregated to update the global model,which is further delivered to each platform to update their global part.Experiments on two publicly available Chinese datasets and one power grid dataset validate the effectiveness of our method. 展开更多
关键词 Power grid named entity recognition federal learning
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Theoretical analysis of surface waves in piezoelectric medium with periodic shunting circuits
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作者 Youqi ZHANG Rongyu XIA +2 位作者 jie xu Kefu HUANG Zheng LI 《Applied Mathematics and Mechanics(English Edition)》 SCIE EI CSCD 2023年第8期1287-1304,共18页
The investigations of surface waves in the piezoelectric medium bring out great possibility in designing smart surface acoustic wave(SAW)devices.It is important to study the dispersion properties and manipulation mech... The investigations of surface waves in the piezoelectric medium bring out great possibility in designing smart surface acoustic wave(SAW)devices.It is important to study the dispersion properties and manipulation mechanism of surface waves in the semi-infinite piezoelectric medium connected with periodic arrangement of shunting circuits.In this study,the extended Stroh formalism is developed to theoretically analyze the dispersion relations of surface waves under different external circuits.The band structures of both the Rayleigh wave and the Bleustein-Gulyaev(BG)wave can be determined and manipulated with proper electrical boundary conditions.Furthermore,the electromechanical coupling effects on the band structures of surface waves are discussed to figure out the manipulation mechanism of adjusting electric circuit.The results indicate that the proposed method can explain the propagation behaviors of surface waves under the periodic electrical boundary conditions,and can provide an important theoretical guidance for designing novel SAW devices and exploring extensive applications in practice. 展开更多
关键词 METAMATERIAL phononic crystal surface wave PIEZOELECTRICITY electromechanical coupling Stroh formalism
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Retrieval and Regional Distribution Analysis of Ammonia,Sulfur Dioxide and Nitrogen Dioxide in the Urban Environment Using Ultraviolet DOAS Algorithm
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作者 Hao Chen jie xu +5 位作者 YiboHu Fuzhou Niu Zhiyan Li Dan Wang Guizhong Fu Chuanxin Li 《Computer Modeling in Engineering & Sciences》 SCIE EI 2023年第2期1251-1262,共12页
Aiming at the in situ and mobile observation of urban environmental air pollution,a portable instrument using ultraviolet spectrum retrieval algorithm was developed based on the basis of Differential Optical Absorptio... Aiming at the in situ and mobile observation of urban environmental air pollution,a portable instrument using ultraviolet spectrum retrieval algorithm was developed based on the basis of Differential Optical Absorption Spectroscopy(DOAS)and multiple-pass cell technique.Typical trace gas pollutants,NH3,SO2,and NO2,were explored using their optical spectral characteristics in deep ultraviolet wavelength range from 210 to 215 nm.The gas concentration was retrieved by Lambert-Beer’s law and nonlinear least square method.With an optimized optical alignment,the detection limits of NH3,SO2,NO2 were estimated to be 2.2,2.3,and 36.2 ppb,respectively.The system was used in carrying out some cruise observations in Chengdu,China.During the entire period,the polluted gases showed varied distribution and typical daily average concentrations ofNH3,SO2,NO2 were 23.2,3.5,and 106.0 ppb,respectively.The contributions from different sources were analyzed combined with the HYSPLIT model.Results show that the portable DOAS system is a convenient and effective tool for regional distribution measurement and pollution source monitoring. 展开更多
关键词 Ultraviolet DOAS algorithm retrieve method white cell urban environment regional distribution
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Integrated Sensing and Communication for Future Wireless Networks
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作者 Shi Jin Christos Masouros +2 位作者 Fan Liu jie xu jie Yang 《China Communications》 SCIE CSCD 2023年第9期I0002-I0005,共4页
Integrated sensing and communication(ISAC)is anticipated to play a pivotal role in realizing the ability to sense,control,and optimize wireless environments,as well as providing ubiquitous connectivity with ultra-high... Integrated sensing and communication(ISAC)is anticipated to play a pivotal role in realizing the ability to sense,control,and optimize wireless environments,as well as providing ubiquitous connectivity with ultra-high throughput and reliability,and ultra-low latency for future wireless networks.Therefore,it can meet the requirements of mass data transmission,centimeter-level localization,and highly fine-grained environmental sensing for new applications,such as extended reality,holographic communication,autonomous driving,smart healthcare,and intelligent industry.The technology of ISAC deviates from traditional pattern of isolated design for communication and sensing.It can efficiently utilize wireless resources and potentially achieve mutual benefits by combining sensing and communication systems.The ultimate goal of the ISAC system has two aspects.On the one hand,the wireless communication system gains new functions。 展开更多
关键词 utilize mutual HOLOGRAPHIC
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Concise Strategies to Enhance the High-Rate Performance of Li_(3)VO_(4) Anodes:Cl Doping,Carbon Coating,and Spherical Architecture Design
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作者 Zongping Zhang jie xu +5 位作者 Dongmei Zhang Huijuan Ma Tao Li Ting Xiao Cunyuan Pei Shibing Ni 《Transactions of Tianjin University》 EI CAS 2023年第2期110-119,共10页
The safe operating voltage and low volume variation of Li_(3)VO_(4)(LVO)make it an ideal anode material for lithium(Li)-ion batteries.However,the insufficient understanding of the inner storage mechanism hinders the d... The safe operating voltage and low volume variation of Li_(3)VO_(4)(LVO)make it an ideal anode material for lithium(Li)-ion batteries.However,the insufficient understanding of the inner storage mechanism hinders the design of LVO-based electrodes.Herein,we investigate,for the first time,the Li-ion storage activity in LVO via Cl doping.Moreover,N-doped C coating was simultaneously achieved in the Cl doping process,resulting in synergistically improved reaction kinetics.As a result,the as-prepared Cl-doped Li_(3)VO_(4) coated with N-doped C(Cl-LVO@NC)electrodes deliver a discharge capacity of 884.1 mAh/g after 200 cycles at 0.2 A/g,which is the highest among all of the LVO-based electrodes.The Cl-LVO@NC electrodes also exhibit high-capacity retention of 331.1 mAh/g at 8.0 A/g and full capacity recovery after 5 periods of rate testing over 400 cycles.After 5000 cycles at 4.0 A/g,the discharge capacity can be maintained at 423.2 mAh/g,which is superior to most LVO-based electrodes.The Li-ion storage activity in LVO via Cl doping and significant improvement in the high-rate Li-ion storage reported in this work can be used as references for the design of advanced LVO-based electrodes for high-power applications. 展开更多
关键词 Li_(3)VO_(4) Cl doping New mechanisms High-rate Li-ion storage
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A Novel Dominant Allele from 93-11, ES(4), Represses Reactive Oxygen Species Scavenging and Leads to Early-Senescence in Rice
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作者 Zhishu Jiang Cong Gan +5 位作者 Yulian Liu Xiaoli Lin Limei Peng Yongping Song Xiaowei Luo jie xu 《Phyton-International Journal of Experimental Botany》 SCIE 2023年第3期665-677,共13页
Senescence is the last developmental process in plant,which has an important impact on crop yield and quality.In this study,a stable hereditary early-senescence line BC64 was isolated from the high-generation recombin... Senescence is the last developmental process in plant,which has an important impact on crop yield and quality.In this study,a stable hereditary early-senescence line BC64 was isolated from the high-generation recombinant inbred lines of 93-11 and Wuyunjing7(W7).Genetic analysis showed that the premature aging phenotype was controlled by a dominant gene derived from 93-11.By linkage analysis,the gene was primarily mapped in the region between marker B4 and B5 near the centromere of chromosome 4,described as ES(4).Through multiple backcrossing with W7,the near-isogenic line of ES(4)(NIL-ES(4))was obtained.Compared with wild-type W7,NIL-ES(4)plants showed more sever senescence phenotype in both nature and dark conditions.In NIL plants,leaves turned yellow at the fully tillering stage;photosynthetic rate,pollen fertility and seed setting rate were decreased.Moreover,the malondialdehyde,proline content and relative conductivity in NIL-ES(4)were significantly higher than those in W7;both transcript level and activities of reactive oxygen species scavenging enzymes were repressed;H2O2 and O^(2−)were significantly accumulated.This study provides a basis for further cloning and function identification of ES(4). 展开更多
关键词 RICE early-senescence gene mapping chlorophyll degradation reactive oxygen species scavenging
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Using machine learning to identify factors related to nitrous oxide(laughing gas)relapse among adolescents
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作者 jie xu Yi Zhang +3 位作者 Chang Lei Pei Sun Runsen Chen Tifei Yuan 《General Psychiatry》 CSCD 2023年第2期138-142,共5页
Introduction Nitrous oxide(N2O/laughing gas)has been used in medical practice as an inhalational anaesthetic and analgesic for more than 150 years.1 In the past decades,N2O exhibited increasing popularity among recrea... Introduction Nitrous oxide(N2O/laughing gas)has been used in medical practice as an inhalational anaesthetic and analgesic for more than 150 years.1 In the past decades,N2O exhibited increasing popularity among recreational drug users for its euphoric effects,potentially through its interaction with the endogenous opioid system.2 Recreational use of N2O emerged as the seventh most used drug globally in the past decade.3 The use of N2O can cause myelopathy,myocardial injury,anaemia,severe mood disorders,sensory and motor neuropathy,and psychotic symptoms.45 Prolonged N2O intake results in vitamin B12 deficiency and inhibits methionine synthetase,folate and DNA production,leading to plasma homocysteine(HCY)level elevation and bone marrow haematopoietic dysfunction.6 This study aimed to investigate the neurological symptoms of nitrous oxide use and then explore the relapse trajectory and risk factors for relapse. 展开更多
关键词 RELAPSE VITAMIN ENDOGENOUS
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Analysis of clinical characteristics and risk factors between elderly patients with severe and nonsevere Omicron variant infection
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作者 Xiao-Qin Liu Guan-Zhu Lu +4 位作者 Dong-Lin Yin Yao-Yue Kang Yuan-Yuan Zhou Yu-Huan Wang jie xu 《World Journal of Clinical Infectious Diseases》 2023年第4期37-48,共12页
BACKGROUND Coronavirus disease 2019(COVID-19),caused by severe acute respiratory syndrome coronavirus 2(SARS-CoV-2),has led to millions of confirmed cases and deaths worldwide.Elderly patients are at high risk of deve... BACKGROUND Coronavirus disease 2019(COVID-19),caused by severe acute respiratory syndrome coronavirus 2(SARS-CoV-2),has led to millions of confirmed cases and deaths worldwide.Elderly patients are at high risk of developing and dying from COVID-19 due to advanced age,decreased immune function,intense inflammatory response,and comorbidities.Shanghai has experienced a wave of infection with Omicron,a new variant of SARS-CoV-2,since March 2022.There is a pressing need to identify clinical features and risk factors for disease progression among elderly patients with Omicron infection to provide solid evidence for clinical policy-makers,public health officials,researchers,and the general public.AIM To investigate clinical characteristic differences and risk factors between elderly patients with severe and nonsevere Omicron SARS-CoV-2 variant infection.METHODS A total of 328 elderly patients with COVID-19 admitted to the Ninth People’s Hospital Affiliated to Shanghai Jiao Tong University School of Medicine from April 2022 to June 2022 were enrolled and divided into a severe group(82 patients)and a nonsevere group(246 patients)according to the diagnosis and treatment protocol of COVID-19(version 7).The clinical data and laboratory results of both groups were collected and compared.A chi-square test,t test,Mann-Whitney U test,hierarchical log-rank test,univariate and multivariate logistic regression,and hierarchical analyses were used to determine significant differences.RESULTS The severe group was older(84 vs 74 years,P<0.001),included more males(57.3%vs 43.9%,P=0.037),had a lower vaccination rate(P<0.001),and had a higher proportion of comorbidities,including chronic respiratory disease(P=0.001),cerebral infarction(P<0.001),chronic kidney disease(P=0.002),and neurodegenerative disease(P<0.001),than the nonsevere group.In addition,severe disease patients had a higher inflammatory index(P<0.001),greater need for symptomatic treatment(P<0.001),longer hospital stay(P=0.011),extended viral shedding time(P=0.014),and higher mortality than nonsevere disease patients(P<0.001).No difference was observed in the application of Paxlovid in the severe and nonsevere groups(P=0.817).Oxygen saturation,cerebral infarction,and D-dimer were predictive factors for developing severe disease in patients with COVID-19,with D-dimer having an excellent role(area under the curve:90.1%,95%CI:86.1-94.0%).In addition,D-dimer was a risk factor for developing severe COVID-19 according to multivariate stratified analysis.CONCLUSION The clinical course of severe COVID-19 is complex,with a higher need for symptomatic treatment.D-dimer is a suitable biomarker for identifying patients at risk for developing severe COVID-19. 展开更多
关键词 Coronavirus disease 2019 Omicron Severe infection Elderly patients Clinical features Risk factor
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新生儿眼底病变筛查及视网膜出血的影响因素 被引量:20
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作者 陈艳丽 徐洁 +1 位作者 纪淑兴 唐文 《国际眼科杂志》 CAS 北大核心 2019年第2期326-328,共3页
目的:筛查统计新生儿眼底病变的基本情况,并探讨新生儿视网膜出血的影响因素。方法:收集2016-01-01/2018-05-31于我院产科病房及新生儿重症监护病房采用儿童数字化广域成像系统(RetcamⅢ)进行眼底筛查的新生儿,记录其性别、胎龄、分娩... 目的:筛查统计新生儿眼底病变的基本情况,并探讨新生儿视网膜出血的影响因素。方法:收集2016-01-01/2018-05-31于我院产科病房及新生儿重症监护病房采用儿童数字化广域成像系统(RetcamⅢ)进行眼底筛查的新生儿,记录其性别、胎龄、分娩方式、窒息史、母孕史等临床资料,并对筛查结果进行统计分析。结果:本研究纳入新生儿289例,其中早产儿97例,足月儿192例。检出眼底病变者64例(22. 1%),其中视网膜出血者34例(11. 8%)、早产儿视网膜病变者23例(8. 0%)。单因素分析发现,胎龄、分娩方式、经阴产情况、有无窒息史、有无母孕期妊高征史、分娩史是新生儿视网膜出血的影响因素。多因素Logistic回归分析显示,早产儿、经阴道分娩、有窒息史、母孕期妊高征史是新生儿视网膜出血的高危因素。结论:新生儿视网膜出血发生率较高,其与胎龄、分娩方式、窒息史、母孕期妊高征史等多种因素相关,临床诊疗中应高度重视新生儿眼底病变的筛查。 展开更多
关键词 视网膜出血 新生儿眼底筛查 危险因素 儿童数字化广域成像系统
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不确定因素下薄壁铝合金管弯曲的多目标连续稳健优化设计(英文) 被引量:6
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作者 李恒 许杰 +2 位作者 杨恒 杨合 李光俊 《Transactions of Nonferrous Metals Society of China》 SCIE EI CAS CSCD 2017年第3期608-615,共8页
结合实验设计和三维弹塑性有限元,在确定性优化设计基础上,提出了不确定因素下薄壁铝合金管数控弯曲的多目标连续稳健优化方法。基于部分析因设计,获得了显著的噪声因子,包括管材性能变化、管材几何尺寸波动和管材-模具摩擦波动。采用... 结合实验设计和三维弹塑性有限元,在确定性优化设计基础上,提出了不确定因素下薄壁铝合金管数控弯曲的多目标连续稳健优化方法。基于部分析因设计,获得了显著的噪声因子,包括管材性能变化、管材几何尺寸波动和管材-模具摩擦波动。采用田口内外表试验法,考虑主要弯曲成形缺陷,对薄壁铝管数控弯曲芯模直径、芯棒伸出量和助推速度进行了稳健优化设计。通过分别考虑摩擦接触条件、管材料参数和管材几何参数的波动,实现了薄壁铝管数控弯曲芯模直径的稳健性优化设计;通过考虑材料参数波动、芯模与管间的摩擦波动以及芯模直径的制造偏差,实现了芯棒伸出量和助推速度的稳健性优化设计。 展开更多
关键词 稳健优化 管材弯曲 不确定因素 铝合金 多目标优化
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简便方法合成含铁石墨相氮化碳材料及其催化苯直接羟基化制苯酚(英文) 被引量:5
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作者 薛冰 陈晔 +3 位作者 洪颖 马丁阳 许杰 李永昕 《Chinese Journal of Catalysis》 SCIE EI CAS CSCD 北大核心 2018年第7期1263-1271,共9页
苯酚是一种重要的基本有机化工原料.全球近90%的苯酚都是经"三步异丙苯法"工艺合成而得,但是该工艺存在单程苯酚收率低(<5%)、酸污染严重等不足.同时由于联产丙酮,苯酚的产量也受丙酮市场所制约.由苯经氧化或羟基化一步法... 苯酚是一种重要的基本有机化工原料.全球近90%的苯酚都是经"三步异丙苯法"工艺合成而得,但是该工艺存在单程苯酚收率低(<5%)、酸污染严重等不足.同时由于联产丙酮,苯酚的产量也受丙酮市场所制约.由苯经氧化或羟基化一步法合成苯酚是催化化学领域中一项极具挑战的课题.由于苯分子较难活化,而苯酚易于深度氧化,因此研发和设计具有高活性和高选择性的催化剂是该课题的研究核心.因具有诸多特殊的理化性质,石墨相氮化碳(g-C_3N_4)作为一种新型碳质材料近年来在光催化、热催化、燃料电池和气体吸附等领域展示出广阔的应用前景.g-C_3N_4的类石墨层基本单元为大π共轭的三均三嗪环,对苯分子具有良好的吸附和活化能力.目前,g-C_3N_4(尤其是具有高比表面的介孔材料)在苯Friedel-Crafts烷基化和酰基化反应、苯的CO2氧化等反应中均显示了良好的催化活性.尽管如此,由于缺乏合适的氧化活性中心,纯的g-C_3N_4对苯直接羟基化几乎无催化活性.本课题组曾将乙酰丙酮氧钒和氧化钒负载至介孔g-C_3N_4,发现该类催化剂在H2O2参与的苯直接羟基化反应中,苯转化率高达18%,而苯酚选择性大于95%.然而,此类介孔g-C_3N_4均采用硬模板法合成,制备周期长且需要HF溶液蚀刻氧化硅模板.另外,钒基组分在介孔g-C_3N_4表面也存在着部分溶脱现象.本文以FeCl_3和二氰二胺为前驱体,通过一步热解法直接合成了含铁的g-C_3N_4材料(Fe-g-C_3N_4).采用N2吸附-脱附、XRD、TG、FT-IR、UV-vis、XPS光谱和TEM对材料的理化性质进行表征.结果显示,Fe的原位引入能显著提高g-C_3N_4的比表面积和孔体积,且使其依然保持石墨相结构.同时,富N的g-C_3N_4材料能有效地锚定Fe离子,使其均匀地分散在载体表面.作为多相催化剂,Fe-g-C_3N_4在H_2O_2环境下对苯羟基化合成苯酚的反应表现出较高的催化活性.当反应温度为60°C,其苯酚收率最高可达17.5%,且回收使用多次催化剂活性表现稳定.与之前报道的含铁和负载氧化钒或乙酰丙酮氧钒的g-C_3N_4催化剂材料相比,Fe-g-C_3N_4催化剂制备工艺更加简便. 展开更多
关键词 羟基化 石墨相氮化碳 苯酚
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骨来源恶性肿瘤临床疗效的评估 被引量:2
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作者 谢璐 许婕 +4 位作者 李原 刘蓉 孙昆昆 沈丹华 郭卫 《中国肿瘤临床》 CAS CSCD 北大核心 2019年第4期184-189,共6页
目的:通过现有实体瘤临床评估体系,对骨来源恶性肿瘤术前化疗前后的影像学资料进行总结,对比病理学评估结果,进一步提出并完善适合骨来源恶性肿瘤疗效的临床评估体系。方法:回顾性分析自2014年6月至2017年3月就诊于北京大学人民医院的19... 目的:通过现有实体瘤临床评估体系,对骨来源恶性肿瘤术前化疗前后的影像学资料进行总结,对比病理学评估结果,进一步提出并完善适合骨来源恶性肿瘤疗效的临床评估体系。方法:回顾性分析自2014年6月至2017年3月就诊于北京大学人民医院的190例连续病例,最后纳入研究157例,通过病理学Huvos分级将病例进行分组,对术前化疗前后的临床资料(肿瘤最大径变化、代谢参数的变化,以及一些公认的描述性参数)进行差异性检验及通过受试者工作曲线(receiver operating characteristic curve,ROC)计算肿瘤各项参数的变化率对术前化疗病理反应的ROC曲线下面积,并判断病理学分级的截点。结果:对原发肢体骨包含软组织包块的病例,判断坏死率为100%、90%及50%的最大径变化率截点分别为86%、50.7%和0.02%,骨扫描的T/B值变化率对坏死率预测效果不好,而PET/CT的SUVmax变化率对应坏死率为90%和50%的截点分别为60.7%和31.4%;而骨性边界变清晰及骨性密度增高为90%以上的病理学特异性表现形式。对不含软组织包块的原发纯骨内病变的病例,尚未发现有意义的临床评估指标。对中轴骨(包括颌面骨、脊柱及骨盆等)的病灶,由于病例数少,临床评估的截点目前区分度不大。结论:本研究对骨来源肿瘤的疗效临床评估提出了更具体的定义和不同病理学分级的界值,该临床评估体系的完善需通过前瞻、多中心、大宗数据进一步验证和讨论。 展开更多
关键词 骨肉瘤 尤文肉瘤 临床评估 病理学评估 化疗 靶向治疗
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Passengers gathering-scattering analysis at the corners of subway stations
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作者 jie xu Yihan Shi Hui Zhang 《Digital Transportation and Safety》 2023年第2期139-149,共11页
During both daily operation and emergency evacuation,the corners of walking facilities in subway stations play an important role in efficient circulation.However,the effectiveness of the corner is difficult to assess.... During both daily operation and emergency evacuation,the corners of walking facilities in subway stations play an important role in efficient circulation.However,the effectiveness of the corner is difficult to assess.In this paper,a method of passenger gathering and scattering analysis based on queueing models was proposed to investigate the corner performance in subway stations.Firstly,we constructed a set of state spaces of passenger flow according to passenger density and proposed the state transition model of passenger flow.Moreover,the model of passenger flow blocking and unblocking probability were also presented.Then,to illustrate the validity of the method and model,several passenger gathering-scattering scenarios and were simulated to verify the influence of passenger distribution and facility width on passenger walking,and the blocking probability,throughput,and expected time were also analyzed under various widths of the target corridor and arrival rates.Results showed that the proposed model can reproduce the trend of walking parameters changing and the self-organizing phenomenon of'faster is lower'.With the increase of arrival rates of passengers,walking speeds of passengers decrease and the expected walking time is prolonged,and the blocking probability sharply increased when the arrival rate exceeded 7 peds/s.In addition,with change of width of the target facility,efficiency of capacity of walking circulation facility fluctuated.With the width of the target corridor enlarged by 10%,the steady state of passenger flow was less crowded.Therefore,corridor width is critical to the circulation efficiency of passengers in subway stations.The conclusions will help to develop reasonable passenger flow control plans to ease the jam and keep passengers walking safely. 展开更多
关键词 Subway station CORNER Gathering-scattering behavior Queueing model Transition probability model
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输尿管镜下输尿管长段撕脱的处理和思考 被引量:1
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作者 徐杰 严威 +1 位作者 高文喜 周洁 《中国内镜杂志》 2021年第10期78-81,共4页
目的探讨输尿管镜手术致输尿管长段撕脱的处理方法。方法对3例输尿管长段分别为18、20和21 cm撕脱患者进行诊治,1例行膀胱瓣管残端吻合术,1例行膀胱瓣管肾盂吻合术,1例行回肠代输尿管术,均于腔内放置双J管。结果行膀胱瓣管输尿管残端吻... 目的探讨输尿管镜手术致输尿管长段撕脱的处理方法。方法对3例输尿管长段分别为18、20和21 cm撕脱患者进行诊治,1例行膀胱瓣管残端吻合术,1例行膀胱瓣管肾盂吻合术,1例行回肠代输尿管术,均于腔内放置双J管。结果行膀胱瓣管输尿管残端吻合术的患者于术后7个月取出双J管,1个月后复查无肾积水,无其他并发症,恢复良好。行膀胱瓣管肾盂吻合术的患者,术后3个月取出双J管,1个月后复查,出现吻合口旁边囊肿,后期行自体肾移植术。行回肠代输尿管术的患者,于术后6个月取出双J管,1个月后复查无肾积水,恢复良好。结论输尿管镜下输尿管长段撕脱需及时行膀胱瓣管代输尿管术、回肠代输尿管术或自体肾移植术,需在术后6个月以后考虑取出双J管,使输尿管损伤得到最佳处理效果。 展开更多
关键词 输尿管 长段损伤 处理 思考 输尿管镜下
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