检索结果-南通市图书馆

Development of an automatic measurement system using atmospheric pressure photoionization ultrahigh-resolution mass spectrometry and application for on-line analysis of particulate matter

在线全文

学校读者我要写书评

暂无评论

Journal of Environmental Sciences 2024年第4期138卷 516-530页

作者： Yayuan Dong Ranran liu Ling Xie Xiaole pan Yele Sun Lin Wu ZifaWang State Key Laboratory of Atmospheric Boundary Layer Physics and Atmospheric Chemistry Institute of Atmospheric PhysicsChinese Academy of SciencesBeijing 100029China College of Earth and Planetary Sciences University of Chinese Academy of SciencesBeijing 100049China Center for Excellence in Regional Atmospheric Environment Chinese Academy of SciencesInstitute of Urban EnvironmentXiamen 361021China

On-line chemical characterization of atmospheric particulate matter(PM)with soft ionization technique and ultrahigh-resolution Mass Spectrometry(UHRMS)provides molecular information of organic constituents in real time.Here we describe the development and application of an automatic measurement system that incorporates PM_(2.5)sampling,thermal desorption,atmospheric pressure photoionization,and UHRMS analysis.Molecular formulas of detected organic compounds were deducted from the accurate(±10 ppm)molecular weights obtained at a mass resolution of 100,000,allowing the identification of small organic compounds in PM_(2.5).Detection efficiencies of 28 standard compounds were determined and we found a high sensitivity and selectivity towards organic amines with limits of detection below 10 pg.As a proof of principle,PM_(2.5)samples collected off-line in winter in the urban area of Beijing were analyzed using the Ionization Module and HRMS of the system.The automatic system was then applied to conduct on-line measurements during the summer time at a time resolution of 2 hr.The detected organic compounds comprised mainly CHON and CHN compounds below 350 m/z.Pronounced seasonal variations in elemental composition were observed with shorter carbon backbones and higher O/C ratios in summer than that in winter.This result is consistent with stronger photochemical reactions and thus a higher oxidation state of organics in summer.Diurnal variation in signal intensity of each formula provides crucial information to reveal its source and formation pathway.In summary,the automatic measurement system serves as an important tool for the on-line characterization and identification of organic species in PM_(2.5).

关键词： PM_(2.5) Chemical composition On-line measurement technique High resolution mass spectrometry

Scenario Modeling-Aided AP Placement Optimization Method for Indoor Localization and Network Access

在线全文

学校读者我要写书评

暂无评论

China Communications 2024年第3期21卷 37-50页

作者： pan Hao Chen Yu Qi Xiaogang liu Meili School of Mathematics and Statistics Xidian UniversityXi’an 710126China Science and Technology on Near-Surface Detection Laboratory Wuxi 214035China School of Software Nanchang Hangkong UniversityNanchang 330063China

Owing to the ubiquity of wireless networks and the popularity of WiFi infrastructures,received signal strength(RSS)-based indoor localization systems have received much attention.The placement of access points(APs)significantly influences localization accuracy and network access.However,the indoor scenario and network access are not fully considered in previous AP placement optimization methods.This study proposes a practical scenario modelingaided AP placement optimization method for improving localization accuracy and network access.In order to reduce the gap between simulation-based and field measurement-based AP placement optimization methods,we introduce an indoor scenario modeling and Gaussian process-based RSS prediction method.After that,the localization and network access metrics are implemented in the multiple objective particle swarm optimization(MOPSO)solution,Pareto front criterion and virtual repulsion force are applied to determine the optimal AP placement.Finally,field experiments demonstrate the effectiveness of the proposed indoor scenario modeling method and RSS prediction model.A thorough comparison confirms the localization and network access improvement attributed to the proposed anchor placement method.

关键词： indoor localization MOPSO network access RSS prediction

A UWB/IMU-Assisted Fingerprinting Localization Framework with Low Human Efforts

在线全文

学校读者我要写书评

暂无评论

China Communications 2024年第6期21卷 40-52页

With the rapid development of smart phone,the location-based services(LBS)have received great attention in the past decades.Owing to the widespread use of WiFi and Bluetooth devices,Received Signal Strength Indication(RSSI)fingerprintbased localization method has obtained much development in both academia and industries.In this work,we introduce an efficient way to reduce the labor-intensive site survey process,which uses an UWB/IMU-assisted fingerprint construction(UAFC)and localization framework based on the principle of Automatic radio map generation scheme(ARMGS)is proposed to replace the traditional manual measurement.To be specific,UWB devices are employed to estimate the coordinates when the collector is moved in a reference point(RP).An anchor self-localization method is investigated to further reduce manual measurement work in a wide and complex environment,which is also a grueling,time-consuming process that is lead to artificial errors.Moreover,the measurements of IMU are incorporated into the UWB localization algorithm and improve the label accuracy in fingerprint.In addition,the weighted k-nearest neighbor(WKNN)algorithm is applied to online localization phase.Finally,filed experiments are carried out and the results confirm the effectiveness of the proposed approach.

关键词： indoor localization machine learning ultra wideband WiFi fingerprint

Relationship between hydrogenation degree and pyrolysis performance of jet fuel

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Chemical Engineering 2024年第4期68卷 35-42页

作者： Qing liu Tinghao Jia Lun pan Jijun Zou Xiangwen Zhang Key Laboratory for Green Chemical and Technology School of Chemical Engineering and TechnologyTianjin UniversityTianjin 300072China Haihe Laboratory of Sustainable Chemical Transformations Tianjin 300192China Zhejiang Institute of Tianjin University Ningbo 315201China Zhejiang Provincial Key Laboratory of Advanced Chemical Engineering Manufacture Technology College of Chemical and Biological EngineeringZhejiang UniversityHangzhou 310027China

Understanding the relationship between the chemical composition and pyrolysis performance of endothermic hydrocarbon fuel(EHF)is of great significance for the design and optimization of advanced EHFs.In this work,the effect of deep hydrogenation on the pyrolysis of commercial RP-3 is investigated.Fuels with different hydrogenation degrees were obtained by the partially and completely catalytic hydrogenation and their pyrolysis performances were investigated using an apparatus equipped with an electrically heated tubular reactor.The results show that with the increase of hydrogenation degree,fuel conversion almost remains constant during the pyrolysis process(500e650C,4 MPa);however,the heat sink increases slightly,and the anti-coking performance significantly improves,which are highly related to their H/C ratios.Detailed characterisations reveal that the difference of the pyrolysis performance can be ascribed to the content of aromatics and cycloalkanes:the former are prone to initiate secondary reactions to form coking precursors,while the latter could act as the hydrogen donor and release hydrogen,which will terminate the radical propagation reactions and suppress the coke deposition.This work should provide the guidance for upgrading EHFs by modulating the composition of EHFs.

关键词： RP-3 Fuel Pyrolysis Hydrogenation Deposition

维普期刊数据库博看期刊

Toughening additive manufactured Zr-based bulk metallic glass composites by martensite phase transformation

在线全文

学校读者我要写书评

暂无评论

Journal of Materials Science & Technology 2024年第3期170卷 95-102页

作者： Pengcheng Zhang Cheng Zhang Jie pan Di Ouyang Lin liu State Key Laboratory of Materials Processing and Die&Mould Technology School of Materials Science and EngineeringHuazhong University of Science and TechnologyWuhan 430074China

Additive manufacturing technology based on laser powder bed fusion(LPBF)offers a novel approach for fabricating bulk metallic glass(BMG)products without restriction in size and geometry.Nevertheless,the BMGs prepared by LPBF usually suffered from less plasticity and poorer fracture toughness as compared to their cast counterparts due to partial crystallization in heat-affected zones(HAZs).Since crystallization in HAZs is hard to avoid completely in LPBF BMGs,it is desirable to design a suitable alloy system,in which only ductile crystalline phase,instead of brittle intermetallics,is formed in HAZs.This unique structure could effectively increase the toughness/plasticity of the LPBF BMGs.To achieve this goal,a quaternary BMG system with a composition of Zr_(47.5)Cu_(45.5)Al_(5)Co_(2)is adopted and subjected to LPBF.It is found that nearly a single phase of B_(2)-ZrCu is precipitated in HAZs,while a fully amorphous phase is formed in molten pools(MPs).This B_(2)phase reinforced BMG composite exhibits excellent mechanical properties with enhanced plasticity and toughness.Furthermore,it is easy to modulate the mechanical properties by altering the amount of the B_(2)phase via adjusting the laser energy input.Finally,the best combination of strength,plasticity,and notch toughness is obtained in the BMG composite containing 27.4%B_(2)phase and 72.6%amorphous phase,which exhibits yield strength(σ_(s))of 1423 MPa,plastic strain(ε_(p))of 4.65%,and notch toughness(K_(q))of 53.9 MPa m 1/2.Furthermore,a notable strain-hardening is also observed.The improvement of plasticity/toughness and appearance of strain-hardening behavior are mainly due to the martensite phase transformation from the B_(2)phase to the Cm phase during plastic deformation(i.e.,the phase transformation-induced plasticity effect).The current work provides a guide for making advanced BMGs and BMG composites by additive manufacturing.

关键词： Laser powder bed fusion Bulk metallic glass composites Phase transformation-induced plasticity Deformation mechanism

Multivariate statistical and bioinformatic analyses for the seasonal variations of actinobacterial community structures in a drinking water reservoir

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Environmental Sciences 2024年第3期137卷 1-17页

作者： Haihan Zhang Sixuan pan BenMa Tinglin Huang Dmitry B.Kosolapov Manli Ma Xiang liu Huan liu Xiaoyan liu Shaanxi Key Laboratory of Environmental Engineering Key Laboratory of Northwest Water ResourceEnvironment and EcologyMOEXi’an University of Architecture and TechnologyXi’an 710055China School of Environmental and Municipal Engineering Xi’an University of Architecture and TechnologyXi’an 710055China Papanin Institute for Biology of Inland Waters of Russian Academy of Sciences(IBIW RAS) 109BorokNekouzYaroslavl152742Russia

Actinobacterial community is a conspicuous part of aquatic ecosystems and displays an important role in the case of biogeochemical cycle,but little is known about the seasonal variation of actinobacterial community in reservoir ecological environment.In this study,the high-throughput techniques were used to investigate the structure of the aquatic actinobacterial community and its inducing water quality parameters in different seasons.The results showed that the highest diversity and abundance of actinobacterial community occurred in winter,with Sporichthya(45.42%)being the most abundant genus and Rhodococcus sp.(29.32%)being the most abundant species.Network analysis and correlation analysis suggested that in autumn the dynamics of actinobacterial community were infuenced by more factors and Nocardioides sp.SX2R5S2 was the potential keystone species which was negatively correlated with temperature(R=-0.72,P<0.05).Changes in environmental factors could significantly affect the changes in actinobacterial community,and the dynamics of temperature,dissolved oxygen(DO),and turbidity are potential conspicuous factors infuencing seasonal actinobacterial community trends.The partial least squares path modeling further elucidated that the combined effects of DO and temperature not only in the diversity of actinobacterial community but also in other water qualities,while the physiochemical parameters(path coefficient=1.571,P<0.05)was strong environmental factors in natural mixture period.These results strengthen our understanding of the dynamics and structures of actinobacterial community in the drinking water reservoirs and provide scientific guidance for further water quality management and protection in water sources.

关键词： Source water reservoir High-throughput sequencing Correlation analysis Network analysis Partial least squares path modeling

Characteristics of orthorhombic anisotropic seismic response induced by horizontal in situ stress in vertical transversely isotropic media

在线全文

学校读者我要写书评

暂无评论

Science China Earth Sciences 2024年第7期67卷 2291-2310页

作者： Xinpeng pan Chengxu LU Zhizhe ZHAO Jianxin liu School of Geoscience and Info-Physics Central South UniversityChangsha 410083China Hunan Key LabraoryofNonferrous Resoures and Gelogical Dsaster Exloration Central Souh Unvers Changsha 4o03China Key Laboratory of Metallogenic Prediction of Nonferous Metals and Geological Environment Monitoring(Central South University) Ministry of EducationChangsha 410083China PowerChina Zhongnan Engineering Corporation Limited Changsha 410014China

Sedimentary strata typically exhibit the characteristics of transverse isotropy(VTI)with a vertical axis of symmetry.However,fractures in sedimentary strata tend to produce anisotropic closure due to horizontal in situ stress,resulting in pronounced orthorhombic anisotropy in VTI media under such stress conditions and influencing the propagation behavior of seismic waves.Previous studies have primarily focused on the elastic wave velocity anisotropy induced by applied stress in isotropic background media,neglecting the impact of VTI background media on the anisotropy induced by horizontal in situ stress and the response characteristics of seismic wave propagation.To address these gaps,we first establish the effective elastic stiffness tensor of VTI media under horizontal in situ stress using nonlinear acoustoelastic theory.Then,we derive the accurate and linearized approximate equations for P-wave seismic reflectivity of VTI media under horizontal in situ stress,based on wave equations and scattering theory,respectively.Finally,we compare and analyze the characteristics of orthorhombic anisotropic seismic response induced by horizontal in situ stress at various types of elastic reflection interfaces.Our results demonstrate that the linearized approximation of the seismic reflection response characteristics closely aligns with the accurate equations under conditions of small stress below 10 MPa,effectively capturing the azimuth-dependent orthorhombic anisotropy induced by horizontal in situ stress in VTI media.The results of this study also provide a novel theoretical approach and valuable insights into the seismic prediction of in situ stress.

关键词： Horizontal in situ stress Nonlinear acoustoelastic theory Linear slip theory Orthorhombic anisotropy Stress seismic prediction

Clinical efficacy and safety of erlotinib combined with chemotherapy in the treatment of advanced pancreatic cancer:A meta-analysis

在线全文

学校读者我要写书评

暂无评论

World Journal of Gastrointestinal Surgery 2024年第3期16卷 921-931页

作者： Xiao-Yan liu Hong-Nian pan Yue Yu Cheeloo College of Medicine Shandong UniversityJinan 250012Shandong ProvinceChina Department of Gastroenterology The First Affiliated Hospital of USTCDivision of Life Sciences and MedicineUniversity of Science and Technology of ChinaHefei 230001Anhui ProvinceChina Department of Gastroenterology The Lu’an Hospital Affiliated to Anhui Medical UniversityThe Lu’an People's HospitalLu’an 237000Anhui ProvinceChina

BACKGROUND Advanced pancreatic cancer is resistant to chemotherapeutic drugs,resulting in limited treatment efficacy and poor prognosis.Combined administration of the chemotherapeutic gemcitabine and erlotinib is considered a potential first-line treatment for advanced pancreatic cancer.However,their comparative benefits and potential risks remain unclear.AIM To assess the clinical efficacy and safety of erlotinib combined with other chemotherapy regimens for the treatment of advanced pancreatic cancer.METHODS Literature on the clinical efficacy and safety of erlotinib combined with chemotherapy for advanced pancreatic cancer was retrieved through an online search.The retrieved literature was subjected to a methodological qualitative assessment and was analyzed using the RevMan 5.3 software.Ten randomized controlled trials involving 2444 patients with advanced pancreatic cancer were included in the meta-analysis.RESULTS Compared with chemotherapeutic treatment,erlotinib combined with chemotherapy significantly prolonged the progression-free survival time of pancreatic cancer patients[hazard ratio(HR)=0.78,95%CI:0.66-0.92,P=0.003].Meanwhile,the overall survival(HR=0.99,95%CI:0.72-1.37,and P=0.95)and disease control rate(OR=0.93,95%CI:0.45-0.91,P=0.84)were not significantly favorable.In terms of safety,the erlotinib and chemotherapy combination was associated with a significantly higher risk of diarrhea(OR=3.59,95%CI:1.63-7.90,Ppancreatic cancer,but does not improve survival benefit or disease control rate,and can increase the risk of diarrhea and rash.

关键词： Erlotinib Chemotherapy Advanced pancreatic cancer Efficacy Safety Meta-analysis

The essential roles of m^(6)A modification in osteogenesis and common bone diseases

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Genes & Diseases 2024年第1期11卷 335-345页

作者： Yuxi Gu Yidan Song Yihua pan Jun liu State Key Laboratory of Oral Diseases&National Clinical Research Center for Oral Diseases Department of OrthodonticsWest China Hospital of StomatologySichuan UniversityChengduSichuan 610041China

N6-methyladenosine(m^(6)A)is the most prevalent modification in the eukaryotic transcriptome and has a wide range of functions in coding and noncoding RNAs.It affects the fate of the modified RNA,including its stability,splicing,and translation,and plays an important role in post-transcriptional regulation.Bones play a key role in supporting and pro-tecting muscles and other organs,facilitating the movement of the organism,ensuring blood production,etc.Bone diseases such as osteoarthritis,osteoporosis,and bone tumors are serious public health problems.The processes of bone development and osteogenic differen-tiation require the precise regulation of gene expression through epigenetic mechanisms including histone,DNA,and RNA modifications.As a reversible dynamic epigenetic mark,m^(6)A modifications affect nearly every important biological process,cellular component,and molecular function,including skeletal development and homeostasis.In recent years,studies have shown that m^(6)A modification is involved in osteogenesis and bone-related diseases.In this review,we summarized the proteins involved in RNA m^(6)A modification and the latest progress in elucidating the regulatory role of m^(6)A modification in bone formation and stem cell direc-tional differentiation.We also discussed the pathological roles and potential molecular mech-anisms of m^(6)A modification in bone-related diseases like osteoporosis and osteosarcoma and suggested potential areas for new strategies that could be used to prevent or treat bone de-fects and bone diseases.

关键词： Bone diseases m^(6)A modification Osteogenesis Regulatory role Stem cells