检索结果-南通市图书馆

Journal of Environmental Sciences 2020年第2期32卷 187-199页

作者： Shuyu Liu Renjun Yang Nuoya Yin Francesco Faiola State Key Laboratory of Environmental Chemistry and Ecotoxicology Research Center for Eco-Environmental SciencesChinese Academy of SciencesBeijing 100085China College of Resources and Environment University of Chinese Academy of SciencesBeijing 100049China Wellcome Trust/CRUK Gurdon Institute Department of PathologyUniversity of CambridgeCambridge CB21QNUK

Per-and polyfluorinated alkyl substances(PFASs) are commonly used in industrial processes and daily life products.Because they are persistent, they accumulate in the environment, wildlife and humans.Although many studies have focused on two of the most representative PFASs, PFOS and PFOA, the potential toxicity of short-chain PFASs has not yet been given sufficient attention.We used a battery of assays to evaluate the toxicity of several four-carbon and six-carbon perfluorinated sulfonates and carboxyl acids(PFBS,PFHxS, PFBA and PFHxA), with a human mesenchymal stem cell(hMSC) system.Our results demonstrate significant cyto-and potential developmental toxicity for all the compounds analyzed, with shared but also distinct mechanisms of toxicity.Moreover, the effects of PFBS and PFHxS were stronger than those of PFBA and PFHxA, but occurred at higher doses compared to PFOS or PFOA.

关键词： Short-chain perfluorinated compounds Human mesenchymal stem cells(hMSCs) Adipogenesis/osteogenesis Developmental toxicity PFBS/PFBA/PFHxS/PFHxA

Developmental toxicity assessment of neonicotinoids and organophosphate esters with a human embryonic stem cell-and metabolism-based fast-screening model

在线全文

学校读者我要写书评

暂无评论

Journal of Environmental Sciences 2024年第3期137卷 370-381页

作者： Shuxian Zhang Miaomiao Zhao Shichang Li Renjun Yang Nuoya Yin Francesco Faiola State Key Laboratory of Environmental Chemistry and Ecotoxicology Research Center for Eco-Environmental SciencesChinese Academy of SciencesBeijing 100085China College of Resources and Environment University of Chinese Academy of SciencesBeijing 100049China

In recent years,neonicotinoids(NEOs)and organophosphate esters(OPEs)have been widely used as substitutes for traditional pesticides and brominated fame-retardants,respectively.Previous studies have shown that those compounds can be frequently detected in environmental and human samples,are able to penetrate the placental barrier,and are toxic to animals.Thus,it is reasonable to speculate that NEOs and OPEs may have potential adverse effects in humans,especially during development.We employed a human embryonic stem cell differentiation-and liver S9 fraction metabolism-based fast screening model to assess the potential embryonic toxicity of those two types of chemicals.We show that four NEO and five OPE prototypes targeted mostly ectoderm specification,as neural ectoderm and neural crest genes were down-regulated,and surface ectoderm and placode markers up-regulated.Human liver S9 fraction's treatment could generally reduce the effects of the chemicals,except in a few specific instances,indicating the liver may detoxify NEOs and OPEs.Our findings suggest that NEOs and OPEs interfere with human early embryonic development.

关键词： Neonicotinoids Organophosphate esters Human embryonic stem cells Fast screening model Developmental toxicity

High-emitter identification for heavy-duty vehicles by temporal optimization LSTM and an adaptive dynamic threshold

在线全文

学校读者我要写书评

暂无评论

Frontiers of Information Technology & Electronic Engineering 2023年第11期24卷 1633-1646页

作者： Zhenyi XU renjun WANG yang CAO Yu KANG Institute of Artificial Intelligence Hefei Comprehensive National Science CenterHefei 230088China AHU-IAI AI Joint Laboratory Anhui UniversityHefei 230601China Department of Automation University of Science and Technology of ChinaHefei 230027China Institute of Advanced Technology University of Science and Technology of ChinaHefei 230088China

Heavy-duty diesel vehicles are important sources of urban nitrogen oxides(NOx)in actual applications for environmental compliance,emitting more than 80%of NOx and more than 90%of particulate matter(PM)in total vehicle emissions.The detection and control of heavy-duty diesel emissions are critical for protecting public health.Currently,vehicles on the road must be regularly tested,every six months or once a year,to filter out high-emission mobile sources at vehicle inspection stations.However,it is difficult to effectively screen high-emission vehicles in time with a long interval between annual inspections,and the fixed threshold cannot adapt to the dynamic changes of vehicle driving conditions.An on-board diagnostic device(OBD)is installed inside the vehicle and can record the vehicle’s emission data in real time.In this paper,we propose a temporal optimization long short-term memory(LSTM)and adaptive dynamic threshold approach to identify heavy-duty high-emitters by using OBD data,which can continuously track and record the emission status in real time.First,a temporal optimization LSTM emission prediction model is established to solve the attention bias discrepancy problem on time steps that is caused by the large number of OBD data streams in practice.Then,the concentration prediction error sequence is detected and distinguished from the anomalous emission contexts using flexible criteria,calculated by an adaptive dynamic threshold with changing driving conditions.Finally,a similarity metric strategy for the time series is introduced to correct some pseudo anomalous results.Experiments on three real OBD time-series emission datasets demonstrate that our method can achieve high accuracy anomalous emission identification.

关键词： High-emitter identification Temporal optimization On-board diagnostic device(OBD) Dynamic threshold

Heat Transfer Problem for the Boltzmann Equation in a Channel with Diffusive Boundary Condition

在线全文

学校读者我要写书评

暂无评论

Chinese Annals of Mathematics,Series B 2022年第6期43卷 1071-1100页

作者： renjun DUAN Shuangqian LIU Tong yang Zhu ZHANG Department of Mathematics The Chinese University of Hong KongShatinHong KongChina School of Mathematics and Statistics and Hubei Key Laboratory of Mathematical Sciences Central China Normal UniversityWuhan 430079China Department of Applied Mathematics The Hong Kong Polytechnic UniversityHong KongChina.

In this paper,the authors study the 1 D steady Boltzmann flow in a channel.The walls of the channel are assumed to have vanishing velocity and given temperaturesθ0andθ1.This problem was studied by Esposito-Lebowitz-Marra(1994,1995)where they showed that the solution tends to a local Maxwellian with parameters satisfying the compressible Navier-Stokes equation with no-slip boundary condition.However,a lot of numerical experiments reveal that the fluid layer does not entirely stick to the boundary.In the regime where the Knudsen number is reasonably small,the slip phenomenon is significant near the boundary.Thus,they revisit this problem by taking into account the slip boundary conditions.Following the lines of[Coron,F.,Derivation of slip boundary conditions for the Navier-Stokes system from the Boltzmann equation,J.Stat.Phys.,54(3-4),1989,829-857],the authors will first give a formal asymptotic analysis to see that the flow governed by the Boltzmann equation is accurately approximated by a superposition of a steady CNS equation with a temperature jump condition and two Knudsen layers located at end points.Then they will establish a uniform L∞estimate on the remainder and derive the slip boundary condition for compressible Navier-Stokes equations rigorously.

关键词： Boltzmann equation Compressible Navier-Stokes approximation Slip boundary conditions Chapman-Enskog expansion

MAGAN:Unsupervised Low-Light Image Enhancement Guided by Mixed-Attention

在线全文

学校读者我要写书评

暂无评论

Big Data Mining and Analytics 2022年第2期5卷 110-119页

作者： renjun Wang Bin Jiang Chao yang Qiao Li Bolin Zhang the College of Computer Science and Electronic Engineering Hunan UniversityChangsha 410006China

Most learning-based low-light image enhancement methods typically suffer from two problems.First,they require a large amount of paired data for training,which are difficult to acquire in most cases.Second,in the process of enhancement,image noise is difficult to be removed and may even be amplified.In other words,performing denoising and illumination enhancement at the same time is difficult.As an alternative to supervised learning strategies that use a large amount of paired data,as presented in previous work,this paper presents an mixed-attention guided generative adversarial network called MAGAN for low-light image enhancement in a fully unsupervised fashion.We introduce a mixed-attention module layer,which can model the relationship between each pixel and feature of the image.In this way,our network can enhance a low-light image and remove its noise simultaneously.In addition,we conduct extensive experiments on paired and no-reference datasets to show the superiority of our method in enhancing low-light images.

关键词： low-light image enhancement unsupervised learning Generative Adversarial Network(GAN) mixedattention

Risk-based Two-stage Optimal Scheduling of Energy Storage System with Second-life Battery Units

在线全文

学校读者我要写书评

暂无评论

CSEE Journal of Power and Energy Systems 2023年第2期9卷 529-538页

作者： Yongxi Zhang Jiahua Zhu Yan Xu renjun Zhou Zhao yang Dong School of Electrical and Information Engineering Changsha University of Science and TechnologyChangsha 410114China School of Electrical&Electronic Engineering Nanyang Technological UniversitySingapore The University of Sydney Sydney 2052Australia

With the growing adoption of Electrical Vehicles(EVs),it is expected that a large number of on-board Li-ion batteries will be retired from EVs in the near future.Retired batteries will typically retain 80%of their initial capacities and can be recycled as second life batteries(SLBs).Although the capital costs of SLBs are much cheaper,their operational reliability is an important concern since used batteries may suffer from a higher failure rate.This paper aggregates brand new batteries and SLBs together to improve power system’s operating performance with renewable energy resources.In the context of a day-ahead and intra-day dispatch framework,a two-stage coordinated optimal scheduling method is proposed.Specifically,the energy cost of brand-new batteries and SLBs is calculated based on detailed battery degradation model,and the reliability of batteries is modeled based on the Weibull distribution.Moreover,Conditional value at risk(CVaR)criterion is applied to evaluate the risk induced by intermittent renewable power output,load demand variation and SLBs failure probability.Simulation tests demonstrate the effectiveness of the proposed method.

关键词： Conditional value at risk reliability second life batteries

Determination of the Cement Sheath Interface and the Causes of Failure in the Completion Stage of Gas Wells

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Fluid Dynamics & Materials Processing 2022年第6期18卷 1719-1735页

作者： Xuesong Xing renjun Xie Yi Wu Zhiqiang Wu Huanqiang yang CNOOC Research Institute Beijing100027China yangtze University Wuhan430100China

The bonding quality of the cement sheath interface decreases during well completion because of the change in the casing pressure.To explore the root cause of such phenomena,experiments on the mechanical properties and interface bonding strength of a cement sheath have been carried out taking the LS25-1 high-temperature and high-pressure(HTHP)gas field as an example.Moreover,a constitutive model of the cement sheath has been defined and verified both by means of a full-scale HTHP cement sheath sealing integrity evaluation experiment and three-dimensional finite element simulations.The results show that the low initial cementing surface strength is the root cause of cement sheath interface bonding failure.When the pressure in the casing exceeds a certain limit,the stress caused by the change in the internal pressure in the casing is transmitted to the cement sheath,resulting in the degradation of the interface stiffness of the cement sheath.However,with an increase in the casing wall thickness,the stress transmission capacity decreases.Therefore,it is concluded that improving the interfacial cementing strength,appropriately increasing the casing wall thickness and increasing the initial stress of the cement sheath are the keys to ensuring the sealing integrity of the cement sheath in high-temperature and high-pressure gas wells.

关键词： Gas well completion cement sheath sealing failure interfacial bonding strength damage plasticity model

Analysis of the Microstructure of a Failed Cement Sheath Subjected to Complex Temperature and Pressure Conditions

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Fluid Dynamics & Materials Processing 2023年第2期19卷 399-406页

作者： Zhiqiang Wu Yi Wu renjun Xie Jin yang Shujie Liu Qiao Deng China University of Petroleum Beijing102249China CNOOC Research Institute Beijing100027China Zhanjiang Branch CNOOC Energy Technology&Services LimitedZhanjiang524057China yangtze University Wuhan430100China

One of the main obstacles hindering the exploitation of high-temperature and high-pressure oil and gas is the sealing integrity of the cement sheath.Analyzing the microstructure of the cement sheath is therefore an important task.In this study,the microstructure of the cement sheath is determined using a CT scanner under different temperature and pressure conditions.The results suggest that the major cause of micro-cracks in the cement is the increase in the casing pressure.When the micro-cracks accumulate to a certain extent,the overall structure of the cement sheath is weakened,resulting in gas channeling,which poses a direct threat to the safe production of oil and gas.A change in the casing temperature has a limited effect on the microstructure of the cement sheath.

关键词： Cement sheath microstructure experimental study mesh model CT scan

Gene Clone and Characterization of a Novel Thermostable β-Galactosidase with Transglycosylation Activity from Thermotoga naphthophila RUK-10

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Chemical Research in Chinese Universities 2015年第4期31卷 564-568页

作者： yang Jingwen DI Xiangjun WANG Man GAO renjun Key Laboratory for Molecular Enzymology and Engineering Ministry of Education School of Life Science Jilin University Changchun 130012 P. R. China

We cloned and expressed a new recombinant β-galactosidase（TN0949） from Thermotoga naphthophila RKU-10 with the pET28a（＋） vector system in Escherichia coli BL21（DE3）, and determined its catalytic capability to synthesize alkyl glucosides. The recombinant enzyme was purified to a single band via heat treatment and Ni2＋-NTA affinity chromatography. The molecular mass of the recombinant enzyme was estimated to be 79 kDa with sodium dodecyl sulfate-polyacrylamide gel electrophoresis（SDS-PAGE）. TN0949 can hydrolyze o-nitrophenylβ-D- galactopyranoside at the optimum pH and temperature of 6.5 and 80 ℃, respectively. TN0949 can also hydrolyze lactose at the optimum pH and temperature of 5.2 and 80 ℃, respectively. The Km values for the hydrolyses of o-nitrophenyl fl-D-galactopyranoside and lactose were 0.82 and 83.65 mmol/L, respectively. TN0949 was stable over a wide range of pH（3.0 to 7.0） after 24 h of incubation. The half-lives of TN0949 at 75, 80 and 85 ℃ were 22, 6 and 1.33 h, respectively. The enzyme displayed the capability to use lactose as the transglycosylation substrate to synthesize butyl galactopyranoside and hexyl galactopyranoside, indicating its suitability as a candidate industrial biocatalyst.

关键词： β-Galactosidase Thermostable Transglycosylation

Flexible bidirectional self-powered photodetector with significantly reduced volume and accelerated response speed based on hydrogel and lift-off GaN-based nanowires

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Fundamental Research 2024年第2期4卷 369-378页

作者： Min Jiang Yukun Zhao Penghui Zheng Jianya Zhang Wenxian yang Min Zhou Yuanyuan Wu renjun Pei Shulong Lu Key Lab of Nanodevices and Applications Suzhou Institute of Nano-Tech and Nano-Bionics(SINANO)Chinese Academy of Sciences(CAS)Suzhou 215123China School of Nano-Tech and Nano-Bionics University of Science and Technology of ChinaHefei 230026China CAS Key Laboratory of Nano-Bio Interface Suzhou Institute of Nano-Tech and Nano-BionicsChinese Academy of SciencesSuzhou 215123China Nanchang Research Institute Suzhou Institute of Nano-Tech and Nano-BionicsChinese Academy of SciencesNanchang 330200China

Due to the wide range of potential applications for next-generation multi-functional devices,the flexible selfpowered photodetector(PD)with polarity-switchable behavior is essential but very challenging to be realized.Herein,a wearable bidirectional self-powered PD based on detached(Al,Ga)N and(In,Ga)N nanowires has been proposed and demonstrated successfully.Arising from the photovoltage-competing dynamics across(Al,Ga)N and(In,Ga)N nanowire photoelectrodes,such PD can generate the positive(33.3 mA W−1)and negative(-0.019 mA W−1)photo-responsivity under ultraviolet(UV)and visible illumination,respectively,leading to the bidirectional photocurrent behavior.Thanks to the introduction of quasi solid-state hydrogel,the PD can work without the liquid-electrolyte,thus remarkably reducing the volume from about 482 cm3 to only 0.18 cm3.Furthermore,the use of hydrogel is found to enhance response speed in the UV range by reducing the response time for more than 95%,which is mainly attributed to the increased open circuit potential and reduced ion transport distance.As the GaN connecting segment is pretty thin,the piezoelectric charges generated by stress are proposed to have only a limited effect on the photocurrent density.Therefore,both the stable on-off switching characteristics and photocurrent densities can still be achieved after being bent 400 times.With an excellent flexibility,this work creates opportunities for technological applications of bidirectional photocurrent PDs in flexible optoelectronic devices,e.g.,wearable intelligent sensors.

关键词： Flexible photodetector Bidirectional photocurrent Lift-off GaN-based nanowires Hydrogel Self-powered device