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Detection accuracy of target accelerations based on vortex electromagnetic wave in keyhole space
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作者 郭凯 雷爽 +2 位作者 雷艺 周红平 郭忠义 《Chinese Physics B》 SCIE EI CAS CSCD 2024年第2期283-290,共8页
The influence of the longitudinal acceleration and the angular acceleration of detecting target based on vortex electromagnetic waves in keyhole space are analyzed.The spectrum spreads of different orbital angular mom... The influence of the longitudinal acceleration and the angular acceleration of detecting target based on vortex electromagnetic waves in keyhole space are analyzed.The spectrum spreads of different orbital angular momentum(OAM)modes in different non-line-of-sight situations are simulated.The errors of target accelerations in detection are calculated and compared based on the OAM spectra spreading by using two combinations of composite OAM modes in the keyhole space.According to the research,the effects about spectrum spreads of higher OAM modes are more obvious.The error in detection is mainly affected by OAM spectrum spreading,which can be reduced by reasonably using different combinations of OAM modes in different practical situations.The above results provide a reference idea for investigating keyhole effect when vortex electromagnetic wave is used to detect accelerations. 展开更多
关键词 vortex electromagnetic waves detect accelerations keyhole space spectrum spread
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Quantum Spin Exchange Interactions to Accelerate the Redox Kinetics in Li–S Batteries
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作者 Yu Du Weijie Chen +4 位作者 Yu Wang Yue Yu kai guo Gan Qu Jianan Zhang 《Nano-Micro Letters》 SCIE EI CAS CSCD 2024年第5期370-383,共14页
Spin-engineering with electrocatalysts have been exploited to suppress the“shuttle effect”in Li–S batteries.Spin selec-tion,spin-dependent electron mobility and spin potentials in activation barriers can be optimiz... Spin-engineering with electrocatalysts have been exploited to suppress the“shuttle effect”in Li–S batteries.Spin selec-tion,spin-dependent electron mobility and spin potentials in activation barriers can be optimized as quantum spin exchange interactions lead-ing to a significant reduction of the electronic repulsions in the orbitals of catalysts.Herein,we anchor the MgPc molecules on fluorinated carbon nanotubes(MgPc@FCNT),which exhibits the single active Mg sites with axial displacement.According to the density functional theory calculations,the electronic spin polarization in MgPc@FCNT not only increases the adsorption energy toward LiPSs intermediates but also facilitates the tunneling process of electron in Li–S batter-ies.As a result,the MgPc@FCNT provides an initial capacity of 6.1 mAh cm^(-2) even when the high sulfur loading is 4.5 mg cm^(-2),and still maintains 5.1 mAh cm^(-2) after 100 cycles.This work provides a new perspective to extend the main group single-atom catalysts enabling high-performance Li–S batteries. 展开更多
关键词 Metal phthalocyanines Spin polarization ELECTROCATALYSIS Li–S batteries
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A sustainable process to 100%bio-based nylons integrated chemical and biological conversion of lignocellulose
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作者 Ruijia Hu Ming Li +9 位作者 Tao Shen Xin Wang Zhuohua Sun Xinning Bao Kequan Chen kai guo Lei Ji Hanjie Ying Pingkai Ouyang Chenjie Zhu 《Green Energy & Environment》 SCIE EI CAS CSCD 2024年第2期390-402,共13页
Considerable progress has been made in recent years to the development of sustainable polymers from bio-based feedstocks.In this study,100%bio-based nylons were prepared via an integrated chemical and biological proce... Considerable progress has been made in recent years to the development of sustainable polymers from bio-based feedstocks.In this study,100%bio-based nylons were prepared via an integrated chemical and biological process from lignocellulose.These novel nylons were obtained by the melt polymerization of 3-propyladipic acid derived from lignin and 1,5-pentenediamine/1,4-butanediamine derived from carbohydrate sugar.Central to the concept is a three-step noble metal free catalytic chemical funnelling sequence(Raney Ni mediated reductive catalytic fractionation-reductive funnelling-oxidative funnelling),which allowed for obtaining a single component 3-propyladipic acid from lignin with high efficiency.The structural and thermodynamic properties of the obtained nylons have been systematically investigated,and thus obtained transparent bio-based nylons exhibited higher Mw(>32,000)and excellent thermal stability(Td5%>265℃).Considering their moderate Tg and good melt strength,these transparent bio-based nylons could serve as promising functional additives or temperature-responsive materials. 展开更多
关键词 LIGNOCELLULOSE LIGNIN Reductive catalytic fractionation Bio-based nylon
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Microfluidic field strategy for enhancement and scale up of liquid-liquid homogeneous chemical processes by optimization of 3D spiral baffle structure 被引量:1
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作者 Shuangfei Zhao Yingying Nie +7 位作者 Wenyan Zhang Runze Hu Lianzhu Sheng Wei He Ning Zhu Yuguang Li Dong Ji kai guo 《Chinese Journal of Chemical Engineering》 SCIE EI CAS CSCD 2023年第4期255-265,共11页
Due to the scale effect, the uniform distribution of reagents in continuous flow reactor becomes bad when the channel is enlarged to tens of millimeters. Microfluidic field strategy was proposed to produce high mixing... Due to the scale effect, the uniform distribution of reagents in continuous flow reactor becomes bad when the channel is enlarged to tens of millimeters. Microfluidic field strategy was proposed to produce high mixing efficiency in large-scale channel. A 3D spiral baffle structure(3SBS) was designed and optimized to form microfluidic field disturbed by continuous secondary flow in millimeter scale Y-shaped tube mixer(YSTM). Enhancement effect of the 3SBS in liquid-liquid homogeneous chemical processes was verified and evaluated through the combination of simulation and experiment. Compared with 1 mm YSTM, 10 mm YSTM with 3SBS increased the treatment capacity by 100 times, shortened the basic complete mixing time by 0.85 times, which proves the potential of microfluidic field strategy in enhancement and scale-up of liquid-liquid homogeneous chemical process. 展开更多
关键词 Mixing efficiency Chemical process intensification Scale up REACTOR Computational fluid dynamics(CFD) Numerical simulation
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Cs-Induced Phase Transformation of Vanadium Oxide for High-Performance Zinc-Ion Batteries 被引量:1
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作者 Gan Qu kai guo +4 位作者 Weijie Chen Yu Du Ye Wang Bingbing Tian Jianan Zhang 《Energy & Environmental Materials》 SCIE EI CAS CSCD 2023年第4期265-272,共8页
Rechargeable aqueous zinc-ion batteries are promising candidate for gridscale energy storage.However,the development of zinc-ion batteries has been plagued by the lack of cathode materials with high specific capacity ... Rechargeable aqueous zinc-ion batteries are promising candidate for gridscale energy storage.However,the development of zinc-ion batteries has been plagued by the lack of cathode materials with high specific capacity and superior lifespan.Herein,hexagonal Cs_(0.3)V_(2)O_(5)cathode is fabricated and investigated in zinc-ion batteries.Compared with the traditional vanadium oxides,the introduction of Cs changes the periodic atomic arrangements,which not only stabilizes the open framework structure but also facilitates the Zn^(2+)diffusion with a lower migration energy barrier.Consequently,high specific capacity of 543.8 mA h g^(-1)at 0.1 A g^(-1)is achieved,which surpasses most of reported cathode materials in zinc-ion batteries.The excellent cycle life is achieved over 1000 cycles with about 87.8%capacity retention at 2 A g^(-1).Furthermore,the morphological evolution and energy storage mechanisms are also revealed via a series of techniques.This work opens up a phase engineering strategy to fabricate the hexagonal vanadium oxide and elucidate the application of phase-dependent cathodes in zinc-ion batteries. 展开更多
关键词 cathode materials phase engineering vanadium oxide zinc-ion batteries
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Melatonin inhibits ESCC tumor growth by mitigating the HDAC7/β-catenin/c-Myc positive feedback loop and suppressing the USP10-maintained HDAC7 protein stability
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作者 Zhi-Qiang Ma Ying-Tong Feng +13 位作者 kai guo Dong Liu Chang-Jian Shao Ming-Hong Pan Yi-Meng Zhang Yu-Xi Zhang Di Lu Di Huang Fan Zhang Jin-Liang Wang Bo Yang Jing Han Xiao-Long Yan Yi Hu 《Military Medical Research》 SCIE CAS CSCD 2023年第2期207-226,共20页
Background:Melatonin,a natural hormone secreted by the pineal gland,has been reported to exhibit antitumor properties through diverse mechanisms of action.However,the oncostatic function of melatonin on esophageal squ... Background:Melatonin,a natural hormone secreted by the pineal gland,has been reported to exhibit antitumor properties through diverse mechanisms of action.However,the oncostatic function of melatonin on esophageal squamous cell carcinoma(ESCC) remains elusive.This study was conducted to investigate the potential effect and underlying molecular mechanism of melatonin as single anticancer agent against ESCC cells.Methods:ESCC cell lines treated with or without melatonin were used in this study.In vitro colony formation and 5-Ethynyl-2’-deoxyuridine(EdU) incorporation assays,and nude mice tumor xenograft model were used to confirm the proliferative capacities of ESCC cells.RNA-seq,qPCR,Western blotting,recombinant lentivirus-mediated target gene overexpression or knockdown,plasmids transfection and co-IP were applied to investigate the underlying molecular mechanism by which melatonin inhibited ESCC cell growth.IHC staining on ESCC tissue microarray and further survival analyses were performed to explore the relationship between target genes’ expression and prognosis of ESCC.Results:Melatonin treatment dose-dependently inhibited the proliferative ability and the expression of histone deacetylase 7(HDAC7),c-Myc and ubiquitin-specific peptidase 10(USP10) in ESCC cells(P<0.05).The expressions of HDAC7,c-Myc and USP10 in tumors were significantly higher than the paired normal tissues from 148 ESCC patients(P<0.001).Then,the Kaplan-Meier survival analysis suggested that ESCC patients with high HDAC7,c-Myc or USP10levels predicted worse overall survival(log-rank P<0.001).Co-IP and Western blotting further revealed that HDAC7physically deacetylated and activated β-catenin thus promoting downstream target c-Myc gene transcription.Notably,our mechanistic study validated that HDAC7/β-catenin/c-Myc could form the positive feedback loop to enhance ESCC cell growth,and USP10 could deubiquitinate and stabilize HDAC7 protein in the ESCC cells.Additionally,we verified that inhibition of the HDAC7/β-catenin/c-Myc axis and USP10/HDAC7 pathway mediated the anti-proliferative action of melatonin on ESCC cells.Conclusions:Our findings elucidate that melatonin mitigates the HDAC7/β-catenin/c-Myc positive feedback loop and inhibits the USP10-maintained HDAC7 protein stability thus suppressing ESCC cell growth,and provides the reference for identifying biomarkers and therapeutic targets for ESCC. 展开更多
关键词 MELATONIN Histone deacetylase 7(HDAC7) Β-CATENIN C-MYC Ubiquitin-specifc peptidase 10(USP10) Esophageal squamous cell carcinoma(ESCC)
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Obtaining accurate measurements of the sea surface height from a GPS buoy
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作者 Wanlin Zhai Jianhua Zhu +5 位作者 Chuntao Chen Wu Zhou Longhao Yan Yufei Zhang Xiaoqi Huang kai guo 《Acta Oceanologica Sinica》 SCIE CAS CSCD 2023年第6期78-88,共11页
A dedicated GPS buoy is designed for calibration and validation(Cal/Val)of satellite altimeters since 2014.In order to evaluate the accuracy of the sea surface height(SSH)measured by the GPS buoy,twelve campaigns have... A dedicated GPS buoy is designed for calibration and validation(Cal/Val)of satellite altimeters since 2014.In order to evaluate the accuracy of the sea surface height(SSH)measured by the GPS buoy,twelve campaigns have been done within China sea area between 2014 and 2021.In six of these campaigns,two static Global Navigation Satellite System stations were installed at distances of<1 km and 19 km from the buoy to assess how the baseline length influenced the derived SSH from the buoy solutions.The GPS buoy data was processed using the GAMIT/GLOBK software+TRACK module and CSRS-PPP tool to achieve the SSH.The SSH was compared with conventionally tide gauge(TG)data to evaluate the accuracy of the buoy with the standard deviation of the height element.The results showed that the difference in the standard deviation of the SSH from the buoy and the TG was less than 16 mm.The SSHs processed with different ephemeris(Ultra-Rapid,Rapid,Final)were not significantly different.When the baseline length was 19 km,the SSH solution of the GPS buoy performed well,with standard bias of less than 26 mm between the heights measured by the buoy and TG,meaning that the buoy could be used for Cal/Val of altimeters.The bias between the Canadian Spatial Reference System-precise point positioning tool and the TRACK varied a lot,and some of them were over 130 mm.This deemed too high to be useful for Cal/Val of satellite altimeters.Moreover,the GPS buoy solutions processed by GAMIT/GLOBK software+TRACK module were used for in-orbit Cal/Val of HY-2B/C satellites in ten campaigns.The SSH and significant wave height of the altimeters showed good agreements with the GPS buoy solutions. 展开更多
关键词 GPS buoy sea surface height baseline length precise point positioning satellite altimeter HY-2
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Quantum cascade lasers grown by MOCVD
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作者 Yongqiang Sun Guangzhou Cui +10 位作者 kai guo Jinchuan Zhang Ning Zhuo Lijun Wang Shuman Liu Zhiwei Jia Teng Fei Kun Li Junqi Liu Fengqi Liu Shenqiang Zhai 《Journal of Semiconductors》 EI CAS CSCD 2023年第12期47-63,共17页
Sharing the advantages of high optical power,high efficiency and design flexibility in a compact size,quantum cascade lasers(QCLs)are excellent mid-to-far infrared laser sources for gas sensing,infrared spectroscopic,... Sharing the advantages of high optical power,high efficiency and design flexibility in a compact size,quantum cascade lasers(QCLs)are excellent mid-to-far infrared laser sources for gas sensing,infrared spectroscopic,medical diagnosis,and defense applications.Metalorganic chemical vapor deposition(MOCVD)is an important technology for growing high quality semiconductor materials,and has achieved great success in the semiconductor industry due to its advantages of high efficiency,short maintenance cycles,and high stability and repeatability.The utilization of MOCVD for the growth of QCL materials holds a significant meaning for promoting the large batch production and industrial application of QCL devices.This review summarizes the recent progress of QCLs grown by MOCVD.Material quality and the structure design together determine the device performance.Research progress on the performance improvement of MOCVD-grown QCLs based on the optimization of material quality and active region structure are mainly reviewed. 展开更多
关键词 quantum cascade lasers continuous wave high optical power metal organic chemical vapor deposition broad gain
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Hydralazine Promotes Central Nervous System Recovery after Spinal Cord Injury by Suppressing Oxidative Stress and Inflammation through Macrophage Regulation
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作者 Xin QUAN Teng MA +4 位作者 kai guo Huan WANG Cai-yong YU Chu-chu QI Bao-qiang SONG 《Current Medical Science》 SCIE CAS 2023年第4期749-758,共10页
Objective:This study aims to investigate the effects of hydralazine on inflammation induced by spinal cord injury(SCI)in the central nervous system(CNS)and its mechanism in promoting the structural and functional reco... Objective:This study aims to investigate the effects of hydralazine on inflammation induced by spinal cord injury(SCI)in the central nervous system(CNS)and its mechanism in promoting the structural and functional recovery of the injured CNS.Methods:A compressive SCI mouse model was utilized for this investigation.Immunofluorescence and quantitative real-time polymerase chain reaction were employed to examine the levels of acrolein,acrolein-induced inflammation-related factors,and macrophages at the injury site and within the CNS.Western blotting was used to evaluate the activity of the phosphoinositide 3-kinase(PI3K)/AKT pathway to study macrophage regulation.The neuropathic pain and motor function recovery were evaluated by glutamic acid decarboxylase 65/67(GAD65/67),vesicular glutamate transporter 1(VGLUT1),paw withdrawal response,and Basso Mouse Scale score.Nissl staining and Luxol Fast Blue(LFB)staining were performed to investigate the structural recovery of the injured CNS.Results:Hydralazine downregulated the levels of acrolein,IL-1β,and TNF-αin the spinal cord.The downregulation of acrolein induced by hydralazine promoted the activation of the PI3K/AKT pathway,leading to M2 macrophage polarization,which protected neurons against SCI-induced inflammation.Additionally,hydralazine promoted the structural recovery of the injured spinal cord area.Mitigating inflammation and oxidative stress by hydralazine in the animal model alleviated neuropathic pain and altered neurotransmitter expression.Furthermore,hydralazine facilitated motor function recovery following SCI.Nissl staining and LFB staining indicated that hydralazine promoted the structural recovery of the injured CNS.Conclusion:Hydralazine,an acrolein scavenger,significantly mitigated SCI-induced inflammation and oxidative stress in vivo,modulated macrophage activation,and consequently promoted the structural and functional recovery of the injured CNS. 展开更多
关键词 spinal cord injury proinflammation oxidative stress MACROPHAGE acrolein scavenger
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Correction to:Molecular characterization and functional analysis of daf-8 in the pinewood nematode,Bursaphelenchus xylophilus
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作者 Jinghan Wang Huan Hong +7 位作者 Rong Xie Jingjing Ji kai guo Liqun Bai Jia Tang Hongshi Yu Jianren Ye Jiafu Hu 《Journal of Forestry Research》 SCIE CAS CSCD 2023年第5期1651-1651,共1页
Correction to:J.For.Res.(2022)33:689–698 https://doi.org/10.1007/s11676-021-01335-7 In the Original Publication,the text“Acknowledgements sdfkjds”has been inadvertently appeared in the paper.The Original article ha... Correction to:J.For.Res.(2022)33:689–698 https://doi.org/10.1007/s11676-021-01335-7 In the Original Publication,the text“Acknowledgements sdfkjds”has been inadvertently appeared in the paper.The Original article has been corrected. 展开更多
关键词 KNOWLEDGE characterization FUNCTIONAL
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Diagnostic accuracy of apparent diffusion coefficient to differentiate intrapancreatic accessory spleen from pancreatic neuroendocrine tumors
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作者 Shuai Ren kai guo +3 位作者 Yuan Li Ying-Ying Cao Zhong-Qiu Wang Ying Tian 《World Journal of Gastrointestinal Oncology》 SCIE 2023年第6期1051-1061,共11页
BACKGROUND Intrapancreatic accessory spleen(IPAS)shares similar imaging findings with hypervascular pancreatic neuroendocrine tumors(PNETs),which may lead to unnecessary surgery.AIM To investigate and compare the diag... BACKGROUND Intrapancreatic accessory spleen(IPAS)shares similar imaging findings with hypervascular pancreatic neuroendocrine tumors(PNETs),which may lead to unnecessary surgery.AIM To investigate and compare the diagnostic performance of absolute apparent diffusion coefficient(ADC)and normalized ADC(lesion-to-spleen ADC ratios)in the differential diagnosis of IPAS from PNETs.METHODS A retrospective study consisting of 29 patients(16 PNET patients vs 13 IPAS patients)who underwent preoperative contrast-enhanced magnetic resonance imaging together with diffusion-weighted imaging/ADC maps between January 2017 and July 2020 was performed.Two independent reviewers measured ADC on all lesions and spleens,and normalized ADC was calculated for further analysis.The receiver operating characteristics analysis was carried out for evaluating the diagnostic performance of both absolute ADC and normalized ADC values in the differential diagnosis between IPAS and PNETs by clarifying sensitivity,specificity,and accuracy.Inter-reader reliability for the two methods was evaluated.RESULTS IPAS had a significantly lower absolute ADC(0.931±0.773×10^(-3)mm^(2)/s vs 1.254±0.219×10^(-3)mm^(2)/s)and normalized ADC value(1.154±0.167 vs 1.591±0.364)compared to PNET.A cutoff value of 1.046×10^(-3)mm^(2)/s for absolute ADC was associated with 81.25%sensitivity,100%specificity,and 89.66%accuracy with an area under the curve of 0.94(95%confidence interval:0.8536-1.000)for the differential diagnosis of IPAS from PNET.Similarly,a cutoff value of 1.342 for normalized ADC was associated with 81.25%sensitivity,92.31%specificity,and 86.21%accuracy with an area under the curve of 0.91(95%confidence interval:0.8080-1.000)for the differential diagnosis of IPAS from PNET.Both methods showed excellent inter-reader reliability with intraclass correlation coefficients for absolute ADC and ADC ratio being 0.968 and 0.976,respectively.CONCLUSION Both absolute ADC and normalized ADC values can facilitate the differentiation between IPAS and PNET. 展开更多
关键词 PANCREAS Neuroendocrine tumors Accessory spleen Diffusion-weighted imaging Diagnostic performance
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光催化分解水制备氢气和过氧化氢(英文) 被引量:9
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作者 王利超 曹爽 +3 位作者 郭凯 吴志娇 马智 朴玲钰 《Chinese Journal of Catalysis》 SCIE EI CAS CSCD 北大核心 2019年第3期470-475,共6页
过氧化氢不仅是一种广泛应用于化学合成、消毒、废水处理及纸浆漂白等领域的高价值化学品,还是一种具有潜力的能源载体.此外,过氧化氢燃料电池因其结构简单而受到广泛关注.蒽醌法是工业生产过氧化氢的传统方法,但是这种方法不仅能耗高,... 过氧化氢不仅是一种广泛应用于化学合成、消毒、废水处理及纸浆漂白等领域的高价值化学品,还是一种具有潜力的能源载体.此外,过氧化氢燃料电池因其结构简单而受到广泛关注.蒽醌法是工业生产过氧化氢的传统方法,但是这种方法不仅能耗高,而且生产过程会造成严重的环境问题.因此,通过环保并且低成本的工艺直接合成过氧化氢具有重要研究意义.以太阳能为动力的光催化法生产过氧化氢被认为是最有前景的方法之一.目前,光催化已在制氢、二氧化碳还原和水处理等诸多领域取得了重要进展.但是,利用光催化分解水制备过氧化氢的研究还非常少.尽管通过光催化还原氧气可以制备过氧化氢,但是通过分解水同时制备高价值过氧化氢和氢气更具有吸引力.在本项工作中,我们利用Pt/TiO_2(锐钛矿)光催化剂在没有牺牲剂的条件下实现了高效产氢和过氧化氢,氢气和过氧化氢的生成速率分别达到7410和5096μmol g^(–1) h^(–1) (第一小时),远高于市售的Pt/TiO_2 (锐钛矿)体系和文献报道数值.本文采用X射线光电子能谱(XPS)、电子自旋共振(ESR)和荧光标记法等表征手段研究了Pt/TiO_2上同时生成氢气和过氧化氢的催化机理.XPS测试结果表明, Pt/TiO_2在光照射1 h后, XPS信号发生明显变化.与其他样品相比,物理吸附水和羟基的峰明显增加.因此,我们推测羟基和物理吸附水对过氧化氢的生成具有重要影响.进一步采用电子自旋共振(ESR)和荧光标记法对羟基进行了测量.ESR结果显示,紫外光照60 s即可检测到羟基捕获剂与羟基的结合物5,5-dimethyl-1-pyrroline-N-oxide-OH(DMPO-OH)的特征峰.此外,在体系中加入荧光标记分子对苯二甲酸(TANa)后也可以迅速检测到2-羟基对苯二甲酸(TAOH)在422 nm处明显的荧光信号.因此, ESR和荧光结果均表明所产生的羟基自由基在过氧化氢形成中起着重要作用.上述结果表明,在本体系中氢气和过氧化氢的生成遵循两电子转移过程.与传统全分解水体系生成氢气和氧气相比,两电子转移过程比四电子过程更容易发生.因此,光催化水氧化制过氧化氢是实现大规模生产氢气和过氧化氢的一种很有前景的方法. 展开更多
关键词 光催化分解水 氢气 过氧化氢 锐钛矿
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幼儿体力活动水平:基于幼儿身体活动观察记录系统的评估 被引量:4
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作者 郭凯 胡碧颖 陈月文 《学前教育研究》 CSSCI 北大核心 2022年第1期34-45,共12页
中高强度的体力活动与幼儿身体素质相关显著,幼儿园应保障幼儿每天有足够的中高强度体力活动。本研究运用幼儿身体活动观察记录系统,在广东省54所幼儿园开展幼儿体力活动水平调查。结果发现,幼儿的体力活动水平整体较低,久坐行为频率高... 中高强度的体力活动与幼儿身体素质相关显著,幼儿园应保障幼儿每天有足够的中高强度体力活动。本研究运用幼儿身体活动观察记录系统,在广东省54所幼儿园开展幼儿体力活动水平调查。结果发现,幼儿的体力活动水平整体较低,久坐行为频率高,中高强度活动频率低。不同活动类型和不同等级幼儿园在体力活动水平上差异显著,具体表现为:在平均体力活动水平方面,自由游戏与早操显著高于体育游戏,省一级、办园级显著高于市一级;在久坐行为频率方面,自由游戏显著低于早操和体育游戏,省一级显著低于市一级;在中高强度活动频率上,自由游戏显著高于体育游戏和早操,省一级显著高于市一级。幼师比偏高,生均活动面积和生均器材数量偏少,教师对户外活动中的运动安全和常规格外关注,专注于游戏情境创设,对运动量和强度关注太少,编制的早操活动结构不合理、基本体操不科学,是幼儿体力活动水平整体不高、幼儿在教师组织实施的体育游戏与早操中的体力活动水平反不如户外自由游戏的重要原因。为提高幼儿在园体力活动水平,幼儿园应合理分配户外活动类型比例,增加户外自由游戏时间;相关部门应提升教师体育素养,加强对幼儿园户外活动的专业评价与监督。 展开更多
关键词 体力活动 户外活动 身体活动观察记录系统
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Mo的引入方式对CeO_(2)脱硝性能的影响 被引量:2
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作者 李露露 葛成艳 +6 位作者 季稼伟 谭伟 王鑫 魏小倩 郭凯 汤常金 董林 《Chinese Journal of Catalysis》 SCIE EI CAS CSCD 2021年第9期1488-1499,共12页
固定源排放的氮氧化物(NOx)导致了严重的环境污染问题,NH_(3)选择性催化还原(NH_(3)-SCR)被认为是目前控制NOx排放的最有效技术,已广泛应用于电力行业的烟气排放治理.然而,我国非电行业的NOx减排仍然面临着重大挑战,因为其排放的废气温... 固定源排放的氮氧化物(NOx)导致了严重的环境污染问题,NH_(3)选择性催化还原(NH_(3)-SCR)被认为是目前控制NOx排放的最有效技术,已广泛应用于电力行业的烟气排放治理.然而,我国非电行业的NOx减排仍然面临着重大挑战,因为其排放的废气温度通常低于300℃,且含有一定量的SO_(2),传统的钒基SCR催化剂因活性温度(300~400℃)较高而无法有效发挥作用.因此,亟待开发新型的高效低温SCR催化剂.铈基催化剂由于氧化铈(CeO_(2))的优异储氧能力(OSC)和良好的氧化还原能力而显示出较好的低温(80~300℃)脱硝性能,如Mn-Ce,W-Ce,Ta-Ce,Cu-Ce和Nb-Ce等.但这些铈基催化剂易被烟气中的SO_(2)毒化而导致催化活性降低.因此,提高铈基SCR催化剂抗硫中毒能力是其产业化应用的关键.已有研究发现,通过构筑结构保护层或添加另一种金属来保护活性组分是提高SCR催化剂抗硫性能的一种可行策略.氧化钼(MoO3)通常被用做传统V_(2)O_(5)/TiO_(2)催化剂的促进剂以提高其水热稳定性和表面酸性.研究表明,在V/Ti催化剂中引入钼物种不仅可以提高其SCR活性,而且提高了V/Ti催化剂的抗SO_(2)性能,这是由于VMo/Ti表面较少的V‒O‒V键削弱了对SO_(2)的氧化作用.Tang等开发了一种Fe_(2)O_(3)/MoO3纳米片催化剂,显示出比纯Fe_(2)O_(3)更好的抗SO_(2)能力,主要是由于层状结构的MoO3能阻止NH4+在硫酸氢铵中的沉积.目前关于Mo的引入方式即催化剂的制备方法对铈基催化剂物化性能和NH_(3)-SCR催化性能(特别是抗SO_(2)能力)的影响的研究还比较少.本文分别采用浸渍法和沉淀法在CeO_(2)中引入钼物种,制备了Mo-CeO_(2)和MoCe-cp催化剂来探究制备方法对MoCe催化剂的脱硝性能及抗SO_(2)中毒能力的影响.结果表明,引入Mo可以显著地提高CeO_(2)的低温脱硝性能,其中Mo-CeO_(2)催化剂在150℃即可达到80%以上的脱硝效率,同时抗SO_(2)中毒性能也得到了显著提高.对催化剂结构、氧化还原能力、表面酸度和反应物分子的吸附脱附性质进行了表征,并与MoCe催化剂脱硝性能和抗硫性能相关联.结果表明,Mo-CeO_(2)和MoCe-cp催化剂的物理化学性质和脱硝性能有明显区别.首先,Mo-CeO_(2)中的钼物种主要存在于CeO_(2)表面,而MoCe-cp中的钼物种主要存在于CeO_(2)体相,其为Mo-CeO_(2)表面带来大量的Brönsted酸位并抑制了硝酸盐的吸附,促使NH_(3)-SCR反应按照Eley-Rideal机理进行,进而表现出优于MoCe-cp的低温活性.其次,Mo-CeO_(2)表面更多的Mo物种抑制了SO_(2)的吸附,从而使Mo-CeO_(2)表现出更好的抗SO_(2)性能.本文为具有实际应用前景的铈基NH_(3)-SCR催化剂的设计提供了参考. 展开更多
关键词 表面修饰 MoO3-CeO2 氨选择催化还原 Brönsted酸位 抗SO2中毒
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Conceptual design of an extractive distillation process for the separation of azeotropic mixture of n-butanol-isobutanol-water 被引量:5
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作者 Hengjun Gai kaiqiang Lin +3 位作者 Yirong Feng Meng Xiao kai guo Hongbing Song 《Chinese Journal of Chemical Engineering》 SCIE EI CAS CSCD 2018年第10期2040-2047,共8页
In many chemical processes, large amounts of wastewater containing butanol and isobutanol are produced.Given that n-butanol-isobutanol-water can form triple azeotrope, high-purity butanol cannot be recovered from the ... In many chemical processes, large amounts of wastewater containing butanol and isobutanol are produced.Given that n-butanol-isobutanol-water can form triple azeotrope, high-purity butanol cannot be recovered from the wastewater by ordinary distillation. To economically and effectively recover butanol from this kind of wastewater, 1,4-butanediol is selected as an extractant to break the formation of the azeotropes, and a doubleeffect extractive distillation process is proposed. The conceptual design of the proposed process is accomplished based on process simulation. With the proposed process, the purity of recovered butanol and water is greater than 99.99 wt%. In comparison with the conventional azeotropic distillation process, economic analysis shows that the operating cost of the proposed process is lower: when the capacity of wastewater treatment is 100 t·h^(-1), the total operating cost decreases by 5.385 ×10~6 USD per year, and the total annual cost of the new process decreases by 5.249 ×10~6 USD per year. In addition, in the extractive distillation system, variable effects on separation purities and cost are more complex than those in the ordinary distillation system. The method and steps to optimize the key variables of the extractive distillation system are also discussed in this paper and can provide reference for similar studies. 展开更多
关键词 共沸混合物 蒸馏过程 设计 分离 废水处理 操作费用 蒸馏系统 经济分析
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碱金属阳离子对铁卟啉电催化CO_(2)还原的影响
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作者 郭凯 雷海涛 +5 位作者 李夏亮 张宗尧 王亚博 郭鸿波 张伟 曹睿 《Chinese Journal of Catalysis》 SCIE EI CAS CSCD 2021年第9期1439-1444,共6页
电催化CO_(2)还原反应(CO_(2)RR)可以有效地将温室气体转化为燃料或高附加值的化学品,从而缓解目前人类所面临的环境问题和能源危机,其中开发高效的电催化剂是至关重要的环节.近年来,研究者设计了多种高效的过渡金属配合物(包括Mn,Fe,Co... 电催化CO_(2)还原反应(CO_(2)RR)可以有效地将温室气体转化为燃料或高附加值的化学品,从而缓解目前人类所面临的环境问题和能源危机,其中开发高效的电催化剂是至关重要的环节.近年来,研究者设计了多种高效的过渡金属配合物(包括Mn,Fe,Co,Ni和Cu)用作CO_(2)RR分子电催化剂,并研究了其中的构效关系,例如,在分子内修饰质子给体取代基或电荷取代基可以显著提高CO_(2)RR的催化效率.而电催化CO_(2)RR的实际应用要在含有碱金属阳离子(例如,Na^(+)和K^(+))的电解质水溶液中进行,但在已有报道中,很少有关于碱金属阳离子对CO_(2)RR的影响.在众多的分子催化剂中,铁卟啉可以以较高的催化活性和选择性实现CO_(2)到CO的转化.重要的是,卟啉环的刚性结构、稳定的配位环境及其骨架上官能团的易于修饰性成为研究CO_(2)RR的构效关系的理想分子模型.基于以上考虑,本文以铁卟啉配合物为分子模型,研究了碱金属阳离子Na^(+)和K^(+)对电催化CO_(2)RR的影响.首先,本文合成了简单的A4型铁卟啉化合物四-(3,4,5-三甲氧基苯基)-铁卟啉(FeP).并采用核磁共振、质谱分析、单晶衍射等表征手段对化合物进行了表征,在含有电解质的DMF溶液中测试其电催化CO_(2)还原性能.实验结果表明,FeP可以实现高效的电催化CO_(2)还原,催化电流随FeP的浓度呈线性增加,说明催化反应速率与催化剂浓度呈一级反应速率关系.较长时间的恒电压电解实验以及电解前后化合物的紫外-可见光谱证实了FeP的稳定性.通过气相色谱对产物进行分析,CO为主要产物,法拉第效率为95%.以上结果均表明,FeP是一个优良的分子催化剂.在此基础上,本文还发现加入Na^(+)和K^(+)均可以显著提升催化活性,而K^(+)的加入使催化电流的提升更加显著,这可能是由于K^(+)在溶液中的迁移速度比Na^(+)更快.基于此实验现象,本文通过在FeP的第二配位层修饰1-氨-18-冠-6-醚官能团(^(N)18C6),合成了^(N)18C6-FeP化合物.结果表明,由于^(N)18C6与Na^(+)/K^(+)之间的配位作用,使得^(N)18C6-FeP比FeP具有更好的电催化CO_(2)RR活性.研究表明,催化活性的提升归因于碱金属阳离子能够通过静电相互作用稳定Fe-CO_(2)中间体.1H NMR谱证实了^(N)18C6基团的确能够螯合碱金属阳离子.本文研究证明了碱金属阳离子对改善电催化CO_(2)RR的积极作用,对于进一步深入了解CO_(2)RR催化反应机理和未来合理的设计高效催化剂也都具有重要意义. 展开更多
关键词 二氧化碳还原 分子电催化 碱性金属阳离子效应 铁卟啉 构效关系
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胍基铁卟啉显著提高了水溶液中电催化二氧化碳还原的活性和选择性
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作者 郭鸿波 梁作中 +4 位作者 郭凯 雷海涛 王亚博 张伟 曹睿 《Chinese Journal of Catalysis》 SCIE EI CAS CSCD 2022年第12期3089-3094,共6页
电催化CO_(2)还原反应(CO_(2)RR)可以制造燃料和增值化学品,为使用化石燃料带来的相关问题提供了理想的解决策略,因此,开发具有高效率、高选择性的CO_(2)RR电催化剂引起了人们的广泛关注.最近的研究表明,第一过渡金属配合物包括Mn,Fe,Co... 电催化CO_(2)还原反应(CO_(2)RR)可以制造燃料和增值化学品,为使用化石燃料带来的相关问题提供了理想的解决策略,因此,开发具有高效率、高选择性的CO_(2)RR电催化剂引起了人们的广泛关注.最近的研究表明,第一过渡金属配合物包括Mn,Fe,Co,Ni和Cu,均可作为CO_(2)RR电催化剂.在众多配合物中,铁卟啉化合物是研究结构-功能关系的理想模型复合物之一,因为卟啉大环化合物可以为中心金属离子提供强大而稳定的配位环境,并且可以通过引入各种官能团进行系统修饰,同时也因其在非水溶液中可以高效地催化CO_(2)转化为CO的而备受关注.然而,与非水溶液体系不同,铁卟啉在水溶液中CO_(2)RR表现出较差或中等的选择性,其原因在于当使用水作为反应介质时,竞争性析氢反应会变得严重.众所周知,使用水作为电催化反应溶剂,不仅绿色环保,而且可以充分提供二氧化碳还原过程中所需的质子.因此,开发水溶剂中铁卟啉CO_(2)RR电催化剂,使其在水溶液中表现出高活性高选择性具有重要的现实意义.本文设计并合成了带有胍基的铁卟啉化合物1以及简单的A4型铁卟啉化合物2,利用核磁共振、质谱分析等手段对化合物进行了表征,研究了两种化合物在非水溶液(均相电催化)和水溶液(多相电催化)中对CO_(2)RR的电催化性质.在乙腈溶液中,铁卟啉1及铁卟啉2均能有效地将CO_(2)转化为CO,转化频率表现为1(3.9×10^(5)s^(-1))比2(1.7×10^(4)s^(-1))大一个数量级,表明了胍基在提高电催化CO_(2)RR活性方面的关键作用.更重要的是,胍基具有生物相容性,可以在pH≤7的水溶液中被质子化,因此将化合物负载在碳纳米管(CNTs)上,研究其在0.1 mol L^(-1)KHCO_(3)水溶液中催化CO_(2)RR活性,结果表明,1/CNT显示出非常高的电催化CO_(2)-CO转化选择性,法拉第效率为96%,而2/CNT仅为65%,同时1/CNT在水溶液中长时间电解的CO_(2)RR电催化效率仍然优于2/CNT.综上,本文研究结果表明胍基对提高铁卟啉CO_(2)RR电催化的活性和选择性具有重要意义. 展开更多
关键词 CO_(2)还原 分子电催化 铁卟啉 静电相互作用 质子转移
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Hydrodynamics and bubble behaviour in a three-phase two-stage internal loop airlift reactor 被引量:3
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作者 Dan Li kai guo +4 位作者 Jingnan Li Yiping Huang Junchao Zhou Hui Liu Chunjiang Liu 《Chinese Journal of Chemical Engineering》 SCIE EI CAS CSCD 2018年第6期1359-1369,共11页
Local hydrodynamics of a gas–liquid–solid system,such as bubble circulation regime,gas holdup,liquid velocity and axial profile of solid concentration,are studied in a two-stage internal loop airlift reactor.Empiric... Local hydrodynamics of a gas–liquid–solid system,such as bubble circulation regime,gas holdup,liquid velocity and axial profile of solid concentration,are studied in a two-stage internal loop airlift reactor.Empirical correlations for gas holdup and liquid velocity are proposed to ease the reactor design and scale-up.Different bubble circulation regimes were displayed in the first(lower) and second(upper) stages.Increasing superficial gas velocity and solid loading can promote regime transition of the second stage,and the gas holdup of the second stage is higher than that of the lower stage.In addition,the effects of solid loading on bubble behaviour are experimentally investigated for each stage.It is found that bubble size in the downcomer decreases with the presence of solid particles,and bubble size distribution widens under higher superficial gas velocity and lower solid loading. 展开更多
关键词 反应堆设计 水动力学 水泡 空运 二阶 液体速度 行为 三阶
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Low-cost preparation of mesoporous silica with high pore volume 被引量:4
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作者 Shuling Shen Wei Wu +1 位作者 kai guo Jianfeng Chen 《Journal of University of Science and Technology Beijing》 CSCD 2007年第4期369-372,共4页
Mesoporous silica materials with high pore volume were successfully prepared by the chemical precipitation method, with water glass and a biodegradable nonionic surfactant polyethylene glycol (PEG). The obtained mater... Mesoporous silica materials with high pore volume were successfully prepared by the chemical precipitation method, with water glass and a biodegradable nonionic surfactant polyethylene glycol (PEG). The obtained materials were characterized by trans-mission electron microscopy (TEM), scanning electron microscopy (SEM), thermo gravimetric analyzer and differential scanning calorimetry (TG-DSC), nitrogen adsorption-desorption measurements, and X-ray diffraction (XRD). The results showed that the changes of the pore parameters depended on both the surfactant content and heat treatment temperature. When the content of PEG was 10wt/ and the obtained PEG/SiO2 composite was heated at 600°C, the mesoporous silica with a pore volume of 2.2 cm3/g, a BET specific surface area of 361.55 m2/g, and a diameter of 2-4 μm could be obtained. The obtained mesoporous silica materials have po-tential applications in the fields of paint and plastic, as thickening, reinforcing, and flatting agents. 展开更多
关键词 二氧化硅 化学沉淀 高孔隙体积 水玻璃杯 非离子物质表面活性剂
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High powerλ~8.5μm quantum cascade laser grown by MOCVD operating continuous-wave up to 408 K 被引量:3
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作者 Teng Fei Shenqiang Zhai +10 位作者 Jinchuan Zhang Ning Zhuo Junqi Liu Lijun Wang Shuman Liu Zhiwei Jia Kun Li Yongqiang Sun kai guo Fengqi Liu Zhanguo Wang 《Journal of Semiconductors》 EI CAS CSCD 2021年第11期55-60,共6页
Robust quantum cascade laser(QCL)enduring high temperature continuous-wave(CW)operation is of critical importance for some applications.We report on the realization of lattice-matched InGaAs/InAlAs/InP QCL materials g... Robust quantum cascade laser(QCL)enduring high temperature continuous-wave(CW)operation is of critical importance for some applications.We report on the realization of lattice-matched InGaAs/InAlAs/InP QCL materials grown by metal-organic chemical vapor deposition(MOCVD).High interface quality structures designed for light emission at 8.5μm are achieved by optimizing and precise controlling of growth conditions.A CW output power of 1.04 W at 288 K was obtained from a 4 mm-long and 10μm-wide coated laser.Corresponding maximum wall-plug efficiency and threshold current density were 7.1%and 1.18 kA/cm2,respectively.The device can operate in CW mode up to 408 K with an output power of 160 mW. 展开更多
关键词 quantum cascade laser metal-organic chemical vapor deposition CONTINUOUS-WAVE interface roughness
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