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21篇 您的检索式:作者名="Yuechen Li"
    题名 作者 年代 出处 被引量
1Developing land use scenario dynamics model by the integration of system dynamics model and cellular automata model显示文摘Modeling land use scenario changes and its potential impacts on the structure and function of the ecosystem in the typical regions are helpful to understanding the interactive mechanism between land use system and ecological system. A Land Use Scenario Dynamics (LUSD) model by the integration of System Dynamics (SD) model and Cellular Automata (CA) model is developed with land use scenario changes in northern China in the next 20 years simulated in this paper. The basic idea of LUSD model is to simulate the land use scenario de-mands by using SD model at first, then allocate the land use scenario patterns at the local scale with the considerations of land use suitability, inheritance ability and neighborhood effect by using CA model to satisfy the balance between land use scenario demands and supply. The application of LUSD model in northern China suggests that the model has the ability to reflect the complex behavior of land use system at different scales to some extent and is a useful tool for assessing the potential impacts of land use system on ecological system. In addition, the simulated results also indicate that obvious land use changes will take place in the farming-pastoral zone of northern China in the next 20 years with cultivated land and urban land being the most active land use types.HE Chunyang, SHI Peijun, CHEN Jin, Li Xiaobing, PAN Yaozhong, LI Jing, LI Yuechen & LI Jinggang Key Laboratory of Environmental Change and Natural Disaster, Ministry of Education of China, Beijing Normal University College of Resources Science & Technology, Beijing Normal University, Beijing 100875, China 2005Science China Earth Sciences2005,48,11:21
2Evaluation on the human settlements environment suitability in the Three Gorges Reservoir Area of Chongqing based on RS and GIS显示文摘为了在量的特征和人的解决的空间模式探索地理差别,在三的环境适用性( HSES )塞满水库区域( TGRA ),地面,气候,水文学,植被和另外的天赋因素被选择造过得去的环境评估,并且定量分析通过遥感( RS )和地理参考系统( GIS )被进行揭示地理特征和 HSES 的空间模式。结果如下被获得:(1 ) 重庆的 TGRA 的居民与中等高 HSES 在区域被集中,它是在 48% 学习区域散布的 78% 全部的人口;(2 ) HSES 是仔细与地面有关,并且它形成一个弧乐队空间继任模式:在东北和东南相对低当时在西方和南方比较地高;(3 ) 大量人与低适用性在区域被散布(与更高的人口密度比西方的中国的一般水准) ,但是在这些区域的经济发展水平是相当低的。而且,这些区域是生态的敏感、易碎,许多种 eco 环境的问题被人的活动引起了。因此,人口移植和布局是为这些区域的发展的合理选择。LI Yuechen 2011Journal of Geographical Sciences2011,21,2:12
3Land cover dynamic changes in northern China: 1989-2003显示文摘The 13 provinces (autonomous regions and municipalities) in northern China are located in latitude 31°–54°N and longitude 73°–136°E including Beijing, Tianjin, Hebei, Shanxi, Inner Mongolia, Jilin, Liaoning, Heilongjiang, Shaanxi, Gansu, Ningxia, Qinghai, and Xinjiang, where environments are fragile. In recent years, the eco-environmental problems such as vegetation destruction, desertification and soil erosion etc. become serious because of climate change and unreasonable human activities. In this paper, landscape pattern and its evolution in northern China from 1989 to 2003 was investigated by the combined use of RS and GIS based on the basic theory and method of landscape ecology. Land use/cover maps of the study area in 1989, 1999 and 2003 were produced by using 1 km monthly NOAA Ad- vanced Very High Resolution Radiometer (AVHRR) and SPOT/VGT Normalized Difference Vegetation Index (NDVI) dataset from national climate bureau of China which were geo-registered to Lambert azimuthal equal-area map projection and were used in the paper. Landscape evolution in the area over the study period was investigated by two methods: (a) the changes of various landscape metrics were analyzed using the landscape structure analysis program FRAGSTATS; (b) the transition matrix of landscape patch types was cal- culated with the help of the RS and GIS software. The results showed that from 1989 to 2003, the landscape within the study area had undertaken a complicated evolution in landscape structure and composition. The diversity index and evenness index increased during the pe- riod, which means that the landscape pattern tended to be diversified and even. The frag- mentation index of grassland, forestland and water areas also increased significantly. This showed that the distribution and structure of forestland, grassland and water areas had been changed greatly during the period, especially grassland which became more and more fragmentized, and its fragmentation index increased from 19.23% to 88.72%. The transitions of the landscape types were mainly shown by the changes among forestland, grassland and farmland, and grassland changing into unable land. Over the study period, grassland and water areas had decreased remarkably, accounting for 15% and 37% from 1989 to 1999 and 24.79% and 49.25% from 1999 to 2003 respectively. The grassland and water resources play an important role in the eco-environment and economic development of the region. So, they must be protected carefully. According to the analysis, we can conclude that the eco-environment in the study area is obviously degenerated due to unreasonable human activities and climate changes and some measures should be taken to combat the environ- mental degradation.LI Yuechen 2008Journal of Geographical Sciences2008,18,1:10
4IL-37b suppresses T cell priming by modulating dendritic cell maturation and cytokine production via dampening ERK/NF-κB/S6K signalings显示文摘Interleukin 37b (IL-37b ) 在压制有免疫力的回答起一个关键作用,部分由 modulating 树枝状的房间(DC ) 的功能。然而,精确机制大部分仍然是未知的。这里,我们在回答由 DC 导致了的 DC 成熟和 T 房间上调查了 IL-37b 的效果,并且探索了深奥发信号的小径。它被发现那 IL-37b 下面调整在 vitro 的 DC 上的 co-stimulatory 分子 CD80 和 CD86 的表情。同时,支持 inflammatory cytokines 的表情例如 TNF-6, 和 IL-6,被压制,当时 T 房间的表示禁止的 cytokine TGF- 在 IL-37b-treated DC 被增加。另外, T 房间上的 DC 的激活效果被 IL-37b 损害。我们进一步表明细胞外的调整单人赛的 kinase (英皇家空军之阶级最低之兵) ,原子 factor-B (NF-B ) ,和表明小径的 mTOR-S6K 涉及 IL-37b 导致的 DC 的抑制。这被化学禁止者的同样镇压的效果在 DC 在 IL-6 和 TNF- 的表情上对 NF-B,英皇家空军之阶级最低之兵,和 S6K 证实。在结论,这些结果证明 IL-37b 由在英皇家空军之阶级最低之兵, NF-B,和基于 S6K 的禁止的发信号小径包含在 T 房间 priming 压制了 DC 成熟和 immunostimulatory 能力。Wantong Wu Weiqiang Wang Yun Wang Wenwen Li Gang Yu Zhonglong Li Chunmin Fang Yue Shen Zhina Sun Ling Han Juan Yu Lijun Fang Song Chen Kui Dong Zhongchao Han Hanzhi Liu Yuechen Luo Xiaoming Feng 2015Acta Biochimica et Biophysica Sinica2015,47,8:8
5Scenario simulation and forecast of land use/cover in northern China显示文摘Modeling land use/cover scenario changes and its potential impacts on structure and functions of ecosystem in typical regions are helpful to understanding the interactive mechanism between land use/cover system and ecosystem. Based on the analysis of the existing land use/cover simulation and forecast models, a land use/cover scenario dynamics model by the integration of System Dynamics (SD) model, Back Propagation Neural Network (BPNN) and Cellular Automata (CA) model is developed with land use/cover scenario changes in northern China in the next 30 years and simulated in this paper. The model is to simulate the land use/cover scenario demands by using a SD model at first, and then allocating the land use scenario patterns at the local scale with the considerations of land use/cover suitability, inheritance ability and neighborhood effect by using BPNN-CA model to satisfy the balance between land use/cover scenario demands and supplies. It integrates the advantages of SD, BPNN and CA. Macro-driving factors and the micro-spatial pattern are also fully taken into account. The BPNN simplifies the identification of the factors’ weights used in CA model and improves the reliability of the simulation results. The simulation accuracy of the model developed in this paper was found to be about 74%. It suggests that the model has the ability to reflect the complexity of land use/cover system at different scales to some extent and it is a useful tool for assessing the potential impacts of land use system on ecosystem. The simulated results also indicate that the urban land, water area and forest will increase significantly, and farmland and unable land will decrease gradually. Obvious land use/cover changes will take place in the farming-pastoral zone and the southeast area of northern China.LI YueChen 1,2,3 & HE ChunYang 3 1 College of Geographical Science, Chongqing Normal University, Chongqing 400047, China 2 College of Resources and Environmental Science, Chongqing University, Chongqing 400044, China 3 College of Resources Science & Technology, Beijing Normal University, Beijing 100875, China 2008Chinese Science Bulletin2008,53,9:6
6Urban Green Space, Uneven Development and Accessibility: A Case of Dalian′s Xigang District显示文摘This study examines the socio-spatial context of uneven development and the residential accessibility of green space in Dalian of Liaoning Province, China. The social fairness was analyzed with a community scale as the basis. We combined social scientific methods with a GIS method using a behavior accessibility model from the perspectives of fairness of urban green space allocation based on social geography, geographic information science, management science and many other related discipline theories. The results show that: 1) Most of the urban green space distribution presents an unbalanced phenomenon, and it does not match with the population distribution; 2) We found some differences in the accessibility of the population with different attributes and opportunities to use and enjoy the urban green spaces, mainly due to: the dual social and spatial attributes of the residents and the serious stratum differentiation generated were the internal causes; the residential space differentiation and the pursuit of economic and real estate development were the direct causes; and unreasonable planning, in regard to the fact that government policies did not give consideration to efficiency and fairness, was also an important factor.YANG Jun LI Chuang LI Yuechen XI Jianhao GE Quansheng LI Xueming 2015Chinese Geographical Science2015,25,5:3
7Short-term intermittent administration of CXCR4 antagonist AMD3100 facilitates myocardial repair in experimental myocardial infarction显示文摘stromal 的绑定导出房间的 factor-1 (SDF-1 ) 到半胱氨酸(C)-X-C 主题 chemokine 受体(CXCR4 ) 4 从骨头髓为茎和祖先房间 trafficking 作为一个关键信号出现了到发行量。我们的目的是在心肌的梗塞(MI ) 以后在愈合的过程期间调查 AMD3100 (一个特定的可逆 CXCR4 受体对手) 的每日的断断续续的管理的角色。Wistar 老鼠受到 MI, AMD3100 在外科以后 intraperitoneally 被注射。SDF-1 mRNA 表示被即时聚合酶链反应测量。组织学变化与 immunofluorescence 被分析,马森的三色的染色,并且小麦细菌凝集素。在外部血的白血球的数字被完全的血房间计数分析测量。矩阵 metalloproteinase-2/9 (MMP-2/9 ) 的活动被明胶 zymography 决定。在 infarcted 织物的 SDF-1 mRNA 的表示水平很快被提高(6 h ) ,在 24 h 达到顶点,然后在 7 天 post-MI 衰退了到正常水平。AMD3100 进一步在梗塞区域提高了 SDF-1 的增加。增加的白血球在对待 AMD3100 的组被观察。c-kit+ 干细胞和提高的 neovascularization 的动员被 AMD3100 扩充。另外, AMD3100 改进了室的改变,它被梗塞尺寸的减少揭示,可行 cardiomyocyte 代表性的区域和左室(LV ) LV 免费的墙厚度的扩大索引,和增加。MMP-2/9 的活动由 AMD3100 是起来调整的。在结论, AMD3100 的短期的断断续续的管理能在试验性的 MI 加速弯屈的愈合的过程并且是为 MI 的处理的潜在的治疗。Yuechen Luo Xiaoning Zhao Xin Zhou Wenjie Ji Ling Zhang Tao Luo Hongmei Liu Tigang Huang Tiemin Jiang Yuming Li 2013Acta Biochimica et Biophysica Sinica2013,45,7:3
8The Estimation and Control of the Electroslag Remelting Melt Rate by Mechanism-Based Modeling显示文摘Wanzhou Li Weiyu Wang Yuechen Hu Yixing Chen 2012Metallurgical and Materials Transactions B2012,,2:1
9Performance analysis of SBAS ephemeris corrections and integrity algorithms in China region显示文摘Satellite Based Augmentation Systems(SBASs)improve the positioning accuracy and integrity by broadcasting to the civil aviation community the corrections and integrity parameters.A snapshot algorithm based on the minimum variance estimation is investigated in this study to calculate the satellite clock and orbit corrections.A chi-square test is performed on the remaining errors in the corrected ephemeris to guarantee the integrity.User Differential Range Error(UDRE)and scaling matrix contained in Message Type 28 are derived using the covariance information based on the assumption that one of the reference stations failed.A software package is developed and applied in the real data collected at 26 stations.International GNSS(Global Navigation Satellite System)Service(IGS)precise clock and orbit products are taken as the references to assess the accuracy of corrections.For both Global Positioning System(GPS)and BeiDou Navigation Satellite System(BDS),the range accuracy of 0.10 m can be achieved with the employment of the derived corrections.No obvious performance difference between GPS and BDS is found.UDREs for all visible satellites are generated with the maximum index of 12 and minimum index of 3.The geometric range differences calculated with IGS precise products and broadcast ephemeris are employed to assess the integrity of UDRE.It is found that the UDRE is able to bound the residuals with 99.9%confidence which meet the requirement of aviation users.With ionospheric delay corrected by Global Ionosphere Map(GIM),the positioning accuracy of 0.98 m with GPS corrections and 0.80 m with multi-constellation augmentation can be achieved which indicates a significant improvement of GPS standalone results.Biao Jin Shanshan Chen Dongjun Li Yuechen Wang Elhadi Takka 2021Satellite Navigation2021,2,1:1
10Research of Signal-in-Space Integrity Monitoring Based on Inter-satellite Links显示文摘Using the Inter-satellite links(ISLs) to enhance the GNSS's positioning accuracy and integrity is attracting much more attentions. In order to ensure the autonomous positioning accuracy and stability based on ISLs, a satellite and ground joint positioning mode is presented in this paper, which is constrained by quality grade of position error. Spatial error ellipsoid is applied to calculate parameters and achieve Signal-in-space(SIS) integrity monitoring. To check the accuracy of the mode and performance of monitoring, mixed constellation of Beidou system is simulated to support the analysis and investigate the impact of the high-low ISLs. The orbit determination results verify that the introduced integrity monitoring method can satisfy the integrity risk of 10-5/h and achieve the SIS integrity monitoring.WANG Yuechen LI Rui ZHAO Ruibin 2015Chinese Journal of Electronics2015,24,2:1
11Responses of photosynthetic characteristics and enzyme activity of nitrogen metabolism to low nitrogen in maize with different nitrogen tolerance显示文摘Understanding the physiological processes associated with leaf photosynthetic characteristics and nitrogen(N)assimilation during grain-filling stage are helpful for enhancing nitrogen utilization efficiency(NUtE)of maize.In this study,the leaf photosynthetic and N assimilation parameters in maize,including Zhengdan 958(ZD958),a low-N tolerance cultivar and Huanong 138(HN138),a low-N sensitive cultivar under different N rates were examined.Results showed that ZD958 displayed significant increases on grain yield and NUtE than that in HN138.Analyses on the leaf photosynthetic and N assimilation-associated processes indicated that ZD958 had higher leaf N remobilization(Rem N),net photosynthetic rate(Pn)and photosynthetic N use efficiency(PNUE)with respect to those of HN138 during grain-filling stage.In addition,ZD958 was also shown to be higher activities of leaf nitrate reductase(NR),glutamine synthetase(GS),nitrate reductase(GDH)and glutamine synthetase(GAGOT)than those of HN138.The leaf PNUE was significantly positively correlated with NR,GS,GDH,GOGAT suggesting that leaf PNUE and NR,GS,GDH,GOGAT jointly determined the N remobilization efficiency and the leaf N remobilization during post-silking.These results suggested that ZD958 possessed improved PNUE,NR and GS activities in leaves during grain-filling stage that contributes improve grain weights and yield formation capacities upon under low-N conditions.Pengtao Ji Yongwei Cui Xiangling Li Kai Xiao Peijun Tao Yuechen Zhang 2020International Journal of Agricultural and Biological Engineering2020,13,6:1
12Estimation of the PM_(2.5) effective hygroscopic parameter and water content based on particle chemical composition: Methodology and case study显示文摘Particle hygroscopicity plays a key role in understanding the mechanisms of haze formation and particle optical properties. The present study developed a method for predicting the effective hygroscopic parameter k and the water content of PM_(2.5) on the basis of the k-K?hler theory and bulk chemical components of PM_(2.5). Our study demonstrated that the effective hygroscopic parameter can be estimated using the PM_(2.5) mass concentration, water-soluble ions, and total water-soluble carbon. By combining the estimated k and ambient relative humidity, the water content of PM_(2.5) can be further estimated. As an example, the k and water content of PM_(2.5) in Beijing were estimated utilizing the method proposed in this study. The annual average value of k of PM_(2.5) in Beijing was 0.25±0.09, the maximum k value 0.26±0.08 appeared in summer, and the seasonal variation is insignificant. The PM_(2.5) water content was determined by both the PM_(2.5) hygroscopicity and the ambient relative humidity(RH). The annual average mass ratio of water content and PM_(2.5) was 0.18±0.20, and the maximum value 0.31±0.25 appeared in summer. Based on the estimated water content of PM_(2.5) in Beijing, the relationship between the PM_(2.5) water content and RH was parameterized as: m(%)=0.03+(5.73×10^(-8)) ×RH^(3.72).This parametric formula helps to characterize the relationship between the PM_(2.5) mass concentration and atmospheric visibility.LIU YueChen WU ZhiJun TAN TianYi WANG YuJue QIN YanHong ZHENG Jing LI MengRen HU Min 2016Science China Earth Sciences2016,59,8:1
13Zoning grassland protection area using remote sensing and cellular automata modeling-a case study in Xilingol steppe grassland in northern China显示文摘Chunyang He Qiaofeng Zhang Yuechen Li 2005Journal of Arid Environment2005,63,4:1
14Probing Filters to Interpret CNN Semantic Configurations by Occlusion显示文摘Deep neural networks has beenwidely used inmany fields,but there are growing concerns about its black-box nature.Previous interpretability studies provide four types of explanations including logical rules,revealing hidden semantics,sensitivity analysis,and providing examples as prototypes.In this paper,an interpretability method is proposed for revealing semantic representations at hidden layers of CNNs through lightweight annotation by occluding.First,visual semantic configurations are defined for a certain class.Then candidate filters whose activations are related to these specified visual semantics are probed by occluding.Finally,lightweight occlusion annotation and a scoring mechanism is used to screen out the filters that recognize these semantics.The method is applied to the datasets of mechanical equipment,animals and clothing images.The proposed method performs well in the experiments assessing interpretability qualitatively and quantitatively.Qian Hong Yue Wang Huan Li Yuechen Zhao Weiyu Guo Xiuli Wang 2021国际计算机前沿大会会议论文集2021,,2:0
15Ultrafast growth of wafer-scale fold-free bilayer graphene显示文摘Bilayer graphene provides a versatile platform for exploring a variety of intriguing phenomena and shows much promise for applications in electronics,optoelectronics,etc.Controlled growth of large-area bilayer graphene is therefore highly desired yet still suffers from a slow growth rate and poor layer uniformity.Meanwhile,graphene wrinkles,including folds and ripples,form during cooling due to the thermal contraction mismatch between graphene and the metal substrates,and have been far from suppressed or eliminated,especially in bilayer graphene,which would greatly degrade the extraordinary properties of graphene.Here we report the ultrafast growth of wafer-scale fold-free bilayer graphene by chemical vapor deposition.Through well-tuning the alloy thickness and strain regulation of the single-crystal CuNi(111)/sapphire,the full coverage of a 2-inch fold-free bilayer graphene wafer via mainly isothermal segregation has been achieved as fast as 30 s.The tensile-strained CuNi(111)film reduces the thermal contraction mismatch and suppresses the formation of graphene folds during cooling,which is directly observed through in situ optical microscopy.The ultraflat bilayer graphene exhibits wafer-scale uniformity in electrical performance and enhanced mechanical property comparable to the exfoliated ones.Our results offer a promising route for largescale production of bilayer graphene and enable its various applications.Jilin Tang Yuechen Wang Yuwei Ma Xiaoyin Gao Xin Gao Ning Li Yani Wang Shishu Zhang Liming Zheng Bing Deng Rui Yan Yisen Cao Ronghua Zhang Lianming Tong Jin Zhang Peng Gao Zhongfan Liu Xiaoding Wei Hongtao Liu Hailin Peng 2023Nano Research2023,16,7:0
16Micropascal-sensitivity ultrasound sensors based on optical microcavities显示文摘Whispering gallery mode(WGM)microcavities have been widely used for high-sensitivity ultrasound detection,owing to their optical and mechanical dual-resonance enhanced sensitivity.The ultrasound sensitivity of the cavity optomechanical system is fundamentally limited by thermal noise.In this work,we theoretically and experimentally investigate the thermal-noise-limited sensitivity of a WGM microdisk ultrasound sensor and optimize the sensitivity by varying the radius and a thickness of the microdisk,as well as using a trench structure around the disk.Utilizing a microdisk with a radius of 300μm and thickness of 2μm,we achieve a peak sensitivity of 1.18μPa Hz^(-1/2)at 82.6 k Hz.To the best of our knowledge,this represents the record sensitivity among cavity optomechanical ultrasound sensors.Such high sensitivity has the potential to improve the detection range of air-coupled ultrasound sensing technology.HAO YANG XUENING CAO ZHI-GANG HU YIMENG GAO YUECHEN LEI MIN WANG ZHANCHUN ZUO XIULAI XU BEI-BEI LI 2023Photonics Research2023,11,7:0
17Effects of reducing and postponing controlled-release urea application on soil nitrogen regulation and maize grain yield显示文摘Controlled-release urea(CRU-N)fertilizer application is a solution to improve the utilization rate of nitrogen(N),reduces economic costs and improves crop yields.It is significant to study the effects of release CRU-N reduction and the combined application of conventional urea on soil N control and the large-scale maize planting system.In this study,the effects of controlled-release nitrogen fertilizer reduction and postponement on soil nitrogen components,enzyme activities,and yields were investigated.Seven treatments were set up in this study,including no N fertilizer(CK),100%conventional urea(U),100%controlled-release urea(S),30%controlled-release urea(SU_(3/7)),50%controlled-release urea(SU_(5/5)),70%controlled-release urea(SU_(7/3))and Sodium Salt of Polyaspartic Acid(PASP)-N.The results showed that mixed CRU-N and urea increased yields and net benefits compared with conventional urea at the same application rate of N,and reduced N loss.The application of CRU-N at 70%for maize represented the best overall effects.Compared with U treatment,soil ammonium nitrogen(NH_(4)-N),soil nitrate-nitrogen(NO_(3)-N),and microbial biomass nitrogen(SMB-N)of CRU-N at 70%(SU_(7/3))increased by 35.00%,15.53%,and 25.04%.However,soil nitrate reductase(S-NR)and urease(S-UA)were the best in SU_(5/5) and significantly higher than other treatments.The applications of CRU-N would effectively increase soil N;CRU-N in 50%proportion can promote the maize root growth and improve the efficient utilization of N by soil microorganisms.Like the yields(9186.61 kg/hm^(2)),expertly in the proportion of 70%CRU-N(SU_(7/3))plays a vital role in a wheat-maize rotation system,which can potentially be used to improve the yields,nitrogen use efficiency,and net benefit with low N losses.In conclusion,using CRU-N fertilize effectively improves soil nitrogen,and various ratios of CRU-N can ensure the continuous release the nutrients during the growing period.And among the different proportions of CRU-N,it is optimal in SU_(7/3).Pengtao Ji Yujuan Peng Yongwei Cui Xiangling Li Peijun Tao Yuechen Zhang 2022International Journal of Agricultural and Biological Engineering2022,15,1:0
18Optimal feedback based control for Mars entry trajectory tracking显示文摘The various uncertainties of Mars environment have great impact on the process of vehicles entering the atmosphere.To improve the robustness of control system against the model errors and to reduce the computational burden, an optimal feedback based tracking control law is developed. The control scheme presented in this paper determines the amplitude and the reversals of bank angle respectively in the longitudinal and lateral flight plane. At each control cycle, the amplitude of the bank angle is obtained by an optimal feedback controller to minimize tracking errors. The control gains are tuned according to the closed-loop error dynamics by using optimization methods. The bank reversals are executed if the crossrange exceeds a predetermined corridor which is designed by setting a boundary function. The accuracy and robustness of the proposed closed-loop optimal feedback based control law in tracking the reference trajectory is verified via500 deviation simulations, in which modeling errors and external disturbances are considered.HUANG Yuechen LI Haiyang SHEN Hongxin 2018Journal of Systems Engineering and Electronics2018,29,1:0
19Tuning the formation of��β-phase poly(9,9-di-n-octylfluorenyl-2,7-diyl)via nano-confinement and polystyrene blending for improved photocatalysis显示文摘Among all the phase morphologies of poly(9,9-di-n-octylfluorenyl-2,7-diyl)(PFO),the��phase exhibits a zigzag coplanar arrangement with the highest conjugation degree.As a result,the��-phasePFO has extraordinary prop-erties,including enhanced charge carrier mobility.In this work,we report the formation of high-��-phase PFO in nanoparticles(NPs)due to the synergistic effect of the slow crystallization of PFO in nanodroplet confinement and polystyrene(PS)blending.The��-phase content of PFO can be flexibly tuned by varying the NP size,molec-ular weight(M w),or relative PS content in the NPs.The novel systems demonstrated in this study are likely to provide valuable insights into the��-phase formation mechanism of PFO.As a proof of concept,we further demonstrate that NPs of PFO:PS(1:8)with a higher��-phase content lead to improved photocatalyst efficiency at lower material costs,allowing for novel designs of efficient and visible-light-driven photocatalytic NPs.Xingjuan Zhao Run Li Yuechen Jia 2022ChemPhysMater2022,1,3:0
20Effects of nitrogen fertilizer on root-shoot characteristics,grain yield and nitrogen use efficiency of different maize varieties in North China Plain显示文摘Excessive nitrogen(N)fertilizer application in crop production has resulted in a series of environmental issues in North China Plain(NCP).Breeding N-efficient maize varieties is one of the effective strategies to improve the N use efficiency of maize and reduce environmental pollution.This study designed an experiment for two maize varieties(‘Xian-Yu 335’[XY335]and‘Hua-Nong 138’[HN138])with three N-level treatments(0 kg/hm^(2),180 kg/hm^(2),300 kg/hm^(2),i.e.N0,N180,N300).The aim of the study was to determine the response characteristics of maize canopy structure,root morphology,and anatomical structure,as well as N uptake and utilization of N fertilizer.Results showed that grain yield,N use efficiency,and N harvest index of XY335 were higher 5.20%-13.68%,11.86%-19.11%,and 6.07%-3.33%than those of HN138,respectively.Compared with HN138,XY335 had a higher leaf area index and photosynthetic nitrogen-use efficiency.The root length,root length density,root absorption area,root absorption area,and root active absorption area of XY335 in each period were higher than that of HN138.The proportion of RCA of XY335 was significantly higher than that of HN138,which was 14.64%higher on average.In the future breeding process,the high N and low N double-high-efficiency varieties should pay more attention to the improvement of root cortex aeration tissue.Xiangling Li Liu Pan Rui Wang Yiping Zuo Jian Wang Jinling Han Yuechen Zhang Baozhong Yin 2022International Journal of Agricultural and Biological Engineering2022,15,5:0
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