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Impact of alkyl chain branching positions on molecular packing and electron transport of dimeric perylenediimide derivatives

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Journal of Energy Chemistry 2019年第8期28卷 138-143,I0006页

作者： yuan guo Guangchao Han yuanping Yi Beijing National Laboratory for Molecular Sciences CAS Key Laboratory of Organic Solids CAS Research/Education Center for Excellence in Molecular Sciences Institute of Chemistry Chinese Academy of SciencesBeijing 100190 China University of Chinese Academy Sciences Beijing 100049 China

Side chains play a critical role in tuning intermolecular interaction and charge transport in organic semiconductors. Here, we have systematically investigated the impact of branching positions of the alkyl side chains on the molecular packing and electron transport properties of a series of bay-linked dimeric perylenediimide(PDI) derivatives by atomistic molecular dynamics simulations in combination with charge transfer rate theory and kinetic Monte Carlo simulations. The results show that despite of different branching positions of the alkyl chains,π–π stacking is effectively inhibited for all the dimeric PDI derivatives. As the branching position moves away from the PDI backbone, the appearance of the alkyl atoms around the PDI backbone will first decrease and then increase. Correspondingly, the short contacts between the PDI moieties are first enhanced and then reduced. In particular, when the branching position is at the third carbon atom, the intermolecular connectivity becomes the most effective and the electron mobility is significantly increased by 2 times.

关键词： Molecular packing Electron mobility Branching position Perylenediimide

Observer-based multivariable fixed-time formation control of mobile robots

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Journal of Systems Engineering and Electronics 2020年第2期31卷 403-414页

作者： LI Yandong ZHU Ling and guo yuan College of Computer and Control Engineering Qiqihar UniversityQiqihar 161006China School of Mechanical and Electronic Engineering Qiqihar UniversityQiqihar 161006China

This paper proposes a multivariable fixed-time leaderfollower formation control method for a group of nonholonomic mobile robots, which has the ability to estimate multiple uncertainties. Firstly, based on the state space model of the leader-follower formation, a multivariable fixed-time formation kinematics controller is designed. Secondly, to overcome uncertainties existing in the nonholonomic mobile robot system, such as load change,friction, external disturbance, a multivariable fixed-time torque controller based on the fixed-time disturbance observer at the dynamic level is designed. The designed torque controller is cascaded with the formation controller and finally realizes accurate estimation of the uncertain part of the system, the follower tracking of reference velocity and the desired formation of the leader and the follower in a fixed-time. The fixed-time upper bound is completely determined by the controller parameters, which is independent of the initial state of the system. The multivariable fixed-time control theory and the Lyapunov method are adopted to ensure the system ***, the effectiveness of the proposed algorithm is verified by the experimental simulation.

关键词： multivariable fixed-time control formation control uncertainty fixed time observer nonholonomic mobile robot

Discovery potential of the Glashow resonance in an air shower neutrino telescope

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Chinese Physics C 2024年第8期48卷 266-275页

作者： guo-yuan Huang School of Mathematics and Physics China University of GeosciencesWuhan 430074China Max-Planck-Institut für Kernphysik Saupfercheckweg 169117 HeidelbergGermany

The in-ice or in-water Cherenkov neutrino telescope,such as IceCube,has already proved its power in measuring the Glashow resonance by searching for the bump around E_(ν)=6.3PeV arising from the W-boson *** are many proposals for the next few decades for observations of cosmic tau neutrinos with extensive air showers,also known as tau neutrino *** air shower telescope is,in principle,sensitive to the Glashow resonance via the channel W→τν_(τ)followed by the tau decay in the air(e.g.,TAMBO,which has a geometric area of approximately 500km^(2)).Using a thorough numerical analysis,we find that the discovery significance can be up to 90%with a TAMBO-like setup if PeV neutrinos primarily originate from neutron decays,considering the flux parameters measured by IceCube as the *** presence of new physics affecting the neutrino flavor composition can also increase the ***,if ultrahigh-energy neutrinos are dominantly produced from meson decays,it will be statistically difficult for an advanced proposal such as TAMBO to discriminate the Glashow resonance induced byν¯e from the intrinsicντ/ν¯_(τ)*** have identified several limitations for such advanced telescopes,in comparison with the in-ice or in-water telescope,when measuring resonances:(i)a suppressed branching ratio of 11%for the decay W→τν_(τ);(ii)the smearing effect and reduced acceptance because the daughter neutrino takes away(y)∼75%of the energy from the W decay;and(iii)a large attenuation effect for Earth-skimming neutrinos with the resonance.

关键词： Ultrahigh-energy neutrinos Neutrino telescopes Glashow resonance

Gas-Fluid and Fluid-Solid Phase Instability for Restricted Primitive Model

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Communications in Theoretical Physics 2009年第8期52卷 356-360页

作者： guo yuan-yuan CHEN Xiao-Song Key Laboratory of Frontiers in Theoretical Physics Institute of Theoretical Physics Chinese Academy of SciencesP.O. Box 2735 Beijing 100190 China

By considering the fluctuation of grand potential f~ around equilibrium with respect to small one-particle density fluctuations δpα（r→）, the phase instability of restricted primitive model （RPM） of ionic systems is investigated. We use the integral equation theory to calculate the direct correlation functions in the reference hypernetted chain approximation and obtain the spinodai line of RPM. Our anaiysis explicitly indicates that the gas-fluid phase instability is induced by k = 0 fluctuation mode, while the fluid-solid phase instability is related to k ≠ 0 fluctuation modes. The spinodai line is qualitatively consistent with the result of computer simulations by others.

关键词： phase instability restricted primitive model the reference hypernetted chain approximation

DNA methylation and microRNAs in cancer

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World Journal of Gastroenterology 2012年第9期18卷 882-888页

作者： Xiang-Quan Li yuan-yuan guo Wei De Department of Bio-chemistry and Molecular Biology Nanjing Medical UniversityNanjing 210029Jiangsu ProvinceChina

DNA methylation is a type of epigenetic modification in the human genome,which means that gene expression is regulated without altering the DNA *** and the relationship between methylation and cancer have been the focus of molecular biology *** represses gene expression and can influence embryogenesis and *** different tissues and at different stages of life,the level of methylation of DNA varies,implying a fundamental but distinct role for *** genes are repressed by abnormal methylation,the resulting effects can include instability of that gene and inactivation of a tumor suppressor *** have some aspects in common with this regulation of gene *** we reviewed the influence of gene methylation on cancer and analyzed the methods used to profile *** also assessed the correlation between methylation and other epigenetic modifications and *** 55 845 research papers have been published about methylation,and one-fifth of these are about the appearance of methylation in *** conclude that methylation does play a role in some cancer types.

关键词： Methylation gene expression Transcriptionalcontrol Cancer MicroRNA Gastric cancer

Microstructure and mechanical properties of hot-rolled low-carbon steel containing Ti–Ca oxide particles: a comparison between base metal and HAZ

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Journal of Iron and Steel Research International 2020年第4期27卷 440-450页

作者： Chao Wang Xin Wang Jian Kang guo yuan guo-dong Wang The State Key Laboratory of Rolling and Automation Northeastern UniversityShenyang 110819LiaoningChina

The effect of inclusion-induced nucleation on hot-rolled steel base metal was evaluated in comparison with welding heataffected zone(HAZ).Microstructure and mechanical properties of hot-rolled low-carbon steel containing Ti–Ca oxide particles were *** results showed that inclusions in Ti–Ca deoxidized steel distributed dispersely and were effective for intragranular acicular ferrite *** hot rolling and controlled cooling conditions,microstructure in steel base metal was significantly refined and mainly consisted of acicular ferrite and intragranular bainite,which exhibited higher strength and excellent *** microstructural evolution behavior followed the process that acicular ferrite plates divided the austenite grain,intragranular bainite packets formed between interlocking acicular ferrite plates,and the remaining austenite decomposed into fine polygonal ferrite *** resultant complex microstructure improved the impact toughness *** comparison,in HAZ microstructure,laminar grain boundary ferrite having similar crystallography orientation showed adverse effect on toughness.

关键词： Low-carbon steel Ti–Ca oxide Hot rolling Mechanical property Acicular ferrite Heat-affected zone

Effects of bismuth on growth of intermetallic compounds in Sn-Ag-Cu Pb-free solder joints

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中国有色金属学会会刊：英文版 2006年第B2期16卷 739-743页

作者： LI guo-yuan SHI Xun-qing School of Materials Science and Engineering Nanyang Technological University Singapore 639798 Intel Technology Development Ltd Shanghai 200131 China

The effects of Bi addition on the growth of intermetallic compound (IMC) formation in Sn-3.8Ag-0.7Cu solder joints were investigated. The test samples were prepared by conventional surface mounting technology. To investigate the element diffusion and the growth kinetics of intermetallics formation in solder joint, isothermal aging test was performed at temperatures of 100, 150, and 190℃, respectively. The optical microscope (OM) and scanning electron microscope (SEM) were used to observe microstructure evolution of solder joint and to estimate the thickness and the grain size of the intermetallic layers. The IMC phases were identified by energy dispersive X-ray (EDX) and X-ray diffractometer (XRD). The results clearly show that adding about 1.0% Bi in Sn-Ag-Cu solder alloy system can refine the grain size of the IMC and inhibit the excessive IMC growth in solder joints, and therefore improve the reliability of the Pb-free solder joints. Through observation of the microstructural evolution of the solder joints, the mechanism of inhibition of IMC growth due to Bi addition was proposed.

关键词： Sn-Ag-Cu合金无铅焊料铋焊接接头金属间化合物

Sustainability of the rice-crayfish farming model in waterlogged land:A case study in Qianjiang County, Hubei Province, China

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Journal of Integrative Agriculture 2022年第4期21卷 1203-1214页

作者： yuan Peng-li WANG Jin-ping guo Can guo Zi-yuan guo Yao CAO Cou-gui Laboratory of Crop Ecophysiology and Farming System in the Middle Reaches of Yangtze River College of Plant Science and TechnologyHuazhong Agricultural UniversityWuhan 430070P.R.China Hubei Collaborative Innovation Center for Grain Industry Yangtze UniversityJingzhou 434023P.R.China

The rice-crayfish farming model has been rapidly developed and become an economically viable method to supply food in China in recent ***,its environmental and economic sustainability has not been thoroughly *** study uses a survey in 2016 and a field experiment in 2017 in Qianjiang,Hubei Province,China to assess the relative economics of concurrent rice-wheat(RW),rice-crayfish(RC),and crayfish monoculture(CM)models in waterlogged land *** survey indicated that the RC model had a higher benefit-cost ratio(3.5:1)than the RW(2.0:1)and CM(3.1:1)models and the RC model protected farmers’enthusiasm for grain production facing unfavourable weather *** field experiment aimed to explore nitrogen management strategies in RC *** the experiment,four levels of nitrogen concentration gradient-0 kg N ha^(-1)(0 N),75 kg N ha^(-1)(75 N),150 kg N ha^(-1)(150 N)and 225 kg N ha^(-1)(225 N),were set in a 2-year-old rice-crayfish(RC2)field,an 8-year-old rice-crayfish(RC8)field,and a RWfield as a *** experiment results suggested that the peak rice yield in RW,RC2,and RC8 occurred when 225 N,150 N and 75 N were used,*** RC2 and RC8,however,residual feed-nitrogen that was not used by crayfish was utilized by rice ***,an optimal amount of nitrogen in RCfields was proposed to improve the nitrogen use efficiency and reduce environmental pollution by nitrogen *** use less nitrogen but have higher net income in RC than in RW and *** is necessary to sustainably develop integrated farming technologies(i.e.,properfield configurations for ricefields)to effectively sustain rice *** results also showed that the RC farming model was a viable diversification option for rice farmers in waterlogged land.

关键词： rice–crayfish benefit-cost ratio lodging nitrogen application

Influence of particle shape on the erodibility of non-cohesive soil： Insights from coupled CFD-DEM simulations

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Particuology 2018年第4期16卷 12-24页

作者： yuan guo Yang Yang Xiong (Bill) Yu Department of Civil Engineering Case Western Reserve University 2104 Adelbert Road Bingharn 269 Cleveland OH 44106-7201 USA Department of Electrical Engineering and Computer Science Case Western Reserve University 2104 Adelbert Road Bingharn 203D Cleveland OH 44106-7201 USA Departrnent of Civil Engineering Case Western Reserve University 2104 Adelbert Road Bingharn 206 Cleveland OH 44106- 7201 USA

Soil erosion is a critical process that is being studied in soil science, hydraulic engineering, and geotech- nical engineering. Among many societal and environmental impacts, soil erosion is a major cause for the failures of bridges. The erodibility of soil is determined by its physical and geochemical properties and is also affected by surrounding biological activities. In most of the current models for soil erosion, erodibility of non-cohesive soil is characterized by its median grain size （Dso）, density, and porosity. The contribution to erodibility of the irregular shape of soil grains, which plays an important role in the mechanical and hydraulic properties of coarse-grained soils, is generally ignored. In this paper, a coupled computational fluid dynamics and discrete element method model is developed to analyze the influence of the shape of sand grain on soil erodibility. A numerical model for the drag force on spherical and non-spherical particles is verified by using the results from physical free settling experiments. Erosion of sand grains of different shapes is simulated in a virtual erosion function apparatus, a laboratory device used to mea- sure soil erodibility. The simulation results indicate that the grain shape has major effects on erodibility. Spherical particles do not show a critical velocity because of their low rolling resistance, but a critical velocity does exist for angular particles owing to grain interlocking. The erosion rate is proportional to the flow velocity for both spherical and non-spherical particles. The simulation result for angular particle erosion is fairly consistent with the experimental observations, implying that grain shape is an important factor affecting the erodibility of non-cohesive soils.

关键词： CFD-DEM Soil erosion Grain shape Erodibility of coarse-grained soil Erosion function apparatus mode