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Phase-field crystal modeling of shape transition of strained islands in heteroepitaxy

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Science China(Physics,Mechanics & Astronomy) 2012年第11期55卷 2042-2048页

作者： chen cheng chen zheng ZHANG Jing DU XiuJuan State Key Laboratory of Solidification Processing Northwestern Polytechnical UniversityXi'an 710072China

The phase-field crystal(PFC) model is employed to study the shape transition of strained islands in heteroepitaxy on vicinal *** influences of both substrate vicinal angles β and the lattice mismatch ξ are *** increase of substrate vicinal angles is found to be capable of significantly changing the surface nanostructures of epitaxial *** surface morphology of films undergoes a series of transitions that include Stranski-Krastonov(SK) islands,the couple growth of islands and the step flow as well as the formation of step *** addition,the larger ξ indicates an increased strained island density after coarsening,and results in the incoherent growth of strained islands with the creation of misfit ***,coalescence and faceting of strained islands are also *** facets in the shape transition of strained islands are found to be stable and can be determined by β and crystal symmetry of the film.

关键词： heteroepitaxy strained islands phase field crystal

EFFECTS AND MECHANISMS OF EXTRINSIC STRENGTHENING DURING AGING FOR AL ALLOY 2090+Ce

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Transactions of Nonferrous Metals Society of China 1992年第2期2卷 76-81页

作者： chen zheng He Ming Northwestern Polytechnical University XianShanxi 710072China

The influence of aging temperature and time on fracture feature of monotonic tensile samples of alumi-num-Iithium alloy 2090+Ce was *** effects and mechanisms of extrinsic strengthening during aging for this alloy with a flat unrecrystallized structure were *** mechanisms were analysed from four *** theory of extrinsic strengthening from the delamination strengthening was *** results in this research show that the strength and ductility of aluminum-lithium alloy with a flat unrecrystallized structure are superior to those with recrystallized *** reasons have been advanced for the ductility improvement effect of flat uncrystallized structure,including wedging action between flat grain,action of short-transverse delamination on impeding the growth of main crack,action on the reduction in the detrimental influence of weak grain boundaries and action on impeding the intergranular fracture on main fracture *** strengthening effect of flat uncrystallized structure is attributed to the extrinsic strengthening derived from delamination *** underage to peakage,the fracture mode of this alloy is transgranular fracture plus short-transverse *** tendency of short-transverse delamination in creases with aging,thereby enhancing the delamination strengtheniag *** overaging condition,the fracture mode is predominately intersubgranular,which results in the loss of delamination strengthening.

关键词： Aluminum-lithium Alloy Aging Extrinsic Strengthening Delamination Strengthening Grain Structure

Correlations for the ignition delay times of hydrogen/air mixtures

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Chinese Science Bulletin 2011年第2期56卷 215-221页

作者： ZHAO ZhenLong chen zheng chen ShiYi State Key Laboratory for Turbulence and Complex Systems College of Engineering Peking University Beijing 100871 China

Correlations for the ignition delay times of hydrogen/air mixtures were developed using the method of High Dimensional Model Representation (HDMR).The hydrogen/air ignition delay times for initial conditions over a wide range of temperatures from 800 to 1600 K,pressures from 0.1 to 100 atm,and equivalence ratios from 0.2 to 10 were first calculated utilizing the full chemical *** were then developed based on these ignition delay *** forms of correlations were constructed:the first one is an overall general model covering the whole range of the initial conditions;while the second one is a piecewise correlation model valid for initial conditions within different *** performance of these correlations was studied through comparison with results from the full chemical mechanism as well as experimental *** was shown that these correlations work well over the whole range of initial conditions and that the accuracy can be significantly improved by using different piecewise correlations for different ***,piecewise correlations can be used as an effective replacement for the full mechanism when the prediction of chemical time scale is needed in certain combustion modeling.

关键词：点火延迟时间空气混合物氢化学机制开发利用模型表示温度范围一般模型

Dual-function surfactant strategy for two-dimensional organic semiconductor crystals towards high-performance organic field-effect transistors

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Science China Chemistry 2021年第6期64卷 1057-1062页

作者： zheng chen Shuming Duan Xiaotao Zhang Wenping Hu Tianjin Key Laboratory of Molecular Optoelectronic Sciences Department of ChemistrySchool of ScienceTianjin University&Collaborative Innovation Center of Chemical Science and Engineering(Tianjin)Tianjin 300072China Joint School of National University of Singapore and Tianjin University Fuzhou International Campus of Tianjin UniversityBinhai New CityFuzhou 350207China Institute of Molecular Aggregation Sciences Tianjin UniversityTianjin 300072China

Two-dimensional(2D)organic semiconductor crystals(OSCs)are ideal platforms for investigating fundament materials as well as achieving high-performance organic field-effect transistors(OFETs).The surfactants played an important role in the 2DOSCs growth in previous ***,residual surfactants may cause performance degradation of ***,a simple and effective dual-function surfactant strategy is used to control the growth of large-area few-molecular-layer *** introduction of phosphatidylcholine decreases the interfacial tension and improves the crystal growth dynamics,resulting in high-quality and large-area few-molecular-layer 2,6-bis(4-hexylphenyl)anthracene(C_6–DPA)*** additive also passivates charge traps,boosting the mobility of 2DOSC-based OFETs by almost *** method is also suitable for the growth of various high-quality 2DOSCs,opening up a new avenue for high-quality 2DOSCs towards high-performance OFETs.

关键词： two-dimensional crystals organic semiconductors organic field-effect transistors

An accurate single descriptor for ion–π interactions

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National Science Review 2020年第6期7卷 1036-1045页

作者： Zhangyun Liu zheng chen Jinyang Xi Xin Xu Collaborative Innovation Center of Chemistry for Energy Materials Key Laboratory of Molecular Catalysis and Innovative Materials MOE Key Laboratory of Computational Physical Sciences Department of Chemistry Fudan University

Non-covalent interactions between ions and π systems play an important role in molecular recognition,catalysis and biology. To guide the screen and design for artificial hosts, catalysts and drug delivery,understanding the physical nature of ion–π complexes via descriptors is indispensable. However, even with multiple descriptors that contain the leading term of electrostatic and polarized interactions, the quantitative description for the binding energies(BEs) of ion–π complexes is still lacking because of the intrinsic shortcomings of the commonly used descriptors. Here, we have shown that the impartment of orbital details into the electrostatic energy(coined as OEE) makes an excellent single descriptor for BEs of not only spherical, but also multiply-shaped, ion–π systems, highlighting the importance of an accurate description of the electrostatic interactions. Our results have further demonstrated that OEEs from a low-level method could be calibrated to BEs from a high-level method, offering a powerful practical strategy for an accurate prediction of a set of ion–π interactions.

关键词： ion–π interactions physical nature descriptors electrostatics multiply-shaped ions

Social-aware device-to-device communications underlaying cellular networks

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The Journal of China Universities of Posts and Telecommunications 2018年第1期25卷 29-36页

作者： Yu Jiang Qiu Ling chen zheng Key Laboratory of Wireless-Optical Communications University of Science and Technology of China School of Information Science and Technology University of Science and Technology of China

This article put forward a resource allocation scheme aimming at maximizing system throughtput for devide-to- device （D2D） communications underlying cellular network. Firstly, user closeness is defined and calculated through social information including friendship, interest similarity and communication strength to represent the willingness of user to share the spectrum resource with others. Then a social-aware resource allocation problem is formulated to maximize the system throughput while guaranteeing the quality of service （QoS） requirements of both D2D pairs and cellular users （CUs）. Then the complicate problem is decomposed into three subproblems. Firstly the admissible D2D pairs are determined and then the power of both CUs and D2D pairs is efficiently allocated. Finally CUs and D2D pairs are matched to reuse the spectrum resource in consideration of both user closeness and physical conditions. Simulation results certify the effectiveness of the proposed scheme which significantly enhances the system throughput compared with the existing algorithms.

关键词： D2D communication user closeness social-aware resource allocation

Multifunctional ultrasmall Pd nanosheets for enhanced near-infrared photothermal therapy and chemotherapy of cancer

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Nano Research 2015年第1期8卷 165-174页

作者： Shaoheng Tang Mei chen Nanfeng zheng State Key Laboratory for Physical Chemistry of Solid Surfaces Collaborative Innovation Center of Chemistry for Energy Materials andDepartment of Chemis try College of Chemistry and Chemical Engineering Xiamen University Xiamen Fujian 361005 China

Near-infrared （NIR） photothermal therapy has developed very quickly in recent years. However, its clinical applications are hindered by many practical problems, such as low accumulation in tumors, high laser power density and high biotoxicity in vivo. Herein, a versatile system combining chemotherapy with photothermal therapy for cancer therapy using ultrasmall Pd nanosheets （SPNS） has been developed. The SPNS can serve as pH-responsive drug carriers to efficiently deliver DOX into cancer cells and tumors. On the other hand, the coordinative loading of DOX on SPNS enhances its accumulation in tumor tissue. So we can efficiently ablate tumor using low-intensity laser radiation. Importantly, with ultrasmall size （-4.4 nm）, SPNS surface-functionalized with reduced glutathione （GSH） can be cleared from the body through the renal system into the urine. This cancer therapeutic nanosystem, which exhibits a significant synergistic effect and low systemic toxicity, has great potential for clinical applications.

关键词： photothermal therapy chemotherapy Pd nanosheets drug delivery synergistic effect

Neuroprotective role of fibronectin in neuron-glial extrasynaptic transmission

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Neural Regeneration Research 2013年第4期8卷 376-382页

作者： Jintang Wang Ling Yin zheng chen Institute for Geriatric Clinic and Rehabilitation Beijing Geriatric Hospital Institute of Medical Informatics General Hospital of PLA

Most hypotheses concerning the mechanisms underlying Parkinson＇s disease are based on altered synaptic transmission of the nigrostriatal system. However, extrasynaptic transmission was recently found to affect dopamine neurotransmitter delivery by anisotropic diffusion in the extracellular matrix which is modulated by various extracellular matrix components such as flbronectin. The present study reviewed the neuroprotective effect of fibronectin in extrasynaptic transmission. Fibronectin can regulate neuroactive substance diffusion and receptor activation, and exert anti- neuroinflammatory, adhesive and neuroprotective roles. Fibronectin can bind to integrin and growth factor receptors to transactivate intracellular signaling events such as the phosphatidylinositol 3-kinase/protein kinase B pathway to regulate or amplify growth factor-like neuroprotective actions. Fibronectin is assembled into a fibrillar network around cells to facilitate cell migration, molecule and ion diffusion, and even drug delivery and treatment. In addition, the present study analyzed the neuroprotective mechanism of fibronectin in the pathogenesis of Parkinson＇s disease, involving integrin and growth factor receptor interactions, and discussed the possible therapeutic and diagnostic significance of fibronectin in Parkinson＇s disease.

关键词： neural regeneration neurodegenerative diseases Parkinson's disease fibronectin integrin extrasynaptic transmission neuroglia neuroprotection grants-supported paper photographs-containing paper neuroregeneration

Identification of MicroRNAs in Wild Soybean (Glycine soja)

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Journal of Integrative Plant Biology 2009年第12期51卷 1071-1079页

作者： Rui chen zheng Hu Hui Zhang The National Key Facilities for Crop Genetic Resources and Improvement Institute of Crop Sciences Chinese Academy of Agricultural Sciences Beijing 100081 China

MicroRNAs （miRNAs） play important roles in post-transcriptional gene silencing by directing target mRNA cleavage or translational inhibition. Currently, hundreds of miRNAs have been identified in plants, but no report has been published of wild soybean （Glycine soja Sieb）. We constructed a small-RNA library consisting of 2 880 sequences with high quality, in which 1 347 were 19-24 nt in length. By utilizing the miRNA, Rfam and domesticated soybean expressed sequence tag database, we have analyzed and predicted the secondary structure of these small RNAs. As a result, t5 conserved miRNA candidates belonging to eight different families and nine novel miRNA candidates comprising eight families were identified in wild soybean seedlings. All these miRNA candidates were validated by northern blot and the novel candidates expressed in a tissue-specific manner. Furthermore, putative target genes were predicted for novel miRNA candidates and two of them were verified by 5＇-rapid amplification of cDNA ends experiments. These results provided useful information for miRNA research in wild soybean and plants.

关键词： microRNAs plants wild soybean.