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Quasibound states in graphene quantum-dot nanostructures generated by concentric potential barrier rings

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Chinese Physics B 2012年第2期21卷 23-31页

作者： Jiang Zhao-Tan yu cheng-long Dong Quan-Li School of Physics Beijing Institute of TechnologyBeijing 100081China Beijing National Laboratory for Condensed Matter Physics Institute of PhysicsChinese Academy of SciencesBeijing 100190China

We study the quasibound states in a graphene quantum-dot structure generated by the single-, double-, and triple-barrier electrostatic potentials. It is shown that the strongest quasibound states are mainly determined by the innermost barrier. Specifically, the positions of the quasibound states are determined by the barrier height, the number of the quasibound states is determined by the quantum-dot radius and the angular momentum, and the localization degree of the quasibound states is influenced by the width of the innermost barrier, as well as the outside barriers. Furthermore, according to the study on the double- and triple-barrier quantum dots, we find that an effective way to generate more quasibound states with even larger energy level spacings is to design a quantum dot defined by many concentric barriers with larger barrier-height differences. Last, we extend our results into the quantum dot of many barriers, which gives a complete picture about the formation of the quasibound states in the kind of graphene quantum dot created by many concentric potential barrier rings.

关键词： electron structure of graphene quantum dots

Phase behavior of gas condensate in porous media using real-time computed tomography scanning

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Petroleum Science 2024年第2期21卷 1032-1043页

作者： Wen-long Jing Lei Zhang Ai-Fen Li Jun-Jie Zhong Hai Sun Yong-Fei Yang yu-long cheng Jun Yao Institute of Petroleum Engineering China University of Petroleum(East China)Qingdao266580ShandongChina National Key Laboratory of Deep Oil and Gas China University of Petroleum(East China)Qingdao266580ShandongChina

The phase behavior of gas condensate in reservoir formations differs from that in pressure-volume-temperature(PVT)cells because it is influenced by porous media in the reservoir *** was used as a sample to investigate the influence of porous media on the phase behavior of the gas *** pore structure was first analyzed using computed tomography(CT)scanning,digital core technology,and a pore network *** sandstone core sample was then saturated with gas condensate for the pressure depletion *** each pressure-depletion state was stable,realtime CT scanning was performed on the *** scanning results of the sample were reconstructed into three-dimensional grayscale images,and the gas condensate and condensate liquid were segmented based on gray value discrepancy to dynamically characterize the phase behavior of the gas condensate in porous *** network models of the condensate liquid ganglia under different pressures were built to calculate the characteristic parameters,including the average radius,coordination number,and tortuosity,and to analyze the changing mechanism caused by the phase behavior change of the gas *** types of condensate liquid(clustered,branched,membranous,and droplet ganglia)were then classified by shape factor and Euler number to investigate their morphological changes dynamically and *** results show that the dew point pressure of the gas condensate in porous media is 12.7 MPa,which is 0.7 MPa higher than 12.0 MPa in PVT *** average radius,volume,and coordination number of the condensate liquid ganglia increased when the system pressure was between the dew point pressure(12.7 MPa)and the pressure for the maximum liquid dropout,Pmax(10.0 MPa),and decreased when it was below *** volume proportion of clustered ganglia was the highest,followed by branched,membranous,and droplet *** study provides crucial experimental evidence for the phase behavior chan

关键词： Gas condensate Pressure depletion Real-time micro-computed tomography scanning Distribution of condensate liquid

FBW7 increases chemosensitivity in hepatocellular carcinoma cells through suppression of epithelial-mesenchymal transition

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Hepatobiliary & Pancreatic Diseases International 2014年第2期13卷 184-191页

作者： Jun yu Wu Zhang Feng Gao yuan-Xing Liu Zhi-yun Chen long-yu cheng Shang-Fen Xie Shu-Sen Zheng Department of Hepatobiliary and Pancreatic Surgery the First Affiliated HospitalZhejiang University School of Medicine Key Laboratory of MultiOrgan Transplantation of Ministry of Public Health

BACKGROUND: FBW7 is a tumor suppressor which regulates a network of proteins with central roles in cell division, cell growth and differentiation. This study aimed to evaluate the role of FBW7in chemosensitivity and epithelial-mesenchymal transition (EMT) in different hepatocellular carcinoma (HCC) cell lines and to investigate the relevant underlying ***: Different human HCC cell lines (Hep3B, Huh-7,and SNU-449) were cultured. The cell viability was evaluated by cell counting kit-8, and FBW7 mRNA transcription and protein expression were quantitated by real-time PCR and Western blotting. Expressions of vimentin (mesenchymal biomarker)and E-cadherin (epithelial biomarker) were evaluated by Western blotting and immunocytochemistry. Cell invasion was assayed by Transwell migration, and FBW7 plasmid or siRNA was used to evaluate the effect of FBW7 overexpression or silencing on cell ***: FBW7 expression affected tumor cell chemosensitivity to doxorubicin and tumor cell invasive capacity in different HCC cell lines. FBW7hi (high FBW7 expression) Hep3B and FBW7mi (median FBW7 expression) Huh-7 cells were more sensitive to doxorubicin and lower in invasive capacity than FBW7lo (low FBW7 expression) SNU-449 cells. Silencing of FBW7in Huh-7 and Hep3B cells induced the resistance to doxorubicin and enhanced cell invasion, whereas overexpression of FBW7in SNU-449 cells restored the sensitivity to doxorubicin andsignificantly reduced invasive capacity. Furthermore, doxorubicin induced EMT toward mesenchyme in HCC cells. Downregulation of FBW7 in Huh-7 and Hep3B cells or upregulation of FBW7 in SNU-449 cells altered the direction of ***: The level of FBW7 expression impacted the tumor resistance to doxorubicin and the invasion capability of HCC cells. FBW7 therefore may be a potential target for the chemotherapy of HCC through the regulation of EMT.

关键词： FBW7 hepatocellular carcinoma doxorubicin epithelial-mesenchymal transition drug resistance

Interactions between benzotriazole and corncob biochars pyrolyzed at different temperature

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Journal of Groundwater Science and Engineering 2016年第4期4卷 320-327页

作者： XING Chen yu cheng-long BI Er-ping DAI Jin-e School of Water Resources and Environment and Beijing Key Laboratory of Water Resources and Environment EngineeringChina University of Geosciences (Beijing) Institute of Geophysical and Geochemical Exploration Chinese Academy of Geological Sciences

The sorption of ionizable benzotriazole(BTA) to corncob biochars pyrolyzed at different temperature(i.e., 300oC, 500oC and 800oC) was investigated in this study. Biochars produced at higher temperature showed higher surface area, micropore volume and aromaticity. Consequently, the sorption of BTA changed from absorption to adsorption for biochars pyrolyzed at 300 oC and 800 oC, respectively. Solution p H affected speciation of BTA and surface charge properties of biochars. For BTA^0, H-bond, partition and micropore filling are dominant sorption mechanisms. For BTA-, it is suggested that negative charge-assisted H-bond plays an important role in sorption. Corncob biochar pyrolyzed at high temperature(e.g., 800 oC) showed the highest sorption affinity for BTA. Ca^(2+) in solution enhanced BTA^- and BTA^0 sorption through cation-bridge and surface complexation.

关键词： Benzotriazole Biochar H-bond Micropore filling Sorption Charge-assisted H-bond

Theoretical analysis on springback of L-section extrusion in rotary stretch bending process

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Transactions of Nonferrous Metals Society of China 2011年第12期21卷 2705-2710页

作者：于成龙李小强北京航空航天大学机械工程及自动化学院北京100191

The theoretical analysis of springback in rotary stretch bending process of L-section extrusion was studied. The models for characterizing the springback angle after unloading were established based on the stress and strain distributions in the cross-section of the part. With the proposed model, analysis of the effect of pre-stretch force and post-stretch force on springback angle shows that springback decreases as the pre-stretch force or post-stretch force increases. Comparative study with experiments clearly demonstrates that the prediction of springback can resort to the current model without the loss of accuracy.

关键词： springback rotary stretch bending theoretical analysis

集体化时期“男女同工同酬”的制度化:基于田野调查的再认识

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妇女研究论丛 2022年第6期 84-97页

作者：余成龙上海交通大学国际与公共事务学院上海200030

“男女同工同酬”作为集体化时期保障妇女经济权利最重要的制度安排,在实践中演变为“不同工不同酬”“同工且同酬”以及“同工不同酬”。既有研究忽略了相互矛盾的现象实际上是同一制度、相同逻辑使然。本研究基于湖北省中部开展的历... 详细信息

“男女同工同酬”作为集体化时期保障妇女经济权利最重要的制度安排,在实践中演变为“不同工不同酬”“同工且同酬”以及“同工不同酬”。既有研究忽略了相互矛盾的现象实际上是同一制度、相同逻辑使然。本研究基于湖北省中部开展的历史田野调查,尝试从“制度化”的过程视角对这段历史展开新的认识和解释。研究发现:“男女同工同酬”在借助既有文化和政治结构实现制度化的同时,也使自身陷入“平等与差异”困境,在推进男女平等的同时又固化了性别差异。与此同时,底层民众基于对公平的朴素理解,通过建立“公平—平等”内在联系、共享“公平”的内在逻辑,探索出既能激发妇女劳动热情又能平息性别争论的本土方案。因此,主导集体化时期劳动与分配的实际规则是生产效率与“性别公平”。通过“公平—平等”的路径推进性别维度的现代化虽然曲折,但在中国具有延绵持久的文化根基,同时也能对接现代社会的正义原则,这段历史为我们积蓄了实践经验并打开了进一步思考的空间。

关键词：男女同工同酬国家建构制度化平等与差异公平

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小型无人机快速三维航迹规划方法

系统工程与电子技术 2013年第12期35卷 2521-2526页

作者：刘莉于成龙王祝齐竹昌龙腾北京理工大学宇航学院北京100081

针对小型无人机航迹规划中难以满足自身性能约束和实时性要求的问题,将飞行环境中的威胁分为可穿越威胁和不可穿越威胁;基于序列规划思想,采用粒子群优化算法规划基准航迹,采用改进的稀疏A*算法进行在线航迹规划。为提高在线航迹规划效... 详细信息

针对小型无人机航迹规划中难以满足自身性能约束和实时性要求的问题,将飞行环境中的威胁分为可穿越威胁和不可穿越威胁;基于序列规划思想,采用粒子群优化算法规划基准航迹,采用改进的稀疏A*算法进行在线航迹规划。为提高在线航迹规划效率,将三维航迹规划转化为二维水平面规划和高度规划,仿真实验验证了该算法能够生成三维可行航迹,且规划时间显著减少。

关键词：航迹规划小型无人机稀疏A^*算法局部规划威胁建模

Ni-catalyzed cross-electrophile alkyl-alkyl coupling reactions

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Science China Chemistry 2025年

作者： Li-Xu You Lan Tian Chun-Ling Guo Shun-Xi Li yu-cheng Liu yu-long Li Wei Shu College of Chemistry and Environmental Engineering Key Laboratory of Green Catalysis of Higher Education Institutes of Sichuan Sichuan University of Science and Engineering Guangming Advanced Research Institute Shenzhen Grubbs Institute Department of Chemistry and Guangdong Provincial Key Laboratory of Catalysis Southern University of Science and Technology

Introducing saturated carbon-carbon bonds into organic molecules significantly increases the three-dimensional configuration,thus altering the physical and chemical properties as well as the functions of molecules. Transition-metal-catalyzed carboncarbon cross-couplings represent one of the most straightforward, efficient and modular alternatives to build saturation in a single step. However, the efficient construction of alkyl-alkyl bonds remains a formidable challenge due to the precise manipulation of multiple alkyl metallic intermediates as well as associated competitive side reactions and selectivity control. Over the past years, Ni-catalyzed cross-coupling under reductive conditions has gained more and more attention for alkyl-alkyl crosscoupling partially attributing to the low-valent state of metal centers under reducing conditions, which suppresses the competitive β-hydride elimination process, thus facilitating the formation of alkyl-alkyl bonds. In this review, the initiative and progress of Ni-catalyzed cross-electrophile alkyl-alkyl cross-coupling, including the efforts in racemic and enantioselective formation of alkyl-alkyl bonds, have been summarized and discussed. Moreover, the challenges and further opportunities in this area have also been discussed.

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南海某FPSO生产工艺系统扩容实践

船海工程 2015年第5期44卷 34-35页

作者：于成龙中海油能源发展股份有限公司采油服务分公司广东湛江524057

考虑到油田含水率的提高及打调整井、提液等增产措施的推进,为满足油田开发的需要,利用大修的机会对南海某FPSO新增一套一级分离器。实践表明,新增一级分离器后,生产工艺系统处理能力满足后续生产要求,同时将分离器中2010年进行的排沙... 详细信息

考虑到油田含水率的提高及打调整井、提液等增产措施的推进,为满足油田开发的需要,利用大修的机会对南海某FPSO新增一套一级分离器。实践表明,新增一级分离器后,生产工艺系统处理能力满足后续生产要求,同时将分离器中2010年进行的排沙口临时改造恢复到正常状态,消除安全隐患。这种扩容改造方式费用低、占用空间小、可操作性强、施工风险低。

关键词：改造扩容撇油罐一级分离器