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高校扩招、学历回报与高考复读——基于复读博弈模型的理论与实证

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财经科学 2024年第4期 92-107页

作者：王湛郑智文王帝西南财经大学中国西部经济研究院西南财经大学中国行为经济与行为金融研究中心

本文通过建立复读博弈模型进行理论分析,发现明确的高校学历信号差异会导致考生付出一定成本,选择复读提高考试能力以获得更高的学历。一旦出现复读,在动态演化后,复读人数和高考难度最终会达到一个比较高的稳定水平。而高校扩招会通过... 详细信息

本文通过建立复读博弈模型进行理论分析,发现明确的高校学历信号差异会导致考生付出一定成本,选择复读提高考试能力以获得更高的学历。一旦出现复读,在动态演化后,复读人数和高考难度最终会达到一个比较高的稳定水平。而高校扩招会通过扩大高校间信号收益的差距进一步提高这个稳定水平,其中学历信号相对低的高校扩招导致复读增加的效应更加明显。实证结果表明,高校扩招使得大学专科和本科学历的信号收益显著降低,且前者降低更多。复读率受4年前的高校扩招的影响最大,4年前高校每扩招1%,复读率就会上升0.09%左右。这些实证结果与理论结论一致。

关键词：高考复读高校扩招信号博弈

半边街滑坡形成机制与基于有限元模拟的多场演化特征

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科技和产业 2024年第14期24卷 281-288页

作者：郑志文孙玄湖北省神龙地质工程勘察院有限公司武汉430050

半边街滑坡属于典型的降雨型堆积层滑坡,在降雨作用下产生了较大程度的变形破坏,仍在继续发展。对半边衔滑坡地质条件与破坏特征进行了调查与分析,阐述了滑坡的变形机制。建立基于有限元的滑坡数值模型,采用渗流-应力耦合分析方法,研究... 详细信息

半边街滑坡属于典型的降雨型堆积层滑坡,在降雨作用下产生了较大程度的变形破坏,仍在继续发展。对半边衔滑坡地质条件与破坏特征进行了调查与分析,阐述了滑坡的变形机制。建立基于有限元的滑坡数值模型,采用渗流-应力耦合分析方法,研究了不同降雨工况下滑坡的稳定性及渗流场、位移场演化特征。结果表明滑坡位移主要受控于渗流场变化,在连续数天的暴雨或大暴雨工况下,极有可能产生整体滑动。研究成果为今后此类滑坡的预警、治理工程提供重要的理论依据。

关键词：滑坡降雨入渗数值模拟稳定性渗流场

Structural features of 18R-type long-period stacking ordered phase in Mg85Zn6Y9 alloy and the Ni doping effect on its hydrogen storage properties

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Journal of Materials Science & Technology 2023年第14期145卷 148-155页

作者： zhiwen zheng Cong Peng Qingan Zhang School of Materials Science and Engineering Anhui University of TechnologyMaanshanAnhui 243002China

Magnesium-based alloys with 18R-type long-period stacking ordered(LPSO)structures have attracted wide attention for structural and functional *** understand hydrogen storage properties of 18R phase,the Mg_(85)Zn_(6)Y_(9)alloy with 94 wt.%of 18R-type LPSO phase is prepared in this *** 18R phase has a layered structure where Y-Zn-Mg and Mg layers alternately stack along the *** the Y-Zn-Mg layers,Y,Zn and partial Mg sites are co-occupied by Y and Mg,Zn and Mg,and Mg and Zn/Y atoms,*** the 18R phase is easily decomposed intoα-MgH_(2),γ-MgH_(2),YH_(2),YH_(3),C14-type Laves phase MgZn_(2)and minor CsCl-type Y(Mg,Zn)during ball milling under hydrogen ***-ter further hydrogen absorption-desorption cycling,Y(Mg,Zn)disappears gradually and C14 phase trans-forms into C15-type Laves *** contrast,the Mg_(85)Zn_(6)Y_(9)alloy has better hydrogen storage kinetics and cycle durability than pure Mg because of the catalytic effect of YH_(2)/YH_(3)on hydrogen absorption-desorption and inhibition role of Laves phase in Mg crystallite ***,the introduction of Ni into Mg_(85)Zn_(6)Y_(9)sample leads to a further decrease in activation energy of hydrogen desorption from 106.39 to 96.78 kJ mol−1 due to the formation of Mg_(2)*** work not only provides new insights into structural features and hydrogen storage characteristics of 18R phase but offers an effective method for improving hydrogen storage properties.

关键词： Mg-based alloy Magnesium hydride Crystal structure Hydrogen storage

PCL-based and Hirudin-containing Composite Nanofibers for Prolonged Anticoagulation Effect

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Chemical Research in Chinese Universities 2023年第6期39卷 1023-1030页

作者： zheng zhiwen DAI Xin LI Xueyang DU Chang Department of Biomaterials School of Materials Science and EngineeringSouth China University of TechnologyGuangzhou 510641P.R.China National Engineering Research Center for Tissue Restoration and Reconstruction South China University of TechnologyGuangzhou 510006P.R.China NMPA Key Laboratory for Research and Evaluation of Innovative Biomaterials for Medical Devices South China University of TechnologyGuangzhou 510006P.R.China Key Laboratory of Biomedical Materials and Engineering Ministry of EducationSouth China University of TechnologyGuangzhou 510006P.R.China

More and more concerns about health bring the increasing demand for blood contact tissue engineering *** this paper,nanoparticles of poly(lactic-co-glycolic acid)/polyethyleneimine mixed with recombinant hirudin(rHNPs)were prepared by a double emulsion solvent volatilization method,which were then loaded onto the polycaprolactone(PCL)with polydopamine(PDA)coating to form the composite nanofibers of PCL/PDA/*** hydrophilicity and mechanical properties of the composite nanofibers were improved significantly compared with pure *** morphology kept almost unchanged after 30 d of degradation in phosphate buffer saline(PBS).The anticoagulant molecule of hirudin could be gradually released from the composite scaffolds through the degradation of rHNPs in *** the concentration of rHNPs suspension was 5.0 mg/mL,the composite nanofibers could better promote the growth and proliferation of human umbilical vein endothelial cells(HUVECs).The anticoagulant ability of the composite nanofibers was also significantly improved in comparison with that of pure *** design of controlled release anticoagulant materials would alleviate the sudden release of simple fixed hirudin,which could also provide a new idea for the development of novel blood contact materials.

关键词： Recombinant hirudin Anticoagulation Drug release Composite nanofiber

Insight into macroscale superlubricity of polyol aqueous solution induced by protic ionic liquid

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Friction 2022年第12期10卷 2000-2017页

作者： zhiwen zheng Xiaolong LIU Hongxiang YU Haijie CHEN Dapeng FENG Dan QIAO State Key Laboratory of Solid Lubrication Lanzhou Institute of Chemical PhysicsChinese Academy of SciencesLanzhou 730000China Center of Materials Science and Optoelectronics Engineering University of Chinese Academy of SciencesBeijing 100049China

Currently,macroscale liquid superlubricity remains limited to low applied loads and typical ceramic friction *** this study,a robust macroscale superlubricity with a coefficient of friction(COF)of approximately 0.006 is realized at the bearing steel interface induced by protic ionic liquids(ILs)in propylene glycol aqueous solution,and the lubrication system exhibits excellent anti-corrosion *** show that superlubricity can be achieved by employing ILs with longer alkyl chains over a wide load(700 r/min)*** systematically investigating factors affecting superlubricity,including the IL structure,ionization degree,test conditions,polyol,water-to-alcohol ratio,and lubrication state,the superlubricity mechanism is ***,a thicker and denser stern layer can be formed using ILs with longer alkyl chains,which participates in the tribochemical reaction with the metal substrate to form a tribofilm during *** hydrogen bond network layer formed by the hydrogen ion and polycol aqueous solution can withstand high applied *** can be used to reduce the shear stress of polyols,and enable superlubricity to be achieved under high-speed ***,an inevitable running-in period serves as a dispersing contact stress and dynamically forms a lubricating film,where the lubrication state locates mixed lubrication and then transforms into boundary lubrication as the roughness of the contact surface *** study is expected to significantly promote the development and application of superlubricity in the engineering field.

关键词： macroscale superlubricity ionic liquids(ILs) steel interface corrosion tribochemical reaction

PROBING MOLECULAR INTERACTION BETWEEN TRANSFERRIN AND ANTI-TRANSFERRIN BY ATOMIC FORCE MICROSCOPE

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Chinese Science Bulletin 2006年第4期51卷 405-408页

作者： zheng zhiwen YANG Peihui ZENG Gucheng CAI Jiye Key Laboratory of Specially Functional Materials and AdvancedManufacturing Technology Ministry of Education South China University of Technology Guangzhou 510640 China Department of Chemistry Jinan University Guangzhou 510632 China

The interaction between transferrin (Tf) and its antibody was investigated by atomic force microscope. Tf-antibody was immobilized on the Au-coated glass slide, and the specific combination between antibody and antigen was also character-ized by AFM. The results showed that holo-transferrin was jogged with anti-transferrin, and binded anti-tran- sferrin more tightly than apo-transferrin. The force- distance curves revealed that the affinity of anti-trans- ferrin and holo-transferrin was much stronger than that of apo-transferrin.

关键词：转铁球蛋白抗转铁球蛋白分子间相互作用原子力显微镜生物大分子

Effect of functional groups on tribological properties of lubricants and mechanism investigation

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Friction 2023年第6期11卷 911-926页

作者： Hongxiang YU Haijie CHEN zhiwen zheng Dan QIAO Dapeng FENG Zhenbin GONG Guojun DONG State Key Laboratory of Solid Lubrication Lanzhou Institute of Chemical PhysicsChinese Academy of SciencesLanzhou730000China Center of Materials Science and Optoelectronics Engineering University of Chinese Academy of SciencesBeijing100049China

Nine organic compounds were utilized as model lubricants to investigate the impact of functional groups on tribological *** Acid with carboxyl showed the best lubrication properties,and fluid film and tribofilm were coexistent in its friction test,bringing a low friction coefficient and wear *** addition,the lubricant with low friction coefficient corresponded to high adsorption energy in density functional theory(DFT)*** the lubricant forming adsorption film with large surface energy displayed small wear rate in friction ***,adsorption energies positively correlated surface *** on the experimental results,the action mechanism of functional groups on tribological properties of lubricants was *** functional groups make lubricant molecules show different adsorption energies and surface *** molecules with high adsorption energy are more likely to adsorb on substrates and form a vertical monolayer,which can maintain a regular molecular brush structure during friction and bring a low friction *** lubricant molecules with high surface energy may be more prone having tribochemical reactions during friction and forming protective tribofilm,which leads to a low wear rate.

关键词： functional group tribological property adsorption energy surface energy action mechanism

Macroscale superlubricity achieved via hydroxylated hexagonal boron nitride nanosheets with ionic liquid at steel/steel interface

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Friction 2022年第9期10卷 1365-1381页

作者： zhiwen zheng Xiaolong LIU Guowei HUANG Haijie CHEN Hongxiang YU Dapeng FENG Dan QIAO State Key Laboratory of Solid Lubrication Lanzhou Institute of Chemical PhysicsChinese Academy of SciencesLanzhou 730000China University of Chinese Academy of Sciences Beijing 100049China State Key Laboratory of Advanced Processing and Recycling of Nonferrous Metals Lanzhou University of TechnologyLanzhou 730050China

Macroscale superlubricity is a prospective strategy in modern tribology to dramatically reduce friction and wear of mechanical equipment;however,it is mainly studied for point-to-surface contact or special friction pairs in *** this study,a robust macroscale superlubricity for point-to-point contact on a steel interface was achieved for the first time by using hydroxylated modified boron nitride nanosheets with proton-type ionic liquids(ILs)as additives in ethylene glycol aqueous(EG_(aq)).The detailed superlubricity process and mechanism were revealed by theoretical calculations and segmented *** results indicate that hydration originating from hydrated ions can significantly reduce the shear stress of EG_(aq),which plays an essential role in achieving ***,the IL induces a tribochemical reaction to form a friction-protective *** boron nitride nanosheets(HO-BNNs)function as a polishing and self-repairing agent to disperse the contact stress between friction *** involves the change in lubrication state from boundary lubrication to mixed *** finding can remarkably extend the application of superlubricity for point-to-point contact on steel surfaces for engineering applications.

关键词： macroscale superlubricity ionic liquid(IL) hydroxylated boron nitride steel/steel interface mixed lubrication

核磁共振氢谱多维度探究1,3-二羰基化合物的酮-烯醇互变异构规律

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大学化学 2024年第7期39卷 361-367页

作者：梁倬铭陈铭郑智文陈凯中南大学化学化工学院长沙410083

针对大学有机化学实验“核磁共振氢谱测定乙酰乙酸乙酯互变异构体”存在内容单一、教学深度与广度不足等问题进行了改进创新。实验内容由认识酮-烯醇互变异构的存在,拓展到探究时间、取代基以及溶剂三个维度对β-二羰基化合物的酮-烯醇... 详细信息

针对大学有机化学实验“核磁共振氢谱测定乙酰乙酸乙酯互变异构体”存在内容单一、教学深度与广度不足等问题进行了改进创新。实验内容由认识酮-烯醇互变异构的存在,拓展到探究时间、取代基以及溶剂三个维度对β-二羰基化合物的酮-烯醇互变异构平衡的影响。此外,在研究甲醇溶剂对平衡的影响时,可以观测到氢氘交换现象,有助于进一步理解异构过程的机理。本实验可针对化学相关专业高年级本科生开展,有助于加深学生对酮性质的理解,掌握核磁共振波谱在有机化学中的应用,从而巩固有机化学和仪器分析的理论知识,以及培养学生分析问题、解决问题的能力。

关键词：乙酰乙酸乙酯互变异构核磁共振氢谱

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