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The Physical Chemistry for the Self-assembly of Peptide Hydrogels

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Chinese Journal of Polymer Science 2018年第3期36卷 366-378页

作者： Ying Li Yi cao Collaborative Innovation Center of Atmospheric Environment and Equipment Technology School of Environmental Science and EngineeringJiangsu Engineering Technology Research Centre of Environmental Cleaning MaterialsJiangsu Key Laboratory of Atmospheric Environment Monitoring and Pollution ControlJiangsu Joint Laboratory of Atmaspheric Pollution ControlNanjing University of Information Science&TechnologyNanjing 210044China Collaborative Innovation Center of Advanced Microstrucures National Laboratony of Solid State MicrostrucureDepartment of PhysicsNanjing UniversityNanjing 210093China

Peptide hydrogels have been widely used for diverse biomedical applications. However, our current understanding of the physical principles underlying the self-assembly process is still limited. In this review, we summarize our current understanding on the physical chemistry principles from the basic interactions that drive the self-assembly process to the energy landscapes that dictate the thermodynamics and kinetics of the process. We discuss the effect of different factors that affect the kinetics of the self-assembly of peptide fibrils and how this is related to the macroscopic gelation process. We provide our understanding on the molecular origin of the complex and rugged energy landscape for the self-assembly of peptide hydrogels. The hierarchical self-assembled structures and the diverse self-assembling mechanism make it difficult and challenging to rationally design the physical and chemical properties of peptide hydrogels at the molecular revel. We also give our personal perspective to the potential future directions in this field.

关键词： Hydrogel Peptide Self-assembly Kinetics Thermodynamics

Parametric Vibration Stability Analysis of a Pyramid Lattice Sandwich Plate Subjected to Pulsatile External Airflow

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Acta Mechanica Solida Sinica 2023年第1期36卷 95-104页

作者： Zhiwei cao Guo Yao School of Mechanical Engineering and Automation Northeastern UniversityShenyang 110819China

Lattice sandwich structures are broadly used in aerospace,navigation,and high-speed rail *** engineering practice,the airflow outside the vehicle or aircraft always exhibits the pulsatile property,which makes the elastic structural components and the external airflow a parametric excitation *** this paper,the parametric vibration stability analysis and dynamic characteristics of a lattice sandwich plate interacting with the pulsatile external airflow are *** equation of motion is derived using Hamilton’s principle and discretized using the assumed mode *** linear potential flow theory is applied to derive the perturbation aerodynamic *** stability of the system is analyzed using the Floquet theory and validated by numerical *** effects of design parameters of the lattice sandwich plate on the stability of the system are *** the simulations and discussions,some practical principles for the optimal design of lattice sandwich structures in the aerodynamic environment are proposed.

关键词： Lattice sandwich structures Pulsatile airflow Parametric excitation Floquet theory

Video-Driven 2D Character Animation

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Chinese Journal of Electronics 2021年第6期30卷 1038-1048页

作者： YIN Qinran cao Weiqun School of Information Science and Technology Beijing Forestry University Engineering Research Center for Forestry-oriented Intelligent Information Processing of National Forestry and Grassland Administration

Video-driven animation has always been a hot and challenging topic in the field of computer animation. We propose a method of mapping a sequence of human skeletal keypoints in a video onto a two-dimensional character to generate 2 D character animation. For a given two-dimensional character picture, we extract the motion of real human in video data, driving the character deformation. We analyze common two-dimensional human body movements, classify the basic posture of the human body, realize the recognition of skeleton posture based on back propagation network, capture human body motion by automatically tracking the position of the human skeleton keypoints coordinates in the video and redirect the motion data to a 2 D character. Compared with the traditional method, our work is less affected by video data illumination and background complexity. We calibrate human body motion in videos to a 2 D character according to the skeleton topology to avoid motion distortion caused by the difference in skeleton size and ratio. The experimental results show that the proposed algorithm can generate the motion of two-dimensional characters based on the motion of human characters in video data. The animation is natural and smooth, and the algorithm has strong robustness.

关键词： two-dimensional character picture motion distortion skeleton size video data illumination human characters video signal processing computer animation character deformation basic posture two-dimensional human body movements background complexity hot topic motion data video-driven animation computational geometry human skeleton keypoints skeleton topology skeleton posture human skeletal keypoints video-driven 2D character animation capture human body motion

Effect of Rotor-stator Axial Gap on the Tip Seal Leakage Flow of a Steam Turbine

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Journal of Thermal Science 2021年第3期30卷 973-982页

作者： LI Pan cao Lihua School of Energy and Power Engineering Northeast Electric Power UniversityJilin 132012China

The tip leakage flow in different axial gaps is numerically investigated based on the Reynolds-Averaged Navier-Stokes equations and k-ω SST turbulent model using commercial CFD software ANSYS *** characteristics of vortexes in the flow field of tip seal and the distribution law of rotor tip leakage loss are analyzed under the change of axial *** results show that the flow field in the blade tip seal undergoes complex changes with the increase of axial *** are two opposite vortices in the seal cavity with small axial gap,namely,the large vortex in the cavity and the small vortex near the wall of the *** small vortex gradually disappears with the increase of the axial *** the axial gap is increased to a certain value,the reverse large vortex is formed in the cavity behind the low teeth of seal,and the leakage rate increases significantly;the steam flow angle and the mixing loss also show different *** on the traditional calculation formula of tip leakage rate,a more accurate calculation formula of tip leakage rate is constructed by introducing equivalent labyrinth seal teeth to consider the variation of axial gap.

关键词： steam turbine axial gap tip leakage labyrinth seal prediction formulation

Element geochemical characteristics of a soil profile developed on dolostone in central Guizhou, southern China: implications for parent materials

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Acta Geochimica 2016年第4期35卷 445-462页

作者： Xingxing cao Pan Wu Zhenxing cao College of Resource and Environmental Engineering Guizhou University Graduate School of Science and Technology Shizuoka University

This study presents bulk chemical compositions of the Tongmuling soil profile, which developed on dolostone, and the overlying strata covering the bedrock in the central Guizhou province(southern China). The chemical weathering characteristics of the studied profile were investigated and the inheritance relationships between the terra rossa and overlying strata were discussed. The results show that there is no remarkable variation in the major elements and weathering indices from the rock–soil interface to the topsoil, indicating that the studied profile was not typical for in situ crustal chemical weathering. The terra rossa were mainly composed of Si O_2, Al_2O_3 and Fe_2O_3. Compared with the insoluble residues and overlying strata, the terra rossa are characterized by an enrichment of Y and Cs and depletion of Ba and Sr. The subsoil shows a notable Ce negative anomaly, characterized by heavy rare earth element enrichment(L/H = 1.55–3.74), whereas the topsoil shows a positive Ce anomaly with light rare earth element enrichment(L/H = 5.93–9.14). According to Laterite-forming capacity estimates, the terra rossa could not have only been formed from acid-insoluble residues from the bedrock; Al_2O_3 versus Fe_2O_3and Nb plotted against Ta show significant positive correlations between the terra rossa and overlying strata. The Eu/Eu* versusGd_N/Yb_Nand ternary diagrams for Sc, Th, Zr, and Ta suggest that the overlying strata could also provide parent materials for the genesis of terra rossa.

关键词： Terra rossa Dolomite Parent materials Guizhou China

Neural-Network-Based Nonlinear Model Predictive Tracking Control of a Pneumatic Muscle Actuator-Driven Exoskeleton

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IEEE/CAA Journal of Automatica Sinica 2020年第6期7卷 1478-1488页

作者： Yu cao Jian Huang IEEE Key Laboratory of Image Processing and Intelligent Control School of Artificial Intelligence and AutomationHuazhong University of Science and TechnologyWuhan 430074China

Pneumatic muscle actuators(PMAs)are compliant and suitable for robotic devices that have been shown to be effective in assisting patients with neurologic injuries,such as strokes,spinal cord injuries,etc.,to accomplish rehabilitation ***,because PMAs have nonlinearities,hysteresis,and uncertainties,etc.,complex mechanisms are rarely involved in the study of PMA-driven robotic *** this paper,we use nonlinear model predictive control(NMPC)and an extension of the echo state network called an echo state Gaussian process(ESGP)to design a tracking controller for a PMA-driven lower limb *** dynamics of the system include the PMA actuation and mechanism of the leg orthoses;thus,the system is represented by two nonlinear uncertain *** facilitate the design of the controller,joint angles of leg orthoses are forecasted based on the universal approximation ability of the ESGP.A gradient descent algorithm is employed to solve the optimization problem and generate the control *** stability of the closed-loop system is guaranteed when the ESGP is capable of approximating system *** and experiments are conducted to verify the approximation ability of the ESGP and achieve gait pattern training with four healthy subjects.

关键词： Echo state Gaussian process model predictive control neural network pneumatic muscle actuators-driven exoskeleton

Vibration-induced nanoscale friction modulation on piezoelectric materials

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Friction 2022年第10期10卷 1650-1659页

作者： Jiawei cao Qunyang LI Applied Mechanics Laboratory Department of Engineering MechanicsTsinghua UniversityBeijing 100084China State Key Laboratory of Tribology Tsinghua UniversityBeijing 100084China

Mechanical vibration,as an alternative of application of solid/liquid lubricants,has been an effective means to modulate friction at the ***,atomic force microscopy(AFM)experiments and model simulations also suggest a similar vibration-induced friction reduction effect for nanoscale contact interfaces,although an additional external vibration source is typically needed to excite the ***,by introducing a piezoelectric thin film along the contact interface,we demonstrate that friction measured by a conductive AFM probe can be significantly reduced(more than 70%)when an alternating current(AC)voltage is *** real-time friction modulation is achieved owing to the localized nanoscale vibration originating from the intrinsic inverse piezoelectric effect,and is applicable for various material *** by analysis with the Prandtl–Tomlinson(P–T)friction model,our experimental results suggest that there exists an approximately linear correlation between the vibrational amplitude and the relative factor for perturbation of sliding energy *** work offers a viable strategy for realizing active friction modulation for small-scale interfaces without the need of additional vibration source or global excitation that may adversely impact device functionalities.

关键词： vibration friction modulation piezoelectric materials contact resonance Prandtl-Tomlinson(P-T)model

氮、镁交互作用对杉木幼苗生长和生理特性的影响

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福建农林大学学报（自然科学版） 2025年第1期54卷 36-46页

作者：孟芳芳关恒锋杨浩许祖元左晓东曹光球曹世江福建农林大学林学院/国家林业和草原局杉木工程技术研究中心/福建农林大学林木逆境生理生态及分子生物学福建省高校重点实验室福建福州350002

【目的】探究氮、镁交互作用对杉木幼苗生长和生理特性的影响,确定适合杉木幼苗生长的氮、镁用量。【方法】以1年生杉木品种'青杉’幼苗为材料,采用盆栽法,设置氮三因素[0(N_(0))、1.2(N_(1))、2.4(N_(2))g·株^(-1)]、镁三水平[0(M_(0)... 详细信息

【目的】探究氮、镁交互作用对杉木幼苗生长和生理特性的影响,确定适合杉木幼苗生长的氮、镁用量。【方法】以1年生杉木品种'青杉’幼苗为材料,采用盆栽法,设置氮三因素[0(N_(0))、1.2(N_(1))、2.4(N_(2))g·株^(-1)]、镁三水平[0(M_(0))、0.64(M_(1))、1.28(M_(2))g·株-1]共9个处理,分别于施肥后的30、60、90、120、150、180 d测定各处理杉木幼苗的苗高、地径、叶绿素含量、可溶性蛋白含量、丙二醛(MDA)浓度、超氧化物歧化酶(SOD)活性、过氧化物酶(POD)活性和过氧化氢酶(CAT)活性等指标。【结果】(1)整个试验期间,杉木幼苗的苗高、地径增长量随着氮、镁用量的增加呈先上升后下降的趋势,N_(1)M_(1)处理的苗高、地径增长量显著大于N_(0)M_(0)处理(P<0.05)。(2)整个试验期间,随着氮、镁用量的增加,叶绿素含量整体呈先下降后上升的趋势,可溶性蛋白含量整体呈先上升后逐渐趋于稳定的趋势,MDA浓度、SOD活性整体呈先上升后下降的趋势,POD活性、CAT活性整体呈先下降后上升的趋势。(3)整个试验期间,N_(1)M_(1)处理的叶绿素含量显著大于N_(0)M_(0)处理(P<0.05);N_(1)M_(1)处理的MDA浓度在多数情况下最低;N_(1)M_(1)处理的POD活性显著大于N_(0)M_(0)处理(P<0.05),且大于N_(2)M_(1)、N_(1)M_(2)、N_(2)M_(2)处理;处理60~150 d时,SOD活性整体变化较平稳,N_(1)M_(1)处理的CAT活性大于N_(0)M_(0)处理。【结论】氮、镁交互作用处理N_(1)M_(1)可降低细胞膜的损害程度,提高细胞渗透调节能力,增强细胞抗氧化酶活性,促进杉木幼苗生长发育。

关键词：杉木氮镁交互抗氧化酶生长特性生理特性

Weak rigid monoidal category

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Frontiers of Mathematics in China 2017年第1期12卷 19-33页

作者： Haijun cao School of Science Shandong Jiaotong University Jinan 250375 China

We define the right regular dual of an object X in a monoidal category l, and give several results regarding the weak rigid monoidal category. Based on the definition of the right regular dual, we construct a weak Hopf algebra structure of H = End（F） whenever （F, J） is a fiber functor from category l to Vec and every X ∈ l has a right regular dual. To conclude, we give a weak reconstruction theorem for a kind of weak Hopf algebra.

关键词： Semilattice graded weak Hopf algebra regular right dual weak rigid monoidal category