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A functional tacrolimus-releasing nerve wrap for enhancing nerve regeneration following surgical nerve repair

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Neural Regeneration Research 2025年第1期20卷 291-304页

作者： Simeon c.Daeschler Katelyn J.W.So Konstantin Feinberg Marina Manoraj Jenny cheung Jennifer Zhang Kaveh Mirmoeini JPaul Santerre Tessa Gordon Gregory hBorschel SickKids Research Institute Neuroscience and Mental Health ProgramTorontoONCanada Institute of Biomaterials and Biomedical Engineering University of TorontoTorontoONCanada Indiana University School of Medicine IndianapolisINUSA Division of Plastic and Reconstructive Surgery the Hospital for Sick ChildrenTorontoONCanada Translational Biology and Engineering Program Ted Rogers Centre for Heart ResearchInstitute of Biomedical EngineeringFaculty of DentistryUniversity of TorontoTorontoONCanada

Axonal regeneration following surgical nerve repair is slow and often incomplete,resulting in poor functional recovery which sometimes contributes to lifelong ***,there are no FDA-approved therapies available to promote nerve *** accelerates axonal regeneration,but systemic side effects presently outweigh its potential benefits for peripheral nerve *** authors describe herein a biodegradable polyurethane-based drug delivery system for the sustained local release of tacrolimus at the nerve repair site,with suitable properties for scalable production and clinical application,aiming to promote nerve regeneration and functional recovery with minimal systemic drug *** is encapsulated into co-axially electrospun polycarbonate-urethane nanofibers to generate an implantable nerve wrap that releases therapeutic doses of bioactive tacrolimus over 31 *** and drug loading are adjustable for applications in small and large caliber nerves,and the wrap degrades within 120 days into biocompatible *** released from the nerve wrap promotes axon elongation in vitro and accelerates nerve regeneration and functional recovery in preclinical nerve repair models while off-target systemic drug exposure is reduced by 80%compared with systemic *** its surgical suitability and preclinical efficacy and safety,this system may provide a readily translatable approach to support axonal regeneration and recovery in patients undergoing nerve surgery.

关键词： biodegradable local drug delivery nerve injury nerve regeneration nerve wrap tacrolimus

Formation of TiN Grid on NiTi by Laser Gas Nitriding for Improving Wear Resistance in hanks' Solution

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Journal of Materials Science & Technology 2016年第5期32卷 459-464页

作者： c.h.Ng O.K.chan h.c.Man Department of Industrial and Systems Engineering The Hong Kong Polytechnic University

Laser gas nitriding （LGN） is a common surface modification method to enhance the wear resistance of titanium （Ti） alloys, which are known to have poor tribological properties. In the present study, a titanium nitride （TIN） grid network was fabricated on the surface of nickel titanium （NiTi） by LGN. The laser processing parameters were selected to achieve nitriding without surface melting and hence to＇maintain a smooth surface finish. The characteristics of the grid-nitrided samples were investigated by scanningelectron microscopy, X-ray diffractometry, optical microscopy, 2-D profilometry, contact angle measurements and nanoindentation. The wear resistance of the nitrided samples was evaluated using reciprocating wear test against ultra-high-molecular-weight polyethylene （UhMWPE） in hanks＇ solution. The results indicate that the wear rates of the grid-nitrided samples and the UhMWPE counter-body in the wear pair are both significantly reduced. The decrease in wear rates can be attributed to the combination of a hard TiN grid and a soft NiTi substrate. In hanks＇ solution, the higher hydrophilicity of the nitrided samples also contributes to the better performance in wear test against hydrophobic UhMWPE.

关键词： Laser Nitriding Surface patterning Titanium alloys Wear

Numerical simulation and experimental study for rheo-forged component using direct and indirect die system

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Transactions of Nonferrous Metals Society of china 2010年第9期20卷 1799-1804页

作者： h.h.KIM c.G.KANG Precision Manufacturing Systems Division Pusan National University School of Mechanical Engineering Pusan National University

Sand casting and die casting processes have been used widely for complex automotive products such as knuckle, arm, ***, a part fabricated by casting has limited strength due to manufacturing defects such as the dendrite structure, segregation and *** an attempt to offer a solution to these problems, forging has been used as an alternative ***, the forging process provides limited formability for complex shape ***-forging of metal offers not only superior mechanical strength but also requires significantly lower machine loads than solid forming *** order to produce semi-solid materials of the desired microstructure, a stirring process is applied during solidification of molten *** results of an A356 aluminum alloy sample, which are obtained by experiment and by simulation using DEFORM 3D, are present.

关键词： rheo-forging A356 alloy formability forming defects

Temperature and Thermal Stress Distribution for Metal Mold in Squeeze casting Process

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Journal of Materials Science & Technology 2008年第3期24卷 347-350页

作者： c.h.Lee S.h.Lee Institute of Technology and Science Chung-Ang University

In the squeeze casting process, loaded high pressure （over approximately 200 MPa） and high temperature influence the thermo-mechanical behavior and performance of the used metal mold. Therefore, to safely maintain the metal molds, the thermo-mechanical characteristics （temperature and thermal stress） of metal mold in the squeeze casting must be investigated. In this paper, temperature and thermal stress distribution of steel mold in squeeze casting process were investigated by using a three-dimensional non-steady heat conduction analysis and a three-dimensional thermal elastic-plastic analysis considering temperature-dependent thermophysical and mechanical properties of the steel mold.

关键词： Squeeze casting Steel mold Thermal stress Thermo-Mechanical analysis

Roles of soil-structure interaction and damping in base-isolated structures built on numerous soil layers overlying a half-space

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Earthquake Engineering and Engineering Vibration 2016年第2期15卷 387-400页

作者： c.S.Tsai c.I.hsueh h.c.Su Department of civil Engineering Feng Chia University Graduate Institute of civil & hydraulic Engineering Feng Chia University Department of Water Resources Engineering and conservation Feng Chia University

This study examines the roles of soil-structure interaction （SSI）, higher modes, and damping in a base-isolated structure built on multiple layers of soil overlying a half space. closed-form solutions for the entire system, including a superstructure, seismic isolator, and numerous soil layers overlying a half-space, were obtained. The formulations obtained in this study simply in terms of well-known frequencies and mechanical impedance ratios can explicitly interpret the dynamic behavior of a base-isolated structure interacting with multiple soil layers overlying a half-space. The key factors influencing the performance of the isolation system are the damping ratio of the isolator and the ratio of the natural frequency of the fixed-base structure to that of the isolated structure by assuming that the superstructure moves as a rigid body. This study reveals that higher damping in the base isolator is unfavorable to higher mode responses that usually dominate the responses of the superstructure and that the damping mechanism plays an important role in transmitting energy in addition to absorbing energy. It is also concluded that it is possible to design a soft soil layer as an isolation system for isolating vibration energy.

关键词： base isolation seismic isolation soil-structure interaction closed- form solution higher-mode effects soilstratum passive control damping effects

Equivalent series system to model a multiple friction pendulum system with numerous sliding interfaces for seismic analyses

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Earthquake Engineering and Engineering Vibration 2014年第1期13卷 85-99页

作者： c.S.Tsai h.c.Su T.c.chiang Department of civil Engineering Feng Chia University Department of Water Resources Engineering and conservation Feng Chia University Earthquake Proof Systems Inc.

current structural analysis software programs offer few if any applicable device-specifi c hysteresis rules or nonlinear elements to simulate the precise mechanical behavior of a multiple friction pendulum system(MFPS) with numerous sliding *** on the concept of subsystems,an equivalent series system that adopts existing nonlinear elements with parameters systematically calculated and mathematically proven through rigorous derivations is *** aim is to simulate the characteristics of sliding motions for an MFPS isolation system with numerous concave sliding interfaces without prior knowledge of detailed information on the mobilized forces at various sliding *** MFPS with numerous concave sliding interfaces and one articulated or rigid slider located between these interfaces is divided into two subsystems: the fi rst represents the concave sliding interfaces above the slider,and the second represents those below the *** equivalent series system for the entire system is then obtained by connecting those for each subsystem in *** equivalent series system is validated by comparing numerical results for an MFPS with four sliding interfaces obtained from the proposed method with those from a previous study by Fenz and ***,these numerical results demonstrate that an MFPS isolator with numerous concave sliding interfaces,which may have any number of sliding interfaces,is a good isolation device to protect structures from earthquake damage through appropriate designs with controllable mechanisms.

关键词： seismic isolation base isolation earthquake engineering multiple friction pendulum system structural control mathematical modeling equivalent series system

TENSILE cREEP DEFORMATION AND DAMAGE BEhAVIOR IN A NIcKEL-BASE SUPERALLOY AT 900℃

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Acta Metallurgica Sinica(English Letters) 2004年第4期17卷 606-611页

作者： h.c.Yu S.S.Xie h.c.Yang Beijing Institute of Aeronautical Materials Beijing 100095 ChinaR & D Center Baosteel Co. Ltd. Shanghai 201900 ChinaCollege of Materials and Metallurgy Northeastern University Shenyang 110004 China

The tensile creep deformation and damage evolution in a Ni-base superalloy at 900℃/170MPa were investigated. At the first creep stage, abnormal creep occured due to the resolution of fine particles, and the deformation initiated from grain boundary areas. It is evident that nearly all of the dislocations were in γ matrix channels in form of dislocation pairs and the dislocations were impeded at γ/γ' interfaces, thus the dislocation networks developed deformation. At the steady creep stage, impeded dislocations atγ/γ' interfaces climbed over γ' phases by diffusion-dominant mechanism. At the last creep stage, voids were formed around carbides at grain boundary which leaded to accumulated damage and caused creep rate accelerated. With the dislocation networks being broken, the voids connected and grew into micro-cracks gradually. Finally the cracks propagated along grain boundary area and resulted in failure.

关键词： creep deformation and damage dislocation microstructure su-peralloy