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Silk-based nerve guidance conduits with macroscopic holes modulate the vascularization of regenerating rat sciatic nerve

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Neural Regeneration Research 2025年第6期20卷 1789-1800页

作者： Carina hromada Patrick heimel Markus Kerbl lászlóGál Sylvia Nürnberger barbara Schaedl James Ferguson Nicole Swiadek Xavier Monforte Johannes C.heinzel Antal Nógrádi Andreas h.Teuschl-Woller David hercher Department life Science Engineering University of Applied Sciences Technikum WienViennaAustria Austrian Cluster for Tissue Regeneration ViennaAustria ludwig boltzmann Institute for Traumatology The Research Center in Cooperation with AUVAViennaAustria University Clinic of Dentistry Medical University of ViennaViennaAustria Department of Plastic Reconstructive and Aesthetic SurgeryLandesklinikum Wiener Neustadt2700 Wiener NeustadtAustria Department of Anatomy Histology and EmbryologyAlbert Szent-Györgyi Medical SchoolUniversity of SzegedSzegedHungary Medical University of Vienna Department of Orthopedics and Trauma SurgeryDevision of Trauma SurgeryViennaAustria Department of hand- PlasticReconstructive and Burn SurgeryBG Unfallklinik TuebingenUniversity of TuebingenTuebingenGermany

Peripheral nerve injuries induce a severe motor and sensory deficit. Since the availability of autologous nerve transplants for nerve repair is very limited, alternative treatment strategies are sought, including the use of tubular nerve guidance conduits(tNGCs). however, the use of tNGCs results in poor functional recovery and central necrosis of the regenerating tissue, which limits their application to short nerve lesion defects(typically shorter than 3 cm). Given the importance of vascularization in nerve regeneration, we hypothesized that enabling the growth of blood vessels from the surrounding tissue into the regenerating nerve within the tNGC would help eliminate necrotic processes and lead to improved regeneration. In this study, we reported the application of macroscopic holes into the tubular walls of silk-based tNGCs and compared the various features of these improved silk^(+) tNGCs with the tubes without holes(silk^(–) tNGCs) and autologous nerve transplants in an 8-mm sciatic nerve defect in rats. Using a combination of micro-computed tomography and histological analyses, we were able to prove that the use of silk^(+) tNGCs induced the growth of blood vessels from the adjacent tissue to the intraluminal neovascular formation. A significantly higher number of blood vessels in the silk^(+) group was found compared with autologous nerve transplants and silk^(–), accompanied by improved axon regeneration at the distal coaptation point compared with the silk^(–) tNGCs at 7 weeks postoperatively. In the 15-mm(critical size) sciatic nerve defect model, we again observed a distinct ingrowth of blood vessels through the tubular walls of silk^(+) tNGCs, but without improved functional recovery at 12 weeks postoperatively. Our data proves that macroporous tNGCs increase the vascular supply of regenerating nerves and facilitate improved axonal regeneration in a short-defect model but not in a critical-size defect model. This study suggests that further optimizatio

关键词： axon regeneration blood vessel functional recovery macroporous nerve lesion peripheral nerve repair sciatic nerve silk-based nerve guidance conduit vascularization

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Melting, Oxidation, Evaporation of Particle in-Flight in Plasma Spray Processes

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Journal of Materials Science & Technology 2003年第z1期19卷 49-52页

作者： h.b.Xiong l.l.Zheng Department of Mechanical Engineering State University of New York at Stony Brook Stony Brook NY 11794-2300 USA Department of Mechanical Engineering State University of New York at Stony Brook Stony Brook NY 11794-2300 USA

A comprehensive numerical model has been developed to investigate the transient behaviors of particle characteristics, such as temperature, melting, evaporation, and oxidation status during argon-hydrogen DC plasma *** model includes heat, momentum and mass transfer of carrier gas, and particle heating, melting, evaporationand oxidation. Special attentions have been paid to the evaporation-induced mass transfer and oxidation-inducedevaporation as well as variable non-continuum phenomena.

关键词： Melting, Oxidation, Materials processing, Multi-components reacting flow, Computational heat transfer

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Reactivity of Nanostructured MnO_2 in Alkaline Medium Studied with a Microcavity Electrode: Effect of Oxidizing Agent

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Journal of Materials Science & Technology 2011年第7期27卷 585-593页

作者： l.benhaddad l.Makhloufi b.Messaoudi1 K.Rahmouni h.Takenouti laboratoire de Technologie des Matériaux et Génie des Procédés (lTMGP) Département de Génie des Procédés. Université A. MiraRoute de Targa Ouzemmour06000 BéjaiaAlgeria UPR 15 du CNRS lISE-laboratoire Interfaces et Systèmes Electrochimiques UPMC University Paris 06Case 133 4 place Jussieu 75252 Paris Cedex 05 France UPR 15 du CNRS lISE-laboratoire Interfaces et Systèmes Electrochimiques UPMC University Paris 06Case 1334 place Jussieu 75252 Paris Cedex 05France

The synthesis of MnO2 powders by hydrothermal method with different oxidizing agents has been successfully achieved. The characterizations by scanning electron microscopy, energy-dispersive X-ray analyses, transmission electron microscopy, and X-ray diffraction techniques confirm the synthesis of nanostructured γ-MnO2 powders. The electrochemical reactivity of these powders in 1 mol/l KOh is investigated by cyclic voltammetry and electrochemical impedance spectroscopy （EIS） by using microcavity electrode. The results reveal that the MnO2 synthesized with Na2S2O8 shows the highest electrochemical reactivity in the test medium. This is due both to its large expanded surface area and its crystallographic variety γ-MnO2 formed in the matrix of ramsdellite, which is largely used as cathodic material for primary batteries. however, the presence of pyrolusite in the structure of γ-MnO2 synthesized with （Nh4）2S2O8 decreases its electrochemical reactivity due to its narrow 1×1 size tunnel, which hinders the protons insertion.

关键词： hydrothermal processing Electrochemical impedance spectroscopy (EIS) Cyclic voltammetry X-ray diffraction γ-MnO2

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Static spheroidization and its effect on superplasticity of fine lamellae in nugget of a friction stir welded Ti-6Al-4V joint

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Journal of Materials Science & Technology 2022年第24期119卷 1-10页

作者： C.l.Jia l.h.Wu P.Xue h.Zhang D.R.Ni b.l.Xiao Z.Y.Ma Shi-Changxu Innovation Center for Advanced Materials Institute of Metal ResearchChinese Academy of SciencesShenyang 110016China School of Materials Science and Engineering University of Science and Technology of ChinaShenyang 110016China Key laboratory of Nuclear Materials and Safety Assessment Institute of Metal ResearchChinese Academy of SciencesShenyang 110016China

The spheroidization of the lamellar structure can greatly contribute to the superplasticity of the nugget zone(NZ)of Ti alloy welds,which is the key to achieve the integral superplastic forming of welds for the fabrication of large-scale complex ***,the spheroidization process is complex and costly since it cannot be obtained generally,unless the lamellae suffers from a large *** this study,the static spheroidization was achieved for the fine lamellae structure in the nugget of a friction stir welded(FSW)Ti-6Al-4V joint,particularly by the annealing without any *** specialα/βinterface obeying a burgers orientation relationship(bOR)after FSW was first time directly observed,whose effect on the spheroidization was discussed.A new static spheroidization mechanism with the gradual coalescence of the adjacent lamellae was discovered,which we named as“termination coalescence”.There was a slower coarsening rate in the lamellar structure than in the classical equiaxed one,due to the bOR in the lamellae,although both of them exhibited a volume diffusion character during ***,the similar superplasticity can be achieved for the base material and NZ after *** study can provide a new way to the spheroidization and a theoretical basis for the integral superplastic forming of welds during production.

关键词： Friction stir welding Titanium alloys Spheroidization mechanism Coalescence Superplasticity Static annealing

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Microstructures and Mechanical Properties of Vacuum brazed Ti3Al/TiAl Joints Using Two Ti-based Filler Metals

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Journal of Materials Science & Technology 2016年第4期32卷 372-380页

作者： h.S.Ren h.P.Xiong b.Chen S.J.Pang b.Q.Chen l.Ye Department of Material Science and Engineering Beihang University Beijing 100191 China Welding and Plastic Forming Division Beijing Institute of Aeronautical Materials Beijing 100095 China

Vacuum brazing of Ti3Al-based alloy to TiAI was firstly carried out by Ti-15Cu-15Ni （wt%） filler metal. A continuous Ti3Al band, Ti2Ni and Ti2Cu/Cu3Ti phases formed and the joint showed a shear strength of 53.8-112.4 MPa at room temperature. For the improvement of the joint strength, a new Ti--Zr--Cu--Ni--Fe filler alloy was designed, and its wettability on Ti3AI and TiA1 substrate was studied with the sessile drop method. After holding for 20 rain at 1010 ℃ the Ti--Zr--Cu--Ni--Fe filler showed a low contact angle of 20° and 21° on Ti3Al and TiAI substrate, respectively. The joint brazed with this novel filler mainly con- sisted of Ti-rich area, Ti3Al reaction layer and residual filler metal. With the increase of the brazing temperature, the amount of residual filler metal decreased and the TisAl reaction layer thickened. The Ti3Al/TiA1 joint brazed with Ti--Zr--Cu--Ni--Fe filler exhibited a lower hardness than that brazed with Ti--Cu--Ni filler. The corresponding joints brazed at 950 ℃ for 5 min presented the shear strength of 257.6± 33.6 MPa at room temperature and 304.8 ± 9.9 MPa at 600 ℃.

关键词： brazingTitanium aluminidesMicrostructureShear strength

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A stabilized complementarity formulation for nonlinear analysis of 3D bimodular materials

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Acta Mechanica Sinica 2016年第3期32卷 481-490页

作者： l.Zhang h.W.Zhang J.Wu b.Yan Department of Engineering Mechanics College of AerospaceEngineering Chongqing University State Key laboratory of Structural Analysis for IndustrialEquipment Dalian University of Technology

bi-modulus materials with different mechanical responses in tension and compression are often found in civil,composite, and biological engineering. Numerical analysis of bimodular materials is strongly nonlinear and convergence is usually a problem for traditional iterative schemes. This paper aims to develop a stabilized computational method for nonlinear analysis of 3D bimodular materials. based on the parametric variational principle, a unified constitutive equation of 3D bimodular materials is proposed, which allows the eight principal stress states to be indicated by three parametric variables introduced in the principal stress *** original problem is transformed into a standard linear complementarity problem（lCP） by the parametric virtual work principle and a quadratic programming algorithm is developed by solving the lCP with the classic lemke＇s algorithm. Update of elasticity and stiffness matrices is avoided and, thus, the proposed algorithm shows an excellent convergence behavior compared with traditional iterative *** examples show that the proposed method is valid and can accurately analyze mechanical responses of 3D bimodular materials. Also, stability of the algorithm is greatly improved.

关键词： bimodular materials Non-smooth stressstrain relationship Parametric variational principle Complementarity

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Corrosion protection investigations of carbon dots and polydopamine composite coating on magnesium alloy

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Journal of Magnesium and Alloys 2022年第5期10卷 1358-1367页

作者： h.D.Zhang A.Y.Chen b.Gan h.Jiang l.J.Gu School of Material Science&Engineering University of Shanghai for Science and TechnologyShanghai 200093China beijing Key laboratory of Advanced high Temperature Materials Central Iron and Steel Research InstituteBeijing 100081China

A composite coating of nitrogen-doped carbon dots(N–CDs)and polydopamine(PDA)was prepared on magnesium alloy by combining electrodeposition with dip coating *** microstructure of the N–CDs/PDA composite coating,including composition,surface morphology,and crystalline structure,is characterized by Raman spectroscopy,scanning electron microscopy,transmission electron microscopy,and X-ray photoelectron spectroscopy,*** corrosion protection performances of the composite coating are evaluated by potentiodynamic polarization tests,electrochemical impedance spectroscopy,and salt spray *** effect of the particle size of the N–CDs on the corrosion performance is also *** results show that the corrosion performance of the N–CDs coatings are enhanced with the increase of the particle ***,an obvious self-healing performance is observed on the surface of the N–CDs/PDA composite *** results indicate that N–CDs/PDA composite coating can improve the corrosion performance of the Mg alloy,and open a new design direction for the protective coating of metallic materials.

关键词： Magnesium alloy N-doped carbon dots Particle size Dopamine Coating Corrosion resistance

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Quantitative law of diffusion induced fracture

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Acta Mechanica Sinica 2016年第4期32卷 611-632页

作者： h.-J.lei h.-l.Wang b.liu C.-A.Wang AMl CNMMDepartment of Engineering MechanicsTsinghua UniversityBeijing 100084China State Key lab of New Ceramics and Fine Processing Department of Materials Science and EngineeringTsinghua UniversityBeijing 100084China

Through dimension analysis, an almost analytical model for the maximum diffusion induced stress（DIS）and critical temperature（or concentration） difference at which cracks begin to initiate in the diffusion process is developed. It interestingly predicts that the spacing of diffusioninduced cracks is constant, independent of the thickness of specimen and the temperature difference. These conclusions are validated by our thermal shock experiments on alumina plates. Furthermore, the proposed model can interpret observed hierarchical crack patterns for high temperature jump cases, and a three-stage relation between the residual strength and the temperature difference. The prediction for crack spacing can guide the biomimetic thermal-shockfailure proof design, in which the hard platelets smaller than the predicted diffusion induced by constant crack-spacing are embedded in a soft matrix, and, therefore, no fracture will happen. This may guide the design of the thermal protection system and the lithium ion battery. Finally we present the maximum normalized DISes for various geometry and boundary conditions by single-variable curves for the stressindependent diffusion process and two-variable contour plots for the stress-dependent diffusion process, which can provideengineers and materialists a simple and easy way to quickly evaluate the reliability of related materials and devices.

关键词： normalized hierarchical contour spacing quickly lithium validated battery constraint coordinate

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Effect of two-step cooling process on mechanical properties of TRIP steel with high performance

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Journal of Iron and Steel Research International 2018年第4期25卷 426-432页

作者： M.l. li h. Jiang Y.l. he l.b. Chen G.T. Zhang h. Wang X.G. lu l. li School of Materials Science and Engineering Shanghai University Shanghai 200072 China State Key laboratory of Advanced Special Steel Shanghai University Shanghai 200072 China Pangang Group Research Institute Panzhihua 617000 Sichuan China

A novel two-step cooling experiment was established to simulate the slow cooling process of continuous annealing production line for transformation-induced plasticity （TRIP） steel. The microstructures and mechanical properties of TRIP steel soaked at 700℃ for different time were investigated by tensile test, scanning electron microscopy, X-ray diffraction, and thermodynamic and kinetic calculation. It is shown that the steel soaked for 15 s exhibits the optimal product of strength and elongation （PSE 〉 30,000 MPa%） due to the transformation of austenite to proeutectoid ferrite, which delays the bainite transformation and improves the stability of retained austenite. In addition, the mechanical properties of TRIP steel soaked over 30 s are much lower, resulting from the precipitation of cementite, which decreases the stability of retained austenite and weakens the TRIP effect.

关键词： Transformation induced plasticity steel Two-step cooling Microstructure Mechanical property

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Mechanical properties of gas hydrate-bearing sediments during hydrate dissociation

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Acta Mechanica Sinica 2018年第2期34卷 266-274页

作者： X.h.Zhang D.S.luo X.b.lu l.l.liu C.l.liu Institute of Mechanics Chinese Academy of SciencesBeijing 100190China College of Engineering University of Chinese Academy of SciencesBeijing 100049China Key laboratory of Gas hydrate Ministry of Land and ResourcesQingdao 266071China Qingdao Institute of Marine Geology Qingdao 266071China

The changes in the mechanical properties of gas hydrate-bearing sediments(GhbS) induced by gas hydrate(Gh) dissociation are essential to the evaluation of Gh exploration and stratum instabilities. Previous studies present substantial mechanical data and constitutive models for GhbS at a given Gh saturation under the non-dissociated condition. In this paper, GhbS was formed by the gas saturated method, Gh was dissociated by depressurization until the Gh saturation reached different dissociation degrees. The stress–strain curves were measured using triaxial tests at a same pore gas pressure and different confining pressures. The results show that the shear strength decreases progressively by 30%–90% of the initial value with Gh dissociation, and the modulus decreases by 50% –75%. Simplified relationships for the modulus, cohesion, and internal friction angle with Gh dissociated saturation were presented.

关键词： Gas hydrate-bearing sediments Dissociation Mechanical properties Shear strength Triaxial test

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