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Linking the effect of localised pitting corrosion with mechanical integrity of a rare earth magnesium alloy for implant use

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Bioactive Materials 2023年第3期21卷 32-43页

作者： Kerstin van Gaalen Conall Quinn Felix Benn Peter E.McHugh alexander kopp Ted J.Vaughan Biomechanics Research Centre(BioMEC) Biomedical EngineeringSchool of EngineeringNational University of Ireland GalwayGalwayIreland Meotec GmbH AachenGermany School of Mechanical and Aerospace Engineering Queen’s University BelfastBelfastUnited Kingdom

This study presents a computational framework that investigates the effect of localised surface-based corrosion on the mechanical performance of a magnesium-based alloy.A finite element-based phenomenological corrosion model was used to generate a wide range of corrosion profiles,with subsequent uniaxial tensile test simulations to predict the mechanical response to *** python-based detection framework PitScan provides detailed quantification of the spatial phenomenological features of corrosion,including a full geometric tracking of corroding *** this approach,this study is the first to quantitatively demonstrate that a surface-based non-uniform corrosion model can capture both the geometrical and mechanical features of a magne-sium alloy undergoing corrosion by comparing to experimental *** this verified corrosion modelling approach,a wide range of corrosion scenarios was evaluated and enabled quantitative relationships to be established between the mechanical integrity and key phenomenological corrosion *** particular,we demonstrated that the minimal cross-sectional area parameter was the strongest predictor of the remaining mechanical strength(R2=0.98),with this relationship being independent of the severity or spatial features of localised surface ***,our analysis demonstrated that parameters described in ASTM G46-94 showed weaker correlations to the mechanical integrity of corroding specimens,compared to parameters determined by *** study establishes new mechanistic insight into the performance of the magnesium-based materials undergoing corrosion.

关键词： Magnesium Localised corrosion Corrosion modelling Phenomenology FEM

Automated ex-situ detection of pitting corrosion and its effect on the mechanical integrity of rare earth magnesium alloy-WE43

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Bioactive Materials 2022年第2期7卷 545-558页

作者： Kerstin van Gaalen Felix Gremse Felix Benn Peter E.McHugh alexander kopp Ted J.Vaughan Biomechanics Research Centre(BioMEC) Biomedical EngineeringSchool of EngineeringCollege of Science and EngineeringNational University of Ireland GalwayGalwayIreland Meotec GmbH AachenGermany Institute for Experimental Molecular Imaging RWTH Aachen UniversityAachenGermany School of Mechanical and Aerospace Engineering Queen’s University BelfastBelfastUnited Kingdom

This study develops a three-dimensional automated detection framework(PitScan)that systematically evaluates the severity and phenomenology of pitting *** framework uses a python-based algorithm to analyse microcomputer-tomography scans(μCT)of cylindrical specimens undergoing *** approach systematically identifies several surface-based corrosion features,enabling full spatial characterisation of pitting parameters,including pit density,pit size,pit depth as well as pitting factor according to ASTM ***,it is used to evaluate pitting formation in tensile specimens of a Rare Earth Magnesium alloy undergoing corrosion,and relationships between key pitting parameters and mechanical performance are *** demonstrated that several of the parameters described in ASTM G46-94,including pit number,pit density and pitting factor,showed little correlation to mechanical ***,this study did identify that other parameters showed strong correlations with the ultimate tensile strength and these tended to be directly linked to the reduction of the cross-sectional area of the ***,our results indicate,that parameters directly linked to the loss of the cross-sectional area(*** material width),are parameters that are most suited to provide an indication of a specimen’s mechanical *** automated detection framework developed in this study has the potential to provide a basis to standardise measurements of pitting corrosion across a range of metals and future prediction of mechanical strength over degradation time.

关键词： Magnesium Corrosion Degradation Micro-computer-tomography Pit detection Automatization Mechanical integrity

Predicting localised corrosion and mechanical performance of a PEO surface modified rare earth magnesium alloy for implant use through in-silico modelling

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Bioactive Materials 2023年第8期26卷 437-451页

作者： Kerstin van Gaalen Conall Quinn Marek Weiler Felix Gremse Felix Benn Peter E.McHugh Ted J.Vaughan alexander kopp Biomechanics Research Centre(BioMEC) Biomedical EngineeringSchool of EngineeringUniversity of GalwayGalwayIreland Meotec GmbH AachenGermany Institute for Experimental Molecular Imaging RWTH Aachen UniversityAachenGermany Gremse-IT GmbH AachenGermany School of Mechanical and Aerospace Engineering Queen’s University BelfastBelfastUnited Kingdom

In this study,the influence of a plasma electrolytic oxidation(PEO)surface treatment on a medical-grade WE43-based magnesium alloy is examined through an experimental and computational framework that considers the effects of localised corrosion features and mechanical properties throughout the corrosion ***,a comprehensive in-vitro immersion study was performed on WE43-based tensile specimens with and without PEO surface modification,which included fully automated spatial reconstruction of the phenomenological features of corrosion through micro-CT scanning,followed by uniaxial tensile *** the experimental data of both unmodified and PEO-modified groups were used to calibrate parameters of a finite element-based surface corrosion ***-vitro,it was found that the WE43-PEO modified group had a significantly lower corrosion rate and maintained significantly higher mechanical properties than the *** corrosion rates were~50%lower in the WE43-PEO modified specimens,the local geometric features of corroding surfaces remained similar to the unmodified WE43 group,however evolving after almost the double amount of *** were also able to quantitatively demonstrate that the PEO surface treatment on magnesium continued to protect samples from corrosion throughout the entire period tested,and not just in the early stages of *** the results from the testing framework,the model parameters of the surface-based corrosion model were identified for both *** enabled,for the first time,in-silico prediction of the physical features of corrosion and the mechanical performance of both unmodified and PEO modified magnesium *** simulation framework can enable future in-silico design and optimisation of bioabsorbable magnesium devices for load-bearing medical applications.

关键词： Plasma electrolytic oxidation WE43MEO Degradation model Corrosion phenomenology Mechanical integrity

Effect of process parameters on additive-free electrospinning of regenerated silk fibroin nonwovens

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Bioactive Materials 2020年第2期5卷 241-252页

作者： alexander kopp Ralf Smeets Martin Gosau Nadja Kröger Sandra Fuest Marius Köpf Magnus Kruse Judith Krieger Rico Rutkowski Anders Henningsen Simon Burg Fibrothelium GmbH AachenGermany Department of Oral and Maxillofacial Surgery University Medical Center Hamburg-EppendorfHamburgGermany Department of Oral and Maxillofacial Surgery Division of Regenerative Orofacial MedicineUniversity Medical Center Hamburg-EppendorfHamburgGermany Institut Fuer Textiltechnik of RWTH Aachen University AachenGermany Department of Oral and Maxillofacial Surgery German Armed Forces HospitalHamburgGermany Department of Plastic Reconstructive and Aesthetic SurgeryUniversity Hospital of CologneCologneGermany

Silk fibroin is a biomaterial with multiple beneficial properties for use in regenerative medicine and tissue *** dissolving and processing the reconstituted silk fibroin solution by electrospinning,the arrangement and size of fibers can be manifold varied and according fiber diameters reduced to the nanometer *** nonwovens show high porosity as well as potential ***,electrospinning of most biomaterials demands for the application of additives,which enable stable electrospinning by adjusting viscosity,and are intended to evaporate during processing or to be washed out ***,the use of such additives increases costs and has to be taken into account in terms of biological risks when used for biomedical *** this study,we explored the possibilities of additive-free electrospinning of pure fibroin nonwovens and tried to optimize process parameters to enable stable *** used natural silk derived from the mulberry silkworm Bombyx *** degumming,the silk fibroin was dissolved and the viscosity of the spinning solution was controlled by partial evaporation of the initial solving *** way,we were able to completely avoid the use of additives and manufacture nonwovens,which potentially offer higher biocompatibility and reduced *** and relative humidity during electrospinning were systematically varied(25–35°C,25–30%RH).In a second step,the nonwovens optionally underwent methanol treatment to initiate beta-sheet formation in order to increase structural integrity and *** surface analysis on the different nonwovens was performed using scanning electron microscopy and supplemented by additional mechanical *** was evaluated using BrdU-assay,XTT-assay,LDH-assay and live-dead *** findings were,that an increase of temperature and relative humidity led to unequal fiber diameters and defective *** to penetration decr

关键词： Fibroin Additive-free electrospinning Nanofiber Silk Scaffolds

世界家庭医生组织(WONCA)研究论文摘要汇编——急诊服务利用率与入住提供全天候服务的医疗之家之间的关系研究

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中国全科医学 2019年第1期22卷 116-116页

作者：本刊编辑部 KIRAN T MOINEDDIN R kopp alexander

目的与其他高收入国家相比,加拿大和美国的患者急诊服务利用率较高,而患者在工作时间外到全科医师处就诊的比例较低(全科医师报告)。本研究对初次入住得到授权提供全天候服务的加拿大安大略省医疗之家的患者进行分析,以探讨患者在接受... 详细信息

目的与其他高收入国家相比,加拿大和美国的患者急诊服务利用率较高,而患者在工作时间外到全科医师处就诊的比例较低(全科医师报告)。本研究对初次入住得到授权提供全天候服务的加拿大安大略省医疗之家的患者进行分析,以探讨患者在接受医疗之家服务后,急诊服务利用率是否有所降低。方法本研究为回顾性队列研究,资料来源于安大略省官方报告。以2005-04-01至2012-03-31入住医疗之家的安大略省成年患者为研究对象(n=2 945 087),均具有至少3年(入住医疗之家前后)的结局资料。以患者性别为固定变量,以年龄、收入水平(五分位法划分)、合并症及发病情况为时变协变量,建立分段线性回归模型,以探讨患者初次入住医疗之家对急诊就诊次数、周末全科就诊率、总体全科就诊率的影响。结果患者入住医疗之家前,急诊就诊率年均增长率为0.8%[95%CI(0.7%,0.9%)],入住医疗之家后为1.5%[95%CI(1.4%,1.5%)]。入住医疗之家后,患者的周末全科就诊率有所增加,但总体全科就诊率有所下降。结论安大略省成年患者入住提供全天候服务的医疗之家后,急诊服务的利用率并未下降。为提高常规工作时间之外提供的全科医疗服务可及性,有必要对相关政策改革进行前瞻性评估。

关键词：全科医疗服务急诊服务世界家庭医生组织利用率 WONCA 论文摘要成年患者汇编

Microglia:a promising therapeutic target in spinal cord injury

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Neural Regeneration Research 2025年第2期20卷 454-463页

作者： Xiaowei Zha Guoli Zheng Thomas Skutella Karl Kiening Andreas Unterberg alexander Younsi Department of Neurosurgery Heidelberg University HospitalHeidelbergGermany Department of Neuroanatomy Institute for Anatomy and Cell BiologyHeidelberg UniversityHeidelbergGermany

Microglia are present throughout the central nervous system and are vital in neural repair,nutrition,phagocytosis,immunological regulation,and maintaining neuronal *** a healthy spinal cord,microglia are accountable for immune surveillance,however,when a spinal cord injury occurs,the microenvironment drastically changes,leading to glial scars and failed axonal *** this context,microglia vary their gene and protein expression during activation,and proliferation in reaction to the injury,influencing injury responses both favorably and unfavorably.A dynamic and multifaceted injury response is mediated by microglia,which interact directly with neurons,astrocytes,oligodendrocytes,and neural stem/progenitor *** a clear understanding of their essential nature and origin,the mechanisms of action and new functions of microglia in spinal cord injury require extensive *** review summarizes current studies on microglial genesis,physiological function,and pathological state,highlights their crucial roles in spinal cord injury,and proposes microglia as a therapeutic target.

关键词： astrocytes cytokines functional recovery immune regulation M1/M2 activation macrophages microglia neuroinflammation spinal cord injury therapy

Treating amyotrophic lateral sclerosis with allogeneic Schwann cell-derived exosomal vesicles: a case report

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Neural Regeneration Research 2025年第4期20卷 1207-1216页

作者： Pascal J.Goldschmidt-Clermont Aisha Khan George Jimsheleishvili Patricia Graham Adriana Brooks Risset Silvera alexander J.P.Goldschmidt Damien D.Pearse W.Dalton Dietrich Allan D.Levi James D.Guest Miller School of Medicine University of MiamiMiamiFLUSA Stem Cell Institute Miller School of MedicineUniversity of MiamiMiamiFLUSA The Miami Project to Cure Paralysis Miller School of MedicineUniversity of MiamiMiamiFLUSA Alzady International LLC MiamiFLUSA Neurological Surgery Miller School of MedicineUniversity of MiamiMiamiFLUSA

Schwann cells are essential for the maintenance and function of motor neurons,axonal networks,and the neuromuscular *** amyotrophic lateral sclerosis,where motor neuron function is progressively lost,Schwann cell function may also be ***,important signaling and potential trophic activities of Schwann cell-derived exosomal vesicles have been *** case report describes the treatment of a patient with advanced amyotrophic lateral sclerosis using serial intravenous infusions of allogeneic Schwann cell-derived exosomal vesicles,marking,to our knowledge,the first instance of such *** 81-year-old male patient presented with a 1.5-year history of rapidly progressive amyotrophic lateral *** initial diagnosis,the patient underwent a combination of generic riluzole,sodium phenylbutyrate for the treatment of amyotrophic lateral sclerosis,and *** patient volunteered to participate in an FDA-approved single-patient expanded access treatment and received weekly intravenous infusions of allogeneic Schwann cell-derived exosomal vesicles to potentially restore impaired Schwann cell and motor neuron *** confirmed that cultured Schwann cells obtained from the amyotrophic lateral sclerosis patient via sural nerve biopsy appeared impaired(senescent)and that exposure of the patient’s Schwann cells to allogeneic Schwann cell-derived exosomal vesicles,cultured expanded from a cadaver donor improved their growth capacity in *** a period of observation lasting 10 weeks,during which amyotrophic lateral sclerosis Functional Rating Scale-Revised and pulmonary function were regularly monitored,the patient received weekly consecutive infusions of 1.54×1012(×2),and then consecutive infusions of 7.5×1012(×6)allogeneic Schwann cell-derived exosomal vesicles diluted in 40 mL of Dulbecco’s phosphate-buffered *** of the infusions were associated with adverse events such as infusion reactions(allergic or otherwise)or

关键词： allogeneic amyotrophic lateral sclerosis exosomes infusion neuromuscular junction Schwann cell

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Gushing metal chain

Frontiers of Mechanical Engineering 2016年第1期11卷 95-100页

作者： alexander BELYAEV alexander SUKHANOV alexander TSVETKOV Institute of Applied Mathematics and Mechanics Saint-Petersburg Polytechnic University St. Petersburg 195251 Russia

This article addresses the problem in which a chain falls from a glass from some height. This phenomenon demonstrates a paradoxical rise of the chain over the glass. To explain this effect, an initial hypothesis and an appropriate theory are proposed for calculating the steady fall parameters of the chain. For this purpose, the modified Cayley ＇s problem of falling chain given its rise due to the centrifugal force of upward inertia is solved. Results show that the lift caused by an increase in linear density at the part of chain where it is being bent （the upper part） is due to the convergence of the chain balls to one another. The experiments confirm the obtained estimates of the lifting chain.

关键词： chain fountain Meshchersky equation,Cayley's problem

Computer study of the formation of water-ammonia clusters and their dielectric properties

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Chinese Physics B 2013年第7期22卷 167-172页

作者： alexander Galashev Institute of Industrial Ecology Ural BranchRussian Academy of Sciences

The absorption of one to six ammonia molecules by the （H2O）50 cluster is studied by the molecular dynamics method under near-atmospheric conditions. The capture of NH 3 molecules by a water cluster produces an increase in the integrated intensity of IR absorbance, substantially decreases emission power in the frequency range of 0≤ω≤3500cm-1,and transforms a continuous reflectance spectrum into a banded one. Adsorption of ammonia molecules by water clusters greatly diminishes the number of electrons that are active with respect to electromagnetic radiation. The present results are also compared with the experimental findings wherever available.

关键词： ammonia water cluster infrared absorption spectra molecular dynamics