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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 corrosion.This framework uses a python-based algorithm to analyse microcomputer-tomography scans(μCT)of cylindrical specimens undergoing corrosion.The 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 G46-94.Furthermore,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 established.Results demonstrated that several of the parameters described in ASTM G46-94,including pit number,pit density and pitting factor,showed little correlation to mechanical performance.However,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 specimen.Specifically,our results indicate,that parameters directly linked to the loss of the cross-sectional area(e.***.minimum material width),are parameters that are most suited to provide an indication of a specimen’s mechanical performance.The 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

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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 process.First,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 testing.Then the experimental data of both unmodified and PEO-modified groups were used to calibrate parameters of a finite element-based surface corrosion model.In-vitro,it was found that the WE43-PEO modified group had a significantly lower corrosion rate and maintained significantly higher mechanical properties than the unmodified.While 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 time.We 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 corrosion.Using the results from the testing framework,the model parameters of the surface-based corrosion model were identified for both groups.This 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 specimens.This 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

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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 failure.The python-based detection framework PitScan provides detailed quantification of the spatial phenomenological features of corrosion,including a full geometric tracking of corroding surface.Through 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 data.Using 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 features.In 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 corrosion.Interestingly,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 Pitscan.This 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

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Neuronal trafficking as a key to functional recovery in immune-mediated neuropathies

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Neural Regeneration Research 2024年第11期19卷 2331-2332页

作者： felix Kohle Michael Schroeter Department of Neurology University of Cologne and University Hospital CologneCologneGermany

Immune-mediated neuropathies are rare diseases of the peripheral nervous system(PNS),substantially affecting patients’functionality and quality of life.They are amenable to immunomodulatory treatments,which in many cases stabilize disease progression,but long-term deficits persist in many patients.Such long-term deficits are particularly observed in monophasic autoimmune neuropathies like Guillain-Barrésyndrome and also in chronic variants,e.g.,chronic inflammatory demyelinating neuropathy(Fadia et al.,2019).

关键词： diseases autoimmune

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Cognitive dissonance and mindset perturbations during crisis:“ecosocio-psycho-somatic”perspectives

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World Journal of Psychiatry 2024年第2期14卷 215-224页

作者： felix Tretter Henriette Löffler-Stastka Department of Systems Medicine and Healthcare Systems Bertalanffy Center for the Study of Systems ScienceVienna 1040Austria Department of Psychoanalysis and Psychotherapy Medical University ViennaVienna 1090Austria

Mandatory and restrictive health regulations during the corona pandemic caused psychic disorders in many people,which even led to clinically relevant mental disorders.At the same time,there was gradually a polarization of opinions among the population.In order to improve future pandemic management,an integrative understanding of these psychosocial processes therefore seems useful.Here we start theoretically with the mental effects of inconsistencies of the information environment by referring to concepts such as the theory of cognitive dissonance.In a next step,we use the psychodynamic theory to understand the affective-motivational defense mechanisms underlying these cognitive states and processes.However,a broader theoretical framework of psychoanalysis seems to make sense,because self-referential processing also influences the style of thinking.For this reason,we use a more comprehensive psychological systems theoretical framework model to integrate these different perspectives.This integrative view refers in part to basic knowledge of health psychology regarding the resistance of unhealthy ways of thinking and behaviors and the possibilities for interventions for change.We then extend this model to a broader picture that also covers the relationship between men and their environment.This results in the perspective of a multidimensional socioecological theoretical framework,which as a heuristic reference model and related to other ecological approaches could also be helpful for various theoretical questions for public health,and could provide a better public understanding of health issues.In line with this perspective,we hypothesize that with regard to the coronavirus disease 2019 pandemic,the acceptance of public health narratives could be increased if a more consistent picture of the scientific descriptions and explanations of the pandemic-similar to the model proposed-could be provided,which would enable the understanding of the origin,course and countermeasures,and thus could have positive collective psych

关键词： Infodemic Affective-cognitive dissonance Systems model of the mind Socioecological model

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Exploring the size of Andean condor foraging groups along an altitudinal and latitudinal gradient in the Tropical Andes: Ecological and conservation implications

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Current Zoology 2024年第2期70卷 225-232页

作者： Diego Mendez felix Hernan Vargas JoséHernan Sarasola Pedro P.Oleaa Departamento de Ecologia Universidad Autonoma de MadridCalle Darwin 228049MadridSpain Museo Nacional de Historia Natural Calle 26 s/nCota CotaLa PazBolivia The Peregrine Fund 5668 West Flying Hawk LaneBoiseID 83709USA Centro para el Estudio y Conservacion de Aves Rapaces en Argentina(CECARA) Universidad Nacional de La PampaAvda Uruguay 1516300 Santa RosaLa PampaArgentina Instituto de las Ciencias Ambientales y de la Tierra de La Pampa(INCITAP-CONICET) Avda.Uruguay 1516300 Santa RosaLa PampaArgentina Centro de Investigacion en Biodiversidad y Cambio Global(CIBC-UAM) Universidad Autonoma de MadridMadridCalle Darwin 228049Madrid Snain

Patterns of variation in the size of vulture foraging groups,and their ecological causes and consequences,remain litle explored despite strong links with the carrion recycling service that this key functional group provides.We documented the group size-frequency pattern of Andean con-dors Vultur gryphus gathered to feed on 42 equine carcasses experimentally placed in Bolivia,between 2012 and 2019,along an elevation range of 1,300-4,500 m asl.Based on the location(altitude and latitude)of the foraging groups,we examined the relationship between their size and species'population parameters(size and trend),habitat conditions,and livestock carcass availability and predictability.Condors utilized a high frequency(93%)of carcasses forming groups that ranged from 1 to 80 individuals(mean=25,median=18)and shaped a"lazy-J curve"typical pattern of size-frequency distribution whereby few groups(5,12%)were large(>55 individuals)and most(21,50%)were relatively small(<19 individuals).Group size related to altitude in that most larger groups formed at lower sites(below c.3,000 m asl),likely following an altitudinal gradient whereby larger groups are more likely to form around larger carcasses(i.e.,cattle),which are more likely to occur at lower elevations.Regardless of population size,group size could be an adaptive response of condors via local enhancement for improving individual scavenging efficiency.Many information gaps on this topic still exist,thus we provide a set of questions to address them,especially amidst the unrestricted impacts of human activities that condition vulture survival globally.

关键词： condor andino fusion-fission dynamics group size scavenger social foraging vultures.

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A CFD Model to Evaluate Near-Surface Oil Spill from a Broken Loading Pipe in Shallow Coastal Waters

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Fluid Dynamics & Materials Processing 2024年第1期20卷 59-77页

作者： Portia felix Lee Leon Derek Gay Stefano Salon Hazi Azamathulla Department of Civil and Environmental Engineering The University of the West IndiesSt.AugustineTrinidad and Tobago National Institute of Oceanography and Experimental Geophysics-OGS TriesteItaly

Oil spills continue to generate various issues and concerns regarding their effect and behavior in the marine environment,owing to the related potential for detrimental environmental,economic and social implications.It is essential to have a solid understanding of the ways in which oil interacts with the water and the coastal ecosystems that are located nearby.This study proposes a simplified model for predicting the plume-like transport behavior of heavy Bunker C fuel oil discharging downward from an acutely-angled broken pipeline located on the water surface.The results show that the spill overall profile is articulated in three major flow areas.The first,is the source field,i.e.,a region near the origin of the initial jet,followed by the intermediate or transport field,namely,the region where the jet oil flow transitions into an underwater oil plume flow and starts to move horizontally,and finally,the far-field,where the oil re-surface and spreads onto the shore at a significant distance from the spill site.The behavior of the oil in the intermediate field is investigated using a simplified injection-type oil spill model capable of mimicking the undersea trapping and lateral migration of an oil plume originating from a negatively buoyant jet spill.A rectangular domain with proper boundary conditions is used to implement the model.The Projection approach is used to discretize a modified version of the Navier-Stokes equations in two dimensions.A benchmark fluid flow issue is used to verify the model and the results indicate a reasonable relationship between specific gravity and depth as well as agreement with the aerial data and a vertical temperature profile plot.

关键词： CFD model Navier-Stokes equations projection method water surface oil spill shallow coastal waters

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Amyloid-β-induced disruption of axon-initial-segment mitochondria localization:consequences for TAU missorting in Alzheimer's disease pathology

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Neural Regeneration Research 2025年第5期20卷 1407-1408页

作者： Daniel Adam felix Langerscheidt Hans Zempel Institute of Human Genetics University Hospital CologneCologneGermany Center for Molecular Medicine Cologne(CMMC) University of CologneCologneGermany

TAU is a neuronal microtubule-associated protein preferentially located in axons.In a battery of neurodegenerative diseases termed"tauopathies,"including Alzheimer's disease (AD),TAU is missorted and abnormally phosphorylated,leading to filamentous accumulations of hyperphosphorylated TAU,a pathological hallmark and potential disease driver of AD and related tauopathies (Zempel,2024).

关键词： Alzheimer tau diseases

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Prediction of Porous Media Fluid Flow with Spatial Heterogeneity Using Criss-Cross Physics-Informed Convolutional Neural Networks

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Computer Modeling in Engineering & Sciences 2024年第2期138卷 1323-1340页

作者： Jiangxia Han Liang Xue Ying Jia Mpoki Sam Mwasamwasa felix Nanguka Charles Sangweni Hailong Liu Qian Li State Key Laboratory of Petroleum Resources and Prospecting China University of PetroleumBeijing102249China Department of Oil-Gas Field Development Engineering College of Petroleum EngineeringChina University of PetroleumBeijing102249China Exploration Production Research Institute SinopecBeijing102249China Ministry of Energy Tanzania Petroleum Development CorporationTowerDar es Salaam2774Tanzania Ministry of Energy Building Petroleum Upstream Regulatory Authority in Tanzania(PURA)Dar es Salaam11439Tanzania

Recent advances in deep neural networks have shed new light on physics,engineering,and scientific computing.Reconciling the data-centered viewpoint with physical simulation is one of the research hotspots.The physicsinformedneural network(PINN)is currently the most general framework,which is more popular due to theconvenience of constructing NNs and excellent generalization ability.The automatic differentiation(AD)-basedPINN model is suitable for the homogeneous scientific problem;however,it is unclear how AD can enforce fluxcontinuity across boundaries between cells of different properties where spatial heterogeneity is represented bygrid cells with different physical properties.In this work,we propose a criss-cross physics-informed convolutionalneural network(CC-PINN)learning architecture,aiming to learn the solution of parametric PDEs with spatialheterogeneity of physical properties.To achieve the seamless enforcement of flux continuity and integration ofphysicalmeaning into CNN,a predefined 2D convolutional layer is proposed to accurately express transmissibilitybetween adjacent cells.The efficacy of the proposedmethodwas evaluated through predictions of several petroleumreservoir problems with spatial heterogeneity and compared against state-of-the-art(PINN)through numericalanalysis as a benchmark,which demonstrated the superiority of the proposed method over the PINN.

关键词： Physical-informed neural networks(PINN) flow in porous media convolutional neural networks spatial heterogeneity machine learning

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Factors Affecting Cotrimoxazole Prophylactic Therapy Compliance in HIV Patients Attending a Care and Treatment Clinic at Bugando Medical Centre in Mwanza, Tanzania

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Advances in Infectious Diseases 2024年第2期14卷 456-468页

作者： Stanley Mwita felix Tarimo Rahma Mbalamla Department of Pharmaceutics and Pharmacy Practice Catholic University of Health and Allied Sciences Mwanza Tanzania Department of Biochemistry Catholic University of Health and Allied Sciences Mwanza Tanzania

Introduction: Cotrimoxazole Prophylactic Therapy (CPT) compliance lowers the risk of opportunistic infections and other Acquired Immune Deficiency Syndrome (AIDS)-related diseases. The aim of this study was to examine factors that influence compliance with CPT among HIV patients in the Care and Treatment Clinic (CTC) at Bugando Medical Centre (BMC) in Mwanza, Tanzania. Methods: A descriptive cross-sectional study was conducted at the BMC between April 1, 2021, and June 30, 2021. Data were collected using face-to-face interviews and a semi-structured questionnaire. Data are presented in frequency, percentages, and cross-tabulation tables. A P-value of less than 0.05 was considered statistically significant. Results: The prevalence of compliance with CPT by self-reported measurement was 158 (63.7%). Most CPT-compliant participants were more likely to have a spouse who is familiar with CPT, have a family member who is aware of their HIV status, and be aware of the benefits of CPT. The majority of participants who complied with CPT were more likely to have experienced counseling during refill, felt that the length of time spent seeing doctors for treatment was reasonable, and received accurate information from them. Conclusion: Most adult HIV patients attending CTC at BMC were reported to be in compliance with CPT. These findings suggest that improving social support and patient-provider communication may be effective strategies for improving compliance with CPT among HIV patients.

关键词： Factors Compliance Co-Trimoxazole Prophylactic Therapy HIV/AIDS Tanzania Bugando Medical Centre

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