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Computational modelling of magnesium degradation in simulated body fluid under physiological conditions

Journal of Magnesium and Alloys 2022年第4期10卷 965-978页

作者： Berit Zeller-Plumhoff Tamadur AlBaraghtheh daniel höche Regine Willumeit-Römer helmholtz-Zentrum hereon Gmbh Institute of Metallic BiomaterialsMax-Planck-Straße 1Geesthacht21502Germany helmholtz-Zentrum hereon Gmbh Institute of Surface ScienceMax-Planck-Straße 1Geesthacht21502Germany

Magnesium alloys are highly attractive for the use as temporary implant materials, due to their high biocompatibility and biodegradability.however, the prediction of the degradation rate of the implants is difficult, therefore, a large number of experiments are required. Computational modelling can aid in enabling the predictability, if sufficiently accurate models can be established. This work presents a generalized model of the degradation of pure magnesium in simulated body fluid over the course of 28 days considering uncertainty aspects. The model includes the computation of the metallic material thinning and is calibrated using the mean degradation depth of several experimental datasets simultaneously. Additionally, the formation and precipitation of relevant degradation products on the sample surface is modelled, based on the ionic composition of simulated body fluid. The computed mean degradation depth is in good agreement with the experimental data(NRMSE=0.07). however, the quality of the depth profile curves of the determined elemental weight percentage of the degradation products differs between elements(such as NRMSE=0.40 for phosphorus vs. NRMSE=1.03 for magnesium). This indicates that the implementation of precipitate formation may need further developments. The sensitivity analysis showed that the model parameters are correlated and which is related to the complexity and the high computational costs of the model. Overall, the model provides a correlating fit to the experimental data of pure Mg samples of different geometries degrading in simulated body fluid with reliable error estimation.

关键词： Biodegradation Magnesium Computational modelling Corrosion Uncertainty quantification Kriging

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A combined computational/experimental study of anode-concerned voltage drop in aqueous primary Mg-air batteries

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Journal of Magnesium and Alloys 2024年第5期12卷 1854-1866页

作者： Wen Xu Min Deng Darya Snihirova Linqian Wang Yulong Wu Sviatlana V.Lamaka Mikhail L.Zheludkevich daniel h?che Institute of Surface Science Helmholtz-Zentrum Hereon School of Materials Science and Engineering Hebei University of Technology Institute for Materials Science Faculty of Engineering Kiel University

The voltage drop appearing at Mg anode-electrolyte interface is a critical issue for the battery power and energy density of aqueous primary Mg-air batteries. The respective voltage loss is typically assigned to the deposits layer forming on the anode surface during discharge. In this work, we experimentally and computationally investigate the critical factors affecting the voltage drop at Mg anode towards a deeper understanding of the contribution of deposit and its growth. A two-dimensional(2D) mathematical model is proposed to compute the voltage drop of Mg-0.15Ca wt.% alloy(Mg-0.15Ca) by means of a semi-empirical formulas and experiments-based modification model, considering the effect of discharge current density, the negative difference effect(NDE) and surface deposits layer itself. This model is utilized to simulate the discharge potential of the anode at predefined experimental current densities. The computed voltage drop(half-cell voltage) is in good agreement with the experimental value. The applicability of the mathematical model is successfully validated on the second material(namely high-purity Mg).

关键词： Aqueous Mg-air battery Voltage drop NDE Charge transfer Deposits-related resistances

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Exploring the contribution of oxygen reduction reaction to Mg corrosion by modeling assisted local analysis

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Journal of Magnesium and Alloys 2023年第1期11卷 100-109页

作者： cheng Wang Wen Xu daniel höche Mikhail L.Zheludkevich Sviatlana V.Lamaka Institute of Surface Science Helmholtz-Zentrum HereonGeesthacht 21502Germany Institute for Materials Science Faculty of EngineeringKiel UniversityKiel 24103Germany

Oxygen reduction reaction(ORR)has been disclosed in recent studies as a significant secondary cathodic process during magnesium corrosion.This work elaborates on the contribution of ORR to the total corrosion process of pure Mg at different impurity levels in NaCl electrolyte with the assistance of local techniques.A finite element based numerical model taking into account the contribution of ORR during the corrosion of the Mg test materials has been designed in this study considering the local oxygen concentration.Respective computational simulations were calibrated based on the experimental data and evaluated accordingly.Finally,the simultaneous monitoring of local concentration of h_(2) and O_(2),and the combined modeling study reveal the relation between ORR and hydrogen evolution reaction.

关键词： Local oxygen concentration Oxygen reduction reaction Mg corrosion NaCl electrolyte hydrogen evolution reaction Numerical model

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Parkland trees on smallholder farms ameliorate soil physical-chemical properties in the semi-arid area of Tigray,Ethiopia

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Journal of Arid Land 2024年第1期16卷 1-13页

作者： Selam LJALEM Emiru BIRhANE Kassa TEKA daniel h BERhE Department of Land Resources Management and Environmental Protection College of Dryland Agriculture and Natural ResourcesMekelle UniversityMekelle 231Ethiopia Institute of Climate and Society Mekelle UniversityMekelle 231Ethiopia Faculty of Environmental Sciences and Natural Resource Management Norwegian University of Life Sciences(NMBU)Ås 1432Norway Department of Natural Resources Management Adigrat UniversityAdigrat 50Ethiopia

Proposed agroforestry options should begin with the species that farmers are most familiar with,which would be the native multipurpose trees that have evolved under smallholder farms and socioeconomic conditions.The African birch(Anogeissus leiocarpa(DC.)Guill.&Perr.)and pink jacaranda(Stereospermum kunthianum Cham.)trees are the dominant species in the agroforestry parkland system in the drylands of Tigray,Ethiopia.Smallholder farmers highly value these trees for their multifunctional uses including timber,firewood,charcoal,medicine,etc.These trees also could improve soil fertility.however,the amount of soil physical and chemical properties enhanced by the two species must be determined to maintain the sustainable conservation of the species in the parklands and to scale up to similar agroecological systems.hence,we selected twelve isolated trees,six from each species that had similar dendrometric characteristics and were growing in similar environmental conditions.We divided the canopy cover of each tree into three radial distances:mid-canopy,canopy edge,and canopy gap(control).At each distance,we took soil samples from three different depths.We collected 216 soil samples(half disturbed and the other half undisturbed)from each canopy position and soil depth.Bulk density(BD),soil moisture content(SMC),soil organic carbon(SOC),total nitrogen(TN),available phosphorus(AP),available potassium(AK),p h,electrical conductivity(EC),and cation exchange capacity(CEC)were analysed.Results revealed that soil physical and chemical properties significantly improved except for soil texture and EC under both species,CEC under A.leiocarpus,and soil p h under S.kunthianum,all the studied soils were improved under both species canopy as compared with canopy gap.SMC,TN,AP,and AK under canopy of these trees were respectively 24.1%,11.1%,55.0%,and 9.3% higher than those soils under control.The two parkland agroforestry species significantly enhanced soil fertility near the canopy of topsoil through improving soil physical and chemica

关键词： agroforestry bulk density carbon stock dispersed tree soil texture tree canopy

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Micro-alloyed Mg-Ca:Corrosion susceptibility to heating history and a plain problem-solving approach

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Journal of Magnesium and Alloys 2023年第4期11卷 1193-1205页

作者： Min Deng Linqian Wang Darya Snihirova Jan Bohlen Gerrit Kurz Sviatlana V.Lamaka daniel höche Mikhail L.Zheludkevich Institute of Surface Science Helmholtz-Zentrum HereonMax-Planck Str.1Geesthacht 21502Germany Institute of Material and Process Design Helmholtz-Zentrum HereonGeesthacht 21502Germany Institute of Materials Science Faculty of EngineeringKiel UniversityKiel 24143Germany

The exceptionally low corrosion rate(∼0.1 mm y^(–1)in concentrated NaCl solution for 7 days)enables lean Mg-Ca alloys great potential for diverse applications,particularly if relevant properties(e.***.mechanical strength,electrochemical performance,etc.)can be enhanced by thermomechanical processing.however,herein it is demonstrated that the corrosion performance of lean Mg-Ca is susceptible to the heating process.The corrosion rate of Mg-0.15 wt%Ca alloy is remarkably accelerated after annealing even for a short time(4 h at 400℃)because Fe precipitation readily takes place.Fortunately,it is found that micro-alloying with dedicated additional elements is able to solve this problem.Nevertheless,the problem-solving capability is dependent on the element category,particularly the ability of the alloying element to constrain the Fe precipitation.Among the three studied elements(i.e.Sn,Ge and In),only In shows good competence of restricting the formation of Fe-containing precipitates,thereby contributing to retention of the superior corrosion resistance after annealing even at a rigorous condition(24 h at 450℃).The finding creates good foundation for follow-up work of developing lean Mg-Ca-based alloys combining high corrosion resistance,superior electrochemical performance with excellent mechanical properties for applications as biodegradable implants and anode materials for aqueous batteries.

关键词： Magnesium Micro-alloying Thermomechanical processing Corrosion Impurity

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World Journal of Otorhinolaryngology-head and Neck Surgery 2024年第2期10卷 97-104页

作者： Mihai A.Bentan Evan R.Reiter Richard M.Costanzo daniel h.Coelho Department of Otolaryngology-head&Neck Surgery Virginia Commonwealth University School of MedicineRichmondVirginiaUSA

Objective:The aim of this study was to review findings from a large prospective national database of chemosensory disturbances associated with coronavirus disease 2019(COVID-19)infection.Data Sources:The Virginia Commonwealth University Smell and Taste Center national database of COVID-19 chemosensory disturbances.Methods:A series of online surveys,first opened on April 10,2020,was made accessible nationwide to any adult with sudden chemosensory dysfunction since January 2020.Participants received subsequent follow-up surveys 14 days,1 month,3 months,and 6 months after enrollment.An additional survey was sent to all participants on May 28,2022 to assess long-term outcomes.Information pertaining to demographics,symptoms,comorbidities,treatments,and life impact was collected.Results:Of 363 participants who reported complete smell recovery,51.2%recovered within 1 month,70%within 3 months,and 79%within 6 months,while 8.8%took over 1 year to completely recover.Among all participants,7.5%had no smell recovery.Positive predictors of recovery included agehe presence of nasal congestion.Negative predictors included difficulty breathing and prior head injury.Many participants reported a decrease in quality of life and the presence of potential safety hazards associated with decreased smell loss.Conclusions:Most subjects with COVID-19-related chemosensory dysfunction recover,with the majority noting complete recovery within weeks of infection.Those aged over 40 years and female gender were associated with lower rates of recovery.A considerable number of participants reported significant impact on quality of life and safety.

关键词： anosmia COVID-19 smell

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Foam rolling and stretching do not provide superior acute flexibility and stiffness improvements compared to any other warm-up intervention: A systematic review with meta-analysis

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Journal of Sport and health Science 2024年第4期13卷 509-520页

作者： Konstantin Warneke Gerit Plöschberger Lars h.Lohmann Eric Lichtenstein daniel Jochum Stanislav D.Siegel Astrid Zech David G.Behm Institute of Sport Science University of KlagenfurtKlagenfurt am Wörthersee 9020Austria Department of human Motion Science and Exercise Physiology Friedrich Schiller UniversityJena 07749Germany Department Sport Exercise and HealthUniversity of BaselBasel 4052Switzerland Department of health Sciences and Technology ETH ZurichZurich 8092Switzerland School of human Kinetics and Recreation Memorial University of NewfoundlandSt.JohnsNL A1C 5S7Canada

Background:Acute improvement in range of motion(ROM)is a widely reported effect of stretching and foam rolling,which is commonly explained by changes in pain threshold and/or musculotendinous stiffness.Interestingly,these effects were also reported in response to various other active and passive interventions that induce responses such as enhanced muscle temperature.Therefore,we hypothesized that acute ROM enhancements could be induced by a wide variety of interventions other than stretching or foam rolling that promote an increase in muscle temperature.Methods:After a systematic search in PubMed,Web of Science,and SPORTDiscus databases,38 studies comparing the effects of stretching and foam rolling with several other interventions on ROM and passive properties were included.These studies had 1134 participants in total,and the data analysis resulted in 140 effect sizes(ESs).ES calculations were performed using robust variance estimation model with R-package.Results:Study quality of the included studies was classified as fair(PEDro score=4.58)with low to moderate certainty of evidence.Results showed no significant differences in ROM(ES=0.01,p=0.88),stiffness(ES=0.09,p=0.67),or passive peak torque(ES=-0.30,p=0.14)between stretching or foam rolling and the other identified activities.Funnel plots revealed no publication bias.Conclusion:Based on current literature,our results challenge the established view on stretching and foam rolling as a recommended component of warm-up programs.The lack of significant difference between interventions suggests there is no need to emphasize stretching or foam rolling to induce acute ROM,passive peak torque increases,or stiffness reductions.

关键词： Range of motion Passive properties Muscletendon unit Muscle tissue

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Comprehensive review of hepatocellular carcinoma with portal vein tumor thrombus:State of art and future perspectives

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hepatobiliary & Pancreatic Diseases International 2024年第3期23卷 221-227页

作者： Paschalis Gavriilidis Timothy M Pawlik daniel Azoulay Department of Surgery Colchester General HospitalTurner RoadColchester CO45JLUK Department of Surgery The Ohio State Wexner Medical CenterJames Comprehensive Cancer CenterColumbusOHUSA Department of hepato-Biliary and Liver Transplantation surgery Paul Brousse University HospitalParis-Saclay UniversityVillejuif 94800France

Background:Despite advances in the diagnosis of patients with hepatocellular carcinoma(hCC),70%-80%of patients are diagnosed with advanced stage disease.Portal vein tumor thrombus(PVTT)is among the most ominous signs of advanced stage disease and has been associated with poor survival if untreated.Data sources:A systematic search of MEDLINE(PubMed),Embase,Cochrane Library and Database for Systematic Reviews(CDSR),Google Scholar,and National Institute for health and Clinical Excellence(NICE)databases until December 2022 was conducted using free text and MeSh terms:hepatocellular carcinoma,portal vein tumor thrombus,portal vein thrombosis,vascular invasion,liver and/or hepatic resection,liver transplantation,and systematic review.Results:Centers of surgical excellence have reported promising results related to the individualized surgical management of portal thrombus versus arterial chemoembolization or systemic chemotherapy.Critical elements to the individualized surgical management of hCC and portal thrombus include precise classification of the portal vein tumor thrombus,accurate identification of the subgroups of patients who may benefit from resection,as well as meticulous surgical technique.This review addressed five specific areas:(a)formation of PVTT;(b)classifications of PVTT;(c)controversies related to clinical guidelines;(d)surgical treatments versus non-surgical approaches;and(e)characterization of surgical techniques correlated with classifications of PVTT.Conclusions:Current evidence from Chinese and Japanese high-volume centers demonstrated that patients with hCC and associated PVTT can be managed with surgical resection with acceptable results.

关键词： hepatectomy Liver surgery Liver neoplasms Portal vein tumor thrombus

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Assessment of scale interactions associated with wake meandering using bispectral analysis methodologies

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Theoretical & Applied Mechanics Letters 2024年第2期14卷 65-75页

作者： Dinesh Kumar Kinjangi daniel Foti Department of Mechanical Engineering University of MemphisMemphisTennesseeUSA

Large atmospheric boundary layer fluctuations and smaller turbine-scale vorticity dynamics are separately hypothesized to initiate the wind turbine wake meandering phenomenon,a coherent,dynamic,turbine-scale oscillation of the far wake.Triadic interactions,the mechanism of energy transfers between scales,manifest as triples of wavenumbers or frequencies and can be characterized through bispectral analyses.The bispectrum,which correlates the two frequencies to their sum,is calculated by two recently developed multi-dimensional modal decomposition methods:scale-specific energy transfer method and bispectral mode decomposition.Large-eddy simulation of a utility-scale wind turbine in an atmospheric boundary layer with a broad range of large length-scales is used to acquire instantaneous velocity snapshots.The bispectrum from both methods identifies prominent upwind and wake meandering interactions that create a broad range of energy scales including the wake meandering scale.The coherent kinetic energy associated with the interactions shows strong correlation between upwind scales and wake meandering.

关键词： Wind turbine wake Mode decomposition Bispectral analysis

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Testing and modelling of transient adhesion phenomena in rolling-sliding contacts

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Friction 2024年第5期12卷 1016-1027页

作者： daniel KVARDA Alexander MEIERhOFER Klaus SIX Faculty of Mechanical Engineering Brno University of TechnologyBrno61669Czech Republic Virtual Vehicle Research Gmbh Graz8010Austria

Transient adhesion effects in rolling–sliding contacts influence all aspects of train–track interaction.This is of high importance specifically when these effects result in critically low adhesion,which poses a risk to traction and braking of railway vehicles.This study presents a model that can replicate the transient changes of the coefficient of adhesion with tested water and solid particle mix.The experimental data for the model are measured using a commercial ball-on-disc tribometer.The experimental results showed a liquid reservoir in front of the contact area that slowly reduces in size.This observation was used in the modelling approach to divide the calculation into two stages where the reservoir is present and when it disappears.The model was able to reproduce the occurrence of low adhesion region seen in experimental results with different particle concentrations.

关键词： coefficient of adhesion tribology transient effects wheel-rail contact

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