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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 ***,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

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Signals in equity‑based crowdfunding and risk of failure

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Financial Innovation 2021年第1期7卷 1199-1228页

作者： felix Reichenbach Martin Walther Chair of Finance and Investment Technische Universität BerlinSec.H 64Straβdes 17.Juni 13510623 BerlinGermany

This study investigates signal validity in equity-based crowdfunding by examining whether signals that increase crowd participation are associated with higher postoffering ***-offering success is measured as the probability of *** use a hand-collected data set of 88 campaigns with over 64,000 investments and 742 updates from a well-established and leading German equity-based crowdfunding platform,*** find that indicating that the chief executive officer holds a university degree and a higher number of business-related updates are associated with a lower risk of failure,which is in line with recent research on offering *** number of updates on external certification,promotions,and the team is associated with a higher risk of *** contrast to recent findings on offering success,we find that the equity share offered is positively related to post-offering success,whereas a high number of large investments or updates on campaign development are accompanied by a higher probability of *** results provide guidance for entrepreneurs and investors regarding which signals are worth sending or ***,these results suggest that investors are partly using wrong signals and challenge the rationality and wisdom of the crowd.

关键词： Equity-based crowdfunding Post-offering success Startup failure Signaling Startups Updates

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Toward a semiotic pyramid:language studies,AI,and knowledge exchange economy

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Language and Semiotic Studies 2023年第3期9卷 393-407页

作者： felix Poschinger Robert Coon University of Hamburg Hamburg 20148 Germany Independent Hamburg Germany

This paper addresses the interrelation between AI and language studies in the(digital)humanities in the context of knowledge exchange *** propose a three-dimensional semiotic model(pyramid)that includes AI as an active agent in meaning-creation into the sign system of communication and test its validity on autocompletion and predictive ***,therefore,analyzed 360 million tweets on COvID-19 over a period of 2 years and focused on the time-dependent shift of language use in the positive and negative extremes correlating to significant external *** data suggest that digital language use has significantly changed over the course of the *** loops are created between Al,utterance,and external reality that fossilize preconceived notions into textual isoglosses by suggesting and completing text *** thus argue that AI subtly changes the perception of reality by influencing the choice of *** mitigate the impact of AI in meaning-creation,we highlight the structural precautions undertaken by providers;we argue,however,that the(digital)humanities may re-emphasize their intrinsic value within the economy of knowledge exchange according to the subject-specific insights they may provide for language use and AI.

关键词： AI digital humanities meaning-creation semiotic pyramid

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Water-Based Processing of Fiberboard of Acrylic Resin Composites Reinforced With Cellulose Wood Pulp and Cellulose Nanofibrils

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Journal of Renewable Materials 2019年第5期7卷 403-413页

作者： Emanoele Maria Santos Chiromito Eliane Trovatti Antonio Jose felix Carvalho Department of Materials Engineering São Carlos School of EngineeringUniversity of São PauloAv.João Dagnone110013563-120São Carlos-SP-Brazil University of Araraquara-UNIARA R.Carlos Gomes1217CEP 14801-320AraraquaraSPBrazil

Despite the great potential of cellulose wood pulp and cellulose nanofibrils as reinforcing filler in thermoplastics,its use is limited due to its tendency to form agglomerates and due to its high hydrophilic *** we describe fiberboard composites with high contents of wood pulp or cellulose nanofibrils,and a resin of poly(styrene-methyl-methacrylate-acrylic acid)used as water-based *** wood pulp and cellulose nanofibrils were used directly in the form of water *** method is based on the flocculation of the polymer emulsion followed by agglomeration of a mixture of the polymer emulsion and cellulose suspension,leading to the co-precipitation of the composite material,which can be easily separated from the water *** with acrylic polymer/cellulose fibers in the proportions of 75:25,50:50 and 25:75 wt%were *** were characterized by scanning electron microscopy(SEM),Fourier transform infrared spectroscopy(FTIR),thermogravimetric analysis(TGA),dynamic mechanical analysis(DMA)and water absorption *** analysis revealed a very good dispersion of the fibers without evidence of agglomeration,which led to superior mechanical *** results showed the effectiveness of the methodology and the potential of cellulose wood pulp and CNF as reinforcement fillers in fiberboard composites and any other high fiber-content materials.

关键词： Cellulose wood pulp cellulose nanofibrils composites acrylic resin emulsion fiberboard

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Thermal and Mechanical Properties of Thermoplastic Starch and Poly(Vinyl Alcohol-Co-Ethylene)Blends

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Journal of Renewable Materials 2019年第3期7卷 245-252页

作者： Ana Clara Lancarovici Alves Rafael Grande Antonio José felix Carvalho Department of Materials Engineering Sao Carlos School of EngineeringUniversity of Sao PauloAv.Joao Dagnone110013563-120Sao Carlos-SP-Brazil

The interest in thermoplastic starch(TPS)as a substitute material to replace conventional thermoplastics continues especially due its biodegradability,availability,low cost and because it is obtained from renewable ***,its poor mechanical properties and its high sensitivity to humidity have limited its use in several ***,the copolymer poly(ethylene-co-vinyl alcohol)(EVOH),with two different ethylene contents,27 and 44 mol%were blended with TPS by extrusion in order to overcome these *** obtained blends were characterized by thermogravimetric analysis(TGA),differential scanning calorimetry(DSC),mechanical tensile testing,Scanning Electron Microscopy(SEM)and moisture absorption *** addition of EVOH copolymer did not significantly changed the thermal stability of TPS,however it increased the tensile strength in 65%when compared to *** morphology of the blends did not showed two distinct phases,an indication of miscibility or partial miscibility of the components.A decrease of moisture absorption was obtained by the addition of EVOH and is more pronounced for the EVOH with 44% of ethylene.

关键词： Thermoplastic starch EVOH polymer blends thermal properties of polymers mechanical properties of polymers

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Nitrogen-doped Porous Carbon Derived from Surface-attached Polymer Layers for Oxygen Reduction Reaction under Acidic Conditions

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Journal of Wuhan University of Technology(Materials Science) 2017年第6期32卷 1287-1292页

作者：潘向川 BOAKYE felix Ofori LIU Kai 张海宁 State Key Laboratory of Advanced Technology for Materials Synthesis and Processing Wuhan University of Technology Wuhan 430070 China

We reported the synthesis of nitrogen-doped carbon using surface-attached polyelectrolyte layers as precursors. The synthesized material has a large surface area of 800 m^2·g^-1 with uniformed pore distribution. Benefitfed from the high pyridinic nitrogen content, the synthesized nitrogen-doped porous carbon material exhibits promising electrocatalytic activity toward oxygen reduction reactions in acidic medium and very high stability against continuous cyclic voltammetry scans. The experimental results demonstrate that surface-attached polyelectrolyte layers are promising carbon and nitrogen sources for the formation of heteroatom-doped porous carbon materials.

关键词： mesoporous materials polyelectrolyte carbon surface-attachment oxygen reduction stability

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Nitrogen nutrition,carbon accumulation andδ^(13)C of Cyclopia and Aspalathus species in different settings of the Cape fynbos,South Africa

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Journal of Plant Ecology 2016年第5期9卷 586-595页

作者： Sipho T.Maseko felix D.Dakora Department of Crop Sciences Tshwane University of TechnologyPrivate Bag X680Pretoria 0001South Africa Chemistry Department Tshwane University of TechnologyPrivate Bag X680Pretoria 0001South Africa

Aims Cyclopia and Aspalathus are legumes harvested for production of Honeybush and Rooibos tea,*** grow these species from either seeds or cuttings over several years with continuous annual *** aims of this study were to assess the effect of plant age,plant species,toposequence,planting material and farmer practice on nitrogen(N)nutrition and water-use efficiency of two Cyclopia and Aspalathus species in the Cape *** The study was conducted using plants from Koksrivier farm located near Gansbaai(33°S 18°E,39 m.a.s.l),and at Kanetberg farm near Barrydale(33°S 21°E,830 m.a.s.l).The 15N natural abundance technique was used to determine N_(2)fixation,carbon(C)assimilation andδ^(13)C in shoot of Cyclopia and Aspalathus *** Findings Older tea plantations of *** and *** derived more N from fixation and exhibited greater water-use efficiency than younger *** Koksrivier,Aspalathus caledonensis and *** showed greater water-use efficiency and derived more N from fixation than Cyclopia *** harvesting of *** decreased N_(2)*** Kanetberg,***-nata plants on the upper and middle slopes derived more N from atmospheric fixation than those on the lower *** plants grown from seedlings recorded greater%Ndfa than cuttings.N_(2)fixation and water-use efficiency of Cyclopia was affected by age,slope and planting ***,symbiotic N nutrition and water-use efficiency of Cyclopia and Aspalathus were related.

关键词： Cyclopia subternata Cyclopia genistoides Koksrivier Kanetberg fynbos

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Relationship between acid phosphatase activity and P concentration in organs of Cyclopia and Aspalathus species,and a non-legume of the Cape Floristic Region

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Journal of Plant Ecology 2019年第2期12卷 387-392页

Aims The role of tissue acid phosphatase(APase)activity of legumes and non-legumes in their P nutrition and adaptation to low-P soils is not well *** better understand this,a relationship between APase activ-ity and P concentration in leaves,stems,roots and nodules of legumes,Cyclopia and Aspalathus and a non-legume,Leucadendron strictum,all native to the P-poor soils of the Cape fynbos biome,was *** Plants were collected and each separated into leaves,stems and *** enzyme activity was assayed in soil using the p-nitrophenol method,while soil P and shoot P were measured using *** measure tissue APase activity,an acetate buffer was added into ground plant material and contents *** ace-tate buffer and a p-nitrophenyl solution were added to the superna-tant and contents *** incubation,NaOH(0.5 M)was added and absorbance read at 405 *** Findings At Koksrivier,Cyclopia genistoides exhibited the highest leaf enzyme activity whilst Aspalathus aspalathoides showed the highest enzyme activity in the *** both Kleinberg and Kanetberg,Cyclopia subternata and Cyclopia longifolia showed the highest APase activity in leaves,followed by stems and low-est in roots.P concentration closely mirrored enzyme activity in organs of all test species from each *** activity posi-tively correlated with P concentration in organs of all the test Cyclopia and Leucadendron species,indicating that intracellular APase activity is directly linked to P mobilization and transloca-tion in these *** of N derived from fixation was positively correlated with tissue APase activity in ***(r=0.911^(*)),***(r=0.868^(*))and Aspalathus cal-edonensis(r=0.957^(*)),suggesting that APase activity could be directly or indirectly linked to symbiotic functioning in these fynbos legumes,possibly via increased P supply to sites of N2 fixation.

关键词： Cape fynbos δ^(15)N Leucadendron strictum percent N derived from fixation P nutrition

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Changes in demand and supply of ecosystem services under scenarios of future land use in Vorarlberg, Austria

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Journal of Mountain Science 2019年第12期16卷 2793-2809页

作者： SAUTER Isabel KIENAST felix BOLLIGER Janine WINTER Benjamin PAZuR Robert Swiss Federal Research Institute WSL Zurcherstrasse 1118903 BirmensdorfSwitzerland ALPS-Centre for Climate Change Adaptation Grabenweg 686020 InnsbruckAustria Institute of Geography University of InnsbruckInnrain 526020 InnsbruckAustria Institute of Geography Slovak Academy of SciencesStefanikova 4981473 BratislavaSlovakia

Ecosystem services(ES)are highly impacted by human-induced land-use *** urbanization and agricultural land abandonment in Western Europe necessitate assessments of future land-change impacts on ES to ensure sustainable service *** present study aims at evaluating future demand and supply of three key services(flood protection,nearby recreation and biodiversity)in the mountainous region of Vorarlberg,*** mapped the ES for the referenced time step 2016 and two scenarios for 2050,assuming the continuation of current land-change trends and pressure on landscape *** for the referenced landscape in 2016 show the highest ES supply for intermediate levels,while ES supply was low in the lowlands and valley bottoms and in high-elevation *** found a high positive correlation of ES with the distribution of forested *** contrast,service demand was highest in lowelevation areas and decreased with increasing *** indicates that densely settled and intensively used agricultural areas currently suffer from ES *** projected future development of land use showed an increase in both supply and demand of the selected *** overall service supply increased more than the respective demand due to some reforestation of open *** forests were found to be important synergistic areas for overall service provision,we expect decreasing demand on related ***,demand was found to exceed the supply of ES,especially in the densely populated Rhine valley-requiring further policy *** ES-related information may contribute to regional policy making and ensure the long-term provision of ESs for future generations.

关键词： Land-use change Future land-use scenarios Regional assessment Ecosystem services Synergies Conflicts

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Symbiotic performance,shoot biomass and water-use efficiency of three groundnut(Arachis hypogaea L.)genotypes in response to phosphorus supply under field conditions in Ethiopia

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Frontiers of Agricultural Science and Engineering 2020年第4期7卷 455-466页

作者： Sofiya KMUHABA felix DDAKORA Department of Soil Fertility and Health Management Debre Zeit Agricultural Research CenterEthiopian Institute of Agricultural ResearchPO Box 32Debre ZeitEthiopia Department of Crop Sciences Tshwane University of TechnologyPrivate Bag X680Pretoria 0001South Africa Department of Chemistry Tshwane University of TechnologyArcadia CampusPrivate Bag X680175 Nelson Mandela DrivePretoria 0001South Africa

Phosphorus is a key nutrient element involved in energy transfer for cellular metabolism,respiration and photosynthesis and its supply at low levels can affect legume nodulation,N2 fixation,and C assimilation.A twoyear field study was conducted in Ethiopia in 2012 and 2013 to evaluate the effects of P supply on growth,symbiotic N2 nutrition,grain yield and water-use efficiency of three groundnut *** P to the genotypes significantly increased their shoot biomass,symbiotic performance,grain yield,and C *** was,however,no effect on shootδ13C values in either *** to the zero-P control,supplying 40 kg$ha–1 P markedly increased shoot biomass by 77%and 66%in 2012 and 2013,*** both years,groundnut grain yields were much higher at 20 and 30 kg$ha–1 *** supply markedly reduced shootδ15N values and increased the%Ndfa and amount of Nfixed,indicating the direct involvement of P in promoting N2 fixation in nodulated *** three genotypes differed significantly inδ15N,%Ndfa,N-fixed,grain yield,C concentration,andδ*** phosphorusgenotype interaction was also significant for shoot DM,N content,N-fixed and soil N uptake.

关键词： shoot yield N-fixed %Ndfa δ15N δ13C water-use efficiency

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