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Pore characterization of PM Mg–0.6Ca alloy and its degradation behavior under physiological conditions

Journal of Magnesium and Alloys 2021年第2期9卷 686-703页

作者： Eshwara Phani Shubhakar Nidadavolu diana krüger Berit Zeller-Plumhoff Domonkos Tolnai Björn Wiese Frank Feyerabend Thomas Ebel Regine Willumeit-Römer Division Metallic Biomaterials Institute of Materials ResearchHelmholtz-Zentrum GeesthachtMax-Planck-Str.1Geesthacht 21502Germany Magnesium Innovation Center(MagIC) Institute of Materials ResearchHelmholtz-Zentrum GeesthachtMax-Planck-Str.1Geesthacht 21502Germany

Several material parameters affect degradation characteristics of Mg and its alloys under physiological *** Mg materials are interesting for their simultaneous degradation and drug delivery ***,an increase in pore surface area is detrimental to both degradation resistance and subsequent mechanical *** present work aims at determining the threshold porosity value in Mg–0.6 Ca specimens produced by powder metallurgy(PM)below which low degradation rates persist with acceptable mechanical *** different porous Mg–0.6 Ca specimens containing both closed and open pore structures were fabricated with porosities ranging from 3%to 21%.Degradation profiles were obtained via a semi static immersion test over 16 days under physiological conditions using Dulbecco’s modified Eagle’s medium with Glutamax and 10%fetal bovine serum as *** results are related to morphological pore parameters like pore size distribution,pore interconnectivity and pore curvatures that were quantified using an ex situμCT *** general,with decreasing porosity a decrease in pore interconnectivity is seen followed by rounding of the *** degradation rates(MDR<0.3 mm/year)are observed in specimens until 10%porosity,however,the upper bound for reproducible degradation is observed to be in specimens until 12%*** porosity level also marks the transition from closed to open pore nature with a simultaneous change in pore interconnectivity from less than 10%to greater than 95%,below and above this porosity level,*** tensile strength and elongation to failure recorded for specimens with 10%porosity were 70 MPa and 2%,respectively displaying positive traits of both homogenous degradation and mechanical *** results suggest that high pore interconnectivity is the dominant factor controlling degradation and mechanical properties in porous Mg-0.6 Ca *** results also indicate a good sintering respons

关键词： Porous Mg-0.6Ca In vitro Degradation μCT Sintering

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Assessing the microstructure and in vitro degradation behavior of Mg-xGd screw implants using μCT

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Journal of Magnesium and Alloys 2021年第6期9卷 2208-2223页

作者： diana krüger Berit Zeller-Plumhoff Björn Wiese Sangbong Yi Marcus Zuber D.C.Florian Wieland Julian Moosmann Regine Willumeit-Römer Institute of Metallic Biomaterials Helmholtz-Zentrum HereonMax-Planck-Str.1Geesthacht 21502Germany Institute of Material and Process Design Helmholtz-Zentrum HereonMax-Planck-Str.1Geesthacht 21502Germany Institute for Photon Science and Synchrotron Radiation Karlsruhe Institute of TechnologyHerrmann-von-Helmholtz-Platz 1Eggenstein-Leopoldshafen 76344Germany Laboratory for Applications of Synchrotron Radiation Karlsruhe Institute of TechnologyKaiserstr.12KarlsruheGermany Institute of Materials Physics Helmholtz-Zentrum HereonMax-Planck-Str.1Geesthacht 21502Germany

Biodegradable implants are taking an increasingly important role in the area of orthopedic implants with the aim to replace permanent implants for temporary bone healing *** the implant preparation process,the material’s surface and microstructure are being changed by stresses induced by *** degradable metal implants need to be fully characterized in terms of the influence of machining on the resulting microstructure and corrosion *** this study,micro-computed tomography(μCT)is used for the quantification of the degradation rate of biodegradable *** our best knowledge,for the first time quantitative measures are introduced to describe the degradation homogeneity in *** information enables a prediction in terms of implant stability during the degradation in the *** magnesium gadolinium alloys,Mg-5Gd and Mg-10 Gd(all alloy compositions are given in weight%unless otherwise stated),in the shape of M2 headless screws have been investigated for their microstructure and their degradation performance up to 56 *** the microstructure investigations particular attention was paid to the localized deformation of the alloys,due to the machining *** vitro immersion testing was performed to assess the degradation performance quantified by subsequent weight loss and volume loss(usingμCT)*** differences were observed in the degree of screw’s near surface microstructure being influenced from machining,the degradation rates of both materials appeared to be suitable for application in orthopedic *** the degradation homogeneity point of view no obvious contrast was detected between both ***,the higher degradation depth ratios between the crests and roots of Mg-5Gd ratios may indicated a less homogeneous degradation of the screws of these alloys on contract to the ones made of Mg-10Gd *** to its lower degradation rates,its more homogeneous microstructure,its weaker texture

关键词： Magnesium alloys Biodegradable implant Degradation rate Degradation homogeneity Micro-comptued tomography

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On the material dependency of peri-implant morphology and stability in healing bone

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Bioactive Materials 2023年第10期28卷 155-166页

作者： Stefan Bruns diana krüger Silvia Galli D.C.Florian Wieland Jorg U.Hammel Felix Beckmann Ann Wennerberg Regine Willumeit-Romer Berit Zeller-Plumhoff Julian Moosmann Institute of Metallic Biomaterials Helmholtz-Zentrum HereonMax-Planck-Str.121502GeesthachtGermany University of Malmo Faculty of OdontologyDepartment of ProsthodonticsCarl Gustafs Vag 34Klerken20506MalmoSweden Institute of Materials Physics Helmholtz-Zentrum HereonMax-Planck-Str.121502GeesthachtGermany University of Gothenburg Institute of OdontologyDepartment of ProsthodonticsMedicinaregatan 12 f41390GoteborgSweden

The microstructural architecture of remodeled bone in the peri-implant region of screw implants plays a vital role in the distribution of strain energy and implant *** present a study in which screw implants made from titanium,polyetheretherketone and biodegradable magnesium-gadolinium alloys were implanted into rat tibia and subjected to a push-out test four,eight and twelve weeks after *** were 4 mm in length and with an M2 *** loading experiment was accompanied by simultaneous three-dimensional imaging using synchrotron-radiation microcomputed tomography at 5μm *** deformation and strains were tracked by applying optical flow-based digital volume correlation to the recorded image *** stabilities measured for screws of biodegradable alloys were comparable to pins whereas non-degradable biomaterials experienced additional mechanical ***-implant bone morphology and strain transfer from the loaded implant site depended heavily on the biomaterial *** implants stimulated rapid callus formation displaying a consistent monomodal strain profile whereas the bone volume fraction in the vicinity of magnesium-gadolinium alloys exhibited a minimum close to the interface of the implant and less ordered strain *** in our data suggest that implant stability benefits from disparate bone morphological properties depending on the biomaterial *** leaves the choice of biomaterial as situational depending on local tissue properties.

关键词： Biodegradable implant materials Bone mechanical testing Implant stability Synchrotron micro-computed tomography imaging Digital volume correlation

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High-resolution ex vivo analysis of the degradation and osseointegration of Mg-xGd implant screws in 3D

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Bioactive Materials 2022年第7期7卷 37-52页

作者： diana krüger Silvia Galli Berit Zeller-Plumhoff D.C.Florian Wieland Niccolo Peruzzi Bjorn Wiese Philipp Heuser Julian Moosmann Ann Wennerberg Regine Willumeit-Romer Institute of Metallic Biomaterials Helmholtz-Zentrum HereonMax-Planck-Str.1Geesthacht21502Germany University of Malmo Faculty of OdontologyDepartment of ProsthodonticsCarl Gustafs vag 34Klerken20506MalmoSweden Lund University Department of Clinical Sciences LundMedical Radiation PhysicsBarngatan 422242LundSweden Deutsches Elektronen-Synchrotron(DESY) Notkestrasse 8522607HamburgGermany Institute of Materials Physics Helmholtz-Zentrum HereonMax-Planck-Str.1Geesthacht21502Germany University of Gothenburg Institute of OdontologyDepartment of ProsthodonticsMedicinaregatan 12 f41390GoteborgSweden

Biodegradable magnesium(Mg)alloys can revolutionize osteosynthesis,because they have mechanical properties similar to those of the bone,and degrade over time,avoiding the need of removal ***,they are not yet routinely applied because their degradation behavior is not fully *** this study we have investigated and quantified the degradation and osseointegration behavior of two biodegradable Mg alloys based on gadolinium(Gd)at high ***-5Gd and Mg-10Gd screws were inserted in rat tibia for 4,8 and 12 ***,the degradation rate and degradation homogeneity,as well as bone-to-implant interface,were studied with synchrotron radiation micro computed tomography and ***(Ti)and polyether ether ketone(PEEK)were used as controls material to evaluate *** results showed that Mg-5Gd degraded faster and less homogeneously than *** alloys gradually form a stable degradation layer at the interface and were surrounded by new bone *** results were correlated to in vitro data obtained from the same material and *** average bone-to-implant contact of the Mg-xGd implants was comparable to that of Ti and higher than for *** results suggest that both Mg-xGd alloys are suitable as materials for bone implants.

关键词： Magnesium alloys Biodegradable implant Micro-computed tomography degradation rate Degradation homogeneity Ex vivo imaging Ex vivo histology Histology vs.tomography

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MARIE:One-Stage Object Detection Mechanism for Real-Time Identifying of Firearms

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Computer Modeling in Engineering & Sciences 2025年第1期142卷 279-298页

作者： diana Abi-Nader Hassan Harb Ali Jaber Ali Mansour Christophe Osswald Nour Mostafa Chamseddine Zaki Computer Science Department Faculty of SciencesLebanese UniversityBeirut146404Lebanon College of Engineering and Technology American University of the Middle EastEgaila54200Kuwait Lab-STICC CNRS UMR 6285ENSTA-BretagneBrest29200France

Security and safety remain paramount concerns for both governments and individuals *** today’s context,the frequency of crimes and terrorist attacks is alarmingly increasing,becoming increasingly intolerable to ***,there is a pressing need for swift identification of potential threats to preemptively alert law enforcement and security forces,thereby preventing potential attacks or violent *** advancements in big data analytics and deep learning have significantly enhanced the capabilities of computer vision in object detection,particularly in identifying *** paper introduces a novel automatic firearm detection surveillance system,utilizing a one-stage detection approach named MARIE(Mechanism for Realtime Identification of Firearms).MARIE incorporates the Single Shot Multibox Detector(SSD)model,which has been specifically optimized to balance the speed-accuracy trade-off critical in firearm detection *** SSD model was further refined by integrating MobileNetV2 and InceptionV2 architectures for superior feature extraction *** experimental results demonstrate that this modified SSD configuration provides highly satisfactory performance,surpassing existing methods trained on the same dataset in terms of the critical speedaccuracy *** these innovations,MARIE sets a new standard in surveillance technology,offering a robust solution to enhance public safety effectively.

关键词： Firearm and gun detection single shot multi-box detector deep learning one-stage detector MobileNet inception convolutional neural network

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Automatic route planning for GPS art generation

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Computational Visual Media 2019年第3期5卷 303-310页

作者： Andre Waschk Jens krüger University of Duisburg-Essen

In this paper, we present a novel approach to automated route generation of global positioning system(GPS) artwork. The term GPS artwork describes the generation of drawings by leaving virtual traces on digital maps. Until now, the creation of these images has required a manual planning phase in which an artist designs the route by hand. Once the route for this artwork has been planned, GPS devices have been used to track the movement. Using our solution, the lengthy planning phase can be significantly shortened,thereby opening art creation to a broader public.

关键词： GPS art walking routing shape detection navigation

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IRFs as competing pioneers in T-cell differentiation

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Cellular & Molecular Immunology 2017年第8期14卷 649-651页

作者： Andrea kröger Institute for Medical Microbiology Molecular MicrobiologyOtto-von-Guericke University of MagdeburgMagdeburg D-39120Germany

CD4-expressing T lymphocytes are among of the best-characterized immune system cells.1 They develop in the thymus and acquire the potential to differentiate into distinct *** leaving the thymus,T helper cells further ... 详细信息

关键词： lymphocytes expressing pioneer

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Add on the next level—the time point of the type I IFN response orchestrates the immune response

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Cellular & Molecular Immunology 2020年第8期17卷 791-793页

作者： Angela Wedekind David Fritzsch Andrea kröger Research Group Molecular Microbiology Institute of Microbiology and Hospital HygieneOtto von Guericke University39120MagdeburgGermany Research Group Innate Immunity and Infection Helmholtz Centre for Infection Research38124BraunschweigGermany

The directed control of an effective cellular or adaptive immune response is the aim of vaccine strategies and tumor *** antibodies prevent the spread of pathogens,while efficient cellular immunotherapy is used to overcome T-cell exhaustion and unresponsiveness toward *** such settings,the type I interferon(IFN)system mediates pleiotropic effects of the immune system that can be either immunostimulating or *** a recent work,De Giovanni et *** a novel regulatory checkpoint by which type I IFN regulates CD4^(+)T-cell *** study dissects the time point of type I IFN induction as a central regulator of the adaptive immune response that determines the balance between humoral and cellular *** findings identify an intriguing and previously undescribed checkpoint that can potentially be manipulated for ***,the authors demonstrate that CD4^(+)T-cell polarization could be influenced by manipulating the IFN response during infection.

关键词： al. vaccine interferon

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Contribution of Fluid Dynamics to Woodwind Instruments Investigations of Timbre and Pitch of Bassoon Bocals

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Journal of Thermal Science 2005年第3期14卷 264-266页

作者： Roger GRUNDMANN Johannes BAUMGART Andreas RICHTER Hans krüger Technische Universitt Dresden Institute for Aerospace Engineering D-01062 Dresden Germany ProfessorTechnische Universitt Dresden Institute for Aerospace Engineering D-01062 Dresden GermanyTechnische Universitt Dresden Institute for Aerospace Engineering D-01062 Dresden GermanyTechnische Universit?t Dresden Institute for Aerospace Engineering D-01062 Dresden Germany

The discussed topic of isolating certain parameters which describe the timbre in connection with bocals of bassoons is of major interest for manufacturers and artist likewise since a reduction in the overall shear stress of these kinds of technical diffusors is very helpful but not sufficient. The timbre seen from the side of the musician has to be the same. Up to now two criteria have been isolated which have a deep influence on the easier blowing of the bassoon and on the comparable timbre due to geometrical reasons. If the geometrical outer contour is designed carefully, it is possible to modify the shape and preserve the timbre.

关键词： musical instrument bocal bassoon timbre principal component analysis

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Mitigation of atrazine,S-metolachlor,and diazinon using common emergent aquatic vegetation

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Journal of Environmental Sciences 2017年第6期29卷 114-121页

作者： Matthew T.Moore Martin A.Locke Robert krǒger Water Quality and Ecology Research Unit USDA Agricultural Research ServiceNational Sedimentation LaboratoryOxfordMS 38655USA

By the year 2050, the population of the United States is expected to reach over 418 million, while the global population will reach 9.6 billion. To provide safe food and fiber, agriculture must balance pesticide usage against impacts on natural resources. Challenges arise when storms cause runoff to be transported to aquatic receiving systems. Vegetated systems such as drainage ditches and constructed wetlands have been proposed as management practices to alleviate pesticide runoff. Twelve experimental mesocosms （1.3 ±0.71 ± 0.61 m） were filled with sediment and planted with a monoculture of one of three wetland plant species （Typha latifolia, Leersia oryzoides, and Sparganium arnericanurn）. Three mesocosms remained unvegetated to serve as controls. All mesocosms were amended with 9.2 ± 0.8 μg/L, 12 ± 0.4 μg/L, and 3.1 ± 0.2 μg/L of atrazine, metolachlor, and diazinon, respectively, over a 4 hr hydraulic retention time to simulate storm runoff. Following the 4 hr amendment, non-amended water was flushed through mesocosms for an additional 4 hr. Outflow water samples were taken hourly from pre-amendment through 8 hr, and again at 12, 24, 48, 72, and 168 hr post-amendment. L. oryzoides and T. latifolia had mean atrazine, metolachlor, and diazinon retentions from B1%-55% for the first 4 hr of the experiment. Aside from S. arnericanum and atrazine （25% retention）, unvegetated controls had the lowest pesticide retention （17%-28%） of all compared mesocosms. While native aquatic vegetation shows promise for mitigation of pesticide runoff, further studies increasing the hydraulic retention time for improved efficiency should be examined.

关键词： Phytoremediation Pesticide Mesocosm Wetland

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