The water drop penetration time(WDPT)test consists of placing water drops on a material's surface in order to evaluate how long it takes to penetrate the pores.It is used to evaluate the hydrophobicity of material...The water drop penetration time(WDPT)test consists of placing water drops on a material's surface in order to evaluate how long it takes to penetrate the pores.It is used to evaluate the hydrophobicity of materials.This study aims at investigating in more detail the soil-water interaction during the test,exposing its mechanism.For that,a model soil named Hamburg Sand was coated with a hydrophobic fluoropolymer and then a WDPT test was performed while computed tomography(CT)images were taken.Tomography experiments were performed at the P07 high-energy materials science(HEMS)beamline,operated by Helmholtz–Zentrum Hereon,at the storage ring PETRA III at the Deutsches Elektronen-Synchrotron(DESY)in Hamburg.Using synchrotron radiation,a tomogram can be obtained in about 10 min,way less time than regular laboratory X-ray sources usually owned by universities.The faster imaging enables the observation of the drop penetration during time and thus provides insight into the dynamics of the process.After that,digital discrete image correlation is performed to track the displacement of the grains throughout time.From the results one can observe that,as the drop is absorbed at the material's surface,the grains directly around the droplet base are dragged to the liquid-air interface around the drop,revealing grain kinematics during capillary interactions of the penetrating liquid and sand grains.展开更多
Magnesium(Mg)–based alloys are becoming attractive materials for medical applications as temporary bone implants for support of fracture healing,e.g.as a suture anchor.Due to their mechanical properties and biocompat...Magnesium(Mg)–based alloys are becoming attractive materials for medical applications as temporary bone implants for support of fracture healing,e.g.as a suture anchor.Due to their mechanical properties and biocompatibility,they may replace titanium or stainless-steel implants,commonly used in orthopedic field.Nevertheless,patient safety has to be assured by finding a long-term balance between metal degradation,osseointegration,bone ultrastructure adaptation and element distribution in organs.In order to determine the implant behavior and its influence on bone and tissues,we investigated two Mg alloys with gadolinium contents of 5 and 10 wt percent in comparison to permanent materials titanium and polyether ether ketone.The implants were present in rat tibia for 10,20 and 32 weeks before sacrifice of the animal.Synchrotron radiation-based micro computed tomography enables the distinction of features like residual metal,degradation layer and bone structure.Additionally,X-ray diffraction and X-ray fluorescence yield information on parameters describing the bone ultrastructure and elemental composition at the bone-to-implant interface.Finally,with element specific mass spectrometry,the elements and their accumulation in the main organs and tissues are traced.The results show that Mg-xGd implants degrade in vivo under the formation of a stable degradation layer with bone remodeling similar to that of Ti after 10 weeks.No accumulation of Mg and Gd was observed in selected organs,except for the interfacial bone after 8 months of healing.Thus,we confirm that Mg-5Gd and Mg-10Gd are suitable material choices for bone implants.展开更多
Magnesium(Mg)-based implants are highly attractive for the orthopedic field and may replace titanium(Ti)as support for fracture healing.To determine the implant-bone interaction in different bony regions,we implanted ...Magnesium(Mg)-based implants are highly attractive for the orthopedic field and may replace titanium(Ti)as support for fracture healing.To determine the implant-bone interaction in different bony regions,we implanted Mg-based alloy ZX00(Mg<0.5 Zn<0.5 Ca,in wt%)and Ti-screws into the distal epiphysis and distal metaphysis of sheep tibiae.The implant degradation and osseointegration were assessed in vivo and ex vivo after 4,6 and 12weeks,using a combination of clinical computed tomography,medium-resolution micro computed tomography(mCT)and high-resolution synchrotron radiation mCT(SRmCT).Implant volume loss,gas formation and bone growth were evaluated for both implantation sites and each bone region independently.Additionally,histological analysis of bone growth was performed on embedded hard-tissue samples.We demonstrate that in all cases,the degradation rate of ZX00-implants ranges between 0.23 and 0.75mm/year.The highest degradation rates were found in the epiphysis.Bone-to-implant contact varied between the time points and bone types for both materials.Mostly,bone-volume-to-total-volume was higher around Ti-implants.However,we found an increased cortical thickness around the ZX00-screws when compared with the Tiscrews.Our results showed the suitability of ZX00-screws for implantation into the distalmeta-and epiphysis.展开更多
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 stability.We present a study in which screw implants ...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 stability.We 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 implantation.Screws were 4 mm in length and with an M2 thread.The loading experiment was accompanied by simultaneous three-dimensional imaging using synchrotron-radiation microcomputed tomography at 5μm resolution.Bone deformation and strains were tracked by applying optical flow-based digital volume correlation to the recorded image sequences.Implant stabilities measured for screws of biodegradable alloys were comparable to pins whereas non-degradable biomaterials experienced additional mechanical stabilization.Peri-implant bone morphology and strain transfer from the loaded implant site depended heavily on the biomaterial utilized.Titanium 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 transfer.Correlations in our data suggest that implant stability benefits from disparate bone morphological properties depending on the biomaterial utilized.This leaves the choice of biomaterial as situational depending on local tissue properties.展开更多
基金funding of this research by the German Research Foundation(Deutsche Forschungsgemeinschaft,DFG)in the framework of Research Training Group GRK 2462:Processes in natural and technical Particle-Fluid-Systems at Hamburg University of Technology(TUHH).
文摘The water drop penetration time(WDPT)test consists of placing water drops on a material's surface in order to evaluate how long it takes to penetrate the pores.It is used to evaluate the hydrophobicity of materials.This study aims at investigating in more detail the soil-water interaction during the test,exposing its mechanism.For that,a model soil named Hamburg Sand was coated with a hydrophobic fluoropolymer and then a WDPT test was performed while computed tomography(CT)images were taken.Tomography experiments were performed at the P07 high-energy materials science(HEMS)beamline,operated by Helmholtz–Zentrum Hereon,at the storage ring PETRA III at the Deutsches Elektronen-Synchrotron(DESY)in Hamburg.Using synchrotron radiation,a tomogram can be obtained in about 10 min,way less time than regular laboratory X-ray sources usually owned by universities.The faster imaging enables the observation of the drop penetration during time and thus provides insight into the dynamics of the process.After that,digital discrete image correlation is performed to track the displacement of the grains throughout time.From the results one can observe that,as the drop is absorbed at the material's surface,the grains directly around the droplet base are dragged to the liquid-air interface around the drop,revealing grain kinematics during capillary interactions of the penetrating liquid and sand grains.
基金This publication is part of a project that has received funding from the European Union’s Horizon 2020 research and innovation program under the Marie Sk lodowska-Curie grant,agreement No 811226Röntgen-Angström Cluster in project SynchroLoad(05K16CGA)+5 种基金Swedish Research Council 2015-06109German Bundesministerium für Bildung und Forschung in project MgBone(05K16CGB)We acknowledge DESY(Hamburg,Germany),a member of the Helmholtz Association HGF,for the provision of experimental facilities.Parts of this research were carried out at PETRA IIIThe authors would like to thank Diamond Light Source for beamtime(proposal MG25078)Miguel Gomez Gonzalez and Julia Parker for assistance during the experiment at the I14 beamline and during the data analysisThis research was carried out in collaboration with the Quantitative Bio Element Analysis and Mapping(QBEAM)Center at Michigan State University and The National Research Resource for Quantitative Elemental Mapping for the Life Sciences(QE-Map)under Grant P41 GM135018(as well as Grant S10OD026786)from the National Institute of General Medical Sciences of the National Institutes of Health.
文摘Magnesium(Mg)–based alloys are becoming attractive materials for medical applications as temporary bone implants for support of fracture healing,e.g.as a suture anchor.Due to their mechanical properties and biocompatibility,they may replace titanium or stainless-steel implants,commonly used in orthopedic field.Nevertheless,patient safety has to be assured by finding a long-term balance between metal degradation,osseointegration,bone ultrastructure adaptation and element distribution in organs.In order to determine the implant behavior and its influence on bone and tissues,we investigated two Mg alloys with gadolinium contents of 5 and 10 wt percent in comparison to permanent materials titanium and polyether ether ketone.The implants were present in rat tibia for 10,20 and 32 weeks before sacrifice of the animal.Synchrotron radiation-based micro computed tomography enables the distinction of features like residual metal,degradation layer and bone structure.Additionally,X-ray diffraction and X-ray fluorescence yield information on parameters describing the bone ultrastructure and elemental composition at the bone-to-implant interface.Finally,with element specific mass spectrometry,the elements and their accumulation in the main organs and tissues are traced.The results show that Mg-xGd implants degrade in vivo under the formation of a stable degradation layer with bone remodeling similar to that of Ti after 10 weeks.No accumulation of Mg and Gd was observed in selected organs,except for the interfacial bone after 8 months of healing.Thus,we confirm that Mg-5Gd and Mg-10Gd are suitable material choices for bone implants.
基金supported by the European Training Network‘Promoting patient safety by a novel combination of imaging technologies for biodegradable magnesium implants,MgSafe’(Horizon 2020 Marie Skłodowska-Curie Action(MSCA)grant No.811226(www.mgsafe.eu))and the Laura Bassi Center of Expertise BRIC(Bioresorbable Implants for Children,FFG,Austria)This research was supported in part through the Maxwell computational resources operated at DESY。
文摘Magnesium(Mg)-based implants are highly attractive for the orthopedic field and may replace titanium(Ti)as support for fracture healing.To determine the implant-bone interaction in different bony regions,we implanted Mg-based alloy ZX00(Mg<0.5 Zn<0.5 Ca,in wt%)and Ti-screws into the distal epiphysis and distal metaphysis of sheep tibiae.The implant degradation and osseointegration were assessed in vivo and ex vivo after 4,6 and 12weeks,using a combination of clinical computed tomography,medium-resolution micro computed tomography(mCT)and high-resolution synchrotron radiation mCT(SRmCT).Implant volume loss,gas formation and bone growth were evaluated for both implantation sites and each bone region independently.Additionally,histological analysis of bone growth was performed on embedded hard-tissue samples.We demonstrate that in all cases,the degradation rate of ZX00-implants ranges between 0.23 and 0.75mm/year.The highest degradation rates were found in the epiphysis.Bone-to-implant contact varied between the time points and bone types for both materials.Mostly,bone-volume-to-total-volume was higher around Ti-implants.However,we found an increased cortical thickness around the ZX00-screws when compared with the Tiscrews.Our results showed the suitability of ZX00-screws for implantation into the distalmeta-and epiphysis.
文摘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 stability.We 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 implantation.Screws were 4 mm in length and with an M2 thread.The loading experiment was accompanied by simultaneous three-dimensional imaging using synchrotron-radiation microcomputed tomography at 5μm resolution.Bone deformation and strains were tracked by applying optical flow-based digital volume correlation to the recorded image sequences.Implant stabilities measured for screws of biodegradable alloys were comparable to pins whereas non-degradable biomaterials experienced additional mechanical stabilization.Peri-implant bone morphology and strain transfer from the loaded implant site depended heavily on the biomaterial utilized.Titanium 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 transfer.Correlations in our data suggest that implant stability benefits from disparate bone morphological properties depending on the biomaterial utilized.This leaves the choice of biomaterial as situational depending on local tissue properties.
