The micro-CT imaging of vasculature is a powerful tool for evaluation of angiogenesis,a prominent characteristic of hepatic fibrosis.The segment or bifurcation density,which is usually adopted to evaluate the degree o...The micro-CT imaging of vasculature is a powerful tool for evaluation of angiogenesis,a prominent characteristic of hepatic fibrosis.The segment or bifurcation density,which is usually adopted to evaluate the degree of hepatic fibrosis,does not always work and may lead to incorrect assessment,especially when the threedimensional vasculature obtained is imperfect in sample preparation or image collection.In this paper,we propose a new parameter to solve this problem.The experimental results demonstrate that the method is robust and reliable,and is practical for angiogenesis evaluation,despite of image data imperfections.This quantitative analysis method can be extended to investigate other kinds of diseases in which vasculature change is a key indicator.展开更多
Several material parameters affect degradation characteristics of Mg and its alloys under physiological conditions.Porous Mg materials are interesting for their simultaneous degradation and drug delivery capabilities....Several material parameters affect degradation characteristics of Mg and its alloys under physiological conditions.Porous Mg materials are interesting for their simultaneous degradation and drug delivery capabilities.However,an increase in pore surface area is detrimental to both degradation resistance and subsequent mechanical properties.The 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 properties.Seven 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 supplements.The results are related to morphological pore parameters like pore size distribution,pore interconnectivity and pore curvatures that were quantified using an ex situμCT analysis.In general,with decreasing porosity a decrease in pore interconnectivity is seen followed by rounding of the pores.Low 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.This 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,respectively.The 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 properties.The results suggest that high pore interconnectivity is the dominant factor controlling degradation and mechanical properties in porous Mg-0.6 Ca specimens.The results also indicate a good sintering response of Mg-0.6 Ca specimens providing further material development towards biomaterial applications.展开更多
基金supported by the National Basic Research Program of China(No.2010CB834301)CAS-CSIRO Collaborative Research Project(GJHZ1303)+1 种基金the Shanghai Municipal Natural Science Foundation(No.11ZR1407800)the Joint Funds of the National Natural Science Foundation of China(Nos.U1232205,81430087 and81271574)
文摘The micro-CT imaging of vasculature is a powerful tool for evaluation of angiogenesis,a prominent characteristic of hepatic fibrosis.The segment or bifurcation density,which is usually adopted to evaluate the degree of hepatic fibrosis,does not always work and may lead to incorrect assessment,especially when the threedimensional vasculature obtained is imperfect in sample preparation or image collection.In this paper,we propose a new parameter to solve this problem.The experimental results demonstrate that the method is robust and reliable,and is practical for angiogenesis evaluation,despite of image data imperfections.This quantitative analysis method can be extended to investigate other kinds of diseases in which vasculature change is a key indicator.
基金funding from the Helmholtz Virtual Institute“In vivo studies of biodegradable magnesium based implant materials(Met Bio Mat)”under grant agreement no.VH-VI-523
文摘Several material parameters affect degradation characteristics of Mg and its alloys under physiological conditions.Porous Mg materials are interesting for their simultaneous degradation and drug delivery capabilities.However,an increase in pore surface area is detrimental to both degradation resistance and subsequent mechanical properties.The 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 properties.Seven 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 supplements.The results are related to morphological pore parameters like pore size distribution,pore interconnectivity and pore curvatures that were quantified using an ex situμCT analysis.In general,with decreasing porosity a decrease in pore interconnectivity is seen followed by rounding of the pores.Low 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.This 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,respectively.The 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 properties.The results suggest that high pore interconnectivity is the dominant factor controlling degradation and mechanical properties in porous Mg-0.6 Ca specimens.The results also indicate a good sintering response of Mg-0.6 Ca specimens providing further material development towards biomaterial applications.
