Mesoporous bioactive glasses have been widely investigated for applications in bone tissue regeneration and,more recently,in soft tissue repair and wound healing.In this study we produced mesoporous bioactive glass na...Mesoporous bioactive glasses have been widely investigated for applications in bone tissue regeneration and,more recently,in soft tissue repair and wound healing.In this study we produced mesoporous bioactive glass nanoparticles(MBGNs)based on the SiO2-CaO system.With the intention of adding subsidiary biological function,MBGNs were doped with Zn2+ions.Zn-MBGNs with 8 mol%ZnO content were synthesized via microemulsion assisted sol-gel method.The synthesized particles were homogeneous in shape and size.They exhibited spherical shape,good dispersity,and a size of 130±10 nm.The addition of zinc precursors did not affect the morphology of particles,while their specific surface area increased in comparison to MBGNs.The presence of Zn2+ions inhibited the formation of hydroxycarbonate apatite(HCAp)on the particles after immersion in simulated body fluid(SBF).No formation of HCAp crystals on the surface of Zn-MBGNs could be observed after 14 days of immersion.Interestingly,powders containing relatively high amount of zinc released Zn2+ions in low concentration(0.6-1.2 mg L^−1)but in a sustained manner.This releasing feature enables Zn-MBGNs to avoid potentially toxic levels of Zn2+ions,indeed Zn-MBGNs were seen to improve the differentiation of osteoblast-like cells(MG-63).Additionally,Zn-MBGNs showed higher ability to adsorb proteins in comparison to MBGNs,which could indicate a favourable later attachment of cells.Due to their advantageous morphological and physiochemical properties,Zn-MBGNs show great potential as bioactive fillers or drug delivery systems in a variety of applications including bone regeneration and wound healing.展开更多
The use of low-cost single GPS receivers and inertial sensors for auto-guidance applications has been limited by their reduced accuracy and signal drift over time compared to real-time kinematic(RTK)differential GPS u...The use of low-cost single GPS receivers and inertial sensors for auto-guidance applications has been limited by their reduced accuracy and signal drift over time compared to real-time kinematic(RTK)differential GPS units and fiber-optic gyroscope(FOG)sensors.In this study,a prototype low-cost GPS/INS integrated system consisting of a triangle-shaped array of three Garmin 19x GPS receivers and an Xsens inertial measurement unit(IMU)to improve the accuracy of position and heading angle measured with a single GPS receiver was developed.A triangular algorithm that uses data collected from the three single GPSs mounted on the angular points of a triangular frame was designed.A sensor fusion algorithm based on the Kalman filter combining the GPS and IMU data was developed by integrating position data and heading angles of a triangular array of GPS receivers.The optimized values of two noise covariance matrixes(Q and R)for the Kalman filtering were determined using the Central Composite Design(CCD)method.As compared to the use of a single Garmin GPS receiver,use of the developed GPS/INS system showed improved accuracy performance in terms of both position and heading angle,with reductions in root mean square errors(RMSEs)from 2.7 m to 0.64 m for position and from 8.9ºto 2.1ºfor heading angle.The accuracy improvements show new potential for agricultural auto-guidance applications.展开更多
A combination of the viscoelastic properties of hyaluronic acid(HA)and the elastic properties of star shaped 8-arm poly(ethylene glycol)(8-arm PEG)was used to design in-situ forming hydrogels.Hydrogels were prepared b...A combination of the viscoelastic properties of hyaluronic acid(HA)and the elastic properties of star shaped 8-arm poly(ethylene glycol)(8-arm PEG)was used to design in-situ forming hydrogels.Hydrogels were prepared by the enzymatic crosslinking of a partially tyramine modified 8-arm PEG and a tyramine conjugated HA using horseradish peroxidase in the presence of hydrogen peroxide.Hydrogels of the homopolymer conjugates and mixtures thereof were rapidly formed within seconds under physiological conditions at low polymer and enzyme concentrations.Elastic hydrogels with high gel content(≥95%)and high storage moduli(up to 22.4 kPa)were obtained.An in vitro study in the presence of hyaluronidase(100 U/mL)revealed that with increasing PEG content the degradation time of the hybrid hydrogels increased up to several weeks,whereas hydrogels composed of only hyaluronic acid degraded within 2 weeks.Human mesenchymal stem cells(hMSCs)incorporated in the hybrid hydrogels remained viable as shown by a PrestoBlue and a live-dead assay,confirming the biocompatibility of the constructs.The production of an extracellular matrix by re-differentiation of encapsulated human chondrocytes was followed over a period of 28 days.Gene expression indicated that these highly elastic hydrogels induced an enhanced production of collagen type II.At low PEG-TA/HA-TA ratios a higher expression of SOX 9 and ACAN was observed.These results indicate that by modulating the ratio of PEG/HA,injectable hydrogels can be prepared applicable as scaffolds for tissue regeneration applications.展开更多
The interface and surface properties of nano-hydroxyapatite(n-HA) and poly( 1, 4-phenylene sulfide)-poly (2,4-phenylene sulfide acid)(PPS-PPSA) copolymer composite were investigated. The results show that there are so...The interface and surface properties of nano-hydroxyapatite(n-HA) and poly( 1, 4-phenylene sulfide)-poly (2,4-phenylene sulfide acid)(PPS-PPSA) copolymer composite were investigated. The results show that there are some strong interface combinations of calcium ion (Ca2+ ), car-boxyl (-COO- ) and phosphate radicle ion (PO_4~3- ) between copolymer and n-HA in the composite. The presence of the 2,4-phenylene sulfide acid in copolymer can increase the affinity to n-HA, which causes the formation of chemical bindings between the PPS-PPSA copolymer and n-HA. XRD analysis and IR surface analysis indicate that n-HA is not encapsulated by copolymer but exposed on the surface of the composite, and has same structure and properties with the origi-nal n-HA. The presence of the interface chemical bindings between the PPS-PPSA copolymer and n-HA can increase the content of n-HA in composite but does not cause the decrease of the composite mechanical strength.展开更多
基金This project has received funding from the European Union's Horizon 2020 research and innovation program under grant agreement No 739566 and in the frame of the project Centre for Functional and Surface Functionalized Glass(CEGLASS)ITMS code is 313011R453,operational program Research and innovation,co-funded from European Regional Development FundThe financial support of this work by the grant VEGA 2/0026/17 and APVV 15/0014 is also gratefully acknowledged.
文摘Mesoporous bioactive glasses have been widely investigated for applications in bone tissue regeneration and,more recently,in soft tissue repair and wound healing.In this study we produced mesoporous bioactive glass nanoparticles(MBGNs)based on the SiO2-CaO system.With the intention of adding subsidiary biological function,MBGNs were doped with Zn2+ions.Zn-MBGNs with 8 mol%ZnO content were synthesized via microemulsion assisted sol-gel method.The synthesized particles were homogeneous in shape and size.They exhibited spherical shape,good dispersity,and a size of 130±10 nm.The addition of zinc precursors did not affect the morphology of particles,while their specific surface area increased in comparison to MBGNs.The presence of Zn2+ions inhibited the formation of hydroxycarbonate apatite(HCAp)on the particles after immersion in simulated body fluid(SBF).No formation of HCAp crystals on the surface of Zn-MBGNs could be observed after 14 days of immersion.Interestingly,powders containing relatively high amount of zinc released Zn2+ions in low concentration(0.6-1.2 mg L^−1)but in a sustained manner.This releasing feature enables Zn-MBGNs to avoid potentially toxic levels of Zn2+ions,indeed Zn-MBGNs were seen to improve the differentiation of osteoblast-like cells(MG-63).Additionally,Zn-MBGNs showed higher ability to adsorb proteins in comparison to MBGNs,which could indicate a favourable later attachment of cells.Due to their advantageous morphological and physiochemical properties,Zn-MBGNs show great potential as bioactive fillers or drug delivery systems in a variety of applications including bone regeneration and wound healing.
基金the Korea Evaluation Institute of Industrial Technology(10049017,2014-2016)Agricultural Robotics and Automation Research Center,Korea Institute of Planning and Evaluation for Technology in Food,Agriculture,Forestry and Fisheries(714002-7,2014-2016),Republic of Korea。
文摘The use of low-cost single GPS receivers and inertial sensors for auto-guidance applications has been limited by their reduced accuracy and signal drift over time compared to real-time kinematic(RTK)differential GPS units and fiber-optic gyroscope(FOG)sensors.In this study,a prototype low-cost GPS/INS integrated system consisting of a triangle-shaped array of three Garmin 19x GPS receivers and an Xsens inertial measurement unit(IMU)to improve the accuracy of position and heading angle measured with a single GPS receiver was developed.A triangular algorithm that uses data collected from the three single GPSs mounted on the angular points of a triangular frame was designed.A sensor fusion algorithm based on the Kalman filter combining the GPS and IMU data was developed by integrating position data and heading angles of a triangular array of GPS receivers.The optimized values of two noise covariance matrixes(Q and R)for the Kalman filtering were determined using the Central Composite Design(CCD)method.As compared to the use of a single Garmin GPS receiver,use of the developed GPS/INS system showed improved accuracy performance in terms of both position and heading angle,with reductions in root mean square errors(RMSEs)from 2.7 m to 0.64 m for position and from 8.9ºto 2.1ºfor heading angle.The accuracy improvements show new potential for agricultural auto-guidance applications.
基金support by a grant from the Dutch government to the Netherlands Institute for Regenerative Medicine(NIRM,Grant No.FES0908)support of the Netherlands Organisation for Scientific Research(NWO)P15-23(Project 1)“Activating resident stem cells”and EFRO OPOost 00867 Orthros TR.
文摘A combination of the viscoelastic properties of hyaluronic acid(HA)and the elastic properties of star shaped 8-arm poly(ethylene glycol)(8-arm PEG)was used to design in-situ forming hydrogels.Hydrogels were prepared by the enzymatic crosslinking of a partially tyramine modified 8-arm PEG and a tyramine conjugated HA using horseradish peroxidase in the presence of hydrogen peroxide.Hydrogels of the homopolymer conjugates and mixtures thereof were rapidly formed within seconds under physiological conditions at low polymer and enzyme concentrations.Elastic hydrogels with high gel content(≥95%)and high storage moduli(up to 22.4 kPa)were obtained.An in vitro study in the presence of hyaluronidase(100 U/mL)revealed that with increasing PEG content the degradation time of the hybrid hydrogels increased up to several weeks,whereas hydrogels composed of only hyaluronic acid degraded within 2 weeks.Human mesenchymal stem cells(hMSCs)incorporated in the hybrid hydrogels remained viable as shown by a PrestoBlue and a live-dead assay,confirming the biocompatibility of the constructs.The production of an extracellular matrix by re-differentiation of encapsulated human chondrocytes was followed over a period of 28 days.Gene expression indicated that these highly elastic hydrogels induced an enhanced production of collagen type II.At low PEG-TA/HA-TA ratios a higher expression of SOX 9 and ACAN was observed.These results indicate that by modulating the ratio of PEG/HA,injectable hydrogels can be prepared applicable as scaffolds for tissue regeneration applications.
文摘The interface and surface properties of nano-hydroxyapatite(n-HA) and poly( 1, 4-phenylene sulfide)-poly (2,4-phenylene sulfide acid)(PPS-PPSA) copolymer composite were investigated. The results show that there are some strong interface combinations of calcium ion (Ca2+ ), car-boxyl (-COO- ) and phosphate radicle ion (PO_4~3- ) between copolymer and n-HA in the composite. The presence of the 2,4-phenylene sulfide acid in copolymer can increase the affinity to n-HA, which causes the formation of chemical bindings between the PPS-PPSA copolymer and n-HA. XRD analysis and IR surface analysis indicate that n-HA is not encapsulated by copolymer but exposed on the surface of the composite, and has same structure and properties with the origi-nal n-HA. The presence of the interface chemical bindings between the PPS-PPSA copolymer and n-HA can increase the content of n-HA in composite but does not cause the decrease of the composite mechanical strength.
