Critical bone defects are considered one of the major clinical challenges in reconstructive bone surgery.The combination of 3D printed conductive scaffolds and exogenous electrical stimulation(ES)is a potential favora...Critical bone defects are considered one of the major clinical challenges in reconstructive bone surgery.The combination of 3D printed conductive scaffolds and exogenous electrical stimulation(ES)is a potential favorable approach for bone tissue repair.In this study,3D conductive scaffolds made with biocompatible and biodegradable polycaprolactone(PCL)and multi-walled carbon nanotubes(MWCNTs)were produced using the extrusion-based additive manufacturing to treat large calvary bone defects in rats.Histology results show that the use of PCL/MWCNTs scaffolds and ES contributes to thicker and increased bone tissue formation within the bone defect.Angiogenesis and mineralization are also significantly promoted using high concentration of MWCNTs(3 wt%)and ES.Moreover,scaffolds favor the tartrate-resistant acid phosphatase(TRAP)positive cell formation,while the addition of MWCNTs seems to inhibit the osteoclastogenesis but present limited effects on the osteoclast functionalities(receptor activator of nuclear factor κβ ligand(RANKL)and osteoprotegerin(OPG)expressions).The use of ES promotes the osteoclastogenesis and RANKL expressions,showing a dominant effect in the bone remodeling process.These results indicate that the combination of 3D printed conductive PCL/MWCNTs scaffold and ES is a promising strategy to treat critical bone defects and provide a cue to establish an optimal protocol to use conductive scaffolds and ES for bone tissue engineering.展开更多
The paper deals with unusual use of one kind of ECA （electrically conductive adhesive）---the ICA （isotropic conductive adhesive）. The main sphere of ECA application is electronic assembly, e.g., it is bonding of s...The paper deals with unusual use of one kind of ECA （electrically conductive adhesive）---the ICA （isotropic conductive adhesive）. The main sphere of ECA application is electronic assembly, e.g., it is bonding of semiconductor microchips on printed circuits boards. In this sphere, the ECA compete with soft solder. In spite of this fact, the author utilized of two main ECA characteristics--good electrical conductivity and excellent adhesion to material surfaces to make the fiat thermocouples. Both the design of thermocouples and the measuring device and the measuring workplace arrangement are described. The measured data of thermoelectric voltages are plotted. The thermoelectric （Seebeck＇s） coefficients were calculated from obtained dependences of thermoelectric voltage versus the temperature differences.展开更多
The effects of contents of AlF3 and Al2O3, and temperature on electrical conductivity of （Na3AlF6-40%K3AlF6）- AlF3-Al2O3 were studied by continuously varying cell censtant （CVCC） technique. The results show that t...The effects of contents of AlF3 and Al2O3, and temperature on electrical conductivity of （Na3AlF6-40%K3AlF6）- AlF3-Al2O3 were studied by continuously varying cell censtant （CVCC） technique. The results show that the conductivities of melts increase with the increase of temperature, but by different extents. Every increasing 10 ℃ results in an increase of 1.85 × 10^-2, 1.86× 10^-2, 1.89 × 10^-2 and 2.20 × 10^-2 S/cm in conductivity for the （Na3AlF6-40%K3AlF6）-AlF3 melts containing 0%, 20%, 24%, and 30% AlF3, respectively. An increase of every 10 ℃ in temperature results an increase about 1.89× 10^-2, 1.94 × 10^-2, 1.95 × 10^-2, 1.99× 10^-2 and 2.10× 10^-2 S/cm for （Na3AlF6-40%K3AlF6）-AlF3-Al2O3 melts containing 0%, 1%, 2%, 3% and 4% Al2O3, respectively. The activation energy of conductance was calculated based on Arrhenius equation. Every increasing 1% of AlF3 results in a decrease of 0.019 and 0.020 S/cm in conductivity for （Na3AlF6-40%K3AlF6）-AlF3 melts at 900 and 1 000 ℃, respectively. Every increase of 1% Al2O3 results in a decrease of 0.07 S/cm in conductivity for （Na3AlF6-40%K3AlF6）-AlF3-Al2O3 melts. The activation energy of conductance increases with the increase in content of AlF3 and Al2O3.展开更多
A PGSTAT 30 and a BOOSTER 20A were used to measure cell impedance.Electrical conductivity was gained by the Continuously Varying Cell Constant Technique.Electrical conductivity of KCl was measured for comparison.The r...A PGSTAT 30 and a BOOSTER 20A were used to measure cell impedance.Electrical conductivity was gained by the Continuously Varying Cell Constant Technique.Electrical conductivity of KCl was measured for comparison.The results prove that the method is reliable and accurate.The electrical conductivity of Na3AlF6-AlF3-Al2O3-CaF2-LiF(NaCl)system was studied by this method.Activation energy of conductance was obtained based on the experiment results.The experiments show that electrical conductivity is increased greatly with NaCl and LiF added.Increasing 1%LiF(mass fraction)results in corresponding increase of 0.0276 S/cm for superheat condition of 15℃.For NaCl,it is 0.024 S/cm.Electrical conductivity is increased by 0.003 S/cm with 1℃temperature increase.The electrical conductivity is lower than that predicted by the WANG Model and higher than that predicted by the Choudhary Model.展开更多
Ceria-based electrolytes have been widely researched in intermediate-temperature solid oxide fuel cell （SOFC）, which might be operated at 500-600℃. Sintering behavior with lithium oxide as sintering additive and el...Ceria-based electrolytes have been widely researched in intermediate-temperature solid oxide fuel cell （SOFC）, which might be operated at 500-600℃. Sintering behavior with lithium oxide as sintering additive and electrical conductivity of gadolinia doped ceria （GdonCe0.902-σ, GDC10） electrolyte was studied in this paper by X-ray diffraction （XRD）, scanning electron microscopy （SEM） and electrochemical impedance spectroscopy （EIS）. As the results,, the fully dense GDC10 electrolytes are obtained at a low temperature of 800℃ with 2.5 mol% Li20 as sintering additive （called 5LiGDCS00）. During sintering process, lithium oxides adsorbed by around GDC10 surface help to sinter at 800~C and are kept at the grain boundary of GDC10 in the end. The fine grains of 100-400 nm and high electrical conductivity of 0.014 S/cm at 600~C in 5LiGDC800 were achieved, which contributed to the lower sintering temperature and enhanced grain boundary conductivity, respectively. Lithium, staying at grain boundary, reduces the depletion of oxygen vacancies in the space charge layers and increases the oxygen vacancy concentration in the grain boundary, which leads to improve the total electrical conductivity of 5LiGDC800.展开更多
基金supported by the University of Manchester/King Saud University research grant“Multi scale bioactive scaffolds for bone regeneration”project and the Engineering and Physical Sciences Research Council,the Global Challenges Research Fund(CRF),grant number EP/R01513/1this project is also financially supported by University Center of Hermínio Ometto Foundation-FHO and CNPq(“Conselho Nacional do desenvolvimento Científico e Tecnológico”)grant number 423710/2018-4.
文摘Critical bone defects are considered one of the major clinical challenges in reconstructive bone surgery.The combination of 3D printed conductive scaffolds and exogenous electrical stimulation(ES)is a potential favorable approach for bone tissue repair.In this study,3D conductive scaffolds made with biocompatible and biodegradable polycaprolactone(PCL)and multi-walled carbon nanotubes(MWCNTs)were produced using the extrusion-based additive manufacturing to treat large calvary bone defects in rats.Histology results show that the use of PCL/MWCNTs scaffolds and ES contributes to thicker and increased bone tissue formation within the bone defect.Angiogenesis and mineralization are also significantly promoted using high concentration of MWCNTs(3 wt%)and ES.Moreover,scaffolds favor the tartrate-resistant acid phosphatase(TRAP)positive cell formation,while the addition of MWCNTs seems to inhibit the osteoclastogenesis but present limited effects on the osteoclast functionalities(receptor activator of nuclear factor κβ ligand(RANKL)and osteoprotegerin(OPG)expressions).The use of ES promotes the osteoclastogenesis and RANKL expressions,showing a dominant effect in the bone remodeling process.These results indicate that the combination of 3D printed conductive PCL/MWCNTs scaffold and ES is a promising strategy to treat critical bone defects and provide a cue to establish an optimal protocol to use conductive scaffolds and ES for bone tissue engineering.
文摘The paper deals with unusual use of one kind of ECA （electrically conductive adhesive）---the ICA （isotropic conductive adhesive）. The main sphere of ECA application is electronic assembly, e.g., it is bonding of semiconductor microchips on printed circuits boards. In this sphere, the ECA compete with soft solder. In spite of this fact, the author utilized of two main ECA characteristics--good electrical conductivity and excellent adhesion to material surfaces to make the fiat thermocouples. Both the design of thermocouples and the measuring device and the measuring workplace arrangement are described. The measured data of thermoelectric voltages are plotted. The thermoelectric （Seebeck＇s） coefficients were calculated from obtained dependences of thermoelectric voltage versus the temperature differences.
基金Project(2005CB623703) supported by the Major State Basic Research and Development Program of ChinaProject(2008AA030503) supported by the National High-Tech Research and Development Program of ChinaProject(GUIKEJI 0639032) supported by Applied Basic Research in Guangxi Province, China
文摘The effects of contents of AlF3 and Al2O3, and temperature on electrical conductivity of （Na3AlF6-40%K3AlF6）- AlF3-Al2O3 were studied by continuously varying cell censtant （CVCC） technique. The results show that the conductivities of melts increase with the increase of temperature, but by different extents. Every increasing 10 ℃ results in an increase of 1.85 × 10^-2, 1.86× 10^-2, 1.89 × 10^-2 and 2.20 × 10^-2 S/cm in conductivity for the （Na3AlF6-40%K3AlF6）-AlF3 melts containing 0%, 20%, 24%, and 30% AlF3, respectively. An increase of every 10 ℃ in temperature results an increase about 1.89× 10^-2, 1.94 × 10^-2, 1.95 × 10^-2, 1.99× 10^-2 and 2.10× 10^-2 S/cm for （Na3AlF6-40%K3AlF6）-AlF3-Al2O3 melts containing 0%, 1%, 2%, 3% and 4% Al2O3, respectively. The activation energy of conductance was calculated based on Arrhenius equation. Every increasing 1% of AlF3 results in a decrease of 0.019 and 0.020 S/cm in conductivity for （Na3AlF6-40%K3AlF6）-AlF3 melts at 900 and 1 000 ℃, respectively. Every increase of 1% Al2O3 results in a decrease of 0.07 S/cm in conductivity for （Na3AlF6-40%K3AlF6）-AlF3-Al2O3 melts. The activation energy of conductance increases with the increase in content of AlF3 and Al2O3.
基金Project(50334030)supported by the National Natural Science Foundation of China
文摘A PGSTAT 30 and a BOOSTER 20A were used to measure cell impedance.Electrical conductivity was gained by the Continuously Varying Cell Constant Technique.Electrical conductivity of KCl was measured for comparison.The results prove that the method is reliable and accurate.The electrical conductivity of Na3AlF6-AlF3-Al2O3-CaF2-LiF(NaCl)system was studied by this method.Activation energy of conductance was obtained based on the experiment results.The experiments show that electrical conductivity is increased greatly with NaCl and LiF added.Increasing 1%LiF(mass fraction)results in corresponding increase of 0.0276 S/cm for superheat condition of 15℃.For NaCl,it is 0.024 S/cm.Electrical conductivity is increased by 0.003 S/cm with 1℃temperature increase.The electrical conductivity is lower than that predicted by the WANG Model and higher than that predicted by the Choudhary Model.
基金supported by the National Natural Science Foundation of China (Grant No. 50730004)the Ministry of Science and Technology of the People’s Republic of China (No. 2009DFA6136)
文摘Ceria-based electrolytes have been widely researched in intermediate-temperature solid oxide fuel cell （SOFC）, which might be operated at 500-600℃. Sintering behavior with lithium oxide as sintering additive and electrical conductivity of gadolinia doped ceria （GdonCe0.902-σ, GDC10） electrolyte was studied in this paper by X-ray diffraction （XRD）, scanning electron microscopy （SEM） and electrochemical impedance spectroscopy （EIS）. As the results,, the fully dense GDC10 electrolytes are obtained at a low temperature of 800℃ with 2.5 mol% Li20 as sintering additive （called 5LiGDCS00）. During sintering process, lithium oxides adsorbed by around GDC10 surface help to sinter at 800~C and are kept at the grain boundary of GDC10 in the end. The fine grains of 100-400 nm and high electrical conductivity of 0.014 S/cm at 600~C in 5LiGDC800 were achieved, which contributed to the lower sintering temperature and enhanced grain boundary conductivity, respectively. Lithium, staying at grain boundary, reduces the depletion of oxygen vacancies in the space charge layers and increases the oxygen vacancy concentration in the grain boundary, which leads to improve the total electrical conductivity of 5LiGDC800.
