To assess a novel cell manipulation technique of tissue engineering with respect to its ability to augment superparamagnetic iron oxide particles （SPIO） labeled mesenchymal stem cells （MSCs） density at a localized...To assess a novel cell manipulation technique of tissue engineering with respect to its ability to augment superparamagnetic iron oxide particles （SPIO） labeled mesenchymal stem cells （MSCs） density at a localized cartilage defect site in an in vitro phantom by applying magnetic force. Meanwhile, non-invasive imaging techniques were use to track SPIO-labeled MSCs by magnetic resonance imaging （MRI）. Human bone marrow MSCs were cultured and labeled with SPIO. Fresh degenerated human osteochondral fragments were obtained during total knee arthroplasty and a cartilage defect was created at the center. Then, the osteochondral fragments were attached to the sidewalls of culture flasks filled with phosphate-buffered saline （PBS） to mimic the human joint cavity. The SPIO-labeled MSCs were injected into the culture flasks in the presence of a 0.57 Tesla （T） magnetic force. Before and 90 min after cell targeting, the specimens underwent T2-weighted turbo spin-echo （SET2WI） sequence of 3.0 T MRI. MRI results were compared with histological findings. Macroscopic observation showed that SPIO-labeled MSCs were steered to the target region of cartilage defect. MRI revealed significant changes in signal intensity （P0.01）. HE staining exibited that a great number of MSCs formed a three-dimensional （3D） cell ＂sheet＂ structure at the chondral defect site. It was concluded that 0.57 T magnetic force permits spatial delivery of magnetically labeled MSCs to the target region in vitro. High-field MRI can serve as an very sensitive non-invasive technique for the visualization of SPIO-labeled MSCs.展开更多
Ultrafine particle (UFP)alumina has been prepared by supereritical fluid drying process of inorganic salt with organic solvent system, which is reported for the first time. UFP-alumina prepared from this system is fea...Ultrafine particle (UFP)alumina has been prepared by supereritical fluid drying process of inorganic salt with organic solvent system, which is reported for the first time. UFP-alumina prepared from this system is featured by its hish specific surface area, large pore volume, small perticle size and low bulk density.展开更多
Nickel was deposited by ac electrolysis deposition in the pores of the porous oxide film of Al produced by anodizing in phosphoric acid. Ultrafine rod-shaped Ni particles were formed in the pores. At the same time a f...Nickel was deposited by ac electrolysis deposition in the pores of the porous oxide film of Al produced by anodizing in phosphoric acid. Ultrafine rod-shaped Ni particles were formed in the pores. At the same time a film of Ni oxide precursor was developed on the surface of the porous oxide film. The Ni particles and the Ni oxide precursor were examined by SEM, TEM and X-ray diffraction. The thickness of the barrier layer of the porous oxide film was thin and it attributed to the formation of the metal particles, while the formation of the oxide precursor was associated with the surface pits which were developed in the pretreatment of Al.展开更多
An oxide-dispersion-strengthened(ODS)Fe-10Cr-6.1Al-0.3Zr-0.1Y alloy with a bimodal grain size distribution was developed via a simple process of internal oxidation and powder forging.The intentionally promoted heterog...An oxide-dispersion-strengthened(ODS)Fe-10Cr-6.1Al-0.3Zr-0.1Y alloy with a bimodal grain size distribution was developed via a simple process of internal oxidation and powder forging.The intentionally promoted heterogeneous microstructure consists of coarse-grained“core”regions enclosed by mutually connected fine-grained“shell”zones,facilitated by unevenly distributed oxide particles.The sample sintered and then forged at 1150℃exhibited a yield strength of 598 MPa,a tensile strength of 734 MPa,and a fracture elongation of 25.1%.Such simultaneously enhanced strength and ductility are significantly above those of cast or previous powder-consolidated counterparts.During tensile deformation,a strain gradient is built up across the inhomogeneous grains and a high density of geometrically necessary dis-locations was observed near the interfaces of matrix/oxide particles,both contributing to heterogeneous deformation-induced strengthening.This elevates the work hardening rate and consequently the tensile elongation.Quantitative analysis indicates that the dislocation build-up during forging makes the dom-inant contribution to the high yield strength of Ox-1150.The present study offers a new route to the preparation of heterogeneously structured ODS Fe-Cr-Al alloys and provides guidance for optimizing the mechanical properties of such alloys in terms of strength-ductility synergy.展开更多
Two continuously regenerating diesel particulate filter （CRDPF） with different configurations and one particles oxidation catalyst （POC） were employed to perform experiments in a controlled laboratory setting to e...Two continuously regenerating diesel particulate filter （CRDPF） with different configurations and one particles oxidation catalyst （POC） were employed to perform experiments in a controlled laboratory setting to evaluate their effects on NO2, smoke and particle number emissions. The results showed that the application of the after-treatments increased the emission ratios of NO2/NOx significantly. The results of smoke emissions and particle number （PN） emissions indicated that both CRDPFs had sufficient capacity to remove more than 90% of total particulate matter （PM） and more than 97% of solid particles. However, the POC was able to remove the organic components of total PM, and only partially to remove the carbonaceous particles with size less than 30 nm. The negligible effects of POC on larger particles were observed due to its honeycomb structure leads to an inadequate residence time to oxidize the solid particles or trap them. The particles removal efficiencies of CRDPFs had high degree of correlations with the emission ratio of NO2/NOx. The PN emission results from two CRDPFs indicated that more NO2 generating in diesel oxidation catalyst section could obtain the higher removal efficiency of solid particles. However this also increased the risk of NO2 exposure in atmosphere.展开更多
The oxidation of SO2 is commonly regarded as a major driver for new particle formation（NPF） in the atmosphere. In this study, we explored the connection between measured mixing ratio of SO2 and observed long-term（d...The oxidation of SO2 is commonly regarded as a major driver for new particle formation（NPF） in the atmosphere. In this study, we explored the connection between measured mixing ratio of SO2 and observed long-term（duration 〉 3 hr） and short-term（duration〈 1.5 hr） NPF events at a semi-urban site in Toronto. Apparent NPF rates（J30） showed a moderate correlation with the concentration of sulfuric acid（[H2SO4]） calculated from the measured mixing ratio of SO2 in long-term NPF events and some short-term NPF events（Category I）（R^2= 0.66）. The exponent in the fitting line of J30~ [H2SO4]nin these events was1.6. It was also found that SO2 mixing ratios varied a lot during long-term NPF events,leading to a significant variation of new particle counts. In the SO2-unexplained short-term NPF events（Category II）, analysis showed that new particles were formed aloft and then mixed down to the ground level. Further calculation results showed that sulfuric acid oxidized from SO2 probably made a negligible contribution to the growth of 〉 10 nm new particles.展开更多
Background Angiogenesis is an essential step for tumor development and metastasis.The cell adhesion molecule αvβ3 integrin plays an important role in angiogenesis and is a specific marker of tumor angiogenesis.A nov...Background Angiogenesis is an essential step for tumor development and metastasis.The cell adhesion molecule αvβ3 integrin plays an important role in angiogenesis and is a specific marker of tumor angiogenesis.A novel αvβ3 integrintargeted magnetic resonance （MR） imaging contrast agent utilizing Arg-Gly-Asp （RGD） and ultrasmall superparamagnetic iron oxide particles （USPIO） （referred to as RGD-USPIO） was designed and its uptake by endothelial cells was assessed both in vitro and in vivo to evaluate the angiogenic profile of lung cancer.Methods USPIO were coated with-NH3＋ and conjugated with RGD peptides.Prussian blue staining was performed to evaluate the specific uptake of RGD-USPIO by human umbilical vein endothelial cells （HUVECs）.Targeted uptake and subcellular localization of RGD-USPIO in HUVECs were confirmed by transmission electron microscopy （TEM）.The ability of RGD-USPIO to noninvasively assess αvβ3 integrin positive vessels in lung adenocarcinoma A549 tumor xenografts was evaluated with a 4.7T MR scanner.Immunohistochemistry was used to detect αvβ3 integrin expression and vessel distribution in A549 tumor xenografts.Results HUVECs internalized RGD-USPIO significantly more than plain USPIO.The uptake of RGD-USPIO by HUVECs could be competitively inhibited by addition of free RGD.A significant decrease in T2 signal intensity （SI） was observed at the periphery of A549 tumor xenografts at 30 minutes （P 〈0.05） and 2 hours （P 〈0.01） after RGD-USPIO was injected via the tail vein.Angiogenic blood vessels were mainly distributed in the periphery of tumor xenografts with positive αvβ3 integrin expression.Conclusions RGD-USPIO could specifically label αvβ3 integrin and be taken up by HUVECs.This molecular MR imaging contrast agent can specifically evaluate the angiogenic profile of lung cancer using a 4.7T MR scanner.展开更多
A composite coating containing hexagonal boron nitride（hBN） particles and titanium oxide（TiO_2） was formed on the surface of Ti-6Al-4V alloy via micro-arc oxidation（MAO）. The effect of quantity of the hBN-partic...A composite coating containing hexagonal boron nitride（hBN） particles and titanium oxide（TiO_2） was formed on the surface of Ti-6Al-4V alloy via micro-arc oxidation（MAO）. The effect of quantity of the hBN-particles added into electrolyte on microstructure, composition, and wear behavior of the resulting composite coatings was investigated. Microstructure, phase composition, and tribological behavior of the resulting MAO coatings were evaluated via scanning electron microscopy, X-ray diffraction, and ball-on-disc abrasive tests. The results reveal that the TiO_2/hBN composite coating consisting of rutile TiO_2, anatase TiO_2, and an hBN phase was less porous than particle-free coating. Furthermore, the presence of hBN particles in the MAO coating produced an improved anti-friction property. The composite coating produced in the electrolyte containing 2 g/L of hBN particles exhibited the best wear resistance.The outer loose layer of the MAO coatings was removed by a mechanical polishing process, which led to a significant improvement in the wear resistance and anti-friction properties of the MAO coatings and highlighted an essential lubricating role of hBN particles in the composite coatings. However, wear mechanism of the MAO coatings was not relevant to the presence of hBN particles, where fatigue wear dominated the anti-fraction properties of the MAO coatings with and without hBN particles.展开更多
The electrochemical behavior of the 3-(4-N-pyridine-2-yl benzene sulfonamide azo)-1-nitroso naphthol reagent and its complex with Co(II)has been studied at glassy carbon disk electrode in different supporting electrol...The electrochemical behavior of the 3-(4-N-pyridine-2-yl benzene sulfonamide azo)-1-nitroso naphthol reagent and its complex with Co(II)has been studied at glassy carbon disk electrode in different supporting electrolyte at concentration 1 mol and scan rate(100 mV/s).3-(4-N-pyridine-2-yl benzene sulfonamide azo)-1-nitroso naphthol was used for enhance the properties of nano cobalt oxide by ligand exchange reaction on nanoparticles.展开更多
The coupled CFD-DEM simulations are widely recognized as a powerful approach for analyzing various particle-fluid systems.In lead-bismuth nuclear reactors,the liquid lead-bismuth eutectic(LBE)alloy is employed as the ...The coupled CFD-DEM simulations are widely recognized as a powerful approach for analyzing various particle-fluid systems.In lead-bismuth nuclear reactors,the liquid lead-bismuth eutectic(LBE)alloy is employed as the coolant,and the solid-phase oxygen control is a key technique for corrosion mitigation.In this work,diffusive smoothing CFD-DEM simulations are performed to investigate the particle-scale mass transfer behaviors of LBE solid-phase oxygen control loops.The dissolution of the lead oxide particle within the mass exchanger serves as the source term of the mass transfer processes.In the current model,the fluid flow,particle motion,particle-fluid interaction forces,and the mass transfer of oxygen concentration in LBE are incorporated in the governing equations.When the CFD cell size is smaller than the particle diameter,the diffusive smoothing method is proposed to calculate the void fraction field.Compared with the experimental results,the numerical simulations give a satisfactory prediction of the flow dynamics and particle-scale mass transfer.In the small-sized experiment,the total dissolution rate is about 0.0031 g/h at 380 C,and it is notably lower than the oxygen consumption in a full-scale megawatt-level lead-bismuth reactor.A large-scale mass exchanger is designed,and the numerical simulations indicate that the oxygen control system achieves a dissolution rate ranging from 5.28 to 23.74 g/h at temperatures of 380-420℃.It is sufficient to meet the expected oxygen consumption of 4.5 g/h in the nuclear reactor.The diffusive smoothing CFD-DEM approach provides a robust tool for the design and optimization of oxygen control loops of advanced lead-bismuth fast nuclear reactors.展开更多
In this study,the functional gradient materials(FGMs)were the first attempt to homogenise the electric field distribution in the cable accessory,where zinc oxide particles(ZnO_(k))were filled into ethylene propylene d...In this study,the functional gradient materials(FGMs)were the first attempt to homogenise the electric field distribution in the cable accessory,where zinc oxide particles(ZnO_(k))were filled into ethylene propylene diene monomer with the composi-tionally gradient distribution using laminating and hot-pressing methods.The constructed FGMs with significantly improved non-linear conductivity can avoid the electric field distortion in cable accessories.The results show that the configuration of compositionally gradient structured fillers can significantly improve the electrical conductivity of FGMs compared to the homogeneous distribution.Additionally,compositionally gradient structures of ZnOk fillers can also improve the thermal conductivity of FGM composites,which facilitates the heat dissipation of dielectric and reduces the probability of electrothermal coupling breakdown.The mechanical properties of the composites are deeply affected by the filler's content and configuration,both improved tear elongation and tensile strength can be achieved at an optimal content and gradient structure of ZnOk fillers.Finally,the simulation analysis results show that FGM composites can homogenise the electric field more efficiently in comparison with homogeneous composites.This work demonstrates that compositionally gradient structures can improve the utilisation of functional fillers and develop the FGM composites for high-voltage direct current cable accessory applications.展开更多
Wide-angle light scattering(WALS)was used for in situ measurements of droplet and nanoparticle size distributions during the synthesis of titania and iron oxide particles from liquid precursor solutions in the standar...Wide-angle light scattering(WALS)was used for in situ measurements of droplet and nanoparticle size distributions during the synthesis of titania and iron oxide particles from liquid precursor solutions in the standardized SpraySyn burner for spray flame synthesis.Titania was synthesized from titanium tetraisopropoxide(TTIP)and iron oxide from iron(II)nitrate nonahydrate(INN)using ethanol(EtOH)as solvent.Scattering images were taken at heights up to 120 mm above the burner surface and classified into droplet and particle scattering.Droplet size distributions were derived from a sequential analysis of scattering data containing the oscillating Mie pattern,the lognormal size distribution parameters for spherical and fractal particle fractions from a multivariate approach on averaged particle scattering data.The results show that the precursor addition leads to altered evaporation behavior and even droplet disruption probably induced by puffing or micro-explosions compared to pure EtOH.In the case of TTIP(a hygroscopic alkoxide),the synthesis of a large fraction of spheres was observed,while the nitrate INN leads to the formation of mostly fractal aggregates.展开更多
The effect of non-Gaussian colored noise(NGN),mainly its departure q from the Gaussian noise,on the optimal ISRO of CO oxidation on nanometer-sized Pd particles was studied.It was found that the ISRO in the absence of...The effect of non-Gaussian colored noise(NGN),mainly its departure q from the Gaussian noise,on the optimal ISRO of CO oxidation on nanometer-sized Pd particles was studied.It was found that the ISRO in the absence of external noise can still be enhanced when the NGN is applied.Specifically,the ISRO varies with changing q and becomes more regular at an appropriate q value,and when q is optimal,the ISRO becomes the most regular.Because the departure q from the Gaussian noise determines the probability distribution function and hence may denote the types of noise,this result shows that different types of external noise can enhance the ISRO of CO oxidation,and non-Gaussian noise may enhance the ISRO more greatly than the Gaussian noise.Therefore,non-Gaussian noise could play more effective roles in the catalytic process of CO oxidation on nanometer-sized Pd particles.展开更多
Background Previously we had successfully tracked adult human neural stem cells （NSCs） labeled with superparamagnetic iron oxide particles （SPIOs） in host human brain after transplantation in vivo non-invasively b...Background Previously we had successfully tracked adult human neural stem cells （NSCs） labeled with superparamagnetic iron oxide particles （SPIOs） in host human brain after transplantation in vivo non-invasively by magnetic resonance imaging （MRI）. However, the function of the transplanted NSCs could not be evaluated by the method. In the study, we applied manganese-enhanced MRI （ME-MRI） to detect NSCs function after implantation in brain of rats with traumatic brain injury （TBI） in vivo. Methods Totally 40 TBI rats were randomly divided into 4 groups with 10 rats in each group. In group 1, the TBI rats did not receive NSCs transplantation. MnCI2＂4H20 was intravenously injected, hyperosmolar mannitol was delivered to disrupt rightside blood brain barrier, and its contralateral forepaw was electrically stimulated. In group 2, the TBI rats received NSCs （labeled with SPIO） transplantation, and the ME-MRI procedure was same to group 1. In group 3, the TBI rats received NSCs （labeled with SPIO） transplantation, and the ME-MRI procedure was same to group 1, but diltiazem was introduced during the electrical stimulation period. In group 4, the TBI rats received phosphate buffered saline （PBS） injection, and the ME-MRI procedure was same to group 1. Results Hyperintense signals were detected by ME-MRI in the cortex areas associated with somatosensory in TBI rats of group 2. These signals, which could not be induced in TBI rats of groups 1 and 4, disappeared when diltiazem was introduced in TBI rats of group 3. Conclusion In this initial study, we mapped implanted NSCs activity and its functional participation within local brain area in TBI rats by ME-MRI technique, paving the way for further pre-clinical research.展开更多
基金supported by a grant from the National Natural Sciences Foundation of China (No. 30870639)
文摘To assess a novel cell manipulation technique of tissue engineering with respect to its ability to augment superparamagnetic iron oxide particles （SPIO） labeled mesenchymal stem cells （MSCs） density at a localized cartilage defect site in an in vitro phantom by applying magnetic force. Meanwhile, non-invasive imaging techniques were use to track SPIO-labeled MSCs by magnetic resonance imaging （MRI）. Human bone marrow MSCs were cultured and labeled with SPIO. Fresh degenerated human osteochondral fragments were obtained during total knee arthroplasty and a cartilage defect was created at the center. Then, the osteochondral fragments were attached to the sidewalls of culture flasks filled with phosphate-buffered saline （PBS） to mimic the human joint cavity. The SPIO-labeled MSCs were injected into the culture flasks in the presence of a 0.57 Tesla （T） magnetic force. Before and 90 min after cell targeting, the specimens underwent T2-weighted turbo spin-echo （SET2WI） sequence of 3.0 T MRI. MRI results were compared with histological findings. Macroscopic observation showed that SPIO-labeled MSCs were steered to the target region of cartilage defect. MRI revealed significant changes in signal intensity （P0.01）. HE staining exibited that a great number of MSCs formed a three-dimensional （3D） cell ＂sheet＂ structure at the chondral defect site. It was concluded that 0.57 T magnetic force permits spatial delivery of magnetically labeled MSCs to the target region in vitro. High-field MRI can serve as an very sensitive non-invasive technique for the visualization of SPIO-labeled MSCs.
文摘Ultrafine particle (UFP)alumina has been prepared by supereritical fluid drying process of inorganic salt with organic solvent system, which is reported for the first time. UFP-alumina prepared from this system is featured by its hish specific surface area, large pore volume, small perticle size and low bulk density.
基金National Natural Science Foundation of China!No. 59774031
文摘Nickel was deposited by ac electrolysis deposition in the pores of the porous oxide film of Al produced by anodizing in phosphoric acid. Ultrafine rod-shaped Ni particles were formed in the pores. At the same time a film of Ni oxide precursor was developed on the surface of the porous oxide film. The Ni particles and the Ni oxide precursor were examined by SEM, TEM and X-ray diffraction. The thickness of the barrier layer of the porous oxide film was thin and it attributed to the formation of the metal particles, while the formation of the oxide precursor was associated with the surface pits which were developed in the pretreatment of Al.
基金supported by the Innovative Scientific Program of CNNC(No.J202107006-02).
文摘An oxide-dispersion-strengthened(ODS)Fe-10Cr-6.1Al-0.3Zr-0.1Y alloy with a bimodal grain size distribution was developed via a simple process of internal oxidation and powder forging.The intentionally promoted heterogeneous microstructure consists of coarse-grained“core”regions enclosed by mutually connected fine-grained“shell”zones,facilitated by unevenly distributed oxide particles.The sample sintered and then forged at 1150℃exhibited a yield strength of 598 MPa,a tensile strength of 734 MPa,and a fracture elongation of 25.1%.Such simultaneously enhanced strength and ductility are significantly above those of cast or previous powder-consolidated counterparts.During tensile deformation,a strain gradient is built up across the inhomogeneous grains and a high density of geometrically necessary dis-locations was observed near the interfaces of matrix/oxide particles,both contributing to heterogeneous deformation-induced strengthening.This elevates the work hardening rate and consequently the tensile elongation.Quantitative analysis indicates that the dislocation build-up during forging makes the dom-inant contribution to the high yield strength of Ox-1150.The present study offers a new route to the preparation of heterogeneously structured ODS Fe-Cr-Al alloys and provides guidance for optimizing the mechanical properties of such alloys in terms of strength-ductility synergy.
基金supported by the National Natural Science Foundation of China (No. 50876013)
文摘Two continuously regenerating diesel particulate filter （CRDPF） with different configurations and one particles oxidation catalyst （POC） were employed to perform experiments in a controlled laboratory setting to evaluate their effects on NO2, smoke and particle number emissions. The results showed that the application of the after-treatments increased the emission ratios of NO2/NOx significantly. The results of smoke emissions and particle number （PN） emissions indicated that both CRDPFs had sufficient capacity to remove more than 90% of total particulate matter （PM） and more than 97% of solid particles. However, the POC was able to remove the organic components of total PM, and only partially to remove the carbonaceous particles with size less than 30 nm. The negligible effects of POC on larger particles were observed due to its honeycomb structure leads to an inadequate residence time to oxidize the solid particles or trap them. The particles removal efficiencies of CRDPFs had high degree of correlations with the emission ratio of NO2/NOx. The PN emission results from two CRDPFs indicated that more NO2 generating in diesel oxidation catalyst section could obtain the higher removal efficiency of solid particles. However this also increased the risk of NO2 exposure in atmosphere.
基金the National Natural Science Foundation of China (No. 41176099, No. 41306101)
文摘The oxidation of SO2 is commonly regarded as a major driver for new particle formation（NPF） in the atmosphere. In this study, we explored the connection between measured mixing ratio of SO2 and observed long-term（duration 〉 3 hr） and short-term（duration〈 1.5 hr） NPF events at a semi-urban site in Toronto. Apparent NPF rates（J30） showed a moderate correlation with the concentration of sulfuric acid（[H2SO4]） calculated from the measured mixing ratio of SO2 in long-term NPF events and some short-term NPF events（Category I）（R^2= 0.66）. The exponent in the fitting line of J30~ [H2SO4]nin these events was1.6. It was also found that SO2 mixing ratios varied a lot during long-term NPF events,leading to a significant variation of new particle counts. In the SO2-unexplained short-term NPF events（Category II）, analysis showed that new particles were formed aloft and then mixed down to the ground level. Further calculation results showed that sulfuric acid oxidized from SO2 probably made a negligible contribution to the growth of 〉 10 nm new particles.
文摘Background Angiogenesis is an essential step for tumor development and metastasis.The cell adhesion molecule αvβ3 integrin plays an important role in angiogenesis and is a specific marker of tumor angiogenesis.A novel αvβ3 integrintargeted magnetic resonance （MR） imaging contrast agent utilizing Arg-Gly-Asp （RGD） and ultrasmall superparamagnetic iron oxide particles （USPIO） （referred to as RGD-USPIO） was designed and its uptake by endothelial cells was assessed both in vitro and in vivo to evaluate the angiogenic profile of lung cancer.Methods USPIO were coated with-NH3＋ and conjugated with RGD peptides.Prussian blue staining was performed to evaluate the specific uptake of RGD-USPIO by human umbilical vein endothelial cells （HUVECs）.Targeted uptake and subcellular localization of RGD-USPIO in HUVECs were confirmed by transmission electron microscopy （TEM）.The ability of RGD-USPIO to noninvasively assess αvβ3 integrin positive vessels in lung adenocarcinoma A549 tumor xenografts was evaluated with a 4.7T MR scanner.Immunohistochemistry was used to detect αvβ3 integrin expression and vessel distribution in A549 tumor xenografts.Results HUVECs internalized RGD-USPIO significantly more than plain USPIO.The uptake of RGD-USPIO by HUVECs could be competitively inhibited by addition of free RGD.A significant decrease in T2 signal intensity （SI） was observed at the periphery of A549 tumor xenografts at 30 minutes （P 〈0.05） and 2 hours （P 〈0.01） after RGD-USPIO was injected via the tail vein.Angiogenic blood vessels were mainly distributed in the periphery of tumor xenografts with positive αvβ3 integrin expression.Conclusions RGD-USPIO could specifically label αvβ3 integrin and be taken up by HUVECs.This molecular MR imaging contrast agent can specifically evaluate the angiogenic profile of lung cancer using a 4.7T MR scanner.
基金the Open Foundation of National Defense Key Discipline Laboratory of Light Alloy Processing Science and Technology (Grant No.gf201401001)the National Natural Science Foundation of China (Grant No.51171154)
文摘A composite coating containing hexagonal boron nitride（hBN） particles and titanium oxide（TiO_2） was formed on the surface of Ti-6Al-4V alloy via micro-arc oxidation（MAO）. The effect of quantity of the hBN-particles added into electrolyte on microstructure, composition, and wear behavior of the resulting composite coatings was investigated. Microstructure, phase composition, and tribological behavior of the resulting MAO coatings were evaluated via scanning electron microscopy, X-ray diffraction, and ball-on-disc abrasive tests. The results reveal that the TiO_2/hBN composite coating consisting of rutile TiO_2, anatase TiO_2, and an hBN phase was less porous than particle-free coating. Furthermore, the presence of hBN particles in the MAO coating produced an improved anti-friction property. The composite coating produced in the electrolyte containing 2 g/L of hBN particles exhibited the best wear resistance.The outer loose layer of the MAO coatings was removed by a mechanical polishing process, which led to a significant improvement in the wear resistance and anti-friction properties of the MAO coatings and highlighted an essential lubricating role of hBN particles in the composite coatings. However, wear mechanism of the MAO coatings was not relevant to the presence of hBN particles, where fatigue wear dominated the anti-fraction properties of the MAO coatings with and without hBN particles.
文摘The electrochemical behavior of the 3-(4-N-pyridine-2-yl benzene sulfonamide azo)-1-nitroso naphthol reagent and its complex with Co(II)has been studied at glassy carbon disk electrode in different supporting electrolyte at concentration 1 mol and scan rate(100 mV/s).3-(4-N-pyridine-2-yl benzene sulfonamide azo)-1-nitroso naphthol was used for enhance the properties of nano cobalt oxide by ligand exchange reaction on nanoparticles.
基金supported by the National Key R&D Program of China(grant No.2022YFB1902503)the National Natural Science Foundation of China(grant Nos.12027813,12105101)+1 种基金the Fund of Science and Technology on Reactor System Design Technology Laboratory(grant No.KFKT-05-FW-HT-20220010)the Fundamental Research Funds for the Central Universities.
文摘The coupled CFD-DEM simulations are widely recognized as a powerful approach for analyzing various particle-fluid systems.In lead-bismuth nuclear reactors,the liquid lead-bismuth eutectic(LBE)alloy is employed as the coolant,and the solid-phase oxygen control is a key technique for corrosion mitigation.In this work,diffusive smoothing CFD-DEM simulations are performed to investigate the particle-scale mass transfer behaviors of LBE solid-phase oxygen control loops.The dissolution of the lead oxide particle within the mass exchanger serves as the source term of the mass transfer processes.In the current model,the fluid flow,particle motion,particle-fluid interaction forces,and the mass transfer of oxygen concentration in LBE are incorporated in the governing equations.When the CFD cell size is smaller than the particle diameter,the diffusive smoothing method is proposed to calculate the void fraction field.Compared with the experimental results,the numerical simulations give a satisfactory prediction of the flow dynamics and particle-scale mass transfer.In the small-sized experiment,the total dissolution rate is about 0.0031 g/h at 380 C,and it is notably lower than the oxygen consumption in a full-scale megawatt-level lead-bismuth reactor.A large-scale mass exchanger is designed,and the numerical simulations indicate that the oxygen control system achieves a dissolution rate ranging from 5.28 to 23.74 g/h at temperatures of 380-420℃.It is sufficient to meet the expected oxygen consumption of 4.5 g/h in the nuclear reactor.The diffusive smoothing CFD-DEM approach provides a robust tool for the design and optimization of oxygen control loops of advanced lead-bismuth fast nuclear reactors.
基金National Engineering Research Center of UHV Technology and Novel Electrical Equipment Basis,Grant/Award Number:NERCUHV-2023-KF-02。
文摘In this study,the functional gradient materials(FGMs)were the first attempt to homogenise the electric field distribution in the cable accessory,where zinc oxide particles(ZnO_(k))were filled into ethylene propylene diene monomer with the composi-tionally gradient distribution using laminating and hot-pressing methods.The constructed FGMs with significantly improved non-linear conductivity can avoid the electric field distortion in cable accessories.The results show that the configuration of compositionally gradient structured fillers can significantly improve the electrical conductivity of FGMs compared to the homogeneous distribution.Additionally,compositionally gradient structures of ZnOk fillers can also improve the thermal conductivity of FGM composites,which facilitates the heat dissipation of dielectric and reduces the probability of electrothermal coupling breakdown.The mechanical properties of the composites are deeply affected by the filler's content and configuration,both improved tear elongation and tensile strength can be achieved at an optimal content and gradient structure of ZnOk fillers.Finally,the simulation analysis results show that FGM composites can homogenise the electric field more efficiently in comparison with homogeneous composites.This work demonstrates that compositionally gradient structures can improve the utilisation of functional fillers and develop the FGM composites for high-voltage direct current cable accessory applications.
基金funded by the German Research Foundation DFG under grants WI1602/16-1 and WI1602/16-2.
文摘Wide-angle light scattering(WALS)was used for in situ measurements of droplet and nanoparticle size distributions during the synthesis of titania and iron oxide particles from liquid precursor solutions in the standardized SpraySyn burner for spray flame synthesis.Titania was synthesized from titanium tetraisopropoxide(TTIP)and iron oxide from iron(II)nitrate nonahydrate(INN)using ethanol(EtOH)as solvent.Scattering images were taken at heights up to 120 mm above the burner surface and classified into droplet and particle scattering.Droplet size distributions were derived from a sequential analysis of scattering data containing the oscillating Mie pattern,the lognormal size distribution parameters for spherical and fractal particle fractions from a multivariate approach on averaged particle scattering data.The results show that the precursor addition leads to altered evaporation behavior and even droplet disruption probably induced by puffing or micro-explosions compared to pure EtOH.In the case of TTIP(a hygroscopic alkoxide),the synthesis of a large fraction of spheres was observed,while the nitrate INN leads to the formation of mostly fractal aggregates.
基金supported by the Natural Science Foundation of Shandong Province (ZR2009AM016)
文摘The effect of non-Gaussian colored noise(NGN),mainly its departure q from the Gaussian noise,on the optimal ISRO of CO oxidation on nanometer-sized Pd particles was studied.It was found that the ISRO in the absence of external noise can still be enhanced when the NGN is applied.Specifically,the ISRO varies with changing q and becomes more regular at an appropriate q value,and when q is optimal,the ISRO becomes the most regular.Because the departure q from the Gaussian noise determines the probability distribution function and hence may denote the types of noise,this result shows that different types of external noise can enhance the ISRO of CO oxidation,and non-Gaussian noise may enhance the ISRO more greatly than the Gaussian noise.Therefore,non-Gaussian noise could play more effective roles in the catalytic process of CO oxidation on nanometer-sized Pd particles.
基金This work was supported by grants from the Major State Basic Research Program （No. 2010CB945500, No. 2009CB941100 and No. 2007CB947902）, the National Natural Science Foundation of China （No. 90919002 and No. 30870805）, Shanghai Committee of Science and Technology （No. 08dj140053 and No. 2007Y39） and Postgraduate＇s Research Program of Fudan University （2010）.
文摘Background Previously we had successfully tracked adult human neural stem cells （NSCs） labeled with superparamagnetic iron oxide particles （SPIOs） in host human brain after transplantation in vivo non-invasively by magnetic resonance imaging （MRI）. However, the function of the transplanted NSCs could not be evaluated by the method. In the study, we applied manganese-enhanced MRI （ME-MRI） to detect NSCs function after implantation in brain of rats with traumatic brain injury （TBI） in vivo. Methods Totally 40 TBI rats were randomly divided into 4 groups with 10 rats in each group. In group 1, the TBI rats did not receive NSCs transplantation. MnCI2＂4H20 was intravenously injected, hyperosmolar mannitol was delivered to disrupt rightside blood brain barrier, and its contralateral forepaw was electrically stimulated. In group 2, the TBI rats received NSCs （labeled with SPIO） transplantation, and the ME-MRI procedure was same to group 1. In group 3, the TBI rats received NSCs （labeled with SPIO） transplantation, and the ME-MRI procedure was same to group 1, but diltiazem was introduced during the electrical stimulation period. In group 4, the TBI rats received phosphate buffered saline （PBS） injection, and the ME-MRI procedure was same to group 1. Results Hyperintense signals were detected by ME-MRI in the cortex areas associated with somatosensory in TBI rats of group 2. These signals, which could not be induced in TBI rats of groups 1 and 4, disappeared when diltiazem was introduced in TBI rats of group 3. Conclusion In this initial study, we mapped implanted NSCs activity and its functional participation within local brain area in TBI rats by ME-MRI technique, paving the way for further pre-clinical research.
