There is an increasing interest in biodegradable materials,such as magnesium,for orthopaedic implants.This is driven by their potential to address challenges like stress shielding and the need for secondary removal su...There is an increasing interest in biodegradable materials,such as magnesium,for orthopaedic implants.This is driven by their potential to address challenges like stress shielding and the need for secondary removal surgery.In this study,biodegradable magnesium alloys were produced using the Vacuum Induction Casting technique.The impact of micro-alloying Zn and Ca in Mg-xZn-0.2Ca(x=0.1,0.2,0.3,and 0.4 wt%)alloys on corrosion resistance,cytocompatibility,and early-stage inflammatory response was investigated.XRD and SEM-EDS analysis confirmed the presence of Ca_(2)Mg_(6)Zn_(3)secondary phases in all alloys.The Mg-0.3Zn-0.2Ca alloy exhibited the lowest corrosion rate and an elastic modulus of 36.8 GPa,resembling that of natural bone.Electrochemical measurements indicated a correlation between grain size and secondary phase volume fraction in explaining corrosion behaviour.In vitro degradation in simulated body fluid(SBF)for 21 days showed hydroxyapatite formation on alloy surfaces,aligning with electrochemical studies.In vitro cytotoxicity tests demonstrated the cytocompatibility of all alloys,with Mg-0.3Zn-0.2Ca having the highest cell viability over a 6-day cell culture.Investigation into the inflammatory response with RAW-Blue macrophages revealed the anti-inflammatory properties of Mg-0.3Zn-0.2Ca alloys.Micro-alloying with 0.3 wt%Zn and 0.2 wt%Ca enhanced mechanical properties,corrosion resistance,cytocompatibility,and immunomodulatory properties.This positions the Mg-0.3Zn-0.2Ca alloy as a promising biodegradable implant for bone fixation applications.展开更多
A fully dense carbon nanotubes (CNTs) reinforced AlSi matrix composite with the multiscale nacre-like architecture was designed and successfully realized by flake powder metallurgy followed by cold spraying (CS). The ...A fully dense carbon nanotubes (CNTs) reinforced AlSi matrix composite with the multiscale nacre-like architecture was designed and successfully realized by flake powder metallurgy followed by cold spraying (CS). The nanolaminated and ultrafine-grained structure initially created in the CNT/AlSi flaky powder was perfectly conserved, due to the typical ‘cold’ feature of CS. As discussed based on finite element analysis and single splat observation, self-alignment behavior of the flaky powders during impact also allowed the formation of the microlaminated structure. Hence, the scalable CS technique opens a new avenue for bioinspired material design and fabrication with complex shape.展开更多
Ciprofloxacin (CFX) was loaded on Bana clay (Cameroon) and CFX loaded-clays have been evaluated as drug delivery system. Raw clays and CFX loaded compounds have been characterized by some physico-chemicals methods. &l...Ciprofloxacin (CFX) was loaded on Bana clay (Cameroon) and CFX loaded-clays have been evaluated as drug delivery system. Raw clays and CFX loaded compounds have been characterized by some physico-chemicals methods. <i>In vitro</i> release studies have been done in gastric and phosphate buffer experimental mediums;bacteriological studies have been made up on <i>Escherichia coli</i> and <i>Staphylococcus aureus</i>. X-ray diffractometry patterns of loaded compounds show a basal spacing increasing due to CFX intercalation. On Fourier-Transformed Infrared spectrometry spectra, appearance of CFX characteristic bands and shifting of certain bands already presents on clay confirmed CFX intercalation. After 96 h of CFX released from release mediums, prolonged and continue profiles have been observed. Diffusion tests displayed an inhibition radius of ~2 cm on gelose seeded with <i>Escherichia coli</i> and <i>Staphylococcus aureus</i> due to CFX. The overall results show a modified release of ciprofloxacin with an effective antibacterial activity, giving the way for a new ciprofloxacin drug delivery system using Bana clay as carrier.展开更多
Porous SiO2 has been chemically modified with functional ortho-, meta- or para-nitrophenyl moieties using the heterogeneous route. This synthetic route involved the reaction of carbaldehyde derivatives with 3-aminopro...Porous SiO2 has been chemically modified with functional ortho-, meta- or para-nitrophenyl moieties using the heterogeneous route. This synthetic route involved the reaction of carbaldehyde derivatives with 3-aminopropyl trimethoxysilane prior to immobilization on the support. The new modified surfaces have been characterized by elemental analysis, FT-IR, 13C NMR of the solid state, nitrogen adsorption-desorption isotherm, BET surface area, B.J.H. Pore sizes, thermogravimetry curves (TGA) and scanning electron microscope (SEM). The new materials exhibit good chemical and thermal stability. These products were employed as a Cu(II) adsorbent from aqueous solutions at room temperature using the batch technique. Flame atomic absorption spectrometry was used to determine the Cu(II) concentration in the filtrate after the adsorption process. The results indicate that under the optimum conditions, the maximum adsorption value for Cu(II) was 20.0 mg Cu(II) g-1 modified silica, whereas the adsorption capacity of the unmodified silica was only 1.0 mg Cu(II) g-1 silica. On the basis of these results, it can be concluded that it is possible to modify chemically SiO2 with functional groups and use it as adsorbents for metals in aqueous media.展开更多
Elastomer blends,among which natural rubber(NR)and butadiene rubber(BR),are involved in many components of the automotive/tire industry.A comprehensive understanding of their mechanical behavior requires,among other f...Elastomer blends,among which natural rubber(NR)and butadiene rubber(BR),are involved in many components of the automotive/tire industry.A comprehensive understanding of their mechanical behavior requires,among other features,a detailed description of the crosslink density in these mixtures.In the case of vulcanized immiscible blends,the distribution of the cross-link density within each of the NR-and BR-rich domains is key information,but difficult to determine using the conventional approaches used for one-component crosslinked elastomers.In this study,the vulcanization within NR/BR blends is investigated using a robust^(1)H double-quantum(DQ)MAS recoupling experiment,BaBa-xy16.Two kinds of cross-linked NR/BR blends were considered with two different microstructures for the BR component.The bulk organization of the resulting blends was first probed by analyzing the^(1)H spin-lattice relaxation behavior.In a second step,BaBa-xy16 was used to investigate,in a selective way,the cross-link heterogeneities within NR/BR blends.In particular,for immiscible NR/BR mixtures,the distribution of the cross-link density between both phases was compared and the observed differences were discussed.展开更多
Dexamethasone-loaded silicone matrices offer an interesting potential as innovative drug delivery systems,e.g.for the treatment of inner ear diseases or for pacemakers.Generally,very long drug release periods are targ...Dexamethasone-loaded silicone matrices offer an interesting potential as innovative drug delivery systems,e.g.for the treatment of inner ear diseases or for pacemakers.Generally,very long drug release periods are targeted:several years/decades.This renders the development and optimization of novel drug products cumbersome:experimental feedback on the impact of the device design is obtained very slowly.A better understanding of the underlying mass transport mechanisms can help facilitating research in this field.A variety of silicone films were prepared in this study,loaded with amorphous or crystalline dexamethasone.Different polymorphic drug forms were investigated,the film thickness was altered and the drug optionally partially/completely exchanged by much more water-soluble dexamethasone‘phosphate’.Drug release studies in artificial perilymph,scanning electron microscopy,optical microscopy,differential scanning calorimetry,X-ray diffraction and Raman imaging were used to elucidate the physical states of the drugs and polymer,and of the systems’structure as well as dynamic changes thereof upon exposure to the release medium.Dexamethasone particles were initially homogeneously distributed throughout the systems.The hydrophobicity of the matrix former very much limits the amounts of water penetrating into the system,resulting in only partial drug dissolution.The mobile drug molecules diffuse out into the surrounding environment,due to concentration gradients.Interestingly,Raman imaging revealed that even very thin silicone layers(<20µm)can effectively trap the drug for prolonged periods of time.The physical state of the drug(amorphous,crystalline)did not affect the resulting drug release kinetics to a noteworthy extent.展开更多
Recycled oceanic crust （ROC） has long been suggested to be a candidate introducing en- riched geochemical signatures into the mantle source of intraplate basalts. The different parts of oceanic crust are characteriz...Recycled oceanic crust （ROC） has long been suggested to be a candidate introducing en- riched geochemical signatures into the mantle source of intraplate basalts. The different parts of oceanic crust are characterized by variable oxygen isotope compositions （δ^18O=3.7‰ to 13.6‰）. To trace the sig- natures of ROC in the mantle source of intraplate basalts, we measured the δ^18O values of clinopyroxene （cpx） phenocrysts in the Cenozoic basalts from the Shuangliao volcanic field, NE China using secondary ion mass spectrometer （SIMS）. The δ^18O values of the Shuangliao cpx phenocrysts in four basalts ranging from 4.10‰ to 6.73‰ （with average values 5.93‰±0.36‰, 5.95‰±0.30‰0, 5.58‰±=0.66‰e, and 4.55‰±= 0.38‰, respectively） apparently exceed those of normal mantle-derived cpx （5.6‰±0.2‰） and fall in the typical oxygen isotope range of altered oceanic crust. The δ^18O values display the negative correlations with the Eu, Sr anomalies of whole rocks and erupted ages, demonstrating that （1） the ROC is the main enriched component in the mantle source of the Shuangliao basalts and （2） the contributions of ROC var- ied with time. The basalt with the lowest δ^18O value is characterized by a significant K positive anomaly, highest H2O/Ce and Ba/Th ratios, suggesting that the mantle source of basalts with low δ^18O can also in- clude a water-rich sediment component that may be the trigger for partial melting. Considering the continuous subduction of the Pacific slab, the temporal heterogeneity of the source components is likely to be caused by the Pacific slab subduction.展开更多
Water has become an effective means to trace the mantle source of basaltic magmas recently. To investigate the source of the potassium-rich component in the Xiaogulihe ultrapotassic volcanic rocks of NE China, we meas...Water has become an effective means to trace the mantle source of basaltic magmas recently. To investigate the source of the potassium-rich component in the Xiaogulihe ultrapotassic volcanic rocks of NE China, we measured the water content of clinopyroxene （cpx） phenocrysts by Fourier transform infrared spectrometry and calculated the H2O content of the equilibrated melts according to the partition coefficients of H2O between cpx phenocrysts and basaltic melts. The estimated H2O content of the ＂primary＂ magmas is low （0.36 wt%-0.50 wt%）, within the range of mid-ocean ridge basalts and ocean island basalts, while it is obviously lower than that of backarc basin basalts and island arc basalts. The calculated H20/Ce ratio of the ＂primary＂ magmas is about 15, which might be similar to that of the dehydrated sediments （〈100）, but observably lower than that of the normal depleted mantle （DMM, H2O/Ce = 150-210）. The low water content and especially low H2O/Ce ratio of the ＂primary＂ magmas demonstrate that the K-rich component of these ultrapotassic volcanic rocks seems unlikely tooriginate from K-bearing hydrous minerals （such as phlogopite） in metasomatic subcontinental lithospheric mantle. Combined with the low 206pb/204pb ratios, moderately high 87Sr/86Sr ratios of the bulk rocks and the high δ18O values of olivine phenocrysts, we suggest that the K-rich component in the mantle source of the Xiaogulihe ultrapotassic volcanic rocks may come from ancient continental-derived sediments which dehydrated significantly during subduction （e.g., dry K-hollandite）.展开更多
基金funded by European Union’s Horizon 2020 Research and Innovation program and‘Magnesium based Nano Composites for Orthopedic Applications’MAGNACOM,project under the aegis of Programme for Early-Stage Researchers(PEARL,I-Site ULNE under the Marie Sklodowska-Curie grant agreement)supported by University of Lille(France)and Hauts-de-France region.
文摘There is an increasing interest in biodegradable materials,such as magnesium,for orthopaedic implants.This is driven by their potential to address challenges like stress shielding and the need for secondary removal surgery.In this study,biodegradable magnesium alloys were produced using the Vacuum Induction Casting technique.The impact of micro-alloying Zn and Ca in Mg-xZn-0.2Ca(x=0.1,0.2,0.3,and 0.4 wt%)alloys on corrosion resistance,cytocompatibility,and early-stage inflammatory response was investigated.XRD and SEM-EDS analysis confirmed the presence of Ca_(2)Mg_(6)Zn_(3)secondary phases in all alloys.The Mg-0.3Zn-0.2Ca alloy exhibited the lowest corrosion rate and an elastic modulus of 36.8 GPa,resembling that of natural bone.Electrochemical measurements indicated a correlation between grain size and secondary phase volume fraction in explaining corrosion behaviour.In vitro degradation in simulated body fluid(SBF)for 21 days showed hydroxyapatite formation on alloy surfaces,aligning with electrochemical studies.In vitro cytotoxicity tests demonstrated the cytocompatibility of all alloys,with Mg-0.3Zn-0.2Ca having the highest cell viability over a 6-day cell culture.Investigation into the inflammatory response with RAW-Blue macrophages revealed the anti-inflammatory properties of Mg-0.3Zn-0.2Ca alloys.Micro-alloying with 0.3 wt%Zn and 0.2 wt%Ca enhanced mechanical properties,corrosion resistance,cytocompatibility,and immunomodulatory properties.This positions the Mg-0.3Zn-0.2Ca alloy as a promising biodegradable implant for bone fixation applications.
基金financial support from China Scholarship Council for his Ph.D. projectThe TEM facility in Lille, France, is supported by the Conseil Regional du Nord-Pas de Calais and the European Regional Development Fund
文摘A fully dense carbon nanotubes (CNTs) reinforced AlSi matrix composite with the multiscale nacre-like architecture was designed and successfully realized by flake powder metallurgy followed by cold spraying (CS). The nanolaminated and ultrafine-grained structure initially created in the CNT/AlSi flaky powder was perfectly conserved, due to the typical ‘cold’ feature of CS. As discussed based on finite element analysis and single splat observation, self-alignment behavior of the flaky powders during impact also allowed the formation of the microlaminated structure. Hence, the scalable CS technique opens a new avenue for bioinspired material design and fabrication with complex shape.
文摘Ciprofloxacin (CFX) was loaded on Bana clay (Cameroon) and CFX loaded-clays have been evaluated as drug delivery system. Raw clays and CFX loaded compounds have been characterized by some physico-chemicals methods. <i>In vitro</i> release studies have been done in gastric and phosphate buffer experimental mediums;bacteriological studies have been made up on <i>Escherichia coli</i> and <i>Staphylococcus aureus</i>. X-ray diffractometry patterns of loaded compounds show a basal spacing increasing due to CFX intercalation. On Fourier-Transformed Infrared spectrometry spectra, appearance of CFX characteristic bands and shifting of certain bands already presents on clay confirmed CFX intercalation. After 96 h of CFX released from release mediums, prolonged and continue profiles have been observed. Diffusion tests displayed an inhibition radius of ~2 cm on gelose seeded with <i>Escherichia coli</i> and <i>Staphylococcus aureus</i> due to CFX. The overall results show a modified release of ciprofloxacin with an effective antibacterial activity, giving the way for a new ciprofloxacin drug delivery system using Bana clay as carrier.
文摘Porous SiO2 has been chemically modified with functional ortho-, meta- or para-nitrophenyl moieties using the heterogeneous route. This synthetic route involved the reaction of carbaldehyde derivatives with 3-aminopropyl trimethoxysilane prior to immobilization on the support. The new modified surfaces have been characterized by elemental analysis, FT-IR, 13C NMR of the solid state, nitrogen adsorption-desorption isotherm, BET surface area, B.J.H. Pore sizes, thermogravimetry curves (TGA) and scanning electron microscope (SEM). The new materials exhibit good chemical and thermal stability. These products were employed as a Cu(II) adsorbent from aqueous solutions at room temperature using the batch technique. Flame atomic absorption spectrometry was used to determine the Cu(II) concentration in the filtrate after the adsorption process. The results indicate that under the optimum conditions, the maximum adsorption value for Cu(II) was 20.0 mg Cu(II) g-1 modified silica, whereas the adsorption capacity of the unmodified silica was only 1.0 mg Cu(II) g-1 silica. On the basis of these results, it can be concluded that it is possible to modify chemically SiO2 with functional groups and use it as adsorbents for metals in aqueous media.
基金financial support from the French National Research Agency(ANR)[grant number ANR-22-CE06-0031]。
文摘Elastomer blends,among which natural rubber(NR)and butadiene rubber(BR),are involved in many components of the automotive/tire industry.A comprehensive understanding of their mechanical behavior requires,among other features,a detailed description of the crosslink density in these mixtures.In the case of vulcanized immiscible blends,the distribution of the cross-link density within each of the NR-and BR-rich domains is key information,but difficult to determine using the conventional approaches used for one-component crosslinked elastomers.In this study,the vulcanization within NR/BR blends is investigated using a robust^(1)H double-quantum(DQ)MAS recoupling experiment,BaBa-xy16.Two kinds of cross-linked NR/BR blends were considered with two different microstructures for the BR component.The bulk organization of the resulting blends was first probed by analyzing the^(1)H spin-lattice relaxation behavior.In a second step,BaBa-xy16 was used to investigate,in a selective way,the cross-link heterogeneities within NR/BR blends.In particular,for immiscible NR/BR mixtures,the distribution of the cross-link density between both phases was compared and the observed differences were discussed.
基金funding from the French National Research Agency(ANR-15-CE19-0014-01/03)the Interreg 2 Seas programme 2014-2020 co-funded by the European Regional Development Fund under subsidy contract‘Site Drug 2S07-033’.
文摘Dexamethasone-loaded silicone matrices offer an interesting potential as innovative drug delivery systems,e.g.for the treatment of inner ear diseases or for pacemakers.Generally,very long drug release periods are targeted:several years/decades.This renders the development and optimization of novel drug products cumbersome:experimental feedback on the impact of the device design is obtained very slowly.A better understanding of the underlying mass transport mechanisms can help facilitating research in this field.A variety of silicone films were prepared in this study,loaded with amorphous or crystalline dexamethasone.Different polymorphic drug forms were investigated,the film thickness was altered and the drug optionally partially/completely exchanged by much more water-soluble dexamethasone‘phosphate’.Drug release studies in artificial perilymph,scanning electron microscopy,optical microscopy,differential scanning calorimetry,X-ray diffraction and Raman imaging were used to elucidate the physical states of the drugs and polymer,and of the systems’structure as well as dynamic changes thereof upon exposure to the release medium.Dexamethasone particles were initially homogeneously distributed throughout the systems.The hydrophobicity of the matrix former very much limits the amounts of water penetrating into the system,resulting in only partial drug dissolution.The mobile drug molecules diffuse out into the surrounding environment,due to concentration gradients.Interestingly,Raman imaging revealed that even very thin silicone layers(<20µm)can effectively trap the drug for prolonged periods of time.The physical state of the drug(amorphous,crystalline)did not affect the resulting drug release kinetics to a noteworthy extent.
基金supported by the National Natural Science Foundation of China(Nos.41225005 and 41173047)
文摘Recycled oceanic crust （ROC） has long been suggested to be a candidate introducing en- riched geochemical signatures into the mantle source of intraplate basalts. The different parts of oceanic crust are characterized by variable oxygen isotope compositions （δ^18O=3.7‰ to 13.6‰）. To trace the sig- natures of ROC in the mantle source of intraplate basalts, we measured the δ^18O values of clinopyroxene （cpx） phenocrysts in the Cenozoic basalts from the Shuangliao volcanic field, NE China using secondary ion mass spectrometer （SIMS）. The δ^18O values of the Shuangliao cpx phenocrysts in four basalts ranging from 4.10‰ to 6.73‰ （with average values 5.93‰±0.36‰, 5.95‰±0.30‰0, 5.58‰±=0.66‰e, and 4.55‰±= 0.38‰, respectively） apparently exceed those of normal mantle-derived cpx （5.6‰±0.2‰） and fall in the typical oxygen isotope range of altered oceanic crust. The δ^18O values display the negative correlations with the Eu, Sr anomalies of whole rocks and erupted ages, demonstrating that （1） the ROC is the main enriched component in the mantle source of the Shuangliao basalts and （2） the contributions of ROC var- ied with time. The basalt with the lowest δ^18O value is characterized by a significant K positive anomaly, highest H2O/Ce and Ba/Th ratios, suggesting that the mantle source of basalts with low δ^18O can also in- clude a water-rich sediment component that may be the trigger for partial melting. Considering the continuous subduction of the Pacific slab, the temporal heterogeneity of the source components is likely to be caused by the Pacific slab subduction.
基金supported by the National Natural Science Foundation of China(41225005)the Research Fund for the Doctoral Program of Higher Education of China(RFDP20113402130001)
文摘Water has become an effective means to trace the mantle source of basaltic magmas recently. To investigate the source of the potassium-rich component in the Xiaogulihe ultrapotassic volcanic rocks of NE China, we measured the water content of clinopyroxene （cpx） phenocrysts by Fourier transform infrared spectrometry and calculated the H2O content of the equilibrated melts according to the partition coefficients of H2O between cpx phenocrysts and basaltic melts. The estimated H2O content of the ＂primary＂ magmas is low （0.36 wt%-0.50 wt%）, within the range of mid-ocean ridge basalts and ocean island basalts, while it is obviously lower than that of backarc basin basalts and island arc basalts. The calculated H20/Ce ratio of the ＂primary＂ magmas is about 15, which might be similar to that of the dehydrated sediments （〈100）, but observably lower than that of the normal depleted mantle （DMM, H2O/Ce = 150-210）. The low water content and especially low H2O/Ce ratio of the ＂primary＂ magmas demonstrate that the K-rich component of these ultrapotassic volcanic rocks seems unlikely tooriginate from K-bearing hydrous minerals （such as phlogopite） in metasomatic subcontinental lithospheric mantle. Combined with the low 206pb/204pb ratios, moderately high 87Sr/86Sr ratios of the bulk rocks and the high δ18O values of olivine phenocrysts, we suggest that the K-rich component in the mantle source of the Xiaogulihe ultrapotassic volcanic rocks may come from ancient continental-derived sediments which dehydrated significantly during subduction （e.g., dry K-hollandite）.
