In this study,a functionalized covalent-organic framework(COF)was first synthesized using porphyrin as the fabrication unit and showed an edge-curled,petal-like and well-ordered structure.The synthesized COF was then ...In this study,a functionalized covalent-organic framework(COF)was first synthesized using porphyrin as the fabrication unit and showed an edge-curled,petal-like and well-ordered structure.The synthesized COF was then introduced to prepare porous organic polymer monolithic materials(POPMs).Two composite POPM/COF monolithic materials with rod shapes,referred to as sorbent A and sorbent B,were prepared in stainless steel tubes using different monomers.Sorbents A and B exhibited relatively uniform porous structures and enhanced specific surface areas of 153.14 m;/g and 80.01 m;/g,respectively.The prepared composite monoliths were used as in-tube solid-phase extraction(SPE)sorbents combined with HPLC for the on-line extraction and quantitative analytical systems.Indole alkaloids(from Catharanthus roseus G.Don and Uncaria rhynchophylla(Miq.)Miq.Ex Havil.)contained in mouse plasma were extracted and quantitatively analyzed using the online system.The two composite multifunctional monoliths showed excellent clean-up ability for complex biological matrices,as well as superior selectivity for target indole alkaloids.Method validation showed that the RSD values of the repeatability(n=6)were≤3.46%,and the accuracy expressed by the spiked recoveries was in the ranges of 99.38%-100.91%and 96.39%-103.50%for vinca alkaloids and Uncaria alkaloids,respectively.Furthermore,sorbents A and B exhibited strong reusability,with RSD values≤5.32%,which were based on the peak area of the corresponding alkaloids with more than 100 injections.These results indicate that the composite POPM/COF rod-shaped monoliths are promising media as SPE sorbents for extracting trace compounds in complex biological samples.展开更多
Owing to the high temperatures and prolonged durations typically required for conventional sintering(CS),various forms of electric field-assisted sintering,particularly flash sintering(FS),have garnered significant at...Owing to the high temperatures and prolonged durations typically required for conventional sintering(CS),various forms of electric field-assisted sintering,particularly flash sintering(FS),have garnered significant attention for their potential to improve sintering efficiency.FS involves passing an electric current through a sample to generate Joule heating,enabling rapid material densification in a very short time.However,the application of FS to large samples is hindered by several detrimental issues,including the formation of large cracks caused by extremely rapid heating rates(~10°C/min)and the nonuniform distribution of current and temperature.This study introduces a novel method called electric field-controlled sintering(ECS),in which the current passing directly through the sample is regulated to achieve a slower heating rate of 100–300°C/min(although still significantly faster than that of CS).This approach facilitates the production of large cylindrical samples with diameters of up to 30 mm,which exhibit excellent mechanical properties and are free from observable cracks.The materials used in this study possess electrical conductivities exceeding 106 S/m,ensuring uniform current and temperature distributions.The ECS technique can be used for sintering various materials,including MAX phases,cemented carbides,ultrahigh-temperature ceramics,and refractory metals.Additionally,the athermal effect in the ECS process was investigated,which refers to the changes in sintering behavior and material properties induced by the electric current itself rather than by Joule heating.Consequently,the proposed ECS method is expected to address the limitations of FS,which hinders its industrial application,while it also provides a means to study the athermal effects on sintering behavior and material properties.展开更多
基金supported by the Natural Science Foundation of Hebei Province (Grant No.: B2020201002)the National Natural Science Foundation of China (Grant Nos.: 21974034 and 21505030)the Interdisciplinary Research Project of Natural Science of Hebei University (Grant No.: DXK201912)
文摘In this study,a functionalized covalent-organic framework(COF)was first synthesized using porphyrin as the fabrication unit and showed an edge-curled,petal-like and well-ordered structure.The synthesized COF was then introduced to prepare porous organic polymer monolithic materials(POPMs).Two composite POPM/COF monolithic materials with rod shapes,referred to as sorbent A and sorbent B,were prepared in stainless steel tubes using different monomers.Sorbents A and B exhibited relatively uniform porous structures and enhanced specific surface areas of 153.14 m;/g and 80.01 m;/g,respectively.The prepared composite monoliths were used as in-tube solid-phase extraction(SPE)sorbents combined with HPLC for the on-line extraction and quantitative analytical systems.Indole alkaloids(from Catharanthus roseus G.Don and Uncaria rhynchophylla(Miq.)Miq.Ex Havil.)contained in mouse plasma were extracted and quantitatively analyzed using the online system.The two composite multifunctional monoliths showed excellent clean-up ability for complex biological matrices,as well as superior selectivity for target indole alkaloids.Method validation showed that the RSD values of the repeatability(n=6)were≤3.46%,and the accuracy expressed by the spiked recoveries was in the ranges of 99.38%-100.91%and 96.39%-103.50%for vinca alkaloids and Uncaria alkaloids,respectively.Furthermore,sorbents A and B exhibited strong reusability,with RSD values≤5.32%,which were based on the peak area of the corresponding alkaloids with more than 100 injections.These results indicate that the composite POPM/COF rod-shaped monoliths are promising media as SPE sorbents for extracting trace compounds in complex biological samples.
基金supported by the National Natural Science Foundation of China(Nos.52372064 and 52472074)the China Postdoctoral Science Foundation(Nos.2023M741880 and GZC20231204).
文摘Owing to the high temperatures and prolonged durations typically required for conventional sintering(CS),various forms of electric field-assisted sintering,particularly flash sintering(FS),have garnered significant attention for their potential to improve sintering efficiency.FS involves passing an electric current through a sample to generate Joule heating,enabling rapid material densification in a very short time.However,the application of FS to large samples is hindered by several detrimental issues,including the formation of large cracks caused by extremely rapid heating rates(~10°C/min)and the nonuniform distribution of current and temperature.This study introduces a novel method called electric field-controlled sintering(ECS),in which the current passing directly through the sample is regulated to achieve a slower heating rate of 100–300°C/min(although still significantly faster than that of CS).This approach facilitates the production of large cylindrical samples with diameters of up to 30 mm,which exhibit excellent mechanical properties and are free from observable cracks.The materials used in this study possess electrical conductivities exceeding 106 S/m,ensuring uniform current and temperature distributions.The ECS technique can be used for sintering various materials,including MAX phases,cemented carbides,ultrahigh-temperature ceramics,and refractory metals.Additionally,the athermal effect in the ECS process was investigated,which refers to the changes in sintering behavior and material properties induced by the electric current itself rather than by Joule heating.Consequently,the proposed ECS method is expected to address the limitations of FS,which hinders its industrial application,while it also provides a means to study the athermal effects on sintering behavior and material properties.
