In the context of convection-heating-based in situ oil shale retorting,fractures serve as primary pathways for fluid migration and product extraction.This study investigates the permeability and microstructural evolut...In the context of convection-heating-based in situ oil shale retorting,fractures serve as primary pathways for fluid migration and product extraction.This study investigates the permeability and microstructural evolution of oil shale during water vapor injection in single-fracture and no-fracture scenarios.Three types of oil shale are investigated:intact oil shale,oil shale with a single straight crack,and oil shale with a single hydraulic crack.With increasing water vapor temperature,the permeabilities of the intact oil shale and oil shale with a fractured crack exhibit a trend of initial increase,followed by a decrease,and then a subsequent increase.However,the permeability of oil shale with a single straight crack consistently increases and exceeds that of oil shale with a fractured crack.The temperaturedependent permeability changes in fractured oil shale-a slight decrease in fracture cracks and a gradual increase in straight cracks-mainly occur in the range of 300℃-350℃.The permeability of oil shale with a straight crack is approximately three times that of oil shale with a fractured crack.This is attributed to the retention of viscous asphaltene and the frictional resistance caused by the rough fracture structure.For the oil shale with a single crack,the crack permeability has a dominant influence on the overall permeability of the rock.The contribution of the permeability of the straight crack exceeds 94.6%,while that of the permeability of the fractured crack is greater than 86.1%.The disparity in the contribution of these two crack structures is evident at 350℃-550℃.展开更多
In the last decade,numerous physical modification methods have been introduced to enhance triboelectric nanogenerator(TENG)performance although they generally require complex and multiple fabrication processes.This st...In the last decade,numerous physical modification methods have been introduced to enhance triboelectric nanogenerator(TENG)performance although they generally require complex and multiple fabrication processes.This study proposes a facile fabrication process for Poly(vinylidene fluoride)(PVDF)nanofiber(NF)mats incorporating additive and nonadditive physical modifications.Patterned PVDF NF mats are prepared by electrospinning using a metal mesh as the NF collector.As a negative triboelectric material,the TENG with the patterned PVDF NF mat exhibits superior performance owing to the engineered morphology of the contact layer.PVDF is crucial in TENGs owing to its superior ferroelectric properties and surface charge density when combined with specific electroceramics.Hence,the synergy of the physical modification methods is achieved by incorporating BaTiO3(BTO)nanoparticles(NPs)into the PVDF.By functionalizing BTO NPs with polydopamine,the TENG performance is further improved owing to the enhanced dispersion of NPs and improved crystallinity of the PVDF chains.Utilizing large NPs produces a nanopatterning effect on the NF surface,thereby resulting in the hierarchical structure of the NF mats.The source of the voltage signals from the TENG is analyzed using fast Fourier transform.展开更多
Because of the increase in the transmission voltage levels,the demand for insulation reliability of power transformers has increasingly become critical.Cellulose insulating paper is the main insulating component of po...Because of the increase in the transmission voltage levels,the demand for insulation reliability of power transformers has increasingly become critical.Cellulose insulating paper is the main insulating component of power transformers.To improve the insulation level of ultrahigh voltage transformers and reduce their weight and size,reducing the dielectric constant of oil-immersed cellulose insulating paper is highly desired.Cellulose is used to produce power-transformer insulating papers owing to its excellent electrical properties,renewability,biodegradability and abundance.The dielectric constant of a cellulose insulating paper can be effectively reduced by chemical or physical modification.This study presents an overview of the foreign and domestic research status of the use of modification technology to reduce the dielectric constant of cellulose insulating papers.All the mentioned methods are analyzed in this study.Finally,some recommendations for future modified cellulose insulating paper research and applications are proposed.This paper can provide a reference for further research on low dielectric constant cellulose insulating paper in the future.展开更多
The preparation of bioactive materials with good film-forming properties has become a hot research topic nowadays in recent years.In this study,an edible protein film with good mechanical and barrier properties was ma...The preparation of bioactive materials with good film-forming properties has become a hot research topic nowadays in recent years.In this study,an edible protein film with good mechanical and barrier properties was made from soybean protein isolate(SPI)in terms of physical modification.Specifically,the SPI was treated by dielectric barrier discharge cold plasma(DBD-CP)via modified atmosphere packaging(MAP).The effects of oxygen content in MAP on the structure SPI as well as its edible film surface microstructure,mechanical properties,barrier properties and opacity were all investigated.The results showed that the particle size of SPI gradually decreased with the increase of oxygen content.In addition,the surface of the resulting film became smoother and more detailed.At the same time,the elongation at break(EB),water vapor performance(WVP)and opacity of the edible film were significantly improved(p<0.05).The functional properties of the edible film were most significantly improved when the oxygen content was 50%.Compared with control samples,the EB of the film and water contact angle increased by 122.60%and 47.70%,while the WVP and opacity decreased by 19.28%and 27.40%,respectively.Therefore,the MAP-assisted DBD-CP method has the potential of modification of edible protein film with good functional properties and facilitates the application of edible SPI film in various fields.展开更多
基金funded by the Open Research Fund of the State Key Laboratory for Fine Exploration and Intelligent Development of Coal Resources,China University of Mining and Technology(Grant No.SKLCRSM23KF018)the National Natural Science Foundation of China(Grant No.52104144)the National Key R&D Program of China(Grant No.2019YFA0705501).
文摘In the context of convection-heating-based in situ oil shale retorting,fractures serve as primary pathways for fluid migration and product extraction.This study investigates the permeability and microstructural evolution of oil shale during water vapor injection in single-fracture and no-fracture scenarios.Three types of oil shale are investigated:intact oil shale,oil shale with a single straight crack,and oil shale with a single hydraulic crack.With increasing water vapor temperature,the permeabilities of the intact oil shale and oil shale with a fractured crack exhibit a trend of initial increase,followed by a decrease,and then a subsequent increase.However,the permeability of oil shale with a single straight crack consistently increases and exceeds that of oil shale with a fractured crack.The temperaturedependent permeability changes in fractured oil shale-a slight decrease in fracture cracks and a gradual increase in straight cracks-mainly occur in the range of 300℃-350℃.The permeability of oil shale with a straight crack is approximately three times that of oil shale with a fractured crack.This is attributed to the retention of viscous asphaltene and the frictional resistance caused by the rough fracture structure.For the oil shale with a single crack,the crack permeability has a dominant influence on the overall permeability of the rock.The contribution of the permeability of the straight crack exceeds 94.6%,while that of the permeability of the fractured crack is greater than 86.1%.The disparity in the contribution of these two crack structures is evident at 350℃-550℃.
基金supported by the Research Program funded by the SeoulTech(Seoul National University of Science and Technology).
文摘In the last decade,numerous physical modification methods have been introduced to enhance triboelectric nanogenerator(TENG)performance although they generally require complex and multiple fabrication processes.This study proposes a facile fabrication process for Poly(vinylidene fluoride)(PVDF)nanofiber(NF)mats incorporating additive and nonadditive physical modifications.Patterned PVDF NF mats are prepared by electrospinning using a metal mesh as the NF collector.As a negative triboelectric material,the TENG with the patterned PVDF NF mat exhibits superior performance owing to the engineered morphology of the contact layer.PVDF is crucial in TENGs owing to its superior ferroelectric properties and surface charge density when combined with specific electroceramics.Hence,the synergy of the physical modification methods is achieved by incorporating BaTiO3(BTO)nanoparticles(NPs)into the PVDF.By functionalizing BTO NPs with polydopamine,the TENG performance is further improved owing to the enhanced dispersion of NPs and improved crystallinity of the PVDF chains.Utilizing large NPs produces a nanopatterning effect on the NF surface,thereby resulting in the hierarchical structure of the NF mats.The source of the voltage signals from the TENG is analyzed using fast Fourier transform.
基金This work was supported by the National Natural Science Foundation of China(Grant Nos.51977114 and 51867003)Bagui Young Scholars Program(Grant No.2019AQ16)China Postdoctoral Science Foundation(2022MD713732).
文摘Because of the increase in the transmission voltage levels,the demand for insulation reliability of power transformers has increasingly become critical.Cellulose insulating paper is the main insulating component of power transformers.To improve the insulation level of ultrahigh voltage transformers and reduce their weight and size,reducing the dielectric constant of oil-immersed cellulose insulating paper is highly desired.Cellulose is used to produce power-transformer insulating papers owing to its excellent electrical properties,renewability,biodegradability and abundance.The dielectric constant of a cellulose insulating paper can be effectively reduced by chemical or physical modification.This study presents an overview of the foreign and domestic research status of the use of modification technology to reduce the dielectric constant of cellulose insulating papers.All the mentioned methods are analyzed in this study.Finally,some recommendations for future modified cellulose insulating paper research and applications are proposed.This paper can provide a reference for further research on low dielectric constant cellulose insulating paper in the future.
基金National Key Research and Development Program of China for Young Scientists(2022YFF1102600)National Natural Science Foundation of China(32172306 and 32101618)+3 种基金QingLan Project and Youth Science Fund of Jiangsu Province(BK20200832 and BK20211291)Youth Top Talents in Grain Industry of China(QN2022205)Key Research and Development Program of Jiangsu and Zhejiang Province(BE2023347 and 2022C02020)A Project Funded by the Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD).
文摘The preparation of bioactive materials with good film-forming properties has become a hot research topic nowadays in recent years.In this study,an edible protein film with good mechanical and barrier properties was made from soybean protein isolate(SPI)in terms of physical modification.Specifically,the SPI was treated by dielectric barrier discharge cold plasma(DBD-CP)via modified atmosphere packaging(MAP).The effects of oxygen content in MAP on the structure SPI as well as its edible film surface microstructure,mechanical properties,barrier properties and opacity were all investigated.The results showed that the particle size of SPI gradually decreased with the increase of oxygen content.In addition,the surface of the resulting film became smoother and more detailed.At the same time,the elongation at break(EB),water vapor performance(WVP)and opacity of the edible film were significantly improved(p<0.05).The functional properties of the edible film were most significantly improved when the oxygen content was 50%.Compared with control samples,the EB of the film and water contact angle increased by 122.60%and 47.70%,while the WVP and opacity decreased by 19.28%and 27.40%,respectively.Therefore,the MAP-assisted DBD-CP method has the potential of modification of edible protein film with good functional properties and facilitates the application of edible SPI film in various fields.
