Flexible p–n thermoelectric generator(TEG)technology has rapidly advanced with power enhancement and size reduction.To achieve a stable power supply and highly efficient energy conversion,absolute chemical stability ...Flexible p–n thermoelectric generator(TEG)technology has rapidly advanced with power enhancement and size reduction.To achieve a stable power supply and highly efficient energy conversion,absolute chemical stability of n-type materials is essential to ensuring large temperature differences between device terminals and ambient stability.With the aim of improving the long-term stability of the n-type operation of carbon nanotubes(CNTs)in air and water,this study uses cationic surfactants,such as octylene-1,8-bis(dimethyldodecylammonium bromide)(12-8-12),a gemini surfactant,to stabilize the nanotubes in a coating,which retains the n-doped state for more than 28 days after exposure to air and water in experiments.TEGs with 10 p-n units of 12-8-12/CNT(n-type)and sodium dodecylbenzene sulfonate/CNT(p-type)layers are manufactured,and their water stability is evaluated.The initial maximum output of 16.1μW(75 K temperature difference)is retained after water immersion for 40 days without using a sealant to prevent TEG module degradation.The excellent stability of these CNT-based TEGs makes them suitable for underwater applications,such as battery-free health monitoring and information gathering systems,and facilitates the development of soft electronics.展开更多
Water-preservation mining is one of the most important parts of the ‘Green Mining' technology system,which can realize the effective regulation of groundwater resources by controlling strata movement,changing pas...Water-preservation mining is one of the most important parts of the ‘Green Mining' technology system,which can realize the effective regulation of groundwater resources by controlling strata movement,changing passive prevention and governance of water disasters to active conservation and utilization of groundwater resources and thus obtaining coal and water simultaneously in mining.The concept of water-resistant key strata further enriches the content of the key stratum theory and provides a theoretical basis for water-preservation mining.In order to realize the idea of water-resistant key strata as a guideline in the design of water-preservation mining and engineering applications,the conditions for discrimination in the process of water-resistant key strata,we have presented a mechanical model,as well as its corresponding computer program,based on a large number of theoretical analyses and field measurements,as well as on a comprehensive consideration of the position,structural stability and seepage stability of key strata.Practical engineering applications indicate that this discrimination method and its corresponding computer program on water-resistant key strata are accurate and reliable and can satisfy the actual design needs of water-preservation mining and thus have instructional importance for water-preservation mining in mining areas lacking water.展开更多
A water-resistant key strata model of a goaf floor prior to main roof weighting was developed to explore the relationship between water inrush from the floor and main roof weighting. The stress distribution,broken cha...A water-resistant key strata model of a goaf floor prior to main roof weighting was developed to explore the relationship between water inrush from the floor and main roof weighting. The stress distribution,broken characteristics, and the risk area for water inrush of the water-resistant key strata were analysed using elastic thin plate theory. The formula of the maximum water pressure tolerated by the waterresistant key strata was deduced. The effects of the caved load of the goaf, the goaf size prior to main roof weighting, the advancing distance of the workface or weighting step, and the thickness of the waterresistant key strata on the breaking and instability of the water-resistant key strata were analysed.The results indicate that the water inrush from the floor can be predicted and prevented by controlling the initial or periodic weighting step with measures such as artificial forced caving, thus achieving safe mining conditions above confined aquifers. The findings provide an important theoretical basis for determining water inrush from the floor when mining above confined aquifers.展开更多
Chemical modification of cassava starch by transesterification of a vegetable oil(palm kernel oil)using aluminum chloride as a Lewis acid catalyst was achieved under relatively mild conditions(temperature 60–110°...Chemical modification of cassava starch by transesterification of a vegetable oil(palm kernel oil)using aluminum chloride as a Lewis acid catalyst was achieved under relatively mild conditions(temperature 60–110°C;atmospheric pressure).The reaction was carried out without any additional solvent.The modified starch was characterized by degree of substitution(DS),FTIR,X-ray diffraction and thermal analysis.DS of 0.09 to 0.53 were obtained.The cassava starch presented an X-ray diffraction pattern of a type A starch.X-ray analyses showed that the reaction did not significantly affect the crystallinity of starch.The modified starch films(MStF)adsorbed less water than the reference native starch film(NStF)at all the relative humidities investigated.The MStF were also less soluble in water.The tensile tests showed an increase of the strength and a decrease of the flexibility of MStF compared to the reference NStF.The results showed that this chemical route could be used to increase the water resistance of starch-based materials.展开更多
Regenerated cellulose films with water-resistance were obtained by an improved method ofpreparing cellulose cuoxam solution from pulps of agricultural wastes (linters, wheat straw, reedand Bamao). Experimental results...Regenerated cellulose films with water-resistance were obtained by an improved method ofpreparing cellulose cuoxam solution from pulps of agricultural wastes (linters, wheat straw, reedand Bamao). Experimental results showed that the mechanical properties of both the dry. and wetfilms were excellent. Data from IR, SEM and tensile strength measurements implied that thesignificant improvement of water-resistance of the films was due to the cohesion between the thinTung oil covers with hydrophobicity and the regenerated cellulose films. The films werecompletely biodegraded after being buried in soil for 100 days. The transmittance of the filmsderived from linter and reed in visible band range were 80-90%.展开更多
Development of "green" multi-functional air filters with features such as excellent filtration efficiency eco-friendliness, and environmental stability are critically required to address the increasing concerns of p...Development of "green" multi-functional air filters with features such as excellent filtration efficiency eco-friendliness, and environmental stability are critically required to address the increasing concerns of polluted air. Natural proteins, such as soy protein and gelatin, are attractive candidates as multi-functional air-filtration materials owing to the rich functional groups; however, these bio-materials are vulnerable to moisture, which limits their broad application in practice. In this work, a hydrophobic protein of zein derived from abundant corn is modified for the first time to produce high-performance nanofilters via electrospinning. The zein nanofabrics are fabricated with the aid of a non-toxic solvent and co-electrospinning agent, poly(ethylene oxide). The results reveal that the zein-based nanofabrics show high efficiency for the simultaneous removal of particulate matters of different sizes ranging from 0.1 to 10 btm (〉 99.5%) and certain gaseous toxic chemicals (〉 70%). In addition, the zein nanofabrics show excellent moisture-resistance and good adhesion to the cellulose paper towel used as the air-filter substrate. This study demonstrates that nanofabrics based on hydrophobic natural proteins such as zein are promising materials for developing multi-functional "green" air filters.展开更多
Water-and-mud inrush disasters have become a major challenge in underground engineering for the construction of tunnels in sandstone and slate interbedded Presinian strata.Disaster prediction and prevention rely in pa...Water-and-mud inrush disasters have become a major challenge in underground engineering for the construction of tunnels in sandstone and slate interbedded Presinian strata.Disaster prediction and prevention rely in part on realistic modeling and observation of the disaster process,as well as the identification and examination of the underlying mechanisms.Based on the geological conditions and the historical records of the Xinping Tunnel on the China–Laos Railway,an engineering geological model of the water-and-mud inrush was established.A physical model test that accurately reproduced water-and-mud inrush during tunnel excavation in sandstone and slate interbedded strata was also carried out.Then,testing was conducted that examined the stress and strain,seepage pressure,and high-leakage flow of the surrounding rock.The results indicated that the water-and-mud inrush proceeded through three stages:seepage stage,high-leakage flow stage,and attenuation stage.In essence,the disaster was a catastrophic process,during which the water-resistant stratum was reduced to a critical safety thickness,a water-inrush channel formed,and the water-resistant stratum gradually failed under the influence of excavation unloading and in situ stress–seepage coupling.Parameters such as the stress and strain,seepage pressure,and flow of the surrounding rock had evident stage-related features during water-and-mud inrush,and their variation indicated the formation,development,and evolution of the disaster.As the tunnel face advanced,the trend of the stress–strain curve of the surrounding rock shifted from sluggish to rapid in its speed of increase.The characteristics of strain energy density revealed the erosion and weakening effect of groundwater on the surrounding rock.The seepage pressure and the thickness of the water-resistant stratum had a positive linear relationship,and the flow and thickness a negative linear relationship.There was a pivotal point at which the seepage pressure changed from high to low and the flow shifted from low to high.The thickness of the water-resistant stratum corresponding to the pivotal point was deemed the critical safety thickness.展开更多
Antioxidant biomaterials have attracted much attention in various biomedical fields because of their effective inhibition and elimination of reactive oxygen species(ROS)in pathological tissues.However,the difficulty i...Antioxidant biomaterials have attracted much attention in various biomedical fields because of their effective inhibition and elimination of reactive oxygen species(ROS)in pathological tissues.However,the difficulty in ensuring biocompatibility,biodegradability and bioavailability of antioxidant materials has limited their further development.Novel bioavailable antioxidant materials that are derived from natural resources are urgently needed.Here,an integrated multi-omics method was applied to fabricate antioxidant biomaterials.A key cysteine-rich thrombospondin-1 type Ⅰ repeat-like(TSRL)protein was efficiently discovered from among 1262 adhesive components and then used to create a recombinant protein with a yield of 500 mg L^(-1).The biocompatible TSRL protein was able to self-assemble into either a water-resistant coating through Ca^(2+)-mediated coordination or redox-responsive hydrogels with tunable physical properties.The TSRL-based hydrogels showed stronger 1,1-diphenyl-2-picrylhydrazyl(DPPH)radical scavenging rates than glutathione(GSH)and ascorbic acid(Aa)and protected cells against external oxidative stress significantly more effectively.When topically applied to mice skin,TSRL alleviated epidermal hyperplasia and suppressed the degradation of collagen and elastic fibers caused by ultraviolet radiation B(UVB)irradiation,confirming that it enhanced antioxidant activity in vivo.This is the first study to successfully characterize natural antioxidant biomaterials created from marine invertebrate adhesives,and the findings indicate the excellent prospects of these biomaterials for great applications in tissue regeneration and cosmeceuticals.展开更多
Flexible electromagnetic interference(EMI)shielding films with high stability have shown promising prospect in harsh working conditions such as military,communication,and special protection fields.Herein,flexible aram...Flexible electromagnetic interference(EMI)shielding films with high stability have shown promising prospect in harsh working conditions such as military,communication,and special protection fields.Herein,flexible aramid nanofibers@polypyrrole(ANF@PPy)films with high stability were easily achieved by the in-situ growth of PPy on the surface of ANF and the subsequent pressured-filtration film-forming process.When the amount of pyrrole(Py)monomer is 40μL,the ANF@PPy(AP40)film exhibited excellent EMI shielding performance with shielding effectiveness(SE)of 41.69 dB,tensile strength of 96.01 MPa,and fracture strain of 21.95%at the thickness of 75.76μm.Particularly,the anticipated EMI shielding performance can be maintained even after being heated at 200℃in air,soaked in 3.5%NaCl solution,repeated folding for one million times,or burned directly,indicating superior environmental durability in harsh conditions.Therefore,it is believed that the ANF@PPy films with high stability offer a facile solution for practical protection for high-performance EMI shielding applications.展开更多
In this study,cellulose nanofibers(CNFs)were crossed-linked with glutaraldehyde(GA)under acid condition for tailoring the mechanical properties and water-resistance of nanopaper or films.The impact of carboxyl content...In this study,cellulose nanofibers(CNFs)were crossed-linked with glutaraldehyde(GA)under acid condition for tailoring the mechanical properties and water-resistance of nanopaper or films.The impact of carboxyl content of CNFs,GA concentration,temperature,pH,and reaction time on the crosslinking was investigated,and the process conditions for the crosslinking were optimized.FT-IR analyses showed that CNFs/GA cross-linked nanopaper was successfully fabricated by acetalization between the-OH groups of CNFs and the-CHO groups of GA,resulting in the formation of a dense,three-dimensional network.The elastic modulus of CNFs/GA cross-linked film was 7.66GPa,62.98%higher than that of CNFs film.The water-resistance of the cross-linked CNFs/GA films was improved.The crossed-linked CNFs/GA films was still intact after 24 h after being immersed in water,while the CNFs films almost dissolved completely after 20 min of soaking in water.This method provides a facile route to enhance the elastic modulus and water-resistance of CNFs for potential applications including bullet-proof glass interlayer,flexible electronic device,and new packing materials.展开更多
基金Mazda FoundationTEPCO Memorial FoundationJapan Society for the Promotion of Science,Grant/Award Numbers:19K05633,21K14428。
文摘Flexible p–n thermoelectric generator(TEG)technology has rapidly advanced with power enhancement and size reduction.To achieve a stable power supply and highly efficient energy conversion,absolute chemical stability of n-type materials is essential to ensuring large temperature differences between device terminals and ambient stability.With the aim of improving the long-term stability of the n-type operation of carbon nanotubes(CNTs)in air and water,this study uses cationic surfactants,such as octylene-1,8-bis(dimethyldodecylammonium bromide)(12-8-12),a gemini surfactant,to stabilize the nanotubes in a coating,which retains the n-doped state for more than 28 days after exposure to air and water in experiments.TEGs with 10 p-n units of 12-8-12/CNT(n-type)and sodium dodecylbenzene sulfonate/CNT(p-type)layers are manufactured,and their water stability is evaluated.The initial maximum output of 16.1μW(75 K temperature difference)is retained after water immersion for 40 days without using a sealant to prevent TEG module degradation.The excellent stability of these CNT-based TEGs makes them suitable for underwater applications,such as battery-free health monitoring and information gathering systems,and facilitates the development of soft electronics.
基金supported by the National Natural Science Foundation of China (No.50874103)the National Basic Research Program of China (Nos.2006CB202210 and 2007CB209408)+1 种基金the Natural Science Foundation of Jiangsu Province (No.KB2008135)the Qinglan Project of Jiangsu Province
文摘Water-preservation mining is one of the most important parts of the ‘Green Mining' technology system,which can realize the effective regulation of groundwater resources by controlling strata movement,changing passive prevention and governance of water disasters to active conservation and utilization of groundwater resources and thus obtaining coal and water simultaneously in mining.The concept of water-resistant key strata further enriches the content of the key stratum theory and provides a theoretical basis for water-preservation mining.In order to realize the idea of water-resistant key strata as a guideline in the design of water-preservation mining and engineering applications,the conditions for discrimination in the process of water-resistant key strata,we have presented a mechanical model,as well as its corresponding computer program,based on a large number of theoretical analyses and field measurements,as well as on a comprehensive consideration of the position,structural stability and seepage stability of key strata.Practical engineering applications indicate that this discrimination method and its corresponding computer program on water-resistant key strata are accurate and reliable and can satisfy the actual design needs of water-preservation mining and thus have instructional importance for water-preservation mining in mining areas lacking water.
基金supported by the National Natural Science Foundation of China (Nos. 51404013 and 51674008)the Open Projects of State Key Laboratory of Coal Resources and Safe Mining at the China University of Mining and Technology (No. 13KF01)the Natural Science Foundation of Anhui Province (Nos. 1508085ME77 and 1508085QE89)
文摘A water-resistant key strata model of a goaf floor prior to main roof weighting was developed to explore the relationship between water inrush from the floor and main roof weighting. The stress distribution,broken characteristics, and the risk area for water inrush of the water-resistant key strata were analysed using elastic thin plate theory. The formula of the maximum water pressure tolerated by the waterresistant key strata was deduced. The effects of the caved load of the goaf, the goaf size prior to main roof weighting, the advancing distance of the workface or weighting step, and the thickness of the waterresistant key strata on the breaking and instability of the water-resistant key strata were analysed.The results indicate that the water inrush from the floor can be predicted and prevented by controlling the initial or periodic weighting step with measures such as artificial forced caving, thus achieving safe mining conditions above confined aquifers. The findings provide an important theoretical basis for determining water inrush from the floor when mining above confined aquifers.
文摘Chemical modification of cassava starch by transesterification of a vegetable oil(palm kernel oil)using aluminum chloride as a Lewis acid catalyst was achieved under relatively mild conditions(temperature 60–110°C;atmospheric pressure).The reaction was carried out without any additional solvent.The modified starch was characterized by degree of substitution(DS),FTIR,X-ray diffraction and thermal analysis.DS of 0.09 to 0.53 were obtained.The cassava starch presented an X-ray diffraction pattern of a type A starch.X-ray analyses showed that the reaction did not significantly affect the crystallinity of starch.The modified starch films(MStF)adsorbed less water than the reference native starch film(NStF)at all the relative humidities investigated.The MStF were also less soluble in water.The tensile tests showed an increase of the strength and a decrease of the flexibility of MStF compared to the reference NStF.The results showed that this chemical route could be used to increase the water resistance of starch-based materials.
文摘Regenerated cellulose films with water-resistance were obtained by an improved method ofpreparing cellulose cuoxam solution from pulps of agricultural wastes (linters, wheat straw, reedand Bamao). Experimental results showed that the mechanical properties of both the dry. and wetfilms were excellent. Data from IR, SEM and tensile strength measurements implied that thesignificant improvement of water-resistance of the films was due to the cohesion between the thinTung oil covers with hydrophobicity and the regenerated cellulose films. The films werecompletely biodegraded after being buried in soil for 100 days. The transmittance of the filmsderived from linter and reed in visible band range were 80-90%.
文摘Development of "green" multi-functional air filters with features such as excellent filtration efficiency eco-friendliness, and environmental stability are critically required to address the increasing concerns of polluted air. Natural proteins, such as soy protein and gelatin, are attractive candidates as multi-functional air-filtration materials owing to the rich functional groups; however, these bio-materials are vulnerable to moisture, which limits their broad application in practice. In this work, a hydrophobic protein of zein derived from abundant corn is modified for the first time to produce high-performance nanofilters via electrospinning. The zein nanofabrics are fabricated with the aid of a non-toxic solvent and co-electrospinning agent, poly(ethylene oxide). The results reveal that the zein-based nanofabrics show high efficiency for the simultaneous removal of particulate matters of different sizes ranging from 0.1 to 10 btm (〉 99.5%) and certain gaseous toxic chemicals (〉 70%). In addition, the zein nanofabrics show excellent moisture-resistance and good adhesion to the cellulose paper towel used as the air-filter substrate. This study demonstrates that nanofabrics based on hydrophobic natural proteins such as zein are promising materials for developing multi-functional "green" air filters.
基金the National High-Speed Rail United Foundation of China(No.U1934213)。
文摘Water-and-mud inrush disasters have become a major challenge in underground engineering for the construction of tunnels in sandstone and slate interbedded Presinian strata.Disaster prediction and prevention rely in part on realistic modeling and observation of the disaster process,as well as the identification and examination of the underlying mechanisms.Based on the geological conditions and the historical records of the Xinping Tunnel on the China–Laos Railway,an engineering geological model of the water-and-mud inrush was established.A physical model test that accurately reproduced water-and-mud inrush during tunnel excavation in sandstone and slate interbedded strata was also carried out.Then,testing was conducted that examined the stress and strain,seepage pressure,and high-leakage flow of the surrounding rock.The results indicated that the water-and-mud inrush proceeded through three stages:seepage stage,high-leakage flow stage,and attenuation stage.In essence,the disaster was a catastrophic process,during which the water-resistant stratum was reduced to a critical safety thickness,a water-inrush channel formed,and the water-resistant stratum gradually failed under the influence of excavation unloading and in situ stress–seepage coupling.Parameters such as the stress and strain,seepage pressure,and flow of the surrounding rock had evident stage-related features during water-and-mud inrush,and their variation indicated the formation,development,and evolution of the disaster.As the tunnel face advanced,the trend of the stress–strain curve of the surrounding rock shifted from sluggish to rapid in its speed of increase.The characteristics of strain energy density revealed the erosion and weakening effect of groundwater on the surrounding rock.The seepage pressure and the thickness of the water-resistant stratum had a positive linear relationship,and the flow and thickness a negative linear relationship.There was a pivotal point at which the seepage pressure changed from high to low and the flow shifted from low to high.The thickness of the water-resistant stratum corresponding to the pivotal point was deemed the critical safety thickness.
基金supported by the Natural Science Foundation of China(32071371,41776177)the Fundamental Research Funds for the Central Universities(201822024,202061011)the China Postdoctoral Science Foundation(2020M672143).
文摘Antioxidant biomaterials have attracted much attention in various biomedical fields because of their effective inhibition and elimination of reactive oxygen species(ROS)in pathological tissues.However,the difficulty in ensuring biocompatibility,biodegradability and bioavailability of antioxidant materials has limited their further development.Novel bioavailable antioxidant materials that are derived from natural resources are urgently needed.Here,an integrated multi-omics method was applied to fabricate antioxidant biomaterials.A key cysteine-rich thrombospondin-1 type Ⅰ repeat-like(TSRL)protein was efficiently discovered from among 1262 adhesive components and then used to create a recombinant protein with a yield of 500 mg L^(-1).The biocompatible TSRL protein was able to self-assemble into either a water-resistant coating through Ca^(2+)-mediated coordination or redox-responsive hydrogels with tunable physical properties.The TSRL-based hydrogels showed stronger 1,1-diphenyl-2-picrylhydrazyl(DPPH)radical scavenging rates than glutathione(GSH)and ascorbic acid(Aa)and protected cells against external oxidative stress significantly more effectively.When topically applied to mice skin,TSRL alleviated epidermal hyperplasia and suppressed the degradation of collagen and elastic fibers caused by ultraviolet radiation B(UVB)irradiation,confirming that it enhanced antioxidant activity in vivo.This is the first study to successfully characterize natural antioxidant biomaterials created from marine invertebrate adhesives,and the findings indicate the excellent prospects of these biomaterials for great applications in tissue regeneration and cosmeceuticals.
基金the Science and Technology Commission of Shanghai Municipality(Nos.20230742300 and 18595800700)the project of“joint assignment”in Shanghai University led by Prof.
文摘Flexible electromagnetic interference(EMI)shielding films with high stability have shown promising prospect in harsh working conditions such as military,communication,and special protection fields.Herein,flexible aramid nanofibers@polypyrrole(ANF@PPy)films with high stability were easily achieved by the in-situ growth of PPy on the surface of ANF and the subsequent pressured-filtration film-forming process.When the amount of pyrrole(Py)monomer is 40μL,the ANF@PPy(AP40)film exhibited excellent EMI shielding performance with shielding effectiveness(SE)of 41.69 dB,tensile strength of 96.01 MPa,and fracture strain of 21.95%at the thickness of 75.76μm.Particularly,the anticipated EMI shielding performance can be maintained even after being heated at 200℃in air,soaked in 3.5%NaCl solution,repeated folding for one million times,or burned directly,indicating superior environmental durability in harsh conditions.Therefore,it is believed that the ANF@PPy films with high stability offer a facile solution for practical protection for high-performance EMI shielding applications.
基金the State Key Laboratory of Pulp and Paper Engineering,South China University of Technology(Grant No.2015C09,2016PY01)Natural Science Foundation of Guangdong Province(Grant No.2016A030311052).
文摘In this study,cellulose nanofibers(CNFs)were crossed-linked with glutaraldehyde(GA)under acid condition for tailoring the mechanical properties and water-resistance of nanopaper or films.The impact of carboxyl content of CNFs,GA concentration,temperature,pH,and reaction time on the crosslinking was investigated,and the process conditions for the crosslinking were optimized.FT-IR analyses showed that CNFs/GA cross-linked nanopaper was successfully fabricated by acetalization between the-OH groups of CNFs and the-CHO groups of GA,resulting in the formation of a dense,three-dimensional network.The elastic modulus of CNFs/GA cross-linked film was 7.66GPa,62.98%higher than that of CNFs film.The water-resistance of the cross-linked CNFs/GA films was improved.The crossed-linked CNFs/GA films was still intact after 24 h after being immersed in water,while the CNFs films almost dissolved completely after 20 min of soaking in water.This method provides a facile route to enhance the elastic modulus and water-resistance of CNFs for potential applications including bullet-proof glass interlayer,flexible electronic device,and new packing materials.