[Objective] The deliver amount and deliver rate of heavy metal elements during smoking were studied, which could provide a reference for reducing the damage of cigarette products. [Method] Two pretreatment methodsof m...[Objective] The deliver amount and deliver rate of heavy metal elements during smoking were studied, which could provide a reference for reducing the damage of cigarette products. [Method] Two pretreatment methodsof microwave di- gestion and acid extraction were used to process the ash content, the total particu- late matter of mainstream smoke （TPM） and cigarette filter. Detection results of heavy metal elements were compared by the two methods. [Result] The microwave digestion method was better than acid solution extraction method on analysis of TPM, but presented disadvantages on analysis of ash and filter. Meanwhile, the migration amount and rate were studied and resultsshowed that most heavy metal elements were escaped along with sidestream smoke between 66.89% and 95.48%, and almost all Hg escaped through sidestream smoke. Other heavy metal elements, except Hg, were separately found in ash, TPM and filter. Cr, Ni, As and Se were mostly residual in ash, followed by TPM, and filter had the least, while Cd and Pb were just in the reverse order. Normally, 5% or less heavy metal elements were transferred to TPM, only a small part of which could reach 5%-10%. [Conclusion] Most of the heavy metal elements are taken by sidestream smoke, ash and filter, while the migration amounts to mainstream smoke are extremely low.展开更多
Bilayer graphene(BLG)shows great application prospect and potential in next-generation electronics because of its unique electrical and mechanical properties.However,the scalable synthesis of large-area high-quality B...Bilayer graphene(BLG)shows great application prospect and potential in next-generation electronics because of its unique electrical and mechanical properties.However,the scalable synthesis of large-area high-quality BLG films is still a great challenge,despite the maturity of chemical vapor deposition(CVD)technique.In this study,we report a robust method to grow BLGs on flat,softened Cu foils by atmospheric pressure CVD.A moderate amount of residual oxygen accelerates the growth of BLG domains while suppressing the formation of multilayers.Raising the nucleation density at low hydrogen pressure efficiently increases the film continuity.Based on the optimized CVD process,the growth of graphene films on 4×4 cm^2 Cu foils with an average BLG coverage of 76%is achieved.The morphology and structure characterizations demonstrate a high quality of the BLG.Dual gate field-effect transistors are investigated based on AB-stacked BLG,with a tunable bandgap and high carrier mobility of up to 6790 cm2 V^−1 s^−1 at room temperature.展开更多
In this paper,bottom contact organic thin-film transistor(OTFT)gas sensors were prepared.Silicon dioxide(SiO2)and titanium/aurum(Ti/Au)were used as the insulating layer and the electrode for the device,respectively.Th...In this paper,bottom contact organic thin-film transistor(OTFT)gas sensors were prepared.Silicon dioxide(SiO2)and titanium/aurum(Ti/Au)were used as the insulating layer and the electrode for the device,respectively.The multi-walled carbon nanotubes(MWCNTs)/α-sexithiophene(α-6T)bilayer films were used as the active layer,andα-6T single layer sensitive film was also prepared for comparison purpose.The electrical and trace NO2-sening properties of these two OTFT gas sensors were tested and analyzed.The results showed that,the OTFT device based on MWCNTs/α-6T bilayer had obviously better electrical properties,better stabilities and higher NO2-sening response values than the device withα-6T single layer,in which both the carrier mobility(μ)and on/off current ratio enhanced two order of magnitude.The improved performance of bilayer OTFT can be explained that MWCNTs acted as highly conducting bridges connecting the crystalline terraces in theα-6T film.Threshold voltage(VT),carrier mobility,on/off current ratio and grid current which showed extremely similar variation trend as source-drain current,were optional parameters to reveal the gas-sensing characteristic of OTFT gas sensors.Morphology analysis showed that the special feature of MWCNTs had certain influence on the gas-sensing properties.展开更多
文摘[Objective] The deliver amount and deliver rate of heavy metal elements during smoking were studied, which could provide a reference for reducing the damage of cigarette products. [Method] Two pretreatment methodsof microwave di- gestion and acid extraction were used to process the ash content, the total particu- late matter of mainstream smoke （TPM） and cigarette filter. Detection results of heavy metal elements were compared by the two methods. [Result] The microwave digestion method was better than acid solution extraction method on analysis of TPM, but presented disadvantages on analysis of ash and filter. Meanwhile, the migration amount and rate were studied and resultsshowed that most heavy metal elements were escaped along with sidestream smoke between 66.89% and 95.48%, and almost all Hg escaped through sidestream smoke. Other heavy metal elements, except Hg, were separately found in ash, TPM and filter. Cr, Ni, As and Se were mostly residual in ash, followed by TPM, and filter had the least, while Cd and Pb were just in the reverse order. Normally, 5% or less heavy metal elements were transferred to TPM, only a small part of which could reach 5%-10%. [Conclusion] Most of the heavy metal elements are taken by sidestream smoke, ash and filter, while the migration amounts to mainstream smoke are extremely low.
基金This work was supported by China Postdoctoral Science Foundation(2018M642831)Shenzhen Science and Technology Project(JCYJ20180507183904841).
文摘Bilayer graphene(BLG)shows great application prospect and potential in next-generation electronics because of its unique electrical and mechanical properties.However,the scalable synthesis of large-area high-quality BLG films is still a great challenge,despite the maturity of chemical vapor deposition(CVD)technique.In this study,we report a robust method to grow BLGs on flat,softened Cu foils by atmospheric pressure CVD.A moderate amount of residual oxygen accelerates the growth of BLG domains while suppressing the formation of multilayers.Raising the nucleation density at low hydrogen pressure efficiently increases the film continuity.Based on the optimized CVD process,the growth of graphene films on 4×4 cm^2 Cu foils with an average BLG coverage of 76%is achieved.The morphology and structure characterizations demonstrate a high quality of the BLG.Dual gate field-effect transistors are investigated based on AB-stacked BLG,with a tunable bandgap and high carrier mobility of up to 6790 cm2 V^−1 s^−1 at room temperature.
基金supported by the Natural Natural Science Foundation of China(Grant Nos.61176066,61101031)
文摘In this paper,bottom contact organic thin-film transistor(OTFT)gas sensors were prepared.Silicon dioxide(SiO2)and titanium/aurum(Ti/Au)were used as the insulating layer and the electrode for the device,respectively.The multi-walled carbon nanotubes(MWCNTs)/α-sexithiophene(α-6T)bilayer films were used as the active layer,andα-6T single layer sensitive film was also prepared for comparison purpose.The electrical and trace NO2-sening properties of these two OTFT gas sensors were tested and analyzed.The results showed that,the OTFT device based on MWCNTs/α-6T bilayer had obviously better electrical properties,better stabilities and higher NO2-sening response values than the device withα-6T single layer,in which both the carrier mobility(μ)and on/off current ratio enhanced two order of magnitude.The improved performance of bilayer OTFT can be explained that MWCNTs acted as highly conducting bridges connecting the crystalline terraces in theα-6T film.Threshold voltage(VT),carrier mobility,on/off current ratio and grid current which showed extremely similar variation trend as source-drain current,were optional parameters to reveal the gas-sensing characteristic of OTFT gas sensors.Morphology analysis showed that the special feature of MWCNTs had certain influence on the gas-sensing properties.
