The CO2-induced capillary blocking in anode flow field is one of the key adverse factors to reduce the performance of a micro-direct methanol fuel cell(l DMFC). In order to solve this problem, new polycarbonate(PC) fl...The CO2-induced capillary blocking in anode flow field is one of the key adverse factors to reduce the performance of a micro-direct methanol fuel cell(l DMFC). In order to solve this problem, new polycarbonate(PC) flow field plates with nested arrangement of hydrophilic fuel channels and superhydrophobic gas channels were designed,fabricated, and tested in this work. The gas channels were treated with solvent-induced crystallization using acetone solution. The superhydrophobicity with 160° water contact angle and 2° tilting angle was obtained on the PC substrates. A dummy cell using hydrogen peroxide decomposition reaction and a test loop were separately set up to evaluate the flow fields' performance. It was found that a 37 % pressure drop decrease can be obtained in the new serpentine flow field compared with that of the conventional one. The benefit of the new flow field to remove gas bubbles was also confirmed by an in situ visualization study on the dummy cell. Results show that the auxiliary superhydrophobic gas channels can speed up the discharge of the gas bubbles from the flow field, which will in turn improve the l DMFC performance.展开更多
Bark beetles Tomicus yunnanensis and T.minor are two important pests of Pinus yunnanensis and can cause massive death of pine trees.In this study,we examined several traits related to photosynthesis in P.yunnanensis a...Bark beetles Tomicus yunnanensis and T.minor are two important pests of Pinus yunnanensis and can cause massive death of pine trees.In this study,we examined several traits related to photosynthesis in P.yunnanensis and their relationship with antibiotic defense responses after joint attack by the two bark beetles at the shoot and the trunk stages.When shoots were attacked by the beetles,the abundance of chlorophylls,carotenoids,and the rates of net photosynthesis(Pn)and transpiration(E)decreased in needles,while the levels of superoxide dismutase and malondialdehyde remained unchanged in both needles and phloem.The activity of peroxidases also remained unchanged in needles,but increased in phloem.The activity of catalases increased in both needles and phloem.When trunks were attacked by the bark beetles,chlorophyll abundance,Pn,E,and antioxidative enzyme activities all declined,and the declines were more pronounced than in the attacked shoots.A decrease in protein concentrations was also observed in needles and phloem from the attacked pines.Attack on shoots by the bark beetles suppressed host defense and provided a favorable environment for larval growth and development,resulting in long-term decline of pine growth potential.The results suggest that attacks on trunks by beetles caused more severe damage to host trees than attacks on shoots.展开更多
Electrohydrodynamicjet （E-Jet） is an approach to the fabrication of micro/nano-structures by the use of electrical forces. In this process, the liquid is subjected to electrical and mechanical forces to form a liqui...Electrohydrodynamicjet （E-Jet） is an approach to the fabrication of micro/nano-structures by the use of electrical forces. In this process, the liquid is subjected to electrical and mechanical forces to form a liquid jet, which is further disintegrated into droplets. The major advantage of the E-Jet technique is that the sizes of the jet formed can be at the nanoscale far smaller than the nozzle size, which can realize high printing resolution with less risk of nozzle blockage. The E-Jet technique, which mainly includes E-Jet deposition and E-Jet printing, has a wide range of applications in the fabrication ofmicro/nano-structures for micro/nano-electromechanical system devices. This tech- nique is also considered a micro/nano-fabrication method with a great potential for commercial use. This study mainly reviews the E-Jet deposition/printing fundamentals, fabrication process, and applications.展开更多
Polymer nanowire(NW)organic field-effect transistors(OFETs)integrated on highly aligned large-area flexible substrates are candidate structures for the development of high-performance flexible electronics.This work pr...Polymer nanowire(NW)organic field-effect transistors(OFETs)integrated on highly aligned large-area flexible substrates are candidate structures for the development of high-performance flexible electronics.This work presents a universal technique,coaxial focused electrohydrodynamic jet(CFEJ)printing technology,to fabricate highly aligned 90-nm-diameter polymer arrays.This method allows for the preparation of uniformly shaped and precisely positioned nanowires directly on flexible substrates without transfer,thus ensuring their electrical properties.Using indacenodithiophene-co-benzothiadiazole(IDT-BT)and poly(9,9-dioctylfluorene-co-benzothiadiazole)(F8-BT)as example materials,5 cm^(2) arrays were prepared with only minute size variations,which is extremely difficult to do using previously reported methods.According to 2D-GIXRD analysis,the molecules inside the nanowires mainly adopted face-onπ-stacking crystallite arrangements.This is quite different from the mixed arrangement of thin films.Nanowire-based OFETs exhibited a high average hole mobility of 1.1 cm^(2) V^(−1) s^(−1) and good device uniformity,indicating the applicability of CFEJ printing as a potential batch manufacturing and integration process for high-performance,scalable polymer nanowire-based OFET circuits.This technique can be used to fabricate various polymer arrays,enabling the use of organic polymer semiconductors in large-area,high-performance electronic devices and providing a new path for the fabrication of flexible displays and wearable electronics in the future.展开更多
基金financially supported by the National Natural Science Foundation of China (Nos. 51275076, 51475081)
文摘The CO2-induced capillary blocking in anode flow field is one of the key adverse factors to reduce the performance of a micro-direct methanol fuel cell(l DMFC). In order to solve this problem, new polycarbonate(PC) flow field plates with nested arrangement of hydrophilic fuel channels and superhydrophobic gas channels were designed,fabricated, and tested in this work. The gas channels were treated with solvent-induced crystallization using acetone solution. The superhydrophobicity with 160° water contact angle and 2° tilting angle was obtained on the PC substrates. A dummy cell using hydrogen peroxide decomposition reaction and a test loop were separately set up to evaluate the flow fields' performance. It was found that a 37 % pressure drop decrease can be obtained in the new serpentine flow field compared with that of the conventional one. The benefit of the new flow field to remove gas bubbles was also confirmed by an in situ visualization study on the dummy cell. Results show that the auxiliary superhydrophobic gas channels can speed up the discharge of the gas bubbles from the flow field, which will in turn improve the l DMFC performance.
基金supported by the Fundamental Scientific Research Fund for Central Non-profit Research Institute(Grant No.CAFYBB2016MA006)the Public Welfare Special Fund Project of Forestry Industry of State Forestry Administration of China(Grant No.200904052)
文摘Bark beetles Tomicus yunnanensis and T.minor are two important pests of Pinus yunnanensis and can cause massive death of pine trees.In this study,we examined several traits related to photosynthesis in P.yunnanensis and their relationship with antibiotic defense responses after joint attack by the two bark beetles at the shoot and the trunk stages.When shoots were attacked by the beetles,the abundance of chlorophylls,carotenoids,and the rates of net photosynthesis(Pn)and transpiration(E)decreased in needles,while the levels of superoxide dismutase and malondialdehyde remained unchanged in both needles and phloem.The activity of peroxidases also remained unchanged in needles,but increased in phloem.The activity of catalases increased in both needles and phloem.When trunks were attacked by the bark beetles,chlorophyll abundance,Pn,E,and antioxidative enzyme activities all declined,and the declines were more pronounced than in the attacked shoots.A decrease in protein concentrations was also observed in needles and phloem from the attacked pines.Attack on shoots by the bark beetles suppressed host defense and provided a favorable environment for larval growth and development,resulting in long-term decline of pine growth potential.The results suggest that attacks on trunks by beetles caused more severe damage to host trees than attacks on shoots.
文摘Electrohydrodynamicjet （E-Jet） is an approach to the fabrication of micro/nano-structures by the use of electrical forces. In this process, the liquid is subjected to electrical and mechanical forces to form a liquid jet, which is further disintegrated into droplets. The major advantage of the E-Jet technique is that the sizes of the jet formed can be at the nanoscale far smaller than the nozzle size, which can realize high printing resolution with less risk of nozzle blockage. The E-Jet technique, which mainly includes E-Jet deposition and E-Jet printing, has a wide range of applications in the fabrication ofmicro/nano-structures for micro/nano-electromechanical system devices. This tech- nique is also considered a micro/nano-fabrication method with a great potential for commercial use. This study mainly reviews the E-Jet deposition/printing fundamentals, fabrication process, and applications.
基金This research was supported by the National Key R&D Program of China(Grant No.2018YFA0703200,D.W.)National Natural Science Foundation of China(51975104 and 62074138,D.W.52003274,Z.Z.)+2 种基金the Fundamental Research Funds for the Central Universities(DUT22LAB405,DUT22QN227)Defense Industrial Technology Development Program(JCKY2020204B004)Ningbo Institute of Dalian University of Technology.The 2D-GIXRD data were obtained at 1W1A,Beijing Synchrotron Radiation Facility.The authors gratefully acknowledge the assistance of researchers of the Diffuse X-ray Scattering Station during the experiments.Special thanks are due to Dr.Cai Rui in the Instrumental Analysis Center of Dalian University of Technology for assistance with AFM analysis.
文摘Polymer nanowire(NW)organic field-effect transistors(OFETs)integrated on highly aligned large-area flexible substrates are candidate structures for the development of high-performance flexible electronics.This work presents a universal technique,coaxial focused electrohydrodynamic jet(CFEJ)printing technology,to fabricate highly aligned 90-nm-diameter polymer arrays.This method allows for the preparation of uniformly shaped and precisely positioned nanowires directly on flexible substrates without transfer,thus ensuring their electrical properties.Using indacenodithiophene-co-benzothiadiazole(IDT-BT)and poly(9,9-dioctylfluorene-co-benzothiadiazole)(F8-BT)as example materials,5 cm^(2) arrays were prepared with only minute size variations,which is extremely difficult to do using previously reported methods.According to 2D-GIXRD analysis,the molecules inside the nanowires mainly adopted face-onπ-stacking crystallite arrangements.This is quite different from the mixed arrangement of thin films.Nanowire-based OFETs exhibited a high average hole mobility of 1.1 cm^(2) V^(−1) s^(−1) and good device uniformity,indicating the applicability of CFEJ printing as a potential batch manufacturing and integration process for high-performance,scalable polymer nanowire-based OFET circuits.This technique can be used to fabricate various polymer arrays,enabling the use of organic polymer semiconductors in large-area,high-performance electronic devices and providing a new path for the fabrication of flexible displays and wearable electronics in the future.
