Carbon-based metal-free catalysts are a promising substitute for the rare and expensive platinum （Pt） used in the oxygen reduction reaction. We herein report N-doped graphene （NG） that is exquisitely integrated in...Carbon-based metal-free catalysts are a promising substitute for the rare and expensive platinum （Pt） used in the oxygen reduction reaction. We herein report N-doped graphene （NG） that is exquisitely integrated into highly conductive frameworks, simultaneously providing more active sites and higher conductivity. The NG was in situ grown on carbon fibers derived from silk cocoon （SCCf） using a simple one-step thermal treatment. The resulting product （NG-SCCf）, possessing a meso-/macroporous structure with three-dimensional （3D） interconnected networks, exhibits an onset potential that is only 0.1 V less negative than that of Pt/C and shows stability and methanol tolerance superior to those of Pt/C in alkaline media. Moreover, in the absence of Pt as co-catalyst, NG-SCCf shows a photocatalytic H2 production rate of 66.0 ~tmol-h l.g 1, 4.4-fold higher than that of SCCf. This outstanding activity is intimately related to the in situ grown NG, hierarchically porous structure, and 3D interconnected networks, which not only introduce more active sites but also enable smooth electron transfer, mass transport, and effective separation of electron-hole pairs. Considering the abundance of the green raw material in combination with easy and low-cost preparation, this work contributes to the development of advanced sustainable catalysts in energy storage/conversion fields, such as electro- and photocatalysis.展开更多
Most animals have the ability to adapt, to some extends and in different ways, the variation or disturbance of environment. In our experiments, we forced a silkworm caterpillar to spin two, three or four thin cocoons ...Most animals have the ability to adapt, to some extends and in different ways, the variation or disturbance of environment. In our experiments, we forced a silkworm caterpillar to spin two, three or four thin cocoons by taking it out from the cocoon being constructed. The mechanical properties of these cocoons were studied by static tensile tests and dynamic mechanical thermal analysis. Though external disturbances may cause the decrease in the total weight of silk spun by the silkworm, a gradual enhancement was interestingly found in the mechanical properties of these thin cocoons. Scanning electron microscopy observations of the fractured specimens of the cocoons showed that there exist several different energy dissipation mechanisms occurred simultaneously at macro-, meso-, and micro-scales, yielding a superior capacity of cocoons to adsorb the energy of possible attacks from the outside and to protect efficiently its pupa against damage. Through evolution of millions of years, therefore, the silkworm Bombyx mori seems to have gained the ability to adapt external disturbances and to redesign a new cocoon with optimized protective function when its first cocoon has been damaged for some reasons.展开更多
In the context of the Belt and Road Initiative,it is of great significance to study the trade ties between China and Southeast Asia with cocoon silk as a link.Trend analysis,trade competitiveness index and trade compl...In the context of the Belt and Road Initiative,it is of great significance to study the trade ties between China and Southeast Asia with cocoon silk as a link.Trend analysis,trade competitiveness index and trade complementarity index were comprehensively used in this paper to study the competitiveness and complementarity of the cocoon silk trade between China and Southeast Asia.The results show that the export trade volume of cocoon silk of China and Southeast Asia is decreasing while fluctuating,but it is difficult for other regions to replace their export trade status in the world market.The development trend of the replacement of the silkworm cocoon trade by the raw silk trade is presented.The cocoon silk trade of China and Southeast Asia is characterized by dislocation competition.China's raw silk export trade is competitive and has become the leader of the raw silk export camp.This paper further analyzes the changes and complementarities of the cocoon silk trade competitiveness between China and Southeast Asia.展开更多
Back to 1994, a transient price hike of cocoon silk eventually led to a predicament for Chinese silk industry in the following years. A decade later, is that slump going to happen again?
The breeding activities aimed to create a natural green cocoon variety for spring rearing with the characteristics of stable natural cocoon color,easy rearing and good silk quality.Four different lines from the excell...The breeding activities aimed to create a natural green cocoon variety for spring rearing with the characteristics of stable natural cocoon color,easy rearing and good silk quality.Four different lines from the excellent silkworm variety Jingsong×Haoyue were taken as recurrent parents,using the natural green cocoon variety G 9202 as donor parent.After other excellent parents were introduced to cross with these different lines,four new breeding materials were selected by recurrent backcross breeding.The characters of these breeding materials showed not only natural green cocoon but also excellent comprehensive traits.A naturally colored cocoon quaternary hybrid with excellent practical characters was selected based on multiple hybrids.It is suitable for spring rearing in Yangtze valley which includes Hunan Province.It was approved by Hunan Provincial Crop Variety Approval Committee and designated Xiangcailu No.1 in 2016.展开更多
基金The work was financially supported by National Natural Science Foundation of China （Nos. 51203182 and 51173202）, Foundation for the Author of Excellent Doctoral Dissertation of Hunan Province （No. YB2014B004）, Aeronautical Science Foundation of China （No. 20143188004）, Key Laboratory of Advanced Textile Materials and Manufacturing Technology （Zhejiang Sci-Tech University）, Ministry of Education （No. 2015001）, Key Laboratory of Lightweight and Reliability Technology for Engineering Vehicle, College of Hunan Province （No. 2016kfjj01）, Research Project of NUDT. We thank Tengyuan Wang for help in ORR experiment and helpful discussions.
文摘Carbon-based metal-free catalysts are a promising substitute for the rare and expensive platinum （Pt） used in the oxygen reduction reaction. We herein report N-doped graphene （NG） that is exquisitely integrated into highly conductive frameworks, simultaneously providing more active sites and higher conductivity. The NG was in situ grown on carbon fibers derived from silk cocoon （SCCf） using a simple one-step thermal treatment. The resulting product （NG-SCCf）, possessing a meso-/macroporous structure with three-dimensional （3D） interconnected networks, exhibits an onset potential that is only 0.1 V less negative than that of Pt/C and shows stability and methanol tolerance superior to those of Pt/C in alkaline media. Moreover, in the absence of Pt as co-catalyst, NG-SCCf shows a photocatalytic H2 production rate of 66.0 ~tmol-h l.g 1, 4.4-fold higher than that of SCCf. This outstanding activity is intimately related to the in situ grown NG, hierarchically porous structure, and 3D interconnected networks, which not only introduce more active sites but also enable smooth electron transfer, mass transport, and effective separation of electron-hole pairs. Considering the abundance of the green raw material in combination with easy and low-cost preparation, this work contributes to the development of advanced sustainable catalysts in energy storage/conversion fields, such as electro- and photocatalysis.
基金the National Natural Science Foundation of China (10402017,10732050,10525210,10121202)
文摘Most animals have the ability to adapt, to some extends and in different ways, the variation or disturbance of environment. In our experiments, we forced a silkworm caterpillar to spin two, three or four thin cocoons by taking it out from the cocoon being constructed. The mechanical properties of these cocoons were studied by static tensile tests and dynamic mechanical thermal analysis. Though external disturbances may cause the decrease in the total weight of silk spun by the silkworm, a gradual enhancement was interestingly found in the mechanical properties of these thin cocoons. Scanning electron microscopy observations of the fractured specimens of the cocoons showed that there exist several different energy dissipation mechanisms occurred simultaneously at macro-, meso-, and micro-scales, yielding a superior capacity of cocoons to adsorb the energy of possible attacks from the outside and to protect efficiently its pupa against damage. Through evolution of millions of years, therefore, the silkworm Bombyx mori seems to have gained the ability to adapt external disturbances and to redesign a new cocoon with optimized protective function when its first cocoon has been damaged for some reasons.
基金Scientific Research and Innovation Team Construction Project for Colleges and Universities of Sichuan Province(14TD0039).
文摘In the context of the Belt and Road Initiative,it is of great significance to study the trade ties between China and Southeast Asia with cocoon silk as a link.Trend analysis,trade competitiveness index and trade complementarity index were comprehensively used in this paper to study the competitiveness and complementarity of the cocoon silk trade between China and Southeast Asia.The results show that the export trade volume of cocoon silk of China and Southeast Asia is decreasing while fluctuating,but it is difficult for other regions to replace their export trade status in the world market.The development trend of the replacement of the silkworm cocoon trade by the raw silk trade is presented.The cocoon silk trade of China and Southeast Asia is characterized by dislocation competition.China's raw silk export trade is competitive and has become the leader of the raw silk export camp.This paper further analyzes the changes and complementarities of the cocoon silk trade competitiveness between China and Southeast Asia.
文摘Back to 1994, a transient price hike of cocoon silk eventually led to a predicament for Chinese silk industry in the following years. A decade later, is that slump going to happen again?
基金Supported by Earmarked Fund for China Agriculture Research System(CARS-18)Hunan Provincial Science and Technology Support Program(2013NK3071)+1 种基金Natural Science Foundation of Hunan Province(2017JJ2137)Silkworm Germplasm Resources Multi-element Application Research and Development Innovation Team(2017XC01)
文摘The breeding activities aimed to create a natural green cocoon variety for spring rearing with the characteristics of stable natural cocoon color,easy rearing and good silk quality.Four different lines from the excellent silkworm variety Jingsong×Haoyue were taken as recurrent parents,using the natural green cocoon variety G 9202 as donor parent.After other excellent parents were introduced to cross with these different lines,four new breeding materials were selected by recurrent backcross breeding.The characters of these breeding materials showed not only natural green cocoon but also excellent comprehensive traits.A naturally colored cocoon quaternary hybrid with excellent practical characters was selected based on multiple hybrids.It is suitable for spring rearing in Yangtze valley which includes Hunan Province.It was approved by Hunan Provincial Crop Variety Approval Committee and designated Xiangcailu No.1 in 2016.
