In this paper, we study the supercontractivity for Maxkov semigroups and obtain some sufficient and necessary conditions; especially explicit formulae are obtained for birth-death process and diffusion on the line. Su...In this paper, we study the supercontractivity for Maxkov semigroups and obtain some sufficient and necessary conditions; especially explicit formulae are obtained for birth-death process and diffusion on the line. Sufficient conditions and necessary conditions in terms of isoperimetric inequalities are also presented. Moreover, we prove that the supercontractivity is equivalent to the compact embedding of Sobolev space into an Orlicz space.展开更多
Dragline spider silks have relatively high mass-based mechanical properties (tensile strength, elongation to break and rupture energy) and are environmentally responsive (supercontraction). In order to produce new syn...Dragline spider silks have relatively high mass-based mechanical properties (tensile strength, elongation to break and rupture energy) and are environmentally responsive (supercontraction). In order to produce new synthetic fibers with these properties, many research groups have focused on identifying the chemical composition of these fibers and the structure of the fiber core. Since each fiber also has an outer skin, our study will provide a detailed understanding of the silk surface morphology, the response of the surface morphology to environmental conditions and processing variables, and also determine if the silk surface has a definitive patterning of charged amino acids. Specifically, by using force microscopy and functionalized nanoparticles, the present study examines 1) how the silk surface (topography, average roughness) is altered due to prior mechanical loading (viz. reeling speed), 2) alterations in morphology due to environmental conditions (supercontraction, storage time), and 3) the negatively and positively charged regions along with the surface using both force and nanoparticle mapping. Roughness data taken on dragline silk collected from Nephila clavipes spiders revealed that the surface comprised both smooth (5 nm RMS) and rough (65 nm RMS) regions. Supercontracted silk (from immersion in0.01 MPBS during AFM testing) showed higher surface roughness values compared to spider silk tested in the air, indicating that the surface might be reorganized during supercontraction. No correlation was found between surface roughness and neither collection speed nor aging time for the as-spun or supercontracted fiber, demonstrating the surface stability of the dragline silk over time in terms of roughness. Both the force microscopy and the nanoparticle methods suggested that the density of negatively charged amino acids (glutamic acid, aspartic acid) was higher than that of the positively charged amino acids (lysine, asparagine, and histidine).展开更多
Smart textiles are able to self-adapt to an irregular surface.So,they found new applications in intelligent clothes and equipments,where the properties and functionality of traditional polymeric fibers are insufficien...Smart textiles are able to self-adapt to an irregular surface.So,they found new applications in intelligent clothes and equipments,where the properties and functionality of traditional polymeric fibers are insufficient,and hard to be realized.Inspired by the supercontraction behavior of the spider silk,we prepared a spinnable hydrogel to form a sheath-core-like composite yarn,after being coated on cotton yarn.The strong hydrogen bonding between the cotton yarn and the polar groups of the hydrogel provides an outstanding mechanical stability,and the twists insertion forms a spiral-like architecture,which exhibited moisture-responsive super contraction behavior.By structural tailoring the chirality of the fiber twists and coiling extends into homo-chiral and heterochiral architectures,as displays contraction and expansion when is exposed to the moisture.Once the relative humidity is increased from 60 to 90%,a homochiral yarn exhibits 90%contraction,while a heterochiral yarn shows 450% expansion,and the maximum work capacity reached up to 6.1 J/Kg.The super contracted yarn can be re-stretched to its original length manifesting cyclability,which can be exploited to build a smart textile,selfadaptive to irregular surfaces.Such a strategy may be further extended to a wide variety of materials to achieve intelligent textiles from common fiber or yarns.展开更多
基金Research supported in part by RFDP(No 20010027007)973 ProjectNSFC(No 10121101,No 10025105 and No 10301007)
文摘In this paper, we study the supercontractivity for Maxkov semigroups and obtain some sufficient and necessary conditions; especially explicit formulae are obtained for birth-death process and diffusion on the line. Sufficient conditions and necessary conditions in terms of isoperimetric inequalities are also presented. Moreover, we prove that the supercontractivity is equivalent to the compact embedding of Sobolev space into an Orlicz space.
文摘Dragline spider silks have relatively high mass-based mechanical properties (tensile strength, elongation to break and rupture energy) and are environmentally responsive (supercontraction). In order to produce new synthetic fibers with these properties, many research groups have focused on identifying the chemical composition of these fibers and the structure of the fiber core. Since each fiber also has an outer skin, our study will provide a detailed understanding of the silk surface morphology, the response of the surface morphology to environmental conditions and processing variables, and also determine if the silk surface has a definitive patterning of charged amino acids. Specifically, by using force microscopy and functionalized nanoparticles, the present study examines 1) how the silk surface (topography, average roughness) is altered due to prior mechanical loading (viz. reeling speed), 2) alterations in morphology due to environmental conditions (supercontraction, storage time), and 3) the negatively and positively charged regions along with the surface using both force and nanoparticle mapping. Roughness data taken on dragline silk collected from Nephila clavipes spiders revealed that the surface comprised both smooth (5 nm RMS) and rough (65 nm RMS) regions. Supercontracted silk (from immersion in0.01 MPBS during AFM testing) showed higher surface roughness values compared to spider silk tested in the air, indicating that the surface might be reorganized during supercontraction. No correlation was found between surface roughness and neither collection speed nor aging time for the as-spun or supercontracted fiber, demonstrating the surface stability of the dragline silk over time in terms of roughness. Both the force microscopy and the nanoparticle methods suggested that the density of negatively charged amino acids (glutamic acid, aspartic acid) was higher than that of the positively charged amino acids (lysine, asparagine, and histidine).
基金This work was supported by the National Key Research and Development Program of China(Grant#2019YFE0119600)the National Natural Science Foundation of China(Grants 51973093,U1533122,and 51773094)+5 种基金“Frontiers Science Center for New Organic Matter”,Nankai University,Tianjin,China(Grant#63181206)the Science Foundation for Distinguished Young Scholars of Tianjin(Grant#18JCJQJC46600)the Xingliao Talent Plan(XLYC1802042)Key Laboratory of Display Materials and Photoelectric Devices,Ministry of Education(LX20200420001)the Fundamental Research Funds for the Central Universities(Grant#63171219)National Special Support Plan for High-level Talents people(C041800902).
文摘Smart textiles are able to self-adapt to an irregular surface.So,they found new applications in intelligent clothes and equipments,where the properties and functionality of traditional polymeric fibers are insufficient,and hard to be realized.Inspired by the supercontraction behavior of the spider silk,we prepared a spinnable hydrogel to form a sheath-core-like composite yarn,after being coated on cotton yarn.The strong hydrogen bonding between the cotton yarn and the polar groups of the hydrogel provides an outstanding mechanical stability,and the twists insertion forms a spiral-like architecture,which exhibited moisture-responsive super contraction behavior.By structural tailoring the chirality of the fiber twists and coiling extends into homo-chiral and heterochiral architectures,as displays contraction and expansion when is exposed to the moisture.Once the relative humidity is increased from 60 to 90%,a homochiral yarn exhibits 90%contraction,while a heterochiral yarn shows 450% expansion,and the maximum work capacity reached up to 6.1 J/Kg.The super contracted yarn can be re-stretched to its original length manifesting cyclability,which can be exploited to build a smart textile,selfadaptive to irregular surfaces.Such a strategy may be further extended to a wide variety of materials to achieve intelligent textiles from common fiber or yarns.
