A material-structure integrated design method is proposed in this paper,with which micropillar and microwedge arrayed surfaces are fabricated based on a novel nanoparticlereinforced silicone rubber composite(NRSRC)wit...A material-structure integrated design method is proposed in this paper,with which micropillar and microwedge arrayed surfaces are fabricated based on a novel nanoparticlereinforced silicone rubber composite(NRSRC)with high mechanical strength and strong surface adhesion.It is found that the micropillar-arrayed surface and the microwedgearrayed surface show a normal adhesive strength of 50.9 kPa and a shear adhesive strength of 137.3 kPa,respectively,which are much higher than those of previously reported adhesive surfaces made by pure soft polymers.Furthermore,the micro-wedgearrayed surface shows not only strong and stable adhe-sion on rough and smooth substrates but also an obvious anisotropy in the adhesion property.The latter consequently leads to an easy control of the attachment/detachment switch,which is evidenced by a mechanical gripper with a microwedged surface.Therefore,firmly picking up and easily releasing a heavy glass plate can be realized.All these results demonstrate the apparent advantages of the present compo-sitebased fibrillar surfaces in achieving reliable and reversible adhesion and should have promising applications for manufac-turing advanced adhesive devices,such as mechanical fixtures,portable climbing equipment and space robots.展开更多
Amyloid beta-peptides(Aβ) are known to undergo active transport across the blood-brain barrier, and cerebral amyloid angiopathy has been shown to be a prominent feature in the majority of Alzheimer's disease. Que...Amyloid beta-peptides(Aβ) are known to undergo active transport across the blood-brain barrier, and cerebral amyloid angiopathy has been shown to be a prominent feature in the majority of Alzheimer's disease. Quercetin is a natural flavonoid molecule and has been demonstrated to have potent neuroprotective effects, but its protective effect on endothelial cells under Aβ-damaged condition is unclear. In the present study, the protective effects of quercetin on brain microvascular endothelial cells injured by fibrillar Aβ_(1–40)(f Aβ_(1–40)) were observed. The results show that f Aβ_(1–40)-induced cytotoxicity in human brain microvascular endothelial cells(h BMECs) can be relieved by quercetin treatment. Quercetin increases cell viability, reduces the release of lactate dehydrogenase, and relieves nuclear condensation.Quercetin also alleviates intracellular reactive oxygen species generation and increases superoxide dismutase activity. Moreover, it strengthens the barrier integrity through the preservation of the transendothelial electrical resistance value, the relief of aggravated permeability, and the increase of characteristic enzyme levels after being exposed to f Aβ_(1–40). In conclusion, quercetin protects h BMECs from f Aβ_(1–40)-induced toxicity.展开更多
Strong preshear flow stretches poly(butene-1)chains to form flow-induced precursors of fibrillar crystals.The formation leads to further growth of shear/normal stress after the stress reaches the steady state.In this ...Strong preshear flow stretches poly(butene-1)chains to form flow-induced precursors of fibrillar crystals.The formation leads to further growth of shear/normal stress after the stress reaches the steady state.In this study,stress relaxation measurements are performed after intervals of a strong flow during which the precursors form.The small-angle X-ray scattering(SAXS)and wide-angle X-ray diffraction(WAXD)measurements are conducted to characterize the crystalline structure formed after the preshear and relaxation processes,each of different periods.A combination of the stress relaxation and scattering results reveal that for the precursors formed within 5 s,the stress can fully relax and the orientation of the subsequent crystals(formed upon quenching the sample at different stress levels)decays gradually with the relaxation.In comparison,for those precursors formed after 5 s,the stress hardly relaxes during~10^(4) s,and the orientation of the subsequent crystals hardly decays,suggesting that the precursors have been somehow stabilized during the shear.These features have been discussed with respect to the percolation of the precursors to form a reversible network.展开更多
The dispersion and filler network of fibrillar silicate（FS） in elastomers were studied. The results showed that a good dispersion of FS in matrix during mechanical blending in unvulcanized composites contributed to ...The dispersion and filler network of fibrillar silicate（FS） in elastomers were studied. The results showed that a good dispersion of FS in matrix during mechanical blending in unvulcanized composites contributed to a strong FS filler network, different from that of traditional reinforcing fillers. Meanwhile, the filler re-aggregation during vulcanization caused by the overlapping and intertwining of FS further strengthened the filler network. The factors including Mooney viscosity and molecular polarity of elastomer, type and amount of silane coupling agents used for filler modification, that may influence the filler network, were studied. Our study helps us to understand the mechanism for the formation of filler network of FS in elastomers and provides guidance for the preparation of high performance FS/elastomer composites.展开更多
Minor fibrillar collagen types V and XI,are those less abundant than the fibrillar collagen types I,II and III.The alpha chains share a high degree of similarity with respect to protein sequence in all domains except ...Minor fibrillar collagen types V and XI,are those less abundant than the fibrillar collagen types I,II and III.The alpha chains share a high degree of similarity with respect to protein sequence in all domains except the variable region.Genomic variation and,in some cases,extensive alternative splicing contribute to the unique sequence characteristics of the variable region.While unique expression patterns in tissues exist,the functions and biological relevance of the variable regions have not been elucidated.In this review,we summarize the existing knowledge about expression patterns and biological functions of the collagen types V and XI alpha chains.Analysis of biochemical similarities among the peptides encoded by each exon of the variable region suggests the potential for a shared function.The alternative splicing,conservation of biochemical characteristics in light of low sequence conservation,and evidence for intrinsic disorder,suggest modulation of binding events between the surface of collagen fibrils and surrounding extracellular molecules as a shared function.展开更多
Nucleic acids with G4 elements play a role in the formation of aggregates involved in intracellular phase transitions.Our previous studies suggest that different forms of DNA could act as an accelerating template in C...Nucleic acids with G4 elements play a role in the formation of aggregates involved in intracellular phase transitions.Our previous studies suggest that different forms of DNA could act as an accelerating template in Cu/Zn superoxide dismutase(SOD1)aggregation.Here,we examined the regulation of fo rmation and cytotoxicity of the SOD1 aggregates by single-stranded 12-merdeoxynucleotide oligomers(dN)_(12)(N=A,T,G,C;ssDNAs)under acidic conditions.The ssDNAs can be divided into two groups based on their roles in SOD1 binding,exposure of hydrophobic clusters in SOD1,accelerated formation,morphology and cytotoxicity of SOD1 aggregates.G-quadruplexes convert SOD1 into fibrillar aggregates as a template,a fact which was observed for the first time in the nucleic acid regulation of protein aggregation.Moreover,the fibrillar or fibril-like SOD1 species with a G-quadruplex provided by(dG)_(12)were less toxic than the amorphous species with(dN)_(12)(N=A,T).This study not only indicates that both morphology and cytotoxicity of protein aggregates can be regulated by the protein-bound DNAs,but also help us understand roles of nucleic aid G-quadruplexes in the formation of aggregates and membrane less organelles involved in intracellular phase transitions.展开更多
Motivated by the recent biomimic design of microstructured adhesive surfaces,we study adhesion between a film-terminated fibrillar array and a rigid substrate.Using a two-dimensional model and ignoring the deformation...Motivated by the recent biomimic design of microstructured adhesive surfaces,we study adhesion between a film-terminated fibrillar array and a rigid substrate.Using a two-dimensional model and ignoring the deformation of the fibers and the backing layer,we show that the adhesion behavior is dominated by a dimensionless parameter reflecting the global flexibility of the terminal film.In particular,if the parameter is larger than 0.4,the adhesion is reversible;otherwise one or more hysteresis loops will appear after an approach-retraction cycle,leading to significant increase in the specific separation work.The result is expected to help not only optimal design of the structure,but also other applications such as micro-manipulation in micromechanical systems.展开更多
基金NSFC through Grants(No.12032004,No.12293000,No.12293002,No.12272043)Natural Science Foundation of Henan(No.202300410088)as well as Innovation Demonstration Project of Henan(No.201111211400).
文摘A material-structure integrated design method is proposed in this paper,with which micropillar and microwedge arrayed surfaces are fabricated based on a novel nanoparticlereinforced silicone rubber composite(NRSRC)with high mechanical strength and strong surface adhesion.It is found that the micropillar-arrayed surface and the microwedgearrayed surface show a normal adhesive strength of 50.9 kPa and a shear adhesive strength of 137.3 kPa,respectively,which are much higher than those of previously reported adhesive surfaces made by pure soft polymers.Furthermore,the micro-wedgearrayed surface shows not only strong and stable adhe-sion on rough and smooth substrates but also an obvious anisotropy in the adhesion property.The latter consequently leads to an easy control of the attachment/detachment switch,which is evidenced by a mechanical gripper with a microwedged surface.Therefore,firmly picking up and easily releasing a heavy glass plate can be realized.All these results demonstrate the apparent advantages of the present compo-sitebased fibrillar surfaces in achieving reliable and reversible adhesion and should have promising applications for manufac-turing advanced adhesive devices,such as mechanical fixtures,portable climbing equipment and space robots.
基金supported by the National Natural Science Foundation of China (Nos. 81373388, 81473374 and 81102830)
文摘Amyloid beta-peptides(Aβ) are known to undergo active transport across the blood-brain barrier, and cerebral amyloid angiopathy has been shown to be a prominent feature in the majority of Alzheimer's disease. Quercetin is a natural flavonoid molecule and has been demonstrated to have potent neuroprotective effects, but its protective effect on endothelial cells under Aβ-damaged condition is unclear. In the present study, the protective effects of quercetin on brain microvascular endothelial cells injured by fibrillar Aβ_(1–40)(f Aβ_(1–40)) were observed. The results show that f Aβ_(1–40)-induced cytotoxicity in human brain microvascular endothelial cells(h BMECs) can be relieved by quercetin treatment. Quercetin increases cell viability, reduces the release of lactate dehydrogenase, and relieves nuclear condensation.Quercetin also alleviates intracellular reactive oxygen species generation and increases superoxide dismutase activity. Moreover, it strengthens the barrier integrity through the preservation of the transendothelial electrical resistance value, the relief of aggravated permeability, and the increase of characteristic enzyme levels after being exposed to f Aβ_(1–40). In conclusion, quercetin protects h BMECs from f Aβ_(1–40)-induced toxicity.
基金financially supported by the National Natural Science Foundation of China(No.21790343).
文摘Strong preshear flow stretches poly(butene-1)chains to form flow-induced precursors of fibrillar crystals.The formation leads to further growth of shear/normal stress after the stress reaches the steady state.In this study,stress relaxation measurements are performed after intervals of a strong flow during which the precursors form.The small-angle X-ray scattering(SAXS)and wide-angle X-ray diffraction(WAXD)measurements are conducted to characterize the crystalline structure formed after the preshear and relaxation processes,each of different periods.A combination of the stress relaxation and scattering results reveal that for the precursors formed within 5 s,the stress can fully relax and the orientation of the subsequent crystals(formed upon quenching the sample at different stress levels)decays gradually with the relaxation.In comparison,for those precursors formed after 5 s,the stress hardly relaxes during~10^(4) s,and the orientation of the subsequent crystals hardly decays,suggesting that the precursors have been somehow stabilized during the shear.These features have been discussed with respect to the percolation of the precursors to form a reversible network.
基金financially supported by the National Science Fund for Distinguished Young Scholars of China(No.51525301)the National Natural Science Foundation of China(No.51373012)the National Basic Research Program of China(No.2015CB654704)
文摘The dispersion and filler network of fibrillar silicate（FS） in elastomers were studied. The results showed that a good dispersion of FS in matrix during mechanical blending in unvulcanized composites contributed to a strong FS filler network, different from that of traditional reinforcing fillers. Meanwhile, the filler re-aggregation during vulcanization caused by the overlapping and intertwining of FS further strengthened the filler network. The factors including Mooney viscosity and molecular polarity of elastomer, type and amount of silane coupling agents used for filler modification, that may influence the filler network, were studied. Our study helps us to understand the mechanism for the formation of filler network of FS in elastomers and provides guidance for the preparation of high performance FS/elastomer composites.
基金supported in part by the Arthritis Foundation,the NIH/NIAMS Grants(No.RO1AR47985 and KO2AR48672)NIH/NCRR Grant(No.P20RR16454)+3 种基金NIH/NIGMS Grant(No.P20 GM103408)NIH/NICHD Grant(No.R15HD059949)the National Science Foundation(Grant No.0619793,0923535)M.J.Murdock Foundation,Idaho State Board of Education Higher Education Research Council,Lori and Duane Stueckle,and St.Luke’s Regional Medical Center。
文摘Minor fibrillar collagen types V and XI,are those less abundant than the fibrillar collagen types I,II and III.The alpha chains share a high degree of similarity with respect to protein sequence in all domains except the variable region.Genomic variation and,in some cases,extensive alternative splicing contribute to the unique sequence characteristics of the variable region.While unique expression patterns in tissues exist,the functions and biological relevance of the variable regions have not been elucidated.In this review,we summarize the existing knowledge about expression patterns and biological functions of the collagen types V and XI alpha chains.Analysis of biochemical similarities among the peptides encoded by each exon of the variable region suggests the potential for a shared function.The alternative splicing,conservation of biochemical characteristics in light of low sequence conservation,and evidence for intrinsic disorder,suggest modulation of binding events between the surface of collagen fibrils and surrounding extracellular molecules as a shared function.
基金financially supported by the National Natural Science Foundation of China(Nos.21771073,22077046,21001047,21072074)the Fundamental Research Funds for the Central Universities(No.CCNU19TS052)。
文摘Nucleic acids with G4 elements play a role in the formation of aggregates involved in intracellular phase transitions.Our previous studies suggest that different forms of DNA could act as an accelerating template in Cu/Zn superoxide dismutase(SOD1)aggregation.Here,we examined the regulation of fo rmation and cytotoxicity of the SOD1 aggregates by single-stranded 12-merdeoxynucleotide oligomers(dN)_(12)(N=A,T,G,C;ssDNAs)under acidic conditions.The ssDNAs can be divided into two groups based on their roles in SOD1 binding,exposure of hydrophobic clusters in SOD1,accelerated formation,morphology and cytotoxicity of SOD1 aggregates.G-quadruplexes convert SOD1 into fibrillar aggregates as a template,a fact which was observed for the first time in the nucleic acid regulation of protein aggregation.Moreover,the fibrillar or fibril-like SOD1 species with a G-quadruplex provided by(dG)_(12)were less toxic than the amorphous species with(dN)_(12)(N=A,T).This study not only indicates that both morphology and cytotoxicity of protein aggregates can be regulated by the protein-bound DNAs,but also help us understand roles of nucleic aid G-quadruplexes in the formation of aggregates and membrane less organelles involved in intracellular phase transitions.
基金supported by the National Basic Research Program of China (Grant No. 2011CB302101)PhD Programs Foundation of the Ministry of Education of China (Grant No. 20113402110005)
文摘Motivated by the recent biomimic design of microstructured adhesive surfaces,we study adhesion between a film-terminated fibrillar array and a rigid substrate.Using a two-dimensional model and ignoring the deformation of the fibers and the backing layer,we show that the adhesion behavior is dominated by a dimensionless parameter reflecting the global flexibility of the terminal film.In particular,if the parameter is larger than 0.4,the adhesion is reversible;otherwise one or more hysteresis loops will appear after an approach-retraction cycle,leading to significant increase in the specific separation work.The result is expected to help not only optimal design of the structure,but also other applications such as micro-manipulation in micromechanical systems.
