This study aims to reveal the mechanism that how the content of steel fibers and strength grades affect the macro performance of the ultra-high performance fiber reinforced cementitious composite （UHPFRCC） and to st...This study aims to reveal the mechanism that how the content of steel fibers and strength grades affect the macro performance of the ultra-high performance fiber reinforced cementitious composite （UHPFRCC） and to study the UHPFRCC durability under the combined effect of loads and environments. Three types of high and ultra-high performance fiber reinforced cement composites with different strength grades （100, 150, 200 MPa） and different steel fiber volume fractions （0%, 1%, 2%, 3%） are prepared. The main properties of mechanical performance and short-term durability are studied. A preloading frame is designed to apply a four- point load external flexural stress with a stress selection ratio of 0.5 for UHPFRCC150 specimens. The results show that the growth in strength grade with a proper content of steel fiber greatly increases the strength and toughness of the HPFRCC and the UHPFRCC while decreasing the dry-shrinkage ratio. For the loaded specimens, the existence of steel fiber can reduce the negative influence of tensile stress on the Cl- penetration resistance of the UHPFRCC in addition to improving its ability to resist the freeze-thaw damage.展开更多
The high oxidation ability of manganese oxides or soils was used to study effects of pH and coatingon Cr(Ⅲ) oxidation. The results indicated that Cr(Ⅲ) oxidation peaked in pH 4.0-6.5. The amount andrate of Cr(Ⅲ) be...The high oxidation ability of manganese oxides or soils was used to study effects of pH and coatingon Cr(Ⅲ) oxidation. The results indicated that Cr(Ⅲ) oxidation peaked in pH 4.0-6.5. The amount andrate of Cr(Ⅲ) being oxidized by uncoated δ-MnO2 were larger than those by Fe oxide- or CaCO3-coatedone. Inorganic Cr(Ⅲ) was more easi1y oxidized by MnO2 than organic complex Cr(Ⅲ) due to differentsurface affinities. Precipitated Cr(Ⅲ) and adsorbed Cr(Ⅲ) might be transferred onto MnO2 surface andthen oxidized to Cr(VI).展开更多
Based on 3D Biot’s consolidation theory and nonlinear Duncan-Chang’s model, a 3D FEM (finite element method) program is developed considering the coupling of groundwater seepage and soil skeleton deformation during ...Based on 3D Biot’s consolidation theory and nonlinear Duncan-Chang’s model, a 3D FEM (finite element method) program is developed considering the coupling of groundwater seepage and soil skeleton deformation during excavation. The comparison between the analysis result considering the variation of water head difference and that without considering it shows that the porewater pressure distribution of the former is distinctly different from that of the latter and that the foundation pit de- formations of the former are larger than those of the latter, so that the result without considering the variation of water head dif- ference is unreliable. The distribution rules of soil horizontal and vertical displacements around the pit and excess porewater pressure are analyzed in detail in time and space, which is very significant for guiding underground engineering construction and ensuring environment safety around the pit.展开更多
Inbreeding negatively affects various life-history traits, with inbred individuals typically having lower fit- ness than outbred individuals （=inbreeding depression）. Inbreeding depression is often emphasized under ...Inbreeding negatively affects various life-history traits, with inbred individuals typically having lower fit- ness than outbred individuals （=inbreeding depression）. Inbreeding depression is often emphasized under environmental stress, but the underlying mechanisms and potential long-lasting consequences of such inbreeding-environment interactions remain poorly understood. Here, we hypothesize that inbreeding-environment interactions that occur early in life have long-term physiological effects, in partic- ular on the adult oxidative balance. We applied a unique experimental design to manipulate early life conditions of inbred and outbred songbirds （Serinus canaria） that allowed us to separate prenatal and postnatal components of early life conditions and their respective importance in inbreeding-environment interactions. We measured a wide variety of markers of oxidative status in adulthood, resulting in a com- prehensive account for oxidative balance. Using a Bayesian approach with Markov chain Monte Carlo, we found clear sex-specific effects and we also found only in females small yet significant long-term effects of inbreeding-environment interactions on adult oxidative balance. Postnatal components of early life conditions were most persuasively reflected on adult oxidative balance, with inbred females that experienced disadvantageous postnatal conditions upregulating enzymatic antioxidants in adulthood. Our study provides some evidence that adult oxidative balance can reflect inbreeding-environment inter- actions early in life, but given the rather small effects that were limited to females, we conclude that oxida- tive stress miaht have a limited role as mechanism underlvina inhre.e.dina-envirnnme.nt inte.raetinn.q_展开更多
Poly(p-phenylene-2,6-benzobisoxazole)nanofiber(PNF)paper is facing unprecedented challenges in enhancing the interaction between the PNFs and improving its hydrophobicity.In this work,a sol–gel film transformation ap...Poly(p-phenylene-2,6-benzobisoxazole)nanofiber(PNF)paper is facing unprecedented challenges in enhancing the interaction between the PNFs and improving its hydrophobicity.In this work,a sol–gel film transformation approach was developed to fabricate high-strength PNF paper.Iron ions formed coordination bonds between PNFs to obtain a preforming three-dimensional,interconnective nanofiber network.Subsequently,polytetrafluoroethylene(PTFE)particles were sprayed onto the surface of the paper,followed by thermal treatment to obtain double-layered PTFE-P/PNF nanocomposite paper.The nanocomposite paper presents incredible tensile strength(271.6 MPa,increased by 52.9%),folding endurance,super-hydrophobicity,and self-cleaning performances.Moreover,it exhibits low dielectric constant(2.06)and dielectric loss tangent(0.0133)values.According to the wave-transparent model for a doublelayered dielectric established by Maxwell’s equations,the wave-transparent coefficients of electromagnetic waves incident from both sides of the paper are 97.6%(PNF side)and 96.0%(PTFE/P(S-co-BCB-coMMA)side),respectively.The PTFE-P/PNF nanocomposite paper possesses great potential in the fields of wave-transparent applications.展开更多
We have investigated the dynamics of a protomer coupled to two different decoherent environments,each in a configuration called the spin star configuration.Using the quantum mechanics method,in different situations,we...We have investigated the dynamics of a protomer coupled to two different decoherent environments,each in a configuration called the spin star configuration.Using the quantum mechanics method,in different situations,we obtain the analytical expressions for the transition probability in the protomer system.In thermal equilibrium,there exist well-defined ranges of parameters for which decoherent interaction between the protomer and the environment assists energy transfer in the protomer system,while in pure quantum mechanics states,the decoherent interaction assists energy transfer for an eigenstate but against energy transfer for quantum mechanics averages.In particular,we also find that the dimerization of two bacteriochlorophylls in protomer can always assist energy transfer in certain parameter range,and in the appropriate spin bath energy,the efficiency of energy transport is sensitively depended on the temperature of environments.展开更多
基金The Technical Research Program from NV Bekaert SA of Belgium (No. 8612000003)the National Natural Science Foundation of China (No. 50908047)
文摘This study aims to reveal the mechanism that how the content of steel fibers and strength grades affect the macro performance of the ultra-high performance fiber reinforced cementitious composite （UHPFRCC） and to study the UHPFRCC durability under the combined effect of loads and environments. Three types of high and ultra-high performance fiber reinforced cement composites with different strength grades （100, 150, 200 MPa） and different steel fiber volume fractions （0%, 1%, 2%, 3%） are prepared. The main properties of mechanical performance and short-term durability are studied. A preloading frame is designed to apply a four- point load external flexural stress with a stress selection ratio of 0.5 for UHPFRCC150 specimens. The results show that the growth in strength grade with a proper content of steel fiber greatly increases the strength and toughness of the HPFRCC and the UHPFRCC while decreasing the dry-shrinkage ratio. For the loaded specimens, the existence of steel fiber can reduce the negative influence of tensile stress on the Cl- penetration resistance of the UHPFRCC in addition to improving its ability to resist the freeze-thaw damage.
文摘The high oxidation ability of manganese oxides or soils was used to study effects of pH and coatingon Cr(Ⅲ) oxidation. The results indicated that Cr(Ⅲ) oxidation peaked in pH 4.0-6.5. The amount andrate of Cr(Ⅲ) being oxidized by uncoated δ-MnO2 were larger than those by Fe oxide- or CaCO3-coatedone. Inorganic Cr(Ⅲ) was more easi1y oxidized by MnO2 than organic complex Cr(Ⅲ) due to differentsurface affinities. Precipitated Cr(Ⅲ) and adsorbed Cr(Ⅲ) might be transferred onto MnO2 surface andthen oxidized to Cr(VI).
基金Project supported by the China Postdoctoral Science Foundation (No. 20060400672)Innovation Fund of Shanghai University, China
文摘Based on 3D Biot’s consolidation theory and nonlinear Duncan-Chang’s model, a 3D FEM (finite element method) program is developed considering the coupling of groundwater seepage and soil skeleton deformation during excavation. The comparison between the analysis result considering the variation of water head difference and that without considering it shows that the porewater pressure distribution of the former is distinctly different from that of the latter and that the foundation pit de- formations of the former are larger than those of the latter, so that the result without considering the variation of water head dif- ference is unreliable. The distribution rules of soil horizontal and vertical displacements around the pit and excess porewater pressure are analyzed in detail in time and space, which is very significant for guiding underground engineering construction and ensuring environment safety around the pit.
文摘Inbreeding negatively affects various life-history traits, with inbred individuals typically having lower fit- ness than outbred individuals （=inbreeding depression）. Inbreeding depression is often emphasized under environmental stress, but the underlying mechanisms and potential long-lasting consequences of such inbreeding-environment interactions remain poorly understood. Here, we hypothesize that inbreeding-environment interactions that occur early in life have long-term physiological effects, in partic- ular on the adult oxidative balance. We applied a unique experimental design to manipulate early life conditions of inbred and outbred songbirds （Serinus canaria） that allowed us to separate prenatal and postnatal components of early life conditions and their respective importance in inbreeding-environment interactions. We measured a wide variety of markers of oxidative status in adulthood, resulting in a com- prehensive account for oxidative balance. Using a Bayesian approach with Markov chain Monte Carlo, we found clear sex-specific effects and we also found only in females small yet significant long-term effects of inbreeding-environment interactions on adult oxidative balance. Postnatal components of early life conditions were most persuasively reflected on adult oxidative balance, with inbred females that experienced disadvantageous postnatal conditions upregulating enzymatic antioxidants in adulthood. Our study provides some evidence that adult oxidative balance can reflect inbreeding-environment inter- actions early in life, but given the rather small effects that were limited to females, we conclude that oxida- tive stress miaht have a limited role as mechanism underlvina inhre.e.dina-envirnnme.nt inte.raetinn.q_
基金supported by the National Scientific Research Project(Basis Strengthening Plan)China Postdoctoral Science Foundation(2019M653735)+2 种基金State Key Laboratory of Solidification Processing at the Northwestern Polytechnical University(NPU)(SKLSP202103)the Innovation Foundation for Doctor’s Dissertations of NPU(CX2021036)financially supported by the Polymer Electromagnetic Functional Materials Innovation Team of Shaanxi Sanqin Scholars。
文摘Poly(p-phenylene-2,6-benzobisoxazole)nanofiber(PNF)paper is facing unprecedented challenges in enhancing the interaction between the PNFs and improving its hydrophobicity.In this work,a sol–gel film transformation approach was developed to fabricate high-strength PNF paper.Iron ions formed coordination bonds between PNFs to obtain a preforming three-dimensional,interconnective nanofiber network.Subsequently,polytetrafluoroethylene(PTFE)particles were sprayed onto the surface of the paper,followed by thermal treatment to obtain double-layered PTFE-P/PNF nanocomposite paper.The nanocomposite paper presents incredible tensile strength(271.6 MPa,increased by 52.9%),folding endurance,super-hydrophobicity,and self-cleaning performances.Moreover,it exhibits low dielectric constant(2.06)and dielectric loss tangent(0.0133)values.According to the wave-transparent model for a doublelayered dielectric established by Maxwell’s equations,the wave-transparent coefficients of electromagnetic waves incident from both sides of the paper are 97.6%(PNF side)and 96.0%(PTFE/P(S-co-BCB-coMMA)side),respectively.The PTFE-P/PNF nanocomposite paper possesses great potential in the fields of wave-transparent applications.
基金Supported by the National Natural Science Foundation of China under Grant Nos.11274272,11304281,31201001by the Natural Science Foundation of Zhejiang Province under Grant Nos.Y6110250LY14A040001 and Zhejiang Ocean University(X12ZD10)
文摘We have investigated the dynamics of a protomer coupled to two different decoherent environments,each in a configuration called the spin star configuration.Using the quantum mechanics method,in different situations,we obtain the analytical expressions for the transition probability in the protomer system.In thermal equilibrium,there exist well-defined ranges of parameters for which decoherent interaction between the protomer and the environment assists energy transfer in the protomer system,while in pure quantum mechanics states,the decoherent interaction assists energy transfer for an eigenstate but against energy transfer for quantum mechanics averages.In particular,we also find that the dimerization of two bacteriochlorophylls in protomer can always assist energy transfer in certain parameter range,and in the appropriate spin bath energy,the efficiency of energy transport is sensitively depended on the temperature of environments.
