Abstract: In a laboratory study, indica and japonica rice (Oryza sativa L.) seeds were exposed to thermal hardening (heating followed by chilling followed by heating; chilling followed by heating followed by chilling;...Abstract: In a laboratory study, indica and japonica rice (Oryza sativa L.) seeds were exposed to thermal hardening (heating followed by chilling followed by heating; chilling followed by heating followed by chilling; heating followed by chilling or chilling followed by heating). In indica rice, heating followed by chilling followed by heating resulted in decreased mean germination time, time to start germination, electrical conductivity of seed leachates, and time to 50% germination, as well as increased germination index, energy of germination, radicle and plumule length, root length, root/shoot ratio, root fresh and dry weight, radicle and plumule growth rate, and shoot fresh weight. In japonica rice, chilling followed by heating followed by chilling performed better than all other treatments, including control.展开更多
A multifunctional amine, 1,4-bis（2,4-diaminophenoxy）benzene（14 BDAPOB）, was prepared and used as a novel hardener for novolac epoxy resin（ER）. The structure of 14 BDAPOB was characterized with Fourier transform ...A multifunctional amine, 1,4-bis（2,4-diaminophenoxy）benzene（14 BDAPOB）, was prepared and used as a novel hardener for novolac epoxy resin（ER）. The structure of 14 BDAPOB was characterized with Fourier transform infrared（FT-IR） spectroscopy and differential scanning calorimetry（DSC）. The curing kinetics of the novolac epoxy resin/1,4-bis（2,4-diaminophenoxy）benzene（ER/14 BDAPOB） system was studied by means of non-isothermal DSC experiments at five heating rates and determined by the Kissinger, Ozawa and Crane methods. The results showed that the activation energy Ea of the ER/14 BDAPOB（74.56 kJ/mol） system was higher than that of the epoxy resin/LCA-30（ER/LCA-30, 68.85 kJ/mol）, where LCA-30 is a commercial modified diamine. The reaction order, frequency factor and the reaction rate constant at peak temperature of the two systems were calculated. The initial decomposition temperatures（Tonset） were 398.8 ℃（ER/14 BDAPOB）and 334.3 ℃（ER/LCA-30）. The tensile shear strengths were 21.63 MPa（ER/14 BDAPOB） and 21.28 MPa（ER/LCA-30）. The results showed that the two cured systems exhibited good thermal and mechanical properties.展开更多
The eutectic CoFeNi2V0.5Nb0.75 high entropy alloys （HEAs） were heated at 500, 600, 700, 800 and 1000 ℃, respectively for 6 h and subsequently quenched in the water to investigate their thermal stability and phase t...The eutectic CoFeNi2V0.5Nb0.75 high entropy alloys （HEAs） were heated at 500, 600, 700, 800 and 1000 ℃, respectively for 6 h and subsequently quenched in the water to investigate their thermal stability and phase transformation at high temperature. The microstructure and mechanical properties of the samples were investigated by scanning electron microscopy, X-ray diffraction, compressive and hardness tests. It was found that the as-cast CoFeNi2V0.5Nb0.75 HEAs showed a eutectic microstructure with alternating fcc solid solution phase and Fe2Nb-type Laves phase. The NbNi4-type intermetallic phase appeared when the heat-treated temperature was higher than 600 ℃. With increasing quenching temperature, the volume fraction of the NbNi4-type intermetallic phase increased while that of the eutectic regions decreased. The sample quenched at 800 ℃ showed the most excellent comprehensive mechanical properties; its fracture strength, yield strength and plastic strain were as high as 2586.76 MPa, 2075.18 MPa and 16.73%, respectively. Moreover, the eutectic CoFeNi2V0.5Nb0.75 HEAs exhibited apparent age hardening, especially quenched at 700 ℃, the hardness reached up to the maximum value of HV 727.52.展开更多
文摘Abstract: In a laboratory study, indica and japonica rice (Oryza sativa L.) seeds were exposed to thermal hardening (heating followed by chilling followed by heating; chilling followed by heating followed by chilling; heating followed by chilling or chilling followed by heating). In indica rice, heating followed by chilling followed by heating resulted in decreased mean germination time, time to start germination, electrical conductivity of seed leachates, and time to 50% germination, as well as increased germination index, energy of germination, radicle and plumule length, root length, root/shoot ratio, root fresh and dry weight, radicle and plumule growth rate, and shoot fresh weight. In japonica rice, chilling followed by heating followed by chilling performed better than all other treatments, including control.
文摘A multifunctional amine, 1,4-bis（2,4-diaminophenoxy）benzene（14 BDAPOB）, was prepared and used as a novel hardener for novolac epoxy resin（ER）. The structure of 14 BDAPOB was characterized with Fourier transform infrared（FT-IR） spectroscopy and differential scanning calorimetry（DSC）. The curing kinetics of the novolac epoxy resin/1,4-bis（2,4-diaminophenoxy）benzene（ER/14 BDAPOB） system was studied by means of non-isothermal DSC experiments at five heating rates and determined by the Kissinger, Ozawa and Crane methods. The results showed that the activation energy Ea of the ER/14 BDAPOB（74.56 kJ/mol） system was higher than that of the epoxy resin/LCA-30（ER/LCA-30, 68.85 kJ/mol）, where LCA-30 is a commercial modified diamine. The reaction order, frequency factor and the reaction rate constant at peak temperature of the two systems were calculated. The initial decomposition temperatures（Tonset） were 398.8 ℃（ER/14 BDAPOB）and 334.3 ℃（ER/LCA-30）. The tensile shear strengths were 21.63 MPa（ER/14 BDAPOB） and 21.28 MPa（ER/LCA-30）. The results showed that the two cured systems exhibited good thermal and mechanical properties.
基金supported by the National Natural Science Foundation of China (Nos. 51104029, 51134013, 51471044, 51104029 and 51375070)the Fundamental Research Funds for the Central Universitiesthe Natural Science Foundation of Liaoning Province (No. 2014028013)
文摘The eutectic CoFeNi2V0.5Nb0.75 high entropy alloys （HEAs） were heated at 500, 600, 700, 800 and 1000 ℃, respectively for 6 h and subsequently quenched in the water to investigate their thermal stability and phase transformation at high temperature. The microstructure and mechanical properties of the samples were investigated by scanning electron microscopy, X-ray diffraction, compressive and hardness tests. It was found that the as-cast CoFeNi2V0.5Nb0.75 HEAs showed a eutectic microstructure with alternating fcc solid solution phase and Fe2Nb-type Laves phase. The NbNi4-type intermetallic phase appeared when the heat-treated temperature was higher than 600 ℃. With increasing quenching temperature, the volume fraction of the NbNi4-type intermetallic phase increased while that of the eutectic regions decreased. The sample quenched at 800 ℃ showed the most excellent comprehensive mechanical properties; its fracture strength, yield strength and plastic strain were as high as 2586.76 MPa, 2075.18 MPa and 16.73%, respectively. Moreover, the eutectic CoFeNi2V0.5Nb0.75 HEAs exhibited apparent age hardening, especially quenched at 700 ℃, the hardness reached up to the maximum value of HV 727.52.
