A series of hydrogels with lower critical solution temperature (LCST) were prepared and used for the immobilization of chymotrypsin. The activities of the immobilized enzyme decrease when the temperatures are raised a...A series of hydrogels with lower critical solution temperature (LCST) were prepared and used for the immobilization of chymotrypsin. The activities of the immobilized enzyme decrease when the temperatures are raised above their LCST and recover below their LCST. This property is reversible.展开更多
To solve the fundamental problem of insufficient heat available during defrosting while ensuring the efficient and safe system operation for air-source heat pumps (ASHPs). A novel reverse-cycle defrosting (NRCD) metho...To solve the fundamental problem of insufficient heat available during defrosting while ensuring the efficient and safe system operation for air-source heat pumps (ASHPs). A novel reverse-cycle defrosting (NRCD) method based on thermal energy storage to eliminate frost off the outdoor coil surface was developed. Comparative experiments using both the stand reverse cycle defrosting (SRCD) method and the NRCD method were carried out on an experimental ASHP unit with a nominal 2.5 kW heating capacity. The results indicate that during defrosting operation, using the NRCD method improves discharge and suction pressures by 0.24 MPa and 0.19 MPa, respectively, shortens defrosting duration by 60%, and reduces the defrosting energy consumption by 48.1% in the experimental environment, compared with those by the use of SRCD method. Therefore, using the NRCD method can shorten the defrosting duration, improve the indoor thermal comfort, and reduce the defrosting energy consumption in defrosting.展开更多
Using nonequilibrium molecular dynamics simulations, a comprehensive study of the asymmetric heat conduction in the composite system consisting of the Frenkel-Kontorova （FK） model and Fermi-Pasta-Ulam （FPU） model ...Using nonequilibrium molecular dynamics simulations, a comprehensive study of the asymmetric heat conduction in the composite system consisting of the Frenkel-Kontorova （FK） model and Fermi-Pasta-Ulam （FPU） model is conducted. The calculated results show that in a larger system, the rectifying direction can be reversed only by adjusting the thermal bias. Moreover, the rectification reversal depends critically on the system size and the properties of the interface. The mechanisms of the two types of asymmetric heat conduction induced by nonlinearity are discussed. Considering the novel asymmetric heat conduction in the system, it may possess possible applications to manage the thermal rectification in situ directionally without re-building the structure.展开更多
First-principles calculations are applied for investigating influence of electron donating ability of donor groups in eight thermally activated delayed fluorescence(TADF)molecules on their geometrical structures and t...First-principles calculations are applied for investigating influence of electron donating ability of donor groups in eight thermally activated delayed fluorescence(TADF)molecules on their geometrical structures and transition properties as well as reverse intersystem crossing(RISC)processes.Results show that the diphenylamine substitution in the donor part can slightly change the bond angle but decrease bond length between donor and acceptor unit except for the lowest triplet state(T1)of carbazole-xanthone molecule.As the electron donating ability of donor groups is increased,the overlap between the highest occupied molecular orbital(HOMO)and the lowest unoccupied molecular orbital(LUMO)is decreased.As the diphenylamine groups are added in donor part,the delocalization of HOMO is enlarged,which brings a decreased energy gap(ΔES1-T1)between the lowest singlet excited state(S1)and T1 state.Furthermore,with the calculated spin-orbit coupling coefficient(Hso),one finds that the larger value of<S1|Hso|T1>^2/ΔES1-T1^2 is,the faster the RISC is.The results show that all investigated molecules are promising candidates as TADF molecules.Overall,a wise molecular design strategy for TADF molecules,in which a smallΔES1-T1 can be achieved by enlarging the delocalization of frontier molecular orbitals with large separation between HOMO and LUMO,is proposed.展开更多
The double reversible transformations at low temperature in CuZnAlMnNi shape memory alloy were investigated by differential scanning calorimetry. It is found that the transformations occur not only in the as quenched ...The double reversible transformations at low temperature in CuZnAlMnNi shape memory alloy were investigated by differential scanning calorimetry. It is found that the transformations occur not only in the as quenched sample, but also in the as trained, as aged and as thermal cycled samples, and various treatments give rise to different influences on the transformation temperatures of the two transformations. Though the temperature interval between the two transformation peaks increases after training, aging and thermal cycling, the initial temperature of the M → A transformation is just the final temperature of the X → M transformation, namely, the X → M transformation is immediately followed by the M → A transformation upon heating.展开更多
In this paper, the magnetization reversal of the ferromagnetic layers in the IrMn/CoFe/AlOx/CoFe magnetic tunnel junction has been investigated using bulk magnetometry. The films exhibit very complex magnetization pro...In this paper, the magnetization reversal of the ferromagnetic layers in the IrMn/CoFe/AlOx/CoFe magnetic tunnel junction has been investigated using bulk magnetometry. The films exhibit very complex magnetization processes and reversal mechanism. Thermal activation phenomena such as the training effect, the asymmetry of reversal, the loop broadening and the decrease of exchange field while holding the film at negative saturation have been observed on the hysteresis loops of the pinned ferromagnetic layer while not on those of the free ferromagnetic layer. The thermal activation phenomena observed can be explained by the model of two energy barrier distributions with different time constants.展开更多
Bimetallic lined steel pipe （LSP） is a new anti-corrosion technology. It is widely used to transport oil, gas, water and corrosive liquid chemicals. At present, the hydroforming pressure for LSP has been investigate...Bimetallic lined steel pipe （LSP） is a new anti-corrosion technology. It is widely used to transport oil, gas, water and corrosive liquid chemicals. At present, the hydroforming pressure for LSP has been investigated theoretically and experimentally by most researchers. However, there are a few reports on the thermal strength of bimetallic LSP. Actually, the bimetallic LSP will be subjected to remarkable thermal load in the process of three layer polyethylene （3PE） external coating. Reverse yielding failure may occur on the inner pipe of the bimetallic LSP when it suffers from remarkable thermal load and residual contact pressure simultaneously. The aim of this paper is to study the thermal load and strength of the bimetallic LSP. A mechanical model, which can estimate the thermal strength of the bimetallic LSP, was established based on the elastic theory and the manufacture of the bimetallic LSP. Based on the model, the correlation between the thermal strength of the bimetallic LSP and residual contact pressure and wall thickness of the inner pipe was obtained. Reverse yielding experiments were performed on the LSP （NT80SS-316L） under different thermal loads. Experiment results are consistent with calculated results from the theoretical model. The experimental and simulation results may provide powerful guidance for the bimetallic LSP production and use.展开更多
The nonlinear J-E characteristics under self-heating equilibrium for conductive composites based on high density polyethylene were studied. The results show that there are identical conduction mechanisms under self-he...The nonlinear J-E characteristics under self-heating equilibrium for conductive composites based on high density polyethylene were studied. The results show that there are identical conduction mechanisms under self-heating equilibrium for the composites with various initial resistivities determined by filler content or ambient temperature. The nonlinear conduction behavior was involved in the limited microstructure transformations of the conducting network induced by electrical field applied and the corresponding self-heating effect. A reversible thermal fuse (RTF) model was suggested to interpret the physical origin of the nonlinear J-E characteristics.展开更多
The aftereffect field of thermal activation, which corresponds to the fluctuation field of a domain wall, is investigated via specific measurements of the magnetization behavior in PraFel4B nanocrystalline magnets. Th...The aftereffect field of thermal activation, which corresponds to the fluctuation field of a domain wall, is investigated via specific measurements of the magnetization behavior in PraFel4B nanocrystalline magnets. The thermal activation is a magnetization reversal arising from thermal fluctuation over an energy barrier to an equilibrate state. According to the magnetic viscosity and the field sweep rate dependence of the coercivity, the calculated values of the fluctuation field are lower than the aftereffect field and in a range between those of domain walls and individual grains. Based on these results, we propose that the magnetization reversal occurs in multiple ways involving grain activation and domain wall activation in thermal activation, and the thermal activation decreases the coercivity by-0.2 kOe in the PrzFe14B ribbons.展开更多
文摘A series of hydrogels with lower critical solution temperature (LCST) were prepared and used for the immobilization of chymotrypsin. The activities of the immobilized enzyme decrease when the temperatures are raised above their LCST and recover below their LCST. This property is reversible.
基金Project(50606007) supported by the National Natural Science Foundation of China
文摘To solve the fundamental problem of insufficient heat available during defrosting while ensuring the efficient and safe system operation for air-source heat pumps (ASHPs). A novel reverse-cycle defrosting (NRCD) method based on thermal energy storage to eliminate frost off the outdoor coil surface was developed. Comparative experiments using both the stand reverse cycle defrosting (SRCD) method and the NRCD method were carried out on an experimental ASHP unit with a nominal 2.5 kW heating capacity. The results indicate that during defrosting operation, using the NRCD method improves discharge and suction pressures by 0.24 MPa and 0.19 MPa, respectively, shortens defrosting duration by 60%, and reduces the defrosting energy consumption by 48.1% in the experimental environment, compared with those by the use of SRCD method. Therefore, using the NRCD method can shorten the defrosting duration, improve the indoor thermal comfort, and reduce the defrosting energy consumption in defrosting.
基金supported by the Natural Science Foundation of Hunan Province,China(Grant No.12JJ3009)the Changsha Science and Technology Plan Projects,Chinathe Science and Technology Plan Projects of Hunan Province,China(Grant No.2013SK3148)
文摘Using nonequilibrium molecular dynamics simulations, a comprehensive study of the asymmetric heat conduction in the composite system consisting of the Frenkel-Kontorova （FK） model and Fermi-Pasta-Ulam （FPU） model is conducted. The calculated results show that in a larger system, the rectifying direction can be reversed only by adjusting the thermal bias. Moreover, the rectification reversal depends critically on the system size and the properties of the interface. The mechanisms of the two types of asymmetric heat conduction induced by nonlinearity are discussed. Considering the novel asymmetric heat conduction in the system, it may possess possible applications to manage the thermal rectification in situ directionally without re-building the structure.
基金This work was supported by the National Natural Science Foundation of China(No.11374195 and No.21403133),the Taishan Scholar Project of Shandong Province,the Promotive Research Fund for Excellent Young and Middle-aged Scientists of Shandong Province(No.BS2014CL001),and the General Financial Grant from the China Postdoctoral Science Foundation(No.2014M560571).
文摘First-principles calculations are applied for investigating influence of electron donating ability of donor groups in eight thermally activated delayed fluorescence(TADF)molecules on their geometrical structures and transition properties as well as reverse intersystem crossing(RISC)processes.Results show that the diphenylamine substitution in the donor part can slightly change the bond angle but decrease bond length between donor and acceptor unit except for the lowest triplet state(T1)of carbazole-xanthone molecule.As the electron donating ability of donor groups is increased,the overlap between the highest occupied molecular orbital(HOMO)and the lowest unoccupied molecular orbital(LUMO)is decreased.As the diphenylamine groups are added in donor part,the delocalization of HOMO is enlarged,which brings a decreased energy gap(ΔES1-T1)between the lowest singlet excited state(S1)and T1 state.Furthermore,with the calculated spin-orbit coupling coefficient(Hso),one finds that the larger value of<S1|Hso|T1>^2/ΔES1-T1^2 is,the faster the RISC is.The results show that all investigated molecules are promising candidates as TADF molecules.Overall,a wise molecular design strategy for TADF molecules,in which a smallΔES1-T1 can be achieved by enlarging the delocalization of frontier molecular orbitals with large separation between HOMO and LUMO,is proposed.
文摘The double reversible transformations at low temperature in CuZnAlMnNi shape memory alloy were investigated by differential scanning calorimetry. It is found that the transformations occur not only in the as quenched sample, but also in the as trained, as aged and as thermal cycled samples, and various treatments give rise to different influences on the transformation temperatures of the two transformations. Though the temperature interval between the two transformation peaks increases after training, aging and thermal cycling, the initial temperature of the M → A transformation is just the final temperature of the X → M transformation, namely, the X → M transformation is immediately followed by the M → A transformation upon heating.
基金supported by the National Natural Science Foundation of China (Grant No 50671048)
文摘In this paper, the magnetization reversal of the ferromagnetic layers in the IrMn/CoFe/AlOx/CoFe magnetic tunnel junction has been investigated using bulk magnetometry. The films exhibit very complex magnetization processes and reversal mechanism. Thermal activation phenomena such as the training effect, the asymmetry of reversal, the loop broadening and the decrease of exchange field while holding the film at negative saturation have been observed on the hysteresis loops of the pinned ferromagnetic layer while not on those of the free ferromagnetic layer. The thermal activation phenomena observed can be explained by the model of two energy barrier distributions with different time constants.
基金supported by National Natural Science Foundation of China(U2003123,22172184)Weiqiao-UCAS Special Projects on Low-Carbon Technology Development(GYY-DTFZ-2022-015)+1 种基金Fundamental Research Project of ICC-CAS(SCJC-DT-2022-04)Open Fund of State Key Laboratory of Coal and CBM Co-mining(2022KF23)。
基金financial support from the National Natural Science Foundation of China (Nos. 51004084, 51274170)the Doctoral Fund of Ministry of Education of China (No. 20105121120002)
文摘Bimetallic lined steel pipe （LSP） is a new anti-corrosion technology. It is widely used to transport oil, gas, water and corrosive liquid chemicals. At present, the hydroforming pressure for LSP has been investigated theoretically and experimentally by most researchers. However, there are a few reports on the thermal strength of bimetallic LSP. Actually, the bimetallic LSP will be subjected to remarkable thermal load in the process of three layer polyethylene （3PE） external coating. Reverse yielding failure may occur on the inner pipe of the bimetallic LSP when it suffers from remarkable thermal load and residual contact pressure simultaneously. The aim of this paper is to study the thermal load and strength of the bimetallic LSP. A mechanical model, which can estimate the thermal strength of the bimetallic LSP, was established based on the elastic theory and the manufacture of the bimetallic LSP. Based on the model, the correlation between the thermal strength of the bimetallic LSP and residual contact pressure and wall thickness of the inner pipe was obtained. Reverse yielding experiments were performed on the LSP （NT80SS-316L） under different thermal loads. Experiment results are consistent with calculated results from the theoretical model. The experimental and simulation results may provide powerful guidance for the bimetallic LSP production and use.
基金the National Advanced Material Committee of China (NAMCC)，国家自然科学基金
文摘The nonlinear J-E characteristics under self-heating equilibrium for conductive composites based on high density polyethylene were studied. The results show that there are identical conduction mechanisms under self-heating equilibrium for the composites with various initial resistivities determined by filler content or ambient temperature. The nonlinear conduction behavior was involved in the limited microstructure transformations of the conducting network induced by electrical field applied and the corresponding self-heating effect. A reversible thermal fuse (RTF) model was suggested to interpret the physical origin of the nonlinear J-E characteristics.
基金Project supported by the Knowledge Innovation Project of the Chinese Academy of Sciences and the National Basic Research Program of China
文摘The aftereffect field of thermal activation, which corresponds to the fluctuation field of a domain wall, is investigated via specific measurements of the magnetization behavior in PraFel4B nanocrystalline magnets. The thermal activation is a magnetization reversal arising from thermal fluctuation over an energy barrier to an equilibrate state. According to the magnetic viscosity and the field sweep rate dependence of the coercivity, the calculated values of the fluctuation field are lower than the aftereffect field and in a range between those of domain walls and individual grains. Based on these results, we propose that the magnetization reversal occurs in multiple ways involving grain activation and domain wall activation in thermal activation, and the thermal activation decreases the coercivity by-0.2 kOe in the PrzFe14B ribbons.
