The high pressure pneumatic system has been applied to special industries. It may cause errors when we analyze high pressure pneumatics under ideal gas assumption. However, the real gas effect on the performances of h...The high pressure pneumatic system has been applied to special industries. It may cause errors when we analyze high pressure pneumatics under ideal gas assumption. However, the real gas effect on the performances of high pressure pneumatics is seldom investigated. In this paper, the real gas effects on air enthalpy and internal energy are estimated firstly to study the real gas effect on the energy conversion. Under ideal gas assumption, enthalpy and internal energy are solely related to air temperature. The estimation result indicates that the pressure enthalpy and pressure internal energy of real pneumatic air obviously decrease the values of enthalpy and internal energy for high pressure pneumatics, and the values of pressure enthalpy and pressure internal energy are close. Based on the relationship among pressure, enthalpy and internal energy, the real gas effects on charging and discharging processes of high pressure pneumatics are estimated, which indicates that the real gas effect accelerates the temperature and pressure decreasing rates during discharging process, and decelerates their increasing rates during charging process. According to the above analysis, and for the inconvenience in building the simulation model for real gas and the difficulty of measuring the detail thermal capacities of pneumatics, a method to compensate the real gas effect under ideal gas assumption is proposed by modulating the thermal capacity of the pneumatic container in simulation. The experiments of switching expansion reduction （SER） for high pressure pneumatics are used to verify this compensating method. SER includes the discharging process of supply tanks and the charging process of expansion tank. The simulated and experimental results of SER are highly consistent. The proposed compensation method provides a convenient way to obtain more realistic simulation results for high pressure pneumatics.展开更多
SEISMIC wave inversion is one of the most important means for us to recognize the compositionand structure of the Earth’s interior.Although the experimental techniques of elastic wave ve-locity measurement at in situ...SEISMIC wave inversion is one of the most important means for us to recognize the compositionand structure of the Earth’s interior.Although the experimental techniques of elastic wave ve-locity measurement at in situ high pressure and temperature develop very fast in recent展开更多
Interface and scale effects are the two most important factors which strongly affect the structure and the properties of nano-/micro-crystals under pressure.We conduct an experiment under high pressure in situ alterna...Interface and scale effects are the two most important factors which strongly affect the structure and the properties of nano-/micro-crystals under pressure.We conduct an experiment under high pressure in situ alternating current impedance to elucidate the effects of interface on the structure and electrical transport behavior of two Zn Se samples with different sizes obtained by physical grinding.The results show that（i） two different-sized Zn Se samples undergo the same phase transitions from zinc blend to cinnabar-type phase and then to rock salt phase;（ii） the structural transition pressure of the859-nm Zn Se sample is higher than that of the sample of 478 nm,which indicates the strong scale effect.The pressure induced boundary resistance change is obtained by fitting the impedance spectrum,which shows that the boundary conduction dominates the electrical transport behavior of Zn Se in the whole experimental pressure range.By comparing the impedance spectra of two different-sized Zn Se samples at high pressure,we find that the resistance of the 478-nm Zn Se sample is lower than that of the 859-nm sample,which illustrates that the sample with smaller particle size has more defects which are due to physical grinding.展开更多
A high-quality SrFe0.8Co0.2O3 single crystal is prepared by combining floating-zone and high-pressure treatment methods. Its Magnetocaloric effect is investigated by magnetic measurements. A paramagnetism-to-ferromagn...A high-quality SrFe0.8Co0.2O3 single crystal is prepared by combining floating-zone and high-pressure treatment methods. Its Magnetocaloric effect is investigated by magnetic measurements. A paramagnetism-to-ferromagnetism tran- sition is found at about 270 K and this transition is a second-order one in nature as confirmed by Arrott plots. The saturated moment obtained at 2 K and 7 T is 3.63 μB/f.u. The maximal value of magnetic entropy change measured at 5 T is about 4.0 J·kg-1 ·K-1. The full wide at half maximum for a magnetic entropy change peak observed in SrFe0.8Co0.2O3 is considerably large. As a consequence, the relative cooling power value of SrFe0.8Co0.2O3 obtained at 5 T is 331 J/kg, which is greatly higher than those observed in other perovskite oxides. The present work therefore provides a promising candidate for magnetic refrigeration near room temperature.展开更多
Studies so far indicate that many processes in the interactions between biomacromole-cules are accompanied by a change in occupied volume. For instance, the association ofprotein subunits into oligomer and the formati...Studies so far indicate that many processes in the interactions between biomacromole-cules are accompanied by a change in occupied volume. For instance, the association ofprotein subunits into oligomer and the formation of protein-nucleic acid complex give anincrease in volume. The increase in volume in these processes mainly results from: (i) theformation of the dead space between the subunits of the oligomeric protein or the com-plexes in the processes mentioned above; (ii) the formation of salt bonds and (iii) theinteractions between hydrophobic groups. It is known from the Lechatelier principle that ifhigh pressure is applied to an equilibrium system mentioned above, the original展开更多
In situ high pressure XRD diffraction and Raman spectroscopy have been performed on 12 nm CeO2 nanoparticles. Surprisingly, under quasihydrostatic conditions, 12 nm CeO2 nanoparticles maintain the fluorite- type struc...In situ high pressure XRD diffraction and Raman spectroscopy have been performed on 12 nm CeO2 nanoparticles. Surprisingly, under quasihydrostatic conditions, 12 nm CeO2 nanoparticles maintain the fluorite- type structure in the whole pressure range （0-51 GPa） during the experiments, much more stable than the bulk counterpart （PT-31 GPa）. In contrast, they experienced phase transition at pressure as low as 26 GPa under non- hydrostatic conditions （adopting CsC1 as pressure medium）. Additionally, 32-36 nm CeO2 nanoparticles exhibit an onset pressure of phase transition at 35 GPa under quasihydrostatic conditions, and this onset pressure is much lower than our result. Further analysis shows both the experimental condition （i.e., quasihydrostatic or non-hydrostatic） and grain size effect have a significant impact on the high pressure behaviors of CeO2 nanomaterials.展开更多
We systematically investigate the effect of pressure on the magnetic properties of GdCo2B2 on the basis of alternating current（AC） susceptibility,AC heat capacity and electrical resistivity measurements under pressu...We systematically investigate the effect of pressure on the magnetic properties of GdCo2B2 on the basis of alternating current（AC） susceptibility,AC heat capacity and electrical resistivity measurements under pressures up to 2.2 GPa.A detailed magnetic phase diagram under pressure is determined.GdCo2B2 exhibits three anomalies that apparently reflect magnetic phase transitions,respectively,at temperatures TC= 20.5 K,T1= 18.0 K and TN= 11.5 K under ambient pressure.Under pressures up to 2.2 GPa,these anomalies are observed to slightly increase at TCand T1,and they coincide with each other above 1.6 GPa.Conversely,they decrease at TN and disappear under pressures higher than 1.4 GPa.The results indicate that the low-temperature magnetic phases can be easily suppressed by pressure.Moreover,the spin-glass-like behavior of GdCo2B2 is examined in terms of magnetization,aging effect and frequency dependence of AC susceptibility.A separation between the zero-field-cooled（ZFC） and field-cooled（FC） magnetization curves becomes evident at a low magnetic field of 0.001 T.A long-time relaxation behavior is observed at 4 K.The freezing temperature Tfincreases with frequency increasing.展开更多
基金supported by National Natural Science Foundation of China (Grant No. 50575202)
文摘The high pressure pneumatic system has been applied to special industries. It may cause errors when we analyze high pressure pneumatics under ideal gas assumption. However, the real gas effect on the performances of high pressure pneumatics is seldom investigated. In this paper, the real gas effects on air enthalpy and internal energy are estimated firstly to study the real gas effect on the energy conversion. Under ideal gas assumption, enthalpy and internal energy are solely related to air temperature. The estimation result indicates that the pressure enthalpy and pressure internal energy of real pneumatic air obviously decrease the values of enthalpy and internal energy for high pressure pneumatics, and the values of pressure enthalpy and pressure internal energy are close. Based on the relationship among pressure, enthalpy and internal energy, the real gas effects on charging and discharging processes of high pressure pneumatics are estimated, which indicates that the real gas effect accelerates the temperature and pressure decreasing rates during discharging process, and decelerates their increasing rates during charging process. According to the above analysis, and for the inconvenience in building the simulation model for real gas and the difficulty of measuring the detail thermal capacities of pneumatics, a method to compensate the real gas effect under ideal gas assumption is proposed by modulating the thermal capacity of the pneumatic container in simulation. The experiments of switching expansion reduction （SER） for high pressure pneumatics are used to verify this compensating method. SER includes the discharging process of supply tanks and the charging process of expansion tank. The simulated and experimental results of SER are highly consistent. The proposed compensation method provides a convenient way to obtain more realistic simulation results for high pressure pneumatics.
文摘SEISMIC wave inversion is one of the most important means for us to recognize the compositionand structure of the Earth’s interior.Although the experimental techniques of elastic wave ve-locity measurement at in situ high pressure and temperature develop very fast in recent
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11404133 and 11374121)the Program of Science and Technology Development Plan of Jilin Province,China(Grant No.20140520105JH)
文摘Interface and scale effects are the two most important factors which strongly affect the structure and the properties of nano-/micro-crystals under pressure.We conduct an experiment under high pressure in situ alternating current impedance to elucidate the effects of interface on the structure and electrical transport behavior of two Zn Se samples with different sizes obtained by physical grinding.The results show that（i） two different-sized Zn Se samples undergo the same phase transitions from zinc blend to cinnabar-type phase and then to rock salt phase;（ii） the structural transition pressure of the859-nm Zn Se sample is higher than that of the sample of 478 nm,which indicates the strong scale effect.The pressure induced boundary resistance change is obtained by fitting the impedance spectrum,which shows that the boundary conduction dominates the electrical transport behavior of Zn Se in the whole experimental pressure range.By comparing the impedance spectra of two different-sized Zn Se samples at high pressure,we find that the resistance of the 478-nm Zn Se sample is lower than that of the 859-nm sample,which illustrates that the sample with smaller particle size has more defects which are due to physical grinding.
基金supported by the National Basic Research Program of China(Grant No.2014CB921500)the Strategic Priority Research Program of the Chinese Academy of Sciences(Grant No.XDB07030300)
文摘A high-quality SrFe0.8Co0.2O3 single crystal is prepared by combining floating-zone and high-pressure treatment methods. Its Magnetocaloric effect is investigated by magnetic measurements. A paramagnetism-to-ferromagnetism tran- sition is found at about 270 K and this transition is a second-order one in nature as confirmed by Arrott plots. The saturated moment obtained at 2 K and 7 T is 3.63 μB/f.u. The maximal value of magnetic entropy change measured at 5 T is about 4.0 J·kg-1 ·K-1. The full wide at half maximum for a magnetic entropy change peak observed in SrFe0.8Co0.2O3 is considerably large. As a consequence, the relative cooling power value of SrFe0.8Co0.2O3 obtained at 5 T is 331 J/kg, which is greatly higher than those observed in other perovskite oxides. The present work therefore provides a promising candidate for magnetic refrigeration near room temperature.
文摘Studies so far indicate that many processes in the interactions between biomacromole-cules are accompanied by a change in occupied volume. For instance, the association ofprotein subunits into oligomer and the formation of protein-nucleic acid complex give anincrease in volume. The increase in volume in these processes mainly results from: (i) theformation of the dead space between the subunits of the oligomeric protein or the com-plexes in the processes mentioned above; (ii) the formation of salt bonds and (iii) theinteractions between hydrophobic groups. It is known from the Lechatelier principle that ifhigh pressure is applied to an equilibrium system mentioned above, the original
基金Supported by National Basic Research Program of China(2011CB808200)NSFC(10979001,51025206,51032001,21073071,11004075,11004072,11104105,11079040)Cheung Kong Scholars Programme of China
文摘In situ high pressure XRD diffraction and Raman spectroscopy have been performed on 12 nm CeO2 nanoparticles. Surprisingly, under quasihydrostatic conditions, 12 nm CeO2 nanoparticles maintain the fluorite- type structure in the whole pressure range （0-51 GPa） during the experiments, much more stable than the bulk counterpart （PT-31 GPa）. In contrast, they experienced phase transition at pressure as low as 26 GPa under non- hydrostatic conditions （adopting CsC1 as pressure medium）. Additionally, 32-36 nm CeO2 nanoparticles exhibit an onset pressure of phase transition at 35 GPa under quasihydrostatic conditions, and this onset pressure is much lower than our result. Further analysis shows both the experimental condition （i.e., quasihydrostatic or non-hydrostatic） and grain size effect have a significant impact on the high pressure behaviors of CeO2 nanomaterials.
基金Project supported by JSPS KAKENHI(Grant No.24540366,Grant-in-Aid for Scientific Research(C))
文摘We systematically investigate the effect of pressure on the magnetic properties of GdCo2B2 on the basis of alternating current（AC） susceptibility,AC heat capacity and electrical resistivity measurements under pressures up to 2.2 GPa.A detailed magnetic phase diagram under pressure is determined.GdCo2B2 exhibits three anomalies that apparently reflect magnetic phase transitions,respectively,at temperatures TC= 20.5 K,T1= 18.0 K and TN= 11.5 K under ambient pressure.Under pressures up to 2.2 GPa,these anomalies are observed to slightly increase at TCand T1,and they coincide with each other above 1.6 GPa.Conversely,they decrease at TN and disappear under pressures higher than 1.4 GPa.The results indicate that the low-temperature magnetic phases can be easily suppressed by pressure.Moreover,the spin-glass-like behavior of GdCo2B2 is examined in terms of magnetization,aging effect and frequency dependence of AC susceptibility.A separation between the zero-field-cooled（ZFC） and field-cooled（FC） magnetization curves becomes evident at a low magnetic field of 0.001 T.A long-time relaxation behavior is observed at 4 K.The freezing temperature Tfincreases with frequency increasing.
