The sea-level change is resulted from superposition of sun, moon and other planeries, and earth itself, biological process, atmosphere and oceanography, as well as artificial actions. As a result, the sea level change...The sea-level change is resulted from superposition of sun, moon and other planeries, and earth itself, biological process, atmosphere and oceanography, as well as artificial actions. As a result, the sea level change is really a sensitive integral variation value of many variations, or a combined function of coupling effects of various big systems. Therefore the above mentioned superposed action of different systems and the coupling effect of sun earth and biological aspects may be called as sun earth biological coupling effect system. Based on this hypothesis, the corresponding sun dynamic, air dynamic, water dynamic and earth dynamic conceptional models are established in order to research the multiple coupling effects and feedback machsnism between these big systems. In order to determine the relations, effectness and coherent relation of different variations, the quantity, analysis is conducted through collective variation and stage division. The quantity analysis indicates that the earths spindle rotation speed is the dynamic mechanism controlling the sea level change of fluctuation. The change rate of sea level in the world is +1.32 + 0.22 mm/a, while the sea level change rate in China is only+1.39 + 0.26 mm/a in average. If take the CO2 content as the climate marker, eight cold stages (periods) are grouped out since two hundreds years AC. The extreme cold of the eighth cold stage started approximately at 1850 years AC. and if the stage from the extreme cold to extreme warm is determined as long as 200 years, the present ongoing warm stage will end at about 2050 years, there after the temperature will begin to tower. If the stage between cold and warm extremes lasts for 250 years, then the temperature will become lower at about 2100 year. Until to that time, the sea-level is estimated to raise +7 - +11 + 3.5 cm again, and there after, the sea level will begin the new lowering trend. In the same time, the climate will enter into next new cold stage subsequently.展开更多
The effect of rare earth element on the solidification behavior of Al-Mg alloy was investigated in a directional solidification apparatus.It was found that during the solidification process.the rare earth element segr...The effect of rare earth element on the solidification behavior of Al-Mg alloy was investigated in a directional solidification apparatus.It was found that during the solidification process.the rare earth element segregated in the liquid at sold-liquid interface,changed the solidification morphology and reduced the secondary arm spacing markedly.展开更多
The amounts of rare earth in the solid solution in steel 16Mn were determined by means of inductive coupling plasma(ICP)spectroscopy.While the RE/S ratio was less than 1.9,the amounts of rare earth in solid solution w...The amounts of rare earth in the solid solution in steel 16Mn were determined by means of inductive coupling plasma(ICP)spectroscopy.While the RE/S ratio was less than 1.9,the amounts of rare earth in solid solution were not more than 8 ppm,which rised slightly with the increase of the rare earth content in the steel.While the RE/S was more than 1.9,MnS disappeared completely in the steel and the amounts of rare earth in solid solution increased rapidly with the increasing of the rare earth content.The solubility of cerium in steel 16 Mn(St 52)is less than 0.011 wt% at room temperature.The results also indicate that rare earth in solid solution can reduce the amount of pearlite and increase that of ferrite and its mierohardness.The rela- tionship between microhardness(Hv)and the amount of rare earth in solid solution can be expressed by the equation of Hv=117+7 RE(ppm).展开更多
The slow tensile tests,dynamic hydrogen charging tensile tests and hydrogen evolution tests after hydrogen charging were used to study the effects of rare earth metal(REM)on hydrogen behaviour in a steel 16Mn(St.52).T...The slow tensile tests,dynamic hydrogen charging tensile tests and hydrogen evolution tests after hydrogen charging were used to study the effects of rare earth metal(REM)on hydrogen behaviour in a steel 16Mn(St.52).The ratios of RE/S were chosen as 0,0.7,2.2 and 7.7,respectively.It was shown that the steel with RE/S = 2.2 give a lower hydrogen embrittlement susceptibility than others.The steels without REM can adsorb much more amount of hydrogen than that with REM under the same hydrogen charging conditions.And the amount of adsorbed hydrogen for the foriner can be evolved easier than that for the latter at room temperature,50℃ and 80℃,respectively.The experimental results were explained by the trap theory of hydrogen,the short-circuit diffusion paths in the interfaces between the elongated MnS inclusions and the matrix,and strong ability of REM to adsorb hydrogen.展开更多
Optical microscope(OM),scanning electron microscope(SEM),energy dispersive spectrometer (EDS) and X-ray Diffraction(XRD) were used to study the effects of rare earth on the microstructural characteristics of 55%Al-Zn-...Optical microscope(OM),scanning electron microscope(SEM),energy dispersive spectrometer (EDS) and X-ray Diffraction(XRD) were used to study the effects of rare earth on the microstructural characteristics of 55%Al-Zn-1.6%Si hot -dip coatings on steel.The results of OM,SEM and EDS showed that by adding RE into the 55%Al-Zn-1.6%Si bath,the saw-toothed shape of intermetallic reaction layer of coating became smooth,and the thickness of the overlay and intermetallic reaction layer decreased.The XRD results revealed that the intermetallic reaction layer was comprised of two different regions,a bright phase closest to the steel substrate with phases of Fe_2Al_3 and a dark phase closest to the metallic coating with phases of FeAl_3/α-Fe-Al-Si.展开更多
The total number of atmospheric particle (AP) is an important datum for planetary science and geoscience. Estimating entire AP number is also a familiar question in general physics. With standard atmosphere model, con...The total number of atmospheric particle (AP) is an important datum for planetary science and geoscience. Estimating entire AP number is also a familiar question in general physics. With standard atmosphere model, considering the number difference of AP caused by rough and uneven in the earth surface below, the sum of dry clean atmosphere particle is . So the whole number of AP including water vapor is . The rough estimation for the total number of AP on other planets (or satellites) in condensed state is also discussed on the base of it.展开更多
The effect of rare earth metals(REM)on the characteristics of auto-tempering and decomposition of martensite for low-carbon and low-alloy steels(20SiMn2V and 20SiMn2VRE)was investigated using TEM,dilatometer and micro...The effect of rare earth metals(REM)on the characteristics of auto-tempering and decomposition of martensite for low-carbon and low-alloy steels(20SiMn2V and 20SiMn2VRE)was investigated using TEM,dilatometer and microhardness test.Results show that both ε.and θ carbides,during auto-tempering, may precipitate from the low-carbon martensite matrix at the same time in the 20SiMn2V steel,however,the precipitation of the ε-carbides can be inhibited by the REM contained in the 20SiMn2 VRE steel,resulting in change of the type of precipitated carbides and decrease of the extent of auto-tempering.The“in-situ”ob- servations show that the decomposition of martensite is also inhibited by the REM contained in the 20SiMn2 VRE steel during low temperature tempering.展开更多
The surface functions produced by adding 14 rare earth oxides in Ni/γ Al 2O 3 system were determined by BET, gas chromatography, infrared spectroscopy, XRD, SEM, X ray electronic energy spectrum etc, and research...The surface functions produced by adding 14 rare earth oxides in Ni/γ Al 2O 3 system were determined by BET, gas chromatography, infrared spectroscopy, XRD, SEM, X ray electronic energy spectrum etc, and researched contrastively. The results show that the addition of rare earth oxides changes the property of catalyst surface. It is of benefit to increasing the number of active center of the catalyst and the surface acidity of the catalyst, decreasing the surface carbon deposit during the reaction. Moreover, the addition of rare earth oxides influences the electronic state of nickel atoms on the surface directly and produces electronic effect. The effect is different for each rare earth element.展开更多
The effective earth radius factor(k-factor)has a refractive propagation effect on transmitted radio signals thus making its study necessary for the proper planning of terrestrial radio links and power budget.This stud...The effective earth radius factor(k-factor)has a refractive propagation effect on transmitted radio signals thus making its study necessary for the proper planning of terrestrial radio links and power budget.This study was carried out over the city of Lokoja,Nigeria,using ten years(2011 to 2020)atmospheric data of temperature,pressure and humidity both at the surface(12 m)and at 100 m AGL.The data were retrieved from European Centre for Medium-Range Weather Forecasts(ECMWF)ERA5.The k-factor yearly variation follows the same trend with minimum and maximum values obtained during dry and wet season months respectively.In addition,the highest mean value of 1.00042 was recorded in the month of August while the lowest value of 1.00040 was recorded in the month of January with an overall mean value of 1.0003.This value is less than the recommended standard of 1.33 by ITU-R.The propagation effect corresponding to k<1.33 is sub-refractive.The implication of this on radio wave propagation,especially terrestrial communications is that transmitted wireless signal is prone to losses.This can be mitigated through an effective power budget:Choice of transmitting antenna’s height and gain,so as to improve the Quality of Service over the study area.展开更多
The self-healing effect of electrochemically deposited CeO2-Ce2O3 films on stainless steel OC404(SS) in 0.5 mol/L NaCl solution was studied. It was established that the corrosion potential of the steel, after coveri...The self-healing effect of electrochemically deposited CeO2-Ce2O3 films on stainless steel OC404(SS) in 0.5 mol/L NaCl solution was studied. It was established that the corrosion potential of the steel, after covering it with CeO2-Ce2O3 layer and thermal treatment(i.e. potential of the system CeO2-Ce2O3/SSt.t.), was shifted sharply to a considerably more positive value, while the corrosion current was reduced noticeably. The X-ray photoelectron spectroscopy(XPS), energy dispersive spectroscopy(EDS) and scanning electron microscopy(SEM) analyses on the observed scratched surface area of the system CeO2-Ce2O3/SSt.t., after exposure of investigated specimens to 0.5 mol/L NaCl corrosion media, showed partial accumulation of ceria, as well as remarkable increase in the concentrations of oxides of Al, Cr and Fe, on the mechanically revealed steel surface. On the basis of the obtained results one could conclude that the secondary passive oxide/hydroxide films, formed after a definite time interval of exposure to corrosion media, acted as barriers, hindering the corrosion processes in active zones. A hypothesis was put forward about the mechanism of self-repairing oxide layers on the steel surface and their corrosion protection effect respectively.展开更多
The structure, magnetic and magnetocaloric properties of the Ge-rich Gd5Ge2.05-xSi1.95-xMn2x (x=0.01 and 0.03) alloys were investigated by scanning electron microscopy, X-ray powder diffraction, differential scannin...The structure, magnetic and magnetocaloric properties of the Ge-rich Gd5Ge2.05-xSi1.95-xMn2x (x=0.01 and 0.03) alloys were investigated by scanning electron microscopy, X-ray powder diffraction, differential scanning calorimeter (DSC) and magnetization measurements. The results of energy dispersive X-ray analysis (EDX) and X-ray diffraction analyses showed that the composition and crystal structure of the alloys were desired. DSC measurements were performed to determine the transformation temperatures for each alloy. Both alloys exhibited the first order phase transition around room temperature. The alloys showed an anti-ferromagnetic transition around 60 K. The isothermal magnetic entropy changes of the alloys were determined from the isothermal magnetization measurements by using the Maxwell relation. The maximum values of isothermal magnetic entropy change of the Gd5Ge2.05-xSi1.95-xMn2x alloy with x=0.01 was found to be -12.1 and -19.8 J/(kg·K) using Maxwell equation around 268 K in applied fields of 2 and 5 T, respectively.展开更多
The microstructure, magnetic entropy changes, hysteresis and magnetic properties of La_(0.8)Ce_(0.2)Fe_(11.5)Al_(1.5–x)Si_x(x=0.4, 0.5, 0.6, 0.7) compounds were studied by X-ray diffraction(XRD) and a sup...The microstructure, magnetic entropy changes, hysteresis and magnetic properties of La_(0.8)Ce_(0.2)Fe_(11.5)Al_(1.5–x)Si_x(x=0.4, 0.5, 0.6, 0.7) compounds were studied by X-ray diffraction(XRD) and a superconducting quantum interference device magnetometer(SQUID). The results showed that all the compounds presented cubic Na Zn13-type structure. Their Curie temperatures changed complicatedly with decreasing Al content due to changes of antiferromagnetic and ferromagnetic interaction. Under a field change from 0 to 2 T, the maximum magnetic entropy change for La_(0.8)Ce_(0.2)Fe_(11.5)Al_(1.1)Si_(0.4), La_(0.8)Ce_(0.2)Fe_(11.5)Al_(1.0)Si_(0.5), La_(0.8)Ce_(0.2)Fe_(11.5)Al_(0.9)Si_(0.6) and La_(0.8)Ce_(0.2)Fe_(11.5)Al_(0.8)Si_(0.7) were found to be –9.6, –4.8, –5.8 and –11.7 J/(kg·K), respectively. Moreover, their hysteresis losses were 1.13 J/(kg·K) or less. The large magnetic entropy changed and small hysteresis losses made them potential candidates for practical magnetic refrigeration application.展开更多
In this paper, we first discuss the detection of supernova neutrinos on earth. Then we propose a possible method to acquire information about θ13 smaller than 1.5° by detecting the ratio of the event numbers of ...In this paper, we first discuss the detection of supernova neutrinos on earth. Then we propose a possible method to acquire information about θ13 smaller than 1.5° by detecting the ratio of the event numbers of different flavor supernova neutrinos. Such an sensitivity cannot yet be achieved by the Daya Bay reactor neutrino experiment.展开更多
The isothermal oxidation behavior of Fe-10 Al,Fe-15 Al,Fe-20 Al alloys with and without the addition of0.1 at% Y was studied at 800℃ under 1×105 Pa of flowing pure O2 for 24 h.The oxidation of three Fe-Al alloys...The isothermal oxidation behavior of Fe-10 Al,Fe-15 Al,Fe-20 Al alloys with and without the addition of0.1 at% Y was studied at 800℃ under 1×105 Pa of flowing pure O2 for 24 h.The oxidation of three Fe-Al alloys can be divided into transient state and steady state oxidation stages.The oxidation of each stage is approximately in accordance with the parabolic law.The addition of 0.1 at% Y changes the oxidation behavior obviously and leads to a significant increase of the weight gain of Fe-10 Al and Fe-15 Al.The scale grown on Fe-10 Al is much thicker and more complicated than that grown on Fe-20 Al,which is composed of an exclusive thin layer of Al2 O3 protective film.Due to the formation of a large number of nodules,the scales grown on Fe-15 AI cannot provide full protection for the alloy.Scale micro structure of the three Fe-Al-0.1 Y alloys is similar to their corresponding Fe-Al alloys.However,nodules with very small size still appear on the surface of Fe-20 Al-0.1 Y alloy.The critical Al concentration to form an exclusive Al2 O3 protective layer for Fe-Al binary alloy is on the borderline between 15 at%-20 at%.For Fe-Al-0.1 Y alloy,the presence of 20 at% Al is not enough to inhibit the growth of nodules.展开更多
We reported a quantum mechanical study of the complexes formed between Sm3+ and the bisphosphonate ligand pamidronate in aqueous solution. According to available experimental p K a values pamidronate was expected to ...We reported a quantum mechanical study of the complexes formed between Sm3+ and the bisphosphonate ligand pamidronate in aqueous solution. According to available experimental p K a values pamidronate was expected to exist in aqueous solution, at physiologically relevant p H, in its di- and tri-protonated forms(denoted by H3 L and H2L). The most stable structures of the ligands and Sm3+ complexes were found by using a detailed analysis of the conformational space with semiempirical and DFT methods. The results showed that both H2 L and H3 L bisphosphonates acted as a tridentate ligands in their complexes with Sm3+. The addition of explicit water molecules to the coordination sphere of the metal not only gave different coordination numbers for H2 L and H3 L complexes(CN=9 and 10), but also provided different trends in stabilization energies. The results highlighted the importance of considering not only an explicit first coordination shell, but also a second hydration shell, for an adequate description of this type of complexes in aqueous solution.展开更多
基金supported by the National Natural Foundation of China(40940025)National Science Foundation of Tianjin(07ZCGYSF02400,09JCYBJC07400)+2 种基金Program of China"973"(2007CB411807)Open Fund of the Key Lab of Global Change and Marine-Atmospheric Chemistry,SOA(GCMAC0806)National Natural ScienceFoundation(41006002)
文摘The sea-level change is resulted from superposition of sun, moon and other planeries, and earth itself, biological process, atmosphere and oceanography, as well as artificial actions. As a result, the sea level change is really a sensitive integral variation value of many variations, or a combined function of coupling effects of various big systems. Therefore the above mentioned superposed action of different systems and the coupling effect of sun earth and biological aspects may be called as sun earth biological coupling effect system. Based on this hypothesis, the corresponding sun dynamic, air dynamic, water dynamic and earth dynamic conceptional models are established in order to research the multiple coupling effects and feedback machsnism between these big systems. In order to determine the relations, effectness and coherent relation of different variations, the quantity, analysis is conducted through collective variation and stage division. The quantity analysis indicates that the earths spindle rotation speed is the dynamic mechanism controlling the sea level change of fluctuation. The change rate of sea level in the world is +1.32 + 0.22 mm/a, while the sea level change rate in China is only+1.39 + 0.26 mm/a in average. If take the CO2 content as the climate marker, eight cold stages (periods) are grouped out since two hundreds years AC. The extreme cold of the eighth cold stage started approximately at 1850 years AC. and if the stage from the extreme cold to extreme warm is determined as long as 200 years, the present ongoing warm stage will end at about 2050 years, there after the temperature will begin to tower. If the stage between cold and warm extremes lasts for 250 years, then the temperature will become lower at about 2100 year. Until to that time, the sea-level is estimated to raise +7 - +11 + 3.5 cm again, and there after, the sea level will begin the new lowering trend. In the same time, the climate will enter into next new cold stage subsequently.
文摘The effect of rare earth element on the solidification behavior of Al-Mg alloy was investigated in a directional solidification apparatus.It was found that during the solidification process.the rare earth element segregated in the liquid at sold-liquid interface,changed the solidification morphology and reduced the secondary arm spacing markedly.
文摘The amounts of rare earth in the solid solution in steel 16Mn were determined by means of inductive coupling plasma(ICP)spectroscopy.While the RE/S ratio was less than 1.9,the amounts of rare earth in solid solution were not more than 8 ppm,which rised slightly with the increase of the rare earth content in the steel.While the RE/S was more than 1.9,MnS disappeared completely in the steel and the amounts of rare earth in solid solution increased rapidly with the increasing of the rare earth content.The solubility of cerium in steel 16 Mn(St 52)is less than 0.011 wt% at room temperature.The results also indicate that rare earth in solid solution can reduce the amount of pearlite and increase that of ferrite and its mierohardness.The rela- tionship between microhardness(Hv)and the amount of rare earth in solid solution can be expressed by the equation of Hv=117+7 RE(ppm).
文摘The slow tensile tests,dynamic hydrogen charging tensile tests and hydrogen evolution tests after hydrogen charging were used to study the effects of rare earth metal(REM)on hydrogen behaviour in a steel 16Mn(St.52).The ratios of RE/S were chosen as 0,0.7,2.2 and 7.7,respectively.It was shown that the steel with RE/S = 2.2 give a lower hydrogen embrittlement susceptibility than others.The steels without REM can adsorb much more amount of hydrogen than that with REM under the same hydrogen charging conditions.And the amount of adsorbed hydrogen for the foriner can be evolved easier than that for the latter at room temperature,50℃ and 80℃,respectively.The experimental results were explained by the trap theory of hydrogen,the short-circuit diffusion paths in the interfaces between the elongated MnS inclusions and the matrix,and strong ability of REM to adsorb hydrogen.
文摘Optical microscope(OM),scanning electron microscope(SEM),energy dispersive spectrometer (EDS) and X-ray Diffraction(XRD) were used to study the effects of rare earth on the microstructural characteristics of 55%Al-Zn-1.6%Si hot -dip coatings on steel.The results of OM,SEM and EDS showed that by adding RE into the 55%Al-Zn-1.6%Si bath,the saw-toothed shape of intermetallic reaction layer of coating became smooth,and the thickness of the overlay and intermetallic reaction layer decreased.The XRD results revealed that the intermetallic reaction layer was comprised of two different regions,a bright phase closest to the steel substrate with phases of Fe_2Al_3 and a dark phase closest to the metallic coating with phases of FeAl_3/α-Fe-Al-Si.
文摘The total number of atmospheric particle (AP) is an important datum for planetary science and geoscience. Estimating entire AP number is also a familiar question in general physics. With standard atmosphere model, considering the number difference of AP caused by rough and uneven in the earth surface below, the sum of dry clean atmosphere particle is . So the whole number of AP including water vapor is . The rough estimation for the total number of AP on other planets (or satellites) in condensed state is also discussed on the base of it.
文摘The effect of rare earth metals(REM)on the characteristics of auto-tempering and decomposition of martensite for low-carbon and low-alloy steels(20SiMn2V and 20SiMn2VRE)was investigated using TEM,dilatometer and microhardness test.Results show that both ε.and θ carbides,during auto-tempering, may precipitate from the low-carbon martensite matrix at the same time in the 20SiMn2V steel,however,the precipitation of the ε-carbides can be inhibited by the REM contained in the 20SiMn2 VRE steel,resulting in change of the type of precipitated carbides and decrease of the extent of auto-tempering.The“in-situ”ob- servations show that the decomposition of martensite is also inhibited by the REM contained in the 20SiMn2 VRE steel during low temperature tempering.
文摘The surface functions produced by adding 14 rare earth oxides in Ni/γ Al 2O 3 system were determined by BET, gas chromatography, infrared spectroscopy, XRD, SEM, X ray electronic energy spectrum etc, and researched contrastively. The results show that the addition of rare earth oxides changes the property of catalyst surface. It is of benefit to increasing the number of active center of the catalyst and the surface acidity of the catalyst, decreasing the surface carbon deposit during the reaction. Moreover, the addition of rare earth oxides influences the electronic state of nickel atoms on the surface directly and produces electronic effect. The effect is different for each rare earth element.
文摘The effective earth radius factor(k-factor)has a refractive propagation effect on transmitted radio signals thus making its study necessary for the proper planning of terrestrial radio links and power budget.This study was carried out over the city of Lokoja,Nigeria,using ten years(2011 to 2020)atmospheric data of temperature,pressure and humidity both at the surface(12 m)and at 100 m AGL.The data were retrieved from European Centre for Medium-Range Weather Forecasts(ECMWF)ERA5.The k-factor yearly variation follows the same trend with minimum and maximum values obtained during dry and wet season months respectively.In addition,the highest mean value of 1.00042 was recorded in the month of August while the lowest value of 1.00040 was recorded in the month of January with an overall mean value of 1.0003.This value is less than the recommended standard of 1.33 by ITU-R.The propagation effect corresponding to k<1.33 is sub-refractive.The implication of this on radio wave propagation,especially terrestrial communications is that transmitted wireless signal is prone to losses.This can be mitigated through an effective power budget:Choice of transmitting antenna’s height and gain,so as to improve the Quality of Service over the study area.
基金supported by the National Science Fund,Bulgaria(Т02-22/12.12.2014)
文摘The self-healing effect of electrochemically deposited CeO2-Ce2O3 films on stainless steel OC404(SS) in 0.5 mol/L NaCl solution was studied. It was established that the corrosion potential of the steel, after covering it with CeO2-Ce2O3 layer and thermal treatment(i.e. potential of the system CeO2-Ce2O3/SSt.t.), was shifted sharply to a considerably more positive value, while the corrosion current was reduced noticeably. The X-ray photoelectron spectroscopy(XPS), energy dispersive spectroscopy(EDS) and scanning electron microscopy(SEM) analyses on the observed scratched surface area of the system CeO2-Ce2O3/SSt.t., after exposure of investigated specimens to 0.5 mol/L NaCl corrosion media, showed partial accumulation of ceria, as well as remarkable increase in the concentrations of oxides of Al, Cr and Fe, on the mechanically revealed steel surface. On the basis of the obtained results one could conclude that the secondary passive oxide/hydroxide films, formed after a definite time interval of exposure to corrosion media, acted as barriers, hindering the corrosion processes in active zones. A hypothesis was put forward about the mechanism of self-repairing oxide layers on the steel surface and their corrosion protection effect respectively.
文摘The structure, magnetic and magnetocaloric properties of the Ge-rich Gd5Ge2.05-xSi1.95-xMn2x (x=0.01 and 0.03) alloys were investigated by scanning electron microscopy, X-ray powder diffraction, differential scanning calorimeter (DSC) and magnetization measurements. The results of energy dispersive X-ray analysis (EDX) and X-ray diffraction analyses showed that the composition and crystal structure of the alloys were desired. DSC measurements were performed to determine the transformation temperatures for each alloy. Both alloys exhibited the first order phase transition around room temperature. The alloys showed an anti-ferromagnetic transition around 60 K. The isothermal magnetic entropy changes of the alloys were determined from the isothermal magnetization measurements by using the Maxwell relation. The maximum values of isothermal magnetic entropy change of the Gd5Ge2.05-xSi1.95-xMn2x alloy with x=0.01 was found to be -12.1 and -19.8 J/(kg·K) using Maxwell equation around 268 K in applied fields of 2 and 5 T, respectively.
基金Project supported by the Science and Technology Development Fund of Higher Education of Tianjin,China(20130301)the Tianjin Research Program of Application Foundation and Advanced Technology,China(14JCQNJC4000)the National Natural Science Foundation of China(11604242)
文摘The microstructure, magnetic entropy changes, hysteresis and magnetic properties of La_(0.8)Ce_(0.2)Fe_(11.5)Al_(1.5–x)Si_x(x=0.4, 0.5, 0.6, 0.7) compounds were studied by X-ray diffraction(XRD) and a superconducting quantum interference device magnetometer(SQUID). The results showed that all the compounds presented cubic Na Zn13-type structure. Their Curie temperatures changed complicatedly with decreasing Al content due to changes of antiferromagnetic and ferromagnetic interaction. Under a field change from 0 to 2 T, the maximum magnetic entropy change for La_(0.8)Ce_(0.2)Fe_(11.5)Al_(1.1)Si_(0.4), La_(0.8)Ce_(0.2)Fe_(11.5)Al_(1.0)Si_(0.5), La_(0.8)Ce_(0.2)Fe_(11.5)Al_(0.9)Si_(0.6) and La_(0.8)Ce_(0.2)Fe_(11.5)Al_(0.8)Si_(0.7) were found to be –9.6, –4.8, –5.8 and –11.7 J/(kg·K), respectively. Moreover, their hysteresis losses were 1.13 J/(kg·K) or less. The large magnetic entropy changed and small hysteresis losses made them potential candidates for practical magnetic refrigeration application.
基金Supported by National Natural Science Foundation of China (10535050,10675022)Key Project of Chinese Ministry of Education (106024)Special Grants from Beijing Normal University
文摘In this paper, we first discuss the detection of supernova neutrinos on earth. Then we propose a possible method to acquire information about θ13 smaller than 1.5° by detecting the ratio of the event numbers of different flavor supernova neutrinos. Such an sensitivity cannot yet be achieved by the Daya Bay reactor neutrino experiment.
基金Project supported by the National Natural Science Foundation of China (51701054)the Science and Technology Research Program of Jiangxi Provincial Education Department of China (GJJ160770)。
文摘The isothermal oxidation behavior of Fe-10 Al,Fe-15 Al,Fe-20 Al alloys with and without the addition of0.1 at% Y was studied at 800℃ under 1×105 Pa of flowing pure O2 for 24 h.The oxidation of three Fe-Al alloys can be divided into transient state and steady state oxidation stages.The oxidation of each stage is approximately in accordance with the parabolic law.The addition of 0.1 at% Y changes the oxidation behavior obviously and leads to a significant increase of the weight gain of Fe-10 Al and Fe-15 Al.The scale grown on Fe-10 Al is much thicker and more complicated than that grown on Fe-20 Al,which is composed of an exclusive thin layer of Al2 O3 protective film.Due to the formation of a large number of nodules,the scales grown on Fe-15 AI cannot provide full protection for the alloy.Scale micro structure of the three Fe-Al-0.1 Y alloys is similar to their corresponding Fe-Al alloys.However,nodules with very small size still appear on the surface of Fe-20 Al-0.1 Y alloy.The critical Al concentration to form an exclusive Al2 O3 protective layer for Fe-Al binary alloy is on the borderline between 15 at%-20 at%.For Fe-Al-0.1 Y alloy,the presence of 20 at% Al is not enough to inhibit the growth of nodules.
文摘We reported a quantum mechanical study of the complexes formed between Sm3+ and the bisphosphonate ligand pamidronate in aqueous solution. According to available experimental p K a values pamidronate was expected to exist in aqueous solution, at physiologically relevant p H, in its di- and tri-protonated forms(denoted by H3 L and H2L). The most stable structures of the ligands and Sm3+ complexes were found by using a detailed analysis of the conformational space with semiempirical and DFT methods. The results showed that both H2 L and H3 L bisphosphonates acted as a tridentate ligands in their complexes with Sm3+. The addition of explicit water molecules to the coordination sphere of the metal not only gave different coordination numbers for H2 L and H3 L complexes(CN=9 and 10), but also provided different trends in stabilization energies. The results highlighted the importance of considering not only an explicit first coordination shell, but also a second hydration shell, for an adequate description of this type of complexes in aqueous solution.