Oxygen isotope fractionation between coexisting minerals in slowly cooled rocks conveys information about their cooling history. By using the fast grain boundary(FGB) model to simulate closed-system diffusive exchange...Oxygen isotope fractionation between coexisting minerals in slowly cooled rocks conveys information about their cooling history. By using the fast grain boundary(FGB) model to simulate closed-system diffusive exchange of oxygen isotopes between coexisting minerals, I show that the apparent equilibrium temperatures(Tae) by the mineral pair with the largest isotopic fractionation(PLIF) always lies between the closure temperatures(Tc) of those two minerals. Therefore, when the rate of oxygen diffusion and hence Tc for the PLIF chance to be comparable(such as in the case of quartz and magnetite), Tae will serve as a good approximation of Tc regardless of variation in mineral proportions. The specialty of the PLIF in constraining Tae within their Tc range can be generalized to other stable isotope systems and element partitioning. By approximating Tc with Tae and inverting Dodson's equation, the cooling rate of plutonic or metamorphic rocks can be inferred.展开更多
TiClx （x=2.17） was prepared by using titanium sponge to reduce the concentration of TiCl4 in a NaCl-KCl melt under negative pressure. The as-prepared NaCl-KCl-TiClx melt was employed as the electrolyte, and two para...TiClx （x=2.17） was prepared by using titanium sponge to reduce the concentration of TiCl4 in a NaCl-KCl melt under negative pressure. The as-prepared NaCl-KCl-TiClx melt was employed as the electrolyte, and two parallel crude titanium plates and one high-purity titanium plate were used as the anode and cathode, respectively. A series of electrochemical tests were performed to investigate the influence of electrolytic parameters on the current efficiency and quality of cathodic products. The results indicated that the quality of cathodic products was related to the current efficiency, which is significantly dependent on the current density and the initial concentration of titanium ions. The significance of this study is the attainment of high-purity titanium with a low oxygen content of 30× 10^-6.展开更多
Thimble zirconia oxygen sensors were prepared with yttria stabilized zirconia(YSZ). The surfaces of the electrode, electrolyte and their interface were observed by scanning electron microscope(SEM). The sensor was exa...Thimble zirconia oxygen sensors were prepared with yttria stabilized zirconia(YSZ). The surfaces of the electrode, electrolyte and their interface were observed by scanning electron microscope(SEM). The sensor was examined with engine bench test to evaluate the essential performance. The results show that the oxygen sensor has good performance, which can meet the demand of practical applications. Chemical equilibrium theory was introduced to explain electromotive force of the sensors and the influence of temperature on the signals. The educed theoretical model of electromotive force agrees well with testing results.展开更多
Oxygen isotope fractionation is studied during the synthesis of kaolinite under controlled conditions of temperature and time. Equilibrium conditions have been established and its relationship with temperature has bee...Oxygen isotope fractionation is studied during the synthesis of kaolinite under controlled conditions of temperature and time. Equilibrium conditions have been established and its relationship with temperature has been studied. Kaolinite was hydrothermally precipitated starting from non-crystalline aluminosilicate gels. The amount of kaolinite obtained increases up to a limited constant value and in all cases coexists with the amorphous starting gels. It can be seen that the data obtained at 48 hours of synthesis can be considered as quasi-equilibrium, since the total isotopic equilibrium has not been reached, only the sample obtained at 24 hours should be discarded for studies in equilibrium. This would allow us, with the samples obtained at 720 hours, to try to establish a relationship between isotopic fractionation and temperature, provided that we know the water in equilibrium with the synthesized kaolinite. Two equations have been obtained that show correlation coefficients with a high statistical significance.展开更多
The effect of thermal oxidation of activated carbon surface on its adsorption of dibenzothiophene was investigated.The surface oxidation of the activated carbon was carried out by heating at different temperatures in ...The effect of thermal oxidation of activated carbon surface on its adsorption of dibenzothiophene was investigated.The surface oxidation of the activated carbon was carried out by heating at different temperatures in the air.Static equilibrium adsorption experiments were conducted to determine the isotherms of dibenzothiophene on the original and oxidized activated carbons.The type and concentration of oxygen functional groups on the activated carbons were determined by diffuse reflectance infrared Fourier transform spectroscopy(DRIFTS)and Boehm titration respectively.The influence of the surface chemistry of the activated carbons on the adsorption capacity for dibenzothiophene was discussed.The results showed that the acid oxygen-containing groups of the activated carbon surfaces played an important role in enhancing the adsorption of dibenzothiophene.It was shown that the use of thermal oxidation could increase the concentration of oxygen-containing groups on the activated carbon surfaces,and consequently increase its adsorption capacity for dibenzothiophene.It was also found that the higher the oxidation temperature,the more the oxygen-containing groups on activated carbon surface,which enhanced the adsorption capacity of dibenzothiophene on its surfaces.The Langmuir equation was shown to fit well these isotherms.展开更多
基金the financial support from the Recruitment Program of Global Experts(Thousand Talents),Chinathe Natural Science Foundation of China(41322015)
文摘Oxygen isotope fractionation between coexisting minerals in slowly cooled rocks conveys information about their cooling history. By using the fast grain boundary(FGB) model to simulate closed-system diffusive exchange of oxygen isotopes between coexisting minerals, I show that the apparent equilibrium temperatures(Tae) by the mineral pair with the largest isotopic fractionation(PLIF) always lies between the closure temperatures(Tc) of those two minerals. Therefore, when the rate of oxygen diffusion and hence Tc for the PLIF chance to be comparable(such as in the case of quartz and magnetite), Tae will serve as a good approximation of Tc regardless of variation in mineral proportions. The specialty of the PLIF in constraining Tae within their Tc range can be generalized to other stable isotope systems and element partitioning. By approximating Tc with Tae and inverting Dodson's equation, the cooling rate of plutonic or metamorphic rocks can be inferred.
基金the National Science Foundation of China(Nos.50934001 and 51322402)the National High-Tech Research and Development Program of China (No.2012AA062302)+2 种基金the Program of the Co-construction with Beijing Municipal Commission of Education of China (Nos.00012047 and 00012085)the Program for New Century Excellent Talents in Universities(NCET-11-0577)the Fundamental Research Funds for the Central Universities(No.FRF-AS-11-003A)
文摘TiClx （x=2.17） was prepared by using titanium sponge to reduce the concentration of TiCl4 in a NaCl-KCl melt under negative pressure. The as-prepared NaCl-KCl-TiClx melt was employed as the electrolyte, and two parallel crude titanium plates and one high-purity titanium plate were used as the anode and cathode, respectively. A series of electrochemical tests were performed to investigate the influence of electrolytic parameters on the current efficiency and quality of cathodic products. The results indicated that the quality of cathodic products was related to the current efficiency, which is significantly dependent on the current density and the initial concentration of titanium ions. The significance of this study is the attainment of high-purity titanium with a low oxygen content of 30× 10^-6.
文摘Thimble zirconia oxygen sensors were prepared with yttria stabilized zirconia(YSZ). The surfaces of the electrode, electrolyte and their interface were observed by scanning electron microscope(SEM). The sensor was examined with engine bench test to evaluate the essential performance. The results show that the oxygen sensor has good performance, which can meet the demand of practical applications. Chemical equilibrium theory was introduced to explain electromotive force of the sensors and the influence of temperature on the signals. The educed theoretical model of electromotive force agrees well with testing results.
文摘Oxygen isotope fractionation is studied during the synthesis of kaolinite under controlled conditions of temperature and time. Equilibrium conditions have been established and its relationship with temperature has been studied. Kaolinite was hydrothermally precipitated starting from non-crystalline aluminosilicate gels. The amount of kaolinite obtained increases up to a limited constant value and in all cases coexists with the amorphous starting gels. It can be seen that the data obtained at 48 hours of synthesis can be considered as quasi-equilibrium, since the total isotopic equilibrium has not been reached, only the sample obtained at 24 hours should be discarded for studies in equilibrium. This would allow us, with the samples obtained at 720 hours, to try to establish a relationship between isotopic fractionation and temperature, provided that we know the water in equilibrium with the synthesized kaolinite. Two equations have been obtained that show correlation coefficients with a high statistical significance.
文摘The effect of thermal oxidation of activated carbon surface on its adsorption of dibenzothiophene was investigated.The surface oxidation of the activated carbon was carried out by heating at different temperatures in the air.Static equilibrium adsorption experiments were conducted to determine the isotherms of dibenzothiophene on the original and oxidized activated carbons.The type and concentration of oxygen functional groups on the activated carbons were determined by diffuse reflectance infrared Fourier transform spectroscopy(DRIFTS)and Boehm titration respectively.The influence of the surface chemistry of the activated carbons on the adsorption capacity for dibenzothiophene was discussed.The results showed that the acid oxygen-containing groups of the activated carbon surfaces played an important role in enhancing the adsorption of dibenzothiophene.It was shown that the use of thermal oxidation could increase the concentration of oxygen-containing groups on the activated carbon surfaces,and consequently increase its adsorption capacity for dibenzothiophene.It was also found that the higher the oxidation temperature,the more the oxygen-containing groups on activated carbon surface,which enhanced the adsorption capacity of dibenzothiophene on its surfaces.The Langmuir equation was shown to fit well these isotherms.
