In view of the unclear cause of perfluorocarbons(PFCs)emission in the anode effect stage of aluminum electrolysis,the microscopic formation mechanism of PFCs was studied by density functional theory calculation and X-...In view of the unclear cause of perfluorocarbons(PFCs)emission in the anode effect stage of aluminum electrolysis,the microscopic formation mechanism of PFCs was studied by density functional theory calculation and X-ray photoelectron spectroscopy(XPS).It is found that the discharge of fluorine containing anions([F]−)on carbon anode first causes the substitution of C—H by C—F and further results in the saturation of aromatic C—C bonds,leading to the appearance of—CF_(3)or—C_(2)F_(5)group through six-carbon-ring opening.Elimination of—CF_(3)and—C_(2)F_(5) with F atom could be a likely mechanism of CF_(4) and C_(2)F_(6) formation.XPS results confirm that different types of—CF_(x) group can be formed on anode surface during electrolysis,and the possibility that[F]−discharges continuously at the C edge and finally forms different C—F bonds in quantum mechanical calculation was verified.展开更多
Lake Vrana on the island of Cres is one of the largest fresh water features on Mediterranean islands. The maximum depth of the lake is 72 m and it stores 220 million m3 of fresh water. The paper provides an overview o...Lake Vrana on the island of Cres is one of the largest fresh water features on Mediterranean islands. The maximum depth of the lake is 72 m and it stores 220 million m3 of fresh water. The paper provides an overview of lake and groundwater temperature measurements to date and recent activities within the EU project ＂CC-WaterS （Climate Change and Impacts on Water Supply）＂. Groundwater temperatures in the lake surrounding are almost constant throughout the year, in the range from 14.6 ℃ to 13.1 ℃, while thermodynamic cycle of the lake conforms to the characteristics of a monomictic, medium depth lake in the moderate climate belt. Present and future climate simulations using three limited area models were analyzed （Aladin, Promes and RegCM3）, they pointed out further air temperature increase in range of 0.27 ℃/10 yrs to 0.32 ℃/10 yrs. The significant changes of precipitation rates were not indicated. Considering increasing water consumption from the lake, already asserted negative trends, indicated climate changes and possible effects on the lake recharge, it is necessary to establish continual monitoring of parameters that describe lake system behaviour and periodically analyze lake conditions, especially with respect to the extraction for the public water supply.展开更多
It is a consensus of international community to promote the development of low carbon economy in order to face the challenges of climate change. According to the features of nuclear energy, the greenhouse gas （GHG） ...It is a consensus of international community to promote the development of low carbon economy in order to face the challenges of climate change. According to the features of nuclear energy, the greenhouse gas （GHG） emission of nuclear energy chain and other energy chain are compared and analyzed, and the results indicate that the GHG emission of nuclear power chain is the least in all types of power generation. The status of nuclear power development and the potential benefit in GHGs emission reduction by developing nuclear power in China are also analyzed. Active nuclear power development is a smart choice for constructing low-carbon energy structure and for addressing global climate changes in China.展开更多
基金the financial supports from the National Natural Science Foundation of China(Nos.51974373,51874365,62133016)the Major Scientific and Technological Innovation Projects of Shandong Province,China(No.2019JZZY020123)the Fundamental Research Funds for the Central Universities of Central South University,China(No.2019zzts242)。
文摘In view of the unclear cause of perfluorocarbons(PFCs)emission in the anode effect stage of aluminum electrolysis,the microscopic formation mechanism of PFCs was studied by density functional theory calculation and X-ray photoelectron spectroscopy(XPS).It is found that the discharge of fluorine containing anions([F]−)on carbon anode first causes the substitution of C—H by C—F and further results in the saturation of aromatic C—C bonds,leading to the appearance of—CF_(3)or—C_(2)F_(5)group through six-carbon-ring opening.Elimination of—CF_(3)and—C_(2)F_(5) with F atom could be a likely mechanism of CF_(4) and C_(2)F_(6) formation.XPS results confirm that different types of—CF_(x) group can be formed on anode surface during electrolysis,and the possibility that[F]−discharges continuously at the C edge and finally forms different C—F bonds in quantum mechanical calculation was verified.
文摘Lake Vrana on the island of Cres is one of the largest fresh water features on Mediterranean islands. The maximum depth of the lake is 72 m and it stores 220 million m3 of fresh water. The paper provides an overview of lake and groundwater temperature measurements to date and recent activities within the EU project ＂CC-WaterS （Climate Change and Impacts on Water Supply）＂. Groundwater temperatures in the lake surrounding are almost constant throughout the year, in the range from 14.6 ℃ to 13.1 ℃, while thermodynamic cycle of the lake conforms to the characteristics of a monomictic, medium depth lake in the moderate climate belt. Present and future climate simulations using three limited area models were analyzed （Aladin, Promes and RegCM3）, they pointed out further air temperature increase in range of 0.27 ℃/10 yrs to 0.32 ℃/10 yrs. The significant changes of precipitation rates were not indicated. Considering increasing water consumption from the lake, already asserted negative trends, indicated climate changes and possible effects on the lake recharge, it is necessary to establish continual monitoring of parameters that describe lake system behaviour and periodically analyze lake conditions, especially with respect to the extraction for the public water supply.
基金supported by the consulting project of Chinese Academy of Engineering entitled "The Key Issues of GHGs Emission for Different Power Energy in China"
文摘It is a consensus of international community to promote the development of low carbon economy in order to face the challenges of climate change. According to the features of nuclear energy, the greenhouse gas （GHG） emission of nuclear energy chain and other energy chain are compared and analyzed, and the results indicate that the GHG emission of nuclear power chain is the least in all types of power generation. The status of nuclear power development and the potential benefit in GHGs emission reduction by developing nuclear power in China are also analyzed. Active nuclear power development is a smart choice for constructing low-carbon energy structure and for addressing global climate changes in China.
