Lake-effect snowfall(LES)occurs when cold air moves across open lakes.LES is expected to occur more frequently over the TP,due to the intensified lake expansion caused by intensified global warming.Thus,there is an ur...Lake-effect snowfall(LES)occurs when cold air moves across open lakes.LES is expected to occur more frequently over the TP,due to the intensified lake expansion caused by intensified global warming.Thus,there is an urgent need to comprehensively assess the LES over the TP.Here,we revealed that the LES is triggered by westerly southward shift leading to the drop in air temperature and is positively correlated with lake area,wind speed and longitude across 12 large lakes(>300 km^(2))based on satellite observations and reanalysis data.Using a sensitivity model simulation,we determined that large lakes in the southern TP contributed to more than 50%of the snowfall in the downwind area in 2013.Projections indicate that the westerly-triggered LES will increase under the future RCP4.5 climate warming scenario,highlighting the importance of developing adaptive policies to address the growing risks associated with future LES.展开更多
The redox property of the ultrasmall coinage nanoclusters(with several to tens of Au/Ag atoms)has elucidated the electrontransfer capacity of nanoclusters,has been successfully utilized in a variety of redox conversio...The redox property of the ultrasmall coinage nanoclusters(with several to tens of Au/Ag atoms)has elucidated the electrontransfer capacity of nanoclusters,has been successfully utilized in a variety of redox conversions(such as from CO_(2)to CO).Nevertheless,their biological applications are mainly restricted by the scarcity of atomically precise,water-soluble metal nanoclusters,the limited application(mainly on the decomposition of H_(2)O_(2)in these days).Herein,mercaptosuccinic acid(MSA)protected ultrasmall alloy AuAg nanoclusters were prepared,the main product was determined[Au_(3)Ag_(5)(MSA)_(3)]−by electrospray ionization mass spectrometry(ESI-MS).The clusters can not only mediate the decomposition of H_(2)O_(2)to generate hydroxyl radicals,but is also able to mediate the reduction of nicotinamide adenine dinucleotide(NAD)to its reduced form of NADH.This is the first time that the atomically precise metal nanoclusters were used to mediate the coenzyme reduction.The preliminary mechanistic insights imply the reaction to be driven by the hydrogen bonding between the carboxylic groups(on the surface of MSA)and the amino N–H bonds(on NAD).In this context,the presence of the carboxylic groups,the sub-nanometer size regime(~1 nm),the synergistic effect of the Au-Ag clusters are pre-requisite to the NAD reduction.展开更多
The production of CaC2 from coke/lime powders and compressed powder pellets are low cost and fast processes. A number of studies have reported the reaction kinetics of these reactions but they are still not well under...The production of CaC2 from coke/lime powders and compressed powder pellets are low cost and fast processes. A number of studies have reported the reaction kinetics of these reactions but they are still not well understood and the proposed kinetic models are not comparable due to differences in the reaction conditions. Therefore the reaction behavior of CaO/C powders （0.074 mm） and cubes （5 mm × 5 mm × （4.6-5.1） mm） compressed from a mixture of powders have been studied using thermal gravimetric analysis （TGA） at 1700- 1850 ℃. Kinetic models were obtained from the TGA data using isoconversional and model-fitting methods. The reaction rates for the compressed feeds were lower than those for the powder feeds. This is due to the reduced surface area of the compressed samples which inhibits heat transfer from the surrounding environment （or the heating source） to the sample. The compression pressure had little influence on the reaction rate. The reaction kinetics of both the powder and the compressed feeds can be described by the contracting volume modelf（α） = 3（1 -α）^2/3, where a is the conversion rate of reactant. The apparent activation energy and pre-exponential factor of the powder feed were estimated to 346-354 kJ·mol^-1 and 5.9 x 10^7 min^-1, respectively, whereas those of the compressed feed were 305-327 kJ·mol^-1 and 3.6 ×10^6 min^-1, respectively.展开更多
基金supported by the Youth Innovation Promotion Association of Chinese Academy of Sciences(CAS2022067)the Basic Science Center for Tibetan Plateau Earth System(41988101)。
文摘Lake-effect snowfall(LES)occurs when cold air moves across open lakes.LES is expected to occur more frequently over the TP,due to the intensified lake expansion caused by intensified global warming.Thus,there is an urgent need to comprehensively assess the LES over the TP.Here,we revealed that the LES is triggered by westerly southward shift leading to the drop in air temperature and is positively correlated with lake area,wind speed and longitude across 12 large lakes(>300 km^(2))based on satellite observations and reanalysis data.Using a sensitivity model simulation,we determined that large lakes in the southern TP contributed to more than 50%of the snowfall in the downwind area in 2013.Projections indicate that the westerly-triggered LES will increase under the future RCP4.5 climate warming scenario,highlighting the importance of developing adaptive policies to address the growing risks associated with future LES.
基金National Science Foundation of Anhui Province(No.2108085J08)the University Synergy Innovation Program of Anhui Province(No.GXXT-2021-023)the technical support of high-performance computing platform of Anhui University.
文摘The redox property of the ultrasmall coinage nanoclusters(with several to tens of Au/Ag atoms)has elucidated the electrontransfer capacity of nanoclusters,has been successfully utilized in a variety of redox conversions(such as from CO_(2)to CO).Nevertheless,their biological applications are mainly restricted by the scarcity of atomically precise,water-soluble metal nanoclusters,the limited application(mainly on the decomposition of H_(2)O_(2)in these days).Herein,mercaptosuccinic acid(MSA)protected ultrasmall alloy AuAg nanoclusters were prepared,the main product was determined[Au_(3)Ag_(5)(MSA)_(3)]−by electrospray ionization mass spectrometry(ESI-MS).The clusters can not only mediate the decomposition of H_(2)O_(2)to generate hydroxyl radicals,but is also able to mediate the reduction of nicotinamide adenine dinucleotide(NAD)to its reduced form of NADH.This is the first time that the atomically precise metal nanoclusters were used to mediate the coenzyme reduction.The preliminary mechanistic insights imply the reaction to be driven by the hydrogen bonding between the carboxylic groups(on the surface of MSA)and the amino N–H bonds(on NAD).In this context,the presence of the carboxylic groups,the sub-nanometer size regime(~1 nm),the synergistic effect of the Au-Ag clusters are pre-requisite to the NAD reduction.
基金Acknowledgements Financial support from the National Basic Research Program of China （2011CB201306） and the National Natural Science Foundation of China （Grant No. 20976011） are acknowledged.
文摘The production of CaC2 from coke/lime powders and compressed powder pellets are low cost and fast processes. A number of studies have reported the reaction kinetics of these reactions but they are still not well understood and the proposed kinetic models are not comparable due to differences in the reaction conditions. Therefore the reaction behavior of CaO/C powders （0.074 mm） and cubes （5 mm × 5 mm × （4.6-5.1） mm） compressed from a mixture of powders have been studied using thermal gravimetric analysis （TGA） at 1700- 1850 ℃. Kinetic models were obtained from the TGA data using isoconversional and model-fitting methods. The reaction rates for the compressed feeds were lower than those for the powder feeds. This is due to the reduced surface area of the compressed samples which inhibits heat transfer from the surrounding environment （or the heating source） to the sample. The compression pressure had little influence on the reaction rate. The reaction kinetics of both the powder and the compressed feeds can be described by the contracting volume modelf（α） = 3（1 -α）^2/3, where a is the conversion rate of reactant. The apparent activation energy and pre-exponential factor of the powder feed were estimated to 346-354 kJ·mol^-1 and 5.9 x 10^7 min^-1, respectively, whereas those of the compressed feed were 305-327 kJ·mol^-1 and 3.6 ×10^6 min^-1, respectively.
