The electrostatic potential energy model of hydrotalcites was based on the theory of crystallography. The anionic potential energy of MgAl-hydrotalcites, with 20 layers and 2107 anions per layer, was calculated, and t...The electrostatic potential energy model of hydrotalcites was based on the theory of crystallography. The anionic potential energy of MgAl-hydrotalcites, with 20 layers and 2107 anions per layer, was calculated, and the anionic stability of the hydrotalcites was investigated. The charge density of the layer and the distance between the adjacent anions varied with the molar ratio of Al^3＋/（Mg^2＋ ＋ Al^3＋）. Anionic potential energy depended on the charge and size of the anions. Calculation results remained consistent with thermal stability and the ion exchange ability reported. This model is able to predict anionic stability of the hydrotalcites.展开更多
The novel efficient procedure has been developed for the conjugate addition of amines to electron deficient alkenes.A series of hydrotalcite-like materials were synthesized as catalyst for the conjugate addition of am...The novel efficient procedure has been developed for the conjugate addition of amines to electron deficient alkenes.A series of hydrotalcite-like materials were synthesized as catalyst for the conjugate addition of amines and alkenes.After optimizing the reaction conditions,ZnAl-LDHs (3:1) was chosen as the best catalyst for the reaction.The results showed that the catalyst worked very well for the conjugate addition of amines to electron deficient alkenes with the excellent yields in several minutes.Operational simplicity,no solvent,low cost of the catalyst,high yields,reusability,excellent chemoselectivity,wide applicability are the key features of this method.展开更多
At the beginning of 21st century, with the rapid and steady development of China economy, a lot of large scale hydropower projects with large dams from 200 m to 300 m high are being or to be built. China dam construct...At the beginning of 21st century, with the rapid and steady development of China economy, a lot of large scale hydropower projects with large dams from 200 m to 300 m high are being or to be built. China dam constructions are reaching the level of 300 m high arch dam, 250 high CFRD (concrete face rockfill dam) and 200 m high RCC (roller compacted concrete) gravity dam. Due to the safety and the economy, the type selection for high dams has become the key issue during the argumentation for the hydropower projects, and further efforts are still needed in this aspect for high dams. After reviewing the high dam constructions in China and abroad, authors proposed some advices for the selection of dam types, and hope that it can provide some helpful information for the researches and the design of high dams.展开更多
文摘The electrostatic potential energy model of hydrotalcites was based on the theory of crystallography. The anionic potential energy of MgAl-hydrotalcites, with 20 layers and 2107 anions per layer, was calculated, and the anionic stability of the hydrotalcites was investigated. The charge density of the layer and the distance between the adjacent anions varied with the molar ratio of Al^3＋/（Mg^2＋ ＋ Al^3＋）. Anionic potential energy depended on the charge and size of the anions. Calculation results remained consistent with thermal stability and the ion exchange ability reported. This model is able to predict anionic stability of the hydrotalcites.
基金Supported by the National Key Project of Scientific and Technical Supporting Programs Funded by Ministry of Science & Technology of China (2006BAE03B06)Shanghai Leading Academic Discipline Project (B409)Shanghai International Cooperation of Science and Technology Project (06SR07101)
文摘The novel efficient procedure has been developed for the conjugate addition of amines to electron deficient alkenes.A series of hydrotalcite-like materials were synthesized as catalyst for the conjugate addition of amines and alkenes.After optimizing the reaction conditions,ZnAl-LDHs (3:1) was chosen as the best catalyst for the reaction.The results showed that the catalyst worked very well for the conjugate addition of amines to electron deficient alkenes with the excellent yields in several minutes.Operational simplicity,no solvent,low cost of the catalyst,high yields,reusability,excellent chemoselectivity,wide applicability are the key features of this method.
文摘At the beginning of 21st century, with the rapid and steady development of China economy, a lot of large scale hydropower projects with large dams from 200 m to 300 m high are being or to be built. China dam constructions are reaching the level of 300 m high arch dam, 250 high CFRD (concrete face rockfill dam) and 200 m high RCC (roller compacted concrete) gravity dam. Due to the safety and the economy, the type selection for high dams has become the key issue during the argumentation for the hydropower projects, and further efforts are still needed in this aspect for high dams. After reviewing the high dam constructions in China and abroad, authors proposed some advices for the selection of dam types, and hope that it can provide some helpful information for the researches and the design of high dams.
