By spraying concrete on inner surface,air-supported fabric structures can be used as formwork to construct reinforced concrete shell structures.The fabric formwork has the finished form of concrete structure.Large dev...By spraying concrete on inner surface,air-supported fabric structures can be used as formwork to construct reinforced concrete shell structures.The fabric formwork has the finished form of concrete structure.Large deviation from the desired shape of concrete shells still remains as central problem due to dead weight of concrete and less stiffness of fabric formwork.Polyurethane can be used not only as a bonding layer between fabrics and concrete but also as an additional stiffening layer.However,there is little research on mechanical behaviors of the polyurethane shell structure.This paper presents experimental studies on an inflated fabric model with and without polyurethane,including relief pressure tests,vertical loading tests and horizontal loading tests.Experimental results show that the additional polyurethane layer can significantly enhance the stiffness of the fabric formwork.Compared with the experiment,a numerical model using shell layered finite elements has a good prediction.The reinforcement by polyurethane to improve stiffness of air-supported fabric formwork is expected to be considered in the design and construction of the concrete shell,especially dealing with the advance of shape-control.展开更多
An asymmetric isomerization/intramolecular coupling reaction of allylic alcohols to synthesize chiral dihydrocoumarins was successfully accomplished through ruthenium catalysis.This method demonstrates a wide substrat...An asymmetric isomerization/intramolecular coupling reaction of allylic alcohols to synthesize chiral dihydrocoumarins was successfully accomplished through ruthenium catalysis.This method demonstrates a wide substrate applicability,excellent tolerance for various functional groups,and good enantioselectivities(up to 90%ee).It provides a convenient pathway to produce a diverse range ofstructurallydistinct chiral dihydrocoumarins ingoodefficiency.展开更多
Ketones are one of the most important classes of organic compounds, and widely present in various pharmacological compounds, biologically active molecules and functional materials. Over the past few decades, transitio...Ketones are one of the most important classes of organic compounds, and widely present in various pharmacological compounds, biologically active molecules and functional materials. Over the past few decades, transition metal-catalyzed conversion of aldehydes has been found to be a powerful method.With the continuous development in recent years, it has become an efficient and uncomplicated strategy for constructing ketones. There are four major mechanisms for transition metal-catalyzed ketone synthesis from aldehyde:(1) carbonyl-Heck reaction, that is 1,2-insertion of organometal species to aldehydic C=O double bond,(2) direct insertion of transition metal catalysts to aldehydic C-H bond,(3) aldehyde as acyl radical,(4) aldehyde as carbon radical acceptor. This article summarizes related reports on the transformations of aldehydes to generate corresponding ketones under different reaction conditions.展开更多
Presented herein is a facile and straightforward synthetic method for the construction of amides via Ni/NHC-catalyzed amidation of alcohols with amines. The strategy exhibits various advantages over existingmethods, i...Presented herein is a facile and straightforward synthetic method for the construction of amides via Ni/NHC-catalyzed amidation of alcohols with amines. The strategy exhibits various advantages over existingmethods, including base metal catalysis, commercially available catalyst, removal of oxidant, good yields(up to 95%), good functional group tolerance and substrate generality. Moreover, the nature of the reaction was revealed by NMR spectroscopy and isolation of intermediates.展开更多
基金Projects(51178263,51378307)supported by the National Natural Science Foundation of China
文摘By spraying concrete on inner surface,air-supported fabric structures can be used as formwork to construct reinforced concrete shell structures.The fabric formwork has the finished form of concrete structure.Large deviation from the desired shape of concrete shells still remains as central problem due to dead weight of concrete and less stiffness of fabric formwork.Polyurethane can be used not only as a bonding layer between fabrics and concrete but also as an additional stiffening layer.However,there is little research on mechanical behaviors of the polyurethane shell structure.This paper presents experimental studies on an inflated fabric model with and without polyurethane,including relief pressure tests,vertical loading tests and horizontal loading tests.Experimental results show that the additional polyurethane layer can significantly enhance the stiffness of the fabric formwork.Compared with the experiment,a numerical model using shell layered finite elements has a good prediction.The reinforcement by polyurethane to improve stiffness of air-supported fabric formwork is expected to be considered in the design and construction of the concrete shell,especially dealing with the advance of shape-control.
基金supported by the National Natural Science Foundation of China(21801206)Shaanxi Fundamental Science Research Project for Chemistry&Biology(22JHQ002)+2 种基金the Program for Young Talents of Shaanxi Province(5113190023)the Innovation Foundation for Doctor Dissertation of Northwestern Polytechnical University(CX2023104)Natural Science Basic Research Program of Shaanxi(2024JC-ZDXM-08).
文摘An asymmetric isomerization/intramolecular coupling reaction of allylic alcohols to synthesize chiral dihydrocoumarins was successfully accomplished through ruthenium catalysis.This method demonstrates a wide substrate applicability,excellent tolerance for various functional groups,and good enantioselectivities(up to 90%ee).It provides a convenient pathway to produce a diverse range ofstructurallydistinct chiral dihydrocoumarins ingoodefficiency.
基金financial support from the National Natural Science Foundation of China (No. 21801206)the Chunhui Program of Ministry of Education of China (No.5180210003)+3 种基金Program for Young Talents of Shaanxi Province (No.5113190023)the Joint Research Funds of Department of Science&Technology of Shannxi Province and Northwestern Polytechnical University (No. 2020GXLH-Z-015)the Science,Technology and Innovation Commission of Shenzhen (No. JCYJ20190809160211372)the Ao’xiang Overseas Scholars Program of NPU and the Fundamental Research Funds for the Central Universities。
文摘Ketones are one of the most important classes of organic compounds, and widely present in various pharmacological compounds, biologically active molecules and functional materials. Over the past few decades, transition metal-catalyzed conversion of aldehydes has been found to be a powerful method.With the continuous development in recent years, it has become an efficient and uncomplicated strategy for constructing ketones. There are four major mechanisms for transition metal-catalyzed ketone synthesis from aldehyde:(1) carbonyl-Heck reaction, that is 1,2-insertion of organometal species to aldehydic C=O double bond,(2) direct insertion of transition metal catalysts to aldehydic C-H bond,(3) aldehyde as acyl radical,(4) aldehyde as carbon radical acceptor. This article summarizes related reports on the transformations of aldehydes to generate corresponding ketones under different reaction conditions.
基金supported by the National Natural Science Foundation of China(21801206)the Fundamental Research Funds for the Central Universities,the Chunhui Program of Ministry of Education of China(5180210003)+2 种基金the Program for Young Talents of Shaanxi Province(5113190023)the Joint Research Funds of Department of Science&Technology of Shannxi Province and Northwestern Polytechnical University(2020GXLH-Z-015)the open research fund of Chongqing Key Laboratory of Natural Product Synthesis and Drug Research(20200004)。
文摘Presented herein is a facile and straightforward synthetic method for the construction of amides via Ni/NHC-catalyzed amidation of alcohols with amines. The strategy exhibits various advantages over existingmethods, including base metal catalysis, commercially available catalyst, removal of oxidant, good yields(up to 95%), good functional group tolerance and substrate generality. Moreover, the nature of the reaction was revealed by NMR spectroscopy and isolation of intermediates.
