Skipped dienes are of great importance but remain challenging to synthesize because of the presence of a sp hybrid carbon between the two alkenes.Herein,we have developed the first nickel-catalyzed regio-,(E)-stereo-a...Skipped dienes are of great importance but remain challenging to synthesize because of the presence of a sp hybrid carbon between the two alkenes.Herein,we have developed the first nickel-catalyzed regio-,(E)-stereo-and linear-selective ring-opening/cross-coupling reaction of vinylaziridines with organoboronic acids under mild conditions to construct various skipped aminodienes.The reaction exhibits wide functional-group compatibility,and could be adapted for the introduction of skipped aminodiene functionality into bioactive molecules.展开更多
It is proved that for matrices A,B in the n by n upper triangular matrix ring T_(n)(R)over a domain R,if AB is nonzero and central in T_(n)(R)then AB=BA.The n by n full matrix rings over right Noetherian domains are a...It is proved that for matrices A,B in the n by n upper triangular matrix ring T_(n)(R)over a domain R,if AB is nonzero and central in T_(n)(R)then AB=BA.The n by n full matrix rings over right Noetherian domains are also shown to have this property.In this article we treat a ring property that is a generalization of this result,and a ring with such a property is said to be weakly reversible-over-center.The class of weakly reversible-over-center rings contains both full matrix rings over right Noetherian domains and upper triangular matrix rings over domains.The structure of various sorts of weakly reversible-over-center rings is studied in relation to the questions raised in the process naturally.We also consider the connection between the property of being weakly reversible-over-center and the related ring properties.展开更多
为了解决高温高压天然气井管柱泄漏问题,国内油气田使用了多种特殊螺纹油套管,但井筒密封性仍然无法得到保障。现行的接头密封面接触压应力设计法不能有效堵塞密封结构的泄漏通道,亟待研究发展石油专用管密封设计方法和密封技术。为此,...为了解决高温高压天然气井管柱泄漏问题,国内油气田使用了多种特殊螺纹油套管,但井筒密封性仍然无法得到保障。现行的接头密封面接触压应力设计法不能有效堵塞密封结构的泄漏通道,亟待研究发展石油专用管密封设计方法和密封技术。为此,在密封面压应力设计基础上,提出增加弹性应变设计,并实验验证技术有效性。研究结果表明:①采用弹性材料实现弹性应变密封设计,通过材料的应力应变循环试验,优选出弹性应变达到6%的超弹性合金Ti-Ni-X;②设计的多种密封结构使密封面产生足够大弹性应变,以堵塞接头在工厂制造或井下服役期间形成的泄漏通道;③研发出一种密封环超弹性应变密封套管,样品成功通过了上卸扣试验和API RP 5C5 CAL IV级B系列密封试验,最大试验载荷达到了95%管体应力包罗线,最大试验温度达到180℃。结论认为,超弹性应变密封新技术可作为新一代石油专用管及井口管件密封的技术储备,该技术有望提高气井管柱和井口管件的密封性。展开更多
基金the funding support of this work by the National Natural Science Foundation of China(Nos.21831005 and 21991112)National Key R&D Program of China(No.2018YFE0126800).
文摘Skipped dienes are of great importance but remain challenging to synthesize because of the presence of a sp hybrid carbon between the two alkenes.Herein,we have developed the first nickel-catalyzed regio-,(E)-stereo-and linear-selective ring-opening/cross-coupling reaction of vinylaziridines with organoboronic acids under mild conditions to construct various skipped aminodienes.The reaction exhibits wide functional-group compatibility,and could be adapted for the introduction of skipped aminodiene functionality into bioactive molecules.
基金The second author was supported by the National Natural Science Foundation of China(11361063)the third author was supported by Basic Science Research Program through the National Research Foundation of Korea(NRF)funded by the Ministry of Education of Korea(2016R1D1A1B03931190).
文摘It is proved that for matrices A,B in the n by n upper triangular matrix ring T_(n)(R)over a domain R,if AB is nonzero and central in T_(n)(R)then AB=BA.The n by n full matrix rings over right Noetherian domains are also shown to have this property.In this article we treat a ring property that is a generalization of this result,and a ring with such a property is said to be weakly reversible-over-center.The class of weakly reversible-over-center rings contains both full matrix rings over right Noetherian domains and upper triangular matrix rings over domains.The structure of various sorts of weakly reversible-over-center rings is studied in relation to the questions raised in the process naturally.We also consider the connection between the property of being weakly reversible-over-center and the related ring properties.
文摘为了解决高温高压天然气井管柱泄漏问题,国内油气田使用了多种特殊螺纹油套管,但井筒密封性仍然无法得到保障。现行的接头密封面接触压应力设计法不能有效堵塞密封结构的泄漏通道,亟待研究发展石油专用管密封设计方法和密封技术。为此,在密封面压应力设计基础上,提出增加弹性应变设计,并实验验证技术有效性。研究结果表明:①采用弹性材料实现弹性应变密封设计,通过材料的应力应变循环试验,优选出弹性应变达到6%的超弹性合金Ti-Ni-X;②设计的多种密封结构使密封面产生足够大弹性应变,以堵塞接头在工厂制造或井下服役期间形成的泄漏通道;③研发出一种密封环超弹性应变密封套管,样品成功通过了上卸扣试验和API RP 5C5 CAL IV级B系列密封试验,最大试验载荷达到了95%管体应力包罗线,最大试验温度达到180℃。结论认为,超弹性应变密封新技术可作为新一代石油专用管及井口管件密封的技术储备,该技术有望提高气井管柱和井口管件的密封性。
