A new chiral monomer,(S)‐5,5′‐divinyl‐BINAP,was successfully synthesized and embedded intotwo different porous organic polymers(Poly‐1and Poly‐2).After loading a Rh species,the catalystswere applied for the hete...A new chiral monomer,(S)‐5,5′‐divinyl‐BINAP,was successfully synthesized and embedded intotwo different porous organic polymers(Poly‐1and Poly‐2).After loading a Rh species,the catalystswere applied for the heterogeneous asymmetric hydroformylation of styrene.Compared with thehomogeneous BINAP analogue,the enantioselectivity of Rh/Poly‐1catalyst was drastically increasedby approximately70%.The improved enantioselectivity of the porous Rh/BINAP polymerswas attributed to the presence of flexible chiral nanopockets resulting from the increased bulk ofthe R groups near the catalytic center.展开更多
The extraction of the weakly excited anti-symmetric Lamb wave from a submerged thin spherical shell backscattering is very difficult if the carrier frequency of the incident short tone burst is not at its frequency of...The extraction of the weakly excited anti-symmetric Lamb wave from a submerged thin spherical shell backscattering is very difficult if the carrier frequency of the incident short tone burst is not at its frequency of greatest enhancement. Based on a single channel iterative time reversal technique, a method for isolating the subsonic anti-symmetric Lamb wave is proposed in this paper. The approach does not depend on the form function of a thin shell and any other priori knowledge, and it is also robust in the presence of some stochastic noise. Both theoretical and numerical results show that the subsonic anti-symmetric Lamb wave can be identified, even when the carrier frequency of the incident short tone burst is away from the frequency of greatest enhancement. The phenomenon may also be observed even in the case that the subsonic anti-symmetric Lamb wave is submerged in the noise, other than the case with the Signal to Noise Ratio being less than 10 d B, when the amplitude of the noise is comparable with the specular wave. In this paper, each iteration process contains a traditional transmission and time reversal transmission steps. The two steps can automatically compensate the time delay of the subsonic anti-symmetric Lamb wave relative to the specular wave and within-mode dispersion in the forward wave propagation.展开更多
This paper is based on previous quantum encryption proposed by researchers developing a scheme for cryptography using symmetric keys.This study has pointed out that the scheme consists of a pitfall that could lead to ...This paper is based on previous quantum encryption proposed by researchers developing a scheme for cryptography using symmetric keys.This study has pointed out that the scheme consists of a pitfall that could lead to a controlled-NOT(CNOT)extraction attack.A malicious user can obtain the secret message of a sender without being detected by using a sequence of single photons and a controlled-NOT gate.展开更多
基金supported by the Strategic priority Research Program of the Chinese Academy of Sciences (XDB17020400)~~
文摘A new chiral monomer,(S)‐5,5′‐divinyl‐BINAP,was successfully synthesized and embedded intotwo different porous organic polymers(Poly‐1and Poly‐2).After loading a Rh species,the catalystswere applied for the heterogeneous asymmetric hydroformylation of styrene.Compared with thehomogeneous BINAP analogue,the enantioselectivity of Rh/Poly‐1catalyst was drastically increasedby approximately70%.The improved enantioselectivity of the porous Rh/BINAP polymerswas attributed to the presence of flexible chiral nanopockets resulting from the increased bulk ofthe R groups near the catalytic center.
基金supported by the National Natural Science Foundation of China (46976019)the open project of the State Key Laboratory of Acoustics, Chinese Academy of Sciences (SKLA201202)
文摘The extraction of the weakly excited anti-symmetric Lamb wave from a submerged thin spherical shell backscattering is very difficult if the carrier frequency of the incident short tone burst is not at its frequency of greatest enhancement. Based on a single channel iterative time reversal technique, a method for isolating the subsonic anti-symmetric Lamb wave is proposed in this paper. The approach does not depend on the form function of a thin shell and any other priori knowledge, and it is also robust in the presence of some stochastic noise. Both theoretical and numerical results show that the subsonic anti-symmetric Lamb wave can be identified, even when the carrier frequency of the incident short tone burst is away from the frequency of greatest enhancement. The phenomenon may also be observed even in the case that the subsonic anti-symmetric Lamb wave is submerged in the noise, other than the case with the Signal to Noise Ratio being less than 10 d B, when the amplitude of the noise is comparable with the specular wave. In this paper, each iteration process contains a traditional transmission and time reversal transmission steps. The two steps can automatically compensate the time delay of the subsonic anti-symmetric Lamb wave relative to the specular wave and within-mode dispersion in the forward wave propagation.
基金supported by the Research Center of Quantum Communication and Security,National Cheng Kung University,Taiwan,China (Grant No. D100-36002)
文摘This paper is based on previous quantum encryption proposed by researchers developing a scheme for cryptography using symmetric keys.This study has pointed out that the scheme consists of a pitfall that could lead to a controlled-NOT(CNOT)extraction attack.A malicious user can obtain the secret message of a sender without being detected by using a sequence of single photons and a controlled-NOT gate.
