On 21 April 2021 local time(20 April UTC),the Indonesian Navy submarine(KRI Nanggala-402)sank near the Lombok Strait,~100 km north of the Bali Island(see magenta star in Fig.1a),with 53 crew members dead.On the basis ...On 21 April 2021 local time(20 April UTC),the Indonesian Navy submarine(KRI Nanggala-402)sank near the Lombok Strait,~100 km north of the Bali Island(see magenta star in Fig.1a),with 53 crew members dead.On the basis of Moderate Resolution Imaging Spectroradiometer(MODIS)satellite images(Jackson,2007)。展开更多
The horizontally variable density stratification and background currents are taken into the variable-coefficent extended Korteweg-de Vries(evKdV)theory to obtain the geographical and seasonal distribution of kinematic...The horizontally variable density stratification and background currents are taken into the variable-coefficent extended Korteweg-de Vries(evKdV)theory to obtain the geographical and seasonal distribution of kinematic parameters of internal solitary waves in the Andaman Sea(AS).The kinematic parameters include phase speed,dispersion parameter,quadratic and cubic nonlinear parameters.It shows that the phase speed and dispersion parameter are mainly determined by the topographic feature and have limited seasonal variation.The maximum phase speed is 2.6 m/s,which occurs in the cool season(November)in the middle of the AS,while the phase speed in the cool season is slightly larger than those in other seasons,up to 11.4%larger than that in the rainy season(July)in the southern AS.The dispersion parameter in the cool season can be 22.3%larger than that in the hot season.The nonlinear parameters have significant seasonal variation,and they can even change their signs at the continental slope in the north of the AS,from season to season.Meanwhile,the algebraic solitons dominate in the AS with minimum amplitudes(aal)ranging from 0.1 m to 102 m,and the maximum aal occurs in the cool season in the southern AS.The effect of the background flow on the parameters is also studied.The background flow has a great influence on the nonlinear parameters,e.g.,the value of cubic nonlinear parameter can be reduced by 1/3 when the background flow is not considered.展开更多
Numerous internal solitary waves(ISWs)have been observed in the southern Andaman Sea.In this study,the twodimensional Massachusetts Institute of Technology general circulation model is applied to investigate the dynam...Numerous internal solitary waves(ISWs)have been observed in the southern Andaman Sea.In this study,the twodimensional Massachusetts Institute of Technology general circulation model is applied to investigate the dynamics of ISWs and explore the effects of the bottom topography and tidal forcing on the generation and propagation of ISWs in the southern Andaman Sea.The results show that the large-amplitude depression ISWs are mainly generated via the oscillating tidal flow over the sill of the Great Channel,and the generation of ISWs is subject to the lee wave regime.The Dreadnought Bank cannot generate ISWs itself;however,it can enhance the amplitudes of eastward-propagating ISWs generated from sill A,owing to constructive interference of internal tide generation between the sill of the Great Channel and the Dreadnought Bank.The eastward-propagating ISWs generated by the eastern shallow sill near the continental shelf can propagate to the shelf,where they evolve into elevation waves because of the shallow water.Sensitivity runs show that both the semidiurnal and diurnal tides over the sill of the Great Channel can generate ISWs in this area.However,the ISWs generated by diurnal tides are much weaker than those generated by semidiurnal tides.Mixed tidal forcing has no significant effect on the generation of ISWs.展开更多
The Ritter-type reaction, without relying on a pre-installed functional group, is a highly efficient tool forthe construction of amides. However, the intrinsic chemo-selectivity that determines the generation ofamides...The Ritter-type reaction, without relying on a pre-installed functional group, is a highly efficient tool forthe construction of amides. However, the intrinsic chemo-selectivity that determines the generation ofamides or byproducts limits the efficiency and yield of the reaction. From 68 different types of hydrates,we found that a coordinatively unsaturated inorganic salt hydrate, MgSO_(4)·2H_(2)O, controlled chemoselectivity and eliminated the shortcomings of other synthesis approaches. To rationalize the differencesin selectivity of inorganic salt hydrates, we analyzed their corresponding water content, alkalinity, anions,and cations. MgSO_(4)·2H_(2)O was used with diverse scaffolds and C–H oxygenations, which demonstratedits generality in synthetic utility. Because it is readily available and it significantly improves yield, we expectthat MgSO_(4)·2H_(2)O will have broad application for Ritter-type reactions.展开更多
基金The Key Research Program of Frontier SciencesChinese Academy of Sciences(CAS)under contract No.QYZDJSSW-DQC034+6 种基金the fund of Southern Marine Science and Engineering Guangdong Laboratory(Guangzhou)under contract No.GML2019ZD0304the National Natural Science Foundation of China under contract Nos 41521005,41776007,41776008 and 91858201the fund of Chinese Academy of Sciences under contract No.ISEE2021PY01the Youth Science and Technology Innovation Talent of Guangdong Te Zhi Plan under contract No.2019TQ05H519the Rising Star Foundation of SCSIO under contract No.NHXX2019WL0201the Natural Science Foundation of Guangdong Province under contract Nos 2020A1515010495,2021A1515012538 and 2021A1515011613the Youth Innovation Promotion Association from CAS under contract No.2018378。
文摘On 21 April 2021 local time(20 April UTC),the Indonesian Navy submarine(KRI Nanggala-402)sank near the Lombok Strait,~100 km north of the Bali Island(see magenta star in Fig.1a),with 53 crew members dead.On the basis of Moderate Resolution Imaging Spectroradiometer(MODIS)satellite images(Jackson,2007)。
基金The Key Research Program of Frontier SciencesChinese Academy of Sciences under contract No.QYZDJ-SSWDQC034+9 种基金the Grant from Southern Marine Science and Engineering Guangdong Laboratory(Guangzhou)under contract No.GML2019ZD0304the National Natural Science Foundation of China under contract Nos 41521005,41776007 and 41776008the Guangdong Natural Science Foundation under contract No.2020A1515010495the Grant from Chinese Academy of Sciences under contract No.ISEE2021PY01the Guangzhou Science and Technology Program under contract No.201804010373the Youth Science and Technology Innovation Talent of Guangdong Te Zhi Plan under contract No.2019TQ05H519the Pearl River S&T Nova Program of Guangzhou under contract No.201806010091the Rising Star Foundation of South China Sea Institute of Oceanology under contract No.NHXX2019WL0201the Youth Innovation Promotion Association of Chinese Academy of Sciences under contract No.2018378the State Key Laboratory of Tropical Oceanolography Independent Research Program under contract No.LTOZZ2001。
文摘The horizontally variable density stratification and background currents are taken into the variable-coefficent extended Korteweg-de Vries(evKdV)theory to obtain the geographical and seasonal distribution of kinematic parameters of internal solitary waves in the Andaman Sea(AS).The kinematic parameters include phase speed,dispersion parameter,quadratic and cubic nonlinear parameters.It shows that the phase speed and dispersion parameter are mainly determined by the topographic feature and have limited seasonal variation.The maximum phase speed is 2.6 m/s,which occurs in the cool season(November)in the middle of the AS,while the phase speed in the cool season is slightly larger than those in other seasons,up to 11.4%larger than that in the rainy season(July)in the southern AS.The dispersion parameter in the cool season can be 22.3%larger than that in the hot season.The nonlinear parameters have significant seasonal variation,and they can even change their signs at the continental slope in the north of the AS,from season to season.Meanwhile,the algebraic solitons dominate in the AS with minimum amplitudes(aal)ranging from 0.1 m to 102 m,and the maximum aal occurs in the cool season in the southern AS.The effect of the background flow on the parameters is also studied.The background flow has a great influence on the nonlinear parameters,e.g.,the value of cubic nonlinear parameter can be reduced by 1/3 when the background flow is not considered.
基金supported by the Key Research Program of Frontier Sciences,Chinese Academy of Sciences(Grant No.QYZDJ-SSW-DQC034)the Southern Marine Science and Engineering Guangdong Laboratory(Guangzhou)(Grant No.GML2019ZD0304)+8 种基金the National Natural Science Foundation of China(Nos.41521005,41776007 and 41776008)the Chinese Academy of Sciences(Grant No.ISEE2021-PY01)the Guangzhou Science and Technology Program(Grant No.201804010373)the Guangdong Natural Science Foundation(Grant No.2020A1514010495)the Youth Science and Technology Innovation Talent of Guangdong TeZhi Plan(Grant No.2019TQ05H519)the Pearl River S&T Nova Program of Guangzhou(Grant No.201806010091)the Youth Innovation Promotion Association of CAS(Grant No.2018378)the LTO Independent Research Program(Grant No.LTOZZ2001)the Rising Star Foundation of SCSIO(Grant No.NHXX2019WL0201).
文摘Numerous internal solitary waves(ISWs)have been observed in the southern Andaman Sea.In this study,the twodimensional Massachusetts Institute of Technology general circulation model is applied to investigate the dynamics of ISWs and explore the effects of the bottom topography and tidal forcing on the generation and propagation of ISWs in the southern Andaman Sea.The results show that the large-amplitude depression ISWs are mainly generated via the oscillating tidal flow over the sill of the Great Channel,and the generation of ISWs is subject to the lee wave regime.The Dreadnought Bank cannot generate ISWs itself;however,it can enhance the amplitudes of eastward-propagating ISWs generated from sill A,owing to constructive interference of internal tide generation between the sill of the Great Channel and the Dreadnought Bank.The eastward-propagating ISWs generated by the eastern shallow sill near the continental shelf can propagate to the shelf,where they evolve into elevation waves because of the shallow water.Sensitivity runs show that both the semidiurnal and diurnal tides over the sill of the Great Channel can generate ISWs in this area.However,the ISWs generated by diurnal tides are much weaker than those generated by semidiurnal tides.Mixed tidal forcing has no significant effect on the generation of ISWs.
基金support from the Research Foundation for Talented Scholars of Fujian Medical University(grant number:XRCZX2018014)the Joint Funds for the Innovation of Science and Technology,Fujian province(grant number:2018Y9072)the Natural Science Foundation of Fujian Province,China(grant number:2021J01693).
文摘The Ritter-type reaction, without relying on a pre-installed functional group, is a highly efficient tool forthe construction of amides. However, the intrinsic chemo-selectivity that determines the generation ofamides or byproducts limits the efficiency and yield of the reaction. From 68 different types of hydrates,we found that a coordinatively unsaturated inorganic salt hydrate, MgSO_(4)·2H_(2)O, controlled chemoselectivity and eliminated the shortcomings of other synthesis approaches. To rationalize the differencesin selectivity of inorganic salt hydrates, we analyzed their corresponding water content, alkalinity, anions,and cations. MgSO_(4)·2H_(2)O was used with diverse scaffolds and C–H oxygenations, which demonstratedits generality in synthetic utility. Because it is readily available and it significantly improves yield, we expectthat MgSO_(4)·2H_(2)O will have broad application for Ritter-type reactions.