With the merits of high atom utilization,low cost,unique and tunable microstructures,as well as the particular catalytic behaviors,single-atom catalysts(SACs)have gained worldwide interest and achieved great advanceme...With the merits of high atom utilization,low cost,unique and tunable microstructures,as well as the particular catalytic behaviors,single-atom catalysts(SACs)have gained worldwide interest and achieved great advancements in heterogeneous catalysis recently.However,catalyzing an intricate multistep reaction is usually challenging for one single-atom center,in which case multiple catalytic sites are needed.In this review,the experimental and computational advances in the construction strategies of multi-active-site SACs will be summarized and classified as single-atom/single-atom,single-atom/nanoparticle and single-atom/support multifunctional catalysts.The microstructures of different active centers and their catalytic behaviors during catalysis will be emphatically highlighted.Moreover,the confronting challenges and opportunities of this field will be discussed.This review will place emphasis on the design of multifunctional SACs for multistep reactions,which will shed light on their further development in heterogeneous catalysis and beyond.展开更多
In this work, the reaction cross-section for neutron-induced reactions on 127I isotope was calculated using EXIFON code in the energy range of incident particle from 0 MeV to 30 MeV. The code is based on an analytical...In this work, the reaction cross-section for neutron-induced reactions on 127I isotope was calculated using EXIFON code in the energy range of incident particle from 0 MeV to 30 MeV. The code is based on an analytical model for statistical multistep direct and multistep compound reactions (SMD/SMC model). In order to see the effect of nuclear structure on cross sections, the calculation was done using nuclear shell structure effect and without considering shell structure effect. Obtained results and statistical analysis showed that shell structure effect does not give significant changes to the cross-section at considered energy ranges. This shows that EXIFON code is a good tool for investigation of nuclear reaction cross section and is useful in the production of the radioisotopes of Iodine, Antimony and tellurium of high purity and in an efficient manner using cyclotron or nuclear reactors, these isotopes have potential application for field of medical science especially for diagnostics and therapeutic purposes.展开更多
Cytochrome P450 enzymes (P450s) belong to a large family of oxidative hemeproteins and catalyze highly diverse oxygenation reactions that are involved in the biosynthesis of various natural products. Here, we report a...Cytochrome P450 enzymes (P450s) belong to a large family of oxidative hemeproteins and catalyze highly diverse oxygenation reactions that are involved in the biosynthesis of various natural products. Here, we report a multifunctional cytochrome P450 enzyme, PyrE2, which catalyzes the regioselective, successive 6-electron oxidation of an inert methyl group to produce a carboxyl product through formation of the hydroxyl and aldehyde intermediates in pyrroindomycin biosynthesis. The time-course biotransformation was characterized by the presence of the hydroxyl and aldehyde intermediates, the lag of the formation of the carboxyl product, and the subsequent loss of both intermediates, indicating that each 2-electron oxidation exhibits the distributive mechanism that requires substrate binding and product releasing. Bioinformatics analysis shows that the homologs of pyrE2 are common in the gene clusters of the spirotetronates varying in the oxidative state of the corresponding exocyclic carbon, indicating the generality and diversity of P450-catalyzed oxygenation in related biosynthetic pathways.展开更多
Precise control of each individual reaction that constitutes a multistep reaction must be performed to obtain the desired reaction product efficiently. In this work, we present a microfluidic dual loops reactor that e...Precise control of each individual reaction that constitutes a multistep reaction must be performed to obtain the desired reaction product efficiently. In this work, we present a microfluidic dual loops reactor that enables multistep reaction by integrating two identical loop reactors. Specifically, reactants A and B are synthesized in the first loop reactor and transferred to the second loop reactor to synthesize with reactant C to form the final product. These individual reactions have nano-liter volumes and are carded out in a stepwise manner in each reactor without any cross-contamination issue. To pre- cisely control the mixing efficiency in each loop reactor, we investigate the operating pressure and the operating frequency on the mixing valves for rotary mixing. This microfluidic dual loops reactor is integrated with several valves to realize the fully automated unit operation of a multistep reaction, such as metering the reactants, rotary mixing, transportation, and collecting the product. For proof of concept, CdSeZn nanopartieles are successfully synthesized in a microfluidic dual loops reactor through a fully automated mukistep reaction. Taking all of these features together, this microfluidic dual loops reactor is a general microfluidic screening platform that can synthesize various materials through a multistep reaction.展开更多
基金supported by the National Natural Science Foundation of China(22109118,21890383,21871159,22171157,22102119)the National Key R&D Program of China(2018YFA0702003)the Science and Technology Key Project of Guangdong Province of China(2020B010188002)。
文摘With the merits of high atom utilization,low cost,unique and tunable microstructures,as well as the particular catalytic behaviors,single-atom catalysts(SACs)have gained worldwide interest and achieved great advancements in heterogeneous catalysis recently.However,catalyzing an intricate multistep reaction is usually challenging for one single-atom center,in which case multiple catalytic sites are needed.In this review,the experimental and computational advances in the construction strategies of multi-active-site SACs will be summarized and classified as single-atom/single-atom,single-atom/nanoparticle and single-atom/support multifunctional catalysts.The microstructures of different active centers and their catalytic behaviors during catalysis will be emphatically highlighted.Moreover,the confronting challenges and opportunities of this field will be discussed.This review will place emphasis on the design of multifunctional SACs for multistep reactions,which will shed light on their further development in heterogeneous catalysis and beyond.
文摘In this work, the reaction cross-section for neutron-induced reactions on 127I isotope was calculated using EXIFON code in the energy range of incident particle from 0 MeV to 30 MeV. The code is based on an analytical model for statistical multistep direct and multistep compound reactions (SMD/SMC model). In order to see the effect of nuclear structure on cross sections, the calculation was done using nuclear shell structure effect and without considering shell structure effect. Obtained results and statistical analysis showed that shell structure effect does not give significant changes to the cross-section at considered energy ranges. This shows that EXIFON code is a good tool for investigation of nuclear reaction cross section and is useful in the production of the radioisotopes of Iodine, Antimony and tellurium of high purity and in an efficient manner using cyclotron or nuclear reactors, these isotopes have potential application for field of medical science especially for diagnostics and therapeutic purposes.
基金supported in part by grants from the National Key Research and Development Program of China(2022YFC2303100)the National Natural Science Foundation of China(22193070,32030002,81974495 and 21977109)the Innovative Research Team of High-Level Local Universities in Shanghai(SHSMU-ZLCX20212401).
文摘Cytochrome P450 enzymes (P450s) belong to a large family of oxidative hemeproteins and catalyze highly diverse oxygenation reactions that are involved in the biosynthesis of various natural products. Here, we report a multifunctional cytochrome P450 enzyme, PyrE2, which catalyzes the regioselective, successive 6-electron oxidation of an inert methyl group to produce a carboxyl product through formation of the hydroxyl and aldehyde intermediates in pyrroindomycin biosynthesis. The time-course biotransformation was characterized by the presence of the hydroxyl and aldehyde intermediates, the lag of the formation of the carboxyl product, and the subsequent loss of both intermediates, indicating that each 2-electron oxidation exhibits the distributive mechanism that requires substrate binding and product releasing. Bioinformatics analysis shows that the homologs of pyrE2 are common in the gene clusters of the spirotetronates varying in the oxidative state of the corresponding exocyclic carbon, indicating the generality and diversity of P450-catalyzed oxygenation in related biosynthetic pathways.
文摘Precise control of each individual reaction that constitutes a multistep reaction must be performed to obtain the desired reaction product efficiently. In this work, we present a microfluidic dual loops reactor that enables multistep reaction by integrating two identical loop reactors. Specifically, reactants A and B are synthesized in the first loop reactor and transferred to the second loop reactor to synthesize with reactant C to form the final product. These individual reactions have nano-liter volumes and are carded out in a stepwise manner in each reactor without any cross-contamination issue. To pre- cisely control the mixing efficiency in each loop reactor, we investigate the operating pressure and the operating frequency on the mixing valves for rotary mixing. This microfluidic dual loops reactor is integrated with several valves to realize the fully automated unit operation of a multistep reaction, such as metering the reactants, rotary mixing, transportation, and collecting the product. For proof of concept, CdSeZn nanopartieles are successfully synthesized in a microfluidic dual loops reactor through a fully automated mukistep reaction. Taking all of these features together, this microfluidic dual loops reactor is a general microfluidic screening platform that can synthesize various materials through a multistep reaction.
