By investigating 17 peptide arylthioesters that were previously challenging to produce,this study reveals a clear correlation between increased ligation activity and decreased pKa values of their corresponding arylthi...By investigating 17 peptide arylthioesters that were previously challenging to produce,this study reveals a clear correlation between increased ligation activity and decreased pKa values of their corresponding arylthiols.The observed differences are attributed to variations in thioester bond strength and steric hindrance.These insights have led to the development of an improved one-pot chemical protein synthesis approach that leverages the reactivity differences between peptide arylthioesters with C-terminal Ala-SPh(4-NO_(2))and Ala-S-Ph(2,6-diCH_(3)).This approach eliminates the need for thiol-thioester exchange and additive removal steps while enabling in situ desulfurization,thereby significantly simplifying the protein synthesis process.展开更多
Two-dimensional(2D)materials have attracted extensive attention from aerospace,integrated circuits,precision sensors,and flexible electronics due to their unique layered structure and excellent physicochemical propert...Two-dimensional(2D)materials have attracted extensive attention from aerospace,integrated circuits,precision sensors,and flexible electronics due to their unique layered structure and excellent physicochemical properties.In practice applications,the components of functional nanodevices are subjected to mechanical stress,which can affect the robust performance and structural reliability of these devices.Therefore,it is imperative to explore the mechanical properties and underlying mechanisms of 2D materials.However,researchers have an inadequate understanding of the accuracy of various in situ microscopy techniques and neglect the significance of high-quality,clean transfer techniques,resulting in deviated measurement results.There is now an urgent need to develop guidelines that allow researchers to select appropriate material transfer techniques and mechanical testing strategies based on the specific properties of 2D materials.Furthermore,the mechanical mechanism of 2D materials lacks systematic and comprehensive studies,which hinders researchers from deeply understanding the relationship between the material structure and the device performance.This work reviews the latest progress in the mechanics of 2D materials,focusing on the challenges of various transfer techniques and in situ microscopy techniques in mechanical testing,and provides effective guidance for the formulation of experimental schemes for mechanical testing.In addition,we offer detailed mechanistic insights into the fracture behavior,geometric dimension effects,edge defects,and interlayer bonding effects of 2D materials.This work is expected to advance the field development of 2D material mechanics.展开更多
This article reports the effects of Sn on the inclusions as well as the mechanical properties and hot workability of ferritic stainless steel. Precipitation phases and inclusions in Sn-bearing ferritic stainless steel...This article reports the effects of Sn on the inclusions as well as the mechanical properties and hot workability of ferritic stainless steel. Precipitation phases and inclusions in Sn-bearing ferritic stainless steel were observed, and the relationship between the workability and the microstructure of the steel was established. Energy-dispersive X-ray spectroscopic analysis of the steel reveals that an almost pure Sn phase forms and MnS-Sn compound inclusions appear in the steel with a higher Sn content. Little Sn segregation was observed in grain boundaries and in the areas around sulfide inclusions;however, the presence of Sn does not adversely affect the workability of the steel con-taining 0.4wt%Sn. When the Sn content is 0.1wt%-0.4wt%, Sn improves the tensile strength and the plastic strain ratio and also improves the plasticity with increasing temperature. A mechanism of improving the workability of ferritic stainless steel induced by Sn addition was discussed：the presence of Sn lowers the defect concentration in the ultra-pure ferritic lattice and the good distribution of tin in the lattice overcomes the problem of hot brittleness that occurs in low-carbon steel as a result of Sn segregation.展开更多
Polyion complex （PIC） micelles were spontaneously formed in aqueous solutions through electrostatic interaction between two oppositely charged block copolymers, poly（N-isopropylacrylamide）-b-poly（L-glutamic acid...Polyion complex （PIC） micelles were spontaneously formed in aqueous solutions through electrostatic interaction between two oppositely charged block copolymers, poly（N-isopropylacrylamide）-b-poly（L-glutamic acid） and poly（N-isopropylacrylamide）-b-poly（L-lysine）. Their controlled synthesis was achieved via the ring opening polymerization of N-carboxyanhydrides （NCA）, ε-benzyloxycarbonyl-L-lysine （Lys（Z）-NCA） or γ-benzyl-L-glutamate （BLG-NCA） with amino-terminated poly（N-isopropylacrylamide） macroinitiator and the subsequent deprotection reaction. The formation of PIC micelles was confirmed by dynamic light scattering and transmission electron microscopy. Turbidimetric characterization suggested that the formed PIC micelles had a concentration-dependent thermosensitivity and their phase transition behaviors could be easily adjusted either by the block length of coplymers or the concentration of micelles.展开更多
This study presents an unexpected finding that the cis isomer of β-thio-Asp exhibits higher ligation ac-tivity than the trans isomer.This discovery sheds light on the intricate nature of native chemical ligation and ...This study presents an unexpected finding that the cis isomer of β-thio-Asp exhibits higher ligation ac-tivity than the trans isomer.This discovery sheds light on the intricate nature of native chemical ligation and highlights the importance of factors beyond the steric effects of the side chain in modulating ligation activity.展开更多
Mixed redundancy strategies are generally used in cloud-based systems,with different node switch mechanisms from traditional fault-tolerant strategies.Existing studies often concentrate on optimizing a single strategy...Mixed redundancy strategies are generally used in cloud-based systems,with different node switch mechanisms from traditional fault-tolerant strategies.Existing studies often concentrate on optimizing a single strategy in cloud computing environment and ignore the impact of mixed redundancy strategies.Therefore,a model is proposed to evaluate and optimize the reliability and performance of cloud-based degraded systems subject to a mixed active and cold standby redundancy strategy.In this strategy,node switching is triggered by a continual monitoring and detection mechanism when active nodes fail.To evaluate the transient availability and the expected job completion rate of systems with such kind of strategy,a continuous-time Markov chain model is built on the state transition process and a numerical method is used to solve the model.To choose the optimal redundancy for the mixed strategy under system constraints,a greedy search algorithm is proposed after sensitivity analysis.Illustrative examples were presented to explain the process of calculating the transient probability of each system state and in turn,the availability and performance of the whole system.It was shown that the near-optimal redundancy solution could be obtained using the optimizationmethod.The comparison with optimization of the traditional mixed redundancy strategy proved that the system behavior was different using different kinds of mixed strategies and less redundancy was assigned for the new type of mixed strategy under the same system constraint.展开更多
基金CAMS Innovation Fund for Medical Sciences(CIFMS,No.2021-I2M-1-026)the National Key R&D Program of China(No.2018YFE0111400)+6 种基金the NIH Research Project Grant Program(No.R01 EB025892)the National Natural Science Foundation of China(the Training Program of the Major Research Plan,No.91853120)the National Major Scientific and Technological Special Project of China(Nos.2018ZX09711001-005 and 2018ZX09711001-013)the State Key Laboratory of Bioactive Substance and Function of Natural Medicines,Institute of Materia Medicathe Biomedical High Performance Computing Platform,Chinese Academy of Medical Sciencesthe Chinese Academy of Medical SciencesPeking Union Medical College for funding and support.
文摘By investigating 17 peptide arylthioesters that were previously challenging to produce,this study reveals a clear correlation between increased ligation activity and decreased pKa values of their corresponding arylthiols.The observed differences are attributed to variations in thioester bond strength and steric hindrance.These insights have led to the development of an improved one-pot chemical protein synthesis approach that leverages the reactivity differences between peptide arylthioesters with C-terminal Ala-SPh(4-NO_(2))and Ala-S-Ph(2,6-diCH_(3)).This approach eliminates the need for thiol-thioester exchange and additive removal steps while enabling in situ desulfurization,thereby significantly simplifying the protein synthesis process.
基金National Natural Science Foundation of China(Grant.Nos.52422505,12274124)the Shanghai Pilot Program for Basic Research(Grant.No.22TQ14001006)+2 种基金National Natural Science Foundation of China(Grant No.52275149)the Scientific Research Innovation Capability Support Project for Young Faculty(Grant No.ZYGXQNJSKYCXNLZCXM-D5)Innovative Research Group Project of the National Natural Science Foundation of China(Grant.No.52321002)。
文摘Two-dimensional(2D)materials have attracted extensive attention from aerospace,integrated circuits,precision sensors,and flexible electronics due to their unique layered structure and excellent physicochemical properties.In practice applications,the components of functional nanodevices are subjected to mechanical stress,which can affect the robust performance and structural reliability of these devices.Therefore,it is imperative to explore the mechanical properties and underlying mechanisms of 2D materials.However,researchers have an inadequate understanding of the accuracy of various in situ microscopy techniques and neglect the significance of high-quality,clean transfer techniques,resulting in deviated measurement results.There is now an urgent need to develop guidelines that allow researchers to select appropriate material transfer techniques and mechanical testing strategies based on the specific properties of 2D materials.Furthermore,the mechanical mechanism of 2D materials lacks systematic and comprehensive studies,which hinders researchers from deeply understanding the relationship between the material structure and the device performance.This work reviews the latest progress in the mechanics of 2D materials,focusing on the challenges of various transfer techniques and in situ microscopy techniques in mechanical testing,and provides effective guidance for the formulation of experimental schemes for mechanical testing.In addition,we offer detailed mechanistic insights into the fracture behavior,geometric dimension effects,edge defects,and interlayer bonding effects of 2D materials.This work is expected to advance the field development of 2D material mechanics.
基金the National Key Technology R&D Program of China(No. 2012BAE04B02)the Fundamental Research Funds for Central Universities of China(No.N130402009)+1 种基金the Natural Science Foundation of Liaoning Province of China(No. 2014020032)the Program for Liaoning Innovative Research Team in University
文摘This article reports the effects of Sn on the inclusions as well as the mechanical properties and hot workability of ferritic stainless steel. Precipitation phases and inclusions in Sn-bearing ferritic stainless steel were observed, and the relationship between the workability and the microstructure of the steel was established. Energy-dispersive X-ray spectroscopic analysis of the steel reveals that an almost pure Sn phase forms and MnS-Sn compound inclusions appear in the steel with a higher Sn content. Little Sn segregation was observed in grain boundaries and in the areas around sulfide inclusions;however, the presence of Sn does not adversely affect the workability of the steel con-taining 0.4wt%Sn. When the Sn content is 0.1wt%-0.4wt%, Sn improves the tensile strength and the plastic strain ratio and also improves the plasticity with increasing temperature. A mechanism of improving the workability of ferritic stainless steel induced by Sn addition was discussed：the presence of Sn lowers the defect concentration in the ultra-pure ferritic lattice and the good distribution of tin in the lattice overcomes the problem of hot brittleness that occurs in low-carbon steel as a result of Sn segregation.
基金financially supported by the National Natural Science Foundation of China (Nos. 20904053, 51021003,51173184)the Ministry of Science and Technology of China (International cooperation program 2011RI0001)the Program of the Science and Technology of Changchun (No. 2010061)
文摘Polyion complex （PIC） micelles were spontaneously formed in aqueous solutions through electrostatic interaction between two oppositely charged block copolymers, poly（N-isopropylacrylamide）-b-poly（L-glutamic acid） and poly（N-isopropylacrylamide）-b-poly（L-lysine）. Their controlled synthesis was achieved via the ring opening polymerization of N-carboxyanhydrides （NCA）, ε-benzyloxycarbonyl-L-lysine （Lys（Z）-NCA） or γ-benzyl-L-glutamate （BLG-NCA） with amino-terminated poly（N-isopropylacrylamide） macroinitiator and the subsequent deprotection reaction. The formation of PIC micelles was confirmed by dynamic light scattering and transmission electron microscopy. Turbidimetric characterization suggested that the formed PIC micelles had a concentration-dependent thermosensitivity and their phase transition behaviors could be easily adjusted either by the block length of coplymers or the concentration of micelles.
基金the CAMS Innovation Fund for Medical Sciences (CIFMS,No.2021-I2M-1-026)the National Key R & D Program of China (No.2018YFE0111400)+5 种基金the NIH Research Project Grant Program (No.R01 EB025892)the National Natural Science Foundation of China (the Training Program of the Major Research Plan,No.91853120)the National Major Scientific and Technological Special Project of China (Nos.2018ZX09711001-005 and 2018ZX09711001-013)the State Key Laboratory of Bioactive Substance and Function of Natural Medicines,Institute of Materia Medicathe Biomedical High Performance Computing Platform,Chinese Academy of Medical Sciences,the Chinese Academy of Medical SciencesPeking Union Medical College for funding and support
文摘This study presents an unexpected finding that the cis isomer of β-thio-Asp exhibits higher ligation ac-tivity than the trans isomer.This discovery sheds light on the intricate nature of native chemical ligation and highlights the importance of factors beyond the steric effects of the side chain in modulating ligation activity.
基金supported by the National Natural Science Foundation of China(Grant No.61309005)the Basic and Frontier Research Program of Chongqing(Grant No.cstc2014jcyj A40015)
文摘Mixed redundancy strategies are generally used in cloud-based systems,with different node switch mechanisms from traditional fault-tolerant strategies.Existing studies often concentrate on optimizing a single strategy in cloud computing environment and ignore the impact of mixed redundancy strategies.Therefore,a model is proposed to evaluate and optimize the reliability and performance of cloud-based degraded systems subject to a mixed active and cold standby redundancy strategy.In this strategy,node switching is triggered by a continual monitoring and detection mechanism when active nodes fail.To evaluate the transient availability and the expected job completion rate of systems with such kind of strategy,a continuous-time Markov chain model is built on the state transition process and a numerical method is used to solve the model.To choose the optimal redundancy for the mixed strategy under system constraints,a greedy search algorithm is proposed after sensitivity analysis.Illustrative examples were presented to explain the process of calculating the transient probability of each system state and in turn,the availability and performance of the whole system.It was shown that the near-optimal redundancy solution could be obtained using the optimizationmethod.The comparison with optimization of the traditional mixed redundancy strategy proved that the system behavior was different using different kinds of mixed strategies and less redundancy was assigned for the new type of mixed strategy under the same system constraint.
