Continuous,efficient and safe synthesis of 1-oxa-2-azaspiro[2.5]octane in a microreaction system

1-Oxa-2-azaspiro[2.5]octane,as one of N-H oxaziridines,is a selective electrophilic aminating agent for N-,S-,C-,and O-nucleophiles.It has the features of stereoselectivity and the absence of formation of strongly acidic or basic byproducts,leading to considerable interest in the development of organic synthetic methods.Currently,the economically feasible route of production of 1-oxa-2-azaspiro[2.5]octane is the reaction of cyclohexanone with ammonia and sodium hypochlorite.However,due to strong exothermic reactions,massive gas release and heterogeneous reaction,the controllability,efficiency and safety of the reaction are in great difficulty using batch technology.In this paper,a microreaction system containing predispersion,reaction and phase separation was introduced into the preparation of 1-oxa-2-azaspiro[2.5]octane.The research results showed that precise control of the process including droplet dispersion,temperature control,reaction time control and fast continuous phase separation,was the key to process intensification.Under optimal conditions,the concentration of 1-oxa-2-azaspiro[2.5]octane in product obtained by microreaciton system(~2.0 mol·L^(-1))was much higher than that obtained by batch technology(0.2-0.4 mol·L^(-1)),which demonstrated that the continuous-flow synthesis would be a more efficient substitute for batch synthesis.Meanwhile,the results of the derivation experiments also showed that the aminating agent solution with higher concentration was more advantageous in the applications.

探析异质文化背景下的中国文化推广

近年来,随着中国国国际地位显著提升,国家形象的塑造也逐渐提上日程,而在异质文化背景下如何将本民族的文化特色和文化精髓有效地传达给他国民众,则是显而易见的难题。以欧美文化为代表的西方文化与中国文化存在着显著的差异性,无论是高层的政府往来还是民间的文化交流中都存在许多误解。异质文化背景下的中国文化推广是一门需要逐步探讨的课题,试图从欧美文化的中国文化形象、异质文化传播的影响因素、以及促进异质文化背景下的中国文化推广三个角度出发,为中国良好国际形象的塑造有所助益。

Efficient production of 2′-fucosyllactose in unconventional yeast Yarrowia lipolytica

2′-Fucosyllactose(2′-FL)has great application value as a nutritional component and the whole cell biosynthesis of 2′-FL has become the focus of current research.Yarrowia lipolytica has great potential in oligosaccharide synthesis and large-scale fermentation.In this study,systematic engineering of Y.lipolytica for efficient 2′-FL production was performed.By fusing different protein tags,the synthesis of 2′-FL was optimized and the ubiquitin tag was demonstrated to be the best choice to increase the 2′-FL production.By iterative integration of the related genes,increasing the precursor supply,and promoting NADPH regeneration,the 2′-FL synthesis was further improved.The final 2′-FL titer,41.10 g/L,was obtained in the strain F5-1.Our work reports the highest 2′-FL production in Y.lipolytica,and demonstrates that Y.lipolytica is an efficient microbial chassis for the synthesis of oligosaccharides.

PI4P STimulatING innate immune activation:beyond the Golgi

The cGAS–STING pathway is pivotal for sensing cytosolic DNA[2].cGAS,a cytoplasmic DNA sensor,can be stimulated by DNA,and it consumes ATP and GTP to synthesize a second messenger,2'3'-cGAMP,which binds to STING,resulting in STING conformational change,oligomerization,and activation;ultimately,this process leads to the production of cytokines such as type I interferon to mediate antiviral and antitumor immune responses(Fig.1).Phosphoinositides,derived from phosphatidylinositol(PI),are phospholipids in membranes and are also crucial signaling molecules[3].The D-3,D-4,or D-5 positions in the inositol head group can be phosphorylated;therefore,a total of seven different PIP molecules exist in eukaryotes.Phosphatidylinositol 4-phosphate(PI4P)is distributed in various membrane components,with the highest amount in the trans-Golgi network(TGN)[4].The PI4P level in cells is regulated by its PI4K synthetases(PI4KA,PI4KB,PI4K2A,and PI4K2B)and the lipid phosphatase SAC1.In addition to being a precursor for PIP2 and PIP3,PI4P is a crucial signaling molecule involved in vesicular transport,lipid transport,and organelle morphology maintenance.

afety-reinforced rechargeable Li-CO2 battery based on a composite olid state electrolyte

The rechargeable Li-CO2 battery has been receiving significant attention owing to its merits of high energy density and the efficient utilization of CO2.However,the widely application is plagued by severe security risks,such as leakage,flammability and lithium dendrites growth due to the use of liquid organic electrolytes.Here,a composite solid state electrolyte consisting of polyethylene oxide(PEO)and 20 wt.%Li7La3Zr1.4Tao.6O12(LLZTO)was prepared and first introduced into L1-CO2 battery to solve the problems.The composite solid state electrolyte exhibited high ionic conductivity(1.03 x 10'3 S cm-1 at 70℃),wide electrochemical window(5 V vs.Li+/Li),good mechanical properties and excellent flexibility.Ultimately,the Li symmetric cell with PEO/LLZTO composite solid state electrolyte can operate 1,500 h at a current density of 0.1 mA·cm-2.The assembled all-solid-state Li-CO2 battery behaved a long cycle life of 70 cycles ata current density of 100 mA·g-1 with fixed capacity of 1,000 mAh·g^-1.Our work provides new perspective to develop rechargeable all-solid-state L1-CO2 batteries.

A highly efficient cathode catalyst γ-MnO_2@CNT composite for sodium-air batteries

The γ-MnO_2@CNT catalyst was prepared by in situ solid phase synthesis and first applied into sodium-air batteries(SABs). The initial discharge specific capacity of SABs with γ-MnO_2@CNT catalyst can reach 8804 mA h g^(-1) and the overpotential gap is only 140 m V, which is better than the batteries that is catalyzed by α-MnO_2@CNT and pure CNT. Besides, the batteries also exhibit excellent cycle performance, which can keep relatively stable for 246 cycles at 500 mA g^(-1) and 140 cycles at1000 mA g^(-1).

Cyclopropanation of active methylene compounds with β-alkoxycarbonyl vinylsulfonium salts

An efficient synthesis of β-alkoxycarbonyl vinylsulfonium salts had been developed. Their reaction with indene-1,3-diones and other active methylene compounds provided cyclopropane carboxylates in good yields. A tentative reaction mechanism was proposed.

Cycloaddition of hydrazones and 1,2-diarylalkynes promoted by t-BuOK/DMF:A convenient synthesis of tetraarylpyrazoles

A facile synthesis of tetraarylpyrazoles has been developed via t-BuOK/DMF promoted intermolecular cycloaddition of hydrazones and 1,2-diarylalkynes. A possible reaction pathway via a hydrazone radical is proposed.