A repeated sequence DNA fragment, L5B-4, was cloned from the 5 kb BamHI DNA fragments of rat genomic DNA. The expressions of the L5B-4 DNA fragment are different in liver and hepatoma cells. The amounts of transcripts...A repeated sequence DNA fragment, L5B-4, was cloned from the 5 kb BamHI DNA fragments of rat genomic DNA. The expressions of the L5B-4 DNA fragment are different in liver and hepatoma cells. The amounts of transcripts in hepatoma cells are lower in nucleus and higher in cytoplasm, especially in polysomal RNA, as compared with that in liver cells. The alteration shown in polysomal RNA of hepatoma cells seems to be specific. These results are discussed with respect to the possible function of this repeated DNA and its variation in hepatoma cells.展开更多
Graphitic carbon nitride(g-C_(3)N_(4))has attracted great interest in photocatalysis and photoelectrocatalysis.However,their poor hydrophilicity poses a great challenge for their applications in aqueous environment.He...Graphitic carbon nitride(g-C_(3)N_(4))has attracted great interest in photocatalysis and photoelectrocatalysis.However,their poor hydrophilicity poses a great challenge for their applications in aqueous environment.Here,we demonstrate synthesis of a hydrophilic bi-functional hierarchical architecture by the assembly of B-doped g-C_(3)N_(4)nanoplatelets.Such hierarchical B-doped g-C_(3)N_(4)material enables full utilization of their highly enhanced visible light absorption and photogenerated carrier separation in aqueous medium,leading to an excellent photocatalytic H_(2)O_(2)production rate of 4240.3μM g^(-1)h^(-1),2.84,2.64 and 2.13 times higher than that of the bulk g-C_(3)N_(4),g-C_(3)N_(4)nanoplatelets and bulk B doped g-C_(3)N_(4),respectively.Photoanodes based on these hierarchical architectures can generate an unprecedented photocurrent density of 1.72 m A cm^(-2)at 1.23 V under AM 1.5 G illumination for photoelectrochemical water splitting.This work makes a fundamental improvement towards large-scale exploitation of highly active,hydrophilic and stable metal-free g-C_(3)N_(4)photocatalysts for various practical applications.展开更多
1 INTRODUCTIONThe determination of the solids hold-up and local solidfluxes is of paramount importance in the study ofthe hydrodynamics of a two-phase flow.Several tech-niques have been used during the past decades(Ta...1 INTRODUCTIONThe determination of the solids hold-up and local solidfluxes is of paramount importance in the study ofthe hydrodynamics of a two-phase flow.Several tech-niques have been used during the past decades(Table1).These methods can be classified in two groups,depending on their possible disturbance of the two-展开更多
Enhancing the light olefin selectivity and extending the catalytic durability remain critical challenges for ZSM-5 zeolites in the methanol to olefins(MTO)conversion,while the inherent diffusion restriction along the ...Enhancing the light olefin selectivity and extending the catalytic durability remain critical challenges for ZSM-5 zeolites in the methanol to olefins(MTO)conversion,while the inherent diffusion restriction along the MFI b-axis direction and poor coke accommodation are the main limiting factors.In this work,we developed a hierarchically singlecrystalline ZSM-5 sheet architecture that features an interconnected multiscale porosity and a remarkably reduced baxis thickness(<50 nm),as quantitatively verified by threedimensional(3D)electron tomography.Real-time confocal laser scanning microscopy(CLSM)tracking demonstrated a significant enhancement in molecular diffusivity compared to conventional micron-sized ZSM-5 counterparts(Micro-ZSM5).This engineered structure allows abundant aluminum sites to be distributed on the highly accessible diffusion pathways,and displays an enlarged coke accommodation of 16.31 wt%with a coke deposition rate of 0.59 mg g^(-1) h^(-1),which was only one third of that in the Micro-ZSM-5.In a continuous MTO process,this novel hierarchical ZSM-5 sheet(Hier-ZSM-5-S)kept an average selectivity to ethylene and propene of 63.5%on stream for 22.2 h(WHSV=3.6 h−1,T=480℃),which was 19%higher and 6.5 times longer than those of Micro-ZSM-5,respectively.This hierarchically shortened b-axis structure establishes a generalizable paradigm for enhanced diffusion and coke accommodation in a precisely designed pore system,which is expected to be adjusted and applied for varying reactions.展开更多
A high-Mn austenitic steel Fe-14Cr-12Ni-10Mn-3Cu-2.5Al-1Nb was tested at 500℃in static Pb-Bi eutectic for 10000 h.In the course of the test,oxygen concentration in liquid metal was cycled from~10^(-6) to~10^(-9) mass...A high-Mn austenitic steel Fe-14Cr-12Ni-10Mn-3Cu-2.5Al-1Nb was tested at 500℃in static Pb-Bi eutectic for 10000 h.In the course of the test,oxygen concentration in liquid metal was cycled from~10^(-6) to~10^(-9) mass%,which provides oxidation and dissolution regimes,respectively.After 10000 h exposure steel showed formation of ferrite corrosion zone depleted in Mn,Ni,Cu,Cr,Fe and penetrated by Pb and Bi.Average depth of corrosion is 15±5μm,while maximum corrosion depth locally reaches~35μm.Dissolved Mn and Cr re-precipitated in the vicinity of steel surface in a form of stratified Mn-O/Cr-Mn-O oxide scale.Obtained results were compared to those of similar Al-alloyed austenitic steels with lower Mn content,which exhibited protective oxidation under same test conditions.The phenomenological mechanism of oxygen-driven de-alloying of steel in Pb-Bi[O]is discussed.展开更多
激光定向能量沉积(laser directed energy deposition,LDED)凭借高效率与工艺柔性,正成为解决室温高脆性和高活性的TiAl4822(Ti-48Al-2Cr-2Nb)合金传统工艺难加工、难制备大型复杂构件问题的关键途径,以充分发挥其航空发动机等高温轻质...激光定向能量沉积(laser directed energy deposition,LDED)凭借高效率与工艺柔性,正成为解决室温高脆性和高活性的TiAl4822(Ti-48Al-2Cr-2Nb)合金传统工艺难加工、难制备大型复杂构件问题的关键途径,以充分发挥其航空发动机等高温轻质部件的理想材料潜力。然而,LDED过程中快速熔融-凝固循环会产生极大的温度梯度和残余应力,从而导致构件开裂,但目前尚无成熟手段能够完全抑制裂纹产生。本工作利用整体高温辅助LDED制备出30 mm×25 mm×6 mm致密无裂纹的TiAl4822合金薄壁构件,并对其宏观形貌、微观组织、孔隙率及显微硬度进行研究。研究结果表明:在常温条件下,LDED制备的TiAl4822合金薄壁样件易发生以解理为主的脆性断裂,显微组织以细小等轴晶为主;引入800℃整体高温辅助后,沉积层晶粒定向生长为自下而上倾斜的柱状晶,孔隙率从0.05%降至0.008%,孔径分布更均匀,表面未见宏观裂纹;与此同时,显微硬度由常温样件的390.46HV_(0.2)降至354.94HV_(0.2),这主要归因于在高温辅助条件下晶粒长大、晶界减少及析出相中γ相的含量相对增加。因此,整体高温辅助不仅有效抑制裂纹与大尺寸孔隙的产生,还优化微观组织均匀性,为TiAl4822合金的高致密、高性能制备提供新途径。展开更多
Peptides play important roles in chemistry,medicinal chemistry and life science,due to their high efficiency and specificity,unusual biological and therapeutic properties.As naturally occurring peptides often face wit...Peptides play important roles in chemistry,medicinal chemistry and life science,due to their high efficiency and specificity,unusual biological and therapeutic properties.As naturally occurring peptides often face with their intrinsic limitations including metabolic instability and low membrane permeability,the strategies for synthesizing unnatural amino acids and peptides are explored.Among the methods for modifying amino acids and peptides,chemo-and site-selective approaches are preferred because of the ability to fine-tuning structural features.Recently,transition metal-catalyzed Csingle bondH activation has been employed for the functionalization of amino acids and peptides.Through domino Csingle bondH activation/annulation,a series of structurally complex and diverse amino acids and peptides is constructed.This review highlights recent advances in the synthesis of unnatural amino acids and peptides via transition metal-catalyzed Csingle bondH activation/annulation.展开更多
To enhance the anti-resistance efficacy of our previously disclosed naphthyl-triazine 5,structure-based drug design strategy was rationally conducted to design a series of novel biphenyl-piperidine-triazinecontaining ...To enhance the anti-resistance efficacy of our previously disclosed naphthyl-triazine 5,structure-based drug design strategy was rationally conducted to design a series of novel biphenyl-piperidine-triazinecontaining non-nucleoside reverse transcriptase inhibitors.Remarkably,several of these compounds demonstrated single-digit nanomolar antiviral potency against both wild-type(WT)human immunodeficiency virus-1(HIV-1)and five clinically relevant mutant strains.Among these,compound 11s emerged as the most potent inhibitor,showing remarkable efficacy against WT HIV-1(50%effective concentration(EC_(50))=2 nmol/L)and five mutant strains(EC_(50)=0.003-0.073μmol/L),which was significantly superior to that of compound 5.This optimized derivative demonstrated substantially improved pharmacological properties compared to existing drugs etravirine(ETR)and rilpivirine(RPV),showing a 4-fold reduction in cytotoxicity alongside 6-fold enhancement in selectivity index(50%cytotoxic concentration(CC_(50))=19.69μmol/L,selectivity index(SI)=7438).The compound's metabolic profile revealed exceptional stability,with an elimination half-life(t_(1/2)=41.4 min)more than double that of RPV(t_(1/2)=16.03min).Comprehensive safety evaluation indicated minimal cytochrome P450(CYP)enzymes interference,low cardiac ion channel activity,and no observable acute toxicity,collectively suggesting a reduced risk profile for therapeutic applications.These promising characteristics significantly advance the development potential of biphenyl-piperidine-triazine derivatives as next-generation non-nucleoside reverse transcriptase inhibitors(NNRTIs),offering enhanced efficacy,improved safety,and favorable pharmacokinetic properties for antiretroviral therapy.展开更多
Reforestation initiatives are often limited by insufficient seeds,a problem exacerbated by natural variability in tree flowering and seed production and climate change and other environmental challenges.Innovative and...Reforestation initiatives are often limited by insufficient seeds,a problem exacerbated by natural variability in tree flowering and seed production and climate change and other environmental challenges.Innovative and adaptive solutions such as in vitro propagation are thus needed.Tissue culture can provide high-quality propagation material for tree conservation and mass propagation,but faces technical,economic,regulatory,and social barriers.Obstacles related to the academia-industry interface and to stakeholder concerns are discussed and actions suggested to overcome these barriers to realize the full potential of tree micropropagation.These include refining techniques to improve efficiency and reduce costs;establishing collaborations among researchers,industry,and foresters;and reducing points of contention and misinformation regarding genetic diversity and public perception.International collaborative initiatives,exemplified by the EU COST Action CA21157 COPYTREE,are elementary for achieving these goals.展开更多
文摘A repeated sequence DNA fragment, L5B-4, was cloned from the 5 kb BamHI DNA fragments of rat genomic DNA. The expressions of the L5B-4 DNA fragment are different in liver and hepatoma cells. The amounts of transcripts in hepatoma cells are lower in nucleus and higher in cytoplasm, especially in polysomal RNA, as compared with that in liver cells. The alteration shown in polysomal RNA of hepatoma cells seems to be specific. These results are discussed with respect to the possible function of this repeated DNA and its variation in hepatoma cells.
基金financially supported by the National Natural Science Foundation of China(U1663225)the Changjiang Scholar Program of Chinese Ministry of Education(IRT15R52)the program of Introducing Talents of Discipline to Universities-Plan 111(B20002)of Ministry of Science and Technology and the Ministry of Education of China and the project “Depollut Air”of Interreg V France-WallonieVlaanderen。
文摘Graphitic carbon nitride(g-C_(3)N_(4))has attracted great interest in photocatalysis and photoelectrocatalysis.However,their poor hydrophilicity poses a great challenge for their applications in aqueous environment.Here,we demonstrate synthesis of a hydrophilic bi-functional hierarchical architecture by the assembly of B-doped g-C_(3)N_(4)nanoplatelets.Such hierarchical B-doped g-C_(3)N_(4)material enables full utilization of their highly enhanced visible light absorption and photogenerated carrier separation in aqueous medium,leading to an excellent photocatalytic H_(2)O_(2)production rate of 4240.3μM g^(-1)h^(-1),2.84,2.64 and 2.13 times higher than that of the bulk g-C_(3)N_(4),g-C_(3)N_(4)nanoplatelets and bulk B doped g-C_(3)N_(4),respectively.Photoanodes based on these hierarchical architectures can generate an unprecedented photocurrent density of 1.72 m A cm^(-2)at 1.23 V under AM 1.5 G illumination for photoelectrochemical water splitting.This work makes a fundamental improvement towards large-scale exploitation of highly active,hydrophilic and stable metal-free g-C_(3)N_(4)photocatalysts for various practical applications.
文摘1 INTRODUCTIONThe determination of the solids hold-up and local solidfluxes is of paramount importance in the study ofthe hydrodynamics of a two-phase flow.Several tech-niques have been used during the past decades(Table1).These methods can be classified in two groups,depending on their possible disturbance of the two-
基金financially supported by the National Key R&D Program of China (2022YFB3504000)National Natural Science Foundation of China (22293022, 22402155, U22B6011)+4 种基金Program of Introducing Talents of Discipline to Universities-Plan 111 (B20002) from the Ministry of Science and Technology and the Ministry of Education of China,Natural Science Foundation of Hubei Province (2023AFB605, 2025AFB033)Dawning Program of Wuhan (2023020201020306)supported by the European Commission Interreg V France-Wallonie-Vlaanderen project“Depollut Air”,the Program Win2Wal (TCHARBONACTIF:2110120)Wallonia Region of Belgium,and the National Key R&D Program Intergovernmental Technological Innovation Special Cooperation Project Wallonia-Brussels/China (MOST)(SUB/2021/IND493971/524448)Hubei Provincial Department of Education for the “Chutian Scholar” program。
文摘Enhancing the light olefin selectivity and extending the catalytic durability remain critical challenges for ZSM-5 zeolites in the methanol to olefins(MTO)conversion,while the inherent diffusion restriction along the MFI b-axis direction and poor coke accommodation are the main limiting factors.In this work,we developed a hierarchically singlecrystalline ZSM-5 sheet architecture that features an interconnected multiscale porosity and a remarkably reduced baxis thickness(<50 nm),as quantitatively verified by threedimensional(3D)electron tomography.Real-time confocal laser scanning microscopy(CLSM)tracking demonstrated a significant enhancement in molecular diffusivity compared to conventional micron-sized ZSM-5 counterparts(Micro-ZSM5).This engineered structure allows abundant aluminum sites to be distributed on the highly accessible diffusion pathways,and displays an enlarged coke accommodation of 16.31 wt%with a coke deposition rate of 0.59 mg g^(-1) h^(-1),which was only one third of that in the Micro-ZSM-5.In a continuous MTO process,this novel hierarchical ZSM-5 sheet(Hier-ZSM-5-S)kept an average selectivity to ethylene and propene of 63.5%on stream for 22.2 h(WHSV=3.6 h−1,T=480℃),which was 19%higher and 6.5 times longer than those of Micro-ZSM-5,respectively.This hierarchically shortened b-axis structure establishes a generalizable paradigm for enhanced diffusion and coke accommodation in a precisely designed pore system,which is expected to be adjusted and applied for varying reactions.
基金partially funded by the European Commission HORIZON 2020 Framework Programme under grant agreement No 755269
文摘A high-Mn austenitic steel Fe-14Cr-12Ni-10Mn-3Cu-2.5Al-1Nb was tested at 500℃in static Pb-Bi eutectic for 10000 h.In the course of the test,oxygen concentration in liquid metal was cycled from~10^(-6) to~10^(-9) mass%,which provides oxidation and dissolution regimes,respectively.After 10000 h exposure steel showed formation of ferrite corrosion zone depleted in Mn,Ni,Cu,Cr,Fe and penetrated by Pb and Bi.Average depth of corrosion is 15±5μm,while maximum corrosion depth locally reaches~35μm.Dissolved Mn and Cr re-precipitated in the vicinity of steel surface in a form of stratified Mn-O/Cr-Mn-O oxide scale.Obtained results were compared to those of similar Al-alloyed austenitic steels with lower Mn content,which exhibited protective oxidation under same test conditions.The phenomenological mechanism of oxygen-driven de-alloying of steel in Pb-Bi[O]is discussed.
基金supported by the Natural Science Foundation of Jiangsu Province(No.BK20220409)the National Natural Science Foundation of China(No.22401153)+2 种基金the FWO[Fund for Scientific Research-Flanders(Belgium)]for financial support(recipient Erik V.Van der Eycken)the Research Council of the KU Leuven(recipient Erik V.Van der Eycken)the support of the"RUDN University Strategic Academic Leadership Program"(recipient Erik V.Van der Eycken).
文摘Peptides play important roles in chemistry,medicinal chemistry and life science,due to their high efficiency and specificity,unusual biological and therapeutic properties.As naturally occurring peptides often face with their intrinsic limitations including metabolic instability and low membrane permeability,the strategies for synthesizing unnatural amino acids and peptides are explored.Among the methods for modifying amino acids and peptides,chemo-and site-selective approaches are preferred because of the ability to fine-tuning structural features.Recently,transition metal-catalyzed Csingle bondH activation has been employed for the functionalization of amino acids and peptides.Through domino Csingle bondH activation/annulation,a series of structurally complex and diverse amino acids and peptides is constructed.This review highlights recent advances in the synthesis of unnatural amino acids and peptides via transition metal-catalyzed Csingle bondH activation/annulation.
基金financially supported by National Natural Science Foundation of China(No.82304297)the State Key Laboratory of Natural and Biomimetic Drugs(No.K202408)。
文摘To enhance the anti-resistance efficacy of our previously disclosed naphthyl-triazine 5,structure-based drug design strategy was rationally conducted to design a series of novel biphenyl-piperidine-triazinecontaining non-nucleoside reverse transcriptase inhibitors.Remarkably,several of these compounds demonstrated single-digit nanomolar antiviral potency against both wild-type(WT)human immunodeficiency virus-1(HIV-1)and five clinically relevant mutant strains.Among these,compound 11s emerged as the most potent inhibitor,showing remarkable efficacy against WT HIV-1(50%effective concentration(EC_(50))=2 nmol/L)and five mutant strains(EC_(50)=0.003-0.073μmol/L),which was significantly superior to that of compound 5.This optimized derivative demonstrated substantially improved pharmacological properties compared to existing drugs etravirine(ETR)and rilpivirine(RPV),showing a 4-fold reduction in cytotoxicity alongside 6-fold enhancement in selectivity index(50%cytotoxic concentration(CC_(50))=19.69μmol/L,selectivity index(SI)=7438).The compound's metabolic profile revealed exceptional stability,with an elimination half-life(t_(1/2)=41.4 min)more than double that of RPV(t_(1/2)=16.03min).Comprehensive safety evaluation indicated minimal cytochrome P450(CYP)enzymes interference,low cardiac ion channel activity,and no observable acute toxicity,collectively suggesting a reduced risk profile for therapeutic applications.These promising characteristics significantly advance the development potential of biphenyl-piperidine-triazine derivatives as next-generation non-nucleoside reverse transcriptase inhibitors(NNRTIs),offering enhanced efficacy,improved safety,and favorable pharmacokinetic properties for antiretroviral therapy.
基金funded by COST Action CA21157“European Network for Innovative Woody Plant Cloning”www.cost.eusupported by COST(European Cooperation in Science and Technology)www.cost.eu。
文摘Reforestation initiatives are often limited by insufficient seeds,a problem exacerbated by natural variability in tree flowering and seed production and climate change and other environmental challenges.Innovative and adaptive solutions such as in vitro propagation are thus needed.Tissue culture can provide high-quality propagation material for tree conservation and mass propagation,but faces technical,economic,regulatory,and social barriers.Obstacles related to the academia-industry interface and to stakeholder concerns are discussed and actions suggested to overcome these barriers to realize the full potential of tree micropropagation.These include refining techniques to improve efficiency and reduce costs;establishing collaborations among researchers,industry,and foresters;and reducing points of contention and misinformation regarding genetic diversity and public perception.International collaborative initiatives,exemplified by the EU COST Action CA21157 COPYTREE,are elementary for achieving these goals.
