With the increasing severity of arsenic(As)pollution,quantifying the environmental behavior of pollutant based on numerical model has become an important approach to determine the potential impacts and finalize the pr...With the increasing severity of arsenic(As)pollution,quantifying the environmental behavior of pollutant based on numerical model has become an important approach to determine the potential impacts and finalize the precise control strategies.Taking the industrialintensive Jinsha River Basin as typical area,a two-dimensional hydrodynamic water quality model coupled with Soil andWater Assessment Tool(SWAT)model was developed to accurately simulate the watershed-scale distribution and transport of As in the terrestrial and aquatic environment at high spatial and temporal resolution.The effects of hydro-climate change,hydropower station construction and non-point source emissions on Aswere quantified based on the coupled model.The result indicated that higher As concentration areas mainly centralized in urban districts and concentration slowly decreased from upstream to downstream.Due to the enhanced rainfall,the As concentration was significantly higher during the rainy season than the dry season.Hydro-climate change and the construction of hydropower station not only affected the dissolved As concentration,but also affected the adsorption and desorption of As in sediment.Furthermore,As concentration increased with the input of non-point source pollution,with the maximum increase about 30%,resulting that non-point sources contributed important pollutant impacts to waterways.The coupled model used in pollutant behavior analysis is generalwith high potential application to predict and mitigate water pollution.展开更多
The integration of industry and education can not only give full play to the leading role of talents in rural revitalization,promote the development of social resources such as science and technology,industry,culture,...The integration of industry and education can not only give full play to the leading role of talents in rural revitalization,promote the development of social resources such as science and technology,industry,culture,education,and medical care,but also provide strong momentum for the rural revitalization strategy,and comprehensively promote rural construction in the new era.This paper analyzes the significance and problems of cultivating talents for rural revitalization through the integration of industry and education in higher vocational education,and makes a preliminary exploration on the countermeasures from three aspects:strengthening top-level design to connect education with rural areas,establishing a diversified training mechanism to meet talent needs,and innovating cooperation models to shorten the distance between schools and villages.展开更多
Pancreatic ductal adenocarcinoma(PDAC)is an aggressive malignancy with a poor prognosis that is driven primarily by oncogenic KRAS mutations present in>90%of cases.KRAS mutations,particularly the G12D mutation whic...Pancreatic ductal adenocarcinoma(PDAC)is an aggressive malignancy with a poor prognosis that is driven primarily by oncogenic KRAS mutations present in>90%of cases.KRAS mutations,particularly the G12D mutation which dominates in PDAC,fuel tumor initiation,progression,and immune evasion,thereby contributing to therapy resistance.Nevertheless,KRAS has long been considered“undruggable”due to its structure.Recent advances have spurred transformative progress in direct KRAS inhibition.While FDAapproved mutation-specific and pan-KRAS inhibitors show limited efficacy in PDAC,emerging agents(MRTX1133 and RMC-9805)have demonstrated preclinical promise.However,resistance remains a critical hurdle and is driven by pathway reactivation,secondary mutations,and metabolic adaptations.Alternative strategies targeting upstream regulators(SHP2 and SOS1)aim to block KRAS activation and associated resistance mechanisms.Preclinical studies have also highlighted synergistic benefits of combining KRAS inhibitors with MEK,PI3K,or CDK4/6 inhibitors,which are now undergoing clinical evaluation.Immunotherapies,including KRAS-targeted vaccines and adoptive T-cell therapies,have further expanded the therapeutic landscape of enhancing KRAS-targeted therapies in PDAC.The molecular basis of KRAS-driven PDAC,current inhibitors,resistance mechanisms,and innovative strategies are discussed herein to address treatment barriers.Opportunities to improve clinical outcomes are underscored in this challenging malignancy by integrating insights from preclinical and clinical research.展开更多
Photodynamic therapy(PDT)is a promising cancer treatment.This study investigated the antitumor effects and mechanisms of a novel photosensitizer meso-5-[ρ-diethylene triamine pentaacetic acid-aminophenyl]−10,15,20-tr...Photodynamic therapy(PDT)is a promising cancer treatment.This study investigated the antitumor effects and mechanisms of a novel photosensitizer meso-5-[ρ-diethylene triamine pentaacetic acid-aminophenyl]−10,15,20-triphenyl-porphyrin(DTP)mediated PDT(DTP-PDT).Cell viability,reactive oxygen species(ROS),and apoptosis were measured with a Cell Counting Kit-8 assay,DCFH-DA fluorescent probe,and Hoechst staining,respectively.Cell apoptosis-and autophagy-related proteins were examined using western blotting.RNA sequencing was used to screen differentially expressed mRNAs(DERs),and bioinformatic analysis was performed to identify the major biological events after DTP-PDT.Our results show that DTP-PDT inhibited cell growth and induced ROS generation in MCF-7 and SGC7901 cells.The ROS scavenger N-acetyl-L-cysteine(NAC)and the P38 MAPK inhibitor SB203580 alleviated DTP-PDT-induced cytotoxicity.DTP-PDT induced cell apoptosis together with upregulated Bax and downregulated Bcl-2,which could also be inhibited by NAC or SB203580.The level of LC3B-Ⅱ,a marker of autophagy,was increased by DTP-PDT.A total of 3496 DERs were obtained after DTP-PDT.Gene Ontology and Kyoto Encyclopedia of Genes and Genomes analyses indicated that DERs included those involved in cytosolic ribosomes,the nuclear lumen,protein binding,cell cycle,protein targeting to the endoplasmic reticulum,and ribosomal DNA replication.Disease Ontology and Reactome enrichment analyses indicated that DERs were associated with a variety of cancers and cell cycle checkpoints.Protein-protein interaction results demonstrated that cdk1 and rps27a ranked in the top 10 interacting genes.Therefore,DTP-PDT could inhibit cell growth and induce cell apoptosis and autophagy,partly through ROS and the P38 MAPK signaling pathway.Genes associated with the cell cycle,ribosomes,DNA replication,and protein binding may be the key changes in DTP-PDT-mediated cytotoxicity.展开更多
We generalize the formalism proposed by Dalibard, Dupont-Roc, and Cohen-Tannoudji(the DDC formalism) in the fourth order for two atoms in interaction with scalar fields in vacuum to a thermal bath at finite temperatur...We generalize the formalism proposed by Dalibard, Dupont-Roc, and Cohen-Tannoudji(the DDC formalism) in the fourth order for two atoms in interaction with scalar fields in vacuum to a thermal bath at finite temperature T, and then calculate the interatomic interaction energy of two ground-state atoms separately in terms of the contributions of thermal fluctuations and the radiation reaction of the atoms and analyze in detail the thermal corrections to the van der Waals and Casimir–Polder interactions. We discover a particular region, i.e. 4(λ3β)(1/2) ■ L■λwith L, β and λ denoting the interatomic separation, the wavelength of thermal photons and the transition wavelength of the atoms respectively, where the thermal corrections remarkably render the van der Waals force, which is usually attractive, repulsive, leading to an interesting crossover phenomenon of the interatomic interaction from attractive to repulsive as the temperature increases. We also find that the thermal corrections cause significant changes to the Casimir–Polder force when the temperature is sufficiently high, resulting in an attractive force proportional to TL-3in the λ ■ β ■ L region, and a force that can be either attractive or repulsive and even vanishing in the β ■ λ ■ L region depending on the interatomic separation.展开更多
We study the interaction potential of two nonidentical ground-state atoms coupled to a scalar field in a vacuum by separately calculating the contributions of vacuum fluctuations and those of the radiation reaction of...We study the interaction potential of two nonidentical ground-state atoms coupled to a scalar field in a vacuum by separately calculating the contributions of vacuum fluctuations and those of the radiation reaction of the atoms.Both cases of atoms in a free space and in parallel or vertical alignment to a reflecting boundary are considered.For the former case,we find that the leading-order interaction potential in the regionλA?L?λB exhibits the same separationdependence as that in the region L?λA?λB,where L,λA andλB are respectively the interatomic separation and the transition wavelengths of two atoms withλA?λB.For the latter case,we find that boundary-induced modifications are very remarkable when L?z,with z characterizing the separation between the two-atom system and the boundary.Particularly,when L further satisfies L?λA and L?λB,the interaction potential in the parallel-and the verticalalignment cases respectively scales as z4L-7 and z2L-5,the L-dependence of which is one order higher than those of two atoms in regions where L?z and meanwhile L?λA or/and L?λB.Our results suggest that retardation for the interaction potential of two nonidentical atoms with remarkably distinctive transition frequencies happens only when the interatomic separation is much greater than the transition wavelengths of both atoms.展开更多
Single atom catalysts(SACs)have become a hot topic in catalysis research due to their 100%atomic utilization,unique coordination environment,and superior catalytic performance.To explain the special catalytic behavior...Single atom catalysts(SACs)have become a hot topic in catalysis research due to their 100%atomic utilization,unique coordination environment,and superior catalytic performance.To explain the special catalytic behavior of SACs and maximize the advantages of single atom configurations,understanding the structure–performance relationship of SACs at the atomic level is key to the research.X-ray absorption fine structure(XAFS)provides an irreplaceable method for characterizing SACs,which can be applied to almost all transition-metal SACs and can obtain rich structural information about atomistic structures and electronic properties.In this review,starting from the basic principles of XAFS technology,we discuss the application of extended X-ray absorption fine structure(EXAFS)and X-ray absorption near edge structure(XANES)spectroscopy in the study of the local coordination,symmetry,hybrid of orbitals,oxidation state,charge transfer and many other structural and electronic properties.After that,we introduce the emerging advanced X-ray spectroscopy methods that improve characterization capabilities and compensate for the shortcomings of traditional XAFS methods in SAC research,and then discuss in-situ and operando experimental techniques for SAC characterization to monitor the dynamic structure of the active sites in the presence of reactants under reaction conditions.展开更多
Surface modification of metallic nanocatalysts with organic ligands has emerged as an effective strategy to enhance catalytic selectivity,although offten at the expense of catalytic activity.In this study,we demonstra...Surface modification of metallic nanocatalysts with organic ligands has emerged as an effective strategy to enhance catalytic selectivity,although offten at the expense of catalytic activity.In this study,we demonstrate a compelling approach by surface modifying Pd2S nanocrystals with PPhz ligands,resulting in a catalyst with excellent catalytic activity and durable selectivity for the semi-hydrogenation of terminal alkynes.Experimental and theoretical investigations reveal that the presence of S sites on the Pd surface directs PPh_(3) ligands to preferentially form covalent bonds with S,creating distinctive surface S=PPh_(3) motifs.This configuration induces a partial positive charge on Pd,facilitating hydrogen transfer and thus promoting catalytic activity.Furthermore,the covalent bond between the ligand and catalyst surface forms a robust network,ensuring ligand stability and increasing the hydrogenation energy barrier of olefins.Consequently,the Pd_(4)S@PPhz catalyst exhibits an improved catalytic selectivity with durability in terminal alkyne semi-hydrogenation.This study introduces an effective strategy for designing selective hydrogenation catalysts with an enhanced performance.展开更多
What is already known about this topic?Hepatitis A(HA)is caused by acute hepatitis A virus(HAV)infection and was once very common in China.Following the 2008 introduction of the HA vaccine into the national Expanded P...What is already known about this topic?Hepatitis A(HA)is caused by acute hepatitis A virus(HAV)infection and was once very common in China.Following the 2008 introduction of the HA vaccine into the national Expanded Program on Immunization(EPI),the incidence of reported HA in China decreased markedly.However,HA epidemics still occur in Liaoning Province every 3–5 years,although with far fewer cases than in the pre-HA-vaccination era.What is added by this report?Between January 1,2020 and March 18,2020,the number of reported cases of HA in Dalian and Dandong cities of Liaoning Province increased significantly compared with the same period in previous years.All cases were sporadic,and cases were seen in nearly every township.The increase in HA occurred one month after local fresh seafood became available with most cases being among adults.A casecontrol study showed that consuming raw or undercooked seafood,clams,snapping shrimp,and oysters were significantly associated with the increase in HA.What are the implications for public health practices?Strengthening health education for residents to avoid consumption of raw seafood and encouraging HAV vaccination of adults aged 20 to 54 years are important to prevent periodic HAV endemic outbreaks.Further multisectoral cooperation must be emphasized on HA surveillance in areas with a high prevalence of HA.展开更多
Supported metal catalysts integrating advantages of catalytic hydrogenation and stoichiometric reduction are highly desirable for the green production of fine chemicals.Decoupling catalytic hydrogenation into H_(2)act...Supported metal catalysts integrating advantages of catalytic hydrogenation and stoichiometric reduction are highly desirable for the green production of fine chemicals.Decoupling catalytic hydrogenation into H_(2)activation and selective reduction taking place at different locations is expected to provide an effective strategy to fabricate such catalyst systems.Herein,we report a decoupled hydrogenation system by modifying Pt catalysts supported on reducible In2O3 with ethylenediamine(EDA).The system exhibits good catalytic performance in oximes production from nitroalkanes,an industrially important reaction,by employing H_(2).Systematic studies demonstrate that the surface coordination of EDA on Pt is crucial to passivate the Pt surface from nitro hydrogenation without inhibiting H_(2)activation.The activated H_(2)species can then transfer and reduce the In_(2)O_(3)support in situ to generate sustainable stoichiometric reducing agents for the chemoselective reduction of nitroalkanes.Based upon the mechanistic understanding,a sustainable strategy for the production of oximes has been successfully fabricated.展开更多
While the enzymatic reduction of unsaturated compounds usually has high specificity,highly selective reduction processes are hardly realized by heterogeneous industrial catalysts,which is critical for the green produc...While the enzymatic reduction of unsaturated compounds usually has high specificity,highly selective reduction processes are hardly realized by heterogeneous industrial catalysts,which is critical for the green production of many fine chemicals.Here,we report an unexpected discovery of a biomimetic behavior of dicyandiamide(DICY)-modified Pt nanocatalysts for the green hydrogenation of a wide range of nitroaromatics.We demonstrate that the surface modification by DICY not only prevents the direct contact of nitroaromatic reactants with Pt surface but also induces an effective non-contact hydrogenation mechanism mediated by protons and electrons.In such a process,the DICY layer serves as a“semi-permeable membrane”to allow the permeation of H_(2) molecules for being activated into electrons and protons at the Pt-DICY interface.With the generation of separated protons and electrons,the nitro group with strong electrophilic properties can be hydrogenated through the electron transfer followed by the proton transfer,which is facilitated by the hydrogen bonding network formed by protonated DICY.The unique mechanism makes it highly directional toward the hydrogenation of nitro groups without side reactions.Owing to its capability to largely eliminate the waste generation,the developed Pt-DICY catalysts have been successfully applied for the green industrial production of many important aniline intermediates.展开更多
基金supported by the National Key Research and Development Program of China(No.2017YFC1502504)the National Natural Science Foundation of China(No.41877531).
文摘With the increasing severity of arsenic(As)pollution,quantifying the environmental behavior of pollutant based on numerical model has become an important approach to determine the potential impacts and finalize the precise control strategies.Taking the industrialintensive Jinsha River Basin as typical area,a two-dimensional hydrodynamic water quality model coupled with Soil andWater Assessment Tool(SWAT)model was developed to accurately simulate the watershed-scale distribution and transport of As in the terrestrial and aquatic environment at high spatial and temporal resolution.The effects of hydro-climate change,hydropower station construction and non-point source emissions on Aswere quantified based on the coupled model.The result indicated that higher As concentration areas mainly centralized in urban districts and concentration slowly decreased from upstream to downstream.Due to the enhanced rainfall,the As concentration was significantly higher during the rainy season than the dry season.Hydro-climate change and the construction of hydropower station not only affected the dissolved As concentration,but also affected the adsorption and desorption of As in sediment.Furthermore,As concentration increased with the input of non-point source pollution,with the maximum increase about 30%,resulting that non-point sources contributed important pollutant impacts to waterways.The coupled model used in pollutant behavior analysis is generalwith high potential application to predict and mitigate water pollution.
基金2023 Excellent Youth Project of Scientific Research,Hunan Provincial Department of Education:Research and Practice on Cultivating Talents for Rural Revitalization through Industry-Education Integration in Higher Vocational Colleges(Project No.:23B1076)。
文摘The integration of industry and education can not only give full play to the leading role of talents in rural revitalization,promote the development of social resources such as science and technology,industry,culture,education,and medical care,but also provide strong momentum for the rural revitalization strategy,and comprehensively promote rural construction in the new era.This paper analyzes the significance and problems of cultivating talents for rural revitalization through the integration of industry and education in higher vocational education,and makes a preliminary exploration on the countermeasures from three aspects:strengthening top-level design to connect education with rural areas,establishing a diversified training mechanism to meet talent needs,and innovating cooperation models to shorten the distance between schools and villages.
基金supported by the Tianshan Talents-Youth Science and Technology Innovation Talents Training Program of Xinjiang Autonomous Region(Grant No.2022TSYCCX0035)the Xinjiang Key Laboratory of Natural Medicines Active Components and Drug Release Technology(Grant No.XJDX1713)+2 种基金the“Fourteenth Five-Year Plan”Key Discipline Construction Project of Xinjiang Autonomous Region(2021)the Engineering Research Center of Xinjiang and Central Asian Medicine Resources,Ministry of Education(2023)the Xinjiang Key Laboratory of Biopharmaceuticals and Medical Devices(2023)。
文摘Pancreatic ductal adenocarcinoma(PDAC)is an aggressive malignancy with a poor prognosis that is driven primarily by oncogenic KRAS mutations present in>90%of cases.KRAS mutations,particularly the G12D mutation which dominates in PDAC,fuel tumor initiation,progression,and immune evasion,thereby contributing to therapy resistance.Nevertheless,KRAS has long been considered“undruggable”due to its structure.Recent advances have spurred transformative progress in direct KRAS inhibition.While FDAapproved mutation-specific and pan-KRAS inhibitors show limited efficacy in PDAC,emerging agents(MRTX1133 and RMC-9805)have demonstrated preclinical promise.However,resistance remains a critical hurdle and is driven by pathway reactivation,secondary mutations,and metabolic adaptations.Alternative strategies targeting upstream regulators(SHP2 and SOS1)aim to block KRAS activation and associated resistance mechanisms.Preclinical studies have also highlighted synergistic benefits of combining KRAS inhibitors with MEK,PI3K,or CDK4/6 inhibitors,which are now undergoing clinical evaluation.Immunotherapies,including KRAS-targeted vaccines and adoptive T-cell therapies,have further expanded the therapeutic landscape of enhancing KRAS-targeted therapies in PDAC.The molecular basis of KRAS-driven PDAC,current inhibitors,resistance mechanisms,and innovative strategies are discussed herein to address treatment barriers.Opportunities to improve clinical outcomes are underscored in this challenging malignancy by integrating insights from preclinical and clinical research.
基金supported by the Applied Basic Research Project of Shanxi Province(201901D211470)Scientific and Technological Innovation Programs of Higher Education Institutions in Shanxi Province(201802093)The National Natural Science Foundation of China(No.81773765).
文摘Photodynamic therapy(PDT)is a promising cancer treatment.This study investigated the antitumor effects and mechanisms of a novel photosensitizer meso-5-[ρ-diethylene triamine pentaacetic acid-aminophenyl]−10,15,20-triphenyl-porphyrin(DTP)mediated PDT(DTP-PDT).Cell viability,reactive oxygen species(ROS),and apoptosis were measured with a Cell Counting Kit-8 assay,DCFH-DA fluorescent probe,and Hoechst staining,respectively.Cell apoptosis-and autophagy-related proteins were examined using western blotting.RNA sequencing was used to screen differentially expressed mRNAs(DERs),and bioinformatic analysis was performed to identify the major biological events after DTP-PDT.Our results show that DTP-PDT inhibited cell growth and induced ROS generation in MCF-7 and SGC7901 cells.The ROS scavenger N-acetyl-L-cysteine(NAC)and the P38 MAPK inhibitor SB203580 alleviated DTP-PDT-induced cytotoxicity.DTP-PDT induced cell apoptosis together with upregulated Bax and downregulated Bcl-2,which could also be inhibited by NAC or SB203580.The level of LC3B-Ⅱ,a marker of autophagy,was increased by DTP-PDT.A total of 3496 DERs were obtained after DTP-PDT.Gene Ontology and Kyoto Encyclopedia of Genes and Genomes analyses indicated that DERs included those involved in cytosolic ribosomes,the nuclear lumen,protein binding,cell cycle,protein targeting to the endoplasmic reticulum,and ribosomal DNA replication.Disease Ontology and Reactome enrichment analyses indicated that DERs were associated with a variety of cancers and cell cycle checkpoints.Protein-protein interaction results demonstrated that cdk1 and rps27a ranked in the top 10 interacting genes.Therefore,DTP-PDT could inhibit cell growth and induce cell apoptosis and autophagy,partly through ROS and the P38 MAPK signaling pathway.Genes associated with the cell cycle,ribosomes,DNA replication,and protein binding may be the key changes in DTP-PDT-mediated cytotoxicity.
基金the NSFC under Grants No.11690034,No.12075084,No.11875172 and No.12047551,and No.12105061the K C Wong Magna Fund in Ningbo University
文摘We generalize the formalism proposed by Dalibard, Dupont-Roc, and Cohen-Tannoudji(the DDC formalism) in the fourth order for two atoms in interaction with scalar fields in vacuum to a thermal bath at finite temperature T, and then calculate the interatomic interaction energy of two ground-state atoms separately in terms of the contributions of thermal fluctuations and the radiation reaction of the atoms and analyze in detail the thermal corrections to the van der Waals and Casimir–Polder interactions. We discover a particular region, i.e. 4(λ3β)(1/2) ■ L■λwith L, β and λ denoting the interatomic separation, the wavelength of thermal photons and the transition wavelength of the atoms respectively, where the thermal corrections remarkably render the van der Waals force, which is usually attractive, repulsive, leading to an interesting crossover phenomenon of the interatomic interaction from attractive to repulsive as the temperature increases. We also find that the thermal corrections cause significant changes to the Casimir–Polder force when the temperature is sufficiently high, resulting in an attractive force proportional to TL-3in the λ ■ β ■ L region, and a force that can be either attractive or repulsive and even vanishing in the β ■ λ ■ L region depending on the interatomic separation.
基金supported in part by the NSFC under Grant Nos.11690034,12075084,11875172,12047551 and 12105061the KC Wong Magna Fund in Ningbo University。
文摘We study the interaction potential of two nonidentical ground-state atoms coupled to a scalar field in a vacuum by separately calculating the contributions of vacuum fluctuations and those of the radiation reaction of the atoms.Both cases of atoms in a free space and in parallel or vertical alignment to a reflecting boundary are considered.For the former case,we find that the leading-order interaction potential in the regionλA?L?λB exhibits the same separationdependence as that in the region L?λA?λB,where L,λA andλB are respectively the interatomic separation and the transition wavelengths of two atoms withλA?λB.For the latter case,we find that boundary-induced modifications are very remarkable when L?z,with z characterizing the separation between the two-atom system and the boundary.Particularly,when L further satisfies L?λA and L?λB,the interaction potential in the parallel-and the verticalalignment cases respectively scales as z4L-7 and z2L-5,the L-dependence of which is one order higher than those of two atoms in regions where L?z and meanwhile L?λA or/and L?λB.Our results suggest that retardation for the interaction potential of two nonidentical atoms with remarkably distinctive transition frequencies happens only when the interatomic separation is much greater than the transition wavelengths of both atoms.
基金supported by the National Natural Science Foundation of China(22178302)。
文摘Single atom catalysts(SACs)have become a hot topic in catalysis research due to their 100%atomic utilization,unique coordination environment,and superior catalytic performance.To explain the special catalytic behavior of SACs and maximize the advantages of single atom configurations,understanding the structure–performance relationship of SACs at the atomic level is key to the research.X-ray absorption fine structure(XAFS)provides an irreplaceable method for characterizing SACs,which can be applied to almost all transition-metal SACs and can obtain rich structural information about atomistic structures and electronic properties.In this review,starting from the basic principles of XAFS technology,we discuss the application of extended X-ray absorption fine structure(EXAFS)and X-ray absorption near edge structure(XANES)spectroscopy in the study of the local coordination,symmetry,hybrid of orbitals,oxidation state,charge transfer and many other structural and electronic properties.After that,we introduce the emerging advanced X-ray spectroscopy methods that improve characterization capabilities and compensate for the shortcomings of traditional XAFS methods in SAC research,and then discuss in-situ and operando experimental techniques for SAC characterization to monitor the dynamic structure of the active sites in the presence of reactants under reaction conditions.
基金National Natural Science Foundation of China(grant no.92261207,and NSFC Center for Single-Atom Catalysis under grant no.22388102)New Cornerstone Science Foundation.R.Q.acknowledges support from National Key R&D Program of China(2022YFA1504500)+2 种基金Young Scientists Fund of the National Natural Science Foundation of China(22202164)Natural Science Foundation of Fujian Province(2023J05006)Fundamental Research Funds for the Central Universities(20720230002).
文摘Surface modification of metallic nanocatalysts with organic ligands has emerged as an effective strategy to enhance catalytic selectivity,although offten at the expense of catalytic activity.In this study,we demonstrate a compelling approach by surface modifying Pd2S nanocrystals with PPhz ligands,resulting in a catalyst with excellent catalytic activity and durable selectivity for the semi-hydrogenation of terminal alkynes.Experimental and theoretical investigations reveal that the presence of S sites on the Pd surface directs PPh_(3) ligands to preferentially form covalent bonds with S,creating distinctive surface S=PPh_(3) motifs.This configuration induces a partial positive charge on Pd,facilitating hydrogen transfer and thus promoting catalytic activity.Furthermore,the covalent bond between the ligand and catalyst surface forms a robust network,ensuring ligand stability and increasing the hydrogenation energy barrier of olefins.Consequently,the Pd_(4)S@PPhz catalyst exhibits an improved catalytic selectivity with durability in terminal alkyne semi-hydrogenation.This study introduces an effective strategy for designing selective hydrogenation catalysts with an enhanced performance.
文摘What is already known about this topic?Hepatitis A(HA)is caused by acute hepatitis A virus(HAV)infection and was once very common in China.Following the 2008 introduction of the HA vaccine into the national Expanded Program on Immunization(EPI),the incidence of reported HA in China decreased markedly.However,HA epidemics still occur in Liaoning Province every 3–5 years,although with far fewer cases than in the pre-HA-vaccination era.What is added by this report?Between January 1,2020 and March 18,2020,the number of reported cases of HA in Dalian and Dandong cities of Liaoning Province increased significantly compared with the same period in previous years.All cases were sporadic,and cases were seen in nearly every township.The increase in HA occurred one month after local fresh seafood became available with most cases being among adults.A casecontrol study showed that consuming raw or undercooked seafood,clams,snapping shrimp,and oysters were significantly associated with the increase in HA.What are the implications for public health practices?Strengthening health education for residents to avoid consumption of raw seafood and encouraging HAV vaccination of adults aged 20 to 54 years are important to prevent periodic HAV endemic outbreaks.Further multisectoral cooperation must be emphasized on HA surveillance in areas with a high prevalence of HA.
基金supported by the National Key R&D Program of China(grant no.2017YFA0207302)the National Natural Science Foundation of China(grant nos.21890752,21731005,21721001).
文摘Supported metal catalysts integrating advantages of catalytic hydrogenation and stoichiometric reduction are highly desirable for the green production of fine chemicals.Decoupling catalytic hydrogenation into H_(2)activation and selective reduction taking place at different locations is expected to provide an effective strategy to fabricate such catalyst systems.Herein,we report a decoupled hydrogenation system by modifying Pt catalysts supported on reducible In2O3 with ethylenediamine(EDA).The system exhibits good catalytic performance in oximes production from nitroalkanes,an industrially important reaction,by employing H_(2).Systematic studies demonstrate that the surface coordination of EDA on Pt is crucial to passivate the Pt surface from nitro hydrogenation without inhibiting H_(2)activation.The activated H_(2)species can then transfer and reduce the In_(2)O_(3)support in situ to generate sustainable stoichiometric reducing agents for the chemoselective reduction of nitroalkanes.Based upon the mechanistic understanding,a sustainable strategy for the production of oximes has been successfully fabricated.
基金supported by the National Key Research and Development Program of China(2017YFA0207302)the National Nature Science Foundation of China(21890752,21731005,22072116,92045303)+1 种基金support from the Tencent Foundation through the XPLORER PRIZEthe XAFS Station(BL14W1)of the Shanghai Synchrotron Radiation Facility(SSRF)。
文摘While the enzymatic reduction of unsaturated compounds usually has high specificity,highly selective reduction processes are hardly realized by heterogeneous industrial catalysts,which is critical for the green production of many fine chemicals.Here,we report an unexpected discovery of a biomimetic behavior of dicyandiamide(DICY)-modified Pt nanocatalysts for the green hydrogenation of a wide range of nitroaromatics.We demonstrate that the surface modification by DICY not only prevents the direct contact of nitroaromatic reactants with Pt surface but also induces an effective non-contact hydrogenation mechanism mediated by protons and electrons.In such a process,the DICY layer serves as a“semi-permeable membrane”to allow the permeation of H_(2) molecules for being activated into electrons and protons at the Pt-DICY interface.With the generation of separated protons and electrons,the nitro group with strong electrophilic properties can be hydrogenated through the electron transfer followed by the proton transfer,which is facilitated by the hydrogen bonding network formed by protonated DICY.The unique mechanism makes it highly directional toward the hydrogenation of nitro groups without side reactions.Owing to its capability to largely eliminate the waste generation,the developed Pt-DICY catalysts have been successfully applied for the green industrial production of many important aniline intermediates.
