Creating strongly coupled heterostructures with favorable catalytic activities is crucial for promoting the performance of catalytic reactions,especially those involve multiple intermediates.Herein,we fabricated a str...Creating strongly coupled heterostructures with favorable catalytic activities is crucial for promoting the performance of catalytic reactions,especially those involve multiple intermediates.Herein,we fabricated a strongly coupled platinum/molybdenum nitrides nanocluster heterostructure on nitrogen-doped reduced graphene oxide(Pt/Mo_(2)N-NrGO)for alkaline hydrogen evolution reaction.The well-defined Pt-containing Anderson-type polyoxometalates promote strong interfacial Pt-N-Mo bonding in Pt/Mo_(2)N-NrGO,which exhibits a remarkably low overpotential,high mass activity,and exceptional long-term durability(>500 h at 1500 mA cm^(-2))in an anion-exchange membrane water electrolyzer(AEMWE).Operando Raman spectroscopy and density functional theory reveal that pronounced electronic coupling at the Pt/Mo_(2)N cluster interface facilitates the catalytic decomposition of H_(2)O through synergistic stabilization of intermediates(Pt-H^(*)and Mo-OH^(*)),thereby enhancing the kinetics of the rate-determining Volmer step.Techno-economic analysis indicates a levelized hydrogen production cost of$2.02 kg^(-1),meeting the US DOE targets.Our strategy presents a viable pathway to designing next-generation catalysts for industrial AEMWE for green hydrogen production.展开更多
Gold nanoparticles(AuNPs)supported on the Cu-doped LaMnO_(3)perovskites exhibit strong Au-Mn-Cu synergy in the aerobic oxidation of gaseous ethanol to acetaldehyde(AC).The Au/LaMnCuO_(3)catalysts achieve AC yields exc...Gold nanoparticles(AuNPs)supported on the Cu-doped LaMnO_(3)perovskites exhibit strong Au-Mn-Cu synergy in the aerobic oxidation of gaseous ethanol to acetaldehyde(AC).The Au/LaMnCuO_(3)catalysts achieve AC yields exceeding 90%and a space-time yield of 715 g_(AC)g_(AU)^(-1)h^(-1)at 225℃,outperforming reported catalysts.The outstanding performance is attributed to adjacent Cu^(+)and Mn^(2+)ions in the perovskite surface,which,together with nearby AuNPs,contribute to the high activity and stability.The best-performing catalyst contains a Cu/Mn ratio of 1/3 in the perovskite.Doping too much Cu into the perovskite leads to metallic Cu,suppressing catalyst performance.Density functional theory(reaction energetics,electronic structure analysis)and microkinetics simulations aided in understanding the synergy between Cu and Mn and the role of AuNPs.The reaction involves two H abstraction steps:(1)O-H cleavage of adsorbed ethanol by the basic perovskite lattice oxygen atom and(2)α-C-H cleavage by AuNPs,yielding AC and adsorbed water.Molecular O_(2)adsorbs in the oxygen vacancy(O_(V))formed by water removal,generating a peroxide anion(O_(2)^(2-))as the activated oxygen species.In the second part of the catalytic cycle,the basic O_(2)^(2-)species abstracts the H atom from another ethanol molecule,followed byα-C-H cleavage by AuNPs,AC production,and water removal.Water formation in the second part of the catalytic cycle is the rate-controlling step for Au/LaMnO_(3)and Au/LaMnCuO_(3)models.Moderate Cu doping enhances the essential Cu^(+)-OV-Mn^(2+)sites and lowers the barrier for water formation due to the weaker Cu-O bond than the Mn-O bond.In contrast,excessive Cu doping creates unstable Cu^(2+)-O-Cu^(2+)sites and shifts the barrier to theα-C-H cleavage.展开更多
Fuel cells are one of the most promising clean energy devices to substitute for fossil fuel in the future to alleviate energy crisis and environmental pollution.As the key reaction on the cathode in the fuel cells,oxy...Fuel cells are one of the most promising clean energy devices to substitute for fossil fuel in the future to alleviate energy crisis and environmental pollution.As the key reaction on the cathode in the fuel cells,oxygen reduction reaction(ORR)still requires efficient noble metal catalysts such as the comme rcial Pt/C to boost the reaction for its sluggish kinetics.Therefore,it is critical to design earth-abundant carbonbased catalysts with high efficiency and long-term stability to replace the noble metal-based catalysts.This review focuses on the recent progress about carbon-based ORR catalysts including non-metal doped carbon materials,transition metal-nitrogen-carbon species,transition metal carbides/carbon,single atom catalysts,and other carbon hybrids.And we further infer that the excellent ORR performances can be achieved by the balance of geometric and electronic structures of catalysts such as conductivity,surface area,hierarchical porous structure,defect and doping effect.Additionally,the perspective development trend is also proposed to guide the rational designation of carbon-based catalysts for ORR and even extend to other energy storage and conversion fields in the future.展开更多
Dimethylation of histone H3 lysine 9 （H3K9me2） is an important epigenetic mark associated with transcription repression. Here, we identified PHF8, a JmjC-domain-containing protein, as a histone demethylase specific ...Dimethylation of histone H3 lysine 9 （H3K9me2） is an important epigenetic mark associated with transcription repression. Here, we identified PHF8, a JmjC-domain-containing protein, as a histone demethylase specific for this repressing mark. Recombinant full-length wild type protein could remove methylation from H3K9me2, but mutation of a conserved histidine to alanine H247A abolished the demethylase activity. Overexpressed exogenous PHF8 was colocalized with B23 staining. Endogenous PHF8 was also colocalized with B23 and fibrillarin, two well-established nucleolus proteins, suggesting that PHF8 is localized in the nucleolus and may regulate rRNA transcription. Indeed, PHF8 bound to the promoter region of the rDNA gene. Knockdown of PHF8 reduced the expression of rRNA, and overexpression of the gene resulted in upregulation of rRNA transcript. Concomitantly, H3K9me2 level was elevated in the promoter region of the rDNA gene in PHF8 knockdown cells and reduced significantly when the wild type but not the catalytically inactive H247A mutant PHF8 was overexpressed. Thus, our study identified a histone demethylase for H3K9me2 that regulates rRNA transcription.展开更多
In recent years,the close relationship between uranium and Ti-Fe oxides in the sandstonetype uranium deposits has been extensively recognized.However,the altered characteristics of ilmenite and its relationship with u...In recent years,the close relationship between uranium and Ti-Fe oxides in the sandstonetype uranium deposits has been extensively recognized.However,the altered characteristics of ilmenite and its relationship with uranium enrichment still remain unclear.With this paper based on heavymineral sorting of uranium ore selected from the Tarangaole-Nalinggou deposit in the northeastern Ordos Basin,electron probe,backscattering image,energy spectrum and scanning electron microscopy were systematically performed.The ilmenite in the sandstone can be divided into four groups,including unaltered,weakly altered,moderately altered,and strongly altered ilmenite.The alteration of ilmenite in uranium ores is notably more intense than that of the surrounding rocks.In addition,weakly,moderately,and strongly altered ilmenite associated with uranium minerals in uranium ores demonstrate that the more intensity ilmenite altered,the closer its relationship with uranium minerals is.The ilmenite has likely been somewhat altered before mineralization,and the alteration intensifies by later exposure related to an oxygencontaining fluid.The alteration mechanism comprises a process of competitive diffusion between Fe^(2+)and O_(2)-ions.In the early stage,Fe ions was mainly diffused on the particle surface.Subsequently,diffusion of O ions into the particles began to be dominate.Most of the leached iron is stripped or carried away by fluid.In an alkaline and reductive environment,the remaining iron is reduced to form the surrounding pyrite,and TiO_(2)in a form of titanium sol recrystallizes(i.e.,anatase).Backscattering images show that uranium and altered ilmenite are close in space.Coffinite is often distributed along the edges of altered ilmenite as burrs in shape.Colloidal or knitted coffinite associated with anatase is formed in the voids of altered ilmenite.The chemical composition of altered ilmenite varies considerably from the core to edge,and the mineral assemblage sequence is from girdle with ilmenite,to leucosphenite,to anatase,and to coffinite.There is no brannerite that is symbiotic with altered ilmenite.It is considered to be a uranium-containing titanium mineral aggregate caused by the reduction and adsorption of uranium.As the altered product of ilmenite,TiO_(2)is an aggregation agent,increasing the concentration of uranium by adsorption.Together with Fe^(2+)and S_(2)-in secondary pyrite,this aggregate creates a uranium-rich environment in the microzone for the formation of coffinite.Therefore,the alteration of ilmenite plays a geochemical role in the processes of sedimentary,diagenesis and mineralization,in which Fe is removed,Ti is enriched,and U is adsorbed and reduced.展开更多
In the continental basins of Northern China(NC),a series of energy resources commonly co-exist in the same basin.As the three typical superimposed basins of different genesis in the NC,the Junggar,Ordos,and Songliao b...In the continental basins of Northern China(NC),a series of energy resources commonly co-exist in the same basin.As the three typical superimposed basins of different genesis in the NC,the Junggar,Ordos,and Songliao basins were chosen as the research objects.The favorable uraniumbearing structures are generally shown as a basin-margin slope or transition belt of uplifts with the development of faults,which are conducive to a fluid circulation system.The Hercynian,Indosinian,and Yanshanian movements resulted in the development of uranium-rich intrusions which acted as the significant uranium sources.The main hydrocarbon source rocks are developed in the Carboniferous,Permian,Jurassic and Cretaceous.The mature stage of source rocks is concentrated in the Jurassic–Cretaceous,followed by the multi-stage expulsion events.Influenced by the India-Eurasian collision and the subduction of the Pacific Plate,the tectonic transformation in the Late Yanshanian and Himalayan periods significantly influenced the sandstone-type uranium mineralization.The hydrocarbon reservoirs are spatially consistent with sandstone-type uranium deposits,while the hydrocarbon expulsion events occur in sequence with sandstone-type uranium mineralization.In the periphery of the faults or the uplifts,both fluids met and formed uranium concentration.The regional tectonic movements motivate the migration of hydrocarbon fluids and uranium mineralization,especially the Himalayan movement.展开更多
Dear editor,This letter puts forward a secure feedback control scheme to bipartite tracking consensus for a set of generic linear autonomous agents subject to aperiodic and unknown denial-of-service(Do S)attacks.
The Stopped-Rotor(SR)UAV combines the advantages of vertical take-off and landing of helicopter and high-speed cruise of fixed-wing aircraft.At the same time,it also has a unique aerodynamic layout,which leads to grea...The Stopped-Rotor(SR)UAV combines the advantages of vertical take-off and landing of helicopter and high-speed cruise of fixed-wing aircraft.At the same time,it also has a unique aerodynamic layout,which leads to great differences in the control and aerodynamic characteristics of various flight modes,and brings great challenges to the flight dynamics modelling and control in full-mode flight.In this paper,the flight dynamics modelling and control method of SR UAV in full-mode flight is studied.First,based on the typical flight profile of SR UAV when performing missions,using the theory and method of fuzzy mathematics,the T-S flight dynamics model of SR UAV in full-mode flight is established by synthesizing the flight dynamics model of each flight mode.Then,an explicit model tracking and parameter adjusting control system based on fuzzy theory is designed to enhance the stability of the inner loop of SR UAV in full-mode flight,which effectively reduces the coupling between axes and improves the control quality of the system.Finally,the outer loop control system is designed by using classical control method,and the control law of SR UAV in full-mode automatic flight is obtained.The simulation results show that the proposed control system design method is feasible and effective,which lays a solid foundation for the subsequent engineering implementation of the SR UAV.展开更多
Endogenous metabolites play key functions in many important physiological and biochemical processes.The comprehensive in situ detection and direct imaging of metabolites in bio-tissues by matrix-assisted laser desorpt...Endogenous metabolites play key functions in many important physiological and biochemical processes.The comprehensive in situ detection and direct imaging of metabolites in bio-tissues by matrix-assisted laser desorption/ionization mass spectrometry imaging(MALDI-MSI)is very important for understanding complex and diverse biological processes and has become an essential aspect of spatial omics.In this work,4-aminoazobenzene(AAB)was successfully screened and optimized as a new negative ion(-)MALDI matrix to enhance the in situ detection and imaging of metabolites in tissues using MALDIMSI.Obviously,AAB exhibited superior properties in terms of ultraviolet absorption,background ion interference,matrix morphology,and metabolite ionization efficiency.AAB was used for in situ detection and imaging of metabolites in rat brain and germinating Chinese yew seed tissue sections,where 264and 339 metabolite ion signals were successfully detected and imaged using(-)MALDI-MS,respectively.In addition,high-resolution imaging of mouse eyeball section using MALDI-tims TOF MSI with spatial resolution of up to 10μm was successfully carried out,showing that AAB is an efficient(-)MALDI matrix for capturing high-resolution images of metabolites in biological tissue sections.展开更多
Mesoporous carbon supported with transition metals nanoparticles performs desired activities for oxygen reduction reaction(ORR) and clean energy conversion devices such as Zn–air batteries. In this work,we synthesize...Mesoporous carbon supported with transition metals nanoparticles performs desired activities for oxygen reduction reaction(ORR) and clean energy conversion devices such as Zn–air batteries. In this work,we synthesized N-doped mesoporous carbon loaded with cobalt nanoparticles(CoMCN) through selfassembly method. There are sufficient mesopores on the carbon substrate which stem from the poreforming agent. These mesopores can provide enough accessible active sites and profitable charge/mass transport for ORR. The high content of pyridinic and graphitic N is beneficial for promoting O_(2) adsorption and reduction. The smaller value of ID/IGindicates the higher degree of graphitization of CoMCN,providing better electronic conductivity. The half-wave potential of CoMCN is 0.865 V in basic solution,which is 24 mV more positive than that of the commercial Pt/C(0.841 V). In addition, CoMCN performs excellent methanol tolerance and stability under both basic and acidic conditions. The Zn–air battery assembled with CoMCN performs the larger power density and open-circuit voltage than the commercial Pt/C-based battery, indicating the potential application in energy conversion systems. This work provides thoughtful ideas for fabricating transition metal nanoparticles based porous carbon for electrocatalysis and metal–air batteries.展开更多
Low-molecular-weight(LMW)compounds are ubiquitous in living organisms and play essential roles in biological processes.The direct analysis of LMW compounds in biological tissues by matrix-assisted laser desorption/ion...Low-molecular-weight(LMW)compounds are ubiquitous in living organisms and play essential roles in biological processes.The direct analysis of LMW compounds in biological tissues by matrix-assisted laser desorption/ionization mass spectrometry imaging(MALDI-MSI)could provide a more comprehensive understanding of their essential functions.Here,we evaluated 4-nitrocatechol(4-NC)as a novel positive-ion matrix for enhancing in situ detection and imaging of LMW compounds from the rat liver,brain,and germinating Chinese-yew seed by MALDI-MS.Our results showed that the 4-NC possessed remarkable features,including strong ultraviolet absorption,uniform matrix crystal,excellent chemical stability,and fewer matrix-related background peaks.The use of 4-NC led to the successful detection of 232,218,and193 LMW compounds from the three abovementioned tissue sections,respectively.Also,the use of 4-NC improved the imaging quality of LMW compounds in tissue sections through MALDI-MSI and has the potential as a matrix for MALDI tissue imaging of LMW compounds.展开更多
Among all the known electrode materials, vanadium pentoxide(V_(2)O_(5)) has high reversible capacity. It is a very valuable material for research of the complexity, rich structure and morphology. However, it also has ...Among all the known electrode materials, vanadium pentoxide(V_(2)O_(5)) has high reversible capacity. It is a very valuable material for research of the complexity, rich structure and morphology. However, it also has some disadvantages,such as poor cycle stability, low discharge voltage, low conductivity and Li^(+) diffusion coefficient. In this regard, researchers have carried out a lot of research, such as using various methods to improve the nanostructures, introducing heterostructures,introducing point defects or cation doping in the crystal structure, etc. The electrochemical performance of V_(2)O_(5)has been significantly improved in reversible capacity, high-rate capacity and long-term cycle stability. In this paper, V_(2)O_(5)based nanostructure with different chemical composition are briefly introduced, and it covers V_(2)O_(5)nanomaterials with different morphology, including 1D nanorods, nanobelts, nanotubes, 2D leaf like nanosheets and other nanosheets, and 3D hollow structures, porous nanostructures, porous eggshell microsphere structures. The composite nanomaterials of V_(2)O_(5)and different carbonaceous supports are also introduced. Finally, the V_(2)O_(5)composite materials doped with cations are discussed. The electrochemical performance of V_(2)O_(5)based electrode can be improved effectively by obtaining appropriate nanostructure and optimized chemical composition.展开更多
This paper investigates the attitude tracking control problem for the cruise mode of a dual-system convertible unmanned aerial vehicle(UAV)in the presence of parameter uncertainties,unmodeled uncertainties and wind di...This paper investigates the attitude tracking control problem for the cruise mode of a dual-system convertible unmanned aerial vehicle(UAV)in the presence of parameter uncertainties,unmodeled uncertainties and wind disturbances.First,a fixed-time disturbance observer(FXDO)based on the bi-limit homogeneity theory is designed to estimate the lumped disturbance of the convertible UAV model.Then,a fixed-time integral sliding mode control(FXISMC)is combined with the FXDO to achieve strong robustness and chattering reduction.Bi-limit homogeneity theory and Lyapunov theory are applied to provide detailed proof of the fixed-time stability.Finally,numerical simulation experimental results verify the robustness of the proposed algorithm to model parameter uncertainties and wind disturbances.In addition,the proposed algorithm is deployed in a open-source UAV autopilot and its effectiveness is further demonstrated by hardware-in-the-loop experimental results.展开更多
In order to explore the criminal psychological mechanism of burglars,this study adopts the qualitative research method of grounded theory to conduct in-depth interviews with 41 burglars in two prisons in Jiangxi Provi...In order to explore the criminal psychological mechanism of burglars,this study adopts the qualitative research method of grounded theory to conduct in-depth interviews with 41 burglars in two prisons in Jiangxi Province,China.Nvivo 11.0 was used to code-construct and qualitatively analyze the interview content in order to refine the influencing factors and psychological evolution process of burglary behavior.Thefindings revealed that(1)burglary risk factors include burglary cognition,burglary motivation,burglary decision-making,delinquent peers,burglary opportunity,and incomplete reformation.(2)There are three stages in the psychological evolution pro-cess of burglars:cognitive formation,motivational dominance,and behavioral decision.(3)The interpretation of the criminal psychological mechanism of burglars is a comprehensive and dynamic outcome of the interaction of internal and external factors that shape the individual.Participants’inspection and non-participants’inspection were adapted to verify the research results’validity,which showed that the results were reliable.展开更多
A theoretical and numerical study has been performed on an air film dumper attached to a plate structure. Combined with the analysis by Fox and Whittorg a damping model of the air fiim damper has been developed. A com...A theoretical and numerical study has been performed on an air film dumper attached to a plate structure. Combined with the analysis by Fox and Whittorg a damping model of the air fiim damper has been developed. A complex stiffness was introduced to represent the air pressure in the damper cavity. The stain energy and dissipated energy were integrated from the real part and imaginary part of the complex stiffness to determine the stiffness and damping. The response of the plate with the air film damper was considered by treating the air film as multiple discrete damping-stiffness elements using ANSYS.展开更多
Insight into the growth behavior and electronic regulation of platinum(Pt)on various transition metal supports is paramount in developing high-performing electrocatalysts for hydrogen evolution reactions(HER).Herein,w...Insight into the growth behavior and electronic regulation of platinum(Pt)on various transition metal supports is paramount in developing high-performing electrocatalysts for hydrogen evolution reactions(HER).Herein,we studied the influence of molybdenum-based supports(MoX,X=C,N,P,and S)on the growth behavior and electronic regulation of Pt.We found that the formation energy variations between Pt single atom and clusters on MoX supports play a pivotal role in the growth behavior of Pt.Moreover,the electronic regulation of Pt induced by metal-support interaction may reflect the valence changes of Pt in PtMoX/C.The Pt-MoC/C catalyst with a moderate valence state of Pt exhibits the best HER activity with an overpotential of 12.0 mV at 10 mA cm^(-2)and a mass activity of 27.1 A mg_(Pt)^(-)1,12.3 times as high as that of commercial 20 wt%Pt/C.This work provides constructive guidance for the design of high-performance HER catalysts.展开更多
This study aimed to comprehensively examine the association of gallstones,cholecystectomy,and cancer risk.Multivariable logistic regressions were performed to estimate the observational associations of gallstones and ...This study aimed to comprehensively examine the association of gallstones,cholecystectomy,and cancer risk.Multivariable logistic regressions were performed to estimate the observational associations of gallstones and cholecystectomy with cancer risk,using data from a nationwide cohort involving 239799 participants.General and gender-specific two-sample Mendelian randomization(MR)analysis was further conducted to assess the causalities of the observed associations.Observationally,a history of gallstones without cholecystectomy was associated with a high risk of stomach cancer(adjusted odds ratio(aOR)=2.54,95%confidence interval(CI)1.50–4.28),liver and bile duct cancer(aOR=2.46,95%CI 1.17–5.16),kidney cancer(aOR=2.04,95%CI 1.05–3.94),and bladder cancer(aOR=2.23,95%CI 1.01–5.13)in the general population,as well as cervical cancer(aOR=1.69,95%CI 1.12–2.56)in women.Moreover,cholecystectomy was associated with high odds of stomach cancer(aOR=2.41,95%CI 1.29–4.49),colorectal cancer(aOR=1.83,95%CI 1.18–2.85),and cancer of liver and bile duct(aOR=2.58,95%CI 1.11–6.02).MR analysis only supported the causal effect of gallstones on stomach,liver and bile duct,kidney,and bladder cancer.This study added evidence to the causal effect of gallstones on stomach,liver and bile duct,kidney,and bladder cancer,highlighting the importance of cancer screening in individuals with gallstones.展开更多
基金supported by the National Natural Science Foundation of China (Nos. 22171287, 51972342, 52303274)Taishan Scholar Project of Shandong Province (tsqn202103046 and ts20190922)+1 种基金Natural Science Foundation of Shandong Province (ZR2024QB076, ZR2022QE175)Fundamental Research Funds for the Central Universities (24CX07007A and 22CX01002A-1)
文摘Creating strongly coupled heterostructures with favorable catalytic activities is crucial for promoting the performance of catalytic reactions,especially those involve multiple intermediates.Herein,we fabricated a strongly coupled platinum/molybdenum nitrides nanocluster heterostructure on nitrogen-doped reduced graphene oxide(Pt/Mo_(2)N-NrGO)for alkaline hydrogen evolution reaction.The well-defined Pt-containing Anderson-type polyoxometalates promote strong interfacial Pt-N-Mo bonding in Pt/Mo_(2)N-NrGO,which exhibits a remarkably low overpotential,high mass activity,and exceptional long-term durability(>500 h at 1500 mA cm^(-2))in an anion-exchange membrane water electrolyzer(AEMWE).Operando Raman spectroscopy and density functional theory reveal that pronounced electronic coupling at the Pt/Mo_(2)N cluster interface facilitates the catalytic decomposition of H_(2)O through synergistic stabilization of intermediates(Pt-H^(*)and Mo-OH^(*)),thereby enhancing the kinetics of the rate-determining Volmer step.Techno-economic analysis indicates a levelized hydrogen production cost of$2.02 kg^(-1),meeting the US DOE targets.Our strategy presents a viable pathway to designing next-generation catalysts for industrial AEMWE for green hydrogen production.
文摘Gold nanoparticles(AuNPs)supported on the Cu-doped LaMnO_(3)perovskites exhibit strong Au-Mn-Cu synergy in the aerobic oxidation of gaseous ethanol to acetaldehyde(AC).The Au/LaMnCuO_(3)catalysts achieve AC yields exceeding 90%and a space-time yield of 715 g_(AC)g_(AU)^(-1)h^(-1)at 225℃,outperforming reported catalysts.The outstanding performance is attributed to adjacent Cu^(+)and Mn^(2+)ions in the perovskite surface,which,together with nearby AuNPs,contribute to the high activity and stability.The best-performing catalyst contains a Cu/Mn ratio of 1/3 in the perovskite.Doping too much Cu into the perovskite leads to metallic Cu,suppressing catalyst performance.Density functional theory(reaction energetics,electronic structure analysis)and microkinetics simulations aided in understanding the synergy between Cu and Mn and the role of AuNPs.The reaction involves two H abstraction steps:(1)O-H cleavage of adsorbed ethanol by the basic perovskite lattice oxygen atom and(2)α-C-H cleavage by AuNPs,yielding AC and adsorbed water.Molecular O_(2)adsorbs in the oxygen vacancy(O_(V))formed by water removal,generating a peroxide anion(O_(2)^(2-))as the activated oxygen species.In the second part of the catalytic cycle,the basic O_(2)^(2-)species abstracts the H atom from another ethanol molecule,followed byα-C-H cleavage by AuNPs,AC production,and water removal.Water formation in the second part of the catalytic cycle is the rate-controlling step for Au/LaMnO_(3)and Au/LaMnCuO_(3)models.Moderate Cu doping enhances the essential Cu^(+)-OV-Mn^(2+)sites and lowers the barrier for water formation due to the weaker Cu-O bond than the Mn-O bond.In contrast,excessive Cu doping creates unstable Cu^(2+)-O-Cu^(2+)sites and shifts the barrier to theα-C-H cleavage.
基金supported by the National Natural Science Foundation of China(Nos.21675147 and 21802003)the Jilin Provincial Science and Technology Development Program(Nos.20190201242JC,20180520142JH)the China Postdoctoral Science Foundation(No.2018M631239)。
文摘Fuel cells are one of the most promising clean energy devices to substitute for fossil fuel in the future to alleviate energy crisis and environmental pollution.As the key reaction on the cathode in the fuel cells,oxygen reduction reaction(ORR)still requires efficient noble metal catalysts such as the comme rcial Pt/C to boost the reaction for its sluggish kinetics.Therefore,it is critical to design earth-abundant carbonbased catalysts with high efficiency and long-term stability to replace the noble metal-based catalysts.This review focuses on the recent progress about carbon-based ORR catalysts including non-metal doped carbon materials,transition metal-nitrogen-carbon species,transition metal carbides/carbon,single atom catalysts,and other carbon hybrids.And we further infer that the excellent ORR performances can be achieved by the balance of geometric and electronic structures of catalysts such as conductivity,surface area,hierarchical porous structure,defect and doping effect.Additionally,the perspective development trend is also proposed to guide the rational designation of carbon-based catalysts for ORR and even extend to other energy storage and conversion fields in the future.
基金Acknowledgments We thank the cell biology core facility for confocal study. The PHF8 antibody was kindly provided by Dr Jiemin Wong （East China Normal University）. This work was supported by the National Basic Research Program of China （2007CB947900, 2010CB529705, 2007CB947100）, the Chinese Academy of Sci- ences （KSCX2-YW-R-04, KSCX2-YW-R-I 11）, the National Natural Science Foundation of China （30870538, 90919026）, Postdoctoral fellowship （20090460670）, and the Council of Shanghai Municipal Government for Science and Technology.
文摘Dimethylation of histone H3 lysine 9 （H3K9me2） is an important epigenetic mark associated with transcription repression. Here, we identified PHF8, a JmjC-domain-containing protein, as a histone demethylase specific for this repressing mark. Recombinant full-length wild type protein could remove methylation from H3K9me2, but mutation of a conserved histidine to alanine H247A abolished the demethylase activity. Overexpressed exogenous PHF8 was colocalized with B23 staining. Endogenous PHF8 was also colocalized with B23 and fibrillarin, two well-established nucleolus proteins, suggesting that PHF8 is localized in the nucleolus and may regulate rRNA transcription. Indeed, PHF8 bound to the promoter region of the rDNA gene. Knockdown of PHF8 reduced the expression of rRNA, and overexpression of the gene resulted in upregulation of rRNA transcript. Concomitantly, H3K9me2 level was elevated in the promoter region of the rDNA gene in PHF8 knockdown cells and reduced significantly when the wild type but not the catalytically inactive H247A mutant PHF8 was overexpressed. Thus, our study identified a histone demethylase for H3K9me2 that regulates rRNA transcription.
基金financially supported by projects under the National Key Research and Development Program of China(No.2018YFC0604200)the Open Fund Project of State Key Laboratory of Nuclear Resources and Environment (No.2020NRE10)+3 种基金the National Key Infrastructure Development Plan (No.2015CB453006)the China Geological Survey (Nos.DD20190119,DD20221678)the International Geoscience Programme (No.IGCP-675)the National Nature Science Foundation of China (No.92162212)
文摘In recent years,the close relationship between uranium and Ti-Fe oxides in the sandstonetype uranium deposits has been extensively recognized.However,the altered characteristics of ilmenite and its relationship with uranium enrichment still remain unclear.With this paper based on heavymineral sorting of uranium ore selected from the Tarangaole-Nalinggou deposit in the northeastern Ordos Basin,electron probe,backscattering image,energy spectrum and scanning electron microscopy were systematically performed.The ilmenite in the sandstone can be divided into four groups,including unaltered,weakly altered,moderately altered,and strongly altered ilmenite.The alteration of ilmenite in uranium ores is notably more intense than that of the surrounding rocks.In addition,weakly,moderately,and strongly altered ilmenite associated with uranium minerals in uranium ores demonstrate that the more intensity ilmenite altered,the closer its relationship with uranium minerals is.The ilmenite has likely been somewhat altered before mineralization,and the alteration intensifies by later exposure related to an oxygencontaining fluid.The alteration mechanism comprises a process of competitive diffusion between Fe^(2+)and O_(2)-ions.In the early stage,Fe ions was mainly diffused on the particle surface.Subsequently,diffusion of O ions into the particles began to be dominate.Most of the leached iron is stripped or carried away by fluid.In an alkaline and reductive environment,the remaining iron is reduced to form the surrounding pyrite,and TiO_(2)in a form of titanium sol recrystallizes(i.e.,anatase).Backscattering images show that uranium and altered ilmenite are close in space.Coffinite is often distributed along the edges of altered ilmenite as burrs in shape.Colloidal or knitted coffinite associated with anatase is formed in the voids of altered ilmenite.The chemical composition of altered ilmenite varies considerably from the core to edge,and the mineral assemblage sequence is from girdle with ilmenite,to leucosphenite,to anatase,and to coffinite.There is no brannerite that is symbiotic with altered ilmenite.It is considered to be a uranium-containing titanium mineral aggregate caused by the reduction and adsorption of uranium.As the altered product of ilmenite,TiO_(2)is an aggregation agent,increasing the concentration of uranium by adsorption.Together with Fe^(2+)and S_(2)-in secondary pyrite,this aggregate creates a uranium-rich environment in the microzone for the formation of coffinite.Therefore,the alteration of ilmenite plays a geochemical role in the processes of sedimentary,diagenesis and mineralization,in which Fe is removed,Ti is enriched,and U is adsorbed and reduced.
基金jointly supported by the National Key Research and Development Program of China (No.2018YFC0604200)the National Science Foundation of China (Nos.92162212,41502195)+2 种基金the International Geoscience Programme (No.GCP-675)the Open Fund Project of State Key Laboratory of Nuclear Resources and Environment (No.2020NRE10)the Geological Survey Project of China Geological Survey (Nos.DD20190121,DD20190119,DD20211191,and DD20221678)
文摘In the continental basins of Northern China(NC),a series of energy resources commonly co-exist in the same basin.As the three typical superimposed basins of different genesis in the NC,the Junggar,Ordos,and Songliao basins were chosen as the research objects.The favorable uraniumbearing structures are generally shown as a basin-margin slope or transition belt of uplifts with the development of faults,which are conducive to a fluid circulation system.The Hercynian,Indosinian,and Yanshanian movements resulted in the development of uranium-rich intrusions which acted as the significant uranium sources.The main hydrocarbon source rocks are developed in the Carboniferous,Permian,Jurassic and Cretaceous.The mature stage of source rocks is concentrated in the Jurassic–Cretaceous,followed by the multi-stage expulsion events.Influenced by the India-Eurasian collision and the subduction of the Pacific Plate,the tectonic transformation in the Late Yanshanian and Himalayan periods significantly influenced the sandstone-type uranium mineralization.The hydrocarbon reservoirs are spatially consistent with sandstone-type uranium deposits,while the hydrocarbon expulsion events occur in sequence with sandstone-type uranium mineralization.In the periphery of the faults or the uplifts,both fluids met and formed uranium concentration.The regional tectonic movements motivate the migration of hydrocarbon fluids and uranium mineralization,especially the Himalayan movement.
基金supported in part by the National Science Foundation of China (U1830207, 61772003, 6190 3066)the Natural Science Foundation of Sichuan Province (2022 NSFSC0878)+3 种基金the National Postdoctoral Program for Innovative Talents (BX2021056)the Sichuan Science and Technology Program (2021YFH0042)the National Natural Science Foundation of China (6210021010)the funding from Shenzhen Institute of Artificial Intelligence and Robotics for Society。
文摘Dear editor,This letter puts forward a secure feedback control scheme to bipartite tracking consensus for a set of generic linear autonomous agents subject to aperiodic and unknown denial-of-service(Do S)attacks.
基金the Natural Science Foundation of China (No. 12102345)the Natural Science Basic Research Program of Shaanxi Province (Nos. 2021JQ-086 and 2021JQ076)Taicang Scientific Research Institute Innovation Leading Special Plan (No. tc2019dyds11)
文摘The Stopped-Rotor(SR)UAV combines the advantages of vertical take-off and landing of helicopter and high-speed cruise of fixed-wing aircraft.At the same time,it also has a unique aerodynamic layout,which leads to great differences in the control and aerodynamic characteristics of various flight modes,and brings great challenges to the flight dynamics modelling and control in full-mode flight.In this paper,the flight dynamics modelling and control method of SR UAV in full-mode flight is studied.First,based on the typical flight profile of SR UAV when performing missions,using the theory and method of fuzzy mathematics,the T-S flight dynamics model of SR UAV in full-mode flight is established by synthesizing the flight dynamics model of each flight mode.Then,an explicit model tracking and parameter adjusting control system based on fuzzy theory is designed to enhance the stability of the inner loop of SR UAV in full-mode flight,which effectively reduces the coupling between axes and improves the control quality of the system.Finally,the outer loop control system is designed by using classical control method,and the control law of SR UAV in full-mode automatic flight is obtained.The simulation results show that the proposed control system design method is feasible and effective,which lays a solid foundation for the subsequent engineering implementation of the SR UAV.
基金supported by the National Natural Science Foundation of China(Nos.31770384 and 21605164)the Youth Academic Team Project of MUC(No.10301-02200301)+1 种基金the Huayi Technology Innovation Center for Research Resources(No.HTIC P01RR2017001A)the Key Laboratory Construction Funds of State Ethnic Affairs Commission of China(No.10301-02200303)。
文摘Endogenous metabolites play key functions in many important physiological and biochemical processes.The comprehensive in situ detection and direct imaging of metabolites in bio-tissues by matrix-assisted laser desorption/ionization mass spectrometry imaging(MALDI-MSI)is very important for understanding complex and diverse biological processes and has become an essential aspect of spatial omics.In this work,4-aminoazobenzene(AAB)was successfully screened and optimized as a new negative ion(-)MALDI matrix to enhance the in situ detection and imaging of metabolites in tissues using MALDIMSI.Obviously,AAB exhibited superior properties in terms of ultraviolet absorption,background ion interference,matrix morphology,and metabolite ionization efficiency.AAB was used for in situ detection and imaging of metabolites in rat brain and germinating Chinese yew seed tissue sections,where 264and 339 metabolite ion signals were successfully detected and imaged using(-)MALDI-MS,respectively.In addition,high-resolution imaging of mouse eyeball section using MALDI-tims TOF MSI with spatial resolution of up to 10μm was successfully carried out,showing that AAB is an efficient(-)MALDI matrix for capturing high-resolution images of metabolites in biological tissue sections.
基金financial support from the National Natural Science Foundation of China (Nos. 21974097 and 21675147)he Education Department of Guangdong Province (Nos. 2020KSYS004 and 2020ZDZX2015)+1 种基金Science and Technology Bureau of Jiangmen (No. 2019030102360012639)the Science Foundation for High-Level Talents of Wuyi University (No. 2018RC50)。
文摘Mesoporous carbon supported with transition metals nanoparticles performs desired activities for oxygen reduction reaction(ORR) and clean energy conversion devices such as Zn–air batteries. In this work,we synthesized N-doped mesoporous carbon loaded with cobalt nanoparticles(CoMCN) through selfassembly method. There are sufficient mesopores on the carbon substrate which stem from the poreforming agent. These mesopores can provide enough accessible active sites and profitable charge/mass transport for ORR. The high content of pyridinic and graphitic N is beneficial for promoting O_(2) adsorption and reduction. The smaller value of ID/IGindicates the higher degree of graphitization of CoMCN,providing better electronic conductivity. The half-wave potential of CoMCN is 0.865 V in basic solution,which is 24 mV more positive than that of the commercial Pt/C(0.841 V). In addition, CoMCN performs excellent methanol tolerance and stability under both basic and acidic conditions. The Zn–air battery assembled with CoMCN performs the larger power density and open-circuit voltage than the commercial Pt/C-based battery, indicating the potential application in energy conversion systems. This work provides thoughtful ideas for fabricating transition metal nanoparticles based porous carbon for electrocatalysis and metal–air batteries.
基金supported by the National Natural Science Foundation of China(Nos.31770384 and 21605164)the Youth Academic Team Project of MUC(No.10301-02200301)+1 种基金the Huayi Technology Innovation Center for Research Resources(No.HTIC P01RR2017001A)the Key Laboratory Construction Funds of State Ethnic Affairs Commission of China(No.10301-02200303)。
文摘Low-molecular-weight(LMW)compounds are ubiquitous in living organisms and play essential roles in biological processes.The direct analysis of LMW compounds in biological tissues by matrix-assisted laser desorption/ionization mass spectrometry imaging(MALDI-MSI)could provide a more comprehensive understanding of their essential functions.Here,we evaluated 4-nitrocatechol(4-NC)as a novel positive-ion matrix for enhancing in situ detection and imaging of LMW compounds from the rat liver,brain,and germinating Chinese-yew seed by MALDI-MS.Our results showed that the 4-NC possessed remarkable features,including strong ultraviolet absorption,uniform matrix crystal,excellent chemical stability,and fewer matrix-related background peaks.The use of 4-NC led to the successful detection of 232,218,and193 LMW compounds from the three abovementioned tissue sections,respectively.Also,the use of 4-NC improved the imaging quality of LMW compounds in tissue sections through MALDI-MSI and has the potential as a matrix for MALDI tissue imaging of LMW compounds.
基金Project supported by the National Natural Science Foundation of China (Grant Nos. 51702097 and U1804125)the Key Scientific and Technological Research Projects of Henan Province, China (Grant No. 202102210222)。
文摘Among all the known electrode materials, vanadium pentoxide(V_(2)O_(5)) has high reversible capacity. It is a very valuable material for research of the complexity, rich structure and morphology. However, it also has some disadvantages,such as poor cycle stability, low discharge voltage, low conductivity and Li^(+) diffusion coefficient. In this regard, researchers have carried out a lot of research, such as using various methods to improve the nanostructures, introducing heterostructures,introducing point defects or cation doping in the crystal structure, etc. The electrochemical performance of V_(2)O_(5)has been significantly improved in reversible capacity, high-rate capacity and long-term cycle stability. In this paper, V_(2)O_(5)based nanostructure with different chemical composition are briefly introduced, and it covers V_(2)O_(5)nanomaterials with different morphology, including 1D nanorods, nanobelts, nanotubes, 2D leaf like nanosheets and other nanosheets, and 3D hollow structures, porous nanostructures, porous eggshell microsphere structures. The composite nanomaterials of V_(2)O_(5)and different carbonaceous supports are also introduced. Finally, the V_(2)O_(5)composite materials doped with cations are discussed. The electrochemical performance of V_(2)O_(5)based electrode can be improved effectively by obtaining appropriate nanostructure and optimized chemical composition.
基金supported by National Natural Science Foundation of China (Grant Nos.52072309 and 62303379)Beijing Institute of Spacecraft System Engineering Research Project (Grant NO.JSZL2020203B004)+1 种基金Natural Science Foundation of Shaanxi Province,Chinese (Grant NOs.2023-JC-QN-0003 and 2023-JC-QN-0665)Industry-University-Research Innovation Fund of Ministry of Education for Chinese Universities (Grant NO.2022IT189)。
文摘This paper investigates the attitude tracking control problem for the cruise mode of a dual-system convertible unmanned aerial vehicle(UAV)in the presence of parameter uncertainties,unmodeled uncertainties and wind disturbances.First,a fixed-time disturbance observer(FXDO)based on the bi-limit homogeneity theory is designed to estimate the lumped disturbance of the convertible UAV model.Then,a fixed-time integral sliding mode control(FXISMC)is combined with the FXDO to achieve strong robustness and chattering reduction.Bi-limit homogeneity theory and Lyapunov theory are applied to provide detailed proof of the fixed-time stability.Finally,numerical simulation experimental results verify the robustness of the proposed algorithm to model parameter uncertainties and wind disturbances.In addition,the proposed algorithm is deployed in a open-source UAV autopilot and its effectiveness is further demonstrated by hardware-in-the-loop experimental results.
基金Supported by the National Key Research and Development Program of China(2018YFC0831002).
文摘In order to explore the criminal psychological mechanism of burglars,this study adopts the qualitative research method of grounded theory to conduct in-depth interviews with 41 burglars in two prisons in Jiangxi Province,China.Nvivo 11.0 was used to code-construct and qualitatively analyze the interview content in order to refine the influencing factors and psychological evolution process of burglary behavior.Thefindings revealed that(1)burglary risk factors include burglary cognition,burglary motivation,burglary decision-making,delinquent peers,burglary opportunity,and incomplete reformation.(2)There are three stages in the psychological evolution pro-cess of burglars:cognitive formation,motivational dominance,and behavioral decision.(3)The interpretation of the criminal psychological mechanism of burglars is a comprehensive and dynamic outcome of the interaction of internal and external factors that shape the individual.Participants’inspection and non-participants’inspection were adapted to verify the research results’validity,which showed that the results were reliable.
文摘A theoretical and numerical study has been performed on an air film dumper attached to a plate structure. Combined with the analysis by Fox and Whittorg a damping model of the air fiim damper has been developed. A complex stiffness was introduced to represent the air pressure in the damper cavity. The stain energy and dissipated energy were integrated from the real part and imaginary part of the complex stiffness to determine the stiffness and damping. The response of the plate with the air film damper was considered by treating the air film as multiple discrete damping-stiffness elements using ANSYS.
基金supported by the National Natural Science Foundation of China(22171287,51972342,52303274,51902345)the Taishan Scholar Project of Shandong Province(tsqn202103046 and ts20190922)+1 种基金the Natural Science Foundation of Shandong Province(ZR2022QE175)the Fundamental Research Funds for the Central Universities(24CX07007A and 22CX01002A-1)。
文摘Insight into the growth behavior and electronic regulation of platinum(Pt)on various transition metal supports is paramount in developing high-performing electrocatalysts for hydrogen evolution reactions(HER).Herein,we studied the influence of molybdenum-based supports(MoX,X=C,N,P,and S)on the growth behavior and electronic regulation of Pt.We found that the formation energy variations between Pt single atom and clusters on MoX supports play a pivotal role in the growth behavior of Pt.Moreover,the electronic regulation of Pt induced by metal-support interaction may reflect the valence changes of Pt in PtMoX/C.The Pt-MoC/C catalyst with a moderate valence state of Pt exhibits the best HER activity with an overpotential of 12.0 mV at 10 mA cm^(-2)and a mass activity of 27.1 A mg_(Pt)^(-)1,12.3 times as high as that of commercial 20 wt%Pt/C.This work provides constructive guidance for the design of high-performance HER catalysts.
基金funded by the National Natural Science Foundation of China(Nos.82270859,82370819,and 82088102)the National Key R&D Program of China(No.2023YFC2506700)+1 种基金the Shanghai Municipal Government grant(No.22Y31900300)the Shanghai Clinical Research Center for Metabolic Diseases(No.19MC1910100).
文摘This study aimed to comprehensively examine the association of gallstones,cholecystectomy,and cancer risk.Multivariable logistic regressions were performed to estimate the observational associations of gallstones and cholecystectomy with cancer risk,using data from a nationwide cohort involving 239799 participants.General and gender-specific two-sample Mendelian randomization(MR)analysis was further conducted to assess the causalities of the observed associations.Observationally,a history of gallstones without cholecystectomy was associated with a high risk of stomach cancer(adjusted odds ratio(aOR)=2.54,95%confidence interval(CI)1.50–4.28),liver and bile duct cancer(aOR=2.46,95%CI 1.17–5.16),kidney cancer(aOR=2.04,95%CI 1.05–3.94),and bladder cancer(aOR=2.23,95%CI 1.01–5.13)in the general population,as well as cervical cancer(aOR=1.69,95%CI 1.12–2.56)in women.Moreover,cholecystectomy was associated with high odds of stomach cancer(aOR=2.41,95%CI 1.29–4.49),colorectal cancer(aOR=1.83,95%CI 1.18–2.85),and cancer of liver and bile duct(aOR=2.58,95%CI 1.11–6.02).MR analysis only supported the causal effect of gallstones on stomach,liver and bile duct,kidney,and bladder cancer.This study added evidence to the causal effect of gallstones on stomach,liver and bile duct,kidney,and bladder cancer,highlighting the importance of cancer screening in individuals with gallstones.
