Incorporating ceramic particles into metal matrices is a proven strategy for boosting mechanical properties and wear resistance.The reinforcement potential of tungsten carbide(WC)particles in 316L stainless steel is r...Incorporating ceramic particles into metal matrices is a proven strategy for boosting mechanical properties and wear resistance.The reinforcement potential of tungsten carbide(WC)particles in 316L stainless steel is revealed,utilizing selective laser melting(SLM)to fabricate composites with 5 and 10 vol.%WC.The WC incorporation markedly alters the composite’s microstructure and mechanical attributes.Notably,5 vol.%WC-316L composite exhibits a refined submicron cellular structure,averaging 0.67μm in grain size.Elemental diffusion at WC-316L interface formed a 0.8μm gradient transition layer enriched with M_(2)C carbides(Fe,Cr,W),ensuring robust metallurgical bonding.Compared with unreinforced 316L,5%WC composite exhibits a 70%increase in tensile strength,reaching 1012.6 MPa,and a 25.3%rise in hardness,while maintaining acceptable ductility.10%WC composite achieves a 70.8%hardness enhancement,albeit with reduced elongation.Friction coefficient is reduced by up to 17.3%,and the wear mechanism shifts from adhesive to abrasive,significantly improving wear resistance.展开更多
The COVID-19 lockdown was a typical example of extreme emission reduction,providing an opportunity to study the impact of lockdown measures on air pollution.Particle number concentrations(PNC)originate from direct emi...The COVID-19 lockdown was a typical example of extreme emission reduction,providing an opportunity to study the impact of lockdown measures on air pollution.Particle number concentrations(PNC)originate from direct emissions or through new particle formation events.However,their variations during the lockdown period are under investigation.This study focuses on Luohe,a city on the southern edge of the North China Plain,analyzing the changes in PNC and its sources before,during,and after the COVID-19 lockdown.From March 25^(th)to May 31^(st),2022,real-time PNC measurements were conducted using a Scanning Mobility Particle Sizer for particle size.Results showed an 11.2%decrease in PNC during the lockdown compared to pre-lockdown and a 3.6%decrease compared to post-lockdown,indicating reduced local emissions and weakened regional transportation during the lockdown.Positive Matrix Factorization analysis identified six sources contributing to the total PNC,including photochemical nucleation,aged photochemical nucleation,gasoline vehicle emissions,diesel vehicle emissions,coal and biomass combustion,and secondary aerosols.The significant changes in source emissions indicate a substantially reduced traffic volume after the implementation of lockdown measures(2644.8#/cm^(3),2202.2#/cm^(3),2792.7#/cm^(3)).Concurrently,photochemical nucleation(310.1#/cm^(3),306.3#/cm^(3),393.1#/cm^(3))and photochemical nucleation aging(592.8#/cm^(3),744.1#/cm^(3),810.7#/cm^(3))exhibited increasing trends,while coal/biomass combustion(1656.6#/cm^(3),1586.2#/cm^(3),980.0#/cm^(3))and secondary sources(999.4#/cm^(3),791.1#/cm^(3),804.1#/cm^(3))showed decreasing trends.In summary,the contributions of traffic emissions to PNC highlight the potential for targeted traffic management strategies to improve urban air quality.展开更多
In comparison with their 2D and 3D counterparts,1D covalent organic frameworks(COFs)have rarely been investigated due to the synthetic challenge arising from the strict necessary matching in the molecular symmetry bet...In comparison with their 2D and 3D counterparts,1D covalent organic frameworks(COFs)have rarely been investigated due to the synthetic challenge arising from the strict necessary matching in the molecular symmetry between corresponding building blocks and linking units in addition to the unmanageable packing of 1D organic chains once formed.Herein,two novel imide-linked 1D COFs with phthalocyanine building blocks,namely NiPc-CZDM-COF and NiPc-CZDL-COF,were fabricated from the hydrothermal synthesis reaction of 2,3,9,10,16,17,23,24-octacarboxyphthalocyaninato nickel(II)(NiPc(COOH)_(8))with 9H-carbazole-3,6-diamine(CZDM)and 4,4′-(9H-carbazole-3,6-diyl)dianiline(CZDL),respectively.Two COFs have high crystallinity on the basis of powder X-ray diffraction analysis and high-resolution transmission electron microscopy.Due to their high ratio of exposed active centers on the edge sites of porous ribbons,both NiPc-CZDM-COF and NiPc-CZDL-COF electrodes display high utilization efficiency of NiPc electroactive sites of 8.0%and 7.5% according to the electrochemical measurement,resulting in their excellent capacity toward electrocatalytic nitrate reduction with the nitrate-to-NH3 Faradaic efficiency of nearly 100%.In particular,NiPc-CZDM-COF electrode exhibits superior electrocatalytic performance with high NH_(3) partial current density of−246 mA/cm^(2),ammonia yield rate of 19.5 mg cm^(−2) h^(−1),and turnover frequency of 5.8 s^(−1) at−1.2 V in an H-type cell associated with its higher conductivity.This work reveals the good potential of 1D porous crystalline materials in electrocatalysis.展开更多
The performance of lithium-sulfur batteries(LSBs)is severely limited by a detrimental negative feedback loop:sluggish polysulfide conversion kinetics lead to Li_(2)S accumulation,which further hinders lithiumion trans...The performance of lithium-sulfur batteries(LSBs)is severely limited by a detrimental negative feedback loop:sluggish polysulfide conversion kinetics lead to Li_(2)S accumulation,which further hinders lithiumion transport and exacerbates capacity decay.To address this,we propose a positive feedback strategy that simultaneously enhances lithium polysulfides(LiPSs)conversion and lithium-ion diffusion through a rationally designed separator.By modifying the separator with phosphorus-doped two-dimensional hollow holey carbon nanosheets(Hollow HCNS),we establish an interconnected network where rapid LiPSs confinement and conversion within the hollow cavities promote efficient lithium-ion transport,while the improved ion flux further accelerates reaction kinetics.This mutual reinforcement mechanism ensures stable cycling by suppressing the shuttle effect and promoting uniform Li_(2)S deposition,as verified by in situ spectroscopic and electrochemical analysis.The resulting LSBs exhibit high-rate capability,ultralow capacity decay,and exceptional stability under high sulfur loading.This work presents a general approach to overcoming the persistent negative feedback problem in high-energy battery systems by synergistically optimizing catalytic conversion and ionic transport.展开更多
LiNi_(0.8)Co_(0.1)Mn_(0.1)O_(2)(NCM811)layered oxides have been regarded as promising alternative cathodes for the next generation of high-energy lithium ion batteries(LIBs)due to high discharge capacities and energy ...LiNi_(0.8)Co_(0.1)Mn_(0.1)O_(2)(NCM811)layered oxides have been regarded as promising alternative cathodes for the next generation of high-energy lithium ion batteries(LIBs)due to high discharge capacities and energy densities at high operation voltage.However,the capacity fading under high operation voltage still restricts the practical application.Herein,the capacity degradation mechanism of NCM811 at atomic-scale is studied in detail under various cut-off voltages using aberration-corrected scanning transmission electron microscopy(STEM).It is observed that the crystal structure of NCM811 evolution from a layered structure to a rock-salt phase is directly accompanied by serious intergranular cracks under 4.9 V,which is distinguished from the generally accepted structure evolution of layered,disordered layered,defect rock salt and rock salt phases,also observed under 4.3 and 4.7 V.The electron energy loss spectroscopy analysis also confirms the reduction of Ni and Co from the surface to the bulk,not the previously reported only Li/Ni interlayer mixing.The degradation mechanism of NCM811 at a high cut-off voltage of4.9 V is attributed to the formation of intergranular cracks induced by defects,the direct formation of the rock salt phase,and the accompanied reduction of Ni^(2+)and Co^(2+)phases from the surface to the bulk.展开更多
In this article, the effect of diethylaluminum chloride （DEAC） in propylene polymerization with MgC12-supported Ziegler-Natta catalyst was studied. Addition of DEAC in the catalyst system caused evident change in ca...In this article, the effect of diethylaluminum chloride （DEAC） in propylene polymerization with MgC12-supported Ziegler-Natta catalyst was studied. Addition of DEAC in the catalyst system caused evident change in catalytic activity and polymer chain structure. The activity decrease in raising DEAC/Ti molar ratio from 0 to 2 is a result of depressed production of isotactic polypropylene chains. The number of active centers in fractions of each polymer sample was determined by quenching the polymerization with 2-thiophenecarbonyl chloride and fractionating the polymer into isotactic, medium- isotactic and atactic fractions. The number of active centers in isotactic fraction （[Ci＊]/[Ti]） was lowered by increasing DEAC/Ti molar ratio to 2, but further increasing the DEAC/Ti molar ratio to 20 caused marked increase of [Ci＊]/[Ti]. The number of active centers that produce atactic and medium-isotactic PP chains was less influenced by DEAC in the range of DEAC/Ti = 0-10, but increased when the DEAC/Ti molar ratio was further raised to 20. The propagation rate constant of Ci＊ （k^i） was evidently increased when DEAC/Ti molar ratio was raised from 0 to 5, but further increase in DEAC/Ti ratio caused gradual decrease in kpi. The complicated effect of DEAC on the polymerization kinetics, catalysis behaviors and polymer structure can be reasonably explained by adsorption of DEAC on the central metal of the active centers or on Mg atoms adjacent to the central metal展开更多
CdS nanowires-nitrogen doped graphene （CdS NWs-NGR） nanocomposites have been fabricated by an electrostatic self-assembly strategy followed by a hydrothermal reduction. The CdS NWs-NGR exhibits higher photoactivity ...CdS nanowires-nitrogen doped graphene （CdS NWs-NGR） nanocomposites have been fabricated by an electrostatic self-assembly strategy followed by a hydrothermal reduction. The CdS NWs-NGR exhibits higher photoactivity for selective reduction of aromatic nitro organics in water under visible light irradiation than blank CdS nanowires （CdS NWs） and CdS nanowires-reduced graphene oxide （CdS NWs-RGO） nanocomposites. The enhanced photoactivity of CdS NWs-NGR can be attributed to the improved electronic conductivity due to the introduc- tion of nitrogen atoms, which thus enhances the separation and transfer of charge carriers photogenerated from CdS NWs. Our work could provide a facile method to synthesize NGR based one-dimensional （1D） semiconductor composites for selective organic transformations, and broaden the potential applications for NGR as a cocatalyst.展开更多
In this study,a human-chair model was developed as the basis for a wearable-chair design.A prototype chair,HUST-EC,based on the model was fabricated and evaluated.Employing the optimization under the golden divisional...In this study,a human-chair model was developed as the basis for a wearable-chair design.A prototype chair,HUST-EC,based on the model was fabricated and evaluated.Employing the optimization under the golden divisional method,an optimized simulation of the operating mode with the lowest chair height was implemented.A novel multi-link support structure has been established with parameters optimized using Matlab software.The stress analysis of the solid models was conducted to ensure the adequate support from the designed chair for the user.Ten subjects participated in the evaluation experiment,who performed both static tasks and dynamic tasks.The experimental results consisted of subjective evaluation and objective evaluation.The experimental data demonstrate that(1)the HUST-EC can effectively reduce the activation level of related muscles at a variety of tasks;(2)the plantar pressure was reduced by 54%–67%;(3)the angle between the upper body and the vertical axis was reduced by 59%–77%;(4)the subjective scores for chair comfortability,portability,and stability were all higher than 7.The results further revealed that the designed chair can reduce the musculoskeletal burden and may improve work efficiency.展开更多
The concept of combining metallic honeycomb with folded thin metallic sheets （corrugation） to construct a novel core type for lightweight sandwich structures is proposed. The honeycomb-corrugation hybrid core is man...The concept of combining metallic honeycomb with folded thin metallic sheets （corrugation） to construct a novel core type for lightweight sandwich structures is proposed. The honeycomb-corrugation hybrid core is manufactured by filling the interstices of aluminum corrugations with precision-cut trapezoidal aluminum honeycomb blocks, bonded together using epoxy glue. The performance of such hybrid-cored sandwich panels subjected to out-of-plane compression, transverse shear, and three-point bending is investigated, both experimentally and numerically. The strength and energy absorption of the sandwich are dramatically enhanced, compared to those of a sandwich with either empty corrugation or honeycomb core. The enhancement is induced by the beneficial interaction effects of honeycomb blocks and folded panels on improved buckling resistance as well as altered crushing modes at large plastic deformation. The present approach provides an effective method to further improve the mechanical properties of conventional honeycomb-cored sandwich constructions with low relative densities.展开更多
Cemented paste backill(CPB)is a susta inable mining technology that is widely used in mines and helps to improve the mine environment.To investigate the relationship between aggregate grading and different affecting f...Cemented paste backill(CPB)is a susta inable mining technology that is widely used in mines and helps to improve the mine environment.To investigate the relationship between aggregate grading and different affecting factors and the uniaxial compressive strength(UCS)of the cemented paste backill(CPB),Talbol gradation theory and neural networks is used to evaluate aggregate gradation to determine the optimum aggregate ratio.The mixed aggregate ratio with the least amount of cement(waste stone content river sand content=7:3)is obtained by using Talbol grading theory and pile compactness function and combined with experiments.In addition,the response surface method is used to design strength speaific ratio experiments.The UCS prediction model which ues the ISTM and considers the aggregates gradation have high accuracy.The root mean square error(RMSE)of the prediction results is 0.0914,the coefficient of determination(R^(2))is 0.9973 and the variance account for(VAF)is 99.73.Compared with back propagation neural network(BP-ANN),extreme lea ming machine(ELM)and madal basis function neural network(RBF ANN),LSTM can efectively characterize the nonlinear relationship between UCS and individual affecting factors and predict UCS with high accuracy.The sensitivity analysis of different affecting factors on UCS shows that all 4 factors have significant effect on UCS and sensitivity is in the following ranking:cement content(0.9264)>slurry concentration(0.9179)>aggregate gradation(waste rodk content)(0.9031)>curing time(09031).展开更多
Black carbon(BC)aerosol can lead to adverse health effects and drive climate change;therefore,the characteristic research and identification of BC sources are essential for lowering emissions.In this study,equivalent ...Black carbon(BC)aerosol can lead to adverse health effects and drive climate change;therefore,the characteristic research and identification of BC sources are essential for lowering emissions.In this study,equivalent black carbon(eBC)measurement was performed using a seven-wavelength Aethalometer(AE33)at an urban site in a typical industrial city(Zibo)of Northern China for the first time.The monitoring was performed from February 2021 to January 2022.The mass absorption cross-section(MAC)of AE33 was optimised using the online elemental carbon(EC)data,and eBC was corrected using the MAC.The corrected annual BC concentration was 1.72±1.18μg/m^(3).The diurnal variation of BC depicted a bimodal distribution.Furthermore,the BC concentration on weekends was 18%lower than on weekdays.The diurnal variation and weekend effect reflect the critical contributions of traffic emission to BC concentration.The source apportionment of BC was calculated by a constraining Aethalometer model,which restricted theÅngstrom exponent using the online potassium ions.The results revealed that BC was not significantly affected by biomass burning(BC_(bb))in Zibo.The relative contribution of BC_(bb)was higher in winter than in other seasons.The daily morning peak of BC was primarily influenced by traffic sources,whereas the contribution of biomass burning increased after 17:00 in the evening peak.Our findings suggest that it is more important to control fossil fuel sources for BC emission reduction in Zibo,while it is necessary to strengthen the control of biomass combustion sources in winter.展开更多
Perfluoroalkyl substances(PFASs)are typical persistent organic pollutants,and their removal is urgently required but challenging.Photocatalysis has shown potential in PFASs degradation due to the redox capabilities of...Perfluoroalkyl substances(PFASs)are typical persistent organic pollutants,and their removal is urgently required but challenging.Photocatalysis has shown potential in PFASs degradation due to the redox capabilities of photoinduced charge carriers in photocatalysts.Herein,hexagonal ZnIn_(2)S_(4)(ZIS)nanosheets were synthesized by a one-pot oil bath method and were well characterized by a series of techniques.In the degradation of sodium p-perfluorous nonenoxybenzenesulfonate(OBS),one kind of representative PFASs,the assynthesized ZIS showed activity superior to P25 TiO_(2) under both simulated sunlight and visible-light irradiation.The good photocatalytic performance was attributed to the enhanced light absorption and facilitated charge separation.The pH conditions were found crucial in the photocatalytic process by influencing the OBS adsorption on the ZIS surface.Photogenerated e−and h+were the main active species involved in OBS degradation in the ZIS system.This work confirmed the feasibility and could provide mechanistic insights into the degradation and defluorination of PFASs by visible-light photocatalysis.展开更多
Dimensionality has great influence on the photo/electro-catalysts properties of covalent organic frameworks(COFs) because of the different electronic and porous structures.However,very rare attention has been paid on ...Dimensionality has great influence on the photo/electro-catalysts properties of covalent organic frameworks(COFs) because of the different electronic and porous structures.However,very rare attention has been paid on the dimensionality and function correlations of COF materials.In the present work,one new two-dimensional phthalocyanine COF,namely 2D-NiPc-COF,and one new three-dimensional phthalocyanine COF,namely 3D-NiPc-COF,were fabricated according to the imide reaction between tetraanhydrides of 2,3,9,10,16,17,23,24-octacarboxyphthalocyaninato nickel(Ⅱ) with [2,2-bipyridine]-5,5-diamine and tetrakis(4-aminophenyl) methane,respectively.The crystalline structures of both COFs are verified by the powder X-ray diffraction analysis,computational simulation,and high resolution transmission electron microscopy measurement.Notably,3D-NiPc-COF with dispersed conjugated modules has high utilization efficiency of NiPc electroactive sites of 26.8%,almost two times higher than the in-plane stacking2D-NiPc-COF measured by electrochemical measurement,in turn resulting in its superior electrocatalytic performance with high CO_(2)-to-CO Faradaic efficiency over 90% in a wide potential window,a large partial CO current density of-13.97 mA/cm^(2) at-0.9 V(vs.reversible hydrogen electrode) to 2D-NiPc-COF.Moreover,3D-NiPc-COF has higher turnover number and turnover frequency of 5741.6 and 0.18 s^(-1) at-0.8 V during 8 h lasting measurement.The present work provides an example for the investigation on the correlation between dimensionality and electrochemical properties of 2D and 3D phthalocyanine COFs.展开更多
Photocatalytic water splitting is a promising way to produce H_(2),a green and clean energy source.However,efficient H_(2) production typically relies on the addition of electron donors,such as alcohols and acids,whic...Photocatalytic water splitting is a promising way to produce H_(2),a green and clean energy source.However,efficient H_(2) production typically relies on the addition of electron donors,such as alcohols and acids,which are neither environmentally friendly nor cost-effective.Recently,we have witnessed a surge of studies in coupling photocatalytic H_(2) evolution with organic pollutant oxidation,which significantly promotes charge separation and improves the overall photocatalytic efficiency.It is thus an opportune time to critically assess the recent literature concerning dual-functional photocatalytic systems and provide perspectives for its future development.In this minireview,we begin with the working principles and requirements for synergistic photocatalytic systems.We then summarize and critically discuss the recent advances in photocatalytic H_(2) production and the degradation of various organic pollutants,including antibiotics,dyes,and phenols.Finally,we discuss the current challenges and suggest future directions for this field.展开更多
Brucellosis,a zoonotic disease caused by Brucella infection,poses a major threat to both global health and livestock productivity.Although reproductive impairment is well established,the molecular mechanisms driving t...Brucellosis,a zoonotic disease caused by Brucella infection,poses a major threat to both global health and livestock productivity.Although reproductive impairment is well established,the molecular mechanisms driving testicular immunopathology remain poorly understood.In this study,single-cell RNA sequencing was used to delineate transcriptional changes in goat testicular tissues under physiological and Brucella-infected conditions,revealing dynamic immunological remodeling of the testicular microenvironment.Infection induced marked shifts in T cell and macrophage phenotypes,with T cells exhibiting pronounced hyperactivation linked to CD45-mediated signaling cascades.Thioredoxin-interacting protein(TXNIP),a gene strongly up-regulated in response to infection,emerged as a potential immunotherapeutic target.Intercellular communication networks were significantly disrupted in infected testes,with CD39-and JAM-dependent signaling pathways implicated in the erosion of immune privilege.Regulon analysis further identified GATA3,IRF5,SEMA4A,and HCLS1 as transcriptional regulators associated with T cells and macrophages in infected testes.These findings provide novel insights into the molecular mechanisms driving testicular immunopathology during Brucella infection and highlight candidate targets for immunomodulatory intervention in disease control and livestock reproductive health.展开更多
Covalent organic frameworks(COFs)based photocatalysts utilizing infrared light remains unexplored due to the limitation of electronic absorption.Herein,two novel two-dimensional(2D)polyimide-linked phthalocyanine COFs...Covalent organic frameworks(COFs)based photocatalysts utilizing infrared light remains unexplored due to the limitation of electronic absorption.Herein,two novel two-dimensional(2D)polyimide-linked phthalocyanine COFs,namely MPc-DPA-COFs(M=Zn/Cu),were prepared from the imidization reaction of metal tetraanhydrides of 2,3,9,10,16,17,23,24-octacarboxyphthalocyaninato(M(TAPc))with 9,10-diphenyl anthracene(DPA).Both COFs possess highly crystalline eclipsed AA stacking structure with neighboring layer distance of 0.33 nm on the basis of powder X-ray diffraction analysis and high-resolution transmission electron microscopy.Effective π–π interaction between phthalocyanine chromophores in neighboring layers of 2D COFs leads to significant bathochromic-shift of narrow Q band from 697 nm for M(TAPc)to the infrared light absorption range of 760–1000 nm for MPc-DPA-COFs according to solid UV-vis diffuse reflectance spectra.This endows them in particular ZnPc-DPA-COF with excellent reactive oxygen species of•O_(2)^(–)and 1O_(2) generation activity under infrared light radiation(λ>760 nm)based on the electron spin resonance spectroscopy measurement,in turn resulting in the excellent photocatalytic capacity towards oxidation of sulfides under infrared light radiation.Corresponding quenching experiments reveal the contribution of both•O_(2)^(–)and 1O_(2) to the oxidation of sulfides,but the former•O_(2)^(–)species plays a leading role in this photocatalytic process.The present result not only provides a new efficient infrared light photocatalyst but also unveils the good potentials of phthalocyanine-based COFs in photocatalysis.展开更多
基金supported by Opening funding of National Key Laboratory of Aerospace Liquid Propulsion(HTKJ2024KL011004)Aeronautical Science Fund of China(ASFC-20240042070001)+2 种基金Opening funding of State Key Laboratory of Metal Forming Technology and Heavy Equipment(B2408100.W05)National Key R&D Program of China(2022YFB4601804)National Natural Science Foundation of China(52250287,52275375).
文摘Incorporating ceramic particles into metal matrices is a proven strategy for boosting mechanical properties and wear resistance.The reinforcement potential of tungsten carbide(WC)particles in 316L stainless steel is revealed,utilizing selective laser melting(SLM)to fabricate composites with 5 and 10 vol.%WC.The WC incorporation markedly alters the composite’s microstructure and mechanical attributes.Notably,5 vol.%WC-316L composite exhibits a refined submicron cellular structure,averaging 0.67μm in grain size.Elemental diffusion at WC-316L interface formed a 0.8μm gradient transition layer enriched with M_(2)C carbides(Fe,Cr,W),ensuring robust metallurgical bonding.Compared with unreinforced 316L,5%WC composite exhibits a 70%increase in tensile strength,reaching 1012.6 MPa,and a 25.3%rise in hardness,while maintaining acceptable ductility.10%WC composite achieves a 70.8%hardness enhancement,albeit with reduced elongation.Friction coefficient is reduced by up to 17.3%,and the wear mechanism shifts from adhesive to abrasive,significantly improving wear resistance.
基金supported by the National Research Program for Key Issues in Air Pollution Control in China(No.DQGG202137)the National Natural Science Foundation of China(No.42277429)。
文摘The COVID-19 lockdown was a typical example of extreme emission reduction,providing an opportunity to study the impact of lockdown measures on air pollution.Particle number concentrations(PNC)originate from direct emissions or through new particle formation events.However,their variations during the lockdown period are under investigation.This study focuses on Luohe,a city on the southern edge of the North China Plain,analyzing the changes in PNC and its sources before,during,and after the COVID-19 lockdown.From March 25^(th)to May 31^(st),2022,real-time PNC measurements were conducted using a Scanning Mobility Particle Sizer for particle size.Results showed an 11.2%decrease in PNC during the lockdown compared to pre-lockdown and a 3.6%decrease compared to post-lockdown,indicating reduced local emissions and weakened regional transportation during the lockdown.Positive Matrix Factorization analysis identified six sources contributing to the total PNC,including photochemical nucleation,aged photochemical nucleation,gasoline vehicle emissions,diesel vehicle emissions,coal and biomass combustion,and secondary aerosols.The significant changes in source emissions indicate a substantially reduced traffic volume after the implementation of lockdown measures(2644.8#/cm^(3),2202.2#/cm^(3),2792.7#/cm^(3)).Concurrently,photochemical nucleation(310.1#/cm^(3),306.3#/cm^(3),393.1#/cm^(3))and photochemical nucleation aging(592.8#/cm^(3),744.1#/cm^(3),810.7#/cm^(3))exhibited increasing trends,while coal/biomass combustion(1656.6#/cm^(3),1586.2#/cm^(3),980.0#/cm^(3))and secondary sources(999.4#/cm^(3),791.1#/cm^(3),804.1#/cm^(3))showed decreasing trends.In summary,the contributions of traffic emissions to PNC highlight the potential for targeted traffic management strategies to improve urban air quality.
基金supported by the Natural Science Foundation(NSF)of China(Nos.22205015,22175020,and 22235001)the National Postdoctoral Program for Innovative Talents(No.BX20220032)+2 种基金the China Postdoctoral Science Foundation Funded Project(No.2022BG013)the Fundamental Research Funds for the Central Universities(Nos.00007709,00007770,and FRFBR-23-02B)University of Science and Technology Beijing is gratefully acknowledged.
文摘In comparison with their 2D and 3D counterparts,1D covalent organic frameworks(COFs)have rarely been investigated due to the synthetic challenge arising from the strict necessary matching in the molecular symmetry between corresponding building blocks and linking units in addition to the unmanageable packing of 1D organic chains once formed.Herein,two novel imide-linked 1D COFs with phthalocyanine building blocks,namely NiPc-CZDM-COF and NiPc-CZDL-COF,were fabricated from the hydrothermal synthesis reaction of 2,3,9,10,16,17,23,24-octacarboxyphthalocyaninato nickel(II)(NiPc(COOH)_(8))with 9H-carbazole-3,6-diamine(CZDM)and 4,4′-(9H-carbazole-3,6-diyl)dianiline(CZDL),respectively.Two COFs have high crystallinity on the basis of powder X-ray diffraction analysis and high-resolution transmission electron microscopy.Due to their high ratio of exposed active centers on the edge sites of porous ribbons,both NiPc-CZDM-COF and NiPc-CZDL-COF electrodes display high utilization efficiency of NiPc electroactive sites of 8.0%and 7.5% according to the electrochemical measurement,resulting in their excellent capacity toward electrocatalytic nitrate reduction with the nitrate-to-NH3 Faradaic efficiency of nearly 100%.In particular,NiPc-CZDM-COF electrode exhibits superior electrocatalytic performance with high NH_(3) partial current density of−246 mA/cm^(2),ammonia yield rate of 19.5 mg cm^(−2) h^(−1),and turnover frequency of 5.8 s^(−1) at−1.2 V in an H-type cell associated with its higher conductivity.This work reveals the good potential of 1D porous crystalline materials in electrocatalysis.
基金the support from the National Science Foundation of China(22471226,22272142)the 111 Project(B16029)。
文摘The performance of lithium-sulfur batteries(LSBs)is severely limited by a detrimental negative feedback loop:sluggish polysulfide conversion kinetics lead to Li_(2)S accumulation,which further hinders lithiumion transport and exacerbates capacity decay.To address this,we propose a positive feedback strategy that simultaneously enhances lithium polysulfides(LiPSs)conversion and lithium-ion diffusion through a rationally designed separator.By modifying the separator with phosphorus-doped two-dimensional hollow holey carbon nanosheets(Hollow HCNS),we establish an interconnected network where rapid LiPSs confinement and conversion within the hollow cavities promote efficient lithium-ion transport,while the improved ion flux further accelerates reaction kinetics.This mutual reinforcement mechanism ensures stable cycling by suppressing the shuttle effect and promoting uniform Li_(2)S deposition,as verified by in situ spectroscopic and electrochemical analysis.The resulting LSBs exhibit high-rate capability,ultralow capacity decay,and exceptional stability under high sulfur loading.This work presents a general approach to overcoming the persistent negative feedback problem in high-energy battery systems by synergistically optimizing catalytic conversion and ionic transport.
基金supported by the National Natural Science Foundation of China(U2032131)the Key R&D Program of Shaanxi Province(2021GY-118)the Shanxi-Zheda Institute of Advanced Materials and Chemical Engineering(2022SX-TD012 and 2021SXTD012)。
文摘LiNi_(0.8)Co_(0.1)Mn_(0.1)O_(2)(NCM811)layered oxides have been regarded as promising alternative cathodes for the next generation of high-energy lithium ion batteries(LIBs)due to high discharge capacities and energy densities at high operation voltage.However,the capacity fading under high operation voltage still restricts the practical application.Herein,the capacity degradation mechanism of NCM811 at atomic-scale is studied in detail under various cut-off voltages using aberration-corrected scanning transmission electron microscopy(STEM).It is observed that the crystal structure of NCM811 evolution from a layered structure to a rock-salt phase is directly accompanied by serious intergranular cracks under 4.9 V,which is distinguished from the generally accepted structure evolution of layered,disordered layered,defect rock salt and rock salt phases,also observed under 4.3 and 4.7 V.The electron energy loss spectroscopy analysis also confirms the reduction of Ni and Co from the surface to the bulk,not the previously reported only Li/Ni interlayer mixing.The degradation mechanism of NCM811 at a high cut-off voltage of4.9 V is attributed to the formation of intergranular cracks induced by defects,the direct formation of the rock salt phase,and the accompanied reduction of Ni^(2+)and Co^(2+)phases from the surface to the bulk.
基金supported by the National Natural Science Foundation of China (No. 21074108)the Major State Basic Research Programs (No. 2011CB606001)
文摘In this article, the effect of diethylaluminum chloride （DEAC） in propylene polymerization with MgC12-supported Ziegler-Natta catalyst was studied. Addition of DEAC in the catalyst system caused evident change in catalytic activity and polymer chain structure. The activity decrease in raising DEAC/Ti molar ratio from 0 to 2 is a result of depressed production of isotactic polypropylene chains. The number of active centers in fractions of each polymer sample was determined by quenching the polymerization with 2-thiophenecarbonyl chloride and fractionating the polymer into isotactic, medium- isotactic and atactic fractions. The number of active centers in isotactic fraction （[Ci＊]/[Ti]） was lowered by increasing DEAC/Ti molar ratio to 2, but further increasing the DEAC/Ti molar ratio to 20 caused marked increase of [Ci＊]/[Ti]. The number of active centers that produce atactic and medium-isotactic PP chains was less influenced by DEAC in the range of DEAC/Ti = 0-10, but increased when the DEAC/Ti molar ratio was further raised to 20. The propagation rate constant of Ci＊ （k^i） was evidently increased when DEAC/Ti molar ratio was raised from 0 to 5, but further increase in DEAC/Ti ratio caused gradual decrease in kpi. The complicated effect of DEAC on the polymerization kinetics, catalysis behaviors and polymer structure can be reasonably explained by adsorption of DEAC on the central metal of the active centers or on Mg atoms adjacent to the central metal
基金supported by the National Natural Science Foundation of China(NSFC)(20903022,20903023,21173045)the Award Program for Minjiang Scholar Professorship+2 种基金the Science and Technology Development of Foundation of Fuzhou University(2009-XQ-10)the Open Fund of Photocatalysis of Fuzhou University(0380038004)the Program for Returned High-Level Overseas Chinese Scholars of Fujian Province
文摘CdS nanowires-nitrogen doped graphene （CdS NWs-NGR） nanocomposites have been fabricated by an electrostatic self-assembly strategy followed by a hydrothermal reduction. The CdS NWs-NGR exhibits higher photoactivity for selective reduction of aromatic nitro organics in water under visible light irradiation than blank CdS nanowires （CdS NWs） and CdS nanowires-reduced graphene oxide （CdS NWs-RGO） nanocomposites. The enhanced photoactivity of CdS NWs-NGR can be attributed to the improved electronic conductivity due to the introduc- tion of nitrogen atoms, which thus enhances the separation and transfer of charge carriers photogenerated from CdS NWs. Our work could provide a facile method to synthesize NGR based one-dimensional （1D） semiconductor composites for selective organic transformations, and broaden the potential applications for NGR as a cocatalyst.
基金This work is partially supported by the National Natural Science Foundation of China(NSFC)under grant numbers 51705163the Fundamental Research Funds for the Central Universities(HUST)under grand numbers 2019kfyXKJC003 and 2019JYCXJJ022.
文摘In this study,a human-chair model was developed as the basis for a wearable-chair design.A prototype chair,HUST-EC,based on the model was fabricated and evaluated.Employing the optimization under the golden divisional method,an optimized simulation of the operating mode with the lowest chair height was implemented.A novel multi-link support structure has been established with parameters optimized using Matlab software.The stress analysis of the solid models was conducted to ensure the adequate support from the designed chair for the user.Ten subjects participated in the evaluation experiment,who performed both static tasks and dynamic tasks.The experimental results consisted of subjective evaluation and objective evaluation.The experimental data demonstrate that(1)the HUST-EC can effectively reduce the activation level of related muscles at a variety of tasks;(2)the plantar pressure was reduced by 54%–67%;(3)the angle between the upper body and the vertical axis was reduced by 59%–77%;(4)the subjective scores for chair comfortability,portability,and stability were all higher than 7.The results further revealed that the designed chair can reduce the musculoskeletal burden and may improve work efficiency.
基金supported by the National Natural Science Foundation of China(11472208)the National 111 Project of China(B06024)
文摘The concept of combining metallic honeycomb with folded thin metallic sheets （corrugation） to construct a novel core type for lightweight sandwich structures is proposed. The honeycomb-corrugation hybrid core is manufactured by filling the interstices of aluminum corrugations with precision-cut trapezoidal aluminum honeycomb blocks, bonded together using epoxy glue. The performance of such hybrid-cored sandwich panels subjected to out-of-plane compression, transverse shear, and three-point bending is investigated, both experimentally and numerically. The strength and energy absorption of the sandwich are dramatically enhanced, compared to those of a sandwich with either empty corrugation or honeycomb core. The enhancement is induced by the beneficial interaction effects of honeycomb blocks and folded panels on improved buckling resistance as well as altered crushing modes at large plastic deformation. The present approach provides an effective method to further improve the mechanical properties of conventional honeycomb-cored sandwich constructions with low relative densities.
基金This study was supported by the National Key Research and Development Program of China(2018YFC 1900603,2018YFC0604604).
文摘Cemented paste backill(CPB)is a susta inable mining technology that is widely used in mines and helps to improve the mine environment.To investigate the relationship between aggregate grading and different affecting factors and the uniaxial compressive strength(UCS)of the cemented paste backill(CPB),Talbol gradation theory and neural networks is used to evaluate aggregate gradation to determine the optimum aggregate ratio.The mixed aggregate ratio with the least amount of cement(waste stone content river sand content=7:3)is obtained by using Talbol grading theory and pile compactness function and combined with experiments.In addition,the response surface method is used to design strength speaific ratio experiments.The UCS prediction model which ues the ISTM and considers the aggregates gradation have high accuracy.The root mean square error(RMSE)of the prediction results is 0.0914,the coefficient of determination(R^(2))is 0.9973 and the variance account for(VAF)is 99.73.Compared with back propagation neural network(BP-ANN),extreme lea ming machine(ELM)and madal basis function neural network(RBF ANN),LSTM can efectively characterize the nonlinear relationship between UCS and individual affecting factors and predict UCS with high accuracy.The sensitivity analysis of different affecting factors on UCS shows that all 4 factors have significant effect on UCS and sensitivity is in the following ranking:cement content(0.9264)>slurry concentration(0.9179)>aggregate gradation(waste rodk content)(0.9031)>curing time(09031).
基金supported by the National Key Research and Development Program of China(Nos.2017YFC0212501 and 2017YFC0212503).
文摘Black carbon(BC)aerosol can lead to adverse health effects and drive climate change;therefore,the characteristic research and identification of BC sources are essential for lowering emissions.In this study,equivalent black carbon(eBC)measurement was performed using a seven-wavelength Aethalometer(AE33)at an urban site in a typical industrial city(Zibo)of Northern China for the first time.The monitoring was performed from February 2021 to January 2022.The mass absorption cross-section(MAC)of AE33 was optimised using the online elemental carbon(EC)data,and eBC was corrected using the MAC.The corrected annual BC concentration was 1.72±1.18μg/m^(3).The diurnal variation of BC depicted a bimodal distribution.Furthermore,the BC concentration on weekends was 18%lower than on weekdays.The diurnal variation and weekend effect reflect the critical contributions of traffic emission to BC concentration.The source apportionment of BC was calculated by a constraining Aethalometer model,which restricted theÅngstrom exponent using the online potassium ions.The results revealed that BC was not significantly affected by biomass burning(BC_(bb))in Zibo.The relative contribution of BC_(bb)was higher in winter than in other seasons.The daily morning peak of BC was primarily influenced by traffic sources,whereas the contribution of biomass burning increased after 17:00 in the evening peak.Our findings suggest that it is more important to control fossil fuel sources for BC emission reduction in Zibo,while it is necessary to strengthen the control of biomass combustion sources in winter.
基金supported by the National Natural Science Foundation of China (Nos.22206113 and 22376124)the Outstanding Youth Science Fund (Overseas)of Shandong Provincial Natural Science Foundation (No.2022HWYQ-015)+2 种基金the Taishan Scholars Project Special Fund (No.tsqn202211039)the Guangdong Basic and Applied Basic Research Foundation (No.2021A1515111137)Qilu Youth Talent Program of Shandong University (No.61440082163171).
文摘Perfluoroalkyl substances(PFASs)are typical persistent organic pollutants,and their removal is urgently required but challenging.Photocatalysis has shown potential in PFASs degradation due to the redox capabilities of photoinduced charge carriers in photocatalysts.Herein,hexagonal ZnIn_(2)S_(4)(ZIS)nanosheets were synthesized by a one-pot oil bath method and were well characterized by a series of techniques.In the degradation of sodium p-perfluorous nonenoxybenzenesulfonate(OBS),one kind of representative PFASs,the assynthesized ZIS showed activity superior to P25 TiO_(2) under both simulated sunlight and visible-light irradiation.The good photocatalytic performance was attributed to the enhanced light absorption and facilitated charge separation.The pH conditions were found crucial in the photocatalytic process by influencing the OBS adsorption on the ZIS surface.Photogenerated e−and h+were the main active species involved in OBS degradation in the ZIS system.This work confirmed the feasibility and could provide mechanistic insights into the degradation and defluorination of PFASs by visible-light photocatalysis.
基金Financial support from the Natural Science Foundation(NSF) of China(Nos.22205015,22175020,and 22235001)the National Postdoctoral Program for Innovative Talents(No.BX20220032)+1 种基金the China Postdoctoral Science Foundation Funded Project(No.2022BG013)the Fundamental Research Funds for the Central Universities(Nos.00007709 and 00007770)。
文摘Dimensionality has great influence on the photo/electro-catalysts properties of covalent organic frameworks(COFs) because of the different electronic and porous structures.However,very rare attention has been paid on the dimensionality and function correlations of COF materials.In the present work,one new two-dimensional phthalocyanine COF,namely 2D-NiPc-COF,and one new three-dimensional phthalocyanine COF,namely 3D-NiPc-COF,were fabricated according to the imide reaction between tetraanhydrides of 2,3,9,10,16,17,23,24-octacarboxyphthalocyaninato nickel(Ⅱ) with [2,2-bipyridine]-5,5-diamine and tetrakis(4-aminophenyl) methane,respectively.The crystalline structures of both COFs are verified by the powder X-ray diffraction analysis,computational simulation,and high resolution transmission electron microscopy measurement.Notably,3D-NiPc-COF with dispersed conjugated modules has high utilization efficiency of NiPc electroactive sites of 26.8%,almost two times higher than the in-plane stacking2D-NiPc-COF measured by electrochemical measurement,in turn resulting in its superior electrocatalytic performance with high CO_(2)-to-CO Faradaic efficiency over 90% in a wide potential window,a large partial CO current density of-13.97 mA/cm^(2) at-0.9 V(vs.reversible hydrogen electrode) to 2D-NiPc-COF.Moreover,3D-NiPc-COF has higher turnover number and turnover frequency of 5741.6 and 0.18 s^(-1) at-0.8 V during 8 h lasting measurement.The present work provides an example for the investigation on the correlation between dimensionality and electrochemical properties of 2D and 3D phthalocyanine COFs.
基金supported by the National Natural Science Foundation of China(Nos.22206113 and 22376124)the Outstanding Youth Science Fund(Overseas)of Shandong Provincial Natural Science Foundation(No.2022HWYQ-015)+4 种基金the Taishan Scholars Project Special Fund(No.tsqn202211039)the Guangdong Basic and Applied Basic Research Foundation(No.2021A1515111137)Qilu Youth Talent Program of Shandong University(No.61440082163171)the Natural Sciences and Engineering Research Council of Canadale Fonds de recherche du Quebec-Nature et technologies.
文摘Photocatalytic water splitting is a promising way to produce H_(2),a green and clean energy source.However,efficient H_(2) production typically relies on the addition of electron donors,such as alcohols and acids,which are neither environmentally friendly nor cost-effective.Recently,we have witnessed a surge of studies in coupling photocatalytic H_(2) evolution with organic pollutant oxidation,which significantly promotes charge separation and improves the overall photocatalytic efficiency.It is thus an opportune time to critically assess the recent literature concerning dual-functional photocatalytic systems and provide perspectives for its future development.In this minireview,we begin with the working principles and requirements for synergistic photocatalytic systems.We then summarize and critically discuss the recent advances in photocatalytic H_(2) production and the degradation of various organic pollutants,including antibiotics,dyes,and phenols.Finally,we discuss the current challenges and suggest future directions for this field.
基金supported by the National Key Research and Development Program of China (2023YFF1000904,2022YFD1302201)National Natural Science Foundation of China(32372970, U24A20438)+2 种基金Key Technologies Demonstration of Animal Husbandry in Shaanxi Province (2025NYGG005, 2024NYGG005)Inner Mongolia Autonomous Region Open Competition Projects(2022JBGS0025)Open Fund Project of the National Key Laboratory of Veterinary Public Health and Safety (2025SKLVPHS08)。
文摘Brucellosis,a zoonotic disease caused by Brucella infection,poses a major threat to both global health and livestock productivity.Although reproductive impairment is well established,the molecular mechanisms driving testicular immunopathology remain poorly understood.In this study,single-cell RNA sequencing was used to delineate transcriptional changes in goat testicular tissues under physiological and Brucella-infected conditions,revealing dynamic immunological remodeling of the testicular microenvironment.Infection induced marked shifts in T cell and macrophage phenotypes,with T cells exhibiting pronounced hyperactivation linked to CD45-mediated signaling cascades.Thioredoxin-interacting protein(TXNIP),a gene strongly up-regulated in response to infection,emerged as a potential immunotherapeutic target.Intercellular communication networks were significantly disrupted in infected testes,with CD39-and JAM-dependent signaling pathways implicated in the erosion of immune privilege.Regulon analysis further identified GATA3,IRF5,SEMA4A,and HCLS1 as transcriptional regulators associated with T cells and macrophages in infected testes.These findings provide novel insights into the molecular mechanisms driving testicular immunopathology during Brucella infection and highlight candidate targets for immunomodulatory intervention in disease control and livestock reproductive health.
文摘Covalent organic frameworks(COFs)based photocatalysts utilizing infrared light remains unexplored due to the limitation of electronic absorption.Herein,two novel two-dimensional(2D)polyimide-linked phthalocyanine COFs,namely MPc-DPA-COFs(M=Zn/Cu),were prepared from the imidization reaction of metal tetraanhydrides of 2,3,9,10,16,17,23,24-octacarboxyphthalocyaninato(M(TAPc))with 9,10-diphenyl anthracene(DPA).Both COFs possess highly crystalline eclipsed AA stacking structure with neighboring layer distance of 0.33 nm on the basis of powder X-ray diffraction analysis and high-resolution transmission electron microscopy.Effective π–π interaction between phthalocyanine chromophores in neighboring layers of 2D COFs leads to significant bathochromic-shift of narrow Q band from 697 nm for M(TAPc)to the infrared light absorption range of 760–1000 nm for MPc-DPA-COFs according to solid UV-vis diffuse reflectance spectra.This endows them in particular ZnPc-DPA-COF with excellent reactive oxygen species of•O_(2)^(–)and 1O_(2) generation activity under infrared light radiation(λ>760 nm)based on the electron spin resonance spectroscopy measurement,in turn resulting in the excellent photocatalytic capacity towards oxidation of sulfides under infrared light radiation.Corresponding quenching experiments reveal the contribution of both•O_(2)^(–)and 1O_(2) to the oxidation of sulfides,but the former•O_(2)^(–)species plays a leading role in this photocatalytic process.The present result not only provides a new efficient infrared light photocatalyst but also unveils the good potentials of phthalocyanine-based COFs in photocatalysis.
