In this study,a novel class of niobium(Nb) doped titanate nanoflakes(TNFs) are fabricated through a onestep hydrothermal method.Nb doping affects the curving of titanate nanosheet,leading to the formation of nanoflake...In this study,a novel class of niobium(Nb) doped titanate nanoflakes(TNFs) are fabricated through a onestep hydrothermal method.Nb doping affects the curving of titanate nanosheet,leading to the formation of nanoflake structure.In addition,Nb5+ filled in the interlayers of [TiO6] alters the light adsorption property of pristine titanate.The band gap of Nb-TNFs is narrowed to 2.85 eV,while neat titanate nano tubes(TNTs) is 3.4 eV.The enhanced visible light adsorption significantly enhances the visible-lightdriven activity of Nb-TNFs for ibuprofen(IBP) degradation.The pseudo-first order kinetics constant for Nb-TNFs is calculated to be 1.04 h^-1,while no obvious removal is observed for TNTs.Photo-generated holes(h^+) and hydroxyl radicals(·OH) are responsible for IBP degradation.The photocatalytic activity of Nb-TNFs depends on pH condition,and the optimal pH value is found to be 5.In addition,Nb-TNFs exhibited superior photo-stability during the reuse cycles.The results demonstrated Nb-TNFs are very promising in photocatalytic water purification.展开更多
The droplet formation dynamics of a Newtonian liquid in a drop-on-demand (DOD) inkjet process is numerically investigated by using a volume-of-fluid (VOF) method. We focus on the nozzle geometry, wettability of the in...The droplet formation dynamics of a Newtonian liquid in a drop-on-demand (DOD) inkjet process is numerically investigated by using a volume-of-fluid (VOF) method. We focus on the nozzle geometry, wettability of the interior surface, and the fluid properties to achieve the stable droplet formation with higher velocity. It is found that a nozzle with contracting angle of 45° generates the most stable and fastest single droplet, which is beneficial for the enhanced printing quality and high-throughput printing rate. For this nozzle with the optimal geometry, we systematically change the wettability of the interior surface, i.e., different contact angles. As the contact angle increases, pinch-off time increases and the droplet speed reduces. Finally, fluids with different properties are investigated to identify the printability range.展开更多
Hollow microsphere structure cobalt hydroxide(h-Co(OH)2) was synthesized via an optimized solvothermal-hydrothermal process and applied to activate peroxymonosulfate(PMS) for degradation of a typical pharmaceutically ...Hollow microsphere structure cobalt hydroxide(h-Co(OH)2) was synthesized via an optimized solvothermal-hydrothermal process and applied to activate peroxymonosulfate(PMS) for degradation of a typical pharmaceutically active compound,ibuprofen(IBP).The material characterizations confirmed the presence of the microscale hollow spheres with thin nanosheets shell in h-Co(OH)2,and the crystalline phase was assigned to a-Co(OH)2.h-Co(OH)2 could efficiently activate PMS for radicals production,and 98.6% of IBP was degraded at 10 min.The activation of PMS by h-Co(OH)2 was a pHindependent process,and pH 7 was the optimum condition for the activation-degradation system.Scavenger quenching test indicated that the sulfate radical(SO4^·-) was the primary reactive oxygen species for IBP degradation,which contributed to 75.7%.Fukui index(f^-) based on density functional theory(DFT) calculation predicted the active sites of IBP molecule for SO4^·- attack,and then IBP degradation pathway was proposed by means of intermediates identification and theoretical calculation.The developed hollow Co(OH)2 used to efficiently activate PMS is promising and innovative alternative for organic contaminants removal from water and wastewater.展开更多
Softening behavior of lath martensitic steels is related to the coarsening of laths and dislocation evolution during cyclic deformation.Involving the physical mechanism,we developed a dislocation-based model to study ...Softening behavior of lath martensitic steels is related to the coarsening of laths and dislocation evolution during cyclic deformation.Involving the physical mechanism,we developed a dislocation-based model to study the cyclic plastic response for lath martensitic steels.For a block,we proposed an interfacial dislocation evolution model to physically present the interaction between mobile dislocations in the block and interfacial dislocations by considering the coarsening mechanism of the laths.Moreover,the evolution behavior of backstress caused by dislocation pile up at the block boundary has been considered.Then,a hierarchical model based on the elastic-viscoplastic self-consistent(EVPSC)theory is developed,which can realize the scale transition among representative volume element(RVE),prior austenite grains(PAGs)and blocks.According to the proposed model,the effective mechanical responses including the cyclic hysteretic loop and peak stress at different cycles for lath martensitic steel have been theoretically predicted and investigated.展开更多
Heterostructures are a series of nanomaterials combining different components into a single nanostructure. Au-FeOheterostructures have received considerable attentions because of their superior properties coming from ...Heterostructures are a series of nanomaterials combining different components into a single nanostructure. Au-FeOheterostructures have received considerable attentions because of their superior properties coming from both individual and combinational features of gold and iron oxide nanoparticles. Their intrinsically peculiar magnetic, optical properties, and structure designability greatly enhance and broaden their potential applications in catalysis, assay, multimodal imaging, and synergistic treatment for tumor. In this review, we systematically introduce the preparation methods of Au-FeOheterostructures and their potential applications in the biomedical field, focusing on the unique synergistic effect caused by the combination of gold and iron oxide structures. This review will provide insights into the structure control in adjusting the function of heterogeneous or hybrid material, such as Au-FeOheterostructures, to implement their biomedical applications.展开更多
Lightweight nanocomposites consisting of magnetic and dielectric units aroused intensive interest as potential high performance electromagnetic wave absorbing materials.In this work,we report a facile and efficient me...Lightweight nanocomposites consisting of magnetic and dielectric units aroused intensive interest as potential high performance electromagnetic wave absorbing materials.In this work,we report a facile and efficient method to fabricate(Co,SiO_(2))/PPy composites with tunable electromagnetic properties.The absorbing properties and effective absorbing bandwidth can be regulated by controlling the content of SiO_(2) in composites.The composite shows a maximum reflection loss(RL)of-65.31 d B at 11.12 GHz with a thickness of 3.002 mm when SiO_(2) being 22 wt.%.The effective absorbing bandwidth reaches up to 5.1 GHz(8.91-14.01 GHz),which covers the entire X band(8-12 GHz).The improved impedance matching,high interfacial polarization and complex electromagnetic synergy in the composites are the key factors giving rise to the higher efficient absorption.The PPy aerogel-based nanocomposites with controllable absorption performance,lower density and strong environmental adaptability will become attractive candidates as advanced microwave absorbing materials.展开更多
Listeria monocytogenes(L.monocytogenes)is one of the top five dangerous foodborne pathogens which widely exists in most raw food and has approximately 30%mortality rate in high-risk groups.Food safety caused by foodbo...Listeria monocytogenes(L.monocytogenes)is one of the top five dangerous foodborne pathogens which widely exists in most raw food and has approximately 30%mortality rate in high-risk groups.Food safety caused by foodborne pathogens is still a major problem faced by humans in all world.The conventional analytical methods currently used involve complex bacteriological tests and usually take several days for incubation and analysis.Thus,in order to prevent the spread of disease,the development of a detection method with high speed,high accuracy and sensitivity is urgent and necessary.Herein,we developed an approach for the identification and magnetic capture of L.monocytogenes by using core@shell Fe_(3)O_(4)@silica nanoparticles terminated with hydroxyl or amine groups.Our results show that both amine-and hydroxyl-terminated Fe_(3)O_(4)@silica core@shell nanoparticles functionalized with specific antibodies,present 95.2%±6.2%and 98.6%±0.3%capture efficacies,respectively.However,without conjugating the specific antibodies,the hydroxyl-terminated Fe_(3)O_(4)@silica nanoparticles exhibit 17.6%±1.6%efficacy,while the amine-terminated one remains 93.2%±9.2%capture efficiency ascribed to the high affinity.This study quantitatively uncovers the specific and non-specific recognitions relevant to the molecular-scale physiochemical interactions between the microorganisms and the functionalized particles,and the results from this work can be generalized and extended to other bacterial species by changing antibodies,also have important implications in developing advanced analytic methods.展开更多
As a cross-cutting field between ocean development and multi-robot system(MRS),the underwater multi-robot system(UMRS)has gained increasing attention from researchers and engineers in recent decades.In this paper,we p...As a cross-cutting field between ocean development and multi-robot system(MRS),the underwater multi-robot system(UMRS)has gained increasing attention from researchers and engineers in recent decades.In this paper,we present a comprehensive survey of cooperation issues,one of the key components of UMRS,from the perspective of the emergence of new functions.More specifically,we categorize the cooperation in terms of task-space,motion-space,measurement-space,as well as their combination.Further,we analyze the architecture of UMRS from three aspects,i.e.,the performance of the individual underwater robot,the new functions of underwater robots,and the technical approaches of MRS.To conclude,we have discussed related promising directions for future research.This survey provides valuable insight into the reasonable utilization of UMRS to attain diverse underwater tasks in complex ocean application scenarios.展开更多
Building highly active and stable noble metal single atom(MSA)catalyst onto photocatalyst materials for nitrogen reduction reaction(NRR)and CO2 reduction reaction(CRR)is a key to future renewable energy conversion and...Building highly active and stable noble metal single atom(MSA)catalyst onto photocatalyst materials for nitrogen reduction reaction(NRR)and CO2 reduction reaction(CRR)is a key to future renewable energy conversion and storage technologies.Here we present a design strategy to optimize the stability and electronic property of noble metal single atoms(MSAs,M=Rh,Pd,Ag,Ir,Pt,Au)catalyst supported on g-C3N4 and 2H-MoS2 photocatalysts towards NRR and CRR.Our results indicate that the MSAs tend to be trapped at the anion-vacancy sites of photocatalyst rather than the pristine photocatalyst surface.This anion vacancy can promise the MSAs with an optimized electron-captured ability in the photoexcitation process,thus decreasing the energy barriers of NRR and CRR on MSAs.Especially,it is revealed that the N-vacancy-stabilized Ir SA on g-C3N4 and the S-vacancy-stabilized RhSA on 2H-MoS2 own the lowest energy barrier in NRR.However,for CRR,the HCOOH is the main product on MSAs supported by gC3N4 and 2H-MoS2.The N-vacancy-stabilized PdSA on g-C3N4 and the S-vacancy-stabilized AuSA on 2H-MoS2 show the lowest energy barrier for HCOOH production in CRR.This finding offers an approach to design specific active MSA centres on photocatalysts by the anion vacancy engineering.展开更多
A novel carbon quantum dots modified potassium titanate nanotubes(CQDs/K2 Ti6 O13)composite photocatalyst was synthesized by hydrothermal treatment combined with calcination.X-ray diffraction(XRD)pattern and transmiss...A novel carbon quantum dots modified potassium titanate nanotubes(CQDs/K2 Ti6 O13)composite photocatalyst was synthesized by hydrothermal treatment combined with calcination.X-ray diffraction(XRD)pattern and transmission electron microscopy(TEM)indicated formation of potassium titanate nanotubes and successful deposition of CQDs onto K2 Ti6 O13.The photocatalytic performance of CQDs/K2 Ti6 O13 composite was evaluated by degradation of amoxicillin(AMX)under the irradiation of visible light and lights with the wavelengths of 365,385,420,450,485,520,595 and 630 nm.The results showed that the photocatalytic activity of CQDs/K2 Ti6 O13 hybrid material was greatly enhanced compared with the neat K2 Ti6 O13 calcined at 300℃.The narrowed band gap energy(Eg)and transfer of photo-excited electron by CQDs inhibited the immediate combination of electron-hole pairs,thus promoting photocatalytic activity.Moreover,CQ,Ds/K2 Ti6 O13 exhibited a broad spectrum of photocatalytic ability and it was interesting that the photocatalytic activity decreased with the increase of the irradiation wavelength.Reactive oxygen species(ROS)quenching tests suggested the hole(h^+)and hydroxyl radical(^·OH)played the primary roles in photocatalytic degradation of AMX.Moreover,CQ.Ds/K2 Ti6 O13 showed good reusability for AMX photocatalytic degradation after five successive runs.This study proposed an available method for titanate nanomaterials modification,and the developed novel CQDs/K2 Ti6 O13hyb rid material is p ro mising fo r potential application on antibiotics removal fro m water and wastewater.展开更多
Reductive immobilization of radioactive pertechnetate(99TcO4^-) in simulated groundwater was studied by prepared carboxymethyl cellulose(CMC) and starch stabilized zero valent iron nanoparticles(nZVI),and long-term re...Reductive immobilization of radioactive pertechnetate(99TcO4^-) in simulated groundwater was studied by prepared carboxymethyl cellulose(CMC) and starch stabilized zero valent iron nanoparticles(nZVI),and long-term remobilization of reduced Tc was also evaluated under anoxic and oxic conditions.The stabilized nZVI can effectively reduce soluble 99Tc(Ⅶ) to insoluble 99 Tc(Ⅳ),and they can be easily delivered into a contaminated groundwater zone and facilitate in situ remediation.In this study,CMCstabilized nZVI showed higher reactivity than that using starch as the stabilizer.Batch experiments indicated that more than 99% of 99 Tc(Ⅶ)(CO=12 mg/mL) was reduced and removed from groundwater by CMC-stabilized nZVI with a CMC content of 0.2%(w/w) at a broad pH of 5-8.X-ray diffraction(XRD)and X-ray photoelectron spectroscopy(XPS) analyses further confirmed that 99Tc(Ⅶ)O4^-transformed into 99Tc(Ⅳ)O2(s).The presence of bicarbonate exhibited insignificant effect on Tc immobilization,while humic acid(HA) inhibited reaction mainly due to retardation on electron transfer and formation of Tc(IV)-HA complexes.More interesting,the immobilized Tc(Ⅳ) remained insoluble even after 120 d under anoxic condition,while only^21 % was remobilized when exposed to air.Therefore,biomacromolecules stabilized nZVI nanoparticles could be a viable alternative for in situ remediation of radioactive contamination in groundwater.展开更多
Nowadays,studies on the mechanism of macro-scopic nonlinear behavior of materials by accumulation of micro-scopic degradation are attracting more attention from researchers.Among numerous approaches,multiscale methods...Nowadays,studies on the mechanism of macro-scopic nonlinear behavior of materials by accumulation of micro-scopic degradation are attracting more attention from researchers.Among numerous approaches,multiscale methods have been proved as powerful and practical approaches in predicting macro-scopic material status by averaging and homogenizing physical information from associated micro-scopic mate-rial behavior.Usually in mechanical problem,the stress,consistent material modulus,and possible mate-rial state variables are quantities in interest through the upscaling process.However,the energy-related quantities are not studied much.Some initiative work has been done in the early year including but not limited to the Hill-Mandel condition in multiscale framework,which gives that the macro-scopic elastic strain energy density can be computed by volumetric averaging of that in the micro-scale.However,in the nonlinear analysis,the energy dissipation is an important quantity to measure the degradation status.In this manuscript,two typical multiscale methods,the first-order computational homogenization(FOCH)and reduced-order homogenization(ROH),are adopted to numerically analyze a fiber-reinforced compos-ite material with capability in material nonlinearity.With numerical experiments,it can be shown that energy dissipation is the same for both approaches.展开更多
In terfaces that exist in composites greatly influence their mechanical and conductive properties.There are usually three interface models to characterize the elastic and conductive properties of the interface in comp...In terfaces that exist in composites greatly influence their mechanical and conductive properties.There are usually three interface models to characterize the elastic and conductive properties of the interface in composites.For elastic problems,they are the interface stress model(ISM),linear spring model(LSM),and interphase model.For conductive problems,they are the high conducting(HC)interface model,low conducting(LC)interface model,and interphase model.For elastic problems with the interface effects,they can be divided into two types.The first kind of elastic problem concerns the solution of boundary value problems and aims to predict the effective properties of composites with interface effects.The second kind of elastic problem concerns the surface/interface stress effects on the elastic properties of nanostructured materials,which is usually characterized by the ISM.In this paper,three aspects in the elastic problems with interface effects are first reviewed,i.e.,equivalent relations among the three interface models,Eshelby formalism,and micromechanical frameworks.Special emphasis is placed on the ISM to show how classical models can be extended to the nano-scale by supplementing the interface elasticity to the basic equations of the classical elastic problems.Then,the conductive problems of the composites with the interface effects are also reviewed,and the general frameworks for predicting the effective conductivity of the composites are given.Finally,scaling laws depicting the size-dependent elastic and conductive properties of the composites are discussed.展开更多
The behaviors of a neutrally buoyant ellipsoidal particle in vortical flow confined by a microcavity are numerically studied using the Lattice-Boltzmann method.For specific initial position,an isolated ellipsoid may d...The behaviors of a neutrally buoyant ellipsoidal particle in vortical flow confined by a microcavity are numerically studied using the Lattice-Boltzmann method.For specific initial position,an isolated ellipsoid may develop a stable limit cycle orbit inside microcavity due to the interaction between particle and the carrier flow.It is observed that ellipsoidal particles of different shapes exhibit two different stable rotational modes depending on the initial orientation and lateral position.A prolate spheroid tends to enter a tumbling mode whereas an oblate spheroid is apt to achieve a rolling mode.The evolution of rotational velocities along the stable orbit is also analyzed for particles of different shapes.展开更多
In this study,we numerically investigate the droplet impact onto a thin liquid film deposited on a structured surface with square pillars and cavities.The time evolution of crown geometry is strongly affected by the s...In this study,we numerically investigate the droplet impact onto a thin liquid film deposited on a structured surface with square pillars and cavities.The time evolution of crown geometry is strongly affected by the surface structure.When the thickness of the liquid film is larger than the structure height,the expanding speed of the crown base radius is independent of the structure width.However,if the liquid film thickness is equal to the structure height,the crown base expands slower as the structure width increases.Surface structures have strong effects on the crown height and radius,and can prevent ejected filament from breaking into satellite droplets for certain cases.For the liquid film with the thickness equal to the pillar height,both the crown height and the radius exhibit non-monotonic behaviors as the pillar width increases.There exists one pillar width which produces the smallest crown height and the largest crown radius.展开更多
The coastal eco-city of Fuzhou in Southeastern China has experienced severe ozone(O_(3))episodes at times in recent years.In this study,three typical synoptic circulations types(CTs)that influenced more than 80%of O_(...The coastal eco-city of Fuzhou in Southeastern China has experienced severe ozone(O_(3))episodes at times in recent years.In this study,three typical synoptic circulations types(CTs)that influenced more than 80%of O_(3) polluted days in Fuzhou during 2014-2019 were identified using a subjective approach.The characteristics of meteorological conditions linked to photochemical formation and transport of O_(3) under the three CTs were summarized.Comprehensive Air Quality Model with extensions was applied to simulate O_(3) episodes and to quantify O_(3) sources from different regions in Fuzhou.When Fuzhou was located to the west of a high-pressure system(classified as“East-ridge”),more warm southwesterly currents flowed to Fuzhou,and the effects of cross-regional transport from Guangdong province and high local production promoted the occurrence of O_(3) episodes.Under a uniform pressure field with a low-pressure system occurring to the east of Fuzhou(defined as“East-low”),stagnant weather conditions caused the strongest local production of O_(3) in the atmospheric boundary layer.Controlled by high-pressure systems over the mainland(categorized as“Inland-high”),northerly airflows enhanced the contribution of cross-regional transport to O_(3) in Fuzhou.The abnormal increases of the“East-ridge”and“Inland-high”were closely related to O_(3) pollution in Fuzhou in April and May 2018,resulting in the annual maximum number of O_(3) polluted days during recent years.Furthermore,the rising number of autumn O_(3) episodes in 2017-2019 was mainly related to the“Inland-high”,indicating the aggravation of cross-regional transport and highlighting the necessity of enhanced regional collaboration and efforts in combating O_(3) pollution.展开更多
Nanovesicles have been demonstrated to be the key agents in therapeutic encapsulations for drug delivery and diagnostic area,and the effectiveness and efficiency of these applications strongly depend on the mechanical...Nanovesicles have been demonstrated to be the key agents in therapeutic encapsulations for drug delivery and diagnostic area,and the effectiveness and efficiency of these applications strongly depend on the mechanical properties of nanovesicles.Based on the Helfrich membrane theory,a theoretical investigation is conducted to explore the mechanical behaviors of pressurized elastic fluid nanovesicles during the indentation by a rigid cylindrical indenter.The effects of osmotic pressure,membrane bending rigidity,energy of adhesion bet ween the vesicle and substrate on the mechanical responses of the vesicle to the indentation are analyzed.It is found that the osmotic pressure dominates the mechanical behaviors of strongly pressurized nanovesicles as well as the effective vesicle stiffness and Young's modulus.Our results may have important implications on regulating the mechanical behaviors of inter-and intracellular nanovesicles which are crucial for particle-based drug delivery systems.展开更多
Atomically thin MoS_2 has draw n tremendous attention due to its great potential in a range of electronic devices such as photodetectors,field effect transistors( FET),and sensors. In the past few years,numerous metho...Atomically thin MoS_2 has draw n tremendous attention due to its great potential in a range of electronic devices such as photodetectors,field effect transistors( FET),and sensors. In the past few years,numerous methods including mechanical cleavage,liquid exfoliation,chemical vapor deposition( CVD)have been devoted to synthesizing tw o dimensional atomically thin MoS_2. Among these methods,CVD is the most promising method for preparing large-size and highly crystalline MoS_2 monolayers,exhibiting relatively good optical and electrical properties. Nevertheless,there are so many experiment parameters in CVD process that w e should take into account,w hich makes it still a challenge for us to grow large-scale,single-crystalline MoS_2 monolayer films suitable for practical applications. This review systematically summarized some synthetic strategies of MoS_2 by CVD in recent years. We also discussed in detail how these vital factors such as substrates,carrier gases,M o precursors,influenced the process of grow th,w hich w as expected to help us to controllably synthesize high-quality MoS_2 and other kinds of transition metal dichalcogenides including WS_2,VS_2,WSe_2 and so forth.展开更多
基金supported by the Natural Science Foundation Project of Chongqing Science and Technology Commission (CQ CSTC)(No.cstc2018jcyjAX0320)the Fundamental Research Funds for the Central Universities(No.2018CDXYCH0013)+1 种基金Financial supports from the National Nature Science Foundation of China(NSFC)(Nos.91647211 and No.51539001)the Innovative Research Group of NSFC(No.51721006)
文摘In this study,a novel class of niobium(Nb) doped titanate nanoflakes(TNFs) are fabricated through a onestep hydrothermal method.Nb doping affects the curving of titanate nanosheet,leading to the formation of nanoflake structure.In addition,Nb5+ filled in the interlayers of [TiO6] alters the light adsorption property of pristine titanate.The band gap of Nb-TNFs is narrowed to 2.85 eV,while neat titanate nano tubes(TNTs) is 3.4 eV.The enhanced visible light adsorption significantly enhances the visible-lightdriven activity of Nb-TNFs for ibuprofen(IBP) degradation.The pseudo-first order kinetics constant for Nb-TNFs is calculated to be 1.04 h^-1,while no obvious removal is observed for TNTs.Photo-generated holes(h^+) and hydroxyl radicals(·OH) are responsible for IBP degradation.The photocatalytic activity of Nb-TNFs depends on pH condition,and the optimal pH value is found to be 5.In addition,Nb-TNFs exhibited superior photo-stability during the reuse cycles.The results demonstrated Nb-TNFs are very promising in photocatalytic water purification.
基金Project supported by the National Natural Science Foundation of China(No.11802004)
文摘The droplet formation dynamics of a Newtonian liquid in a drop-on-demand (DOD) inkjet process is numerically investigated by using a volume-of-fluid (VOF) method. We focus on the nozzle geometry, wettability of the interior surface, and the fluid properties to achieve the stable droplet formation with higher velocity. It is found that a nozzle with contracting angle of 45° generates the most stable and fastest single droplet, which is beneficial for the enhanced printing quality and high-throughput printing rate. For this nozzle with the optimal geometry, we systematically change the wettability of the interior surface, i.e., different contact angles. As the contact angle increases, pinch-off time increases and the droplet speed reduces. Finally, fluids with different properties are investigated to identify the printability range.
基金partially supported by the National Natural Science Foundation of China(Nos.21906001 and 51721006)supported by MOE Key Laboratory of Resources and Environmental Systems Optimization(NCEPU)
文摘Hollow microsphere structure cobalt hydroxide(h-Co(OH)2) was synthesized via an optimized solvothermal-hydrothermal process and applied to activate peroxymonosulfate(PMS) for degradation of a typical pharmaceutically active compound,ibuprofen(IBP).The material characterizations confirmed the presence of the microscale hollow spheres with thin nanosheets shell in h-Co(OH)2,and the crystalline phase was assigned to a-Co(OH)2.h-Co(OH)2 could efficiently activate PMS for radicals production,and 98.6% of IBP was degraded at 10 min.The activation of PMS by h-Co(OH)2 was a pHindependent process,and pH 7 was the optimum condition for the activation-degradation system.Scavenger quenching test indicated that the sulfate radical(SO4^·-) was the primary reactive oxygen species for IBP degradation,which contributed to 75.7%.Fukui index(f^-) based on density functional theory(DFT) calculation predicted the active sites of IBP molecule for SO4^·- attack,and then IBP degradation pathway was proposed by means of intermediates identification and theoretical calculation.The developed hollow Co(OH)2 used to efficiently activate PMS is promising and innovative alternative for organic contaminants removal from water and wastewater.
基金supported by the National Natural Science Foundation of China(Grant Nos.11988102,12002005,11632001,11521202)the Science Challenge Project(Grant No.TZ2018001).
文摘Softening behavior of lath martensitic steels is related to the coarsening of laths and dislocation evolution during cyclic deformation.Involving the physical mechanism,we developed a dislocation-based model to study the cyclic plastic response for lath martensitic steels.For a block,we proposed an interfacial dislocation evolution model to physically present the interaction between mobile dislocations in the block and interfacial dislocations by considering the coarsening mechanism of the laths.Moreover,the evolution behavior of backstress caused by dislocation pile up at the block boundary has been considered.Then,a hierarchical model based on the elastic-viscoplastic self-consistent(EVPSC)theory is developed,which can realize the scale transition among representative volume element(RVE),prior austenite grains(PAGs)and blocks.According to the proposed model,the effective mechanical responses including the cyclic hysteretic loop and peak stress at different cycles for lath martensitic steel have been theoretically predicted and investigated.
基金supported by grants from the National Natural Science Foundation of China(Nos.31870946,31470916)
文摘Heterostructures are a series of nanomaterials combining different components into a single nanostructure. Au-FeOheterostructures have received considerable attentions because of their superior properties coming from both individual and combinational features of gold and iron oxide nanoparticles. Their intrinsically peculiar magnetic, optical properties, and structure designability greatly enhance and broaden their potential applications in catalysis, assay, multimodal imaging, and synergistic treatment for tumor. In this review, we systematically introduce the preparation methods of Au-FeOheterostructures and their potential applications in the biomedical field, focusing on the unique synergistic effect caused by the combination of gold and iron oxide structures. This review will provide insights into the structure control in adjusting the function of heterogeneous or hybrid material, such as Au-FeOheterostructures, to implement their biomedical applications.
基金financially supported by the National Natural Science Foundation of China(Nos.51101013,21374009,51971028,51590882 and 51631001)the State Key Project of Research and Development of China(No.2017YFA0206301)。
文摘Lightweight nanocomposites consisting of magnetic and dielectric units aroused intensive interest as potential high performance electromagnetic wave absorbing materials.In this work,we report a facile and efficient method to fabricate(Co,SiO_(2))/PPy composites with tunable electromagnetic properties.The absorbing properties and effective absorbing bandwidth can be regulated by controlling the content of SiO_(2) in composites.The composite shows a maximum reflection loss(RL)of-65.31 d B at 11.12 GHz with a thickness of 3.002 mm when SiO_(2) being 22 wt.%.The effective absorbing bandwidth reaches up to 5.1 GHz(8.91-14.01 GHz),which covers the entire X band(8-12 GHz).The improved impedance matching,high interfacial polarization and complex electromagnetic synergy in the composites are the key factors giving rise to the higher efficient absorption.The PPy aerogel-based nanocomposites with controllable absorption performance,lower density and strong environmental adaptability will become attractive candidates as advanced microwave absorbing materials.
基金financially supported by the National Natural Science Foundation of China(Nos.U1704253 and U1908220)the Fundamental Research Funds for the Central Universities(No.N180206001)+1 种基金the Liaoning Revitalization Talents Program(No.XLYC1807177)the Zhejiang Provincial Natural Science Foundation of China(No.LR18E010001)。
文摘Listeria monocytogenes(L.monocytogenes)is one of the top five dangerous foodborne pathogens which widely exists in most raw food and has approximately 30%mortality rate in high-risk groups.Food safety caused by foodborne pathogens is still a major problem faced by humans in all world.The conventional analytical methods currently used involve complex bacteriological tests and usually take several days for incubation and analysis.Thus,in order to prevent the spread of disease,the development of a detection method with high speed,high accuracy and sensitivity is urgent and necessary.Herein,we developed an approach for the identification and magnetic capture of L.monocytogenes by using core@shell Fe_(3)O_(4)@silica nanoparticles terminated with hydroxyl or amine groups.Our results show that both amine-and hydroxyl-terminated Fe_(3)O_(4)@silica core@shell nanoparticles functionalized with specific antibodies,present 95.2%±6.2%and 98.6%±0.3%capture efficacies,respectively.However,without conjugating the specific antibodies,the hydroxyl-terminated Fe_(3)O_(4)@silica nanoparticles exhibit 17.6%±1.6%efficacy,while the amine-terminated one remains 93.2%±9.2%capture efficiency ascribed to the high affinity.This study quantitatively uncovers the specific and non-specific recognitions relevant to the molecular-scale physiochemical interactions between the microorganisms and the functionalized particles,and the results from this work can be generalized and extended to other bacterial species by changing antibodies,also have important implications in developing advanced analytic methods.
基金This work was supported in part by the National Natural Science Foundation of China(U1909206,61725305,61903007,62073196)in part by the S&T Program of Hebei(F2020203037).
文摘As a cross-cutting field between ocean development and multi-robot system(MRS),the underwater multi-robot system(UMRS)has gained increasing attention from researchers and engineers in recent decades.In this paper,we present a comprehensive survey of cooperation issues,one of the key components of UMRS,from the perspective of the emergence of new functions.More specifically,we categorize the cooperation in terms of task-space,motion-space,measurement-space,as well as their combination.Further,we analyze the architecture of UMRS from three aspects,i.e.,the performance of the individual underwater robot,the new functions of underwater robots,and the technical approaches of MRS.To conclude,we have discussed related promising directions for future research.This survey provides valuable insight into the reasonable utilization of UMRS to attain diverse underwater tasks in complex ocean application scenarios.
基金financially supported by the Tencent Foundation through the XPLORER PRIZE,Chinathe National Natural Science Foundation of China(51671003)+3 种基金the National Basic Research Program of China(2016YFB0100201)start-up support from Peking Universitythe Young Thousand Talented Programthe computation support from Jincai Zhao's group of Institute of Chemistry,Chinese Academy of Sciences。
文摘Building highly active and stable noble metal single atom(MSA)catalyst onto photocatalyst materials for nitrogen reduction reaction(NRR)and CO2 reduction reaction(CRR)is a key to future renewable energy conversion and storage technologies.Here we present a design strategy to optimize the stability and electronic property of noble metal single atoms(MSAs,M=Rh,Pd,Ag,Ir,Pt,Au)catalyst supported on g-C3N4 and 2H-MoS2 photocatalysts towards NRR and CRR.Our results indicate that the MSAs tend to be trapped at the anion-vacancy sites of photocatalyst rather than the pristine photocatalyst surface.This anion vacancy can promise the MSAs with an optimized electron-captured ability in the photoexcitation process,thus decreasing the energy barriers of NRR and CRR on MSAs.Especially,it is revealed that the N-vacancy-stabilized Ir SA on g-C3N4 and the S-vacancy-stabilized RhSA on 2H-MoS2 own the lowest energy barrier in NRR.However,for CRR,the HCOOH is the main product on MSAs supported by gC3N4 and 2H-MoS2.The N-vacancy-stabilized PdSA on g-C3N4 and the S-vacancy-stabilized AuSA on 2H-MoS2 show the lowest energy barrier for HCOOH production in CRR.This finding offers an approach to design specific active MSA centres on photocatalysts by the anion vacancy engineering.
基金Innovative Research Group of the National Natural Science Foundation of China(NFSC)(No.51721006)China Postdoctoral Science Foundation(No.2017M620132)
文摘A novel carbon quantum dots modified potassium titanate nanotubes(CQDs/K2 Ti6 O13)composite photocatalyst was synthesized by hydrothermal treatment combined with calcination.X-ray diffraction(XRD)pattern and transmission electron microscopy(TEM)indicated formation of potassium titanate nanotubes and successful deposition of CQDs onto K2 Ti6 O13.The photocatalytic performance of CQDs/K2 Ti6 O13 composite was evaluated by degradation of amoxicillin(AMX)under the irradiation of visible light and lights with the wavelengths of 365,385,420,450,485,520,595 and 630 nm.The results showed that the photocatalytic activity of CQDs/K2 Ti6 O13 hybrid material was greatly enhanced compared with the neat K2 Ti6 O13 calcined at 300℃.The narrowed band gap energy(Eg)and transfer of photo-excited electron by CQDs inhibited the immediate combination of electron-hole pairs,thus promoting photocatalytic activity.Moreover,CQ,Ds/K2 Ti6 O13 exhibited a broad spectrum of photocatalytic ability and it was interesting that the photocatalytic activity decreased with the increase of the irradiation wavelength.Reactive oxygen species(ROS)quenching tests suggested the hole(h^+)and hydroxyl radical(^·OH)played the primary roles in photocatalytic degradation of AMX.Moreover,CQ.Ds/K2 Ti6 O13 showed good reusability for AMX photocatalytic degradation after five successive runs.This study proposed an available method for titanate nanomaterials modification,and the developed novel CQDs/K2 Ti6 O13hyb rid material is p ro mising fo r potential application on antibiotics removal fro m water and wastewater.
基金partially supported by the National Natural Science Foundation of China(No.41230638)a grant from the USDA AAES 2015 Hatch and Multistate funding program
文摘Reductive immobilization of radioactive pertechnetate(99TcO4^-) in simulated groundwater was studied by prepared carboxymethyl cellulose(CMC) and starch stabilized zero valent iron nanoparticles(nZVI),and long-term remobilization of reduced Tc was also evaluated under anoxic and oxic conditions.The stabilized nZVI can effectively reduce soluble 99Tc(Ⅶ) to insoluble 99 Tc(Ⅳ),and they can be easily delivered into a contaminated groundwater zone and facilitate in situ remediation.In this study,CMCstabilized nZVI showed higher reactivity than that using starch as the stabilizer.Batch experiments indicated that more than 99% of 99 Tc(Ⅶ)(CO=12 mg/mL) was reduced and removed from groundwater by CMC-stabilized nZVI with a CMC content of 0.2%(w/w) at a broad pH of 5-8.X-ray diffraction(XRD)and X-ray photoelectron spectroscopy(XPS) analyses further confirmed that 99Tc(Ⅶ)O4^-transformed into 99Tc(Ⅳ)O2(s).The presence of bicarbonate exhibited insignificant effect on Tc immobilization,while humic acid(HA) inhibited reaction mainly due to retardation on electron transfer and formation of Tc(IV)-HA complexes.More interesting,the immobilized Tc(Ⅳ) remained insoluble even after 120 d under anoxic condition,while only^21 % was remobilized when exposed to air.Therefore,biomacromolecules stabilized nZVI nanoparticles could be a viable alternative for in situ remediation of radioactive contamination in groundwater.
基金the National Natural Science Foundation of China(Grant No.11988102)is gratefully acknowledged.
文摘Nowadays,studies on the mechanism of macro-scopic nonlinear behavior of materials by accumulation of micro-scopic degradation are attracting more attention from researchers.Among numerous approaches,multiscale methods have been proved as powerful and practical approaches in predicting macro-scopic material status by averaging and homogenizing physical information from associated micro-scopic mate-rial behavior.Usually in mechanical problem,the stress,consistent material modulus,and possible mate-rial state variables are quantities in interest through the upscaling process.However,the energy-related quantities are not studied much.Some initiative work has been done in the early year including but not limited to the Hill-Mandel condition in multiscale framework,which gives that the macro-scopic elastic strain energy density can be computed by volumetric averaging of that in the micro-scale.However,in the nonlinear analysis,the energy dissipation is an important quantity to measure the degradation status.In this manuscript,two typical multiscale methods,the first-order computational homogenization(FOCH)and reduced-order homogenization(ROH),are adopted to numerically analyze a fiber-reinforced compos-ite material with capability in material nonlinearity.With numerical experiments,it can be shown that energy dissipation is the same for both approaches.
基金the National Natural Science Foundation of China(Grant Nos.11988102,11872004,and 91848201).
文摘In terfaces that exist in composites greatly influence their mechanical and conductive properties.There are usually three interface models to characterize the elastic and conductive properties of the interface in composites.For elastic problems,they are the interface stress model(ISM),linear spring model(LSM),and interphase model.For conductive problems,they are the high conducting(HC)interface model,low conducting(LC)interface model,and interphase model.For elastic problems with the interface effects,they can be divided into two types.The first kind of elastic problem concerns the solution of boundary value problems and aims to predict the effective properties of composites with interface effects.The second kind of elastic problem concerns the surface/interface stress effects on the elastic properties of nanostructured materials,which is usually characterized by the ISM.In this paper,three aspects in the elastic problems with interface effects are first reviewed,i.e.,equivalent relations among the three interface models,Eshelby formalism,and micromechanical frameworks.Special emphasis is placed on the ISM to show how classical models can be extended to the nano-scale by supplementing the interface elasticity to the basic equations of the classical elastic problems.Then,the conductive problems of the composites with the interface effects are also reviewed,and the general frameworks for predicting the effective conductivity of the composites are given.Finally,scaling laws depicting the size-dependent elastic and conductive properties of the composites are discussed.
基金by the National Natural Science Foundation of China(Grants 11988102 and 91852112)the Challenge Program(Grant JCKY2016212A501).
文摘The behaviors of a neutrally buoyant ellipsoidal particle in vortical flow confined by a microcavity are numerically studied using the Lattice-Boltzmann method.For specific initial position,an isolated ellipsoid may develop a stable limit cycle orbit inside microcavity due to the interaction between particle and the carrier flow.It is observed that ellipsoidal particles of different shapes exhibit two different stable rotational modes depending on the initial orientation and lateral position.A prolate spheroid tends to enter a tumbling mode whereas an oblate spheroid is apt to achieve a rolling mode.The evolution of rotational velocities along the stable orbit is also analyzed for particles of different shapes.
基金Project supported by the National Natural Science Foundation of China(Nos.11988102,91848201,11872004,and 11802004)
文摘In this study,we numerically investigate the droplet impact onto a thin liquid film deposited on a structured surface with square pillars and cavities.The time evolution of crown geometry is strongly affected by the surface structure.When the thickness of the liquid film is larger than the structure height,the expanding speed of the crown base radius is independent of the structure width.However,if the liquid film thickness is equal to the structure height,the crown base expands slower as the structure width increases.Surface structures have strong effects on the crown height and radius,and can prevent ejected filament from breaking into satellite droplets for certain cases.For the liquid film with the thickness equal to the pillar height,both the crown height and the radius exhibit non-monotonic behaviors as the pillar width increases.There exists one pillar width which produces the smallest crown height and the largest crown radius.
基金supported by the National Key Research and Development Program of China(Nos.2018YFC0213204,2018YFC0213506).
文摘The coastal eco-city of Fuzhou in Southeastern China has experienced severe ozone(O_(3))episodes at times in recent years.In this study,three typical synoptic circulations types(CTs)that influenced more than 80%of O_(3) polluted days in Fuzhou during 2014-2019 were identified using a subjective approach.The characteristics of meteorological conditions linked to photochemical formation and transport of O_(3) under the three CTs were summarized.Comprehensive Air Quality Model with extensions was applied to simulate O_(3) episodes and to quantify O_(3) sources from different regions in Fuzhou.When Fuzhou was located to the west of a high-pressure system(classified as“East-ridge”),more warm southwesterly currents flowed to Fuzhou,and the effects of cross-regional transport from Guangdong province and high local production promoted the occurrence of O_(3) episodes.Under a uniform pressure field with a low-pressure system occurring to the east of Fuzhou(defined as“East-low”),stagnant weather conditions caused the strongest local production of O_(3) in the atmospheric boundary layer.Controlled by high-pressure systems over the mainland(categorized as“Inland-high”),northerly airflows enhanced the contribution of cross-regional transport to O_(3) in Fuzhou.The abnormal increases of the“East-ridge”and“Inland-high”were closely related to O_(3) pollution in Fuzhou in April and May 2018,resulting in the annual maximum number of O_(3) polluted days during recent years.Furthermore,the rising number of autumn O_(3) episodes in 2017-2019 was mainly related to the“Inland-high”,indicating the aggravation of cross-regional transport and highlighting the necessity of enhanced regional collaboration and efforts in combating O_(3) pollution.
基金Financial support for this work was provided by the National Natural Science Foundation of China(Grant Nos.11872005 and 11521202).
文摘Nanovesicles have been demonstrated to be the key agents in therapeutic encapsulations for drug delivery and diagnostic area,and the effectiveness and efficiency of these applications strongly depend on the mechanical properties of nanovesicles.Based on the Helfrich membrane theory,a theoretical investigation is conducted to explore the mechanical behaviors of pressurized elastic fluid nanovesicles during the indentation by a rigid cylindrical indenter.The effects of osmotic pressure,membrane bending rigidity,energy of adhesion bet ween the vesicle and substrate on the mechanical responses of the vesicle to the indentation are analyzed.It is found that the osmotic pressure dominates the mechanical behaviors of strongly pressurized nanovesicles as well as the effective vesicle stiffness and Young's modulus.Our results may have important implications on regulating the mechanical behaviors of inter-and intracellular nanovesicles which are crucial for particle-based drug delivery systems.
基金Sponsored by the National Key R&D Program of China(Grant Nos.2017YFA0206301 and 2016YFA0200102)the National Natural Science Foundation of China(Grant Nos.51631001,51590882,51672010 and 81421004)
文摘Atomically thin MoS_2 has draw n tremendous attention due to its great potential in a range of electronic devices such as photodetectors,field effect transistors( FET),and sensors. In the past few years,numerous methods including mechanical cleavage,liquid exfoliation,chemical vapor deposition( CVD)have been devoted to synthesizing tw o dimensional atomically thin MoS_2. Among these methods,CVD is the most promising method for preparing large-size and highly crystalline MoS_2 monolayers,exhibiting relatively good optical and electrical properties. Nevertheless,there are so many experiment parameters in CVD process that w e should take into account,w hich makes it still a challenge for us to grow large-scale,single-crystalline MoS_2 monolayer films suitable for practical applications. This review systematically summarized some synthetic strategies of MoS_2 by CVD in recent years. We also discussed in detail how these vital factors such as substrates,carrier gases,M o precursors,influenced the process of grow th,w hich w as expected to help us to controllably synthesize high-quality MoS_2 and other kinds of transition metal dichalcogenides including WS_2,VS_2,WSe_2 and so forth.
