Two Gd_(2)complexes,namely[Gd_(2)(dbm)_(2)(HL_(1))_(2)(CH_(3)OH)_(2)]·4CH_(3)OH(1)and[Gd_(2)(dbm)_(2)(L_(2))_(2)(CH_(3)OH)_(2)]·2CH_(3)OH(2),where H_(3)L_(1)=(Z)-N'-[4-(diethylamino)-2-hydroxybenzylidene...Two Gd_(2)complexes,namely[Gd_(2)(dbm)_(2)(HL_(1))_(2)(CH_(3)OH)_(2)]·4CH_(3)OH(1)and[Gd_(2)(dbm)_(2)(L_(2))_(2)(CH_(3)OH)_(2)]·2CH_(3)OH(2),where H_(3)L_(1)=(Z)-N'-[4-(diethylamino)-2-hydroxybenzylidene]-2-hydroxyacetohydrazide,H_(2)L_(2)=(E)-N'-(5-bromo-2-hydroxy-3-methoxybenzylidene)nicotinohydrazide,Hdbm=dibenzoylmethane,have been constructed by adopting the solvothermal method.Structural characterization unveils that both complexes 1 and 2 are constituted by two Gd^(3+)ions,two dbm-ions,two CH_(3)OH molecules,and two polydentate Schiff-base ligands(HL_(1)^(2-)or L_(2)^(2-)).In addition,complex 1 contains four free methanol molecules,whereas complex 2 harbors two free methanol molecules.By investigating the interactions between complexes 1 and 2 and four types of bacteria(Bacillus subtilis,Escherichia coli,Staphylococcus aureus,Candida albicans),it was found that both complexes 1 and 2 exhibited potent antibacte-rial activities.The interaction mechanisms between the ligands H_(3)L_(1),H_(2)L_(2),complexes 1 and 2,and calf thymus DNA(CT-DNA)were studied using ultraviolet-visible spectroscopy,fluorescence titration,and cyclic voltammetry.The results demonstrated that both complexes 1 and 2 can intercalate into CT-DNA molecules,thereby inhibiting bacterial proliferation to achieve the antibacterial effects.CCDC:2401116,1;2401117,2.展开更多
Intergrowth ferroelectric semiconductors with excellent spontaneous polarization field are highly promising piezo-photocatalytic candidate materials.In addition,developing structural design and revealing polarization ...Intergrowth ferroelectric semiconductors with excellent spontaneous polarization field are highly promising piezo-photocatalytic candidate materials.In addition,developing structural design and revealing polarization enhancement in-depth mechanism are top priorities.Herein,we introduce the intergrowth ferroelectrics Bi_(7)Ti_(4)NbO_(21)thin-layer nanosheets for piezo-photocatalytic CO_(2)reduction.Density functional theory(DFT)calculations indicate that interlayer lattice mismatch leads to increased tilting and rotation angle of Ti/NbO_(6)octahedra on perovskite-like layers,serving as the main reason for increased polarization.Furthermore,the tilting and rotation angle of the interlayer octahedron further increase under stress,suggesting a stronger driving force generated to facilitate charge carrier separation efficiency.Meanwhile,Bi_(7)Ti_(4)NbO_(21)nanosheets provide abundant active sites to effectively adsorb CO_(2)and acquire sensitive stress response,thereby presenting synergistically advanced piezo-photocatalytic CO_(2)reduction activity with a high CO generation rate of 426.97μmol g^(-1)h^(-1).Our work offers new perspectives and directions for initiating and investigating the mechanisms of high-performance intergrowth piezo-photocatalysts.展开更多
This paper employs the Direct Finite Element Squared(DFE2)method to develop Sparse Polynomial Chaos Expansions(SPCE)models for analyzing the electromechanical properties of multiscale piezoelectric structures.By incor...This paper employs the Direct Finite Element Squared(DFE2)method to develop Sparse Polynomial Chaos Expansions(SPCE)models for analyzing the electromechanical properties of multiscale piezoelectric structures.By incorporating variations in piezoelectric and elastic constants,the DFE2 method is utilized to simulate the statistical characteristics—such as expected values and standard deviations—of electromechanical properties,including Mises stress,maximum in-plane principal strain,electric potential gradient,and electric potential,under varying parameters.This approach achieves a balance between computational efficiency and accuracy.Different SPCE models are used to investigate the influence of piezoelectric and elastic constants on multiscale piezoelectric materials.Additionally,the multiscale parameterization study investigates how microscale material properties affect the macroscopic response of these structures and materials.展开更多
Automatic pancreas segmentation plays a pivotal role in assisting physicians with diagnosing pancreatic diseases,facilitating treatment evaluations,and designing surgical plans.Due to the pancreas’s tiny size,signifi...Automatic pancreas segmentation plays a pivotal role in assisting physicians with diagnosing pancreatic diseases,facilitating treatment evaluations,and designing surgical plans.Due to the pancreas’s tiny size,significant variability in shape and location,and low contrast with surrounding tissues,achieving high segmentation accuracy remains challenging.To improve segmentation precision,we propose a novel network utilizing EfficientNetV2 and multi-branch structures for automatically segmenting the pancreas fromCT images.Firstly,an EfficientNetV2 encoder is employed to extract complex and multi-level features,enhancing the model’s ability to capture the pancreas’s intricate morphology.Then,a residual multi-branch dilated attention(RMDA)module is designed to suppress irrelevant background noise and highlight useful pancreatic features.And re-parameterization Visual Geometry Group(RepVGG)blocks with amulti-branch structure are introduced in the decoder to effectively integrate deep features and low-level details,improving segmentation accuracy.Furthermore,we apply re-parameterization to the model,reducing computations and parameters while accelerating inference and reducing memory usage.Our approach achieves average dice similarity coefficient(DSC)of 85.59%,intersection over union(IoU)of 75.03%,precision of 85.09%,and recall of 86.57%on the NIH pancreas dataset.Compared with other methods,our model has fewer parameters and faster inference speed,demonstrating its enormous potential in practical applications of pancreatic segmentation.展开更多
Complex physical and chemical reactions during CO_(2)sequestration alter the microscopic pore structure of geological formations,impacting sequestration stability.To investigate CO_(2)sequestration dynamics,comprehens...Complex physical and chemical reactions during CO_(2)sequestration alter the microscopic pore structure of geological formations,impacting sequestration stability.To investigate CO_(2)sequestration dynamics,comprehensive physical simulation experiments were conducted under varied pressures,coupled with assessments of changes in mineral composition,ion concentrations,pore morphology,permeability,and sequestration capacity before and after experimentation.Simultaneously,a method using NMR T2spectra changes to measure pore volume shift and estimate CO_(2)sequestration is introduced.It quantifies CO_(2)needed for mineralization of soluble minerals.However,when CO_(2)dissolves in crude oil,the precipitation of asphaltene compounds impairs both seepage and storage capacities.Notably,the impact of dissolution and precipitation is closely associated with storage pressure,with a particularly pronounced influence on smaller pores.As pressure levels rise,the magnitude of pore alterations progressively increases.At a pressure threshold of 25 MPa,the rate of change in small pores due to dissolution reaches a maximum of 39.14%,while precipitation results in a change rate of-58.05%for small pores.The observed formation of dissolution pores and micro-cracks during dissolution,coupled with asphaltene precipitation,provides crucial insights for establishing CO_(2)sequestration parameters and optimizing strategies in low permeability reservoirs.展开更多
Double-resonance Raman(DRR)scattering in two-di-mensional(2D)materials describes the intravalley or intervalley scattering of an electron or a hole excited by incident photons.Although the presence of defects can prov...Double-resonance Raman(DRR)scattering in two-di-mensional(2D)materials describes the intravalley or intervalley scattering of an electron or a hole excited by incident photons.Although the presence of defects can provide additional momentum and influence the scat-tering process involving one or two phonons,only the idealized defects without any structural details are considered in tra-ditional DRR theory.Here,the second-order DRR spectra of WSe_(2) monolayer with different types of defects are calculated involving the combinations of acoustic and optical phonons in the vicinity of K(K')and M points of the Brillouin zone.The electronic band structures are modified due to the presence of defects,and the band unfolding method is adopted to show the bending of valence and conduction bands for the defective WSe_(2) monolayers.The associ-ated phononic band structures also exhibit different changes in phonon dispersion curves,re-sulting in different DRR spectra corresponding to the different types of defects in the WSe_(2) monolayers.For example,the existence of W vacancy in the WSe_(2) monolayer would result in downshifts in vibrational frequencies and asymmetrical broadenings in linewidths for most combination modes due to the dramatic changes in contour shape of electronic valleys at K and K'.Moreover,the scattering from K to Q is found to be forbidden for the two Se vacan-cies because of the elevation of conduction band at the Q point.Our work highlights the role of defect structures in the intervalley scattering and may provide better understanding in the underlying physics of DRR process in 2D materials.展开更多
As cathode materials for alkali-ion batteries,sodium manganese oxides have been receiving considerable and continuous attention in recent decades.In this work,the structure and environment-dependent stability of NaMn_...As cathode materials for alkali-ion batteries,sodium manganese oxides have been receiving considerable and continuous attention in recent decades.In this work,the structure and environment-dependent stability of NaMn_(2)O_(4) surface were studied based on the first principles calculations.The surface stability diagram of NaMn_(2)O_(4) involving various different terminations of(100),(110)and(111)surfaces was constructed,and the stability of these different terminations could be compared as a function of chemical environment.It is found that the(100)-MnO and(111)-ONa terminations are two more stable terminations under the investigated chemical conditions.And the surface energies of(110)surfaces are negative under the investigated chemical potential,hence,(110)surfaces are unstable.The surface energy of NaMn_(2)O_(4) as a function of O chemical potential is also investigated under constant Na chemical potential.The structure relaxation indicates that the surface rumpling and surface reconstruction can affect the electronic structure of the surface,thereby reducing surface energy and stabilizing the surface.Furthermore,the Wulff shape of NaMn_(2)O_(4) was also constructed based on Gibbs-Wulff theorem.展开更多
Typical p-n junctions have emerged as a promising strategy for contending with charge carrier recombination in solar conversion.However,the photo-corrosion and unsuitable energy band positions still hinder their pract...Typical p-n junctions have emerged as a promising strategy for contending with charge carrier recombination in solar conversion.However,the photo-corrosion and unsuitable energy band positions still hinder their practical application for hydrogen production from water in photoelectrochemical systems.Here,an in-situ photo-oxidation method is proposed for achieving self-adapting activation of BiVO_(4)-based photoanodes with surface-encapsulated CuGaS_(2)particles by the ZnO layer.The self-adapting activation demotes the energy band positions of CuGaS_(2),establishing an S-scheme structure with BiVO_(4),resulting in an efficient p-n junction photoanode.The optimal sample exhibits enhanced photocurrent and an onset potential cathodically shifted by~300 mV compared with BiVO_(4),which is attributed to significantly enhanced charge transport and transfer efficiencies.As expected,it attains the highest photocurrent value of 5.87 mA·cm^(-2),aided by a hole scavenger at 1.23 V versus a reversible hydrogen electrode,which significantly surpasses that of BiVO_(4)(4.32 mA·cm^(-2)).展开更多
Controlled photocatalytic conversion of CO_(2) into premium fuel such as methane(CH4)offers a sustainable pathway towards a carbon energy cycle.However,the photocatalytic efficiency and selectivity are still unsatisfa...Controlled photocatalytic conversion of CO_(2) into premium fuel such as methane(CH4)offers a sustainable pathway towards a carbon energy cycle.However,the photocatalytic efficiency and selectivity are still unsatisfactory due to the limited availability of active sites on the current photocatalysts.To resolve this issue,the design of oxygen vacancies(OVs)in metal-oxide semiconductors is an effective option.Herein,in situ deposition of TiO_(2) onto SiO_(2) nanospheres to construct a SiO_(2)@TiO_(2) core-shell structure was performed to modulate the oxygen vacancy concentrations.Meanwhile,charge redistribution led to the formation of abundant OV-regulated Ti-Ti(Ti-OV-Ti)dual sites.It is revealed that Ti-OV-Ti dual sites served as the key active site for capturing the photogenerated electrons during light-driven CO_(2) reduction reaction(CO_(2)RR).Such electron-rich active sites enabled efficient CO_(2) adsorption and activation,thus lowering the energy barrier associated with the rate-determining step.More importantly,the formation of a highly stable*CHO intermediate at Ti-OV-Ti dual sites energetically favored the reaction pathway towards the production of CH4 rather than CO,thereby facilitating the selective product of CH_(4).As a result,SiO_(2)@TiO_(2)-50 with an optimized oxygen vacancy concentration of 9.0% showed a remarkable selectivity(90.32%)for CH_(4) production with a rate of 13.21μmol g^(-1) h^(-1),which is 17.38-fold higher than that of pristine TiO_(2).This study provides a new avenue for engineering superior photocatalysts through a rational methodology towards selective reduction of CO_(2).展开更多
We theoretically investigate the electronic structure of cylindrical magnetic topological insulator quantum wires in MnBi_(2)Te_(4).Our study reveals the emergence of topological surface states in the ferromagnetic ph...We theoretically investigate the electronic structure of cylindrical magnetic topological insulator quantum wires in MnBi_(2)Te_(4).Our study reveals the emergence of topological surface states in the ferromagnetic phase,characterized by spin-polarized subbands resulting from intrinsic magnetization.In the antiferromagnetic phase,we identify the coexistence of three distinct types of topological states,encompassing both surface states and central states.展开更多
The influence of the growth of rare earth on the viscosity during the uniform cooling of CaO-SiO_(2-)CaF_(2)-Ce_(2)O_(3)slag was investigated by the high temperature viscometer.The results show that Ce_(2)O_(3)affects...The influence of the growth of rare earth on the viscosity during the uniform cooling of CaO-SiO_(2-)CaF_(2)-Ce_(2)O_(3)slag was investigated by the high temperature viscometer.The results show that Ce_(2)O_(3)affects the viscosity variedly before and after the break temperature.At higher temperatures Ce_(2)O_(3)reduces the viscosity.When the temperature is below the break temperature,at a Ce_(2)O_(3)content of≥3 mol%,a rareearth crystalline phase is observed during the slag cooling process,and the break temperature progressively increases with the increase of Ce_(2)O_(3)concentration.There are no crystallized rare earths in the slag under the condition of Ce_(2)O_(3)concentration lower than 3 mol%.Too low or too high CaF_(2)content is found to be unfavorable for rare-earth crystallisation.The increase of Ce_(2)O_(3)content facilitates the depolymerization of silica-oxygen tetrahedral structure.Ca-F bond exists between structural units,weakening the flow resistance of structural units and lowering the viscosity of slag.展开更多
Herein we report novel photocatalysts ZnIn_(2)S_(4)-Ag-LaFeO_(3) with the core-shell structured materials prepared by hydrothermal method.In order to improve the efficiency of photocatalytic degradation of pollutants,...Herein we report novel photocatalysts ZnIn_(2)S_(4)-Ag-LaFeO_(3) with the core-shell structured materials prepared by hydrothermal method.In order to improve the efficiency of photocatalytic degradation of pollutants,LaFeO_(3) was prepared by hydrothermal followed by calcination,and further Ag nanoparticle(NP)was loaded onto the spherical structure of LaFeO_(3) by photolysis of silver nitrate,and finally the spherical Znln_(2)S_(4)-Ag-LaFeO_(3) photocatalyst was prepared by hydrothermal method again.The structure and properties of the as-prepared materials were characterized by X-ray photoelectron spectroscopy,ultraviolet-visible absorption spectroscopy,X-ray diffraction,scanning electron microscopy and fluorescence spectra.The results show that the synthesized composite photocatalysts display a significant improvement in photocatalytic efficiency relative to the single LaFeO_(3) and ZnIn_(2)S_(4)and form a core-shell structure.Furthermore,the effect of the ratio of each component on the photocatalytic efficiency was investigated in detail,and it is discovered that at an Methylene Blue(MB)concentration of 0.219 mol/L,the degradation rate of MB is 95%at 120 min using 0.02 g of catalyst with an ideal ZnIn_(2)S_(4):Ag:LaFeO_(3)ratio of 10:0.5:1.The possible mechanisms to improve the photocatalytic efficiency were explored.展开更多
Photoelectrochemical water oxidation(PEC-WO)as a green and sustainable route to produce H_(2)O_(2)has attracted extensive attentions.However,water oxidation to H_(2)O_(2)via a 2e^(-) pathway is thermodynamically more ...Photoelectrochemical water oxidation(PEC-WO)as a green and sustainable route to produce H_(2)O_(2)has attracted extensive attentions.However,water oxidation to H_(2)O_(2)via a 2e^(-) pathway is thermodynamically more difficult than to O_(2)via a 4e^(-)pathway.Herein,with a series of BiVO_(4)-based photoanodes,the decisive factors determining the PEC activity and selectivity are elucidated,combining a comprehensive experimental and theoretical investigations.It is discovered that the ZnO/BiVO_(4)photoanode(ZnO/BVO)forms a Type-Ⅱheterojunction in energy level alignment.The accelerated photogenerated charge separation/transfer dynamics generates denser surface holes and higher surface photovoltage.Therefore,the activity of water oxidation reaction is promoted.The selectivity of PEC-WO to H_(2)O_(2)is found to be potential-dependent,i.e.,at the lower potentials(PEC-dominated),surface hole density determines the selectivity;and at the higher potentials(electrochemical-dominated),surface reaction barriers govern the selectivity.For the ZnO/BVO heterojunction photoanode,the higher surface hole density facilitates the generation of OH·and the subsequent OH·/OH·coupling to form H_(2)O_(2),thus rising up with potentials;at the higher potentials,the 2-electron pathway barrier over ZnO/BVO surface is lower than over BVO surface,which benefits from the electronic structure regulation by the underlying ZnO alleviating the over-strong adsorption of^(*)OH on BVO,thus,the two-electron pathway to produce H_(2)O_(2)is more favored than on BVO surface.This work highlights the crucial role of band energy structure of semiconductors on both PEC reaction activity and selectivity,and the knowledge gained is expected to be extended to other photoeletrochemical reactions.展开更多
Photocatalytic synthesis of hydrogen peroxide(H_(2)O_(2))has emerged as a promising approach because of its simplicity and environmental benefits.However,significant challenges remain obstacles to their advancement,su...Photocatalytic synthesis of hydrogen peroxide(H_(2)O_(2))has emerged as a promising approach because of its simplicity and environmental benefits.However,significant challenges remain obstacles to their advancement,such as the rapid recombination of photogenerated charge carriers and sluggish surface redox reactions on nonmetallic organic catalysts.Metal-based organic catalysts with tunable electronic structures are considered ideal for exploring the mechanisms and structure-performance relationships in H_(2)O_(2) synthesis.This review summarizes the fundamental principles of photocatalytic H_(2)O_(2) synthesis via oxygen reduction and water oxidation reactions.Recent advancements in electronic structure tuning strategies for metal-based organic catalysts are critically examined,focusing on their impact on light absorption range,photogenerated carrier separation,O_(2) activation,and the selective generation of H_(2)O_(2).In addition,this review comprehensively evaluates the applications of sacrificial agents in photocatalytic reaction systems and offers insights into the future development of metal-based organic catalysts for H_(2)O_(2) photosynthesis.展开更多
As an extreme physical condition,high pressure serves as a potent means to substantially modify the interatomic distances and bonding patterns within condensed matter,thereby enabling the macroscopic manipulation of m...As an extreme physical condition,high pressure serves as a potent means to substantially modify the interatomic distances and bonding patterns within condensed matter,thereby enabling the macroscopic manipulation of material properties.We employed the CALYPSO method to predict the stable structures of RbB_(2)C_(4)across the pressure range from 0 GPa to 100 GPa and investigated its physical properties through first-principles calculations.Specially,we found four novel structures,namely,P6_(3)/mcm-,Amm2-,P1-,and I4/mmm-RbB_(2)C_(4).Under pressure conditions,electronic structure calculations reveal that all of them exhibit metallic characteristics.The calculation results of formation enthalpy show that the P6_(3)/mcm structure can be synthesized within the pressure range of 0–40 GPa.Specially,the Amm2,P1,and I4/mmm structures can be synthesized above 4 GPa,6 GPa,10 GPa,respectively.Moreover,the estimated Vickers hardness value of I4/mmm-RbB_(2)C_(4)compound is 47 GPa,suggesting that it is a superhard material.Interestingly,this study uncovers the continuous transformation of the crystal structure of RbB_(2)C_(4)from a layered configuration to folded and tubular forms,ultimately attaining a stabilized cage-like structure under the pressure span of 0–100 GPa.The application of pressure offers a formidable impetus for the advancement and innovation in condensed matter physics,facilitating the exploration of novel states and functions of matter.展开更多
Eu^(2+)ions'occupancy in a-cordierite structure has been a hot research topic.In this study,Eu^(2+)ions were introduced intoα-Mg_(2)Al_(4)Si_(5)O_(18)structure by glass skeleton modification relaxation crystalliz...Eu^(2+)ions'occupancy in a-cordierite structure has been a hot research topic.In this study,Eu^(2+)ions were introduced intoα-Mg_(2)Al_(4)Si_(5)O_(18)structure by glass skeleton modification relaxation crystallization route,and optimizing Eu^(2+)ions'occupancy was induced by changing the skeleton structure through Al^(3+)content and B^(3+)-P^(5+)double substituting 2Si4+.Three occupied luminescent structures'evolution was verified by combining photo luminescence spectra and lattice parameters.The results show that within the range of Al^(3+)content lower than 1.1 mol or B^(3+)-P^(5+)content higher than 3 mol%,the lattice parameters are dominated by the a/b direction.This is beneficial for Eu^(2+)ions to occupy structural channel sites and Ca^(2+)sites,which forms occupied luminescent structures Eu^(2+)_(vac)and Eu^(2+)_(Ca).When the Al^(3+)content is higher than 1.1 mol or B^(3+)-P^(5+)content is lower than 3 mol%,the lattice parameters are dominated by c direction,which is more conducive to Eu^(2+)ions occupying Mg2+sites and occupied luminescent structure Eu^(2+)_(Mg)formation.By sensitivity calculations,occupancy priority of Eu^(2+)ions are derived as Eu^(2+)_(Ca)>Eu^(2+)_(vac)>Eu^(2+)_(Mg).This study provides an effective strategy to modulate Eu^(2+)occupancy thereby achieving single-component white light emission.展开更多
In response to the limitations of conventional chemical synthesis methods for the structural modulation of nanomaterials,an innovative high magnetic field-assisted wet chemical synthesis method was proposed to prepare...In response to the limitations of conventional chemical synthesis methods for the structural modulation of nanomaterials,an innovative high magnetic field-assisted wet chemical synthesis method was proposed to prepare NiFe_(2)O_(4)/Fe_(2)O_(3) heterostructures.It is found that the high-energy physical field could induce a more homogeneous morphology of NiFe_(2)O_(4)/Fe_(2)O_(3),accompanied by phase transformation from Fe_(2)O_(3) to NiFe_(2)O_(4).As a result,the optimized structure obtained under the magnetic field endows NiFe_(2)O_(4)/Fe_(2)O_(3) with enhanced performance for the lithium-ion battery anode,as evidenced by an increase of 16%(1200 mA·h/g)in discharge capacity and 24% in ultra-stable cycling performance(capacity retention of 97.1%).These results highlight the feasibility of high magnetic fields in modulating material structure and enhancing lithium storage performance.展开更多
Guided by the fundamental principles of the whole petroleum system,the control of tectonism,sedimentation,and diagenesis on hydrocarbon accumulation in a rifted basin is studied using the data of petroleum geology and...Guided by the fundamental principles of the whole petroleum system,the control of tectonism,sedimentation,and diagenesis on hydrocarbon accumulation in a rifted basin is studied using the data of petroleum geology and exploration of the second member of the Paleogene Kongdian Formation(Kong-2 Member)in the Cangdong Sag,Bohai Bay Basin,China.It is clarified that the circle structure and circle effects are the marked features of a continental fault petroliferous basin,and they govern the orderly distribution of conventional and unconventional hydrocarbons in the whole petroleum systems of the rifted basin.Tectonic circle zones control sedimentary circle zones,while sedimentary circle zones and diagenetic circle zones control the spatial distribution of favorable reservoirs,thereby determining the orderly distribution of hydrocarbon accumulations in various circles.A model for the integrated,systematic accumulation of conventional and unconventional hydrocarbons under a multi-circle structure of the whole petroleum system of continental rifted basin has been developed.It reveals that each sag of the rifted basin is an independent whole petroleum system and circle system,which encompasses multiple orderly circles of conventional and unconventional hydrocarbons controlled by the same source kitchen.From the outer circle to the middle circle and then to the inner circle,there is an orderly transition from structural and stratigraphic reservoirs,to lithological and structural-lithological reservoirs,and finally to tight oil/gas and shale oil/gas enrichment zones.The significant feature of the whole petroleum system is the orderly control of hydrocarbons by multi-circle stratigraphic coupling,with the integrated,orderly distribution of conventional and unconventional reserves being the inevitable result of the multi-layered interaction within the whole petroleum system.This concept of multi-circle stratigraphic coupling for the orderly,integrated accumulation of conventional and unconventional hydrocarbons has guided significant breakthroughs in the overall,three-dimensional exploration and shale oil exploration in the Cangdong Sag.展开更多
Single-atom catalysts are promising for H_(2)O_(2) photosynthesis from O_(2) and H_(2)O,but their efficiency is still limited by the ill-defined electronic structure.In this study,Co single-atoms with unique four plan...Single-atom catalysts are promising for H_(2)O_(2) photosynthesis from O_(2) and H_(2)O,but their efficiency is still limited by the ill-defined electronic structure.In this study,Co single-atoms with unique four planar N-coordination and one axial P-coordination(Co-N_(4)P_(1))are decorated on the lateral edges of nanorod-like crystalline g-C_(3)N_(4)(CCN)photocatalysts.Significantly,the electronic structures of central Co as active sites for O_(2) reduction reaction(ORR)and planar N-coordinator as active sites for H_(2)O oxidation reaction(WOR)in Co-N_(4)P_(1) can be well regulated by the synergetic effects of introducing axial P-coordinator,in contrast to the decorated Co single-atoms with only four planar N-coordination(Co-N_(4)).Specifically,directional photoelectron accumulation at central Co active sites,induced by an introduced midgap level in Co-N_(4)P_(1),mediates the ORR active sites from 4e–-ORR-selective terminal–NH_(2) sites to 2e–-ORR-selective Co sites,moreover,an elevated d-band center of Co 3d orbital strengthens ORR intermediate*OOH adsorption,thus jointly facilitating a highly selective and active 2e^(–)-ORR pathway to H_(2)O_(2) photosynthesis.Simultaneously,a downshifted p-band center of N_(2)p orbital in Co-N_(4)P_(1) weakens WOR intermediate*OH adsorption,thus enabling a preferable 2e^(–)-WOR pathway toward H_(2)O_(2) photosynthesis.Subsequently,Co-N_(4)P_(1) exhibits exceptional H_(2)O_(2) photosynthesis efficiency,reaching 295.6μmol g^(-1) h^(-1) with a remarkable solar-to-chemical conversion efficiency of 0.32%,which is 15 times that of Co-N_(4)(19.2μmol g^(-1) h^(-1))and 10 times higher than CCN(27.6μmol g^(-1) h^(-1)).This electronic structure modulation on single-atom catalysts offers a promising strategy for boosting the activity and selectivity of H_(2)O_(2) photosynthesis.展开更多
Multi-scale lamellar structure significantly improves toughness of Ti_(2)AlNb based alloys,which are inher-ently brittle intermetallics,without compromising their strength.This structure was achieved through-B2-transu...Multi-scale lamellar structure significantly improves toughness of Ti_(2)AlNb based alloys,which are inher-ently brittle intermetallics,without compromising their strength.This structure was achieved through-B2-transus-forging(TBTF)combined with O+B2 two-phase region heat treatments.Various types of multi-scale lamellar structures were obtained by controlling the cooling rate after TBTF.These variations were mainly attributed to differences in the distribution,content,and size of the thick lamellar O phase and the size and crystallographic orientation of B2 grain.By analyzing the microstructural characteristics and crystallographic orientation near the crack propagation path,it was found that the crack propaga-tion resistance of thick lamellae,sub grain and grain boundaries(GBs)O phase increased sequentially,accompanied by more tortuous crack propagation path.Moreover,B2 grains with high misorientation significantly deflected the crack propagation by cleavage ridges between adjoining cleavage planes.Addi-tionally,the development of numerous secondary cleavage ridges,resulting from the transition through varying secondary cleavage planes in distinct sub B2 grains,further hindered the quick propagation of cracks.It was clarified that the cleavage planes were dominantly belonging to{110}.These findings pro-vided valuable guidance for the design of damage tolerance strategies for Ti_(2)AlNb-based intermetallics.展开更多
文摘Two Gd_(2)complexes,namely[Gd_(2)(dbm)_(2)(HL_(1))_(2)(CH_(3)OH)_(2)]·4CH_(3)OH(1)and[Gd_(2)(dbm)_(2)(L_(2))_(2)(CH_(3)OH)_(2)]·2CH_(3)OH(2),where H_(3)L_(1)=(Z)-N'-[4-(diethylamino)-2-hydroxybenzylidene]-2-hydroxyacetohydrazide,H_(2)L_(2)=(E)-N'-(5-bromo-2-hydroxy-3-methoxybenzylidene)nicotinohydrazide,Hdbm=dibenzoylmethane,have been constructed by adopting the solvothermal method.Structural characterization unveils that both complexes 1 and 2 are constituted by two Gd^(3+)ions,two dbm-ions,two CH_(3)OH molecules,and two polydentate Schiff-base ligands(HL_(1)^(2-)or L_(2)^(2-)).In addition,complex 1 contains four free methanol molecules,whereas complex 2 harbors two free methanol molecules.By investigating the interactions between complexes 1 and 2 and four types of bacteria(Bacillus subtilis,Escherichia coli,Staphylococcus aureus,Candida albicans),it was found that both complexes 1 and 2 exhibited potent antibacte-rial activities.The interaction mechanisms between the ligands H_(3)L_(1),H_(2)L_(2),complexes 1 and 2,and calf thymus DNA(CT-DNA)were studied using ultraviolet-visible spectroscopy,fluorescence titration,and cyclic voltammetry.The results demonstrated that both complexes 1 and 2 can intercalate into CT-DNA molecules,thereby inhibiting bacterial proliferation to achieve the antibacterial effects.CCDC:2401116,1;2401117,2.
基金support from the Natural Science Foundation of Jiangsu Province(BK20220596)Innovative science and technology platform project of cooperation between Yangzhou City and Yangzhou University,China(No.YZ202026305)+1 种基金Natural Science Foundation of China(21922202,21673202 and 22272147)the Priority Academic Program Development of Jiangsu Higher Education Institutions.
文摘Intergrowth ferroelectric semiconductors with excellent spontaneous polarization field are highly promising piezo-photocatalytic candidate materials.In addition,developing structural design and revealing polarization enhancement in-depth mechanism are top priorities.Herein,we introduce the intergrowth ferroelectrics Bi_(7)Ti_(4)NbO_(21)thin-layer nanosheets for piezo-photocatalytic CO_(2)reduction.Density functional theory(DFT)calculations indicate that interlayer lattice mismatch leads to increased tilting and rotation angle of Ti/NbO_(6)octahedra on perovskite-like layers,serving as the main reason for increased polarization.Furthermore,the tilting and rotation angle of the interlayer octahedron further increase under stress,suggesting a stronger driving force generated to facilitate charge carrier separation efficiency.Meanwhile,Bi_(7)Ti_(4)NbO_(21)nanosheets provide abundant active sites to effectively adsorb CO_(2)and acquire sensitive stress response,thereby presenting synergistically advanced piezo-photocatalytic CO_(2)reduction activity with a high CO generation rate of 426.97μmol g^(-1)h^(-1).Our work offers new perspectives and directions for initiating and investigating the mechanisms of high-performance intergrowth piezo-photocatalysts.
基金supported by the Zhumadian 2023 Major Science and Technology Special Project(Grant No.ZMDSZDZX2023002)the Postgraduate Education Reform and Quality Improvement Project of Henan Province(Grant No.YJS2023JD52).
文摘This paper employs the Direct Finite Element Squared(DFE2)method to develop Sparse Polynomial Chaos Expansions(SPCE)models for analyzing the electromechanical properties of multiscale piezoelectric structures.By incorporating variations in piezoelectric and elastic constants,the DFE2 method is utilized to simulate the statistical characteristics—such as expected values and standard deviations—of electromechanical properties,including Mises stress,maximum in-plane principal strain,electric potential gradient,and electric potential,under varying parameters.This approach achieves a balance between computational efficiency and accuracy.Different SPCE models are used to investigate the influence of piezoelectric and elastic constants on multiscale piezoelectric materials.Additionally,the multiscale parameterization study investigates how microscale material properties affect the macroscopic response of these structures and materials.
基金supported by the Science and Technology Innovation Programof Hunan Province(Grant No.2022RC1021)the Hunan Provincial Natural Science Foundation Project(Grant No.2023JJ60124)+1 种基金the Changsha Natural Science Foundation Project(Grant No.kq2202265)the key project of the Hunan Provincial of Education(Grant No.22A0255).
文摘Automatic pancreas segmentation plays a pivotal role in assisting physicians with diagnosing pancreatic diseases,facilitating treatment evaluations,and designing surgical plans.Due to the pancreas’s tiny size,significant variability in shape and location,and low contrast with surrounding tissues,achieving high segmentation accuracy remains challenging.To improve segmentation precision,we propose a novel network utilizing EfficientNetV2 and multi-branch structures for automatically segmenting the pancreas fromCT images.Firstly,an EfficientNetV2 encoder is employed to extract complex and multi-level features,enhancing the model’s ability to capture the pancreas’s intricate morphology.Then,a residual multi-branch dilated attention(RMDA)module is designed to suppress irrelevant background noise and highlight useful pancreatic features.And re-parameterization Visual Geometry Group(RepVGG)blocks with amulti-branch structure are introduced in the decoder to effectively integrate deep features and low-level details,improving segmentation accuracy.Furthermore,we apply re-parameterization to the model,reducing computations and parameters while accelerating inference and reducing memory usage.Our approach achieves average dice similarity coefficient(DSC)of 85.59%,intersection over union(IoU)of 75.03%,precision of 85.09%,and recall of 86.57%on the NIH pancreas dataset.Compared with other methods,our model has fewer parameters and faster inference speed,demonstrating its enormous potential in practical applications of pancreatic segmentation.
基金support of the National Natural Science Foundation of China(Grant Nos.52174030,52474042 and 52374041)the Postgraduate Innovation Fund Project of Xi'an Shiyou University(No.YCX2411001)the Natural Science Basic Research Program of Shaanxi(Program Nos.2024JCYBMS-256 and 2022JQ-528)。
文摘Complex physical and chemical reactions during CO_(2)sequestration alter the microscopic pore structure of geological formations,impacting sequestration stability.To investigate CO_(2)sequestration dynamics,comprehensive physical simulation experiments were conducted under varied pressures,coupled with assessments of changes in mineral composition,ion concentrations,pore morphology,permeability,and sequestration capacity before and after experimentation.Simultaneously,a method using NMR T2spectra changes to measure pore volume shift and estimate CO_(2)sequestration is introduced.It quantifies CO_(2)needed for mineralization of soluble minerals.However,when CO_(2)dissolves in crude oil,the precipitation of asphaltene compounds impairs both seepage and storage capacities.Notably,the impact of dissolution and precipitation is closely associated with storage pressure,with a particularly pronounced influence on smaller pores.As pressure levels rise,the magnitude of pore alterations progressively increases.At a pressure threshold of 25 MPa,the rate of change in small pores due to dissolution reaches a maximum of 39.14%,while precipitation results in a change rate of-58.05%for small pores.The observed formation of dissolution pores and micro-cracks during dissolution,coupled with asphaltene precipitation,provides crucial insights for establishing CO_(2)sequestration parameters and optimizing strategies in low permeability reservoirs.
基金supported by the National Natural Sci-ence Foundation of China(No.22174135,No.21790352)the National Key R&D Program of China(No.2021YFA1500500,No.2016YFA0200600)+4 种基金the Strategic Priority Research Program of Chinese Academy of Sciences(No.XDB36000000)Anhui Initiative in Quantum Information Technologies(No.AHY090100)CAS Project for Young Scientists in Basic Research(No.YSBR-054)Innovation Program for Quantum Science and Technology(No.2021ZD0303301)the Fundamental Research Funds for the Central Universities.
文摘Double-resonance Raman(DRR)scattering in two-di-mensional(2D)materials describes the intravalley or intervalley scattering of an electron or a hole excited by incident photons.Although the presence of defects can provide additional momentum and influence the scat-tering process involving one or two phonons,only the idealized defects without any structural details are considered in tra-ditional DRR theory.Here,the second-order DRR spectra of WSe_(2) monolayer with different types of defects are calculated involving the combinations of acoustic and optical phonons in the vicinity of K(K')and M points of the Brillouin zone.The electronic band structures are modified due to the presence of defects,and the band unfolding method is adopted to show the bending of valence and conduction bands for the defective WSe_(2) monolayers.The associ-ated phononic band structures also exhibit different changes in phonon dispersion curves,re-sulting in different DRR spectra corresponding to the different types of defects in the WSe_(2) monolayers.For example,the existence of W vacancy in the WSe_(2) monolayer would result in downshifts in vibrational frequencies and asymmetrical broadenings in linewidths for most combination modes due to the dramatic changes in contour shape of electronic valleys at K and K'.Moreover,the scattering from K to Q is found to be forbidden for the two Se vacan-cies because of the elevation of conduction band at the Q point.Our work highlights the role of defect structures in the intervalley scattering and may provide better understanding in the underlying physics of DRR process in 2D materials.
基金Project(BK20241969)supported by the Natural Science Foundation of Jiangsu Province,ChinaProject(51971249)supported by the National Natural Science Foundation of China。
文摘As cathode materials for alkali-ion batteries,sodium manganese oxides have been receiving considerable and continuous attention in recent decades.In this work,the structure and environment-dependent stability of NaMn_(2)O_(4) surface were studied based on the first principles calculations.The surface stability diagram of NaMn_(2)O_(4) involving various different terminations of(100),(110)and(111)surfaces was constructed,and the stability of these different terminations could be compared as a function of chemical environment.It is found that the(100)-MnO and(111)-ONa terminations are two more stable terminations under the investigated chemical conditions.And the surface energies of(110)surfaces are negative under the investigated chemical potential,hence,(110)surfaces are unstable.The surface energy of NaMn_(2)O_(4) as a function of O chemical potential is also investigated under constant Na chemical potential.The structure relaxation indicates that the surface rumpling and surface reconstruction can affect the electronic structure of the surface,thereby reducing surface energy and stabilizing the surface.Furthermore,the Wulff shape of NaMn_(2)O_(4) was also constructed based on Gibbs-Wulff theorem.
基金supported by the open fund from Key Lab of Eco-restoration of Regional Contaminated Environment(Shenyang University),Ministry of Education(No.KF-22-08)the National Natural Science Foundation of China(Nos.22003074 and 42177406)+1 种基金the Youth Innovation Promotion Association CAS,Guangdong Basic and Applied Basic Research Foundation(No.2023A1515011410)S.Liu gratefully acknowledges the financial support by the National Natural Science Foundation of China(No.52302223).
文摘Typical p-n junctions have emerged as a promising strategy for contending with charge carrier recombination in solar conversion.However,the photo-corrosion and unsuitable energy band positions still hinder their practical application for hydrogen production from water in photoelectrochemical systems.Here,an in-situ photo-oxidation method is proposed for achieving self-adapting activation of BiVO_(4)-based photoanodes with surface-encapsulated CuGaS_(2)particles by the ZnO layer.The self-adapting activation demotes the energy band positions of CuGaS_(2),establishing an S-scheme structure with BiVO_(4),resulting in an efficient p-n junction photoanode.The optimal sample exhibits enhanced photocurrent and an onset potential cathodically shifted by~300 mV compared with BiVO_(4),which is attributed to significantly enhanced charge transport and transfer efficiencies.As expected,it attains the highest photocurrent value of 5.87 mA·cm^(-2),aided by a hole scavenger at 1.23 V versus a reversible hydrogen electrode,which significantly surpasses that of BiVO_(4)(4.32 mA·cm^(-2)).
基金supported by the National Natural Science Foundation of China(No.21773089,22202037)the Science and Technology Development Plan Project of Jilin Province,China(No.20240101192JC)the Fundamental Research Funds for the Central Universities(No.2412023QD019).
文摘Controlled photocatalytic conversion of CO_(2) into premium fuel such as methane(CH4)offers a sustainable pathway towards a carbon energy cycle.However,the photocatalytic efficiency and selectivity are still unsatisfactory due to the limited availability of active sites on the current photocatalysts.To resolve this issue,the design of oxygen vacancies(OVs)in metal-oxide semiconductors is an effective option.Herein,in situ deposition of TiO_(2) onto SiO_(2) nanospheres to construct a SiO_(2)@TiO_(2) core-shell structure was performed to modulate the oxygen vacancy concentrations.Meanwhile,charge redistribution led to the formation of abundant OV-regulated Ti-Ti(Ti-OV-Ti)dual sites.It is revealed that Ti-OV-Ti dual sites served as the key active site for capturing the photogenerated electrons during light-driven CO_(2) reduction reaction(CO_(2)RR).Such electron-rich active sites enabled efficient CO_(2) adsorption and activation,thus lowering the energy barrier associated with the rate-determining step.More importantly,the formation of a highly stable*CHO intermediate at Ti-OV-Ti dual sites energetically favored the reaction pathway towards the production of CH4 rather than CO,thereby facilitating the selective product of CH_(4).As a result,SiO_(2)@TiO_(2)-50 with an optimized oxygen vacancy concentration of 9.0% showed a remarkable selectivity(90.32%)for CH_(4) production with a rate of 13.21μmol g^(-1) h^(-1),which is 17.38-fold higher than that of pristine TiO_(2).This study provides a new avenue for engineering superior photocatalysts through a rational methodology towards selective reduction of CO_(2).
基金Project sponsored by the Natural Science Foundation of Chongqing,China(Grant No.CSTB2024NSCQMSX0736)the Special Project of Chongqing Technology Innovation and Application Development(Major Project)(Grant No.CSTB2024TIAD-STX0035)the Research Foundation of Institute for Advanced Sciences of CQUPT(Grant No.E011A2022328)。
文摘We theoretically investigate the electronic structure of cylindrical magnetic topological insulator quantum wires in MnBi_(2)Te_(4).Our study reveals the emergence of topological surface states in the ferromagnetic phase,characterized by spin-polarized subbands resulting from intrinsic magnetization.In the antiferromagnetic phase,we identify the coexistence of three distinct types of topological states,encompassing both surface states and central states.
基金Project supported by the Inner Mongolia University of Science and Technology Basic Research Business Fee Project(2022QNJS068,2024QNJS132)Inner Mongolia Autonomous Region Scientific and Technological Achievements Transformation Project(CGZH2018153)+1 种基金Inner Mongolia Autonomous Region Science and Technology Innovation Guidance Incentive Fund(0406041703)Project of Natural Science Foundation of Inner Mongolia(2024SHZR2341)。
文摘The influence of the growth of rare earth on the viscosity during the uniform cooling of CaO-SiO_(2-)CaF_(2)-Ce_(2)O_(3)slag was investigated by the high temperature viscometer.The results show that Ce_(2)O_(3)affects the viscosity variedly before and after the break temperature.At higher temperatures Ce_(2)O_(3)reduces the viscosity.When the temperature is below the break temperature,at a Ce_(2)O_(3)content of≥3 mol%,a rareearth crystalline phase is observed during the slag cooling process,and the break temperature progressively increases with the increase of Ce_(2)O_(3)concentration.There are no crystallized rare earths in the slag under the condition of Ce_(2)O_(3)concentration lower than 3 mol%.Too low or too high CaF_(2)content is found to be unfavorable for rare-earth crystallisation.The increase of Ce_(2)O_(3)content facilitates the depolymerization of silica-oxygen tetrahedral structure.Ca-F bond exists between structural units,weakening the flow resistance of structural units and lowering the viscosity of slag.
基金Project supported by the National Natural Science Foundation of China(21101107,51173107)State Key Laboratory of Pollution Control and Resource Reuse Foundation(PCRRF19017)。
文摘Herein we report novel photocatalysts ZnIn_(2)S_(4)-Ag-LaFeO_(3) with the core-shell structured materials prepared by hydrothermal method.In order to improve the efficiency of photocatalytic degradation of pollutants,LaFeO_(3) was prepared by hydrothermal followed by calcination,and further Ag nanoparticle(NP)was loaded onto the spherical structure of LaFeO_(3) by photolysis of silver nitrate,and finally the spherical Znln_(2)S_(4)-Ag-LaFeO_(3) photocatalyst was prepared by hydrothermal method again.The structure and properties of the as-prepared materials were characterized by X-ray photoelectron spectroscopy,ultraviolet-visible absorption spectroscopy,X-ray diffraction,scanning electron microscopy and fluorescence spectra.The results show that the synthesized composite photocatalysts display a significant improvement in photocatalytic efficiency relative to the single LaFeO_(3) and ZnIn_(2)S_(4)and form a core-shell structure.Furthermore,the effect of the ratio of each component on the photocatalytic efficiency was investigated in detail,and it is discovered that at an Methylene Blue(MB)concentration of 0.219 mol/L,the degradation rate of MB is 95%at 120 min using 0.02 g of catalyst with an ideal ZnIn_(2)S_(4):Ag:LaFeO_(3)ratio of 10:0.5:1.The possible mechanisms to improve the photocatalytic efficiency were explored.
基金financially supported by the National Natural Science Foundation of China(22478211,22179067,22372017)the Major Fundamental Research Program of Natural Science Foundation of Shandong Province(ZR2022ZD10)。
文摘Photoelectrochemical water oxidation(PEC-WO)as a green and sustainable route to produce H_(2)O_(2)has attracted extensive attentions.However,water oxidation to H_(2)O_(2)via a 2e^(-) pathway is thermodynamically more difficult than to O_(2)via a 4e^(-)pathway.Herein,with a series of BiVO_(4)-based photoanodes,the decisive factors determining the PEC activity and selectivity are elucidated,combining a comprehensive experimental and theoretical investigations.It is discovered that the ZnO/BiVO_(4)photoanode(ZnO/BVO)forms a Type-Ⅱheterojunction in energy level alignment.The accelerated photogenerated charge separation/transfer dynamics generates denser surface holes and higher surface photovoltage.Therefore,the activity of water oxidation reaction is promoted.The selectivity of PEC-WO to H_(2)O_(2)is found to be potential-dependent,i.e.,at the lower potentials(PEC-dominated),surface hole density determines the selectivity;and at the higher potentials(electrochemical-dominated),surface reaction barriers govern the selectivity.For the ZnO/BVO heterojunction photoanode,the higher surface hole density facilitates the generation of OH·and the subsequent OH·/OH·coupling to form H_(2)O_(2),thus rising up with potentials;at the higher potentials,the 2-electron pathway barrier over ZnO/BVO surface is lower than over BVO surface,which benefits from the electronic structure regulation by the underlying ZnO alleviating the over-strong adsorption of^(*)OH on BVO,thus,the two-electron pathway to produce H_(2)O_(2)is more favored than on BVO surface.This work highlights the crucial role of band energy structure of semiconductors on both PEC reaction activity and selectivity,and the knowledge gained is expected to be extended to other photoeletrochemical reactions.
文摘Photocatalytic synthesis of hydrogen peroxide(H_(2)O_(2))has emerged as a promising approach because of its simplicity and environmental benefits.However,significant challenges remain obstacles to their advancement,such as the rapid recombination of photogenerated charge carriers and sluggish surface redox reactions on nonmetallic organic catalysts.Metal-based organic catalysts with tunable electronic structures are considered ideal for exploring the mechanisms and structure-performance relationships in H_(2)O_(2) synthesis.This review summarizes the fundamental principles of photocatalytic H_(2)O_(2) synthesis via oxygen reduction and water oxidation reactions.Recent advancements in electronic structure tuning strategies for metal-based organic catalysts are critically examined,focusing on their impact on light absorption range,photogenerated carrier separation,O_(2) activation,and the selective generation of H_(2)O_(2).In addition,this review comprehensively evaluates the applications of sacrificial agents in photocatalytic reaction systems and offers insights into the future development of metal-based organic catalysts for H_(2)O_(2) photosynthesis.
基金Project supported by the Jilin Provincial Science and Technology Development Joint Fund Project(Grant No.YDZJ202201ZYTS581)supported by the Scientific and Technological Research Project of Jilin Provincial Education Department(Grant No.JJKH20240077KJ).
文摘As an extreme physical condition,high pressure serves as a potent means to substantially modify the interatomic distances and bonding patterns within condensed matter,thereby enabling the macroscopic manipulation of material properties.We employed the CALYPSO method to predict the stable structures of RbB_(2)C_(4)across the pressure range from 0 GPa to 100 GPa and investigated its physical properties through first-principles calculations.Specially,we found four novel structures,namely,P6_(3)/mcm-,Amm2-,P1-,and I4/mmm-RbB_(2)C_(4).Under pressure conditions,electronic structure calculations reveal that all of them exhibit metallic characteristics.The calculation results of formation enthalpy show that the P6_(3)/mcm structure can be synthesized within the pressure range of 0–40 GPa.Specially,the Amm2,P1,and I4/mmm structures can be synthesized above 4 GPa,6 GPa,10 GPa,respectively.Moreover,the estimated Vickers hardness value of I4/mmm-RbB_(2)C_(4)compound is 47 GPa,suggesting that it is a superhard material.Interestingly,this study uncovers the continuous transformation of the crystal structure of RbB_(2)C_(4)from a layered configuration to folded and tubular forms,ultimately attaining a stabilized cage-like structure under the pressure span of 0–100 GPa.The application of pressure offers a formidable impetus for the advancement and innovation in condensed matter physics,facilitating the exploration of novel states and functions of matter.
基金Project supported by Anhui Natural Science(1808085ME136)。
文摘Eu^(2+)ions'occupancy in a-cordierite structure has been a hot research topic.In this study,Eu^(2+)ions were introduced intoα-Mg_(2)Al_(4)Si_(5)O_(18)structure by glass skeleton modification relaxation crystallization route,and optimizing Eu^(2+)ions'occupancy was induced by changing the skeleton structure through Al^(3+)content and B^(3+)-P^(5+)double substituting 2Si4+.Three occupied luminescent structures'evolution was verified by combining photo luminescence spectra and lattice parameters.The results show that within the range of Al^(3+)content lower than 1.1 mol or B^(3+)-P^(5+)content higher than 3 mol%,the lattice parameters are dominated by the a/b direction.This is beneficial for Eu^(2+)ions to occupy structural channel sites and Ca^(2+)sites,which forms occupied luminescent structures Eu^(2+)_(vac)and Eu^(2+)_(Ca).When the Al^(3+)content is higher than 1.1 mol or B^(3+)-P^(5+)content is lower than 3 mol%,the lattice parameters are dominated by c direction,which is more conducive to Eu^(2+)ions occupying Mg2+sites and occupied luminescent structure Eu^(2+)_(Mg)formation.By sensitivity calculations,occupancy priority of Eu^(2+)ions are derived as Eu^(2+)_(Ca)>Eu^(2+)_(vac)>Eu^(2+)_(Mg).This study provides an effective strategy to modulate Eu^(2+)occupancy thereby achieving single-component white light emission.
基金supported by the National Natural Science Foundation of China(No.52274294)the Fundamental Research Funds for the Central Universities,China(No.N2124007-1)the Fund of the State Key Laboratory of Solidification Processing in Northwestern Polytechnical University,China(No.SKLSP202101)。
文摘In response to the limitations of conventional chemical synthesis methods for the structural modulation of nanomaterials,an innovative high magnetic field-assisted wet chemical synthesis method was proposed to prepare NiFe_(2)O_(4)/Fe_(2)O_(3) heterostructures.It is found that the high-energy physical field could induce a more homogeneous morphology of NiFe_(2)O_(4)/Fe_(2)O_(3),accompanied by phase transformation from Fe_(2)O_(3) to NiFe_(2)O_(4).As a result,the optimized structure obtained under the magnetic field endows NiFe_(2)O_(4)/Fe_(2)O_(3) with enhanced performance for the lithium-ion battery anode,as evidenced by an increase of 16%(1200 mA·h/g)in discharge capacity and 24% in ultra-stable cycling performance(capacity retention of 97.1%).These results highlight the feasibility of high magnetic fields in modulating material structure and enhancing lithium storage performance.
基金Supported by the National Science and Technology Major Project of China(2024ZD1400101)China National Key Research and Development Project(2022YFF0801204)Major Science and Technology Project of CNPC(2023ZZ15YJ01,2021DJ0702)。
文摘Guided by the fundamental principles of the whole petroleum system,the control of tectonism,sedimentation,and diagenesis on hydrocarbon accumulation in a rifted basin is studied using the data of petroleum geology and exploration of the second member of the Paleogene Kongdian Formation(Kong-2 Member)in the Cangdong Sag,Bohai Bay Basin,China.It is clarified that the circle structure and circle effects are the marked features of a continental fault petroliferous basin,and they govern the orderly distribution of conventional and unconventional hydrocarbons in the whole petroleum systems of the rifted basin.Tectonic circle zones control sedimentary circle zones,while sedimentary circle zones and diagenetic circle zones control the spatial distribution of favorable reservoirs,thereby determining the orderly distribution of hydrocarbon accumulations in various circles.A model for the integrated,systematic accumulation of conventional and unconventional hydrocarbons under a multi-circle structure of the whole petroleum system of continental rifted basin has been developed.It reveals that each sag of the rifted basin is an independent whole petroleum system and circle system,which encompasses multiple orderly circles of conventional and unconventional hydrocarbons controlled by the same source kitchen.From the outer circle to the middle circle and then to the inner circle,there is an orderly transition from structural and stratigraphic reservoirs,to lithological and structural-lithological reservoirs,and finally to tight oil/gas and shale oil/gas enrichment zones.The significant feature of the whole petroleum system is the orderly control of hydrocarbons by multi-circle stratigraphic coupling,with the integrated,orderly distribution of conventional and unconventional reserves being the inevitable result of the multi-layered interaction within the whole petroleum system.This concept of multi-circle stratigraphic coupling for the orderly,integrated accumulation of conventional and unconventional hydrocarbons has guided significant breakthroughs in the overall,three-dimensional exploration and shale oil exploration in the Cangdong Sag.
文摘Single-atom catalysts are promising for H_(2)O_(2) photosynthesis from O_(2) and H_(2)O,but their efficiency is still limited by the ill-defined electronic structure.In this study,Co single-atoms with unique four planar N-coordination and one axial P-coordination(Co-N_(4)P_(1))are decorated on the lateral edges of nanorod-like crystalline g-C_(3)N_(4)(CCN)photocatalysts.Significantly,the electronic structures of central Co as active sites for O_(2) reduction reaction(ORR)and planar N-coordinator as active sites for H_(2)O oxidation reaction(WOR)in Co-N_(4)P_(1) can be well regulated by the synergetic effects of introducing axial P-coordinator,in contrast to the decorated Co single-atoms with only four planar N-coordination(Co-N_(4)).Specifically,directional photoelectron accumulation at central Co active sites,induced by an introduced midgap level in Co-N_(4)P_(1),mediates the ORR active sites from 4e–-ORR-selective terminal–NH_(2) sites to 2e–-ORR-selective Co sites,moreover,an elevated d-band center of Co 3d orbital strengthens ORR intermediate*OOH adsorption,thus jointly facilitating a highly selective and active 2e^(–)-ORR pathway to H_(2)O_(2) photosynthesis.Simultaneously,a downshifted p-band center of N_(2)p orbital in Co-N_(4)P_(1) weakens WOR intermediate*OH adsorption,thus enabling a preferable 2e^(–)-WOR pathway toward H_(2)O_(2) photosynthesis.Subsequently,Co-N_(4)P_(1) exhibits exceptional H_(2)O_(2) photosynthesis efficiency,reaching 295.6μmol g^(-1) h^(-1) with a remarkable solar-to-chemical conversion efficiency of 0.32%,which is 15 times that of Co-N_(4)(19.2μmol g^(-1) h^(-1))and 10 times higher than CCN(27.6μmol g^(-1) h^(-1)).This electronic structure modulation on single-atom catalysts offers a promising strategy for boosting the activity and selectivity of H_(2)O_(2) photosynthesis.
基金supported by the National Natural Science Foundation of China(No.52275380).
文摘Multi-scale lamellar structure significantly improves toughness of Ti_(2)AlNb based alloys,which are inher-ently brittle intermetallics,without compromising their strength.This structure was achieved through-B2-transus-forging(TBTF)combined with O+B2 two-phase region heat treatments.Various types of multi-scale lamellar structures were obtained by controlling the cooling rate after TBTF.These variations were mainly attributed to differences in the distribution,content,and size of the thick lamellar O phase and the size and crystallographic orientation of B2 grain.By analyzing the microstructural characteristics and crystallographic orientation near the crack propagation path,it was found that the crack propaga-tion resistance of thick lamellae,sub grain and grain boundaries(GBs)O phase increased sequentially,accompanied by more tortuous crack propagation path.Moreover,B2 grains with high misorientation significantly deflected the crack propagation by cleavage ridges between adjoining cleavage planes.Addi-tionally,the development of numerous secondary cleavage ridges,resulting from the transition through varying secondary cleavage planes in distinct sub B2 grains,further hindered the quick propagation of cracks.It was clarified that the cleavage planes were dominantly belonging to{110}.These findings pro-vided valuable guidance for the design of damage tolerance strategies for Ti_(2)AlNb-based intermetallics.
