The Pfaffian property of graphs is of fundamental importance in graph theory,as it precisely characterizes those graphs for which the number of perfect matchings can be computed in polynomial time with respect to the ...The Pfaffian property of graphs is of fundamental importance in graph theory,as it precisely characterizes those graphs for which the number of perfect matchings can be computed in polynomial time with respect to the number of edges.The study of Pfaffian graphs originated from the enumeration of perfect matching in planar graphs.References[5,6,8]demonstrated that every planar graph is Pfaffian.Therefore,the Pfaffian property and planarity of graphs play a vital role in modern matching theory.This paper contributes a complete characterization of the Pfaffian property and planarity of connected Cayley graphs over the dicyclic group T_(4n) of order 4n(n≥3),shows that the Cayley graph Cay(T_(4n),S)is Pfaffian if and only if n is odd and S={a^(k_(1)),a^(2n−k_(1)),ba^(k_(2)),ba^(n+k_(2))},where 1≤k_(1)≤n−1,0≤k_(2)≤n−1 and(k_(1),n)=1,and furthermore,shows that Cay(T4n,S)is never planar.展开更多
The movement of interacting faults within the Earth’s crust during earthquakes may cause significant structural damage.Large earthquake fault surfaces are often planar or a combination of several planar fault segment...The movement of interacting faults within the Earth’s crust during earthquakes may cause significant structural damage.Large earthquake fault surfaces are often planar or a combination of several planar fault segments.This study analyses the interaction between a non-planar and a planar fault,where the faults are inclined,buried,creeping and strike-slip in nature.The non-planar fault is infinite and formed by two interconnected planar segments,while the planar fault is finite.The present analysis adduces the movement of interacting faults in a composite structure comprised of an elastic layer nested on a visco-elastic substrate of Maxwell medium.The significant effect of various affecting parameters viz.inclination of the faults,velocity of the fault movement,depth of the faults from the free surface,distance between the faults and the non-planarity of the fault has been discussed and also compared.The amount of stress and surface shear strain is restored after the creeping movement.The graphical representation of the effect of non-planarity of the fault on stress-strain accumulation has been established.Analytical solutions are obtained using Laplace transform and Green’s function techniques,supported by numerical simulations.The obtained results provide insights into fault interaction process and have important implications for assessing seismic hazard potential in viscoelastic media.The study of such earthquake fault dynamical models may give some ideas about the nature of stress-strain accumulation or release in the system and help us to observe the mechanism of lithosphere-asthenosphere boundary.展开更多
A new benzothiadiazole-based D-A-D hole transport material(DTBT)has been designed and synthesized with a more planar structure by introducing of thiophene bridges.The results indicate a lower band gap and quite higher...A new benzothiadiazole-based D-A-D hole transport material(DTBT)has been designed and synthesized with a more planar structure by introducing of thiophene bridges.The results indicate a lower band gap and quite higher hole mobility for the DTBT.Furthermore,the enhancement in molecular planarity with simple thiophene unit increases the hole mobility of DTBT(8.77×10^-4cm^2 V^-1s^-1)by about 40%.And when DTBT is used as hole transport material in perovskite solar cells,the photoelectric conversion efficiency of the corresponding dopant-free devices is also significantly improved compared with that of the conventional BT model molecule without thiophene.In terms of device stability,DTBT-based devices show a favorable long-term stability,which keep 83%initial efficiency after 15 days.Therefore,the introducing of thiophene bridges in D-A-D typed HTMs can improve the molecular planarity effectively,thereby increasing the hole mobility and improving device performance.展开更多
We study the effects of the planarity and heterogeneity of networks on evolutionary two-player symmetric games by considering four different kinds of networks, including two types of heterogeneous networks: the weight...We study the effects of the planarity and heterogeneity of networks on evolutionary two-player symmetric games by considering four different kinds of networks, including two types of heterogeneous networks: the weighted planar stochastic lattice(a planar scale-free network) and the random uncorrelated scale-free network with the same degree distribution as the weighted planar stochastic lattice; and two types of homogeneous networks: the hexagonal lattice and the random regular network with the same degree k_0= 6 as the hexagonal lattice. Using extensive computer simulations, we found that both the planarity and heterogeneity of the network have a significant influence on the evolution of cooperation, either promotion or inhibition, depending not only on the specific kind of game(the Harmony, Snowdrift, Stag Hunt or Prisoner's Dilemma games), but also on the update rule(the Fermi, replicator or unconditional imitation rules).展开更多
To date,extensive efforts have been devoted to designing new conjugated polymers with long alkyl or ethylene glycol sidechains.However,these sidechains are insulators,limiting further performance enhancement in doped ...To date,extensive efforts have been devoted to designing new conjugated polymers with long alkyl or ethylene glycol sidechains.However,these sidechains are insulators,limiting further performance enhancement in doped conjugated polymers.Moreover,the most widely used chlorinated solvents are toxic,limiting the practical applications of many conjugated polymers.Here,we report a water/alcohol processable n-type conjugated polymer P(Py2FT),featuring side chain-free cationic backbones.P(Py2FT)exhibits a high n-type electrical conductivity of up to 28.1 S cm^(−1)and a high thermoelectric power factor of up to 28.7μWm^(−1)K^(−2),comparable to some conventional n-type conjugated polymers reported recently.More importantly,cationic polymers display tight molecular packings and interesting enhanced backbone planarity after n-doping,which,we envision,provides a new research direction to address the sidechain issue in conventional conjugated polymers.Our work demonstrates that sidechain-free cationic polymers have great potential for green-solvent-processed heavily doped organic electronics.展开更多
Self-assembly of dyes has become a flexible strategy to modulate their photophysical properties.H-aggregates show great potential to increase heat generation,while the precise designing of H-aggregates as efficient ph...Self-assembly of dyes has become a flexible strategy to modulate their photophysical properties.H-aggregates show great potential to increase heat generation,while the precise designing of H-aggregates as efficient photothermal agents is still challenging.Herein,a quinoline cyanine(QCy)is developed for constructing stable H-aggregated nanoparticles(NPs)to significantly enhance photostability and photothermal conversion efficiency(PCE).With symmetrical rigid planar quinoline structures,QCy has a small and symmetrical dihedral angle(11.9°),which ensures excellent molecular planarity.In aqueous solution,the planar QCy can form closeπ–πmolecular stacking,and fast self-assemble into stable H-aggregates even at low concentrations(1×10−7 M).QCy H-aggregates are sphere-like NPs(QCy NPs)with an average diameter of 120 nm and exhibit high stability.H-aggregation of QCy significantly enhances PCE from 20.1%(non-H-aggregated QCy)to 63.8%(QCy NPs).In addition,the positive charge of quaternarized quinoline provides mitochondrial anchoring ability,which further enhances the photothermal effect.With high PCE and tumor accumulation,QCy NPs in low-doses have been successfully used in photoacoustic imaging-guided tumor photothermal therapy.展开更多
With the use of a chemical-mechanical polishing （CMP） simulator verified by testing data from a foundry, the effect of dummy fill characteristics, such as fill size, fill density and fill shape, on CMP planarity is ...With the use of a chemical-mechanical polishing （CMP） simulator verified by testing data from a foundry, the effect of dummy fill characteristics, such as fill size, fill density and fill shape, on CMP planarity is analyzed. The results indicate that dummy density has a significant impact on oxide erosion, and copper dishing is in proportion to dummy size. We also demonstrate that cross shape dummy fill can have the best dishing performance at the same density.展开更多
The newly identified Jinlin crater in southern China lies on a hillside covered by a thick granite weathering crust.It appears as a slightly elliptical bowl-shaped depression with a diameter of 820-900 m.The structure...The newly identified Jinlin crater in southern China lies on a hillside covered by a thick granite weathering crust.It appears as a slightly elliptical bowl-shaped depression with a diameter of 820-900 m.The structure is a tilted impact crater,showing a maximum rim height difference of about 200 m and an apparent depth of 90 m.The crater rim is composed mainly of granite weathered soil and a small amount of granite fragments,while the bottom of the crater is filled with the same mixture of granite weathered soil and granite fragments.Planar deformation features in quartz grains from the rock fragments of the crater provide decisive evidence for its impact origin.The impact event is inferred to have taken place during the Holocene.展开更多
Sodium layered oxides stand out as one of the most promising cathodes for sodium-ion batteries due to their high energy density,elemental abundance,and scalability.However,their practical applications are restricted b...Sodium layered oxides stand out as one of the most promising cathodes for sodium-ion batteries due to their high energy density,elemental abundance,and scalability.However,their practical applications are restricted by interplanar gliding,cation migration,and the formation of intragranular microcracks,which collectively lead to rapid structural degradation and capacity loss.Herein,we rationally design an ultrastable O3-type Na_(0.94)Ca_(0.03)Ni_(1/3)Fe_(1/3)Mn_(1/3)O_(2) cathode,in which Ca^(2+)cations act as pillars within the NaO_(2)slabs,suppressing the irreversible phase transitions and Na/TM cation migration commonly observed in layered oxides.Multiscale in situ and ex situ techniques,combined with post-mortem analysis,reveal that the Ca-pillared pinning effect not only effectively suppresses the interplanar gliding and stress accumulation within the crystal phase but also restrains Na/TM cation migration and surface reconstruction in near-surface regions.Benefiting from the combined effects of structural stabilization,the Ca-pillared cathode exhibits a superior cycling stability,retaining 81.6%of its capacity after 1000 cycles at 2 C within the voltage range of 2.0-4.0 V,along with significantly enhanced wide-temperature(from-40 to 80℃)performance.This work highlights another critical role of Ca pillars in suppressing cation migration and surface structural degradation beyond preventing adverse interplanar gliding,offering valuable insights for designing long-life and wide-temperature layered oxide cathodes.展开更多
An injective k-edge coloring of a graph G is k-edge coloringκof G such thatκ(e1)≠κ(e3)for any three consecutive edges ei,e2 and e3 of a path or a triangle.The injective chromatic index of G,denoted by x'i(G),i...An injective k-edge coloring of a graph G is k-edge coloringκof G such thatκ(e1)≠κ(e3)for any three consecutive edges ei,e2 and e3 of a path or a triangle.The injective chromatic index of G,denoted by x'i(G),is the smallest integer k such that G has an injective k-edge coloring.In this paper,we prove that x'i(G)≤9 if G is a planar graph with maximum degreeΔ≤4,girth g≥6 and without intersecting 6-cycles.展开更多
Energetic materials face critical challenges in balancing energy density and safety,driving the development of low-sensitivity high-energy materials.Though vital for modern defense and civilian applications,low-sensit...Energetic materials face critical challenges in balancing energy density and safety,driving the development of low-sensitivity high-energy materials.Though vital for modern defense and civilian applications,low-sensitivity high-energy materials remain scarce,with 1,3,5-trinitro-2,4,6-triaminobenzene as the only deployed example.Planar lamellar energetic crystals,which utilize weak interlamellarπ-πstacking for mechanical energy dissipation,have shown significant promise.However,their rational design is constrained by insufficient understanding of intermolecular interaction synergy.This review synthesizes the structural features of planar lamellar energetic crystals,emphasizing three core elements:the single-atomic-thickness planar stacking architecture,the"strong intralamellar and weak interlamellar interaction"paradigm(key to balancing energy density and safety for low-sensitivity high-energy materials,LSHEMs),and the role of molecular planarity in reducing shear slip barriers.It categorizes design strategies into two frameworks:H–bonding dominated(single-component:cross-shaped assembly,strong H–bonding in high symmetric molecules;multi-component methods:tenon-and-mortise,acceptor-donor separation)and other intermolecular interactions(e.g.,π-πstacking-drivenπ-π2max model,π-hole recognition).Case studies in single/multi-component crystals confirm that these strategies tune interaction synergy to achieve target packing motifs.The review highlights that interaction engineering is pivotal for PLEC design,offering a targeted theoretical framework for rational development of LSHEMs(to address the scarcity of practical LSHEMs)and guiding future crystal engineering for energy-safety balanced systems.展开更多
High-Mach-number plasma jets have been extensively investigated in both astrophysical and laboratory contexts.In this work,we revisit the framework of magnetohydrodynamic(MHD)theory and introduce a new analytical appr...High-Mach-number plasma jets have been extensively investigated in both astrophysical and laboratory contexts.In this work,we revisit the framework of magnetohydrodynamic(MHD)theory and introduce a new analytical approach for examining plasma jets generated by intense laser-plasma interactions.Specifically,we reformulate the fundamental MHD equations to elucidate the governing factors of local plasma density evolution.Furthermore,MHD simulations of laser irradiation on planar targets demonstrate that impact pressure plays a dominant role in the propagation of high-Mach-number plasma jets.In addition,a pronounced dependence on the atomic number is identified:higher-Z materials amplify the impact pressure,suggesting that metallicity exerts a significant influence on the morphology and dynamics of astrophysical jets.展开更多
A t-tone coloring of a graph assigns t distinct colors to each vertex with vertices at distance d having fewer than d colors in common.The t-tone chromatic number of a graph is the smallest number of colors used in al...A t-tone coloring of a graph assigns t distinct colors to each vertex with vertices at distance d having fewer than d colors in common.The t-tone chromatic number of a graph is the smallest number of colors used in all t-tone colorings of that graph.In this article,we study t-tone coloring of some finite planar lattices and obtain exact formulas for their t-tone chromatic number.展开更多
Accurately estimating depth from underwater monocular images is essential for the target tracking task of unmanned underwater vehicles.This work proposes a method based on the Lpg-Lap Unet architecture.First,the Unet ...Accurately estimating depth from underwater monocular images is essential for the target tracking task of unmanned underwater vehicles.This work proposes a method based on the Lpg-Lap Unet architecture.First,the Unet architecture integrates Laplacian pyramid depth residuals and Sobel operators to improve the boundary details in depth images,which may suffer from the feature loss caused by upsampling and the blurriness of underwater images.Multiscale local planar guidance layers then fully exploit the intermediate depth features,and a comprehensive loss function ensures robustness and accuracy.Experimental results on benchmarks demonstrate the effectiveness of Lpg-Lap Unet and its superior performance over state-of-the-art models.An underwater target tracking system is then designed to further validate its real-time capabilities in the AirSim simulation platform.展开更多
The pursuit of heat-resistant energetic materials(HREMs)with thermal stability beyond 450℃ presents a significant challenge that has yet to be achieved.In this work,we develop an innovative electronic delocalization ...The pursuit of heat-resistant energetic materials(HREMs)with thermal stability beyond 450℃ presents a significant challenge that has yet to be achieved.In this work,we develop an innovative electronic delocalization strategy to design and synthesize a planar dizwitterionic diamino-bistriazolotetrazine,designated as TYX-1.The unique structural feature of TYX-1,including a nitrogen-rich fused ring system,planar conformation,and dizwitterionic configuration,combined with its hydrogen-bonded organic framework(HOF)structure,confer exceptional thermal stability(The onset temperature is 428℃,and the peak temperature is 473℃),high density(1.84 g/cm^(3)),and remarkable detonation performance(detonation velocity:8616 m/s).Furthermore,TYX-1 exhibits an impressive insensitivity(impact sensitivity>40 J;friction sensitivity>360 N),surpassing all previously reported HREMs.Theoretical calculations and single-crystal clearly indicate that the delocalizedπelectrons within the dizwitterionic bistriazolotetrazine rings and the HOF structure of TYX-1 are pivotal in ensuring its high thermal stability and high energy density.The discovery of TYX-1 marks a significant advancement in the field of HREMs and is anticipated to catalyze substantial progress in various high-temperature applications reliant on energetic materials.展开更多
By integrating self-localization,environment mapping,and dynamic object tracking into a unified framework,visual simultaneous localization and mapping with multiple object tracking(SLAMMOT)enhances decision-making and...By integrating self-localization,environment mapping,and dynamic object tracking into a unified framework,visual simultaneous localization and mapping with multiple object tracking(SLAMMOT)enhances decision-making and interaction capabilities in applications such as autonomous driving,robotic navigation,and augmented reality.While numerous outstanding visual SLAMMOT methods have been proposed,the majority rely only on point features,overlooking the abundant and stable planar features in artificial objects that can provide valuable constraints.To address this limitation,we propose OP(object planar)-SLAM,an RGB-D SLAMMOT system that leverages planar features to improve object pose estimation and reconstruction accuracy.Specifically,we introduce an accurate object planar feature extraction and association method using normal images,alongside a novel object bundle adjustment framework that incorporates planar constraints for enhanced optimization.The proposed system is evaluated on both synthetic and public real-world datasets,including Oxford multimotion dataset(OMD)and KITTI tracking dataset.Especially on the OMD,where planar features are prominent,our method improves object pose estimation accuracy by approximately 60%.Extensive experiments demonstrate its effectiveness in enhancing object pose estimation and reconstruction,achieving notable performance compared with existing methods.Furthermore,OP-SLAM runs in real time,making it suitable for practical robots and augmented reality applications.展开更多
Liquid crystal Pacharatnam-Berry phase optical elements(PBOEs)have found promising applications in augmented reality and virtual reality because of their slim formfactor,lightweight,and high optical efficiency.However...Liquid crystal Pacharatnam-Berry phase optical elements(PBOEs)have found promising applications in augmented reality and virtual reality because of their slim formfactor,lightweight,and high optical efficiency.However,chromatic aberration remains a serious longstanding problem for diffractive optics,hindering their broader adoption.To overcome the chromatic aberrations for red,green and blue(RGB)light sources,in this paper,we propose a counterintuitive multi-twist structure to achieve narrowband PBOEs without crosstalk,which plays a vital role to eliminate the chromatic aberration.The performance of our designed and fabricated narrowband Pacharatnam-Berry lenses(PBLs)aligns well with our simulation results.Furthermore,in a feasibility demonstration experiment using a laser projector,our proposed PBL system indeed exhibits a diminished chromatic aberration as compared to a broadband PBL.Additionally,polarization raytracing is implemented to demonstrate the versatility of the multi-twist structure for designing any RGB wavelengths with high contrast ratios.This analysis explores the feasibility of using RGB laser lines and quantum dot light-emitting diodes.Overall,our approach enables high optical efficiency,low fabrication complexity,and high degree of design freedom to accommodate any liquid crystal material and RGB light sources,holding immense potential for widespread applications of achromatic PBOEs.展开更多
A novel substrate integrated microstrip to ultra-thin cavity filter transition operating in the W-band is proposed in this letter.The structure is a new method of connecting microstrip circuits and waveguide filters,a...A novel substrate integrated microstrip to ultra-thin cavity filter transition operating in the W-band is proposed in this letter.The structure is a new method of connecting microstrip circuits and waveguide filters,and this new structure enables a planar integrated transition from microstrip lines to ultra-thin cavity filters,thereby reducing the size of the transition structure and achieving miniaturization.The structure includes a conventional tapered microstrip transition structure,which guides the electromagnetic field from the microstrip line to the reduced-height dielectric-filled waveguide,and an air-filled matching cavity which is placed between the dielectric-filled waveguide and the ultra-thin cavity filter.The heights of the microstrip line,the dielectric-filled waveguide and the ultra-thin cavity filter are the same,enabling seamless integration within a planar radio-frequency(RF)circuit.To facilitate testing,mature finline transition structures are integrated at both ends of the microstrip line during fabrications.The simulation results of the fabricated microstrip to ultra-thin cavity filter transition with the finline transition structure,with a passband of 91.5-96.5 GHz,has an insertion loss of less than 1.9 dB and a return loss lower than-20 dB.And the whole structure has also been measured which achieves an insertion loss less than 2.6 dB and a return loss lower than-15 dB within the filter's passband,including the additional insertion loss introduced by the finline transitions.Finally,a W-band compact up-conversion module is designed,and the test results show that after using the proposed structure,the module achieves 95 dBc suppression of the 84 GHz local oscillator.It is also demonstrated that the structure proposed in this letter achieves miniaturization of the system integration without compromising the filter performance.展开更多
A graph G is called d-degenerate if every subgraph of G has a vertex of degree at most d.It was known that planar graphs are 5-degenerate and every planar graph without k-cycles for some prescribed k∈{3,5,6}is 3-dege...A graph G is called d-degenerate if every subgraph of G has a vertex of degree at most d.It was known that planar graphs are 5-degenerate and every planar graph without k-cycles for some prescribed k∈{3,5,6}is 3-degenerate.In this paper,we show that if G is a planar graph without kites and 9-or 10-cycles,then G is 3-degenerate,hence 4-choosable and list vertex 2-arborable.展开更多
基金supported by NSFC(No.12201202)NSF of Hunan Province(No.2023JJ30180)NSFC(No.12471022)。
文摘The Pfaffian property of graphs is of fundamental importance in graph theory,as it precisely characterizes those graphs for which the number of perfect matchings can be computed in polynomial time with respect to the number of edges.The study of Pfaffian graphs originated from the enumeration of perfect matching in planar graphs.References[5,6,8]demonstrated that every planar graph is Pfaffian.Therefore,the Pfaffian property and planarity of graphs play a vital role in modern matching theory.This paper contributes a complete characterization of the Pfaffian property and planarity of connected Cayley graphs over the dicyclic group T_(4n) of order 4n(n≥3),shows that the Cayley graph Cay(T_(4n),S)is Pfaffian if and only if n is odd and S={a^(k_(1)),a^(2n−k_(1)),ba^(k_(2)),ba^(n+k_(2))},where 1≤k_(1)≤n−1,0≤k_(2)≤n−1 and(k_(1),n)=1,and furthermore,shows that Cay(T4n,S)is never planar.
文摘The movement of interacting faults within the Earth’s crust during earthquakes may cause significant structural damage.Large earthquake fault surfaces are often planar or a combination of several planar fault segments.This study analyses the interaction between a non-planar and a planar fault,where the faults are inclined,buried,creeping and strike-slip in nature.The non-planar fault is infinite and formed by two interconnected planar segments,while the planar fault is finite.The present analysis adduces the movement of interacting faults in a composite structure comprised of an elastic layer nested on a visco-elastic substrate of Maxwell medium.The significant effect of various affecting parameters viz.inclination of the faults,velocity of the fault movement,depth of the faults from the free surface,distance between the faults and the non-planarity of the fault has been discussed and also compared.The amount of stress and surface shear strain is restored after the creeping movement.The graphical representation of the effect of non-planarity of the fault on stress-strain accumulation has been established.Analytical solutions are obtained using Laplace transform and Green’s function techniques,supported by numerical simulations.The obtained results provide insights into fault interaction process and have important implications for assessing seismic hazard potential in viscoelastic media.The study of such earthquake fault dynamical models may give some ideas about the nature of stress-strain accumulation or release in the system and help us to observe the mechanism of lithosphere-asthenosphere boundary.
基金the National Key R&D Program of China(2018YFB1500101)National Basic Research Program of China(No.2015CB932200)CAS-Iranian Vice Presidency for Science and Technology Joint Research Project(No.116134KYSB20160130).
文摘A new benzothiadiazole-based D-A-D hole transport material(DTBT)has been designed and synthesized with a more planar structure by introducing of thiophene bridges.The results indicate a lower band gap and quite higher hole mobility for the DTBT.Furthermore,the enhancement in molecular planarity with simple thiophene unit increases the hole mobility of DTBT(8.77×10^-4cm^2 V^-1s^-1)by about 40%.And when DTBT is used as hole transport material in perovskite solar cells,the photoelectric conversion efficiency of the corresponding dopant-free devices is also significantly improved compared with that of the conventional BT model molecule without thiophene.In terms of device stability,DTBT-based devices show a favorable long-term stability,which keep 83%initial efficiency after 15 days.Therefore,the introducing of thiophene bridges in D-A-D typed HTMs can improve the molecular planarity effectively,thereby increasing the hole mobility and improving device performance.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11575072 and 11475074)the Fundamental Research Funds for the Central Universities(Grant No.lzujbky-2017-172)
文摘We study the effects of the planarity and heterogeneity of networks on evolutionary two-player symmetric games by considering four different kinds of networks, including two types of heterogeneous networks: the weighted planar stochastic lattice(a planar scale-free network) and the random uncorrelated scale-free network with the same degree distribution as the weighted planar stochastic lattice; and two types of homogeneous networks: the hexagonal lattice and the random regular network with the same degree k_0= 6 as the hexagonal lattice. Using extensive computer simulations, we found that both the planarity and heterogeneity of the network have a significant influence on the evolution of cooperation, either promotion or inhibition, depending not only on the specific kind of game(the Harmony, Snowdrift, Stag Hunt or Prisoner's Dilemma games), but also on the update rule(the Fermi, replicator or unconditional imitation rules).
基金supported financially by the National Key R&D Program of China(grant no.2022YFE0130600)the National Natural Science Foundation of China(grant nos.22075001 and 92156019)+2 种基金the King Abdullah University of Science and Technology(KAUST)Competitive Research Grants under award no.ORA-CRG10-2021-4668support from the KAUST Office of Sponsored Research under award no.OSA-CRG2021-4668supported by the High-performance Computing Platform of Peking University.
文摘To date,extensive efforts have been devoted to designing new conjugated polymers with long alkyl or ethylene glycol sidechains.However,these sidechains are insulators,limiting further performance enhancement in doped conjugated polymers.Moreover,the most widely used chlorinated solvents are toxic,limiting the practical applications of many conjugated polymers.Here,we report a water/alcohol processable n-type conjugated polymer P(Py2FT),featuring side chain-free cationic backbones.P(Py2FT)exhibits a high n-type electrical conductivity of up to 28.1 S cm^(−1)and a high thermoelectric power factor of up to 28.7μWm^(−1)K^(−2),comparable to some conventional n-type conjugated polymers reported recently.More importantly,cationic polymers display tight molecular packings and interesting enhanced backbone planarity after n-doping,which,we envision,provides a new research direction to address the sidechain issue in conventional conjugated polymers.Our work demonstrates that sidechain-free cationic polymers have great potential for green-solvent-processed heavily doped organic electronics.
基金This work was financially supported by the National Natural Science Foundation of China(Nos.52130309 and 51903014)Beijing Natural Science Foundation(No.2202043)Changzhou Sci&Tech Program(No.CJ20210041).
文摘Self-assembly of dyes has become a flexible strategy to modulate their photophysical properties.H-aggregates show great potential to increase heat generation,while the precise designing of H-aggregates as efficient photothermal agents is still challenging.Herein,a quinoline cyanine(QCy)is developed for constructing stable H-aggregated nanoparticles(NPs)to significantly enhance photostability and photothermal conversion efficiency(PCE).With symmetrical rigid planar quinoline structures,QCy has a small and symmetrical dihedral angle(11.9°),which ensures excellent molecular planarity.In aqueous solution,the planar QCy can form closeπ–πmolecular stacking,and fast self-assemble into stable H-aggregates even at low concentrations(1×10−7 M).QCy H-aggregates are sphere-like NPs(QCy NPs)with an average diameter of 120 nm and exhibit high stability.H-aggregation of QCy significantly enhances PCE from 20.1%(non-H-aggregated QCy)to 63.8%(QCy NPs).In addition,the positive charge of quaternarized quinoline provides mitochondrial anchoring ability,which further enhances the photothermal effect.With high PCE and tumor accumulation,QCy NPs in low-doses have been successfully used in photoacoustic imaging-guided tumor photothermal therapy.
基金Project supported by the National Major Science and Technology Special Project of China(No.2008ZX01035-001-08)
文摘With the use of a chemical-mechanical polishing （CMP） simulator verified by testing data from a foundry, the effect of dummy fill characteristics, such as fill size, fill density and fill shape, on CMP planarity is analyzed. The results indicate that dummy density has a significant impact on oxide erosion, and copper dishing is in proportion to dummy size. We also demonstrate that cross shape dummy fill can have the best dishing performance at the same density.
基金financial support from Shanghai Key Laboratory Novel Extreme Condition Materials,China(Grant No.22dz2260800)the Shanghai Science and Technology Committee,China(Grant No.22JC1410300).
文摘The newly identified Jinlin crater in southern China lies on a hillside covered by a thick granite weathering crust.It appears as a slightly elliptical bowl-shaped depression with a diameter of 820-900 m.The structure is a tilted impact crater,showing a maximum rim height difference of about 200 m and an apparent depth of 90 m.The crater rim is composed mainly of granite weathered soil and a small amount of granite fragments,while the bottom of the crater is filled with the same mixture of granite weathered soil and granite fragments.Planar deformation features in quartz grains from the rock fragments of the crater provide decisive evidence for its impact origin.The impact event is inferred to have taken place during the Holocene.
基金supported by the National Key R&D Program of China(2023YFB2406000)the National Natural Science Foundation of China(22479057,52172201,51732005)。
文摘Sodium layered oxides stand out as one of the most promising cathodes for sodium-ion batteries due to their high energy density,elemental abundance,and scalability.However,their practical applications are restricted by interplanar gliding,cation migration,and the formation of intragranular microcracks,which collectively lead to rapid structural degradation and capacity loss.Herein,we rationally design an ultrastable O3-type Na_(0.94)Ca_(0.03)Ni_(1/3)Fe_(1/3)Mn_(1/3)O_(2) cathode,in which Ca^(2+)cations act as pillars within the NaO_(2)slabs,suppressing the irreversible phase transitions and Na/TM cation migration commonly observed in layered oxides.Multiscale in situ and ex situ techniques,combined with post-mortem analysis,reveal that the Ca-pillared pinning effect not only effectively suppresses the interplanar gliding and stress accumulation within the crystal phase but also restrains Na/TM cation migration and surface reconstruction in near-surface regions.Benefiting from the combined effects of structural stabilization,the Ca-pillared cathode exhibits a superior cycling stability,retaining 81.6%of its capacity after 1000 cycles at 2 C within the voltage range of 2.0-4.0 V,along with significantly enhanced wide-temperature(from-40 to 80℃)performance.This work highlights another critical role of Ca pillars in suppressing cation migration and surface structural degradation beyond preventing adverse interplanar gliding,offering valuable insights for designing long-life and wide-temperature layered oxide cathodes.
基金Supported by the National Natural Science Foundation of China(Grant Nos.12071265,12001481)the Natural Science Foundation of Shandong Province(Grant No.ZR2021MA103)the Youth Innovation Team Project of Shandong Province Universities(Grant No.2024KJG078).
文摘An injective k-edge coloring of a graph G is k-edge coloringκof G such thatκ(e1)≠κ(e3)for any three consecutive edges ei,e2 and e3 of a path or a triangle.The injective chromatic index of G,denoted by x'i(G),is the smallest integer k such that G has an injective k-edge coloring.In this paper,we prove that x'i(G)≤9 if G is a planar graph with maximum degreeΔ≤4,girth g≥6 and without intersecting 6-cycles.
基金supported by the National Natural Science Foundation of China under Grant No.22505100.
文摘Energetic materials face critical challenges in balancing energy density and safety,driving the development of low-sensitivity high-energy materials.Though vital for modern defense and civilian applications,low-sensitivity high-energy materials remain scarce,with 1,3,5-trinitro-2,4,6-triaminobenzene as the only deployed example.Planar lamellar energetic crystals,which utilize weak interlamellarπ-πstacking for mechanical energy dissipation,have shown significant promise.However,their rational design is constrained by insufficient understanding of intermolecular interaction synergy.This review synthesizes the structural features of planar lamellar energetic crystals,emphasizing three core elements:the single-atomic-thickness planar stacking architecture,the"strong intralamellar and weak interlamellar interaction"paradigm(key to balancing energy density and safety for low-sensitivity high-energy materials,LSHEMs),and the role of molecular planarity in reducing shear slip barriers.It categorizes design strategies into two frameworks:H–bonding dominated(single-component:cross-shaped assembly,strong H–bonding in high symmetric molecules;multi-component methods:tenon-and-mortise,acceptor-donor separation)and other intermolecular interactions(e.g.,π-πstacking-drivenπ-π2max model,π-hole recognition).Case studies in single/multi-component crystals confirm that these strategies tune interaction synergy to achieve target packing motifs.The review highlights that interaction engineering is pivotal for PLEC design,offering a targeted theoretical framework for rational development of LSHEMs(to address the scarcity of practical LSHEMs)and guiding future crystal engineering for energy-safety balanced systems.
基金supported by the National Natural Science Foundation of China(Grant Nos.12325305,12175018,and 12135001)the National Key RD Program of China(Grant Nos.2022YFA1603200 and 2022YFA1603203).
文摘High-Mach-number plasma jets have been extensively investigated in both astrophysical and laboratory contexts.In this work,we revisit the framework of magnetohydrodynamic(MHD)theory and introduce a new analytical approach for examining plasma jets generated by intense laser-plasma interactions.Specifically,we reformulate the fundamental MHD equations to elucidate the governing factors of local plasma density evolution.Furthermore,MHD simulations of laser irradiation on planar targets demonstrate that impact pressure plays a dominant role in the propagation of high-Mach-number plasma jets.In addition,a pronounced dependence on the atomic number is identified:higher-Z materials amplify the impact pressure,suggesting that metallicity exerts a significant influence on the morphology and dynamics of astrophysical jets.
基金Supported by the National Natural Science Foundation of China(Grant No.12271210)the Scientific Research Foundation of Jimei University(Grant No.Q202201).
文摘A t-tone coloring of a graph assigns t distinct colors to each vertex with vertices at distance d having fewer than d colors in common.The t-tone chromatic number of a graph is the smallest number of colors used in all t-tone colorings of that graph.In this article,we study t-tone coloring of some finite planar lattices and obtain exact formulas for their t-tone chromatic number.
基金partially supported by the Natural Science Foundation of Shandong Province,China(No.ZR2023ME009)the National Natural Science Foundation of China(No.51909252)。
文摘Accurately estimating depth from underwater monocular images is essential for the target tracking task of unmanned underwater vehicles.This work proposes a method based on the Lpg-Lap Unet architecture.First,the Unet architecture integrates Laplacian pyramid depth residuals and Sobel operators to improve the boundary details in depth images,which may suffer from the feature loss caused by upsampling and the blurriness of underwater images.Multiscale local planar guidance layers then fully exploit the intermediate depth features,and a comprehensive loss function ensures robustness and accuracy.Experimental results on benchmarks demonstrate the effectiveness of Lpg-Lap Unet and its superior performance over state-of-the-art models.An underwater target tracking system is then designed to further validate its real-time capabilities in the AirSim simulation platform.
基金supported by the National Natural Science Foundation of China(Grant Nos.22105156,22175139,22505195,22171136,22405207 and 22302156)the China National Science Fund for Distinguished Young Scholars(Grant No.22325504)。
文摘The pursuit of heat-resistant energetic materials(HREMs)with thermal stability beyond 450℃ presents a significant challenge that has yet to be achieved.In this work,we develop an innovative electronic delocalization strategy to design and synthesize a planar dizwitterionic diamino-bistriazolotetrazine,designated as TYX-1.The unique structural feature of TYX-1,including a nitrogen-rich fused ring system,planar conformation,and dizwitterionic configuration,combined with its hydrogen-bonded organic framework(HOF)structure,confer exceptional thermal stability(The onset temperature is 428℃,and the peak temperature is 473℃),high density(1.84 g/cm^(3)),and remarkable detonation performance(detonation velocity:8616 m/s).Furthermore,TYX-1 exhibits an impressive insensitivity(impact sensitivity>40 J;friction sensitivity>360 N),surpassing all previously reported HREMs.Theoretical calculations and single-crystal clearly indicate that the delocalizedπelectrons within the dizwitterionic bistriazolotetrazine rings and the HOF structure of TYX-1 are pivotal in ensuring its high thermal stability and high energy density.The discovery of TYX-1 marks a significant advancement in the field of HREMs and is anticipated to catalyze substantial progress in various high-temperature applications reliant on energetic materials.
基金Supported by Major Science and Technology Project of Hubei Province(2022AAA009)。
文摘By integrating self-localization,environment mapping,and dynamic object tracking into a unified framework,visual simultaneous localization and mapping with multiple object tracking(SLAMMOT)enhances decision-making and interaction capabilities in applications such as autonomous driving,robotic navigation,and augmented reality.While numerous outstanding visual SLAMMOT methods have been proposed,the majority rely only on point features,overlooking the abundant and stable planar features in artificial objects that can provide valuable constraints.To address this limitation,we propose OP(object planar)-SLAM,an RGB-D SLAMMOT system that leverages planar features to improve object pose estimation and reconstruction accuracy.Specifically,we introduce an accurate object planar feature extraction and association method using normal images,alongside a novel object bundle adjustment framework that incorporates planar constraints for enhanced optimization.The proposed system is evaluated on both synthetic and public real-world datasets,including Oxford multimotion dataset(OMD)and KITTI tracking dataset.Especially on the OMD,where planar features are prominent,our method improves object pose estimation accuracy by approximately 60%.Extensive experiments demonstrate its effectiveness in enhancing object pose estimation and reconstruction,achieving notable performance compared with existing methods.Furthermore,OP-SLAM runs in real time,making it suitable for practical robots and augmented reality applications.
基金supported by the National Scientific Foundation of China Nos.11431010 and 11571329“the Fundamental Research Funds for the Central Universities.”。
文摘We give a combinatorial characterization of upward planar graphs in terms of upward planar orders,which are special linear extensions of edge posets.
基金supports from the National Key Research and Development Program of China(2023YFB2806803)the National Natural Science Foundation of China(62075127).
文摘Liquid crystal Pacharatnam-Berry phase optical elements(PBOEs)have found promising applications in augmented reality and virtual reality because of their slim formfactor,lightweight,and high optical efficiency.However,chromatic aberration remains a serious longstanding problem for diffractive optics,hindering their broader adoption.To overcome the chromatic aberrations for red,green and blue(RGB)light sources,in this paper,we propose a counterintuitive multi-twist structure to achieve narrowband PBOEs without crosstalk,which plays a vital role to eliminate the chromatic aberration.The performance of our designed and fabricated narrowband Pacharatnam-Berry lenses(PBLs)aligns well with our simulation results.Furthermore,in a feasibility demonstration experiment using a laser projector,our proposed PBL system indeed exhibits a diminished chromatic aberration as compared to a broadband PBL.Additionally,polarization raytracing is implemented to demonstrate the versatility of the multi-twist structure for designing any RGB wavelengths with high contrast ratios.This analysis explores the feasibility of using RGB laser lines and quantum dot light-emitting diodes.Overall,our approach enables high optical efficiency,low fabrication complexity,and high degree of design freedom to accommodate any liquid crystal material and RGB light sources,holding immense potential for widespread applications of achromatic PBOEs.
基金Supported by the Fundamental Research Funds for the Central Universities(ZYGX2021J008)。
文摘A novel substrate integrated microstrip to ultra-thin cavity filter transition operating in the W-band is proposed in this letter.The structure is a new method of connecting microstrip circuits and waveguide filters,and this new structure enables a planar integrated transition from microstrip lines to ultra-thin cavity filters,thereby reducing the size of the transition structure and achieving miniaturization.The structure includes a conventional tapered microstrip transition structure,which guides the electromagnetic field from the microstrip line to the reduced-height dielectric-filled waveguide,and an air-filled matching cavity which is placed between the dielectric-filled waveguide and the ultra-thin cavity filter.The heights of the microstrip line,the dielectric-filled waveguide and the ultra-thin cavity filter are the same,enabling seamless integration within a planar radio-frequency(RF)circuit.To facilitate testing,mature finline transition structures are integrated at both ends of the microstrip line during fabrications.The simulation results of the fabricated microstrip to ultra-thin cavity filter transition with the finline transition structure,with a passband of 91.5-96.5 GHz,has an insertion loss of less than 1.9 dB and a return loss lower than-20 dB.And the whole structure has also been measured which achieves an insertion loss less than 2.6 dB and a return loss lower than-15 dB within the filter's passband,including the additional insertion loss introduced by the finline transitions.Finally,a W-band compact up-conversion module is designed,and the test results show that after using the proposed structure,the module achieves 95 dBc suppression of the 84 GHz local oscillator.It is also demonstrated that the structure proposed in this letter achieves miniaturization of the system integration without compromising the filter performance.
文摘A graph G is called d-degenerate if every subgraph of G has a vertex of degree at most d.It was known that planar graphs are 5-degenerate and every planar graph without k-cycles for some prescribed k∈{3,5,6}is 3-degenerate.In this paper,we show that if G is a planar graph without kites and 9-or 10-cycles,then G is 3-degenerate,hence 4-choosable and list vertex 2-arborable.
