To acquire a knowledge of the stress-strain state in the process of mining beforehand, a numerical method was used to simulate the stoping process of access mechanized panel mining in No. 3 ore-body of Tonglushan mine...To acquire a knowledge of the stress-strain state in the process of mining beforehand, a numerical method was used to simulate the stoping process of access mechanized panel mining in No. 3 ore-body of Tonglushan mine; and for the sake of obtaining better stability, the optimal panel dimension and access stoping sequence were researched. The results show that the integral stability of the mechanized panel of No. 3 ore-body is passable in the process of winning at full level height; the stability of panel tends to be worse gradually with continuous increasing of panel width; and the better width of access panel in No.3 ore-body is less than 52 m. It is indicated that 3D elasto-plastic finite element method can make a satisfactory study of numerical simulation on the panel stability and its structural dimension in the test for the upward access mechanized-panel mining. The results of the theoretical calculation and analysis accord with the actual situation from the field ground pressure monitoring.展开更多
In order to know about the essence of service employees' innovation behavior, the service employees' innovation behavior scale based on their unique characteristics is designed. Data were collected from high-s...In order to know about the essence of service employees' innovation behavior, the service employees' innovation behavior scale based on their unique characteristics is designed. Data were collected from high-star hospitalities. Through the issuance and the collection of questionnaires, the scale is verified to have good reliability and validity by SPSS software analysis. Meanwhile,the structural equation model( SEM) is suited for testing structural dimensions of service employees' innovation behavior. The results showed that service employees' innovation behavior could be decomposed into a four-dimensional structure,namely innovation orientation, ideas generation, innovation implementation and innovation practice. In addition,there are significant differences in service employees' innovation behavior about subjects' gender,position,education background and years of working.展开更多
Inspired by the abundant structural diversity and potential applications of Sb-based oxysulfides,two new compounds with the same stoichiometry,Ae_(2)Sb_(2)O_(2)S_(3) (Ae=Ca,Ba),were successfully synthesized via solid ...Inspired by the abundant structural diversity and potential applications of Sb-based oxysulfides,two new compounds with the same stoichiometry,Ae_(2)Sb_(2)O_(2)S_(3) (Ae=Ca,Ba),were successfully synthesized via solid state reactions. Both crystallize in the C2/c space group (no. 15) of a monoclinic system,however,possess different structural dimensions induced by different sizes of template alkaline-earth ions. Ca_(2)Sb_(2)O_(2)S_(3) is composed of one-dimensional anionic [Sb_(2)O_(2)S_(3)]^(4-) chains isolated by Ca^(2+) ions,while Ba_(2)Sb_(2)O_(2)S_(3) consists of zero-dimensional anionic [Sb_(2)O_(2)S_(3)]^(4-) clusters separated by Ba^(2+) ions. Higher structural dimension endows the 1D Ca_(2)Sb_(2)O_(2)S_(3) with a higher melting point (m.p.=720℃) and a narrower band gap (E_g=2.36 eV),compared with the m.p.=692℃ and E_g=2.78 eV of Ba_(2)Sb_(2)O_(2)S_(3). Both exhibit interesting photoluminescence properties with multi-emission characteristics. DFT calculations reveal that the band edges of Ae_(2)Sb_(2)O_(2)S_(3) are mainly composed of Sb−S bond orbitals,while O 2p orbitals also contribute to the valence band maximum of Ba_(2)Sb_(2)O_(2)S_(3).展开更多
A novel three-dimensional porous dysprosium coordination polymer{[Dy_(2)L_(2)(bpdo)_(2)(H_(2)O)(CH_(3)OH)]·2ClO4·2CH_(3)CN}_(n)(1)has been successfully assembled by combining a superparamagnetic building blo...A novel three-dimensional porous dysprosium coordination polymer{[Dy_(2)L_(2)(bpdo)_(2)(H_(2)O)(CH_(3)OH)]·2ClO4·2CH_(3)CN}_(n)(1)has been successfully assembled by combining a superparamagnetic building block of[DyLCl(CH_(3)OH)]_(2)with the organic ligand 4,4’-bipyridine-N,N’-dioxide(bpdo)(H_(2)L=N’-(_(2)-hydroxybenzylidene)picolinohydrazide).展开更多
In this study,melamine and cyanuric acid were used as precursors to form supramolecular crystals via hydrogen-bond-assisted self-assembly followed by hydrothermal treatment.Subsequent high-temperature calcination yiel...In this study,melamine and cyanuric acid were used as precursors to form supramolecular crystals via hydrogen-bond-assisted self-assembly followed by hydrothermal treatment.Subsequent high-temperature calcination yielded a novel brush-like three-dimensional carbon nitride.The brush-like 3D architecture was found to expose more accessible active sites,markedly accelerate electron transfer,and suppress the recombination of photogenerated charge carriers.The resulting superoxide(O_(2)^(-·))and hydroxyl(·OH)radicals generated via electron reduction were identified as the key reactive species in the photocatalytic process.Moreover,the surface of the brush-like structure is enriched with nitrogen vacancies,which enhance the catalyst’s ability to harvest visible light.The photocatalytic performance of the brush-like CNS-650 catalyst was evaluated for rhodamine B(RhB)degradation.Under red-light irradiation(660 nm),its degradation rate was 7.4 times higher than that of bulk CN.This work provides valuable insights into the design and application of efficient metal-free 3D photocatalysts.展开更多
Reticulated polyurethane was chosen as the preceramic material for preparing the porous preform using the replication process. The immersing and sintering processes were each performed twice for fabricating a high-por...Reticulated polyurethane was chosen as the preceramic material for preparing the porous preform using the replication process. The immersing and sintering processes were each performed twice for fabricating a high-porosity and super-strong skeleton. The aluminum magnesium matrix composites reinforced with three-dimensional network structure were prepared using the infiltration technique by pressure assisting and vacuum driving. Light interfacial reactions have played a profitable role in most of the ceramic-metal systems. The metal matrix composites interpenetrated with the ceramic phase have a higher wear resistance than the metal matrix phase. The volume fraction of ceramic reinforcement has a significant effect on the abrasive wear, and the wear rate can be decreased with the increase of the volume fraction of reinforcement.展开更多
Gaseous detonation propagating in a toroidal chamber was numerically studied for hydrogen/oxygen/nitrogen mixtures. The numerical method used is based on the three-dimensional Euler equations with detailed finiterate ...Gaseous detonation propagating in a toroidal chamber was numerically studied for hydrogen/oxygen/nitrogen mixtures. The numerical method used is based on the three-dimensional Euler equations with detailed finiterate chemistry. The results show that the calculated streak picture is in qualitative agreement with the picture recorded by a high speed streak camera from published literature. The three-dimensional flow field induced by a continuously rotating detonation was visualized and distinctive features of the rotating detonations were clearly depicted. Owing to the unconfined character of detonation wavelet, a deficit of detonation parameters was observed. Due to the effects of wall geometries, the strength of the outside detonation front is stronger than that of the inside portion. The detonation thus propagates with a constant circular velocity. Numerical simulation also shows three-dimensional rotating detonation structures, which display specific feature of the detonation- shock combined wave. Discrete burning gas pockets are formed due to instability of the discontinuity. It is believed that the present study could give an insight into the interest- ing properties of the continuously rotating detonation, and is thus beneficial to the design of continuous detonation propulsion systems.展开更多
Neuronal ensemble activity codes working memory.In this work,we developed a neuronal ensemble sparse coding method,which can effectively reduce the dimension of the neuronal activity and express neural coding.Multicha...Neuronal ensemble activity codes working memory.In this work,we developed a neuronal ensemble sparse coding method,which can effectively reduce the dimension of the neuronal activity and express neural coding.Multichannel spike trains were recorded in rat prefrontal cortex during a work memory task in Y-maze.As discretesignals,spikes were transferred into cont inuous signals by estinating entropy.Then the normalized continuous signals were decomposed via non-negative sparse met hod.The non-negative components were extracted to reconstruct a low-dimensional ensemble,while none of the feature components were missed.The results showed that,for well-trained rats,neuronal ensemble activities in the prefrontal cortex changed dynamically during the.working memory task.And the neuronal ensemble is more explicit via using non-negative sparse coding.Our results indicate that the neuronal ensemblesparse coding method can effectively reduce the dimnension of neuronal activity and it is a useful tool to express neural coding.展开更多
A novel three dimensional network complex polymer [Cu_4(oxen)_2(N_3)_3]_n(ClO_4)_n·2nH_2O, where oxen is N,N' -bis(2-aminoethyl)oxamide dianion, has been synthesized. It crystallizes in triclinic system, spac...A novel three dimensional network complex polymer [Cu_4(oxen)_2(N_3)_3]_n(ClO_4)_n·2nH_2O, where oxen is N,N' -bis(2-aminoethyl)oxamide dianion, has been synthesized. It crystallizes in triclinic system, space group P, with a=11.486(2), b=11.706(3), c=12.291(3) , α=77.42(2), β=67.59(2), γ=77.96(2)°, and z=2. The least-square refinements converged at R=0.047, with 3416 observed unique reflections. The complex has a pronounced three-dimensional character and can be viewed as the tetranuclear asymmetric repeating units through inversion and translation operations to extend a three-dimensional network. The structure of Cu_4 asymmetric unit consists of two square planar and two square pyramidal Cu central atoms linked by both azide ligands in end-on and end-to-end bonding modes, and oxamidate bridge in trans conformation.展开更多
The integrability of a （2＋1）-dimensional super nonlinear evolution equation is analyzed in the framework of the fermionie covariant prolongation structure theory. We construct the prolongation structure of the mult...The integrability of a （2＋1）-dimensional super nonlinear evolution equation is analyzed in the framework of the fermionie covariant prolongation structure theory. We construct the prolongation structure of the multidimen- sional super integrable equation and investigate its Lax representation. Furthermore, the Backlund transformation is presented and we derive a solution to the super integrable equation.展开更多
Non-stoichiometric carbides have been proven to be effective electromagnetic wave(EMW)absorbing materials.In this study,phase and morphology of XZnC(X=Fe/Co/Cu)loaded on a three dimensional(3D)network structure melami...Non-stoichiometric carbides have been proven to be effective electromagnetic wave(EMW)absorbing materials.In this study,phase and morphology of XZnC(X=Fe/Co/Cu)loaded on a three dimensional(3D)network structure melamine sponge(MS)carbon composites were investigated through vacuum filtration followed by calcination.The FeZnC/CoZnC/CuZnC with carbon nanotubes(CNTs)were uniformly dispersed on the surface of melamine sponge carbon skeleton and Co-containing sample exhibits the highest CNTs concentration.The minimum reflection loss(RL_(min))of the CoZnC/MS composite(m_(composite):m_(paraffin)=1:1,m represents mass)reached-33.60 dB,and the effective absorption bandwidth(EAB)reached 9.60 GHz.The outstanding electromagnetic wave absorption(EMWA)properties of the CoZnC/MS composite can be attributed to its unique hollow structure,which leads to multiple reflections and scattering.The formed conductive network improves dielectric and conductive loss.The incorporation of Co enhances the magnetic loss capability and optimizes interfacial polarization and dipole polarization.By simultaneously improving dielectric and magnetic losses,ex-cellent impedance matching performance is achieved.The clarification of element replacement in XZnC/MS composites provides an effi-cient design perspective for high-performance non-stoichiometric carbide EMW absorbers.展开更多
Motivated by the success of methylammonium lead iodide,substantial efforts have been made to search for moisture-and air-stable metal halide perovskites(MHPs)for various optoelectronic applications.Lowering the struct...Motivated by the success of methylammonium lead iodide,substantial efforts have been made to search for moisture-and air-stable metal halide perovskites(MHPs)for various optoelectronic applications.Lowering the structural dimensionality in 2D and quasi-2D MHPs greatly increases the stability,but the simultaneously lowered electronic dimensionality leads to less efficient and large anisotropic charge carrier separation and transport.Herein,we report the construction and characterization of three 3D MHP analogs APb_(2)I_(6)(A=linear alkyl-diammonium cation)displaying balanced high stability and isotropic photoresponse.Single-crystal-based devices exhibit on/off ratios of photocurrent higher than 1.0×10^(3) in all three crystallographic directions and ultra-long device stability(>12 months)at 40%relative humidity.The enhanced stability and quasi-isotropic photoresponse are ascribed to the specific choice of the cations and the genuine 3D electronic dimensionality.This type of 3D MPH analog is expected to be a promising candidate for fabricating high-performance optoelectronic devices.展开更多
Two novel molybdenyl carbonates named Cs_(2)MoO_(3)(CO_(3))and Cs_(3)MoO_(4)(HCO_(3))have been synthesized using a facile solvent evaporation method.Centrosymmetric Cs_(2)MoO_(3)(CO_(3))features one-dimensional chains...Two novel molybdenyl carbonates named Cs_(2)MoO_(3)(CO_(3))and Cs_(3)MoO_(4)(HCO_(3))have been synthesized using a facile solvent evaporation method.Centrosymmetric Cs_(2)MoO_(3)(CO_(3))features one-dimensional chains composed of MoO_(6)octahedra and CO_(3)groups,while noncentrosymmetric Cs_(3)MoO_(4)(HCO_(3))displays a zero dimensional framework constructed with dispersive MoO_(4)tetrahedra and HCO_(3)groups.Remarkably,although these two compounds have the same chemical composition,their band gaps differ as large as 1.04 eV,which is 3.38 eV for Cs_(2)MoO_(3)(CO_(3))and 4.42 eV for Cs_(3)MoO_(4)(HCO_(3)).The molecular orbital hybridization between MoO_(6)and CO_(3)in 1D chains narrows the band gap of Cs_(2)MoO_(3)(CO_(3)),which is further supported by the electron density difference map through theoretical calculations.展开更多
Two low-dimensional Cu(I)boron imidazolate frameworks(BIFs),[CuBH(bim)_(3)]_(n)(BIF-40;bim=benzimidazolate)and[CuBH(im)_(3)]_(n)(BIF-6,im=imidazolate),have been synthesized and both of them display unique mechanochrom...Two low-dimensional Cu(I)boron imidazolate frameworks(BIFs),[CuBH(bim)_(3)]_(n)(BIF-40;bim=benzimidazolate)and[CuBH(im)_(3)]_(n)(BIF-6,im=imidazolate),have been synthesized and both of them display unique mechanochromism.In addition,BIF-40 showed reducing activity due to the rich B–H bonds in the structure,and it was employed to load AuPd bimetal nanoparticles through a one-step process for further catalysis.The corresponding mechanism involving a grinding process between chains or layers is discussed in detail.This work not only provides compelling evidence for designing and applying coordination polymers as mechanochromic materials,but also develops an eco-friendly strategy for loading bimetallic NPs into BIFs.展开更多
One-dimensional nanocrystalline semiconductors have been comprehensively studied because of their fascinating properties and practical applications in various fields.However,exploring a facile preparation technique an...One-dimensional nanocrystalline semiconductors have been comprehensively studied because of their fascinating properties and practical applications in various fields.However,exploring a facile preparation technique and improving and optimizing current performance remain big challenges.In this work,zinc oxide(ZnO)nanocrystals with different one-dimensional structures,ranging from multi-armed nanorods and rough nanorods to nanowires,have been successfully synthesized via a facile solvothermal strategy in a hexalene glycol-H_(2)O reaction system.The variations in the crystal phase and the structure of the ZnO nanocrystals are investigated in detail by using powder X-ray diffraction,scanning electron microscopy,and transmission electron microscopy.The effects of different ZnO structures on the catalytic ability were evaluated through the photodegradation of an antibiotic,ciprofloxacin,and an organic dye,Rhodamine B,under simulated solar light irradiation.The photocatalysis system constructed from the multi-armed ZnO nanorod photocatalyst shows superior efficiency compared to the ZnO nanorods and nanowires.This enhancement in the photocatalytic ability of the ZnO multi-armed nanorods compared to other nanostructures is attributed mainly to their unique structure,efficient electron-hole separation,and faster charge transport,on the basis of photoluminescence spectra,and photocurrent,and electrochemical impedance spectroscopy measurements.展开更多
Constructing one-dimensional(1D)hierarchical photocatalysts is deemed to be central to promoting photocatalytic capacity.In this paper,1D hierarchical structures composed of CdS nanosheets/nanoparticles on Ag nanowire...Constructing one-dimensional(1D)hierarchical photocatalysts is deemed to be central to promoting photocatalytic capacity.In this paper,1D hierarchical structures composed of CdS nanosheets/nanoparticles on Ag nanowires(denoted as 1D Ag@CdS core-shell hierarchical hetero-nanowires)have been fabricated via a wet-chemistry approach at low temperature.The optimization of the synthetic parameters indicates that the amounts of Cd(NO_(3))_(2)·4H_(2)O and thiourea play important roles in the construction of the 1D hierarchical structures.The as-prepared 1D hierarchical Ag@CdS core-shell hetero-nanowires exhibit efficient photocatalytic performance in both methyl orange(MO)degradation(degrade 96% of MO within 240 min)and hydrogen generation(73.5μmol h^(-1))from water splitting due to the unique hybrid nanoarchitecture.It is expected that this Ag@CdS hierarchical nanostructure could have potential in solar energy conversion and this fabrication technique could be used as a reference to design other 1D metal@semiconductor core-shell heteronanowires.展开更多
Reuse of solid industrial wastes is an effective approach to develop low-carbon construction materials. This paper examines how two materials, steel slag（ST） and granulated blast-furnace slag（SL） impact the mechan...Reuse of solid industrial wastes is an effective approach to develop low-carbon construction materials. This paper examines how two materials, steel slag（ST） and granulated blast-furnace slag（SL） impact the mechanical performance and pore structure of cement-based systems. Analysis was done on the variations of the porosity, pore size, and pore volume distribution with the curing age and replacement content, and the fractal dimensions of pore surfaces. The results suggested that systems with both supplementary materials had lower early strengths than pure cement, but could generally surpass pure cement paste after 90 d; higher SL content was particularly helpful for boosting the late strengths. The addition of ST increased the porosities and mean pore sizes at each age, and both increased with ST content; SL was helpful for decreasing the system＇s late porosity（especially harmless pores below 20 nm）; The lowest porosity and mean pore size were obtained with 20% SL. Both systems had notably fractal characteristics on pore surfaces, with ST systems showing the highest dimensions at 10% ST, and SL systems at 20% SL. Compressive strength displayed a significant linear increase with fractal dimension.展开更多
Recently,two-dimensional MXene materials have attracted numerous attention in electromagnetic wave shielding/absorption.Hybridizing magnetic materials and constructing multi-dimensional structures in MXene is highly b...Recently,two-dimensional MXene materials have attracted numerous attention in electromagnetic wave shielding/absorption.Hybridizing magnetic materials and constructing multi-dimensional structures in MXene is highly beneficial to improve electromagnetic wave absorption properties.Herein,we demonstrate a strategy for in situ growing 0 D CoNi nanoalloy-encapsulated 1 D N-doped carbon nanotubes on a2 D Ti_(3)C_(2)T_(x)MXene sheet through an electrostatic assembly process followed by a high-temperature pyrolysis process.The resultant 201-structured MXene-CoNi@N-doped carbon nanotube(MXene-CoNi@NCNT)composites displayed high surface areas(55.6-103.7 m^(2)/g),moderate magnetism(19.8-24.6 emu/g),and excellent thermal oxidation stabilities(≥ 307℃).In addition,the unique 2 D/0 D/1 D architectures entrusted the composites with abundant interfaces,various defects,and numerous nitrogen dopants.Taking advantage of the special 201 structure and the existence of both magnetic and dielectric loss,the MXeneCoNi@NCNT composite showed great impedance matching and strong attenuation performance.A strong reflection loss of-55.3 dB was achieved when the coating thickness was 2.1 mm,and a wide effective absorption bandwidth of 4.3 GHz was achieved at a thickness of 1.5 mm,much superior to that of similar absorbers.This work demonstrates a novel strategy for designing electromagnetic wave absorbers with magnetic and dielectric losses accompanied by multiple dimensional structures.展开更多
The structural feature shown on a remote sensing image is a synthetic result ofcombination of the deformations produced during the entire geological history of an area.Therefore, the respective tectonic stress field o...The structural feature shown on a remote sensing image is a synthetic result ofcombination of the deformations produced during the entire geological history of an area.Therefore, the respective tectonic stress field of each of the different stages in the complexdeformation of an area can be reconstructed in three steps: (1) geological structures formed atdifferent times are distinguished in remote sensing image interpretation; (2) structuraldeformation fields at different stages are determined by analyzing relationships betweenmicrostructures (joints and fractures) and the related structures (folds and faults); and (3)tectonic stress fields at different stages are respectively recovered through a study of the featuresof structural deformation fields in different periods. Circular structures and related circlular and radial joints are correlated in space to con-cealed structural rises. The authors propose a new method for establishing a natural model ofthe concealed structural rises and calculating the tectonic stress field by using quantitative dataof the remote sensing information of circular structures and related linear structures.展开更多
基金Project(2001BA901A09) supported by the Key Program of the 10th Five year Plan of China
文摘To acquire a knowledge of the stress-strain state in the process of mining beforehand, a numerical method was used to simulate the stoping process of access mechanized panel mining in No. 3 ore-body of Tonglushan mine; and for the sake of obtaining better stability, the optimal panel dimension and access stoping sequence were researched. The results show that the integral stability of the mechanized panel of No. 3 ore-body is passable in the process of winning at full level height; the stability of panel tends to be worse gradually with continuous increasing of panel width; and the better width of access panel in No.3 ore-body is less than 52 m. It is indicated that 3D elasto-plastic finite element method can make a satisfactory study of numerical simulation on the panel stability and its structural dimension in the test for the upward access mechanized-panel mining. The results of the theoretical calculation and analysis accord with the actual situation from the field ground pressure monitoring.
基金Shanghai University of Engineering Science's Research Cultivation Fund Project,China(No.A25001201194)National Natural Science Foundation,China(No.71301100)+1 种基金the Fundamental Research Funds for the Central Universities,China(No.JB-SK1204)China Postdoctoral Science Foundation(No.2014M561655)
文摘In order to know about the essence of service employees' innovation behavior, the service employees' innovation behavior scale based on their unique characteristics is designed. Data were collected from high-star hospitalities. Through the issuance and the collection of questionnaires, the scale is verified to have good reliability and validity by SPSS software analysis. Meanwhile,the structural equation model( SEM) is suited for testing structural dimensions of service employees' innovation behavior. The results showed that service employees' innovation behavior could be decomposed into a four-dimensional structure,namely innovation orientation, ideas generation, innovation implementation and innovation practice. In addition,there are significant differences in service employees' innovation behavior about subjects' gender,position,education background and years of working.
基金supported by the National Natural Science Foundation of China(Grant 21871008,22005006,and 22001263)the China Postdoctoral Science Foundation(Grant 2019M660298 and 2020T130009).
文摘Inspired by the abundant structural diversity and potential applications of Sb-based oxysulfides,two new compounds with the same stoichiometry,Ae_(2)Sb_(2)O_(2)S_(3) (Ae=Ca,Ba),were successfully synthesized via solid state reactions. Both crystallize in the C2/c space group (no. 15) of a monoclinic system,however,possess different structural dimensions induced by different sizes of template alkaline-earth ions. Ca_(2)Sb_(2)O_(2)S_(3) is composed of one-dimensional anionic [Sb_(2)O_(2)S_(3)]^(4-) chains isolated by Ca^(2+) ions,while Ba_(2)Sb_(2)O_(2)S_(3) consists of zero-dimensional anionic [Sb_(2)O_(2)S_(3)]^(4-) clusters separated by Ba^(2+) ions. Higher structural dimension endows the 1D Ca_(2)Sb_(2)O_(2)S_(3) with a higher melting point (m.p.=720℃) and a narrower band gap (E_g=2.36 eV),compared with the m.p.=692℃ and E_g=2.78 eV of Ba_(2)Sb_(2)O_(2)S_(3). Both exhibit interesting photoluminescence properties with multi-emission characteristics. DFT calculations reveal that the band edges of Ae_(2)Sb_(2)O_(2)S_(3) are mainly composed of Sb−S bond orbitals,while O 2p orbitals also contribute to the valence band maximum of Ba_(2)Sb_(2)O_(2)S_(3).
基金supported by the National Natural Science Foundation of China(No 21671024)National Key Basic Research Program of China(2013CB933402).
文摘A novel three-dimensional porous dysprosium coordination polymer{[Dy_(2)L_(2)(bpdo)_(2)(H_(2)O)(CH_(3)OH)]·2ClO4·2CH_(3)CN}_(n)(1)has been successfully assembled by combining a superparamagnetic building block of[DyLCl(CH_(3)OH)]_(2)with the organic ligand 4,4’-bipyridine-N,N’-dioxide(bpdo)(H_(2)L=N’-(_(2)-hydroxybenzylidene)picolinohydrazide).
基金Supported by the National Natural Science Foundation of China(Grant 22578376,52374283)the Natural Science Foundation of Jiangsu Province(Grant BK20240332)。
文摘In this study,melamine and cyanuric acid were used as precursors to form supramolecular crystals via hydrogen-bond-assisted self-assembly followed by hydrothermal treatment.Subsequent high-temperature calcination yielded a novel brush-like three-dimensional carbon nitride.The brush-like 3D architecture was found to expose more accessible active sites,markedly accelerate electron transfer,and suppress the recombination of photogenerated charge carriers.The resulting superoxide(O_(2)^(-·))and hydroxyl(·OH)radicals generated via electron reduction were identified as the key reactive species in the photocatalytic process.Moreover,the surface of the brush-like structure is enriched with nitrogen vacancies,which enhance the catalyst’s ability to harvest visible light.The photocatalytic performance of the brush-like CNS-650 catalyst was evaluated for rhodamine B(RhB)degradation.Under red-light irradiation(660 nm),its degradation rate was 7.4 times higher than that of bulk CN.This work provides valuable insights into the design and application of efficient metal-free 3D photocatalysts.
基金This work was financially supported by the Natural Science Foundation of Shandong Province, China (Y2006F03).
文摘Reticulated polyurethane was chosen as the preceramic material for preparing the porous preform using the replication process. The immersing and sintering processes were each performed twice for fabricating a high-porosity and super-strong skeleton. The aluminum magnesium matrix composites reinforced with three-dimensional network structure were prepared using the infiltration technique by pressure assisting and vacuum driving. Light interfacial reactions have played a profitable role in most of the ceramic-metal systems. The metal matrix composites interpenetrated with the ceramic phase have a higher wear resistance than the metal matrix phase. The volume fraction of ceramic reinforcement has a significant effect on the abrasive wear, and the wear rate can be decreased with the increase of the volume fraction of reinforcement.
基金supported by the National Natural Science Foundation of China (10872096)the Open Fund of State Key Laboratory of Explosion Science and Technology, Beijing University of Science and Technology (KFJJ09-13)
文摘Gaseous detonation propagating in a toroidal chamber was numerically studied for hydrogen/oxygen/nitrogen mixtures. The numerical method used is based on the three-dimensional Euler equations with detailed finiterate chemistry. The results show that the calculated streak picture is in qualitative agreement with the picture recorded by a high speed streak camera from published literature. The three-dimensional flow field induced by a continuously rotating detonation was visualized and distinctive features of the rotating detonations were clearly depicted. Owing to the unconfined character of detonation wavelet, a deficit of detonation parameters was observed. Due to the effects of wall geometries, the strength of the outside detonation front is stronger than that of the inside portion. The detonation thus propagates with a constant circular velocity. Numerical simulation also shows three-dimensional rotating detonation structures, which display specific feature of the detonation- shock combined wave. Discrete burning gas pockets are formed due to instability of the discontinuity. It is believed that the present study could give an insight into the interest- ing properties of the continuously rotating detonation, and is thus beneficial to the design of continuous detonation propulsion systems.
基金supported by the National Natural Science Foundation of China(No.61074131,91132722)the Doctoral Fund of the Ministry of Education of China(20101202110007).
文摘Neuronal ensemble activity codes working memory.In this work,we developed a neuronal ensemble sparse coding method,which can effectively reduce the dimension of the neuronal activity and express neural coding.Multichannel spike trains were recorded in rat prefrontal cortex during a work memory task in Y-maze.As discretesignals,spikes were transferred into cont inuous signals by estinating entropy.Then the normalized continuous signals were decomposed via non-negative sparse met hod.The non-negative components were extracted to reconstruct a low-dimensional ensemble,while none of the feature components were missed.The results showed that,for well-trained rats,neuronal ensemble activities in the prefrontal cortex changed dynamically during the.working memory task.And the neuronal ensemble is more explicit via using non-negative sparse coding.Our results indicate that the neuronal ensemblesparse coding method can effectively reduce the dimnension of neuronal activity and it is a useful tool to express neural coding.
文摘A novel three dimensional network complex polymer [Cu_4(oxen)_2(N_3)_3]_n(ClO_4)_n·2nH_2O, where oxen is N,N' -bis(2-aminoethyl)oxamide dianion, has been synthesized. It crystallizes in triclinic system, space group P, with a=11.486(2), b=11.706(3), c=12.291(3) , α=77.42(2), β=67.59(2), γ=77.96(2)°, and z=2. The least-square refinements converged at R=0.047, with 3416 observed unique reflections. The complex has a pronounced three-dimensional character and can be viewed as the tetranuclear asymmetric repeating units through inversion and translation operations to extend a three-dimensional network. The structure of Cu_4 asymmetric unit consists of two square planar and two square pyramidal Cu central atoms linked by both azide ligands in end-on and end-to-end bonding modes, and oxamidate bridge in trans conformation.
基金Supported by the National Natural Science Foundation of China under Grant Nos 11605096,11547101 and 11601247
文摘The integrability of a （2＋1）-dimensional super nonlinear evolution equation is analyzed in the framework of the fermionie covariant prolongation structure theory. We construct the prolongation structure of the multidimen- sional super integrable equation and investigate its Lax representation. Furthermore, the Backlund transformation is presented and we derive a solution to the super integrable equation.
基金supported by the National Natural Science Foundation of China(Nos.52101274,52377026 and 52472131)Taishan Scholars and Young Experts Program of Shandong Province,China(No.tsqn202103057)+4 种基金Natural Science Foundation of Shandong Province,China(Nos.ZR2020QE011 and ZR2022ME089)the Qingchuang Talents Induction Program of Shandong Higher Education Institution,China(Research and Innovation Team of Structural-Functional Polymer Composites)Youth Top Talent Foundation of Yantai University,China(No.2219008)Graduate Innovation Foundation of Yantai University,China(No.GIFYTU2240)College Student Innovation and Entrepreneurship Training Program Project,China(No.202311066088).
文摘Non-stoichiometric carbides have been proven to be effective electromagnetic wave(EMW)absorbing materials.In this study,phase and morphology of XZnC(X=Fe/Co/Cu)loaded on a three dimensional(3D)network structure melamine sponge(MS)carbon composites were investigated through vacuum filtration followed by calcination.The FeZnC/CoZnC/CuZnC with carbon nanotubes(CNTs)were uniformly dispersed on the surface of melamine sponge carbon skeleton and Co-containing sample exhibits the highest CNTs concentration.The minimum reflection loss(RL_(min))of the CoZnC/MS composite(m_(composite):m_(paraffin)=1:1,m represents mass)reached-33.60 dB,and the effective absorption bandwidth(EAB)reached 9.60 GHz.The outstanding electromagnetic wave absorption(EMWA)properties of the CoZnC/MS composite can be attributed to its unique hollow structure,which leads to multiple reflections and scattering.The formed conductive network improves dielectric and conductive loss.The incorporation of Co enhances the magnetic loss capability and optimizes interfacial polarization and dipole polarization.By simultaneously improving dielectric and magnetic losses,ex-cellent impedance matching performance is achieved.The clarification of element replacement in XZnC/MS composites provides an effi-cient design perspective for high-performance non-stoichiometric carbide EMW absorbers.
基金financially supported by the National Natural Science Foundation of China(Grants 21991144 and 21875035)。
文摘Motivated by the success of methylammonium lead iodide,substantial efforts have been made to search for moisture-and air-stable metal halide perovskites(MHPs)for various optoelectronic applications.Lowering the structural dimensionality in 2D and quasi-2D MHPs greatly increases the stability,but the simultaneously lowered electronic dimensionality leads to less efficient and large anisotropic charge carrier separation and transport.Herein,we report the construction and characterization of three 3D MHP analogs APb_(2)I_(6)(A=linear alkyl-diammonium cation)displaying balanced high stability and isotropic photoresponse.Single-crystal-based devices exhibit on/off ratios of photocurrent higher than 1.0×10^(3) in all three crystallographic directions and ultra-long device stability(>12 months)at 40%relative humidity.The enhanced stability and quasi-isotropic photoresponse are ascribed to the specific choice of the cations and the genuine 3D electronic dimensionality.This type of 3D MPH analog is expected to be a promising candidate for fabricating high-performance optoelectronic devices.
基金supported by the National Natural Science Foundation of China(no.21971171,21875146,22071158,22122106).
文摘Two novel molybdenyl carbonates named Cs_(2)MoO_(3)(CO_(3))and Cs_(3)MoO_(4)(HCO_(3))have been synthesized using a facile solvent evaporation method.Centrosymmetric Cs_(2)MoO_(3)(CO_(3))features one-dimensional chains composed of MoO_(6)octahedra and CO_(3)groups,while noncentrosymmetric Cs_(3)MoO_(4)(HCO_(3))displays a zero dimensional framework constructed with dispersive MoO_(4)tetrahedra and HCO_(3)groups.Remarkably,although these two compounds have the same chemical composition,their band gaps differ as large as 1.04 eV,which is 3.38 eV for Cs_(2)MoO_(3)(CO_(3))and 4.42 eV for Cs_(3)MoO_(4)(HCO_(3)).The molecular orbital hybridization between MoO_(6)and CO_(3)in 1D chains narrows the band gap of Cs_(2)MoO_(3)(CO_(3)),which is further supported by the electron density difference map through theoretical calculations.
基金support of this work by the 973 program(2012CB821705)NSFC(21221001,21203196,21425102)CAS(XDA07070200).
文摘Two low-dimensional Cu(I)boron imidazolate frameworks(BIFs),[CuBH(bim)_(3)]_(n)(BIF-40;bim=benzimidazolate)and[CuBH(im)_(3)]_(n)(BIF-6,im=imidazolate),have been synthesized and both of them display unique mechanochromism.In addition,BIF-40 showed reducing activity due to the rich B–H bonds in the structure,and it was employed to load AuPd bimetal nanoparticles through a one-step process for further catalysis.The corresponding mechanism involving a grinding process between chains or layers is discussed in detail.This work not only provides compelling evidence for designing and applying coordination polymers as mechanochromic materials,but also develops an eco-friendly strategy for loading bimetallic NPs into BIFs.
基金the supporting of Hubei Key Laboratory of Biomass Fibers and Eco-dyeing&Finishing(STRZ2017019)the supporting of the National Natural Science Foundation of China(21501137)Support from the Australian Research Council(ARC)through an ARC Discovery project(DP160102627)is gratefully acknowledged.
文摘One-dimensional nanocrystalline semiconductors have been comprehensively studied because of their fascinating properties and practical applications in various fields.However,exploring a facile preparation technique and improving and optimizing current performance remain big challenges.In this work,zinc oxide(ZnO)nanocrystals with different one-dimensional structures,ranging from multi-armed nanorods and rough nanorods to nanowires,have been successfully synthesized via a facile solvothermal strategy in a hexalene glycol-H_(2)O reaction system.The variations in the crystal phase and the structure of the ZnO nanocrystals are investigated in detail by using powder X-ray diffraction,scanning electron microscopy,and transmission electron microscopy.The effects of different ZnO structures on the catalytic ability were evaluated through the photodegradation of an antibiotic,ciprofloxacin,and an organic dye,Rhodamine B,under simulated solar light irradiation.The photocatalysis system constructed from the multi-armed ZnO nanorod photocatalyst shows superior efficiency compared to the ZnO nanorods and nanowires.This enhancement in the photocatalytic ability of the ZnO multi-armed nanorods compared to other nanostructures is attributed mainly to their unique structure,efficient electron-hole separation,and faster charge transport,on the basis of photoluminescence spectra,and photocurrent,and electrochemical impedance spectroscopy measurements.
基金the Australian Research Council(ARC)through the Discovery Projects DP 130102274 and DP130102699 and from ISEM at UOWJiangsu Specially Appointed Professorship+2 种基金the Program of Jiangsu Innovative and Entrepreneurial Talentsthe use of the facilities in the UOW Electron Microscopy Centre,with particular thanks to David R.G.Mitchellsupport from the Jiangsu Provincial Key Laboratory of Radiation Medicine and Protection and the Priority Academic Development Program of Jiangsu Higher Education Institutions(PAPD).
文摘Constructing one-dimensional(1D)hierarchical photocatalysts is deemed to be central to promoting photocatalytic capacity.In this paper,1D hierarchical structures composed of CdS nanosheets/nanoparticles on Ag nanowires(denoted as 1D Ag@CdS core-shell hierarchical hetero-nanowires)have been fabricated via a wet-chemistry approach at low temperature.The optimization of the synthetic parameters indicates that the amounts of Cd(NO_(3))_(2)·4H_(2)O and thiourea play important roles in the construction of the 1D hierarchical structures.The as-prepared 1D hierarchical Ag@CdS core-shell hetero-nanowires exhibit efficient photocatalytic performance in both methyl orange(MO)degradation(degrade 96% of MO within 240 min)and hydrogen generation(73.5μmol h^(-1))from water splitting due to the unique hybrid nanoarchitecture.It is expected that this Ag@CdS hierarchical nanostructure could have potential in solar energy conversion and this fabrication technique could be used as a reference to design other 1D metal@semiconductor core-shell heteronanowires.
基金Funded by the Technology Innovation Major Project of Hubei Province(No.2017ACA178)
文摘Reuse of solid industrial wastes is an effective approach to develop low-carbon construction materials. This paper examines how two materials, steel slag（ST） and granulated blast-furnace slag（SL） impact the mechanical performance and pore structure of cement-based systems. Analysis was done on the variations of the porosity, pore size, and pore volume distribution with the curing age and replacement content, and the fractal dimensions of pore surfaces. The results suggested that systems with both supplementary materials had lower early strengths than pure cement, but could generally surpass pure cement paste after 90 d; higher SL content was particularly helpful for boosting the late strengths. The addition of ST increased the porosities and mean pore sizes at each age, and both increased with ST content; SL was helpful for decreasing the system＇s late porosity（especially harmless pores below 20 nm）; The lowest porosity and mean pore size were obtained with 20% SL. Both systems had notably fractal characteristics on pore surfaces, with ST systems showing the highest dimensions at 10% ST, and SL systems at 20% SL. Compressive strength displayed a significant linear increase with fractal dimension.
基金financially supported by the National Natural Science Foundation of China (Nos.52122302,51991c351,and 51790504)the Fundamental Research Funds for the Central Universities+1 种基金the Young Elite Scientists Sponsorship Program by CASTFinancial support by the 111 Project (B20001)。
文摘Recently,two-dimensional MXene materials have attracted numerous attention in electromagnetic wave shielding/absorption.Hybridizing magnetic materials and constructing multi-dimensional structures in MXene is highly beneficial to improve electromagnetic wave absorption properties.Herein,we demonstrate a strategy for in situ growing 0 D CoNi nanoalloy-encapsulated 1 D N-doped carbon nanotubes on a2 D Ti_(3)C_(2)T_(x)MXene sheet through an electrostatic assembly process followed by a high-temperature pyrolysis process.The resultant 201-structured MXene-CoNi@N-doped carbon nanotube(MXene-CoNi@NCNT)composites displayed high surface areas(55.6-103.7 m^(2)/g),moderate magnetism(19.8-24.6 emu/g),and excellent thermal oxidation stabilities(≥ 307℃).In addition,the unique 2 D/0 D/1 D architectures entrusted the composites with abundant interfaces,various defects,and numerous nitrogen dopants.Taking advantage of the special 201 structure and the existence of both magnetic and dielectric loss,the MXeneCoNi@NCNT composite showed great impedance matching and strong attenuation performance.A strong reflection loss of-55.3 dB was achieved when the coating thickness was 2.1 mm,and a wide effective absorption bandwidth of 4.3 GHz was achieved at a thickness of 1.5 mm,much superior to that of similar absorbers.This work demonstrates a novel strategy for designing electromagnetic wave absorbers with magnetic and dielectric losses accompanied by multiple dimensional structures.
基金This study was sponsored by The Open Research Laboratory of Quantitative Prediction,Exploration and Assessment of Mineral Resources,MGMR,China.
文摘The structural feature shown on a remote sensing image is a synthetic result ofcombination of the deformations produced during the entire geological history of an area.Therefore, the respective tectonic stress field of each of the different stages in the complexdeformation of an area can be reconstructed in three steps: (1) geological structures formed atdifferent times are distinguished in remote sensing image interpretation; (2) structuraldeformation fields at different stages are determined by analyzing relationships betweenmicrostructures (joints and fractures) and the related structures (folds and faults); and (3)tectonic stress fields at different stages are respectively recovered through a study of the featuresof structural deformation fields in different periods. Circular structures and related circlular and radial joints are correlated in space to con-cealed structural rises. The authors propose a new method for establishing a natural model ofthe concealed structural rises and calculating the tectonic stress field by using quantitative dataof the remote sensing information of circular structures and related linear structures.
