The directional structure of Ni60/high-aluminum bronze composite coating was formed using induction remelting and forced cooling.The microstructural evolution and the characteristics of interface growth were studied.T...The directional structure of Ni60/high-aluminum bronze composite coating was formed using induction remelting and forced cooling.The microstructural evolution and the characteristics of interface growth were studied.The results showed that the remelted coating formed metallurgical bonding with the substrate.The micros tructures changed from plane crystal to dendrite,cellular dendrite,fine cellular dendrite,and then to dendrite again with the increase in the cooling rate.The crystal grew along the heat flow direction and had(111) and(200)preferred orientations when the cooling rate was 1.886 ml-min^(-1).mm^(-2).The plane crystal,dendrite and cellular dendrite were mainly composed of compounds and solid solutions with Ni,Fe and Cu,and they were surrounded by strengthening phases composed of Cr,C and B.The grain boundary of directional structure coatings showed the characteristic of regular eutectic growth,but grain boundary of remelted coating presented characteristic of divorced eutectic growth.The wear resistance of directional structure coatings is better than that of remelted coating.展开更多
Over the past two decades,superhydrophobic surfaces that are easily created have aroused considerable attention for their superior performances in various applications at room temperature.Nowadays,there is a growing d...Over the past two decades,superhydrophobic surfaces that are easily created have aroused considerable attention for their superior performances in various applications at room temperature.Nowadays,there is a growing demand in special fields for the development of surfaces that can resist wetting by high-temperature molten droplets(>1200°C)using facile design and fabrication strategies.Herein,bioinspired directional structures(BDSs)were prepared on Y2O3-stabilized ZrO2(YSZ)surfaces using femtosecond laser ablation.Benefiting from the anisotropic energy barriers,the BDSs featured with no additional modifiers showed a remarkable increase from 9.2°to 60°in the contact angle of CaO–MgO–Al2O3–SiO2(CMAS)melt and a 70.1%reduction in the spreading area of CMAS at 1250°C,compared with polished super-CMAS-melt-philic YSZ surfaces.Moreover,the BDSs demonstrated exceptional wetting inhibition even at 1400°C,with an increase from 3.3°to 31.3°in contact angle and a 67.9%decrease in spreading area.This work provides valuable insight and a facile preparation strategy for effectively inhibiting the wetting of molten droplets on super-melt-philic surfaces at extremely high temperatures.展开更多
The Ni60/15wt% Cu directional structure coating was prepared by the composite technology of flame spraying, induction remelting,and forced cooling, and the effect of Cu on the microstructure, phase, hardness, and wear...The Ni60/15wt% Cu directional structure coating was prepared by the composite technology of flame spraying, induction remelting,and forced cooling, and the effect of Cu on the microstructure, phase, hardness, and wear performance of Ni60 coatings was investigated. Results showed that Cu addition makes the microstructure of Ni60 directional structure coating more compact, and Cu is mainly enriched within the crystal grain, resulting in the formation of Cu_(3.8)Ni as the bonding phase. Compared with Ni60 directional structure coating, Ni60/Cu directional structure coating has a lower hardness, lower friction coefficient, and lower wear rate, which indicate that Cu can effectively enhance the antifriction performance of Ni60 directional structure coating.展开更多
The dissipation theory was introduced into the solidification area to describe the inherent laws of solidification from a new viewpoint. Discussion demonstrates that the solid / liquid interface in a directionally sol...The dissipation theory was introduced into the solidification area to describe the inherent laws of solidification from a new viewpoint. Discussion demonstrates that the solid / liquid interface in a directionally solidified alloy belongs to a kind of dissipation structure展开更多
UiO-66,reported in 2008,inspired the ongoing chemistry of group 4 metal–organic frameworks and it is still one of the most studied MOFs due to its exceptional stability.The tightness of their building blocks and bond...UiO-66,reported in 2008,inspired the ongoing chemistry of group 4 metal–organic frameworks and it is still one of the most studied MOFs due to its exceptional stability.The tightness of their building blocks and bond strength make it tough to access new topologies,unless the building blocks are changed or defect engineering is employed,which in turn lead to different nominal stoichiometries.However,well selected structure directing agents and harsh synthesis conditions allowed the isolation of the first polymorph of UiO-66,named EHU-30.Herein,we provide evidence for the generalization of the synthetic approach with four new EHU-30 isoreticular compounds,based on amino-functionalized linkers and zirconium and hafnium as metal centres:EHU-30-NH_(2)(M)and EHU-30-NHR(M)(M:Zr,Hf;R:2-carboxypropyl).The crystal structure analysis reveals that their framework is more porous than that of their polymorphic counterpart.Furthermore,due to the current relevance of MOFs in greenhouse gas capture and in water harvesting methodologies,we have explored CO_(2)and water vapour adsorption on the new polymorphic phases,by means of experimental and computational resources,and compared to the parent EHU-30.The amino functionalization makes the EHU-30 series more prone to CO_(2)and water vapour adsorption.Besides,the water adsorption isotherms show an interesting crossing sensitive to temperature,sorption cycles and functionalization of the linker,which has been attributed to a localized structural transformation from EHU-30 to UiO-66.Finally,time-of-flight(TOF)powder neutron diffraction experiments were also conducted to locate the preferred adsorption sites for water in functionalized and parent EHU-30 structures.展开更多
Advanced solid-state NMR techniques,including PT-J-HMQC ^(27)Al/^(31)P double-resonance NMR,2D ^(31)P and 1H DQ-SQ MAS NMR experiments,have been used to study the structure-directing effect in the crystallization of t...Advanced solid-state NMR techniques,including PT-J-HMQC ^(27)Al/^(31)P double-resonance NMR,2D ^(31)P and 1H DQ-SQ MAS NMR experiments,have been used to study the structure-directing effect in the crystallization of the molecular sieve AlPO_(4) -11 synthesized by a solvent-free method.展开更多
A one-pot strategy exploiting the structure directing effects of SeIV and TeIV heteroatoms has yielded the highest nuclearity noble metal containing polyoxometalates to date;including the palladium-rich selenotungstat...A one-pot strategy exploiting the structure directing effects of SeIV and TeIV heteroatoms has yielded the highest nuclearity noble metal containing polyoxometalates to date;including the palladium-rich selenotungstate isomers K_(28)[H_(12)Pd_(10)Se_(10)W_(52)O_(206)]·65H_(2)O(1)and K_(26)[H_(14)Pd_(10)Se_(10)W_(52)O_(2)06]·68H_(2)O(2),and the nanoscale tellurotungstate cluster Na_(40)[Pd_(6)Te_(19)W_(42)O_(190)]·76H_(2)O(3).These reaction systems exhibit remarkable structural flexibility and point to a new route towards the synthesis of complex heterometallic species,in which multiple lacunary polyoxometalate‘building blocks’have been assembled to trap a transient oxopalladate species suspected to play a role in the assembly of several common polyoxopalladates.Mass spectrometry has been applied to explore and compare the solution stability of compounds 1-3,demonstrating the markedly different properties of the SeIV and TeIV templated systems.Electrochemical analysis of 1 has been provided and is dominated by Pd redox processes,with reduction of the cluster resulting in electrodeposition of Pd metal and observation of the subsequent formation of PdO species,concurrent with previously reported oxopalladate containing species.展开更多
Zeolite synthesis in contemporary chemical industries is predominantly conducted using organic structure‐directing agents(OSDAs),which are chronically hazardous to humans and the environment.It is a growing trend to ...Zeolite synthesis in contemporary chemical industries is predominantly conducted using organic structure‐directing agents(OSDAs),which are chronically hazardous to humans and the environment.It is a growing trend to develop an eco‐friendly and nuisanceless OSDA for zeolite synthesis.Herein,choline is employed as a non‐toxic and green OSDA to synthesize high silica Y zeolite with SiO2/Al2O3 ratios of 6.5–6.8.The prepared Y zeolite samples exhibited outstanding(hydro)thermal stability at ultrahigh temperature owing to the higher SiO2/Al2O3 ratio.The XRF,SEM,29Si‐NMR and 13Na+results suggested that choline plays a structure‐directing role in the synthesis of Y zeolite,while the feed molar fraction of Na+is a crucial determinant for the framework SiO2/Al2O3 ratio and the crystal morphology.展开更多
To compensate for the imperfection of traditional bi-directional evolutionary structural optimization, material interpolation scheme and sensitivity filter functions are introduced. A suitable filter can overcome the ...To compensate for the imperfection of traditional bi-directional evolutionary structural optimization, material interpolation scheme and sensitivity filter functions are introduced. A suitable filter can overcome the checkerboard and mesh-dependency. And the historical information on accurate elemental sensitivity numbers are used to keep the objective function converging steadily. Apart from rational intervals of the relevant important parameters, the concept of distinguishing between active and non-active elements design is proposed, which can be widely used for improving the function and artistry of structures directly, especially for a one whose accurate size is not given. Furthermore, user-friendly software packages are developed to enhance its accessibility for practicing engineers and architects. And to reduce the time cost for large timeconsuming complex structure optimization, parallel computing is built-in in the MATLAB codes. The program is easy to use for engineers who may not be familiar with either FEA or structure optimization. And developers can make a deep research on the algorithm by changing the MATLAB codes. Several classical examples are given to show that the improved BESO method is superior for its handy and utility computer program software.展开更多
Nickel coated diamond composite powders were fabricated via a newly developed direct electrodeposition technique. The effects of activators on the coating of diamond were firstly investigated and diamond grinding whee...Nickel coated diamond composite powders were fabricated via a newly developed direct electrodeposition technique. The effects of activators on the coating of diamond were firstly investigated and diamond grinding wheels were then prepared from Ni-coated diamond composite powders with different activators. The microstructural characterizations of this composite powders were finally conducted by scanning electron microscopy, energy dispersive spectroscopy, and X-ray diffraction, and the mechanical and tribological properties of as-prepared diamond grinding wheels were also measured. There are changes in microstructures and properties of the composite powders with activators. The activator concentration also has an influence on the morphologies and phase structures of the Ni coating on diamond particles.The composite powders with more compact coating of nickel can be prepared by adding 1 g dm^（-3） or more AgNO_3 as an activator to electrodeposit nickel on diamond. The mechanical and tribological properties of diamond grinding wheels were significantly improved when the coating phase structure of Ni crystal grew with（111） plane orientation on the surface of diamond particles. The wheels made from nickel coated diamond composite powders possessed the advantages of easy preparation and outstanding tribological properties. Therefore, Ni coated diamond composite powders exhibit a great potential to be extensively applied in diamond cutting and grinding tools.展开更多
Curcurbit[n]uril(Q[n])-based supramolecular frameworks(QSFs) constructed from the outer surface interaction of Q[n]s(OSIQ) have the characteristic of simplicity,diversity and modulability.Their simplicity is reflected...Curcurbit[n]uril(Q[n])-based supramolecular frameworks(QSFs) constructed from the outer surface interaction of Q[n]s(OSIQ) have the characteristic of simplicity,diversity and modulability.Their simplicity is reflected in their simple composition and preparation methods used for QSFs.The diversity of supramolecular organic frameworks(SOFs) is reflected in the synthesis methods and structural characteristics of the as-obtained QSFs,as well as the variety of structural directing agents and basic building blocks used to prepare QSFs.The modulability is reflected by the controllable channel size in the QSFs,which can be adjusted using different sizes of Q[n]s.In this work,the first re ported cucurbituril Q[6]was selected as the basic building block and three Q[6]-based su p ramolecular frameworks were obtained from aqueous HCl solutions in the presence of [CdCl_(4)]^(2-)respectively.The OSIQs are the main driving forces for the formation of these frameworks.This study shows the diversity of the QSFs.展开更多
The wide application of intelligent terminals in microgrids has fueled the surge of data amount in recent years.In real-world scenarios,microgrids must store large amounts of data efficiently while also being able to ...The wide application of intelligent terminals in microgrids has fueled the surge of data amount in recent years.In real-world scenarios,microgrids must store large amounts of data efficiently while also being able to withstand malicious cyberattacks.To meet the high hardware resource requirements,address the vulnerability to network attacks and poor reliability in the tradi-tional centralized data storage schemes,this paper proposes a secure storage management method for microgrid data that considers node trust and directed acyclic graph(DAG)consensus mechanism.Firstly,the microgrid data storage model is designed based on the edge computing technology.The blockchain,deployed on the edge computing server and combined with cloud storage,ensures reliable data storage in the microgrid.Secondly,a blockchain consen-sus algorithm based on directed acyclic graph data structure is then proposed to effectively improve the data storage timeliness and avoid disadvantages in traditional blockchain topology such as long chain construction time and low consensus efficiency.Finally,considering the tolerance differences among the candidate chain-building nodes to network attacks,a hash value update mechanism of blockchain header with node trust identification to ensure data storage security is proposed.Experimental results from the microgrid data storage platform show that the proposed method can achieve a private key update time of less than 5 milliseconds.When the number of blockchain nodes is less than 25,the blockchain construction takes no more than 80 mins,and the data throughput is close to 300 kbps.Compared with the traditional chain-topology-based consensus methods that do not consider node trust,the proposed method has higher efficiency in data storage and better resistance to network attacks.展开更多
Semiconductor nanocrystals directly grown on the conducting metal can lower the contact resistance and can benefit the electron transfer between the semiconductor and the metal. In the present work, CdO nanocrystals a...Semiconductor nanocrystals directly grown on the conducting metal can lower the contact resistance and can benefit the electron transfer between the semiconductor and the metal. In the present work, CdO nanocrystals are directly synthesized on the conducting Cd foil through a simple solvothermal method. Cd foil is used as the Cd2＋ source and the substrate. The average size of CdO nanocrystals is -23.1 nm by analyzing the XRD data. Moreover the growth mechanism is discussed. A hierarchic structure characterized by the nano rods and nano particles in the top and bottom layers, respectively, can be observed. From the UV-vis absorption analyzed by Taucs relation, the two different optical band gaps are obtained. The photoluminescence spectrum is obtained and studied.展开更多
It is difficult to analyze semantic relations automatically, especially the semantic relations of Chinese special sentence patterns. In this paper, we apply a novel model feature structure to represent Chinese semanti...It is difficult to analyze semantic relations automatically, especially the semantic relations of Chinese special sentence patterns. In this paper, we apply a novel model feature structure to represent Chinese semantic relations, which is formalized as ＂recursive directed graph＂. We focus on Chinese special sentence patterns, including the complex noun phrase, verb-complement structure, pivotal sentences, serial verb sentence and subject-predicate predicate sentence. Feature structure facilitates a richer Chinese semantic information extraction when compared with dependency structure. The results show that using recursive directed graph is more suitable for extracting Chinese complex semantic relations.展开更多
High-temperature infrared-regulating ceramics are essentialfoerxtreme-environmentapplicationsrequiring broadband infrared reflection(1-6μm),such as spacecraft thermal protection,military stealth systems,and related f...High-temperature infrared-regulating ceramics are essentialfoerxtreme-environmentapplicationsrequiring broadband infrared reflection(1-6μm),such as spacecraft thermal protection,military stealth systems,and related fields.Precise control of pore structures is crucial for enhancing ceramic infrared reflectance,as pores directly influence the scattering intensity and scattering path of radiation.However,achieving broadband reflectance above 0.9 remains challenging because of unclear pore-radiation interaction mechanisms and insufficient structural control.This study employs optical simulations to systematically analyze how pore parameters enhance infrared reflectance.The results demonstrate that pore sizes matching the infrared wavelength,highaspect ratios,and aligned orientations synergistically enhance reflection.Guided by simulations,directional pore-structured yttria-stabilized zirconia(YSZ)ceramics were fabricated via a rolling extrusion method using graphite flakes as sacrificial templates.The optimized ceramics exhibited tailored pore parameters(size:0.2-6μm,aspect ratio:3.2-3.9,orientation angle:<30°),achieving exceptional infrared reflectance(>0.9).This study clarifies pore-radiation interactions and presents a scalable strategy to produce advanced thermal shielding materials.展开更多
Carbon nanoparticle coatings on laser-patterned stainless-steel surfaces present a solid lubrication system where the pattern's recessions act as lubricant-retaining reservoirs.This study investigates the influenc...Carbon nanoparticle coatings on laser-patterned stainless-steel surfaces present a solid lubrication system where the pattern's recessions act as lubricant-retaining reservoirs.This study investigates the influence of the structural depth of line patterns coated with multi-walled carbon nanotubes(CNTs)and carbon onions(COs)on their respective potential to reduce friction and wear.Direct laser interference patterning(DLIP)with a pulse duration of 12 ps is used to create line patterns with three different structural depths at a periodicity of 3.5μm on AISI 304 steel platelets.Subsequently,electrophoretic deposition(EPD)is applied to form homogeneous carbon nanoparticle coatings on the patterned platelets.Tribological ball-on-disc experiments are conducted on the as-described surfaces with an alumina counter body at a load of 100 mN.The results show that the shallower the coated structure,the lower its coefficient of friction(COF),regardless of the particle type.Thereby,with a minimum of just below 0.20,CNTs reach lower COF values than COs over most of the testing period.The resulting wear tracks are characterized by scanning electron microscopy,transmission electron microscopy,and energy-dispersive X-ray spectroscopy.During friction testing,the CNTs remain in contact,and the immediate proximity,whereas the CO coating is largely removed.Regardless of structural depth,no oxidation occurs on CNT-coated surfaces,whereas minor oxidation is detected on CO-coated wear tracks.展开更多
A typical zeolite synthesis reaction mixture involves a framework atom source,a solvent,a mineraliser,and a structure directing agent.However,these components often have a dual function,and their impact on the nucleat...A typical zeolite synthesis reaction mixture involves a framework atom source,a solvent,a mineraliser,and a structure directing agent.However,these components often have a dual function,and their impact on the nucleation/crystallization process is difficult to establish straightforwardly.The present study deals with the structure directing effect of zinc on the preparation of zincosilicate RUB-17(RSN-type material).First,an attempt was made to introduce several other heteroatoms(Al,B,Ge,Mg,Li,and Zr)into the RSN framework under the same reaction conditions as those for Zn-RSN.Second,different Zn sources have been employed in order to study their impact on RUB-17 intermediates and the final product properties.The obtained series of samples were analysed by XRD,XRF,GISAXS,SEM,TEM,and TG as well as by Raman,NMR,infrared and solid state UV/VIS spectroscopy.The physicochemical analysis of the obtained solids was complemented by DFT modelling.The results show that a RSN-type material can be solely prepared in the Zn-containing systems,where zinc plays a structure directing role besides its function as a framework cation.Namely,the lov-unit,a basic building unit of the RSN framework,is formed at the very beginning of the crystallization no matter the zinc source employed.Yet,the differences in the crystallization of different systems and relatively long time needed for full transformation of the precursor indicate that there is some other limiting step that accounts for the formation of zeolites.展开更多
Non-surfactant diquaternary ammonium compounds have already been used for obtaining various zeolites in nanocrystalline form. However, facile synthesis of nanocrystals of mordenite (MOR) and beta (BEA) in this way rem...Non-surfactant diquaternary ammonium compounds have already been used for obtaining various zeolites in nanocrystalline form. However, facile synthesis of nanocrystals of mordenite (MOR) and beta (BEA) in this way remains challenging. Here, we present the direct synthesis of nanosized mordernite (MOR) and beta (BEA) zeolites with hexane- and p-xylene-bridged bis-methylpyrrolidinium, -methylpiperidinium and -DABCO diquats, which can be synthesized in a single step from common chemicals. Optimized recipes are presented for nanosized MOR (20–50 nm) and BEA (15–30 nm) zeolites. By investigating the solid products obtained during hydrothermal synthesis, the formation of nanocrystals can be linked to the strong interaction between diquat templates and aluminosilicate species during the induction stage, which limits the amorphous precursor particles to a size below 50 nm. Based on the textural and acidic properties, catalytic performance data are discussed evidencing the clear benefits of these nanosized zeolites over bulk reference samples in Friedel–Crafts reactions and n-alkane hydroconversion.展开更多
Rational design of organic structure-directing agents(OSDAs)is always regarded as a promising strategy to produce ZSM-48 with diverse configurations.However,to date,only OSDAs with alkyl and alkenyl groups have been e...Rational design of organic structure-directing agents(OSDAs)is always regarded as a promising strategy to produce ZSM-48 with diverse configurations.However,to date,only OSDAs with alkyl and alkenyl groups have been employed to produce ^(*)MRE zeolites with different structures.Aromatic heterocyclic groups were rarely considered for the synthesis of ZSM-48 with a unique nanostructure.In this work,a triazine-based bolaform quaternary ammonium bifunctional template was designed for the first time to fabricate nanorod stacked hierarchical ZSM-48(NSH-ZSM-48).Nanorod-stacked ZSM-48 with different SiO_(2)/Al_(2)O_(3) ratios ranging from 100 to 500 was obtained via a conventional procedure,using the synthesized s-triazine based OSDA,and a reasonable formation mechanism was proposed based on geometrical matching.We also demonstrated that the ZSM-48 nanorods piled up to form an ordered bird’s nest-like hollow sphere configuration.The synthesized NSH-ZSM-48 possesses abundant mesopores and a high surface area,attributed to the SDA’s mesopore-forming and nanonrod’s stacking abilities.In contrast to conventional materials,1 wt%Pd/NSH-ZSM-48 experiences a dramatic increase in the conversion(3.59%)and selectivity(95.7%)of a cyclohexanol/cyclohexanone mixture in the selective oxidation of cyclohexane,which are higher than those for silicalite-1 and SBA-15 with the same loading(2.11%/66.1%and 1.76%/68.5%,respectively).展开更多
Recently,organic-inorganic hybrid lead halides have been explored as photoluminescent(PL)materials with flexible structural tunabilities and high photoluminescence quantum efficiencies,which can be modified by the str...Recently,organic-inorganic hybrid lead halides have been explored as photoluminescent(PL)materials with flexible structural tunabilities and high photoluminescence quantum efficiencies,which can be modified by the structure regulating functions of organic cations.Here,by adopting different saturated organic cations as structure directing agents(SDAs),a series of organic-inorganic hybrid lead halides have been solvothermally synthesized and characterized with different structural types.Compound[(CH_(3))_(2)NH_(2)]_(2)[H_(2)DABCO]_(2)Pb_(3)I_(12)(1,DABCO=1,4-diazabicyclo[2.2.2]-octane)features a linear zerodimensional(0D)[Pb_(3)I_(12)]_(6)-trimer,and[(Me)_(6)-en]_(2)Pb_(3)I_(10)(2)and[H_(2)N-Prpipz]_(2)Pb_(3)Br_(10)(3)contain two different types of one-dimensional(1D)[Pb_(3)X_(10)]_(4)-chains based on the C_(3)-symterric[Pb_(3)X11]trimer and[PbX_(6)]unit,respectively.In the structures of H[(Me)_(2)-DABCO]Pb_(3)I_(9)(4)and H[(Me)4-pipz]Pb_(3)I_(9)(5,pipz=piperazine),the C_(3)-symmetric[Pb_(3)I_(11)]trimers are interlinked to form the same two-dimensional(2D)corrugated[Pb_(3)I_(9)]^(3-)layers.Under the excitation of UV irradiation,these hybrid lead halides exhibit tunable luminescence properties from yellow,orange to red emissions with the largest Stokes shift of 335 nm.The PL nature is also investigated based on temperature-dependent PL emission,time-resolved PL and theoretical calculations,etc.These hybrid lead halides provide new types of structural models to probe into the PL properties and understand the underlying structure-property relationship.展开更多
基金financially supported by the National Natural Science Foundation of China(No.51365024)Zhejiang Provincial Natural Science Foundation of China(No.LGG19E010003)。
文摘The directional structure of Ni60/high-aluminum bronze composite coating was formed using induction remelting and forced cooling.The microstructural evolution and the characteristics of interface growth were studied.The results showed that the remelted coating formed metallurgical bonding with the substrate.The micros tructures changed from plane crystal to dendrite,cellular dendrite,fine cellular dendrite,and then to dendrite again with the increase in the cooling rate.The crystal grew along the heat flow direction and had(111) and(200)preferred orientations when the cooling rate was 1.886 ml-min^(-1).mm^(-2).The plane crystal,dendrite and cellular dendrite were mainly composed of compounds and solid solutions with Ni,Fe and Cu,and they were surrounded by strengthening phases composed of Cr,C and B.The grain boundary of directional structure coatings showed the characteristic of regular eutectic growth,but grain boundary of remelted coating presented characteristic of divorced eutectic growth.The wear resistance of directional structure coatings is better than that of remelted coating.
基金This work was supported by National Natural Science Foundation of China(No.52105212)Sichuan Science and Technology Program(No.2023NSFSC0863)China Postdoctoral Science Foundation(No.2021M702712).
文摘Over the past two decades,superhydrophobic surfaces that are easily created have aroused considerable attention for their superior performances in various applications at room temperature.Nowadays,there is a growing demand in special fields for the development of surfaces that can resist wetting by high-temperature molten droplets(>1200°C)using facile design and fabrication strategies.Herein,bioinspired directional structures(BDSs)were prepared on Y2O3-stabilized ZrO2(YSZ)surfaces using femtosecond laser ablation.Benefiting from the anisotropic energy barriers,the BDSs featured with no additional modifiers showed a remarkable increase from 9.2°to 60°in the contact angle of CaO–MgO–Al2O3–SiO2(CMAS)melt and a 70.1%reduction in the spreading area of CMAS at 1250°C,compared with polished super-CMAS-melt-philic YSZ surfaces.Moreover,the BDSs demonstrated exceptional wetting inhibition even at 1400°C,with an increase from 3.3°to 31.3°in contact angle and a 67.9%decrease in spreading area.This work provides valuable insight and a facile preparation strategy for effectively inhibiting the wetting of molten droplets on super-melt-philic surfaces at extremely high temperatures.
基金the financial support from the Gansu Provincial Natural Science Foundation (No. 20JR5RA471)the National Natural Science Foundation of China (No. 51365024)。
文摘The Ni60/15wt% Cu directional structure coating was prepared by the composite technology of flame spraying, induction remelting,and forced cooling, and the effect of Cu on the microstructure, phase, hardness, and wear performance of Ni60 coatings was investigated. Results showed that Cu addition makes the microstructure of Ni60 directional structure coating more compact, and Cu is mainly enriched within the crystal grain, resulting in the formation of Cu_(3.8)Ni as the bonding phase. Compared with Ni60 directional structure coating, Ni60/Cu directional structure coating has a lower hardness, lower friction coefficient, and lower wear rate, which indicate that Cu can effectively enhance the antifriction performance of Ni60 directional structure coating.
文摘The dissipation theory was introduced into the solidification area to describe the inherent laws of solidification from a new viewpoint. Discussion demonstrates that the solid / liquid interface in a directionally solidified alloy belongs to a kind of dissipation structure
基金the financial support from the Basque Government(IT1291-19)from the Spanish Ministry of Science and Innovation(PID2019-108028GB-C21,CTQ2017-92173-EXP and IJC2018-038162-I)+2 种基金Technical and human support provided by SGIker(UPV/EHU,MICINN,GV/EJ,and ESF)HPC support from C3UPO are also acknowledgedthe ISIS Neutron and Muon Source for the award of beam time on GEM(experiment RB1920440).
文摘UiO-66,reported in 2008,inspired the ongoing chemistry of group 4 metal–organic frameworks and it is still one of the most studied MOFs due to its exceptional stability.The tightness of their building blocks and bond strength make it tough to access new topologies,unless the building blocks are changed or defect engineering is employed,which in turn lead to different nominal stoichiometries.However,well selected structure directing agents and harsh synthesis conditions allowed the isolation of the first polymorph of UiO-66,named EHU-30.Herein,we provide evidence for the generalization of the synthetic approach with four new EHU-30 isoreticular compounds,based on amino-functionalized linkers and zirconium and hafnium as metal centres:EHU-30-NH_(2)(M)and EHU-30-NHR(M)(M:Zr,Hf;R:2-carboxypropyl).The crystal structure analysis reveals that their framework is more porous than that of their polymorphic counterpart.Furthermore,due to the current relevance of MOFs in greenhouse gas capture and in water harvesting methodologies,we have explored CO_(2)and water vapour adsorption on the new polymorphic phases,by means of experimental and computational resources,and compared to the parent EHU-30.The amino functionalization makes the EHU-30 series more prone to CO_(2)and water vapour adsorption.Besides,the water adsorption isotherms show an interesting crossing sensitive to temperature,sorption cycles and functionalization of the linker,which has been attributed to a localized structural transformation from EHU-30 to UiO-66.Finally,time-of-flight(TOF)powder neutron diffraction experiments were also conducted to locate the preferred adsorption sites for water in functionalized and parent EHU-30 structures.
基金supported by the National Key Research and Development Program of China (2017YFB0702803)the National Natural Science Foundation of China (91545111, 91634201, 21773296, 21573282 and 21733013).
文摘Advanced solid-state NMR techniques,including PT-J-HMQC ^(27)Al/^(31)P double-resonance NMR,2D ^(31)P and 1H DQ-SQ MAS NMR experiments,have been used to study the structure-directing effect in the crystallization of the molecular sieve AlPO_(4) -11 synthesized by a solvent-free method.
基金We thank the EPSRC funding(grants EP/H024107/1,EP/I033459/1,EP/J015156/1)EU FP7 Micreagents(318671)。
文摘A one-pot strategy exploiting the structure directing effects of SeIV and TeIV heteroatoms has yielded the highest nuclearity noble metal containing polyoxometalates to date;including the palladium-rich selenotungstate isomers K_(28)[H_(12)Pd_(10)Se_(10)W_(52)O_(206)]·65H_(2)O(1)and K_(26)[H_(14)Pd_(10)Se_(10)W_(52)O_(2)06]·68H_(2)O(2),and the nanoscale tellurotungstate cluster Na_(40)[Pd_(6)Te_(19)W_(42)O_(190)]·76H_(2)O(3).These reaction systems exhibit remarkable structural flexibility and point to a new route towards the synthesis of complex heterometallic species,in which multiple lacunary polyoxometalate‘building blocks’have been assembled to trap a transient oxopalladate species suspected to play a role in the assembly of several common polyoxopalladates.Mass spectrometry has been applied to explore and compare the solution stability of compounds 1-3,demonstrating the markedly different properties of the SeIV and TeIV templated systems.Electrochemical analysis of 1 has been provided and is dominated by Pd redox processes,with reduction of the cluster resulting in electrodeposition of Pd metal and observation of the subsequent formation of PdO species,concurrent with previously reported oxopalladate containing species.
基金supported by the National Natural Science Foundation of China(Grant No.21802136)~~
文摘Zeolite synthesis in contemporary chemical industries is predominantly conducted using organic structure‐directing agents(OSDAs),which are chronically hazardous to humans and the environment.It is a growing trend to develop an eco‐friendly and nuisanceless OSDA for zeolite synthesis.Herein,choline is employed as a non‐toxic and green OSDA to synthesize high silica Y zeolite with SiO2/Al2O3 ratios of 6.5–6.8.The prepared Y zeolite samples exhibited outstanding(hydro)thermal stability at ultrahigh temperature owing to the higher SiO2/Al2O3 ratio.The XRF,SEM,29Si‐NMR and 13Na+results suggested that choline plays a structure‐directing role in the synthesis of Y zeolite,while the feed molar fraction of Na+is a crucial determinant for the framework SiO2/Al2O3 ratio and the crystal morphology.
基金supported by the National Natural Science Foundation of China(No.51078311)
文摘To compensate for the imperfection of traditional bi-directional evolutionary structural optimization, material interpolation scheme and sensitivity filter functions are introduced. A suitable filter can overcome the checkerboard and mesh-dependency. And the historical information on accurate elemental sensitivity numbers are used to keep the objective function converging steadily. Apart from rational intervals of the relevant important parameters, the concept of distinguishing between active and non-active elements design is proposed, which can be widely used for improving the function and artistry of structures directly, especially for a one whose accurate size is not given. Furthermore, user-friendly software packages are developed to enhance its accessibility for practicing engineers and architects. And to reduce the time cost for large timeconsuming complex structure optimization, parallel computing is built-in in the MATLAB codes. The program is easy to use for engineers who may not be familiar with either FEA or structure optimization. And developers can make a deep research on the algorithm by changing the MATLAB codes. Several classical examples are given to show that the improved BESO method is superior for its handy and utility computer program software.
基金funded by the National Natural Science Foundation of China (Nos. 21476066 and 51271074)
文摘Nickel coated diamond composite powders were fabricated via a newly developed direct electrodeposition technique. The effects of activators on the coating of diamond were firstly investigated and diamond grinding wheels were then prepared from Ni-coated diamond composite powders with different activators. The microstructural characterizations of this composite powders were finally conducted by scanning electron microscopy, energy dispersive spectroscopy, and X-ray diffraction, and the mechanical and tribological properties of as-prepared diamond grinding wheels were also measured. There are changes in microstructures and properties of the composite powders with activators. The activator concentration also has an influence on the morphologies and phase structures of the Ni coating on diamond particles.The composite powders with more compact coating of nickel can be prepared by adding 1 g dm^（-3） or more AgNO_3 as an activator to electrodeposit nickel on diamond. The mechanical and tribological properties of diamond grinding wheels were significantly improved when the coating phase structure of Ni crystal grew with（111） plane orientation on the surface of diamond particles. The wheels made from nickel coated diamond composite powders possessed the advantages of easy preparation and outstanding tribological properties. Therefore, Ni coated diamond composite powders exhibit a great potential to be extensively applied in diamond cutting and grinding tools.
基金the financial support of the National Natural Science Foundation of China(Nos.21761007,51663005 and 21871064)Science and Technology Plan Project of Guizhou Province(Nos.20175788 and 20185781)。
文摘Curcurbit[n]uril(Q[n])-based supramolecular frameworks(QSFs) constructed from the outer surface interaction of Q[n]s(OSIQ) have the characteristic of simplicity,diversity and modulability.Their simplicity is reflected in their simple composition and preparation methods used for QSFs.The diversity of supramolecular organic frameworks(SOFs) is reflected in the synthesis methods and structural characteristics of the as-obtained QSFs,as well as the variety of structural directing agents and basic building blocks used to prepare QSFs.The modulability is reflected by the controllable channel size in the QSFs,which can be adjusted using different sizes of Q[n]s.In this work,the first re ported cucurbituril Q[6]was selected as the basic building block and three Q[6]-based su p ramolecular frameworks were obtained from aqueous HCl solutions in the presence of [CdCl_(4)]^(2-)respectively.The OSIQs are the main driving forces for the formation of these frameworks.This study shows the diversity of the QSFs.
文摘The wide application of intelligent terminals in microgrids has fueled the surge of data amount in recent years.In real-world scenarios,microgrids must store large amounts of data efficiently while also being able to withstand malicious cyberattacks.To meet the high hardware resource requirements,address the vulnerability to network attacks and poor reliability in the tradi-tional centralized data storage schemes,this paper proposes a secure storage management method for microgrid data that considers node trust and directed acyclic graph(DAG)consensus mechanism.Firstly,the microgrid data storage model is designed based on the edge computing technology.The blockchain,deployed on the edge computing server and combined with cloud storage,ensures reliable data storage in the microgrid.Secondly,a blockchain consen-sus algorithm based on directed acyclic graph data structure is then proposed to effectively improve the data storage timeliness and avoid disadvantages in traditional blockchain topology such as long chain construction time and low consensus efficiency.Finally,considering the tolerance differences among the candidate chain-building nodes to network attacks,a hash value update mechanism of blockchain header with node trust identification to ensure data storage security is proposed.Experimental results from the microgrid data storage platform show that the proposed method can achieve a private key update time of less than 5 milliseconds.When the number of blockchain nodes is less than 25,the blockchain construction takes no more than 80 mins,and the data throughput is close to 300 kbps.Compared with the traditional chain-topology-based consensus methods that do not consider node trust,the proposed method has higher efficiency in data storage and better resistance to network attacks.
基金Supported by the National Natural Science Foundation of China under Grant Nos U1262112 and 51176205
文摘Semiconductor nanocrystals directly grown on the conducting metal can lower the contact resistance and can benefit the electron transfer between the semiconductor and the metal. In the present work, CdO nanocrystals are directly synthesized on the conducting Cd foil through a simple solvothermal method. Cd foil is used as the Cd2＋ source and the substrate. The average size of CdO nanocrystals is -23.1 nm by analyzing the XRD data. Moreover the growth mechanism is discussed. A hierarchic structure characterized by the nano rods and nano particles in the top and bottom layers, respectively, can be observed. From the UV-vis absorption analyzed by Taucs relation, the two different optical band gaps are obtained. The photoluminescence spectrum is obtained and studied.
基金Supported by the National Natural Science Foundation of China(61202193,61202304)the Major Projects of Chinese National Social Science Foundation(11&ZD189)+2 种基金the Chinese Postdoctoral Science Foundation(2013M540593,2014T70722)the Accomplishments of Listed Subjects in Hubei Prime Subject Developmentthe Open Foundation of Shandong Key Lab of Language Resource Development and Application
文摘It is difficult to analyze semantic relations automatically, especially the semantic relations of Chinese special sentence patterns. In this paper, we apply a novel model feature structure to represent Chinese semantic relations, which is formalized as ＂recursive directed graph＂. We focus on Chinese special sentence patterns, including the complex noun phrase, verb-complement structure, pivotal sentences, serial verb sentence and subject-predicate predicate sentence. Feature structure facilitates a richer Chinese semantic information extraction when compared with dependency structure. The results show that using recursive directed graph is more suitable for extracting Chinese complex semantic relations.
基金supported by the National Natural Science Foundation of China(No.52371052).
文摘High-temperature infrared-regulating ceramics are essentialfoerxtreme-environmentapplicationsrequiring broadband infrared reflection(1-6μm),such as spacecraft thermal protection,military stealth systems,and related fields.Precise control of pore structures is crucial for enhancing ceramic infrared reflectance,as pores directly influence the scattering intensity and scattering path of radiation.However,achieving broadband reflectance above 0.9 remains challenging because of unclear pore-radiation interaction mechanisms and insufficient structural control.This study employs optical simulations to systematically analyze how pore parameters enhance infrared reflectance.The results demonstrate that pore sizes matching the infrared wavelength,highaspect ratios,and aligned orientations synergistically enhance reflection.Guided by simulations,directional pore-structured yttria-stabilized zirconia(YSZ)ceramics were fabricated via a rolling extrusion method using graphite flakes as sacrificial templates.The optimized ceramics exhibited tailored pore parameters(size:0.2-6μm,aspect ratio:3.2-3.9,orientation angle:<30°),achieving exceptional infrared reflectance(>0.9).This study clarifies pore-radiation interactions and presents a scalable strategy to produce advanced thermal shielding materials.
基金financial support by the Deutsche Forschungsgemeinschaft(DFG,German Research Foundation)within the project MU 959/47-1Furthermore,the authors gratefully acknowledge funding in the ZuMat projectsupported by the State of Saarland from the European Regional Development Fund(Europäischer Fonds für Regionale Entwicklung,EFRE).P.Grützmacher and C.Gachot would like to thank the Government of Lower Austria(WST3)for financially supporting the endowed professorship tribology at the TU Wien.V.Presser thanks Eduard Arzt(INM)for his continuing support.
文摘Carbon nanoparticle coatings on laser-patterned stainless-steel surfaces present a solid lubrication system where the pattern's recessions act as lubricant-retaining reservoirs.This study investigates the influence of the structural depth of line patterns coated with multi-walled carbon nanotubes(CNTs)and carbon onions(COs)on their respective potential to reduce friction and wear.Direct laser interference patterning(DLIP)with a pulse duration of 12 ps is used to create line patterns with three different structural depths at a periodicity of 3.5μm on AISI 304 steel platelets.Subsequently,electrophoretic deposition(EPD)is applied to form homogeneous carbon nanoparticle coatings on the patterned platelets.Tribological ball-on-disc experiments are conducted on the as-described surfaces with an alumina counter body at a load of 100 mN.The results show that the shallower the coated structure,the lower its coefficient of friction(COF),regardless of the particle type.Thereby,with a minimum of just below 0.20,CNTs reach lower COF values than COs over most of the testing period.The resulting wear tracks are characterized by scanning electron microscopy,transmission electron microscopy,and energy-dispersive X-ray spectroscopy.During friction testing,the CNTs remain in contact,and the immediate proximity,whereas the CO coating is largely removed.Regardless of structural depth,no oxidation occurs on CNT-coated surfaces,whereas minor oxidation is detected on CO-coated wear tracks.
基金Croatian Science Foundation,project number O-2594-2018supported by the University of Rijeka under the project number 13.2.1.3.04.
文摘A typical zeolite synthesis reaction mixture involves a framework atom source,a solvent,a mineraliser,and a structure directing agent.However,these components often have a dual function,and their impact on the nucleation/crystallization process is difficult to establish straightforwardly.The present study deals with the structure directing effect of zinc on the preparation of zincosilicate RUB-17(RSN-type material).First,an attempt was made to introduce several other heteroatoms(Al,B,Ge,Mg,Li,and Zr)into the RSN framework under the same reaction conditions as those for Zn-RSN.Second,different Zn sources have been employed in order to study their impact on RUB-17 intermediates and the final product properties.The obtained series of samples were analysed by XRD,XRF,GISAXS,SEM,TEM,and TG as well as by Raman,NMR,infrared and solid state UV/VIS spectroscopy.The physicochemical analysis of the obtained solids was complemented by DFT modelling.The results show that a RSN-type material can be solely prepared in the Zn-containing systems,where zinc plays a structure directing role besides its function as a framework cation.Namely,the lov-unit,a basic building unit of the RSN framework,is formed at the very beginning of the crystallization no matter the zinc source employed.Yet,the differences in the crystallization of different systems and relatively long time needed for full transformation of the precursor indicate that there is some other limiting step that accounts for the formation of zeolites.
文摘Non-surfactant diquaternary ammonium compounds have already been used for obtaining various zeolites in nanocrystalline form. However, facile synthesis of nanocrystals of mordenite (MOR) and beta (BEA) in this way remains challenging. Here, we present the direct synthesis of nanosized mordernite (MOR) and beta (BEA) zeolites with hexane- and p-xylene-bridged bis-methylpyrrolidinium, -methylpiperidinium and -DABCO diquats, which can be synthesized in a single step from common chemicals. Optimized recipes are presented for nanosized MOR (20–50 nm) and BEA (15–30 nm) zeolites. By investigating the solid products obtained during hydrothermal synthesis, the formation of nanocrystals can be linked to the strong interaction between diquat templates and aluminosilicate species during the induction stage, which limits the amorphous precursor particles to a size below 50 nm. Based on the textural and acidic properties, catalytic performance data are discussed evidencing the clear benefits of these nanosized zeolites over bulk reference samples in Friedel–Crafts reactions and n-alkane hydroconversion.
基金financially supported by the National Natural Science Foundation of China(21776311 and 22102215)Taishan Scholar Foundation(tspd20210308)+3 种基金the“111”Program of National College Disciplinary Innovation(B13031)Shandong Provincial Natural Science Foundation,China(ZR2019MB045 and ZR2019MB022)the National Key Technologies R&D Program of China,the Key Projects of Intergovernmental International Innovation Cooperation(2018YFE0118200)the Key Research and Development Project of Shandong province(2019JZZY010506).
文摘Rational design of organic structure-directing agents(OSDAs)is always regarded as a promising strategy to produce ZSM-48 with diverse configurations.However,to date,only OSDAs with alkyl and alkenyl groups have been employed to produce ^(*)MRE zeolites with different structures.Aromatic heterocyclic groups were rarely considered for the synthesis of ZSM-48 with a unique nanostructure.In this work,a triazine-based bolaform quaternary ammonium bifunctional template was designed for the first time to fabricate nanorod stacked hierarchical ZSM-48(NSH-ZSM-48).Nanorod-stacked ZSM-48 with different SiO_(2)/Al_(2)O_(3) ratios ranging from 100 to 500 was obtained via a conventional procedure,using the synthesized s-triazine based OSDA,and a reasonable formation mechanism was proposed based on geometrical matching.We also demonstrated that the ZSM-48 nanorods piled up to form an ordered bird’s nest-like hollow sphere configuration.The synthesized NSH-ZSM-48 possesses abundant mesopores and a high surface area,attributed to the SDA’s mesopore-forming and nanonrod’s stacking abilities.In contrast to conventional materials,1 wt%Pd/NSH-ZSM-48 experiences a dramatic increase in the conversion(3.59%)and selectivity(95.7%)of a cyclohexanol/cyclohexanone mixture in the selective oxidation of cyclohexane,which are higher than those for silicalite-1 and SBA-15 with the same loading(2.11%/66.1%and 1.76%/68.5%,respectively).
基金support from the National Nature Science Foundation of China(No.21571081,21671080 and 21601181)Fund of State Key Laboratory of Structural Chemistry(No.20170011)+2 种基金a Project of Shandong Province Higher Educational Science and Technology Program(J18kz005)Laboratory Open Foundation of Qufu Normal University(sk201722)the Cultivating Project for Talent Team and Ascendant Subject of University in Shandong Province.
文摘Recently,organic-inorganic hybrid lead halides have been explored as photoluminescent(PL)materials with flexible structural tunabilities and high photoluminescence quantum efficiencies,which can be modified by the structure regulating functions of organic cations.Here,by adopting different saturated organic cations as structure directing agents(SDAs),a series of organic-inorganic hybrid lead halides have been solvothermally synthesized and characterized with different structural types.Compound[(CH_(3))_(2)NH_(2)]_(2)[H_(2)DABCO]_(2)Pb_(3)I_(12)(1,DABCO=1,4-diazabicyclo[2.2.2]-octane)features a linear zerodimensional(0D)[Pb_(3)I_(12)]_(6)-trimer,and[(Me)_(6)-en]_(2)Pb_(3)I_(10)(2)and[H_(2)N-Prpipz]_(2)Pb_(3)Br_(10)(3)contain two different types of one-dimensional(1D)[Pb_(3)X_(10)]_(4)-chains based on the C_(3)-symterric[Pb_(3)X11]trimer and[PbX_(6)]unit,respectively.In the structures of H[(Me)_(2)-DABCO]Pb_(3)I_(9)(4)and H[(Me)4-pipz]Pb_(3)I_(9)(5,pipz=piperazine),the C_(3)-symmetric[Pb_(3)I_(11)]trimers are interlinked to form the same two-dimensional(2D)corrugated[Pb_(3)I_(9)]^(3-)layers.Under the excitation of UV irradiation,these hybrid lead halides exhibit tunable luminescence properties from yellow,orange to red emissions with the largest Stokes shift of 335 nm.The PL nature is also investigated based on temperature-dependent PL emission,time-resolved PL and theoretical calculations,etc.These hybrid lead halides provide new types of structural models to probe into the PL properties and understand the underlying structure-property relationship.
