We designed and constructed a new family of 608 dendritic dipyridyl donors, from which two novel triangular metallodendrimers were successfully prepared via coordination-driven self-assembly.Inspired by the existence ...We designed and constructed a new family of 608 dendritic dipyridyl donors, from which two novel triangular metallodendrimers were successfully prepared via coordination-driven self-assembly.Inspired by the existence of multiple intermolecular interactions（e.g., p–p stacking and CH–p interactions） imposed by the DMIP-functionalized poly（benzyl ether） dendrons, their hierarchical selfassembly behaviors were studied in various mixed solvents by using scanning electron microscopy（SEM）. Interestingly, it was found that the morphologies of the obtained metallodendrimers were highly depended on the dendron generation. For example, the first-generation metallodendrimer was able to hierarchically self-assemble into the spherical nanostructures in various mixed solvents. However, the nanofibers were observed for the second-generation metallodendrimer under the similar conditions.Furthermore, the driven force for the formation of such ordered nanostructures was investigated by using1 H NMR and fluorescence spectroscopy.展开更多
Long-range ordered nanostructures are prepared in the poly（styrene）-block-poly（e-caprolactone） diblock copolymer thin films using micromolding. We evaluated the change in crystallinity based on grazing-incidence X...Long-range ordered nanostructures are prepared in the poly（styrene）-block-poly（e-caprolactone） diblock copolymer thin films using micromolding. We evaluated the change in crystallinity based on grazing-incidence X-ray diffraction and proved that the crystallinity increased with the decrease of the mold size. This means that ordered nanostructures with atomic length scale order can be adjusted by tuning the mesoscale confinement. The inherent mechanism was the cooperation of geometric confinement, microphase structure and surface-induced ordering of PS-b-PCL in the melt, which paved the way for the subsequent crystal growth. These findings establish a route to promote the cost-effective nanofabrication by combining the mature microfabrication technique with the emerging directed self-assembly of block copolymers.展开更多
Herein,a ternary supramolecular assembly(BPP-BQ?CB[8]-SCD)is successfully constructed by a bromophenylpyridine-tethered-bromoisoquinoline(BPP-BQ),cucurbit[8]uril(CB[8])and sulfonatedβ-cyclodextrin(SCD)via successive ...Herein,a ternary supramolecular assembly(BPP-BQ?CB[8]-SCD)is successfully constructed by a bromophenylpyridine-tethered-bromoisoquinoline(BPP-BQ),cucurbit[8]uril(CB[8])and sulfonatedβ-cyclodextrin(SCD)via successive assembling way,exhibiting progressively enhanced green roomtemperature phosphorescence(RTP).The self-aggregates of BPP-BQ?CB[8]-SCD accommodate an energy acceptor rhodamine B(Rh B)to form a light-harvesting system(BPP-BQ?CB[8]-SCD@Rh B)with further enhanced yellow long-lifetime luminescence with large Stokes shift based on triplet-singlet F?rster resonance energy transfer(TS-FRET).Crucially,the introduction of a photoactive diarylethene achieves the long-lived photoluminescence of BPP-BQ?CB[8]-SCD@Rh B to be switched with the efficiency of up to98%through logically ordered lowering/enhancing RTP performance of the energy donor and intercepting/restoring TS-FRET pathway,when stimulated by host-vip competition and light illumination in sequence.Moreover,BPP-BQ?CB[8]-SCD@Rh B is evenly doped into polyvinyl alcohol or polyacrylamide to obtain high-performance luminescent films with long afterglow.The abovementioned logically ordered stimulus-switched long-lived emission enables the light-harvesting system in both solution and solid state to be applied in high-security-level information encryption and transformation,and anticounterfeiting.展开更多
meso-Tetrakis（4-aminophenyl）porphyrin（TAPP） can self-assemble into nanostructures with different morphologies by a phase-transfer method.The morphologies（nanospheres,nanorods and nanothorns）of porphyrin nanoaggr...meso-Tetrakis（4-aminophenyl）porphyrin（TAPP） can self-assemble into nanostructures with different morphologies by a phase-transfer method.The morphologies（nanospheres,nanorods and nanothorns）of porphyrin nanoaggregates could be easily tuned just by changing the concentration of porphyrin in a proper solvent at room temperature.HRTEM images revealed the formation of highly ordered supramolecular arrays of TAPP,i.e. superlattice of TAPP molecules in nanoaggregates,which agreed well with the size of one molecule of TAPP.UV–vis absorption spectra showed an obvious red shift of the Soret band of TAPP,indicating the formation of J-aggregates of TAPP in nanoaggregates.展开更多
Long-range magnetic order appears on a side decorated Heisenberg spin nanoribbon at nonzero temperature,although no spontaneous magnetization exists in a one-or two-dimensional isotropic Heisenberg model at any nonzer...Long-range magnetic order appears on a side decorated Heisenberg spin nanoribbon at nonzero temperature,although no spontaneous magnetization exists in a one-or two-dimensional isotropic Heisenberg model at any nonzero temperature according to the Mermin-Wagner theorem.By use of the spin Green's function method,we calculated the magnetizations of Heisenberg nanoribbons decorated by side spins with single-ion anisotropy and found that the system exhibits a nonzero transition temperature,whether the decorated edge spins of the system link together or separate from each other.When the width of the nanoribbon achieves infinite limit,the transition temperatures of the system tend to the same finite constant eventually whether one edge or both edges are decorated by side spins in the nanoribbon.The results reveal that the magnetism of a low-dimensional spin system is different from that of a threedimensional spin system.When the single-ion anisotropy of edge spins in a Heisenberg spin nanoribbon can be modulated by an electric field experimentally,various useful long-range magnetic orders of the system can be obtained.This work can provide a detailed theoretical basis for designing and fabricating next-generation low-dimensional magnetic random-access memory.展开更多
The assembly of a protein complex is very important for its biological function,which can be investigated by determining the order of assembly/disassembly of its protein subunits.Although static structures of many pro...The assembly of a protein complex is very important for its biological function,which can be investigated by determining the order of assembly/disassembly of its protein subunits.Although static structures of many protein com-plexes are available in the protein data bank,their assembly/disassembly orders of subunits are largely unknown.In addition to experimental techniques for studying subcomplexes in the assembly/disassembly of a protein complex,computational methods can be used to predict the assembly/disassembly order.Since sampling is a nontrivial issue in simulating the assembly/disassembly process,coarse-grained simulations are more efficient than atomic simulations are.In this work,we developed computational protocols for predicting the assembly/disassembly orders of protein complexes via coarse-grained simulations.The protocols were illustrated via two protein complexes,and the predicted assembly/disassembly orders were consistent with the available experimental data.展开更多
It is important to plan the assembling order automatically in order to reach assembling mechanization, especially intellectualization. The foundation of assembling order is how to understanding assembly drawing automa...It is important to plan the assembling order automatically in order to reach assembling mechanization, especially intellectualization. The foundation of assembling order is how to understanding assembly drawing automatically, namely the capacity of machine “drawing reading”. This paper introduces the general structure of ESUAD(Expert System of Understanding Assembly Drawing) system, its knowledge representation, the automatical understanding of assembly drawing, the plan of assembling order. Finally the paper will give the experiment result.展开更多
Macroscopic supramolecular assembly(MSA)has been a recent progress in supramolecular chemistry.MSA mainly focuses on studies of the building blocks with a size beyond ten micrometers and the non-covalent interactions ...Macroscopic supramolecular assembly(MSA)has been a recent progress in supramolecular chemistry.MSA mainly focuses on studies of the building blocks with a size beyond ten micrometers and the non-covalent interactions between these interactive building blocks to form ordered structures.MSA is essential to realize the concept of"self-assembly at all scales"by bridging most supramolecular researches at molecular level and at macroscopic scale.This review summaries the development of MSA,the basic design principle and related strategies to achieve MSA and potential applications.Correspondingly,we try to elucidate the correlations and differences between"macroscopic assembly"and MSA based on intermolecular interactions;the design principle and the underlying assembly mechanism of MSA are proposed to understand the reported MSA behaviors;to demonstrate further applications of MSA,we introduce some methods to improve the ordered degree of the assembled structures from the point of precise assembly and thus envision some possible fields for the use of MSA.展开更多
Ordered mesoporous silica were synthesized under different conditions:hydrothermal synthesis in basic medium,room temperature synthesis in acid medium and sol gel synthesis in neutral medium,and pore structure,specif...Ordered mesoporous silica were synthesized under different conditions:hydrothermal synthesis in basic medium,room temperature synthesis in acid medium and sol gel synthesis in neutral medium,and pore structure,specific surface area and pore size distribution of samples were studied and compared in detail by means of SAXRD,HRTEM,BET,FT IR.The results show that the mesopores in the samples obtained via above three methods all possess uniform hexagonal arrays in short range.Mesoporous silica obtained in acid medium possesses narrow pore size distribution centered around 1.24nm with specific surface area of 1220 m 2·g -1 ;Mesoporous silica obtained in basic medium by hydrothermal synthesis at 160℃ possesses narrow pore size distribution centered around 1.90nm with specific surface area of 542.8 m 2·g -1 ;and mesoporous silica obtained in neutral medium by sol gel synthesis possesses broader pore size distribution centered around 4.01nm,specific surface area of 485.0 m 2·g -1 .Therefore,ordered mesoporous silicas with different pore sizes can be prepared using various synthetic methods and conditions.After heat treatment,Si O Si bending vibration strengthens and the adsorption peak of asymmetrical Si O Si stretching vibration broadens,and the crosslinking and condensation reaction of silica skeleton strengthen, meanwhile the amount of active centers of hydroxyl group on the surface of mesopores may be influenced,thus chemical assembly activity of mesopores may also be influenced.展开更多
Numerous clothing enterprises in the market have a relatively low efficiency of assembly line planning due to insufficient optimization of bottleneck stations.As a result,the production efficiency of the enterprise is...Numerous clothing enterprises in the market have a relatively low efficiency of assembly line planning due to insufficient optimization of bottleneck stations.As a result,the production efficiency of the enterprise is not high,and the production organization is not up to expectations.Aiming at the problem of flexible process route planning in garment workshops,a multi-object genetic algorithm is proposed to solve the assembly line bal-ance optimization problem and minimize the machine adjustment path.The encoding method adopts the object-oriented path representation method,and the initial population is generated by random topology sorting based on an in-degree selection mechanism.The multi-object genetic algorithm improves the mutation and crossover operations according to the characteristics of the clothing process to avoid the generation of invalid offspring.In the iterative process,the bottleneck station is optimized by reasonable process splitting,and process allocation conforms to the strict limit of the station on the number of machines in order to improve the compilation efficiency.The effectiveness and feasibility of the multi-object genetic algorithm are proven by the analysis of clothing cases.Compared with the artificial allocation process,the compilation efficiency of MOGA is increased by more than 15%and completes the optimization of the minimum machine adjustment path.The results are in line with the expected optimization effect.展开更多
An interesting order-order transition between two different complex nanostructures was observed in a new liquid crystalline linear coil-coil-rod ABC triblock copolymer（tri BCP）. First, the ABC tri BCP, poly（dimethy...An interesting order-order transition between two different complex nanostructures was observed in a new liquid crystalline linear coil-coil-rod ABC triblock copolymer（tri BCP）. First, the ABC tri BCP, poly（dimethylsiloxane）-bpolystyrene-b-poly{2,5-bis[（4-methoxyphenyl）oxycarbonyl]styrene}（PDMS-b-PS-b-PMPCS）, was synthesized through sequential atom transfer radical polymerization. The degrees of polymerization of PDMS, PS, and PMPCS blocks are 58, 159, and 106, and the corresponding volume fractions of PDMS, PS, and PMPCS are 0.09, 0.29, and 0.62, respectively. The phase behaviors of the PDMS-b-PS diblock copolymer precursor and the final triblock copolymer were studied by smallangle X-ray scattering, one-dimensional wide-angle X-ray scattering, and transmission electron microscopy experiments. The PDMS-b-PS precursor self-assembles into hexagonally packed cylinders with a relatively small periodic size after thermal annealing. When the triblock copolymer is annealed at a relatively low temperature（120 ○C） at which the PMPCS block is in the amorphous state, the tri BCP forms core-shell hexagonally packed cylinders（CSH） with a relativly large periodic size. After the tri BCP is annealed above 140 ○C at which the PMPCS block transforms to the liquid crystalline（LC） phase, the nanophase-separated structure transforms to a three-phase four-layer lamellar structure（LAM-3P4L）. Thus, accompanied with the transition of the PMPCS blocks from the amorphous state to the LC phase, the order-order transition from CSH to LAM-3P4 L occurs in the PDMS-b-PS-b-PMPCS ABC tri BCP.展开更多
Spherical nanostructures with striped patterns on the surfaces resembling the essential structures of natural virus particles were constructed through a two-step self-assembly approach of polystyrene-boligo（acrylic a...Spherical nanostructures with striped patterns on the surfaces resembling the essential structures of natural virus particles were constructed through a two-step self-assembly approach of polystyrene-boligo（acrylic acid）（PS-b-oligo-AA） and poly（γ-benzyI L-glutamate）-b-poly（ethylene glycol）（PBLG-bPEG） copolymer mixtures in solution.On the basis of difference in hydrophilicity and self-assembly properties of the two copolymers,the two-step self-assembly process is realized.It was found that PS-boligo-AA copolymers formed spherical aggregates by adding a certain amount of water into polymer solutions in the first step.In the second step,two polymer solutions were mixed and water was further added,inducing the self-assembly of PBLG-b-PEG on the surfaces of PS-b-oligo-AA spheres to form striped patterns.In-depth study was conducted for the indispensable defects of striped patterns which are dislocations and ＋1/2 disclinations.The influencing factors such as the mixing ratio of two copolymers and the added water content in the first step on the morphology and defects of the striped patterns were investigated.This work not only presents an idea to interpret mechanism of the cooperative self-assembly behavior,but also provides an effective approach to construct virus-like particles and other complex structures with controllable morphology.展开更多
The long-period-stacking-ordered(LPSO)structure affects the mechanical,corrosion and hydrolysis properties of Mg alloys.The current work employs high angle annular dark field-scanning transmission electron microscopy(...The long-period-stacking-ordered(LPSO)structure affects the mechanical,corrosion and hydrolysis properties of Mg alloys.The current work employs high angle annular dark field-scanning transmission electron microscopy(HAADF-STEM)and atom probe tomography(APT)to investigate the structural and local chemical information of LPSO phases formed in Mg-Ni-Y/Sm ternary alloys after extended isothermal annealing.Depending on the alloying elements and their concentrations,Mg-Ni-Y/Sm develops a two-phase LPSO+α-Mg structure in which the LPSO phase contains defects,hybrid LPSO structure,and Mg insertions.HAADF-STEM and APT indicate non-stoichiometric LPSO with incomplete Ni_(6)(Y/Sm)_(8) clusters.In addition,the APT quantitatively determines the local composition of LPSO and confirms the presence of Ni within the Mg bonding layers.These results provide insight into a better understanding of the structure and hydrolysis properties of LPSO-Mg alloys.展开更多
The embedded atom method (EAM) was used to study the order-disorder transformation in gamma -TiAl alloy with L1(0). structure at stoichiometrical composition, and the effect of lattice constants was also investigated....The embedded atom method (EAM) was used to study the order-disorder transformation in gamma -TiAl alloy with L1(0). structure at stoichiometrical composition, and the effect of lattice constants was also investigated. It was found that the gamma -TiAl alloy at stoichiometrical composition exhibits a second-order transition, and the relations between lattice constants a, c and the long-range order sigma are not linear. The lattice constant a decreases whereas c increases with the increase of the long-range order parameter. In this case the ordering induces the transformation from cubic to tetragonal. The change of the lattice constant during the ordering processes can be interpreted in terms of bond length.展开更多
All intermetallic phases have a tendency to atomic long-range ordering, according to the ordering energy, they may be permanently ordered (up to the melting-point) or reversibly ordered (up to a critical temperature)....All intermetallic phases have a tendency to atomic long-range ordering, according to the ordering energy, they may be permanently ordered (up to the melting-point) or reversibly ordered (up to a critical temperature). The paper considers ways of disordering intermetallic phases, in relation to the ordering energy and diffusivities, and some properties of partially ordered intermetallic phases (including mechanical properties) The kinetics of re-ordering of disordered starting material will be examined,including sluggishly ordering phases (which can be aided by concurrent irradiation). The circumstances under which a partially disordered intermetallic phase may transform into an amorphous form will be outlined.展开更多
Three-dimensionally ordered self-assembly of monodispersed colloidal SiO2 particles involving a structure with periodic alternation of refractive indices represents an advanced field of particuology, colloidal chemist...Three-dimensionally ordered self-assembly of monodispersed colloidal SiO2 particles involving a structure with periodic alternation of refractive indices represents an advanced field of particuology, colloidal chemistry, materials science, optical physics and information science. Study on such self-assembly not only lays the foundation for the development of advanced functional materials, but also is significant in understanding the principles of nano- and micro-scale processes. Recent progress in three-dimensionally ordered self-assembly of colloidal SiO2 particles is reviewed, inclusive of the authors investigations.展开更多
Based on EAM (embedded atom method) interatomic potential, the effect of aluminum content on the type of order-disorder transformation (ODT) and the structure properties (lattice constants, volume, c/a ratio and confi...Based on EAM (embedded atom method) interatomic potential, the effect of aluminum content on the type of order-disorder transformation (ODT) and the structure properties (lattice constants, volume, c/a ratio and configu- ration energy) during ordering processes was investigated for γ-TiAI based alloys. Results show that for the alloys with lower than 50%Al (all composition is in atom number fraction), the ODT is the first order transition, and the second order transition for the alloys with equal or higher than 50% Al. The increase of aluminum content results in the critical temperature increasing. The aluminum content has a very little effect on the lattice constants, the volume and the c/a ratio, but has a significant effect on the configuration energy. A metastable disordered state was found for the alloys with less than 50%Al.展开更多
基金financial support of the National Natural Science Foundation of China (No. 21302058)the financial support of the Key Basic Research Project of Shanghai Science and Technology Commission (No. 13JC1402200)
文摘We designed and constructed a new family of 608 dendritic dipyridyl donors, from which two novel triangular metallodendrimers were successfully prepared via coordination-driven self-assembly.Inspired by the existence of multiple intermolecular interactions（e.g., p–p stacking and CH–p interactions） imposed by the DMIP-functionalized poly（benzyl ether） dendrons, their hierarchical selfassembly behaviors were studied in various mixed solvents by using scanning electron microscopy（SEM）. Interestingly, it was found that the morphologies of the obtained metallodendrimers were highly depended on the dendron generation. For example, the first-generation metallodendrimer was able to hierarchically self-assemble into the spherical nanostructures in various mixed solvents. However, the nanofibers were observed for the second-generation metallodendrimer under the similar conditions.Furthermore, the driven force for the formation of such ordered nanostructures was investigated by using1 H NMR and fluorescence spectroscopy.
基金financially supported by the National Natural Science Foundation of China(Nos.21274148 and 21074135)The experimental setup at the Nanofocus Endstation of MiNaXS was funded by the German Federal Ministry of Education and Research(projects BMBF 05KS7FK1 and 05K10FK3)
文摘Long-range ordered nanostructures are prepared in the poly（styrene）-block-poly（e-caprolactone） diblock copolymer thin films using micromolding. We evaluated the change in crystallinity based on grazing-incidence X-ray diffraction and proved that the crystallinity increased with the decrease of the mold size. This means that ordered nanostructures with atomic length scale order can be adjusted by tuning the mesoscale confinement. The inherent mechanism was the cooperation of geometric confinement, microphase structure and surface-induced ordering of PS-b-PCL in the melt, which paved the way for the subsequent crystal growth. These findings establish a route to promote the cost-effective nanofabrication by combining the mature microfabrication technique with the emerging directed self-assembly of block copolymers.
基金the National Natural Science Foundation of China(Nos.21801063,22305070 and U20041101)the Top-Notch Talents Program of Henan Agricultural University(Nos.30501049 and 30501032)for financial support。
文摘Herein,a ternary supramolecular assembly(BPP-BQ?CB[8]-SCD)is successfully constructed by a bromophenylpyridine-tethered-bromoisoquinoline(BPP-BQ),cucurbit[8]uril(CB[8])and sulfonatedβ-cyclodextrin(SCD)via successive assembling way,exhibiting progressively enhanced green roomtemperature phosphorescence(RTP).The self-aggregates of BPP-BQ?CB[8]-SCD accommodate an energy acceptor rhodamine B(Rh B)to form a light-harvesting system(BPP-BQ?CB[8]-SCD@Rh B)with further enhanced yellow long-lifetime luminescence with large Stokes shift based on triplet-singlet F?rster resonance energy transfer(TS-FRET).Crucially,the introduction of a photoactive diarylethene achieves the long-lived photoluminescence of BPP-BQ?CB[8]-SCD@Rh B to be switched with the efficiency of up to98%through logically ordered lowering/enhancing RTP performance of the energy donor and intercepting/restoring TS-FRET pathway,when stimulated by host-vip competition and light illumination in sequence.Moreover,BPP-BQ?CB[8]-SCD@Rh B is evenly doped into polyvinyl alcohol or polyacrylamide to obtain high-performance luminescent films with long afterglow.The abovementioned logically ordered stimulus-switched long-lived emission enables the light-harvesting system in both solution and solid state to be applied in high-security-level information encryption and transformation,and anticounterfeiting.
基金financially supported by the National Natural Science Foundation of China(Nos.51042013,21271119)Innovation Fund of Shanghai(No.10170502400)+1 种基金Science Foundation of Shandong Provincial Education Department(No.J08LC11)Research Progect of‘‘SUST Spring Bud’’(No.2008BWZ056)
文摘meso-Tetrakis（4-aminophenyl）porphyrin（TAPP） can self-assemble into nanostructures with different morphologies by a phase-transfer method.The morphologies（nanospheres,nanorods and nanothorns）of porphyrin nanoaggregates could be easily tuned just by changing the concentration of porphyrin in a proper solvent at room temperature.HRTEM images revealed the formation of highly ordered supramolecular arrays of TAPP,i.e. superlattice of TAPP molecules in nanoaggregates,which agreed well with the size of one molecule of TAPP.UV–vis absorption spectra showed an obvious red shift of the Soret band of TAPP,indicating the formation of J-aggregates of TAPP in nanoaggregates.
文摘Long-range magnetic order appears on a side decorated Heisenberg spin nanoribbon at nonzero temperature,although no spontaneous magnetization exists in a one-or two-dimensional isotropic Heisenberg model at any nonzero temperature according to the Mermin-Wagner theorem.By use of the spin Green's function method,we calculated the magnetizations of Heisenberg nanoribbons decorated by side spins with single-ion anisotropy and found that the system exhibits a nonzero transition temperature,whether the decorated edge spins of the system link together or separate from each other.When the width of the nanoribbon achieves infinite limit,the transition temperatures of the system tend to the same finite constant eventually whether one edge or both edges are decorated by side spins in the nanoribbon.The results reveal that the magnetism of a low-dimensional spin system is different from that of a threedimensional spin system.When the single-ion anisotropy of edge spins in a Heisenberg spin nanoribbon can be modulated by an electric field experimentally,various useful long-range magnetic orders of the system can be obtained.This work can provide a detailed theoretical basis for designing and fabricating next-generation low-dimensional magnetic random-access memory.
基金This work was supported by the National Key Research and Development Program of China(2021YFA1301504)the Chinese Academy of Sciences Strategic Priority Research Program(XDB37040202)the National Natural Science Foundation of China(91953101).
文摘The assembly of a protein complex is very important for its biological function,which can be investigated by determining the order of assembly/disassembly of its protein subunits.Although static structures of many protein com-plexes are available in the protein data bank,their assembly/disassembly orders of subunits are largely unknown.In addition to experimental techniques for studying subcomplexes in the assembly/disassembly of a protein complex,computational methods can be used to predict the assembly/disassembly order.Since sampling is a nontrivial issue in simulating the assembly/disassembly process,coarse-grained simulations are more efficient than atomic simulations are.In this work,we developed computational protocols for predicting the assembly/disassembly orders of protein complexes via coarse-grained simulations.The protocols were illustrated via two protein complexes,and the predicted assembly/disassembly orders were consistent with the available experimental data.
文摘It is important to plan the assembling order automatically in order to reach assembling mechanization, especially intellectualization. The foundation of assembling order is how to understanding assembly drawing automatically, namely the capacity of machine “drawing reading”. This paper introduces the general structure of ESUAD(Expert System of Understanding Assembly Drawing) system, its knowledge representation, the automatical understanding of assembly drawing, the plan of assembling order. Finally the paper will give the experiment result.
文摘Macroscopic supramolecular assembly(MSA)has been a recent progress in supramolecular chemistry.MSA mainly focuses on studies of the building blocks with a size beyond ten micrometers and the non-covalent interactions between these interactive building blocks to form ordered structures.MSA is essential to realize the concept of"self-assembly at all scales"by bridging most supramolecular researches at molecular level and at macroscopic scale.This review summaries the development of MSA,the basic design principle and related strategies to achieve MSA and potential applications.Correspondingly,we try to elucidate the correlations and differences between"macroscopic assembly"and MSA based on intermolecular interactions;the design principle and the underlying assembly mechanism of MSA are proposed to understand the reported MSA behaviors;to demonstrate further applications of MSA,we introduce some methods to improve the ordered degree of the assembled structures from the point of precise assembly and thus envision some possible fields for the use of MSA.
基金theNationalNaturalScienceFoundationofChina (No .50 2 72048)andtheNaturalScienceFoundationofHubeiProvince (No .2 0 0 1ABB0 76)
文摘Ordered mesoporous silica were synthesized under different conditions:hydrothermal synthesis in basic medium,room temperature synthesis in acid medium and sol gel synthesis in neutral medium,and pore structure,specific surface area and pore size distribution of samples were studied and compared in detail by means of SAXRD,HRTEM,BET,FT IR.The results show that the mesopores in the samples obtained via above three methods all possess uniform hexagonal arrays in short range.Mesoporous silica obtained in acid medium possesses narrow pore size distribution centered around 1.24nm with specific surface area of 1220 m 2·g -1 ;Mesoporous silica obtained in basic medium by hydrothermal synthesis at 160℃ possesses narrow pore size distribution centered around 1.90nm with specific surface area of 542.8 m 2·g -1 ;and mesoporous silica obtained in neutral medium by sol gel synthesis possesses broader pore size distribution centered around 4.01nm,specific surface area of 485.0 m 2·g -1 .Therefore,ordered mesoporous silicas with different pore sizes can be prepared using various synthetic methods and conditions.After heat treatment,Si O Si bending vibration strengthens and the adsorption peak of asymmetrical Si O Si stretching vibration broadens,and the crosslinking and condensation reaction of silica skeleton strengthen, meanwhile the amount of active centers of hydroxyl group on the surface of mesopores may be influenced,thus chemical assembly activity of mesopores may also be influenced.
基金supported by Key R&D project of Zhejiang Province (2018C01005),http://kjt.zj.gov.cn/.
文摘Numerous clothing enterprises in the market have a relatively low efficiency of assembly line planning due to insufficient optimization of bottleneck stations.As a result,the production efficiency of the enterprise is not high,and the production organization is not up to expectations.Aiming at the problem of flexible process route planning in garment workshops,a multi-object genetic algorithm is proposed to solve the assembly line bal-ance optimization problem and minimize the machine adjustment path.The encoding method adopts the object-oriented path representation method,and the initial population is generated by random topology sorting based on an in-degree selection mechanism.The multi-object genetic algorithm improves the mutation and crossover operations according to the characteristics of the clothing process to avoid the generation of invalid offspring.In the iterative process,the bottleneck station is optimized by reasonable process splitting,and process allocation conforms to the strict limit of the station on the number of machines in order to improve the compilation efficiency.The effectiveness and feasibility of the multi-object genetic algorithm are proven by the analysis of clothing cases.Compared with the artificial allocation process,the compilation efficiency of MOGA is increased by more than 15%and completes the optimization of the minimum machine adjustment path.The results are in line with the expected optimization effect.
基金supported by the National Natural Science Foundation of China(Nos.20874003 and 21174006)
文摘An interesting order-order transition between two different complex nanostructures was observed in a new liquid crystalline linear coil-coil-rod ABC triblock copolymer（tri BCP）. First, the ABC tri BCP, poly（dimethylsiloxane）-bpolystyrene-b-poly{2,5-bis[（4-methoxyphenyl）oxycarbonyl]styrene}（PDMS-b-PS-b-PMPCS）, was synthesized through sequential atom transfer radical polymerization. The degrees of polymerization of PDMS, PS, and PMPCS blocks are 58, 159, and 106, and the corresponding volume fractions of PDMS, PS, and PMPCS are 0.09, 0.29, and 0.62, respectively. The phase behaviors of the PDMS-b-PS diblock copolymer precursor and the final triblock copolymer were studied by smallangle X-ray scattering, one-dimensional wide-angle X-ray scattering, and transmission electron microscopy experiments. The PDMS-b-PS precursor self-assembles into hexagonally packed cylinders with a relatively small periodic size after thermal annealing. When the triblock copolymer is annealed at a relatively low temperature（120 ○C） at which the PMPCS block is in the amorphous state, the tri BCP forms core-shell hexagonally packed cylinders（CSH） with a relativly large periodic size. After the tri BCP is annealed above 140 ○C at which the PMPCS block transforms to the liquid crystalline（LC） phase, the nanophase-separated structure transforms to a three-phase four-layer lamellar structure（LAM-3P4L）. Thus, accompanied with the transition of the PMPCS blocks from the amorphous state to the LC phase, the order-order transition from CSH to LAM-3P4 L occurs in the PDMS-b-PS-b-PMPCS ABC tri BCP.
基金supported by the National Natural Science Foundation of China(Nos.21234002,51303055,21474029,and51573049)Support from projects of Shanghai municipality(Nos.15QA1401400 and 13JC1402000)
文摘Spherical nanostructures with striped patterns on the surfaces resembling the essential structures of natural virus particles were constructed through a two-step self-assembly approach of polystyrene-boligo（acrylic acid）（PS-b-oligo-AA） and poly（γ-benzyI L-glutamate）-b-poly（ethylene glycol）（PBLG-bPEG） copolymer mixtures in solution.On the basis of difference in hydrophilicity and self-assembly properties of the two copolymers,the two-step self-assembly process is realized.It was found that PS-boligo-AA copolymers formed spherical aggregates by adding a certain amount of water into polymer solutions in the first step.In the second step,two polymer solutions were mixed and water was further added,inducing the self-assembly of PBLG-b-PEG on the surfaces of PS-b-oligo-AA spheres to form striped patterns.In-depth study was conducted for the indispensable defects of striped patterns which are dislocations and ＋1/2 disclinations.The influencing factors such as the mixing ratio of two copolymers and the added water content in the first step on the morphology and defects of the striped patterns were investigated.This work not only presents an idea to interpret mechanism of the cooperative self-assembly behavior,but also provides an effective approach to construct virus-like particles and other complex structures with controllable morphology.
基金the financial support provided by ANR(Project ANR-22-PEHY-0007)DGA(French Direction Générale des Armées,2018600045)Région Nouvelle Aquitaine(agreement 2018–1R10126).
文摘The long-period-stacking-ordered(LPSO)structure affects the mechanical,corrosion and hydrolysis properties of Mg alloys.The current work employs high angle annular dark field-scanning transmission electron microscopy(HAADF-STEM)and atom probe tomography(APT)to investigate the structural and local chemical information of LPSO phases formed in Mg-Ni-Y/Sm ternary alloys after extended isothermal annealing.Depending on the alloying elements and their concentrations,Mg-Ni-Y/Sm develops a two-phase LPSO+α-Mg structure in which the LPSO phase contains defects,hybrid LPSO structure,and Mg insertions.HAADF-STEM and APT indicate non-stoichiometric LPSO with incomplete Ni_(6)(Y/Sm)_(8) clusters.In addition,the APT quantitatively determines the local composition of LPSO and confirms the presence of Ni within the Mg bonding layers.These results provide insight into a better understanding of the structure and hydrolysis properties of LPSO-Mg alloys.
基金This work was financially supported by the National Natural Science Foundation of China under Contract No.59895151-01
文摘The embedded atom method (EAM) was used to study the order-disorder transformation in gamma -TiAl alloy with L1(0). structure at stoichiometrical composition, and the effect of lattice constants was also investigated. It was found that the gamma -TiAl alloy at stoichiometrical composition exhibits a second-order transition, and the relations between lattice constants a, c and the long-range order sigma are not linear. The lattice constant a decreases whereas c increases with the increase of the long-range order parameter. In this case the ordering induces the transformation from cubic to tetragonal. The change of the lattice constant during the ordering processes can be interpreted in terms of bond length.
文摘All intermetallic phases have a tendency to atomic long-range ordering, according to the ordering energy, they may be permanently ordered (up to the melting-point) or reversibly ordered (up to a critical temperature). The paper considers ways of disordering intermetallic phases, in relation to the ordering energy and diffusivities, and some properties of partially ordered intermetallic phases (including mechanical properties) The kinetics of re-ordering of disordered starting material will be examined,including sluggishly ordering phases (which can be aided by concurrent irradiation). The circumstances under which a partially disordered intermetallic phase may transform into an amorphous form will be outlined.
基金supported by the Chinese National Key Basic Research Special Fund(Grant No.2001CB6104)the National Natural Science Foundation of China(Grant No.20076027)
文摘Three-dimensionally ordered self-assembly of monodispersed colloidal SiO2 particles involving a structure with periodic alternation of refractive indices represents an advanced field of particuology, colloidal chemistry, materials science, optical physics and information science. Study on such self-assembly not only lays the foundation for the development of advanced functional materials, but also is significant in understanding the principles of nano- and micro-scale processes. Recent progress in three-dimensionally ordered self-assembly of colloidal SiO2 particles is reviewed, inclusive of the authors investigations.
基金This work was financially supported by the National Natural Science Foundation of China (No. 59895151-01).
文摘Based on EAM (embedded atom method) interatomic potential, the effect of aluminum content on the type of order-disorder transformation (ODT) and the structure properties (lattice constants, volume, c/a ratio and configu- ration energy) during ordering processes was investigated for γ-TiAI based alloys. Results show that for the alloys with lower than 50%Al (all composition is in atom number fraction), the ODT is the first order transition, and the second order transition for the alloys with equal or higher than 50% Al. The increase of aluminum content results in the critical temperature increasing. The aluminum content has a very little effect on the lattice constants, the volume and the c/a ratio, but has a significant effect on the configuration energy. A metastable disordered state was found for the alloys with less than 50%Al.
