In this study, macroscopic graphene-wrapped melamine foams （MF-G） were fabricated by an MF-templated layer-by-layer （LBL） assembly using graphene oxide as building blocks, followed by solution-processed reduction....In this study, macroscopic graphene-wrapped melamine foams （MF-G） were fabricated by an MF-templated layer-by-layer （LBL） assembly using graphene oxide as building blocks, followed by solution-processed reduction. By concisely duplicating sponge-like, highly ordered three-dimensional architectures from MF, the resulting MF-G with an interconnected graphene-based scaffold and tunable nanostructure was explored as compressible, robust electrodes for efficient energy storage. A thin layer of pseudocapacitive polypyrrole （PPy） was then attached and uniformly coated on MF-G, resulting in a well-defined core- double-shell configuration of the MF-G-PPy ternary composite sponges. The as-assembled devices exhibited enhancement of supercapacitor performance, with a high specific capacitance of 427 F·g-1 under a compressive strain of 75% and an excellent cycling stability with only 18% degradation after 5,000 charge- discharge cycles. Besides, the MF-G-PPy electrode maintained stable capacitance up to 100 compression-release cycles, with a compressive strain of 75%. These encouraging results thus provide a new route towards the low-cost, easily scalable fabrication of lightweight and deformation-tolerant electrodes.展开更多
Highly ordered Bi4Si3O12 micro-crystals were prepared at normal atmosphere. Phase identification of the prepared crystals was accomplished by X-ray diffractometer (XRD). Domain structure and defects were characterized...Highly ordered Bi4Si3O12 micro-crystals were prepared at normal atmosphere. Phase identification of the prepared crystals was accomplished by X-ray diffractometer (XRD). Domain structure and defects were characterized by environmental scanning electron microscopy (ESEM). XRD shows that the obtained micro-crystals are of eulytite structure with chemical formulation of Bi4Si3O12. A highly ordered growth pattern is confirmed due to the faster growth of the {124} faces than that of the {204} faces by ESEM. The growing process of the domain structure is of pollen parent and filial generation pattern. The filial generations of Bi4Si3O12 crystals are generated from the pollen parent. Cracks generate from the defect areas and propagate along the {124} faces due to their lower binding energy under a proper temperature gradient, contributing to the total transcrystalline fracture. It is confirmed that the generation and development of the voids in the crystal grains can be developed when unmatched dimensions of the two opposite faces are formed. And the development of the voids is dependent on the dimensions and orientations of the two opposite faces.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
Small molecule peptides and their derivatives are an emerging class of supramolecular hydrogelators that have attracted rapidly growing interest in the fields of drug delivery and regenerative medicine due to their in...Small molecule peptides and their derivatives are an emerging class of supramolecular hydrogelators that have attracted rapidly growing interest in the fields of drug delivery and regenerative medicine due to their inherent biodegradability and biocompatibility, as well as versatility in molecular design and ease of synthesis. Built upon the directional, intermolecular interactions such as hydrogen bonding and π-π stacking, peptide-based molecular units can associate in aqueous solution into filamentous assemblies of various sizes and shapes. Under appropriate conditions, these filamentous assemblies can percolate into a 3D network with materials properties tailorable for specific biomedical applications. In this review, we survey the literature published over the past three years in the development of peptide-based hydrogelators for biomedical applications. We highlight several representative examples and center our discussion on the fundamentals of molecular design, assembly, and gelation conditions.展开更多
Nanobubbles have been proven existent at the liquid/solid interface, and become a focus of research on varied interfacial processes. In the present work, by observing in situ with atomic force microscope (AFM), we fou...Nanobubbles have been proven existent at the liquid/solid interface, and become a focus of research on varied interfacial processes. In the present work, by observing in situ with atomic force microscope (AFM), we found that nanobubbles could influence the adsorption process of bovine serum albumin (BSA) on hydrophobic surface of highly ordered pyrolytic graphite (HOPG). BSA could adsorb evenly, and coexist with nanobubbles at water/HOPG interface. After removing nanobubbles by injecting ethanol, some hollows were found in the BSA layers at the same positions of nanobubbles existing previously. These hollows were about 8 nm in depth and dozens of nanometers in diameter. The correlation coefficient between the areas of nanobubbles and that of the corresponding hollows reached 0.88―0.94, which strongly supported the assumption that the hollows were indeed caused by the nanobubbles. Moreover, the BSA molecules formed rings around the nanobubbles, suggesting the preference of BSA adsorption onto the contact line at water/HOPG interface.展开更多
The nano materials often exhibit very interesting electrical, optical, magnetic, and chemical properties, which can not be achieved by their bulk counterparts. The development of uniform nanometer sized particles has ...The nano materials often exhibit very interesting electrical, optical, magnetic, and chemical properties, which can not be achieved by their bulk counterparts. The development of uniform nanometer sized particles has been intensively pursued because of their technological and fundamental scientific importance. It is significant that nanostructured materials can be controllably assembled into the required geometry onto substrates, becoming the basis of the next generation of components and devices. The development of new methods and strategies for organizing the nanoparticle basic building blocks into the desired structures is required. Superlattices made from these building blocks give us the opportunity to study not only the properties of the individual building blocks, but also collective effects. The superparamagnetic iron oxide nanocrystals（NCs） have been used in the fields of bio-medicine, ferrofluids, refrigeration system, catalysis,展开更多
A.M.W. Glass and S.H.McCleary have given the 2 transitive representation of the countable free l group F η(1<η≤ω 0 ).In this paper we shall give the highly ordered transitive representation of count...A.M.W. Glass and S.H.McCleary have given the 2 transitive representation of the countable free l group F η(1<η≤ω 0 ).In this paper we shall give the highly ordered transitive representation of countable free groups on the rational line Q, which generalizes their results. As applications,we obtain the highly ordered transitive representation for the direct product of countable free groups,and the inverse limit of countable free groups must be an action on the set Q.展开更多
基金The authors gratefully acknowledge the National Natural Science Foundation of China （No. 21504012, 51125011 and 51433001） and the Fundamental Research Funds for the Central Universities of China （No. 16D110617）.
文摘In this study, macroscopic graphene-wrapped melamine foams （MF-G） were fabricated by an MF-templated layer-by-layer （LBL） assembly using graphene oxide as building blocks, followed by solution-processed reduction. By concisely duplicating sponge-like, highly ordered three-dimensional architectures from MF, the resulting MF-G with an interconnected graphene-based scaffold and tunable nanostructure was explored as compressible, robust electrodes for efficient energy storage. A thin layer of pseudocapacitive polypyrrole （PPy） was then attached and uniformly coated on MF-G, resulting in a well-defined core- double-shell configuration of the MF-G-PPy ternary composite sponges. The as-assembled devices exhibited enhancement of supercapacitor performance, with a high specific capacitance of 427 F·g-1 under a compressive strain of 75% and an excellent cycling stability with only 18% degradation after 5,000 charge- discharge cycles. Besides, the MF-G-PPy electrode maintained stable capacitance up to 100 compression-release cycles, with a compressive strain of 75%. These encouraging results thus provide a new route towards the low-cost, easily scalable fabrication of lightweight and deformation-tolerant electrodes.
基金Supported by the Innovation Research Team Funds of Shaanxi University of Science & Technology (Grant No. SUST-A04)
文摘Highly ordered Bi4Si3O12 micro-crystals were prepared at normal atmosphere. Phase identification of the prepared crystals was accomplished by X-ray diffractometer (XRD). Domain structure and defects were characterized by environmental scanning electron microscopy (ESEM). XRD shows that the obtained micro-crystals are of eulytite structure with chemical formulation of Bi4Si3O12. A highly ordered growth pattern is confirmed due to the faster growth of the {124} faces than that of the {204} faces by ESEM. The growing process of the domain structure is of pollen parent and filial generation pattern. The filial generations of Bi4Si3O12 crystals are generated from the pollen parent. Cracks generate from the defect areas and propagate along the {124} faces due to their lower binding energy under a proper temperature gradient, contributing to the total transcrystalline fracture. It is confirmed that the generation and development of the voids in the crystal grains can be developed when unmatched dimensions of the two opposite faces are formed. And the development of the voids is dependent on the dimensions and orientations of the two opposite faces.
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.
基金financially supported by the National Science Foundation(No.DMR 1255281)
文摘Small molecule peptides and their derivatives are an emerging class of supramolecular hydrogelators that have attracted rapidly growing interest in the fields of drug delivery and regenerative medicine due to their inherent biodegradability and biocompatibility, as well as versatility in molecular design and ease of synthesis. Built upon the directional, intermolecular interactions such as hydrogen bonding and π-π stacking, peptide-based molecular units can associate in aqueous solution into filamentous assemblies of various sizes and shapes. Under appropriate conditions, these filamentous assemblies can percolate into a 3D network with materials properties tailorable for specific biomedical applications. In this review, we survey the literature published over the past three years in the development of peptide-based hydrogelators for biomedical applications. We highlight several representative examples and center our discussion on the fundamentals of molecular design, assembly, and gelation conditions.
基金National Natural Science Foundation of China (Grant No. 20403010)
文摘Nanobubbles have been proven existent at the liquid/solid interface, and become a focus of research on varied interfacial processes. In the present work, by observing in situ with atomic force microscope (AFM), we found that nanobubbles could influence the adsorption process of bovine serum albumin (BSA) on hydrophobic surface of highly ordered pyrolytic graphite (HOPG). BSA could adsorb evenly, and coexist with nanobubbles at water/HOPG interface. After removing nanobubbles by injecting ethanol, some hollows were found in the BSA layers at the same positions of nanobubbles existing previously. These hollows were about 8 nm in depth and dozens of nanometers in diameter. The correlation coefficient between the areas of nanobubbles and that of the corresponding hollows reached 0.88―0.94, which strongly supported the assumption that the hollows were indeed caused by the nanobubbles. Moreover, the BSA molecules formed rings around the nanobubbles, suggesting the preference of BSA adsorption onto the contact line at water/HOPG interface.
基金Supported by the National Natural Science Foundation of China（Nos.60978062, 51203058）.
文摘The nano materials often exhibit very interesting electrical, optical, magnetic, and chemical properties, which can not be achieved by their bulk counterparts. The development of uniform nanometer sized particles has been intensively pursued because of their technological and fundamental scientific importance. It is significant that nanostructured materials can be controllably assembled into the required geometry onto substrates, becoming the basis of the next generation of components and devices. The development of new methods and strategies for organizing the nanoparticle basic building blocks into the desired structures is required. Superlattices made from these building blocks give us the opportunity to study not only the properties of the individual building blocks, but also collective effects. The superparamagnetic iron oxide nanocrystals（NCs） have been used in the fields of bio-medicine, ferrofluids, refrigeration system, catalysis,
文摘A.M.W. Glass and S.H.McCleary have given the 2 transitive representation of the countable free l group F η(1<η≤ω 0 ).In this paper we shall give the highly ordered transitive representation of countable free groups on the rational line Q, which generalizes their results. As applications,we obtain the highly ordered transitive representation for the direct product of countable free groups,and the inverse limit of countable free groups must be an action on the set Q.
