Selective hydrogenation of the carbonyl bond inα,β-unsaturated carbonyl compounds is rather challenging owing to the more feasible hydrogenation of ethylenic bond from both thermodynamic and kinetic aspects.Here,we ...Selective hydrogenation of the carbonyl bond inα,β-unsaturated carbonyl compounds is rather challenging owing to the more feasible hydrogenation of ethylenic bond from both thermodynamic and kinetic aspects.Here,we demonstrate a facile emulsionbased molecule-nanoparticle self-assembly strategy for the atomic engineering of Ir species on three-dimensional CeO_(2)spheres(Ir1@CeO_(2)).When applied to the hydrogenation ofα,β-unsaturated aldehydes,Ir1@CeO_(2)catalyst remarkably exhibited~100%selectivity towards unsaturated alcohols,whereas the formation of Ir nanoparticles on CeO_(2)drastically decreased the selectivity for unsaturated alcohols.Spectroscopic studies revealed that strong metal-support interactions triggered the charge transfer from Ir to CeO_(2),leading to the partial reduction of Ce^(4+)to Ce^(3+)along with the formation new Ir^(δ+)-O_(2)--Ce^(3+)(OV)interfaces.The electrophilic atomic Ir species at the Ir^(δ+)-O_(2)--Ce^(3+)(OV)interfaces would therefore preferentially adsorb and facilitate hydrogenation of polar C=O bond to achieve exceptional selectivity.展开更多
Uniform CdS colloidal spheres have been successfully synthesized via a simple hydrothermal method. X-ray diffraction （XRD） analyses indicate that the products exhibit a hexagonal structure. Scanning electron （SEM）...Uniform CdS colloidal spheres have been successfully synthesized via a simple hydrothermal method. X-ray diffraction （XRD） analyses indicate that the products exhibit a hexagonal structure. Scanning electron （SEM） and transmission electron microscopy （TEM） are used to characterize CdS colloidal spheres. The final size of the spheres may be selected from a range of 71± 2 nm to approximately 181 ± 5 nm by changing the amount of polyvinylpyrrolidone （PVP） and hexamethylenetetramine （HMT）. The CdS colloidal spheres are not obtained in the absence of either of the capping agents. A synergistic effect between HMT and PVP is proposed to be crucial for the formation of colloidal spheres.展开更多
A highly stretchable plasmonic structure composed of a monolayer array of metal-capped colloidal spheres on an elastomeric substrate has been fabricated using simple and inexpensive self-assembly and transfer-printing...A highly stretchable plasmonic structure composed of a monolayer array of metal-capped colloidal spheres on an elastomeric substrate has been fabricated using simple and inexpensive self-assembly and transfer-printing techniques.This composite structure supports coupled surface plasmons whose wavelengths are sensitive to the arrangement of the metal-capped colloidal spheres.Upon stretching,the lattice of metal-capped colloidal spheres will be deformed,leading to a large wavelength shift of surface plasmon resonances and simultaneously an obvious color change.This stretchable plasmonic structure offers a promising approach to tune surface plasmon resonances and might be exploited in realizing flexible plasmonic devices with tunability of mechanical strain.展开更多
A novel copper-mediated solvothermal method was proposed for synthesizing colloidal spheres of a new composition, palladium iodide （PdI2）. Typical procedure was designed to involve the introduction of cupric chlori...A novel copper-mediated solvothermal method was proposed for synthesizing colloidal spheres of a new composition, palladium iodide （PdI2）. Typical procedure was designed to involve the introduction of cupric chloride （CuCI2） as weak oxidant. CuCI2 was found to be essential for preventing the easy formation of palladium deposits as well as facilitating the synthesis and assembly. Under the co-effect of CuC12 and the surfactant of polyvinylpyrrolidone （PVP）, neutral PdI2 colloidal spheres with narrow size distribution were successfully produced. Such ion-assisted synthetic method is believed to be prospective in producing well-constructed nanostructures.展开更多
A surfactant-assisted method for preparing colloidal spheres with narrow size distribution from a polydispersed azo polymer has been developed in this work. The colloidal spheres were formed through gradual hydrophobi...A surfactant-assisted method for preparing colloidal spheres with narrow size distribution from a polydispersed azo polymer has been developed in this work. The colloidal spheres were formed through gradual hydrophobic aggregation of the polymeric chains in THF-H2O dispersion media, which was induced by a steady increase in the water content. Results showed that the addition of a small amount of surfactant （SDBS） could significantly narrow the size distribution of the colloidal spheres. The size distribution of the colloidal spheres was determined by the concentrations of azo polymer and the amount of surfactant in the systems. When the concentrations of polymer and surfactant amount were in a proper range, colloidal spheres with narrow size distribution could be obtained. The colloidal spheres formed by this method could be elongated along the polarization direction of the laser beams to be a new type of the colloid-based functional materials. upon Ar^＋ laser irradiation. The colloidal spheres are considered展开更多
We investigate the transport properties and mechanical response of glassy hard disks using nonlinear Langevin equation theory.We derive expressions for the elastic shear modulus and viscosity in two dimensions on the ...We investigate the transport properties and mechanical response of glassy hard disks using nonlinear Langevin equation theory.We derive expressions for the elastic shear modulus and viscosity in two dimensions on the basis of thermalactivated barrier-hopping dynamics and mechanically accelerated motion.Dense hard disks exhibit phenomena such as softening elasticity,shear-thinning of viscosity,and yielding upon deformation,which are qualitatively similar to dense hard-sphere colloidal suspensions in three dimensions.These phenomena can be ascribed to stress-induced ＂landscape tilting＂.Quantitative comparisons of these phenomena between hard disks and hard spheres are presented.Interestingly,we find that the density dependence of yield stress in hard disks is much more significant than in hard spheres.Our work provides a foundation for further generalizing the nonlinear Langevin equation theory to address slow dynamics and rheological behavior in binary or polydisperse mixtures of hard or soft disks.展开更多
An enhanced KR-fundamental measure functional （FMF） is elaborated and employed to investigate binary and ternary hard sphere fluids near a planar hard wall or confined within two planar hard walls separated by certa...An enhanced KR-fundamental measure functional （FMF） is elaborated and employed to investigate binary and ternary hard sphere fluids near a planar hard wall or confined within two planar hard walls separated by certain interval. The present enhanced KR-FMF incorporates respectively, for aim of comparison, a recent 3rd-order expansion equation of state （EOS） and a Boublfk＇s extension of Kolafa＇s EOS for HS mixtures. It is indicated that the two versions of the EOS lead to, in the framework of the enhanced KR-FMF, similar density profiles, but the 3rd-order EOS is more consistent with an exact scaled particle theory （SPT） relation than the BK EOS. Extensive comparison between the enhanced KR-FMF-3rd-order EOS predictions and corresponding density profiles produced in different periods indicates the excellent performance of the present enhanced KR-FMF-3rd-order EOS in comparison with other available density functional approximations （DFAs）. There are two anomalous situations from whose density profiles all DFAs studied deviate significantly; however, subsequent new computer simulation results for state conditions similar to the two anomalous situations are in very excellent agreement with the present enhanced KR-FMF-3rd-order EOS. The present paper indicates that （i） the validity of the ＂naive＂ substitution elaborated in the present paper and peculiar to the original KR-FMF is still in operation even if inhomogeneoas mixtures are being dealt with; （ii） the high accuracy and self-consistency of the third order EOS seem to allow for application of the KR-FMF-third order EOS to more severe state conditions; and （iii） the ＂naive＂ substitution enables very easy the combination of the original KR-FMF with future＇s more accurate but potentially more complicated EOS of hard sphere mixtures.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
We realized the desired spheroidizing of NiCo_2O_4 nanomaterials by laser irradiating NiCo_2O_4 suspensions with different concentrations. The results reveal that the as-prepared samples are desired spheres with the m...We realized the desired spheroidizing of NiCo_2O_4 nanomaterials by laser irradiating NiCo_2O_4 suspensions with different concentrations. The results reveal that the as-prepared samples are desired spheres with the maximal average size of 568 nm and the superior dispersity, which were obtained at the energy density of 0.30 J·pulse^(-1)·cm^(-2) and NiCo_2O_4 suspension concentration of 0.2 mg·mL^(-1). However, the phase segregation, which was induced by large amounts of solid redox of Co^(3+)/Co^(2+) and Ni^(3+)/Ni^(2+), also appears in the laser-irradiation process.展开更多
基金the National Natural Science Foundation of China(No.21901007)the Natural Science Foundation of Anhui Province(No.2008085QB83)+1 种基金the Science and Technology Development Fund(FDCT)of Macao SAR(No.0032/2021/ITP)the University of Macao(No.MYRG2020-00026-FST)。
文摘Selective hydrogenation of the carbonyl bond inα,β-unsaturated carbonyl compounds is rather challenging owing to the more feasible hydrogenation of ethylenic bond from both thermodynamic and kinetic aspects.Here,we demonstrate a facile emulsionbased molecule-nanoparticle self-assembly strategy for the atomic engineering of Ir species on three-dimensional CeO_(2)spheres(Ir1@CeO_(2)).When applied to the hydrogenation ofα,β-unsaturated aldehydes,Ir1@CeO_(2)catalyst remarkably exhibited~100%selectivity towards unsaturated alcohols,whereas the formation of Ir nanoparticles on CeO_(2)drastically decreased the selectivity for unsaturated alcohols.Spectroscopic studies revealed that strong metal-support interactions triggered the charge transfer from Ir to CeO_(2),leading to the partial reduction of Ce^(4+)to Ce^(3+)along with the formation new Ir^(δ+)-O_(2)--Ce^(3+)(OV)interfaces.The electrophilic atomic Ir species at the Ir^(δ+)-O_(2)--Ce^(3+)(OV)interfaces would therefore preferentially adsorb and facilitate hydrogenation of polar C=O bond to achieve exceptional selectivity.
基金supported by the National Natural Science Foundation of China(Nos.50972080 and 91127017)the National Basic Research Program(No.2009CB930101)the Key Laboratory of Photochemical Conversion and Optoelectronic Materials,TIPC,CAS
文摘Uniform CdS colloidal spheres have been successfully synthesized via a simple hydrothermal method. X-ray diffraction （XRD） analyses indicate that the products exhibit a hexagonal structure. Scanning electron （SEM） and transmission electron microscopy （TEM） are used to characterize CdS colloidal spheres. The final size of the spheres may be selected from a range of 71± 2 nm to approximately 181 ± 5 nm by changing the amount of polyvinylpyrrolidone （PVP） and hexamethylenetetramine （HMT）. The CdS colloidal spheres are not obtained in the absence of either of the capping agents. A synergistic effect between HMT and PVP is proposed to be crucial for the formation of colloidal spheres.
基金This work was supported by the National Program on Key Basic Research Project(973 Program)(Grant Nos.2007CB613200 and 2006CB921700)The research of J.Z.and X.H.L.is further supported by the National Natural Science Foundation of China(NSFC)and the Shanghai Science and Technology Commission.
文摘A highly stretchable plasmonic structure composed of a monolayer array of metal-capped colloidal spheres on an elastomeric substrate has been fabricated using simple and inexpensive self-assembly and transfer-printing techniques.This composite structure supports coupled surface plasmons whose wavelengths are sensitive to the arrangement of the metal-capped colloidal spheres.Upon stretching,the lattice of metal-capped colloidal spheres will be deformed,leading to a large wavelength shift of surface plasmon resonances and simultaneously an obvious color change.This stretchable plasmonic structure offers a promising approach to tune surface plasmon resonances and might be exploited in realizing flexible plasmonic devices with tunability of mechanical strain.
基金supported by the National Basic Program of China for Nanoscience and Nanotechnology (973 Program,2011CB932401)the Foundation for Innovative Research Groups of the National Natural Science Foundation of China (20921001)
文摘A novel copper-mediated solvothermal method was proposed for synthesizing colloidal spheres of a new composition, palladium iodide （PdI2）. Typical procedure was designed to involve the introduction of cupric chloride （CuCI2） as weak oxidant. CuCI2 was found to be essential for preventing the easy formation of palladium deposits as well as facilitating the synthesis and assembly. Under the co-effect of CuC12 and the surfactant of polyvinylpyrrolidone （PVP）, neutral PdI2 colloidal spheres with narrow size distribution were successfully produced. Such ion-assisted synthetic method is believed to be prospective in producing well-constructed nanostructures.
基金The financial support by the NSFC under Projects (Nos. 50533040, 20374033) is gratefully acknowledged.
文摘A surfactant-assisted method for preparing colloidal spheres with narrow size distribution from a polydispersed azo polymer has been developed in this work. The colloidal spheres were formed through gradual hydrophobic aggregation of the polymeric chains in THF-H2O dispersion media, which was induced by a steady increase in the water content. Results showed that the addition of a small amount of surfactant （SDBS） could significantly narrow the size distribution of the colloidal spheres. The size distribution of the colloidal spheres was determined by the concentrations of azo polymer and the amount of surfactant in the systems. When the concentrations of polymer and surfactant amount were in a proper range, colloidal spheres with narrow size distribution could be obtained. The colloidal spheres formed by this method could be elongated along the polarization direction of the laser beams to be a new type of the colloid-based functional materials. upon Ar^＋ laser irradiation. The colloidal spheres are considered
基金Project supported by the National Basic Research Program of China(Grant No.2012CB821500)the National Natural Science Foundation of China(Grant Nos.21374073 and 21574096)
文摘We investigate the transport properties and mechanical response of glassy hard disks using nonlinear Langevin equation theory.We derive expressions for the elastic shear modulus and viscosity in two dimensions on the basis of thermalactivated barrier-hopping dynamics and mechanically accelerated motion.Dense hard disks exhibit phenomena such as softening elasticity,shear-thinning of viscosity,and yielding upon deformation,which are qualitatively similar to dense hard-sphere colloidal suspensions in three dimensions.These phenomena can be ascribed to stress-induced ＂landscape tilting＂.Quantitative comparisons of these phenomena between hard disks and hard spheres are presented.Interestingly,we find that the density dependence of yield stress in hard disks is much more significant than in hard spheres.Our work provides a foundation for further generalizing the nonlinear Langevin equation theory to address slow dynamics and rheological behavior in binary or polydisperse mixtures of hard or soft disks.
基金Supported by the National Natural Science Foundation of China under Grant No.20973202
文摘An enhanced KR-fundamental measure functional （FMF） is elaborated and employed to investigate binary and ternary hard sphere fluids near a planar hard wall or confined within two planar hard walls separated by certain interval. The present enhanced KR-FMF incorporates respectively, for aim of comparison, a recent 3rd-order expansion equation of state （EOS） and a Boublfk＇s extension of Kolafa＇s EOS for HS mixtures. It is indicated that the two versions of the EOS lead to, in the framework of the enhanced KR-FMF, similar density profiles, but the 3rd-order EOS is more consistent with an exact scaled particle theory （SPT） relation than the BK EOS. Extensive comparison between the enhanced KR-FMF-3rd-order EOS predictions and corresponding density profiles produced in different periods indicates the excellent performance of the present enhanced KR-FMF-3rd-order EOS in comparison with other available density functional approximations （DFAs）. There are two anomalous situations from whose density profiles all DFAs studied deviate significantly; however, subsequent new computer simulation results for state conditions similar to the two anomalous situations are in very excellent agreement with the present enhanced KR-FMF-3rd-order EOS. The present paper indicates that （i） the validity of the ＂naive＂ substitution elaborated in the present paper and peculiar to the original KR-FMF is still in operation even if inhomogeneoas mixtures are being dealt with; （ii） the high accuracy and self-consistency of the third order EOS seem to allow for application of the KR-FMF-third order EOS to more severe state conditions; and （iii） the ＂naive＂ substitution enables very easy the combination of the original KR-FMF with future＇s more accurate but potentially more complicated EOS of hard sphere mixtures.
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supported by the National Key Basic Research Program of China(No.2014CB931702)the National Natural Science Foundation of China(Nos.51572128 and 11502116)+1 种基金the National Natural Science Foundation of China and the Research Grants Council(No.5151101197)the Priority Academic Program Development of Jiangsu Higher Education Institutions
文摘We realized the desired spheroidizing of NiCo_2O_4 nanomaterials by laser irradiating NiCo_2O_4 suspensions with different concentrations. The results reveal that the as-prepared samples are desired spheres with the maximal average size of 568 nm and the superior dispersity, which were obtained at the energy density of 0.30 J·pulse^(-1)·cm^(-2) and NiCo_2O_4 suspension concentration of 0.2 mg·mL^(-1). However, the phase segregation, which was induced by large amounts of solid redox of Co^(3+)/Co^(2+) and Ni^(3+)/Ni^(2+), also appears in the laser-irradiation process.
