About Dendrimers: Structure, Physical Properties, and Applications
No abstract
Materials Literature
文献浏览
按标题、摘要、年份、主题和来源检索公开元数据。结果保留作者、摘要、分类与原始来源链接。
Size and Temperature Dependence of the Plasmon Absorption of Colloidal Gold Nanoparticles
The size and temperature dependence of the plasmon absorption is studied for 9, 15, 22, 48, and 99 nm gold nanoparticles in aqueous solution. The plasmon bandwidth is found to follow the predicted behavior as it increases with decreasing size in the intrinsic size region (mean diameter smaller than 25 nm), and also in…
Nanotubes from Carbon
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTNanotubes from CarbonP. M. AjayanView Author Information Department of Materials Science & Engineering, Rensselaer Polytechnic Institute, Troy, New York 12180-3590 Cite this: Chem. Rev. 1999, 99, 7, 1787–1800Publication Date (Web):May 1, 1999Publication History Received29 Ju…
Electron density and traditional structural chemistry of silicates
New rezults of studies on the electron density of silicates are considered in accordance with the traditional structural classification. Precision X-ray diffraction data and rezults of structure refinement based on high-angle and multipole models are discussed. Bonded radii, charges on anoms and bond ionicities in Si,…
Design, Synthesis, and Characterization of Tyrosinophanes, a Novel Family of Aromatic-Bridged Tyrosine-Based Cyclodepsipeptides
A simple two-step design strategy has been developed for the synthesis of a large variety of a new class of tyrosine-based aromatic (Ph or Pyr) bridged cyclodepsipeptides (tyrosinophanes). The design is flexible with respect to the size of the ring and the nature of the bridging unit and permits the incorporation of a…
A suitable low-order, tetrahedral finite element for solids
To use the all-tetrahedral mesh generation capabilities existing today, we have explored the creation of a computationally efficient eight-node tetrahedral finite element (a four-node tetrahedral finite element enriched with four mid-face nodal points). The derivation of the element's gradient operator, studies in obt…
Mass spectrometric characterization of polyhedral oligosilsesquioxanes and heterosilsesquioxanes
Silsesquioxanes constitute a diverse range of Si-O frameworks with a wide variety of intriguing possibilities as models for catalysis. These topologically interesting molecules are formed by the hydrolytic condensation of trifunctional organosilanes. Heterosilsesquioxanes are formally derived by substitution of a main…
The effect of strong intermolecular and chemical interactions on the compatibility of polymers
The data on compatibility and on the properties of polymer blends are generalised. The emphasis is placed on the formation of strong intermolecular interactions (dipole–dipole interaction and hydrogen bonding) between the components of blends, as well as on the chemical reactions between them. A criterion for the pred…
Surface Pressure and Surface Potential Isotherms of Ytterbium Bisphthalocyanine Langmuir Monolayers
A systematic study is reported on the monolayer characteristics of ytterbium bisphthalocyanine (YbPc 2 ) at the air−water interface, using surface pressure and surface potential isotherms. The influence of various experimental parameters was analyzed, including compression speed, spreading volume, position of the pres…
Morphology−Interface−Property Relationships in Polystyrene/Ethylene−Propylene Rubber Blends. 2. Influence of Areal Density and Interfacial Saturation of Diblock and Triblock Copolymer Interfacial Modifiers
An emulsification curve which tracks the change in dispersed phase size with interfacial modifier concentration and a fracture mechanics approach have been used to study the behavior of a variety of well-defined interfacial modifiers for a melt-processed ethylene−propylene rubber (EPR)/polystyrene (PS) blend. In this…
Femtosecond Time-Resolved Dynamics of Geminate and Nongeminate Recombination: Iodine Enclosed in the Nanocavities of a Microporous SiO2 Modification
In this study, we report the ultrafast dissociation and recombination dynamics of I 2 enclosed in well-defined cages formed by the electroneutral host framework of the crystalline microporous SiO 2 modification decadodecasil 3R (DDR). In this composite, each cage is occupied by one guest molecule, corresponding to a h…
STRUCTURE AND DEBYE TEMPERATURE OF WURTZITE GaN
High Pure Wurtzite structure GaN has been synthesized by gas reaction method. Its structure was determined by powder X-ray diffraction using the Rietveld technique. The positions in the unit cell for Ga and N were refined to be (0, 0, 0) and (0, 0, 0.3814). The Debye temperature was determined as 586 K from the refine…
An Increasing Correlation Length in Off-Equilibrium Glasses
In off-equilibrium dynamics we define a dynamical correlation length that is proportional to the size of the region in which the atoms move in a correlated way. General arguments indicate that this dynamical correlation length diverges at large times in the glassy phase. Numerical simulations for binary mixtures are c…
Vinyl-Substituted Silphenylene Siloxane Copolymers: Novel High-Temperature Elastomers
The synthesis of a series of vinyl-substituted silphenylene siloxane polymers of high molecular weight is described. 29 Si NMR spectroscopy indicates that the polymers possess an exactly alternating microstructure of the silphenylene and siloxane moieties. The materials are completely amorphous with glass transition t…
Regio- and Diastereoselective Catalytic Epoxidation of Acyclic Allylic Alcohols with Methyltrioxorhenium: A Mechanistic Comparison with Metal (Peroxy and Peroxo Complexes) and Nonmetal (Peracids and Dioxirane) Oxidants
Geraniol and its 1-methyl derivative (regiochemical probes) and a set of methyl- and tert-butyl-substituted chiral allylic alcohols (stereochemical probes) have been used to elucidate the mechanism of the MTO-catalyzed epoxidation of allylic alcohols. The regiochemical probes are preferentially epoxidized at the unfun…
First Quaternary A−Pb−Bi−Q (A = K, Rb, Cs; Q = S, Se) Compounds: Synthesis, Structure, and Properties of α- and β-CsPbBi3Se6, APbBi3Se6, (A = K, Rb), and APbBi3S6 (A = Rb, Cs)
α-CsPbBi 3 Se 6 ( I ), β-CsPbBi 3 Se 6 ( II ), RbPbBi 3 Se 6 ( III ), KPbBi 3 Se 6 ( IV ), CsPbBi 3 S 6 ( V ), and RbPbBi 3 S 6 ( VI ) were synthesized by the polychalcogenide flux method. α-CsPbBi 3 Se 6 was obtained at 720 °C and crystallizes in the space group Pnma (no. 62) with a = 23.564(6) Å, b = 4.210(2) Å, c =…
Structural Characterization of Lactate Dehydrogenase Dissociation under High Pressure Studied by Synchrotron High-Pressure Small-Angle X-ray Scattering
The effect of high pressure on lactate dehydrogenase (LDH) was studied using small-angle X-ray scattering (SAXS). The SAXS results are interpreted in terms of the dissociation and association of LDH within a compression and decompression cycle and its temperature dependence. LDH consists of four identical subunits. At…
Multiphoton-Excited Luminescence from Diamond Nanoparticles
The highly efficient photoluminescence (PL) from diamond nanoparticles of different size (diameter) D = 5, 100, 400, 700, and 1000 nm was observed. The PL was induced by laser pulsed ultraviolet (UV) light [λ exc = 354.7 nm (3.48 eV), τ = 10 ns] as well as by the infrared (IR) one [λ exc = 1064 nm (1.16 eV), τ = 10 ns…
Interaction of D2O with CeO2(001) Investigated by Temperature-Programmed Desorption and X-ray Photoelectron Spectroscopy
The interaction of D 2 O with the CeO 2 (001) surface was studied with temperature-programmed desorption (TPD) and X-ray photoelectron spectroscopy (XPS). It was found with TPD that D 2 O desorption occurs in three states with temperatures of 152, 200, and 275 K, which are defined as multilayer D 2 O, weakly bound sur…
Surface Micellar Nanopattern Formation of Adsorbed Diblock Copolymer Systems
In this paper, we investigate theoretically the structure of an ultrathin layer of diblock copolymers. It is assumed that one of the blocks is strongly adsorbed on a planar surface while the nonadsorbed block aggregates with the formation of surface micelles. We adopt a simple model in which the adsorbed blocks of the…