Materials Literature
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We study the morphology of symmetric diblock copolymer films with thicknesses below the bulk equilibrium period supported by both flat and corrugated substrates. In this thickness regime, the film morphology is characterized by the formation of uniformly sized lateral domains. On flat substrates, these domains are ran…
A method to prepare silicon nitride nanoscale rods using carbon nanotube as a template has been presented in this letter. The products of the reaction of carbon nanotubes with a mixture of Si and SiO2 powder in nitrogen atmosphere are β-Si3N4, α-Si3N4, and Si2N2O nanorods. The sizes of the nanorods are 4–40 nm in diam…
We show theoretically that the purely repulsive screened-Coulomb (or Derjaguin-Landau-Verwey-Overbeek) interaction between charged colloidal particles is compatible with gas-liquid, gas-solid, and solid-solid coexistence in colloidal suspensions of low ionic strength of about ${10}^{\ensuremath{-}6}\mathrm{mol}/\mathr…
We present a simple theory for structural transitions in displacive ferroelectrics of the perovskite type. In our theory, the competition between the elastic energy cost for the displacement of the homopolar ion from the centrosymmetric position, and the energy gain due to a ferroelectric ordering of the dipoles forme…
Durch Einbau von Pyrrolringen gelang die Stabilisierung des größten von Sondheimer et al. synthetisierten Annulens, des [30]Annulens. Von den neuen aromatischen [30]Porphyrinen 1–3 ist das 16‐Phenylderivat 2 am stabilsten. magnified image
Blends of PA 6 with SMA or with 12.5–100% fatty amine (C 18) modified SMA at compositions 95/5–60/40 were studied. Particle size of SMA dispersed in PA 6 matrix was around 0.1 μm due to in situ compatibilizer formation. The strength and stiffness of the blends were higher and toughness unchanged in comparison with PA…
Bovine serum albumin and chicken-egg lsoyzyme can be cleaved with high specificity into two fragments by the method shown below. A pyrene-L-phenylalanine conjugate was used as the probe (shown schematically over the first arrow), which binds with site specificity to the protein and produces the cleavage upon irradiati…
A Velcro-like thin-film composite in which dendrimers acts as burrs and a reactive anhydride copolymer acts like wool (see schematic representation on the right) can be readily prepared from commercially available reagents. Films that are 10–50 nm thick and contain alternating layers of both components were synthesize…
An unusually slow electron transfer takes place in the porphyrinato complex 1 (M = Ni, Zn). The rate of this proton-coupled electron transfer is influenced by a salt bridge in which benzoate ions are bound to the amidinium group, even in solvents with a high dielectric constant, such as DMSO.
Nuggets and threads form upon reduction of gold salts under various reaction conditions in nanometer-sized polymer gel particles (see picture on the right). Due to their structure and resulting elasticity, these microgels create to local reaction environment that, as with biomineralization, favors the production of or…
Employing first principles total energy calculations we have studied the behavior of Ga and Al adatoms on the GaAs(001)-beta2 surface. The adsorption site and two relevant diffusion channels are identified. The channels are characterized by different adatom-surface dimer interaction. Both affect in a novel way the ada…
Montmorillonite (MON) was solvent-cast blended with poly(vinyl alcohol) (PVA) and poly(ethylene oxide) (PEO) using water as cosolvent. The structure and properties of the blend films have been investigated. From small- and wide-angle X-ray scattering measurements of the blends, the silicate layers of MON are found to…
Electron microscopy methods have been used to visualize individual spherical and cylindrical supramolecular dendrimers, providing definitive confirmation of the structures suggested by previous x-ray diffraction analysis that assumed a microsegregated model. These dendrimers are self-assembled, self-organized, and ali…
Infrared microspectroscopy with a high brightness synchrotron source can achieve a spatial resolution approaching the diffraction limit. However, in order to realize this intrinsic source brightness at the specimen location, some care must be taken in designing the optical system. Also, when operating in diffraction l…
First principles calculations based on density functional theory are having an incerasing impact on our understanding of molecule-surface interactions. For example, calculations of the multi-dimensional potential energy surface have provided considerable insight into th edynamics of dissociation processes. However, th…
The Yb atom in the title compound, K[Yb(C10H12N2O8)(H2O)2].5H2O, is eight coordinate through two N and four O atoms in edta, and two water O atoms, where edta denotes ethylenediaminetetraacetate. The geometry around the Yb atom is influenced by the size and electrostatic properties of the counter cations.
Using a nonstandard preparation procedure, porous silicon (PS) samples are grown whose overall photoluminescence (PL) intensities exceed those of standard PS samples from the same Si wafer up to 50 times, and whose PL maxima occur in the high-energy range at about 1.8 eV. The preparation includes an electrochemical et…
Anisotropic and isotropic Sm2Co17-type permanent magnets have been prepared by using the conventional sintering technique. Transmission electron microscopy was used to characterize the cellular structure within the Sm2(Fe,Co)17 grains. Hysteresis loops (M∼H) were measured in the temperature range from 4.2 to about 100…
Crystals of a new nesosilicate, tricalcium diyttrium trisilicon oxide, Ca3Y2(SiO4)3, were prepared from a silicate melt by slow cooling. The structure was refined in space group Pnma and has nine-, eight- and seven-coordinate sites for Ca2+ and Y3+ cations. The structural formula can be expressed as (Ca0.84Y0.16) (Ca0…
An extensive investigation of the fluorescence dynamics of the (2H11/2,4S3/2), 4F9/2, 4I9/2, 4I11/2, and 4I13/2 states was carried out for 0.1%, 1%, 2.5%, and 10% Er3+ doped in YVO4. The decay profiles of the luminescence of the 4S3/2 level of Er3+ (1.0%) obey the Inokuti–Hirayama model for energy transfer for an elec…