Materials Literature
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Poly(propylene imine) dendrimers that are modified with long alkyl chains self-assemble to form well-defined aggregates. The geometry and surface chemistry of the dendrimer assemblies can be varied through the addition of surfactants. These dendrimer/surfactant aggregates can be tuned to template the formation of the…
Contrast agent for magnetic resonance imaging: The exchangeable amide protons in the Yb3+ complex of 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetamide (see crystal structure) act as efficient antennae for transfer of saturated spins to bulk water. Saturation of all eight protons in a 5 mM solution of this complex…
Durch chemische Funktionalisierung einwandiger Kohlenstoffnanoröhren werden die Voraussetzungen für mögliche Anwendungen solcher Nanostrukturen geschaffen. Derivatisierte Röhren zeichnen sich im Unterschied zum Rohmaterial u. a. durch eine gute Löslichkeit aus und sind so einer umfangreichen Charakterisierung und Folg…
We have investigated the change of atomic and electronic structures of fluorinated single-walled carbon nanotubes (SWCNTs) using x-ray photoemission spectroscopy (XPS), electrical resistivity measurements, and transmission electron microscopy (TEM). The fluorine content increases with increasing reaction temperature u…
Low-spin, high-spin and spin-transition behaviours have been observed for the doubly interpenetrating three-dimensional bimetallic compounds (FeII(pz)[Ag(CN)2]2).pz (pz = pyrazine), (FeII(4,4'-bipy)2[Ag(CN)2]2) (4,4'-bipy = 4,4'-bipyridine), and (FeII(bpe)2[Ag(CN)2]2) (bpe = bispyridylethylene), respectively. The sing…
We report on the discovery of a room-temperature ferromagnetism in Cr-doped GaN single crystals with a Tc=280 K. The addition of Cr into GaN single crystals grown by the flux method induces the lattice constant increase due to the larger Cr atomic radius. In x-ray photoelectron spectroscopy measurement, Cr 2p3/2 core-…
Nanocrystals of magnesium oxide react with organophosphorus compounds at room temperature by dissociative chemisorption, which we term "destructive adsorption". This process involves cleavage of P-O and P-F bonds (but not P-C bonds) and immobilization of the resultant molecular fragments. These ultrafine powders have…
Dendritic multichromophores based on a rigid polyphenylene scaffold contain up to three different types of rylene chromophores incorporated at the focal point, the scaffold, and the periphery of the dendrimer. An energy gradient between the periphery and the core is thus generated and allows an efficient transfer of e…
For forty years researchers on ferroelectric switching have used the Kay-Dunn theory to model the thickness-dependence of the coercive field; it works surprisingly well, despite the fact that it is based upon homogeneous nucleation and a small-field expansion, neither of which is realized in thin films. Here we demons…
Fine metal nanoparticles of Ag, Au, Pd, and Pt were obtained at room temperature, by simple mixing of the corresponding metal ions with reduced polyoxometalates (POMs) that serve both as photocatalysts and stabilizers, according to the cycle shown.
The microstructure is appealing: Onion-like carbon forms are used for the first time in the field of catalysis and thus open new routes for the potential applications of nonplanar carbon materials. An example is given with the oxidative dehydrogenation of ethylbenzene to styrene (see scheme).
Fine metal nanoparticles of Ag, Au, Pd, and Pt were obtained at room temperature, by simple mixing of the corresponding metal ions with reduced polyoxometalates (POMs) that serve both as photocatalysts and stabilizers, according to the cycle shown.
The magnetic behavior of insulating doped diluted magnetic semiconductors (DMS's) is characterized by the interaction of large collective spins known as bound magnetic polarons. Experimental measurements of the susceptibility of these materials have suggested that the polaron-polaron interaction is ferromagnetic, in c…
Using a laser tweezers method, we have determined the long-range repulsive force as a function of separation between two charged, spherical polystyrene particles (2.7 microm diameter) present at a nonpolar oil-water interface. At large separations (6 to 12 microm between particle centers) the force is found to decay w…
Abstract A novel cellulose solvent, 1.5 M NaOH/0.65 M thiourea aqueous solution, was used to dissolve cotton linters having a molecular weight of 10.1 × 10 4 to prepare cellulose solution. Regenerated cellulose (RC) films were obtained from the cellulose solution by coagulating with sulfuric acid (H 2 SO 4 ) aqueous s…
We report metalorganic vapor-phase epitaxial growth and structural and photoluminescent characteristics of ZnO nanorods. The nanorods were grown on Al2O3(00⋅1) substrates at 400 °C without employing any metal catalysts usually needed in other methods. Electron microscopy revealed that nanorods with uniform distributio…
Through chemical functionalization of single-walled carbon nanotubes, the prerequisites for possible applications of such nanostructures are established. The derivatized tubes differ from the crude materials in their good solubility, which enables both a more extensive characterization and subsequent chemical reactivi…
According to recent insights, the phytoplankton of the eastern Adriatic Sea is composed of 888 determined species. The diatoms were composed of 518 species (330 pennates, 176 centric diatoms), dinoflagellates 254, prymnesiophyceae101, chrysophyceae 2, raphidophyceae 1 and euglenophyceae 2 species. The list is accompan…
Abstract The solubility of diuron (3‐(3,4‐dichlorophenyl)‐1, 1 ‐dimethyl urea) and monuron (3‐(4‐chlorophenyl)‐1, 1 ‐dimethyl urea) in 49 and 43 different organic non‐electrolyte solvents, respectively, have been calculated. It was found that Modified UNIFAC described well the solubilities both in polar solvents like…
A região de Piraju -- SP é caracterizada geologicamente por apresentar uma grande distribuição de rochas básicas e ácidas da Formação Serra Geral. Os processos e produtos de alteração das rochas básicas são apresentados em muitos trabalhos, mas estudos envolvendo alteração de rochas vulcânicas ácidas são raros. Aprese…