Materials Literature
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Interparticle interaction and structure of glycogen from a shell fish (mussels) were studied in water and 0.5 N NaOH by static and dynamic light scattering and viscometry. A concentration regime up to 30% w/v was covered. Beyond the overlap concentration a large-scale clustering was observed which was interpreted as a…
The [P 2 W 18 M 6 S 6 O 74 (H 2 O) 6 ] 12 - anions, M = Mo, W, were obtained through the stereospecific addition of the dithiocation [M 2 O 2 S 2 ] 2+ to the trivacant A-α-[PW 9 O 34 ] 9 - . K 12 [P 2 W 18 Mo 6 S 6 O 74 (H 2 O) 6 ]·26H 2 O has been isolated as crystals and has been characterized by X-ray diffraction (…
In this paper we describe an experimental procedure that can be used to study the photoreduction of metal ions on the surfaces of individual TiO 2 particles. The submicrometer-sized particles are isolated on porous membranes, characterized by atomic force microscopy (AFM), removed from the microscope, exposed to AgNO…
An azocarbazole-based polyimide was synthesized from an azocarbazole diamine monomer and 4,4‘-(hexafluoroisopropylidene)diphthalic anhydride (6FDA) by a two-step polycondensation reaction. Birefringence experiments have been performed on the pure polyimide and on the polyimide mixed with small azo chromophores. Becaus…
A chemically prepared emeraldine chloride powder has been studied by high-resolution electron microscopy. Two kinds of grains with varying degrees of crystallinity were observed: (i) Rolled sheets (20−100 nm in diameter) (aggregates, disks, or ribbons?) with an amorphous surface layer are identified as the EB-II polym…
The acid-catalyzed condensation of 4-hydroxyphenylmethyl ketone (p-hydroxyacetophenone) with pyrrole affords a new type of calix[4]pyrrole derivative that contains deep cavities and fixed walls. These new systems, which can be readily converted into the corresponding 4-methoxyphenyl species, can exist in the form of f…
Catalytically grown graphite nanofibers (GNF) are molecularly engineered structures that are produced by the interaction of carbon-containing gases with small metal particles at temperatures around 600 °C. The fibrous solids consist of minuscule graphene sheets stacked at various angles with respect to the fiber axis.…
We calculate the value of the Fröhlich electron-phonon interaction in manganites, cuprates, and some other charge-transfer insulators and show that this interaction is much stronger than any relevant magnetic interaction. A polaron shift due to the Fröhlich interaction, which is about 1 eV, suggests that carriers in t…
This is a short review of the physical ideas,algorithm for the calculation of the phase transition pressure and some results of a semi-classical theory of the behaviour of materials under high pressure proposed by P.Savic and R.Kasanin.It is base on the Coulomb interaction,supplemented by a microscopic selection rule…
A mechanism of the parity effect in the thermally assisted resonant tunneling is proposed in the view point of nonadiabatic transitions of thermally excited states. In this mechanism, alternating enhancement of the relaxation is naturally understood as a general property of quantum relaxation of uniaxial magnets at fi…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTNiobium Compounds: Preparation, Characterization, and Application in Heterogeneous CatalysisIzabela Nowak and Maria ZiolekView Author Information A. Mickiewicz University, Faculty of Chemistry, Grunwaldzka 6, 60-780 Poznan, Poland Cite this: Chem. Rev. 1999, 99, 12, 3603–362…
Brewster angle microscopy, interfacial stress rheometry, and Π− A isotherm measurements are employed to characterize spread monolayers of two new cellulose derivatives, one containing octadecyl side chains, the other p -nitroaniline substituents. Similar monolayer phase behavior is found in both cases. At high surface…
The electronic and geometrical structures of the ground states and low-lying isomers of MnO 4 and MnO 4 - have been calculated as a function of spin-multiplicities by using the molecular orbital theory based on generalized gradient approximation to the density functional formalism. Total energies of isomers are used f…
A general design strategy for the synthesis of cystine-based peptide nanotubes is described. The design essentially involves closing of the polymethylene chains with cystine diOMe. The cystine-based nanotubes are constructed by the self-assembly of a simple cyclobisamide building block, a key structural feature of whi…
Static and MAS 207 Pb NMR spectra of a series of lead oxides, including the electronic materials PbTiO 3 (PT), PbZrO 3, Pb(Zr 0.53 Ti 0.47 )O 3, Pb(Mg 0.33 Nb 0.67 )O 3 (PMN), and 0.66PMN/0.34PT, have been measured. The chemical shift parameters (δ iso, δ aniso, and η) and the spin−lattice relaxation times have been d…
The full details of synthesis and characterization of diiron(III)-substituted γ-Keggin silicotungstate, [γ(1,2)-SiW 10 {Fe(OH 2 )} 2 O 38 ] 6 - (abbreviated as I ) were reported. This complex was synthesized by the reaction of the lacunary [γ-SiW 10 O 36 ] 8 - with Fe(NO 3 ) 3 in an acidic aqueous solution and isolate…
SERS spectra of phenazine adsorbed on silver colloids have been investigated. For ligand concentrations from 10 -4 to 10 -6 M, it was possible to obtain the adsorption isotherm of phenazine by absorption measurements in the UV−visible region. Filtration of the ligand/hydrosol systems through suitable filters containin…
Optical absorption spectra of InSe and InSe:Er single crystals were investigated just below and in the excitonic resonance energy region. The temperature dependence of the free exciton transition associated with the direct gap of InSe and InSe:Er were measured in the temperature range 10< T <340 K. The parameters desc…
Impulse breakdown of a point/plane gap in mixtures of SF 6 with selected buffer gases (air, CO 2 and N 2 ) has been studied. It has been found that the minimum impulse breakdown voltage of these SF 6 mixtures can be higher than or comparable with that of pure SF 6 . This finding is discussed in terms of the change of…
Chromium oxide pillared manganese oxide materials were prepared by intercalating layered manganese oxide with chromium hydroxyl acetate clusters under reflux condition. The as-synthesized materials were heated at 200 °C in flowing nitrogen for 1 h to result in chromium oxide pillared manganese oxides. X-ray diffractio…