Materials Literature
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A novel triterpene, viburgenin (1), has been isolated from an extract of the ripe fruit rinds of Rudgea viburnioides, together with the known saponins, arjunglucoside I and trachelosperosides B-1 and E-1, and the triterpenes trachelosperogenin B (2) and arjungenin. Compound 2 was previously obtained as a product from…
A tight-band model is employed for the e2g-orbitals in manganites.It is shown that a large intraatomic Hund's coupling, JH and the resulting double-exchange mechanism lead to antiferromagnetic ordering along one of the cubic axis stabilized by the cooperative JT effect which further decreases the band energy of electr…
Uniform magnetic membranes are obtained from microfibrillar bacterial cellulose suspensions loaded with nanosized ferrites (mainly magnetite). The cellulose microfibrils act as a nucleation site for the growing ferrites, as clearly visible by trasmission electron microscopy.
The 2,2'-dipyridyl adducts of two europium beta-diketonate complexes, Eu(btfa)(3).bipy [btfa = 4,4,4-trifluoro-1-phenyl-2,4-butanedione, bipy = 2,2'-dipyridyl] and Eu(bzac)(3).bipy [bzac = 1-phenyl-2,4-butanedione], have been prepared. The crystal structure of the former with chemical formula EuC(40)H(26)O(6)N(2)F(9)…
Assemblies of polymer beads were used as templates to produce macroporous membranes of polymers and ceramics. These membranes consist of spherical pores whose sizes could be precisely controlled in the range from ∼0.2 to ∼3 μm. The pores are interconnected such that pores (as many as 108/cm2) are completely exposed on…
A detailed numerical and experimental study of the ordering of the low temperature tetragonal phase of CuAu is presented. The numerical simulations are based on a coarse-grained free energy derived from electronic structure calculations of CuAu, while the experimental results are obtained from in situ x-ray scattering…
The preparation and chemical reactivity of Ag@SiO 2 particles have been investigated using UV−vis spectroscopy, laser Doppler electrophoresis, and electron microscopy. The factors governing the deposition of silica onto silane-primed silver particles have been investigated and the deposition conditions (pH and reagent…
PURPOSE: Dental casting requires replication of complex shapes with high fidelity. To achieve this objective, the problem of scale formation on titanium dental castings must be overcome. Scaling occurs readily at high temperatures because of the high reactivity of molten titanium with investment materials. The purpose…
Transition-metal-containing analogues of a polymerizable lyotropic liquid crystal were prepared from sodium p -styryloctadecanoate by ion exchange with water-soluble metal chlorides, nitrates, and acetates. The mesophases of these amphiphilic monomers were investigated by polarized light microscopy, low-angle X-ray di…
Folylpolyglutamate synthetase, which is responsible for the addition of a polyglutamate tail to folate and folate derivatives, is an ATP-dependent enzyme isolated from eukaryotic and bacterial sources, where it plays a key role in the retention of the intracellular folate pool. Here, we report the 2.4-A resolution cry…
The template method for preparing nanomaterials entails synthesis of the desired material within the pores of a microporous membrane. Monodisperse tubules and fibrils of the desired material are obtained. Procedures for preparing colloidal suspensions of template-synthesized polypyrrole nanotubules are described here.
The abilities of electropolymerized films formed from various substituted naphthalenes to prevent the oxidation of the plasma interferences ascorbate, acetaminophen, and urate at a hydrogen peroxide detecting platinum electrode are reported. Films prepared from 2,3-, 1,5-, and 1,8-diaminonaphthalene and 5-amino-1-naph…
To realize a trivalent ion conduction in solids, the Sc 2 (WO 4 ) 3 -type structure was chosen on the basis of the mobile trivalent ions and the structure which reduces the electrostatic interaction between the framework and the mobile trivalent ionic species as much as possible. The typical conductivity of the rare e…
The specular reflectivity of lamellar gratings of gold with grooves 0.5 microns wide separated by a distance of 3.5 microns was measured on the 2000 cm$^{-1}$ - 7000 cm$^{-1}$ spectral range for p-polarized light. For the first time, experimental evidence of the excitation of electromagnetic surface shape resonances f…
Compact directed percolation is known to appear at the endpoint of the directed percolation critical line of the Domany-Kinzel cellular automaton in 1+1 dimension. Equivalently, such transition occurs at zero temperature in a magnetic field H, upon changing the sign of H, in the one-dimensional Glauber-Ising model wit…
With the aim of identifying universal trends, we compare fully self-consistent electronic spectra and total energies obtained from the GW approximation with those from an extended GWGamma scheme that includes a nontrivial vertex function and the fundamentally distinct Bethe-Goldstone approach based on the T-matrix. Th…
we investigate developable cones (d-cones) topology and mechanical properties. We found that for a sample of a finite thickness the singularity is never pointlike but has a spatial extension in form of a crescent. The variations of the sheet local curvature versus the distance from the d-cone tip for all deformations…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTHeterogeneous Catalysts for Liquid-Phase Oxidations: Philosophers' Stones or Trojan Horses?Roger A. Sheldon, Martin Wallau, Isabel W. C. E. Arends, and Ulf SchuchardtView Author Information Laboratory of Organic Chemistry and Catalysis, Delft University of Technology, Julian…
When a mixture of two viscous liquids flows past a solid wall there is an ambiguity in the use of the no-slip boundary condition. It is not obvious whether the mass-averaged velocity, the volume-averaged velocity, the individual species velocities, all of the above, or none of the above should exhibit no slip. Extensi…
Highly (110)-oriented and (100) nearly epitaxial 0.7PMN-0.3PT thin films were deposited on (1012) sapphire and (100) LaAlO3 substrates, respectively, using a dip-coating method. Optical waveguide characterization and electro-optic effect measurements of the film on sapphire substrate were demonstrated. Low propagation…