Materials Literature
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Laser-arc evaporation of a graphite target has been used to deposit carbon films that exhibit high hardness (45 GPa) and elastic recovery (85%). High-resolution electron microscopy (HREM) and electron energy loss spectroscopy (EELS) were subsequently used to study the microstructure and bonding of the resultant layers…
The low-temperature spin dynamics of doped manganites have been analyzed within a tight-binding model, the parameters of which are estimated by mapping the results of ab initio density-functional calculations onto the model. This approach is found to provide a good description of the spin dynamics of the doped mangani…
Distortions of the oxygen sublattice couple to ${e}_{g}$ orbitals of ${\mathrm{Mn}}^{3+}$ and drive a cooperative Jahn-Teller (orbital ordering) transition in ${\mathrm{LaMnO}}_{3}.$ A simple model for this transition is studied. Without further adjustment, the model predicts the shape and stability of small (anti-Jah…
Uniform microcrystalline nickel(II) hydroxide particles have been prepared via the homogeneous alkalinization of nickel(II) nitrate solutions by urea hydrolysis. The nature of the precipitated solids depends on the temperature of synthesis. At ca. 423 K, i.e., under the hydrothermal conditions attained by microwave he…
We provide a straightforward and efficient procedure to combine the local density approximation plus Hubbard U (LDA+U) total-energy functional with the full-potential linearized augmented plane-wave method. A detailed derivation of the LDA+U Kohn-Sham-type equations is presented for the augmented plane-wave basis set,…
The presence of a large permanent dipole moment has important implications on our understanding of nanocrystalline materials. We report the results of dielectric dispersion studies of CdSe, ZnSe, and metal nanocrystals. Due to the polar nature of the wurtzite lattice, a permanent dipole moment may be expected for CdSe…
We fabricated a two-dimensional subwavelength structured (SWS) surface upon a crystal silicon substrate. The SWS surface was patterned by electron beam lithography and etched by an SF(6) fast atom beam. The SWS grating had a conical profile, the period was 150 nm, and the groove was approximately 350 nm deep. The refl…
Melts of ABA triblock copolymer molecules with identical end blocks are examined using self-consistent field theory (SCFT). Phase diagrams are calculated and compared with those of homologous AB diblock copolymers formed by snipping the triblocks in half. This creates additional end segments which decreases the degree…
The role of the metal-oxide interface in determining the spin polarization of electrons tunneling from or into ferromagnetic transition metals in magnetic tunnel junctions is reported. The spin polarization of cobalt in tunnel junctions with an alumina barrier is positive, but it is negative when the barrier is stront…
It is generally accepted that iron is the most important micronutrient used by bacteria. With members of the family Lactobacillae being the only exceptions so far (3), this metal is essential for cellular metabolism, since it is needed as a cofactor for a large number of enzymes (96). However, this element is not easi…
Experimental solubilities are reported for anthracene dissolved in ternary dibutyl ether + 1-propanol + 2,2,4-trimethylpentane, dibutyl ether + 2-propanol + 2,2,4-trimethylpentane, dibutyl ether + 1-butanol + 2,2,4-trimethylpentane, dibutyl ether + 2-butanol + 2,2,4-trimethylpentane, and dibutyl ether + 2-methyl-1-pro…
The surface-enhanced Raman scattering (SERS) intensities for ethanethiol adsorbed on a silver island film have been measured for a variety of annealing conditions over the 15−300 K temperature range. Reversible temperature dependence of the C−S stretching intensities for an unannealed film similar to the case of 1-pro…
The localized-density-matrix method (Yokojima, S.; Chen, G. H. Chem. Phys. Lett . 1998, 292, 379) is employed to simulate the optical responses of very large carbon nanotubes and polyacetylene oligomers containing 10 000 carbon atoms. The Pariser−Parr−Pople Hamiltonian is used to describe the π electrons in these syst…
4,4′-(Hexafluoroisopropylidene)-bis-(phthalic anhydride) (1) was reacted with L-leucine (2) in toluene solution at refluxing temperature in the presence of triethylamine and the resulting imide-acid (4) was obtained in quantitative yield. The compound (4) was converted to the diacid chloride (5) by reaction with thion…
The relationship between the porous texture, the coordination number of Al atoms, the type of surface acidity, and the sol−gel acidic synthesis conditions at two pH values (pH ≈ 2 and pH ≈ 0), was studied in SiO 2 −Al 2 O 3 aerogels made with a molar Si to Al ratio r Si/Al = 100. The influences of chelation of the Al…
A series of single crystals of quasi-one-dimensional bromo-bridged Ni-Pd mixed-metal MX chain compounds Ni(1)(-)(x)()Pd(x)()(chxn)(2)Br(3) (chxn = 1(R),2(R)-diaminocyclohexane) have been obtained by electrochemical oxidation methods of the mixed methanol solutions of parent Ni(II) complex [Ni(chxn)(2)]Br(2) and Pd(II)…
The contributions to catalysis of the conserved catalytic aspartate (Asp149) in the phosphorylase kinase catalytic subunit (PhK; residues 1-298) have been studied by kinetic and crystallographic methods. Kinetic studies in solvents of different viscosity show that PhK, like cyclic AMP dependent protein kinase, exhibit…
Amine-functionalized thin films were prepared by plasma-induced deposition of allylamine. Radio frequency (rf) plasma polymerization was carried out under both continuous wave (CW) and pulsed conditions to control the film chemistry. The chemical and physical nature of plasma-polymerized allylamine films was investiga…
ADVERTISEMENT RETURN TO ISSUEPREVCommunicationNEXTChalcogen-Rich Lanthanide Clusters from Lanthanide Halide Starting Materials: A New Approach to the Low-Temperature Synthesis of LnSx Solids from Molecular PrecursorsJonathan H. Melman, Mark Fitzgerald, D. Freedman, T. J. Emge, and John G. BrennanView Author Informatio…
The 15 K visible (VIS) upconversion-luminescence of Cs 2 ZrBr 6:0.2% Os 4+ upon excitation in the near-infrared (NIR) is presented and analyzed. Crystals of Cs 2 ZrBr 6:0.2% Os 4+ were synthesized and grown by the Bridgman technique. At 15 K VIS luminescence around 16000 cm - 1 is induced by NIR excitation around 1140…