Materials Literature
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In this review the double exchange (DE) model forming a basis for the description of the physics of colossal magnetoresistance manganites is discussed. For a limiting case of exchange interaction which is large compared with the band width, the effective Hamiltonian of the DE model is derived from that of the sd-excha…
In ferromagnetic thin films, the Curie temperature variation with the thickness is always considered as continuous when the thickness is varied from $n$ to $n+1$ atomic planes. We show that it is not the case for Fe in Fe/Ir superlattices. For an integer number of atomic planes, a unique magnetic transition is observe…
The high-temperature cubic-tetragonal phase transition of pure stoichiometric zirconia is studied by molecular dynamics (MD) simulations and within the framework of the Landau theory of phase transformations. The interatomic forces are calculated using an empirical, self-consistent, orthogonal tight-binding (SC-TB) mo…
High-pressure resistivity experiments were performed on the recently discovered superconductor, MgB2. Tc decreases quasi-linearly with applied pressure to 1.4 GPa at a rate of -2.0(1) K/GPa, which is somewhat larger than that derived from recently-reported ac susceptibility measurements. The reduction of Tc is consist…
In this paper, we'll answer several abstract, formal questions about the nature of crack growth and nucleation. Bringing a field theory point of view to fracture illuminates things in what I hope will be an entertaining way. Formally, what is the crack nucleation rate? Fracture is an instability of elastic theory unde…
The reactivities of metallic nanosystems in catalytic processes are considered. The activities of nanoparticles in catalysis are due to their unique microstructures, electronic properties and high specific surfaces of the active centres. The problems of increasing the selectivities of catalytic processes are discussed…
A series of nanocomposite materials that consisted of emeraldine base of polyaniline and layered montmorillonite (MMT) clay were prepared by effectively dispersing the inorganic nanolayers of MMT clay in organic polyaniline matrix via in-situ polymerization. Organic aniline monomers were first intercalated into the in…
2-(N-Phthalimido)ethanol (NPE) was prepared by reacting phthalic anhydride with ethanolamine in dimethy formamide medium. The NPE thus obtained was reacted with methacryloyl chloride in the presence of triethylamine to form the monomer, 2-(N-Phthalimido)ethyl methacrylate (NPEMA). Free radical polymerization technique…
TROSY-based HN(CO)CA 2D and 3D pulse schemes are presented for measurement of (13)C(alpha)-(13)C(beta) dipolar couplings in high molecular weight (15)N,(13)C,(2)H-labeled proteins. In one approach, (13)C(alpha)-(13)C(beta) dipolar couplings are obtained directly from the time modulation of cross-peak intensities in a…
ADVERTISEMENT RETURN TO ISSUEPREVCommunicationNEXTEffect of an Internal Anthranilamide Turn Unit on the Structure and Conformational Stability of Helically Biased Intramolecularly Hydrogen-Bonded DendronsBaohua Huang and Jon R. ParquetteView Author Information Department of Chemistry The Ohio State University Columbus…
A new equation describing the behavior of the structural relaxation time, tau(T,P), as a function of both pressure and temperature, is discussed. This equation has been derived from the Adam-Gibbs theory by writing the configurational entropy, S(c), in terms of the excess thermal heat capacity and of the molar thermal…
We visualize undulations in layered systems using a cholesteric stripe phase with a macroscopic supramicron periodicity. The wave vector of stripe pattern is in the cell's plane. The undulation is induced by an in-plane magnetic field normal to the stripes. The observed displacement of layers is much larger than the v…
A method is suggested for the coating of micron-sized particles by polymeric films based on surface-controlled precipitation. Polymer particles were coated by dextran and DNA in a water/ethanol mixture containing multivalent cations. A theoretical model for depositing polymers on colloidal particles is presented using…
We investigate two-dimensional (2D) melting in the presence of a one-dimensional (1D) periodic potential as, for example, realized in recent experiments on 2D colloids subjected to two interfering laser beams. The topology of the phase diagram is found to depend primarily on two factors: the relative orientation of th…
Five generations of poly(propylene imine) dendrimers have been modified by palmityl and adamantyl endgroups via a thiourea linkage. The synthesis of the thiourea dendrimers DAB-dendr-(NHCSNHAd)(n) and DAB-dendr-(NHCSNHC(16)H(33))(n) (n = 4, 8, 16, 32, 64) proceeds smoothly via the amino-terminated DAB dendrimer and th…
The transport and relaxation properties of a molecular supercooled liquid on an isobar are studied by molecular dynamics. The molecule is a rigid heteronuclear biatomic system. The diffusivity is fitted over four orders of magnitude by the power law $D\ensuremath{\propto}(T\ensuremath{-}{T}_{c}{)}^{{\ensuremath{\gamma…
The rotational dynamics of a supercooled model liquid of rigid A-B dumbbells interacting via a Lennard-Jones potential is investigated along one single isobar. The time-temperature superposition principle, one key prediction of mode-coupling theory (MCT), was studied for the orientational correlation functions C(l). I…
Titanium-containing mesoporous molecular sieve Ti−MCM-41 has been synthesized using colloidal silica as the silicon source and TiCl 3 solution as the titanium source and was characterized by X-ray diffraction, N 2 adsorption, UV−vis, and UV−Raman spectroscopies. The formation of anatase TiO 2 can be avoided during the…
Mesoporous silica materials (MCM-41) were characterized by 13 C and 29 Si magic angle spinning (MAS) NMR. 13 C chemical shifts reveal a high content of gauche conformations in the chain of cationic surfactant molecules within the nanopores. 13 C T 1 's and proton to carbon cross-polarization times ( T CH ) demonstrate…
A statistical mechanical treatment is given of the confinement of a wormlike polymer in an entangled solution to a tube, yielding quantitative predictions for the average tube diameter D(e) and macroscopic plateau modulus G, in the tightly entangled regime in which D(e) is much less than the persistence length L(p). T…