Materials Literature
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To understand sparse systems we must account for both strong local atom bonds and weak nonlocal van der Waals forces between atoms separated by empty space. A fully nonlocal functional form [H. Rydberg, B.I. Lundqvist, D.C. Langreth, and M. Dion, Phys. Rev. B 62, 6997 (2000)] of density-functional theory (DFT) is appl…
While microscopic laws of physics are invariant under the reversal of the arrow of time, the transport of energy and information in most devices is an irreversible process. It is this irreversibility that leads to intrinsic dissipations in electronic devices and limits the possibility of quantum computation. We theore…
We present a new complementary strategy to quasicrystalline structure determination: The local atomic structure of simple icosahedral (si) Ho11Mg15Zn74 [a(6D)=5.144(3)A] in a sphere of up to r=17A was refined using the atomic pair distribution function (PDF) from in-house X-ray powder diffraction data (MoKa1, Qmax=13.…
Motivated from the flat-band ferromagnetism conceived theoretically for a single chain of five membered rings (polyaminotriazole) by Arita {\it et al.}, [Phys. Rev. Lett. {\bf 88}, 127202 (2002)], we have studied whether the magnetism can indeed occur as a bulk, i.e., in a three-dimensional crystal of the polymer, by…
A heterotrinuclear lanthanide complex has been prepared which contains two terbium ions in DO3A-derived binding sites and a single ytterbium ion in a DTPA-like site. The luminescence properties of the system have been investigated, showing that the terbium remains in a seven-coordinate binding site throughout the synt…
An individual carbon nanocoil was clamped between two AFM cantilevers and loaded in tension to a maximum relative elongation of ∼42%. The deformation of the nanocoil agrees well with an analytical model of the spring constant that accounts for the geometric nonlinearity. The nanocoil behaves like an elastic spring wit…
Poly(acrylonitrile) solutions in dimethylformamide were electrospun to be webs consisting of 300 nm ultrafine fibers. The webs were oxidatively stabilized and activated by steam resulting in activated carbon nanofibers (ACNFs). The specific surface area of the ACNF activated at 700 °C was the highest but mesopore volu…
Spectrofluorimetric data for identified single-walled carbon nanotubes in aqueous SDS suspension have been accurately fit to empirical expressions. These are used to obtain the first model-independent prediction of first and second van Hove optical transitions as a function of structure for a wide range of semiconduct…
UV irradiation of ultrathin ${\mathrm{SiO}}_{2}$ on Si can lead to injection of both holes and electrons into the oxide. 4.9-eV photons lead to electron injection while 6.7-eV photons open up the hole injection channel. The holes and electrons can trap, generating electric fields of opposite signs. Second harmonic gen…
We have measured the infrared reflectivity spectra of ${\mathrm{La}}_{1\ensuremath{-}y}[\mathrm{Sr}(\mathrm{Ba}){]}_{y}{\mathrm{Mn}}_{1\ensuremath{-}x}[\mathrm{Cu}(\mathrm{Zn},\mathrm{Sc}){]}_{x}{\mathrm{O}}_{3}$ $(0<y<~0.3,0<~x<~0.10)$ manganites, in a wide frequency $(100--4000{\mathrm{cm}}^{\ensuremath{…
To learn the structural basis for the unusually tight binding of 8-oxo-nucleotides to the MutT pyrophosphohydrolase of Escherichia coli (129 residues), the solution structure of the MutT-Mg(2+)-8-oxo-dGMP product complex (K(D) = 52 nM) was determined by standard 3-D heteronuclear NMR methods. Using 1746 NOEs (13.5 NOE…
Let's twist again: While the photoisomerization of stilbene analogues in fluid solution occurs by a one-bond-flip mechanism and involves only configurational changes, in a solid solution (glass) a Hula-twist mechanism operates and results in conformational as well as configurational changes (see scheme).
We present the results of an x-ray magnetic circular dichroism (XMCD) investigation of the molecular superparamagnet Mn12-ac. Thanks to an approach based on chemical synthesis of model compounds, the contributions of Mn(III) and Mn(IV) ions to the absorption spectrum and the dichroic signal of Mn12-ac have been separa…
Hybrid core–corona nanoassemblies (shown schematically in the picture, middle) can be used as supramolecular precursors for metal hydroxide colloids (right) with long-term stability. Anionic–neutral hydrophilic diblock copolymers allow metal hydrolysis and condensation reactions to occur in suspension. Particle size a…
Abstract Novel diols containing imide groups were prepared via condensation of aromatic dianhydrides with 5‐amino‐1‐naphthol. The diimide–dinaphthols prepared were characterized by conventional methods and used to synthesize new poly(urethane–imide)s (PUIs). All the polymers were characterized and their physical prope…
Hysteresis phenomena are investigated around the temperature-induced neutral-ionic (N-I) phase transition in the prototype compound tetrathiafulvalene-p chloranil (TFF-CA). A multistep transition is evidenced by neutron scattering, with plateau evolution of Bragg peaks characteristic of symmetry breaking, as well as b…
Abstract A synthetic pathway to functionalized six‐membered dilactones structurally analogous to lactide is described. Through the use of orthogonal protecting groups, the synthesis of functionalized dilactones was performed in a straightforward way by cyanuric chloride‐mediated cyclization of the corresponding linear…
The current picture: Electrochromic and uniform films of different conducting polymers on mirror-polished platinum electrodes were electrochemically reduced and compacted to show the formation and growth of colored nuclei under potentiostatic oxidation (see photographs of films). By interruption of the nucleus growth,…
The propagation and refraction of a cylindrical wave created by a line current through a slab of backward-wave medium, also called left-handed medium, is numerically studied with a finite-difference time-domain method. The slab is assumed to be uniaxially anisotropic. Several sets of constitutive parameters are consid…
It has recently been found that Pluronics (block copolymers of ethylene oxide, EO, and propylene oxide, PO) favor the permeability and accumulation of anthracycline antibiotics, for example doxorubicin (Dox), in tumor cells. In an effort to understand these results, the interaction of EO(2)/PO(32)/EO(2) (Pluronic L61)…