Materials Literature
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Structures of carbon nanotube/ligand complexes were studied by flow linear dichroism (the differential absorption of light polarized parallel and perpendicular to the flow orientation direction) with the aim of establishing linear dichroism as a technique to study such systems. Anthracene, naphthalene, and DNA were ch…
Two fluoride-encapsulated octasilsesquioxane cage compounds have been prepared using the TBAF route as important molecular models for studying ion entrapment in siliceous zeolites. Analyses by X-ray crystal structure and solution 19 F/ 29 Si NMR spectroscopy reveal very similar environments for the encapsulated fluori…
Age concern: Alkyl amine templates act as bifunctional surfactants which can template mesostructures with microporous walls. Ordered two-dimensional hexagonal mesoporous iron oxide with P6mm symmetry and three-dimensional cubic mesoporous iron oxide with Fm3m symmetry (see TEM image) have been prepared by using decyla…
We present in this paper a solid-state sample of microwave metamaterial produced by a standard hot-press technique for the manufacture of printed circuit boards. We performed three experiments to demonstrate that this sample is a left-handed material with negative refractive index. The three experiments are power tran…
PURPOSE: To choose an efficacious renal functional MRI contrast agent to image early renal tubular damage. We synthesized and compared smaller polyamine dendrimer-based MRI contrast agents (<60 kD) that, unlike Gd-[DTPA], transiently accumulate in renal tubules and can be used to visualize renal structural and functio…
Spider dragline silk is a unique biomaterial and represents nature's strongest known fibre. As it is almost as strong as many commercial synthetic fibres, it is suitable for use in many industrial and medical applications. The prerequisite for such a widespread use is the cost-effective production in sufficient quanti…
Abstract We have carried out a first‐principles total‐energy calculation of the structural and the elastic properties for the series of boron compounds BP, BAs, and BSb. We have applied the augmented plane‐wave plus local‐orbitals method with both the local‐density approximation (LDA) and the generalized gradient appr…
A highly active, monomeric chorismate mutase, obtained by topological redesign of a dimeric helical bundle enzyme from Methanococcus jannaschii, was investigated by NMR and various other biochemical techniques, including H/D exchange. Although structural disorder is generally considered to be incompatible with efficie…
The first three-dimensional structure of phenylalanine ammonia lyase (PAL) has been determined at 2.1 A resolution for PAL from Rhodosporidium toruloides. The enzyme is structurally similar to the mechanistically related histidine ammonia lyase (HAL), with PAL having an additional approximately 160 residues extending…
Diamond-like carbon (DLC) films were deposited on a Si substrate by electrolysis in a methanol solution at ambient pressure and low temperature. The morphology and microstructure of the resulting DLC films were analysed using atomic force microscopy, Raman spectroscopy, Fourier transformation infrared spectrometry, x-…
We have investigated the effect of doping by Te on the anomalous Hall effect in Ga1-xMnxAs (x = 0.085). For this relatively high value of x the temperature dependence of resistivity shows an insulating behavior. It is well known that in Ga1-xMnxAs the Mn ions naturally act as acceptors. Additional doping by Te donors…
We present a comprehensive examination of optical pumping of spins in individual GaAs quantum dots as we change the charge from positive to neutral to negative using a Schottky diode. We observe that photoluminescence polarization memory has the same sign as the net charge of the dot. Optical pumping of ground state e…
We investigate theoretically the influence of the spin-orbit interaction of Rashba type on the magnetoresistance of a semiconducting ferromagnetic nanostructure with a laterally constrained domain wall. The domain wall is assumed sharp (on the scale of the Fermi wave length of the charge carriers). It is shown that th…
Molecular dynamics simulations show that gold clusters with about 600--3000 atoms crystallize into a Mackay icosahedron upon cooling from the liquid. A detailed surface analysis shows that the facets on the surface of the Mackay icosahedral gold clusters soften but do not premelt below the bulk melting temperature. Th…
Recent theories predict dissipationless spin current induced by an electric field in doped semiconductors. Nevertheless, the charge current is still dissipative in these systems. In this work, we theoretically predict the dissipationless spin Hall effect, without any accompanying charge current, in some classes of ban…
To understand the effect of molecular environment on the electronic and magnetic properties of the single-molecule magnet ${\mathrm{Mn}}_{12}$, we explore two possible means for adding extra electrons to molecule. We explore both substitution of Mn ions by Fe ions and the inclusion of neighboring electronic donors. Fo…
The magnetic properties of dilute magnetic semiconductors (DMS) are calculated from first-principles by mapping the ab initio results on a classical Heisenberg model. It is found that the range of the exchange interaction in (Ga, Mn)N is very short ranged due to the exponential decay of the impurity wave function in t…
We study AB n miktoarm star block copolymers in the strong segregation limit, focusing on the role that the AB interface plays in determining the phase behavior. We develop an extension of the kinked-path approach which allows us to explore the energetic dependence on interfacial shape. We consider a one-parameter fam…
Stainless steels undergo a sharp rise in pitting corrosion rate as the potential, solution concentration, or temperature is changed only slightly. We report experiments using real-time microscopic in situ visualizations that resolve the nucleation and evolution of individual pits during the transition. They suggest th…
We report on the experimental observation of magnetic hysteresis up to room temperature in thiol-capped Au nanoparticles with 1.4 nm size. The coercive field ranges from 860 Oe at 5 K to 250 Oe at 300 K. It is estimated that the Au atoms exhibit a magnetic moment of mu=0.036mu(B). However, Au nanoparticles with simila…