Materials Literature
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Incorporating nanocrystals into future electronic or optoelectronic devices will require a means of controlling charge-injection processes and an understanding of how the injected charges affect the properties of nanocrystals. We show that the optical properties of colloidal semiconductor nanocrystal quantum dots can…
X-ray diffuse scattering for single crystals of KTa 1- x Nb x O 3 ( x = 0, 0.007 and 0.011) has been measured. For the sample of x = 0.011, peculiar x-ray diffuse scattering is observed above the phonon-frozen-in temperature (30 K). By an analysis of the diffuse scattering intensities, the average radius of the ferroe…
Based on the experimental work by Boscaino et al on the EPR transient nutations (TNs) and free induction decay (FID) in solids, we propose the modified Bloch equations (MBEs). In addition to the Tomita expression for power-dependent parameter T 2 u , we give an original phenomenological expression for power-dependent…
Simultaneous measurements of the magnetoresistance, magnetization, Hall effect, thermoelectric power and specific heat of a modified FeRh compound where 3.5 at.% Ni is doped at the Fe sites are investigated in order to elucidate the origin of the giant-magnetoresistance phenomena through the metamagnetic transition fr…
We use the soft fundamental measure theory (SFMT) to investigate a system of classical particles interacting with the pair potential of star polymers in solution. To that end we calculate liquid and solid structural properties, as well as freezing, solid-to-solid, and remelting phase transitions. Even subtle physical…
A series of new receptor molecules derived from 2,4,6,8-tetraazabicyclo[3.3.1]nonane-3,7-dione (propanediurea) is described. These molecules possess a cavity which is defined by two nearly parallel aromatic side walls positioned on top of a bis-urea framework. The resulting "U-shaped" clip molecules are ideal hosts fo…
Recently we reported that mesoporous niobium oxide can be chemically reduced by Na-naphthalene while fully retaining its mesostructure. This was the first report of a molecular sieve acting as a stoichiometric electron acceptor. Herein we expand on the initial work by presenting a detailed study on Li-, Na-, K-, Rb-,…
Escherichia coli glyoxalase I (GlxI) is a metalloisomerase that is maximally activated by Ni(2+), unlike other known GlxI enzymes which are active with Zn(2+). The metal is coordinated by two aqua ligands, two histidines (5 and 74), and two glutamates (56 and 122). The mechanism of E. coli Ni-GlxI was investigated by…
The Raman-active radial breathing modes (RBM) and tangential modes (TM) of single wall carbon nanotubes (SWNT) are studied at fixed laser excitation energy 2.41 eV (514.5 nm). We focus on the striking diameter dependence of the relative intensity of the TM and RBM between 0.9 and 2.1 nm, which displays a series of pla…
We present a general theoretical framework, based on the Preisach model of hysteresis, for describing irreversible phenomena in magnetically ordered materials, which includes the effects of the critical ordering temperature T C . The model is based on the premise that the free energy landscape can be decomposed into a…
Non-resonant Raman spectroscopy studies of a set of CdS films annealed at different temperatures were performed and showed a direct correlation between the width of the Raman peak produced by CdS-like optical phonons and the crystalline quality of the semiconductor phase probed by x-ray diffraction (XRD) and transmiss…
The magnetic properties of the polycrystalline manganites ${\mathrm{Sm}}_{1\ensuremath{-}x}{\mathrm{Ca}}_{x}{\mathrm{MnO}}_{3}$ have been studied for $(1>~x>~2/3)$ under high magnetic fields up to 50 T. The phase diagrams in the H-T plane have been determined. The more representative systems have also been studi…
We use a self-consistent field approximation to model the configurations of end-charged homopolymer and block copolymer brushes in response to an external electric field due to charges on the grafting surface. By varying the charge density on the grafting surface, we can cause the chains either to extend outward, grea…
The structural and magnetic properties of the Gd 2 Fe 17 D x compounds ( x = 0, 3, and 5) have been investigated by means of x-ray powder diffraction, high energy inelastic neutron scattering and magnetic measurements. The Gd 2 Fe 17 D x compounds crystallize in the R -3 m space group with the Th 2 Zn 17 -like structu…
Linear and nonlinear optical susceptibilities of the ferroelectromagnet ${\mathrm{YMnO}}_{3}$ below its N\'eel temperature ${(T}_{N})$ have been studied by using the first-principles full-potential linearized augmented plane-wave (FPLAPW) method within the local density approximation (LDA) plus the multi-orbital mean…
In previous works, we showed that the spinodal decomposition of low-viscosity liquid mixtures is driven by the convection induced by chemical potential gradients. In this article, we study the impact of this driving force on the phase separation of low-viscosity liquid mixtures in which a strong initial concentration…
The diffusion of planar aggregates of passivated CdSe nanocrystals on a graphite surface is investigated using AFM. These monolayer disks contain 80−100 identical 4 nm nanocrystals, with a total molecular weight of 4 × 10 7 amu, and yet diffuse rapidly on a graphite surface at 50−100 °C without dissociation. The distr…
The crystallization of shear oriented oxyethylene/oxybutylene (E/B) diblock copolymers has been studied by simultaneous small and wide angle x-ray scattering. Crystallization of ordered melts can be accompanied by a change in length scale and retention of the melt orientation. Lamellar melts crystallize with an increa…
We applied ellipsometry to study the distribution of azobenzene fragments in the films of two types of comblike polymers with azobenzene moieties in the side chains before and after ultraviolet (UV) light irradiation. The polymer with an alkyl chain at the end of the azobenzene fragment forms structures with preferred…
The vibrational density of states in the triphenyl phosphite, measured by inelastic neutron scattering, were obtained during isothermal aging at ${T}_{a}=210,$ 213, and 216 K. The low-frequency ${\ensuremath{\omega}}^{n}$ behavior of the vibrational density of states was observed to be time dependent. This is suggesti…