Materials Literature
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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…
We study the adsorption of polyelectrolytes onto oppositely charged surfaces as the surface charge density is varied while keeping the polyelectrolyte charge density fixed. As observed previously from multilayer adsorption studies, 1,2 nonmonotonic adsorption behavior is obtained in the intermediate surface charge den…
We reconsider the interpretation of x-ray resonant scattering experiments performed on the so-called charge-ordered manganites with Mn 3+ /Mn 4+ = 1. The comparison between these experiments and our x-ray absorption data shows that no real Mn 3+ /Mn 4+ charge ordering occurs in these compounds. However, these experime…
We report a systematic study of manganese perovskites, RE 1- x D x MnO 3 (RE = rare earth; D = Ca, Sr), by means of x-ray absorption near edge structure (XANES) spectroscopy at the Mn K edge. High resolution has been achieved by recording the intensity of the Mn Kβ fluorescence spectrum. All the samples show a unique…
The electron microscopy study of the manganites Bi 1 - x Sr x MnO 3, especially for x = 1 / 2 and x = 2 / 3, has allowed a new type of modulated structure, correlated to charge ordering (CO) phenomena, to be evidenced. The Bi 1 - x Sr x MnO 3 manganites are characterized by a modulated structure, the modulation vector…
The addition of dodecanethiol to a polydisperse platinum colloidal aqueous solution capped with acrylic acid leads to self-assembled monolayers which not only contain various sizes, but also various shapes of nanoparticles. Assembled monolayers arranged in hcp arrays are achieved for mixed shape samples. In the case o…
Several single-molecule magnets with the composition [Mn12O12(O2CR)16(H2O)x] (x = 3 or 4) exhibit two out-of-phase ac magnetic susceptibility signals, one in the 4-7 K region and the other in the 2-3 K region. New Mn12 complexes were prepared and structurally characterized, and the origin of the two magnetization rela…
A drift-diffusion model for spin-charge transport in spin-polarized {\it p-n} junctions is developed and solved numerically for a realistic set of material parameters based on GaAs. It is demonstrated that spin polarization can be injected through the depletion layer by both minority and majority carriers, making all-…