Materials Literature
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The X-ray magnetic circular dichroism (XMCD) has been measured at the Co K edge in Co-hcp and R-Co compounds (R=La, Tb, Dy). The structure of the experimental XMCD spectra in the near-edge region has been observed to be highly sensitive to the magnetic environment of the absorbing site. Calculations of the XMCD have b…
The scattering from crystals can be divided into two parts: Bragg scattering and diffuse scattering. The analysis of Bragg diffraction data gives only information about the average structure of the crystal. The interpretation of diffuse scattering is in general a more difficult task. A recent approach of analysing dif…
A materials selection methodology and its software implementation, developed to aid the designer in making environmentally conscious decisions early in the design process, is described.
A diffraction grating technology based upon volume-phase holograms shows promise of enhanced performance for many applications in astronomical spectroscopy over classical surface-relief grating technology. We present a discussion of the underlying physics of a volume-phase grating, give some theoretical performance ch…
Ab-initio calculations have been used to study the influence of the interface morphology and, notably, of the exchange reaction on the electronic properties of Al/GaN (100) interfaces. In particular, the effects of interface structure (i.e. interfacial bond lengths, semiconductor surface polarity, and reacted intralay…
In this letter, structural rigidity concepts are used to understand the origin of instabilities in granular aggregates. It is shown that: a) The contact network of a noncohesive granular aggregate becomes exactly isostatic in the limit of large stiffness-to-load ratio. b) Isostaticity is responsible for the anomalousl…
A new type of crystalline structure for nonlinear optics whereby octupolar symmetry features are displayed at both molecular and crystalline levels is exemplified by the prototype 2,4,6-triaryloxy-1,3,5-triazine (TPOT) crystal and analyzed in terms of both individual molecular responses and crystal packing features. P…
The two most prominent peaks in the far-ultraviolet (UV) circular dichroism (CD) spectra of proteins occur at 190 nm (associated with the ππ* transition) and 220 nm (associated with the nπ* transition). The mean residue ellipticity at 220 nm, [θ]220, is commonly used to estimate the helix content of a protein. We have…
According to the singularity-free interpretation of the thermodynamics of supercooled water, the isothermal compressibility, isobaric heat capacity, and the magnitude of the thermal expansion coefficient increase sharply upon supercooling, but remain finite. No phase transition or critical point occurs at low temperat…
Phase diagrams for reversibly associating one-end-functionalized chain molecules (with an emphasis on hydrogen bonding) are determined by computer simulations of a cubic lattice model employing canonical and grand canonical Monte Carlo methods. Due to the relatively short chain lengths used, the stability of the homog…
The crossover to Rouse-type behavior for the self-diffusion constant D, the viscosity η, and the equilibrium structural statistics of n-alkanes (6⩽n⩽66) is studied numerically. For small n the chains are non-Gaussian and the mean squared end-to-end distance 〈R2〉 is greater than 6〈RG2〉, where 〈RG2〉 is the mean squared…
Spin-dependent conductance across a manganate-barrier-manganate junction has recently been demonstrated. The junction is a La$_{0.67}$Sr$_{0.33}$MnO$_3$% -SrTiO$_3$-La$_{0.67}$ Sr$_{0.33}$MnO$_3$ trilayer device supporting current-perpendicular transport. Large magnetoresistance of up to a factor of five change was ob…
Electronic properties of disordered binary alloys are studied via the calculation of the average Density of States (DOS) in two and three dimensions. We propose a new approximate scheme that allows for the inclusion of local order effects in finite geometries and extrapolates the behavior of infinite systems following…
The ion and polymer content of polyelectrolyte multilayers constructed via layer-by-layer deposition have been directly probed using radioanalytical methods. Multilayers were fabricated using salt-containing or salt-free solutions. Charges on polyions quantitatively balance each other. As-deposited multilayers contain…
Although porous silicon has received the most attention over the last 5 years, other structures containing Si nanocrystallites have recently been shown to emit strong luminescence at room temperature. This presentation reviews the state-of-the-art in the preparation and properties of silicon quantum dot structures, an…
An attempt is made to assess the extent of influence of various parameters on the breakdown mechanism in short rod–plane gaps under positive impulses. Such parameters include front duration and peak value of the impulse voltage, gap length, profile of the rod and, in particular, absolute humidity. Depending on the abo…
The oxidation behaviour of the phase in Nd-Fe-B sintered magnets containing additional elements (Al, Co, V, Nb, Mo) was investigated by Mössbauer spectrometry. The microstructure of the different samples was first characterized. Added elements were detected in both intergranular and intragranular precipitates. The pre…
The phase transition in sol-gel-derived barium titanate thin films has been investigated. The room temperature dielectric constant ) and loss tangent of the films were found to be 400 and 0.01 respectively. The dielectric constant has a broad peak of lower magnitude at . The polarization-field relationship ( P - E ) h…
Circulating-current loss in stranded windings of transformers has always attracted the attention of transformer designers. Analytical formulae based on the axial leakage field have long been used by designers for the calculation of circulating-current loss. The authors discuss these analytical formulae and compares th…
A mixed glass former effect has been observed in the glassy system 0.3Li 2 S−0.7[(1− x )SiS 2 − x GeS 2 ], where 0 ≤ x ≤ 1. It corresponds to a large enhancement of ionic conductivity for compositions 0.50 ≤ x ≤ 0.64. The variations of the electrical characteristics are closely related to those of the glass transition…