Materials Literature
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Two new cardenolides, 3beta-hydroxy-5alpha-carda-14(15), 20(22)-dienolide (beta-anhydroepidigitoxigenin) (1) and 3beta-O-(D-digitalosyl)-21-hydroxy-5beta-carda-8,14,16 , 20(22)-tetraenolide (neriumogenin-A-3beta-D-digitaloside) (2), and two known compounds, proceragenin and neridienone A (3), have been isolated from t…
The low-temperature oxidation during deposition by evaporation of molybdenum thin films has been investigated. Analysis by x-ray photoelectron spectroscopy and x-ray diffraction reveals that small differences in the substrate temperature during deposition may give rise to important changes in the final composition and…
The Isothermal Transient Ionic Current (ITIC) technique was applied to β-Ta2O5 samples made by chemical vapor deposition. The mobility, conductivity, and number of protons in the material could be extracted from the measurements. Li ions were intercalated electrochemically into the β-Ta2O5 and it was found that the IT…
A series of novel poly(arylene ether ketone)s were synthesized from the reaction of hydroquinone and 4-(4-hydroxyphenyl)-2,3-phthalazin-1-one with 4,4′-difluorobenzophenone in N-cyclohexylpyrrolidinone containing anhydrous potassium carbonate. The polymers exhibited high glass transition temperatures together with exc…
A heteroquantum dot (HQD) tunneling model for the conduction mechanism of hydrogenated nanocrystalline silicon films is proposed. The main features of the HQD model follow. (i) The micrograins and their amorphous counterparts have very different band gaps and band structures; as a result, they form a heterojunctionlik…
We investigate the possibility that freely rotating cylinders with an aspect ratio L/D=0.9 exhibit a cubatic phase similar to the one found for a system of cut spheres. We present theoretical arguments why a cubatic phase might occur in this particular system. Monte Carlo simulations do not confirm the existence of a…
Taylor cylinder impact testing is used to validate anisotropic elastoplastic constitutive modelling by comparing polycrystal computed yield–surface shapes (topography) with measured shapes from post–test Taylor specimens and quasi–static compression specimens. Measured yield–surface shapes are extracted from the exper…
The effects of Nd2O3 doping on the thermal and mechanical properties of vacuum melted, low silica, calcium aluminosilicate glasses are presented. For the doped glasses, the vitrification limit was found to correspond to a maximum load of 5 wt % Nd2O3. The influence of the rare earth doping on the thermal diffusivity,…
Dielectric relaxation measurements were performed on propylene glycol (PG) and oligomers having different number of repeat units (N=2, 3, and 69). The primary α-relaxation had the Kohlrausch–Williams–Watts (KWW) form, with a stretch exponent (1−n) which decreased with increasing N. The temperature dependence of the α-…
X-ray diffraction measurements have been performed on Nd 0.5 Sr 0.5 MnO 3 single crystals at various temperatures and magnetic fields. The temperature dependences of the lattice parameters show abrupt changes in the slopes at the ferromagnetic transition temperature of 250 K. Discontinuous changes in the lattice param…
The effect of low levels of poly(o-methoxyaniline) (POMA) on the crystallization, morphology, and electrical characteristics of blends with poly(vinylidene fluoride) (PVDF) were studied by infrared spectroscopy, AC electrical measurements, and optical microscopy. Undoped POMA has a strong effect in increasing the α-ph…
We extend the symmetrized density-matrix renormalization-group method to compute the dynamic nonlinear optical coefficients for long chains. By computing correction vectors in the appropriate symmetry subspace, we obtain the dynamic polarizabilities, ${\ensuremath{\alpha}}_{\mathrm{ij}}(\ensuremath{\omega})$, and thir…
The title compound, tetracalcium dialuminum dodecahydroxide dinitrate tetrahydrate, of composition 3CaO.Al 2 O 3 .Ca(NO 3 ) 2 .10H 2 O, is a layered compound constituted by positively charged [Ca 4 Al 2 (OH) 12 ] 2+ main layers and negatively charged [2NO 3 .4H 2 O] 2- interlayers. It crystallizes in the trigonal P3c1…
We calculate the optical constants of porous silicon (por-Si) from the electronic band structure obtained by means of an ${\mathrm{sp}}^{3}{s}^{*}$ tight-binding Hamiltonian and a supercell model, in which the pores are columns dug in crystalline Si. The position of the absorption edge of the material is defined by tw…
The conduction-band structure of single crystals ${\mathrm{Bi}}_{2\ensuremath{-}x}{\mathrm{Sb}}_{x}{\mathrm{Se}}_{3}$ $(0<~x<~0.52)$ was investigated in high magnetic fields by the Shubnikov--de Haas (SdH) effect (up to 40 T) and cyclotron resonance (up to 150 T). Signals from two conduction bands were detected…
The melt spinning of nylon 6 has been studied with on-line wide-angle synchrotron X-ray scattering techniques. The apparatus consisted of a single screw extruder and a metering pump mounted on a horizontal platform that could be translated in the vertical direction allowing a range of distances to be sampled with the…
The effects of different types of boundaries on graphite fragments are considered as they influence the π-electrons. From a simple resonance theoretic argument there are proposed simple structural conditions governing the occurrence of “unpaired” π-electron density near the edges. Predictions based on these rules are…
The finite–element (FE) method is commonly used to solve boundary value problems in continua. Constitutive equations based on crystal plasticity have been implemented in FE simulations, and these slip–based calculations have the potential to model a variety of interesting phenomena. However, the substructure of the de…
The magneto-optic (MO) Kerr and Faraday spectra for manganese pnictides are calculated using the all electron, relativistic, full-potential linear muffin-tin orbital method. The amplitude of our calculated spectra are found to be in good agreement with corresponding experimental spectra. Although the MO property is a…
We have studied the electronic structure of a class of half-Heusler compounds $M\mathrm{NiPn},$ where M is Y, La, Lu, Yb, and Pn is a pnicogen As, Sb, Bi. All these systems excepting Yb are narrow-gap semiconductors and are potential candidates for high-performance thermoelectric materials. The Yb system shows heavy f…