Materials Literature
按标题、摘要、年份、主题和来源检索公开元数据。结果保留作者、摘要、分类与原始来源链接。
Magnetic properties of carbon nanotubes (CN's) are calculated in the effective-mass theory. The magnetic moment in a magnetic flux parallel to the tube axis oscillates as a function of the flux with period determined by the flux quantum and phase depending on whether CN is metallic or semiconducting. For a magnetic fi…
Electron and x-ray-diffraction studies of nanotubes have revealed that the distances between the graphitic sheets are larger by a few percent than those in bulk graphite. The mean value of the interlayer spacings is 0.344\ifmmode\pm\else\textpm\fi{}0.001 nm.
We have studied the microstructure and optical properties of free-standing porous Si thin films fabricated by electrochemical anodization. Raman-spectroscopy and transmission-electron-microscopy examinations show that Si crystallite spheres with diameters of several nanometers are dispersed in the amorphous phase. The…
We analytically study phonon transmission and localization in random superlattices by using a Green's-function approach. We derive expressions for the average transmission rate and localization length, or Lyapunov exponent, in terms of the superlattice-structure factor. This is done by considering the backscattering o…
The oxygen 1s x-ray-absorption spectra of ${\mathrm{SrTiO}}_{3}$ and ${\mathrm{TiO}}_{2}$, in both the rutile and anatase crystal structure, are analyzed using the oxygen p-projected density of states of ground-state band-structure calculations. Good agreement is found and it is concluded that multielectron effects, t…
An elastic-plastic finite element method numerical model has been formulated to study residual stresses developed at graded ceramic-metal interfaces during cooling. The results were compared with those obtained for sharp (nongraded) interfaces to assess the potential for achieving residual stress reductions. Analyses…
We have used femtosecond optical spectroscopy to study the dynamics of excitons strongly confined in microcrystallites of the narrow-band-gap semiconductor PbS. The transient absorption of the lowest exciton level exhibits terahertz-frequency vibronic quantum beats. Far-infrared measurements show that the vibrations a…
Raman spectroscopy is used to study residual stress in diamond grown on Ti--6Al--4V by chemical vapor deposition. A general model is developed to use Raman spectroscopy to measure biaxial stress in polycrystalline, diamond-structure films. The as-grown film has 7.1 GPa of residual compressive stress, consistent with t…
High-resolution ${\mathit{p}}_{\mathit{z}}$- and ${\mathit{p}}_{\mathit{x},}$y-projected fine structure for the 1s carbon core level in graphite are compared with symmetry-projected calculations. A very sharp transition occurs about 7.6 eV above the Fermi energy in the ${\mathit{p}}_{\mathit{x},}$y results, agreeing c…
Lithium borosilicate and lithium chloroborosilicate were prepared. These are considered basic systems to study the effect of chloride ions on structure and ionic conductivity. It was found that the replacement of Li 2 O by LiCl enhanced the conductivity. It was also found that the molar volume increases on increasing…
Abstract Sorption and diffusion of dichloromethane vapor were measured in amorphous syndiotactic polystyrene films, obtained with different cooling conditions and after controlled aging times at different temperatures. The diffusional behavior, at the temperature of 25°C, was characterized by three stages, depending o…
Uphill diffusion, the diffusion of a component up its own concentration gradient, has often been observed in experimental studies of diffusion in synthetic multicomponent systems and natural silicate melts. To apply experimental data to natural processes, it is necessary to quantify this effect. A modified effective b…
The solvent dependence of the second hyperpolarizability, gamma, of a variety of unsaturated organic compounds has been measured by third harmonic generation at 1907 nanometers. It is seen that the measured gamma is a function of solvent polarity. These solvent-dependent hyperpolarizabilities are associated with chang…
Abstract A new multisolution phasing method based on entropy maximization and likelihood ranking, proposed for the specific purpose of increasing the accuracy and sensitivity of probabilistic phase indications compared with conventional direct methods, has been implemented and applied to a wide variety of problems. Th…
A preclinical toxicology study of intravenously administered liposome encapsulated doxorubicin (TLC D-99), free doxorubicin and empty liposomes was carried out in mice and dogs by single and multiple (daily for 5 days) dose schedules. Single dose intravenous injection studies in mice showed the encapsulated form of do…
Germanosilicate glasses soaked in high pressure hydrogen at low temperature exhibit markedly increased photoinduced refractive index changes when exposed to 248 nm UV radiation. The mechanisms involved include both photolytically and thermally driven reactions between hydrogen and germania, forming OH and deep UV abso…
Abstract Nodal surfaces, defined by wave vectors in a reciprocal space, equipotential surfaces, defined by point charges in real space, and periodic minimal surfaces, ‘soap-film’ elements lying smoothly across the asymmetric domains in given crystallographic symmetry groups, are exact mathematical objects which may be…
The cardiotoxic potential of liposome encapsulated doxorubicin (TLC D-99) prepared by a remote-loading technique was compared with that of free doxorubicin (1.5mg/kg administered every 3 weeks for 8 cycles) in beagle dogs. Both agents were equally myelosuppressive, and all dogs completed both treatments. There were no…
Abstract High resolution time-of-flight neutron powder diffraction has been used to determine the detailed structure of C60 as a function of temperature. Rapid data collection coupled with high resolution has enabled subtle aspects of the 86 K orientational glass transition and precursor effects of the 260 K order-dis…
Abstract The effects of an impact modifier, mean stress level, and test frequency on the fatigue crack propagation rate in a miscible amorphous blend of polycarbonate and a copolyester were investigated. Experiments were performed on a servohydraulic testing machine, in load control, using a sinusoidal waveform. The a…