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。
Up to 14 porphyrin rings are present in the title compounds 1, which are readily available with high regioselectivity from linear nickel-zinc porphyrins. Upon irradiation with light a rapid energy transfer from the peripheral porphyrin rings to the diporphyrin core takes place.
Using molecular dynamics computer simulations we investigate how the relaxation dynamics of a simple supercooled liquid with Newtonian dynamics differs from the one with a stochastic dynamics. We find that, apart from the early $\ensuremath{\beta}$-relaxation regime, the two dynamics give rise to the same relaxation b…
We calculated the effects of structural distortions on the electronic structure of carbon nanotubes. The key modification of the electronic structure brought about by bending a nanotube involves an increased mixing of $σ$ and $π$-states. This mixing leads to an enhanced density-of-states in the valence band near the F…
In order to resolve the controversy about the low density region of the phase diagram of the 4He monolayer on graphite, we have undertaken a path integral Monte Carlo study of the system. We provide direct evidence that the low density monolayer possesses solid clusters and a low density vapor as opposed to the most r…
Spiral surface growth is well understood in the limit where the step motion is controlled by the local supersaturation of adatoms near the spiral ridge. In epitaxial thin-film growth, however, spirals can form in a step-flow regime where desorption of adatoms is negligible and the ridge dynamics is governed by the non…
We have fabricated a nematic liquid crystal cell associated with a homogeneously aligned to twisted transition of a liquid crystal director. In the absence of an electric field, the liquid crystal molecule is homogeneously aligned under the crossed polarizers, and thus the cell appears to be black. When a fringe field…
In recent years, well-defined and nearly perfect single crystal surfaces of oxide perovskites have become increasingly important. A single terminated surface is a prerequisite for reproducible thin film growth and fundamental growth studies. In this work, atomic and lateral force microscopy have been used to display d…
The drying mechanism of semicrystalline poly(vinyl alcohol) (PVA) was investigated. PVA samples of various molecular weights were crystallized by annealing at temperatures slightly above the glass transition temperature of PVA, and swollen in water for different time periods. The water volume fraction in the sample wa…
The effect of substrate temperature on the homoepitaxial growth process of a SrTiO3(001) surface has been investigated using our crystal growth molecular dynamics simulation code. SrO molecules were continuously deposited one by one on the SrTiO3(001) surface terminated by TiO2 atomic plane at 300 K. Two-dimensional a…
Three-amide oligomers of nylon 6 and nylon 6 6 have been investigated using electron microscopy (imaging and diffraction), X-ray diffraction, and computational modeling. A new crystal structure has been discovered for the three-amide oligomer of nylon 6. This material crystallizes from chloroform/dodecane solutions in…
Optical absorption spectra of nanoclusters of lead iodide, synthesized by the colloidal technique, have been investigated. It is shown that the absorption peaks are due to different orders of interband transitions of a nominally single size of particles rather than the first-order transitions of a number of discrete s…
In this article we will focus on the dielectric properties of laminates and blends of a partially conducting (the liquid crystalline copolyesteramide Vectra B950) and an insulating (polypropylene or mica) phase. Dielectric spectroscopy was used as a tool to obtain information about the influence of the dimensions of t…
Ion implantation induced dc electrical conductivity changes in polycrystalline WO3 thin films was examined. Helium, argon, and tungsten ions were implanted under the following conditions: helium at 90 keV, argon at 360 keV, and tungsten at 300 keV. The fluence range studied was from 1×1017 to 3×1017 cm−2 for helium an…
A method for crystallizing oriented samples of the γ-phase of isotactic polypropylene (iPP) under atmospheric pressure in the presence of nucleating fibers has been developed. The technique uses iPP grades of high molecular weight and high isotacticity and produces a mixture of α and γ-phase crystals within the matrix…
A Landau free energy is derived for the weak segregation regime (WSR) of melts belonging to a very general class of statistical multiblock copolymers, referred to as “multiple segment-type statistical multiblock copolymers.” Copolymer chains in this class consist of sequences of up to M⩾2 chemically different types of…
Poly(dimethylsiloxane) was studied by laser Raman spectroscopy and differential scanning calorimetry. The SiOSi skeletal mode at 489 cm−1 and the CSiC deformation bands at 188 cm−1 and 158 cm−1 were studied as functions of temperature from ambient to −130°C, and effects of temperature interpreted in accordance wit…
Barium dicobalt(II) bis(phosphate) is built up from BaO12 polyhedra [dav(Ba—O) = 2.995 (1) Å], CoO6 octahedra [dav(Co—O) = 2.098 (2) Å] and PO4 tetrahedra [dav(P—O) = 1.544 (2) Å]. The structure has a strongly layered nature, with Ba2+ cations interspersing infinite sheets of edge-sharing CoO6 groups, which are capped…
${}^{29}\mathrm{Si}$ nuclear magnetic resonance spectra were measured to characterize porous silicon structures. ${}^{29}\mathrm{Si}$ nuclei close to surface were selectively detected both in cross-polarization and non-cross-polarization spectra. The spectra were different from those for amorphous silicon and amorphou…
The thermal response of tussah (Antheraea pernyi) silk fibroin films treated with different water–methanol solutions at 20°C was studied by means of dynamic mechanical (DMA) and thermomechanical (TMA) analyses as a function of methanol concentration and treatment time. The DMA curves of α-helix films (treated with ≥80…
We report the results of an optical study of the Mott transition in ${\mathrm{V}}_{2}{\mathrm{O}}_{3}$ carried out by time- and frequency-domain spectroscopies. We have observed time-resolved spectra through the Mott transition with oscillations in reflectivity associated with the fully symmetric modes. As a consequen…