Materials Literature
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Multimode photoswitching between liquid-crystalline phases (nematic and isotropic) by photochromic organic molecules is reported here. The authors use optically active diarylethylenes to induce chirality in nematic liquid-crystalline (LC) phases and to obtain effective photomodulation of LC phases as well as gradual c…
Compressive plastic deformation of particle-reinforced metal–matrix composites is investigated through numerical modeling at high rates of strain. The numerical modeling is performed using axisymmetric unit cell models, with the particles treated as elastic ellipsoids or cylinders embedded within a viscoplastic matrix…
The dynamics of the ferrielectric-paraelectric transition in lamellar ${\mathrm{CuInP}}_{2}{\mathrm{S}}_{6}$ is studied using Raman scattering. Band assignments for this system are established by comparison with published vibrational spectroscopy information on related chalcogenophosphates as well as with new data on…
We predicted and measured the evolution of smooth muscle cell (SMC) orientation in media-equivalents (MEs) for four fabrication conditions (F-, M-, F+, M+) under Free or Mandrel compaction (F/M) with and without magnetic prealignment of the collagen fibrils in the circumferential direction (+/-). Mandrel compaction re…
We study the effects of finite temperature on the dynamics of non-planar vortices in the classical, two-dimensional anisotropic Heisenberg model with XY- or easy-plane symmetry. To this end, we analyze a generalized Landau-Lifshitz equation including additive white noise and Gilbert damping. Using a collective variabl…
Using kinetic Monte-Carlo simulations of a Solid-on-Solid model we investigate the influence of step edge diffusion (SED) and evaporation on Molecular Beam Epitaxy (MBE). Based on these investigations we propose two strategies to optimize MBE-growth. The strategies are applicable in different growth regimes: during la…
Growth of enteric bacteria on acetate as the sole source of carbon and energy requires operation of a particular anaplerotic pathway known as the glyoxylate bypass. In this pathway, two specific enzymes, isocitrate lyase and malate synthase, are activated to divert isocitrate from the tricarboxylic acid cycle and prev…
A new nonlinear optical (NLO) borate crystal K 2 Al 2 B 2 O 7 (Potassium Aluminum Borate, KAB) has been discovered. The structure has been established by 4-axis X-ray diffraction methods. The material crystallizes in the trigonal space group P321 with a = 8.5657(9) Å, C = 8.463(2) Å and Z = 3. KAB possesses a space ar…
The optical properties of alpha‐Al 2 O 3 have been determined by two independent methods, vacuum ultraviolet (VUV) spectroscopy and electron energy‐loss spectroscopy (EELS) over the energy range from 6 to 142 eV. For each experimental method two sets of high‐quality data have been measured and analyzed from alpha‐Al 2…
CdS/dendrimer nanocomposites that emit blue light are formed by the arrested precipitation of nanometer-scale CdS quantum dots in the presence of Starburst (poly(aminoamine)) dendrimers as the stabilizing host. The authors report a strong photoluminescence with emission maxima at about 450 nm. The optoelectronic prope…
A novel model system of hard colloidal platelets was observed to phase-separate into an isotropic and a liquid crystalline phase. Polarization microscopy revealed that the liquid crystalline phase was of nematic origin. With such orientational ordering in suspensions of platelike particles already being predicted in t…
A series of dendrimer porphyrins ((L 5 ) n P, n = 1−4), which bear different numbers ( n ) of five-layered dendron subunits (L 5 ) at the meso -positions of a porphyrin, were synthesized. Upon excitation of the dendron subunits in CH 2 Cl 2 at 20 °C, (L 5 ) n P showed an intramolecular singlet energy transfer from the…
A high-efficiency guided-mode resonance reflection filter is reported. The device consists of a surface-relief photoresist grating and an underlying HfO (2) waveguide layer deposited on a fused-silica substrate. The spectral response measured with a dye-laser beam at normal incidence exhibited a peak reflectance of 98…
A comparative analysis of quantitative infrared absorption spectra and mass selected thermal effusion transients measured for a large number of hydrogenated amorphous carbon (a-C:H) films is presented in order to establish reliable IR absorption cross sections for the different hydrogen bonding configurations in the m…
The size and shape of macromolecules such as proteins and nucleic acids play an important role in their functions. Prior efforts to quantify these properties have been based on various discretization or tessellation procedures involving analytical or numerical computations. In this article, we present an analytically…
The radial breathing mode is a promising candidate for the analysis of conformational and electronic properties of carbon nanotubes. The paper presents calculations based on the local density approximation to determine the radial breathing mode (RBM) frequency of various zigzag and armchair tubes with radii between 3.…
The addition of polyethylene glycol (PEG) and to an acid copper electrolyte inhibits the deposition reaction for cathodic overpotentials of up to about 150 mV. Adding only promotes the deposition reaction, while adding PEG alone has a relatively small effect on electrode kinetics. Frequency shifts of an electrochemica…
A diverse and entirely new class of monomer and polymer technology based on polyhedral oligomeric silsesquioxane (POSS) reagents has been developed. POSS reagents are unique in that they are physically large (approx. 15 Å diameter and 1000 amu) and are composed of a robust silicon–oxygen framework that can be easily f…
X-ray Diffraction: A Practical Approach, C. Suryanarayana and M. Grant Norton, 1998. Plenum Press, New York and London. xiii + 273 pages. (hardback, $49.50, U.S. and Canada; $59.40, elsewhere).It is the aim of this text to teach undergraduates majoring in materials science the use of powder X-ray diffraction for mater…
The 1985 discovery of the third form of ordered carbon, commonly known as the fullerenes, spurred the subsequent discovery of a number of related novel forms of carbon. The most famous among these carbons are the nanotubes, sometimes referred to as buckytubes as well. In this review, I discuss the structure, propertie…