Materials Literature
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3,4-Bis(trimethylsilyl)-1H-pyrrole (5) was employed as a key precursor to generate a highly strained and reactive five-membered cyclic cumulene, namely 1-tert-butoxycarbonyl-3,4-didehydro-1H-pyrrole (4). The transient existence of 4 at room temperature was confirmed by trapping reactions with furan, acrylonitrile, and…
Atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS) were used to study the size and distribution of nanometer-sized metallic particles of four Cu/SiO 2 model catalyst systems. The systems were constructed by spin coating copper(II) acetate [Cu(CH 3 CO 2 ) 2 ·H 2 O, Cu(ac) 2 ] solutions of varying…
Foams have unique rheological properties that range from solid-like to fluid-like. We study two-dimensional non-coarsening foams of different disorder under shear in a Monte Carlo simulation, using a driven large-Q Potts model. We find that the dynamics of topological rearrangements depend sensitively on the structura…
The implementation of an ultrasonic method of evaluation of composite plates requires a good knowledge of the interaction of ultrasonic beam emitted by the transducers, with such a plate immersed in a fluid. The model of ultrasonic propagation in anisotropic multilayered materials developed here makes the study of thi…
We propose an alternative approach to self-diffusion in an atomic liquid. Our starting point is an oscillatory motion of a tagged particle in its first solvation shell (cage). Only after cage relaxation is taken into account is the tagged particle able to diffuse. This approach is suitable for describing liquids where…
Tunneling spectroscopy of ${\mathrm{Al}}_{73}{\mathrm{Ni}}_{17}{\mathrm{Co}}_{10}$ decagonal single quasicrystals has been measured at ultralow temperatures. In addition to the wide pseudogap observed in previous photoemission experiments, very rich fine structures in the density of states around the Fermi energy were…
A generalized random sequential adsorption (RSA) approach is developed by taking into account diffusion, particle/wall hydrodynamic interactions as well as external forces (e.g., gravity). In analogy to the previous concept of Pagonabarraga and Rubı́ [Physica A 188, 553 (1992)] the position dependent available surface…
Exposure of Rh(111) to atomic oxygen leads to the facile formation of a full-coverage and ordered (1×1)-O monolayer which is stable at room temperature. This result differs markedly from the half-coverage (2×1)-O overlayer which forms at saturation when using molecular oxygen. This demonstrates that kinetic rather tha…
We present a new Monte Carlo scheme for the efficient simulation of multi-polymer systems. The method permits chains to be inserted into the system using a biased growth technique. The growth proceeds via the use of a retractable feeler, which probes possible pathways ahead of the growing chain. By recoiling from trap…
A new model is presented for the mesoscale modelling of grain–boundary motion. Grain boundaries are treated as regions of disorder across which orientation parameters change. The framework uses a set of lattice parameters to track grain orientation, and this is done with fewer equations than the more standard approach…
The precursor state involved in the initial stages of ${\mathrm{O}}_{2}$ reaction with a $\mathrm{Si}(111)\ensuremath{-}(7\ifmmode\times\else\texttimes\fi{}7)$ surface has been a long standing problem. Using the ${\mathrm{Cs}}^{+}$ reactive scattering technique, we unambiguously show that the precursor is molecular Si…
The spontaneous ultraviolet luminescence reported [G. M. Irwin and K. H. Kim, Phys. Rev. Lett. 79, 990 (1997); D. S. Richardson et al., ibid. 80, 3206 (1998)] from ${}^{233}\mathrm{uranium}$ compounds and ascribed to an ultraviolet gamma-ray emission from the metastable ${}^{229}\mathrm{thorium}$ daughter is actually…
The conditions for formation of subsurface oxygen on the Ru(0001) surface have been studied using thermal desorption spectroscopy, low energy electron diffraction (LEED) and specular helium scattering. The incorporation of oxygen has been performed via dissociative chemisorption of three molecular carriers of atomic o…
Spreading of perfluoropolyalkylether thin films on amorphous carbon surfaces has been studied by scanning microellipsometry. Two types of perfluoropolyalkylethers with the same main-chain structure and various molecular weights (between 1000 and 6000 g/mol) were used: Zdol, with OH functional end groups, and Z, with n…
A simulated annealing algorithm is applied to the reconstruction of two-dimensional porous media with prescribed correlation functions. The experimental correlation function of an isotropic sample of Fontainebleau sandstone and a synthetic correlation function with damped oscillations are used in the reconstructions.…
Based on a series of ab initio studies we have pointed out the remarkable structural stability of nanotubular and quasiplanar boron clusters, and postulated the existence of novel layered, tubular, and quasicrystalline boron solids built from elemental subunits. The present study illustrates and predicts qualitative s…
We show the design and preparation of a novel type of magnet exhibiting two compensation temperatures; i.e., the spontaneous magnetization changes its sign twice with changing temperature. The key to obtaining this unusual behavior is the simultaneous incorporation of one antiferromagnetic and two different ferromagne…
The electronic densities of states of atomically resolved single-walled carbon nanotubes have been investigated using scanning tunneling microscopy. Peaks in the density of states due to the one-dimensional nanotube band structure have been characterized and compared with tight-binding calculations. In addition, tunne…
After a series of investigations on the durable flame-retardant finishes, it was thought to be important to study these durable flame-retardant finished materials from the thermal analytical standpoint. Accordingly, cotton fabric was finished with N-methylol dialkyl phosphonopropionamide (Pyrovatex C) by thermofixatio…
The carboxyl group containing aqueous-based polyurethane (PU) dispersions were prepared from isophorone diisocyanate, poly(propylene glycol)-1000, and 2,2-dimethylol propanic acid via a PU prepolymer process. The amino content of this amino-terminated aqueous-based PU system was determined by a styrene oxide titration…