Materials Literature
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Measurements of the dynamic spall strength in aluminum, copper, and Metglas shocked by a high-power laser to hundreds of kilobars pressure are reported. The strain rates in these experiments are of the order of 107 s−1, which cannot be reached in impact experiments. The free-surface velocity behavior associated with s…
The enhanced features of a computer program (RREVM) for the estimation of copolymerization reactivity ratios using statistically sound techniques are illustrated with experimental and simulated case studies. In parallel, a literature review is given on the estimation of reactivity ratios. Both aspects are extensions b…
We study the \ensuremath{\pi}-band contribution to the optical properties of the carbon nanotubes based on the tight-binding model, including optical absorptions, optical rotatory power, and circular dichroism. By taking into account not only the interband contributions but also the free-carrier contributions, the die…
SiO 2 aerogels were prepared by a sol-gel method and supercritical drying. Introduction of nano-ZnO into nanopores of the SiO2 aerogels is performed by immersion, chemical reaction, and hydrolysis. Photoluminescence of these assemblies of nano-ZnO particles/SiO2 aerogels were systematically measured. For each assembly…
We report first-principles calculations of ${\ensuremath{\epsilon}}_{2}(\ensuremath{\omega})$ for diamond, Si, Ge, and GaAs that include the electron-hole interaction in detail. The only essential experimental input is the crystal structure of the materials. Comparison with reflectivity and ellipsometry measurements a…
Charge transport properties, including temperature-dependent dc conductivity, thermoelectric power, electron paramagnetic resonance, microwave frequency dielectric constant and conductivity, and electric-field-dependent conductance of partially crystalline (``physically'' cross-linked) HCl-doped polyaniline correlated…
Crystals of the α-(AlMnSi) (aluminium manganese silicon alloy, Al4Mn1.01Si0.74) cubic 1/1 approximant phase for the icosahedral quasi-crystal were prepared from an Al72Mn16Si12 alloy under an argon atmosphere. The structure is reproduced by the connection of two large atom clusters with icosahedral symmetry (a Mackay…
Previous studies of the structure of liquid water under pressure performed by neutron diffraction allowed us to establish two structural limits in liquid water. These two limits are closely connected to the two known forms of amorphous ice: the low-density amorphous ice (LDA) and the high-density amorphous ice (HDA).…
Catalytic oxidation of ammonia in supercritical water (SCW) was studied using a continuous-flow, packed-bed reactor at temperatures ranging from 410 to 470 °C, a nominal pressure of 27.6 MPa, and reactor residence times of less than 1 s. The kinetics and catalyst performance of MnO 2 /CeO 2 for oxidation of ammonia in…
A model of submonolayer thin film growth is studied, where the attachment of atoms to island edges is hindered by an energy barrier. A novel behavior of the density of islands, N_s, is predicted as a function of flux F and temperature T. For example, N_s scales as F^X with X=2i^*/(i^*+3), where i^* is the critical isl…
The flattening of a crystal cone below its roughening transition is studied by means of a step flow model. Numerical and analytical analyses show that the height profile, h(r,t), obeys the scaling scenario dh/dr = F(r t^{-1/4}). The scaling function is flat at radii r
Polyhydroxyalkanoates (PHAs) are a class of carbon and energy storage polymers produced by numerous bacteria in response to environmental limitation. The type of polymer produced depends on the carbon sources available, the flexibility of the organism's intermediary metabolism, and the substrate specificity of the PHA…
Studies on structure and electronic properties of amorphous nitrogenated carbon films prepared in dual electron cyclotron resonance–radio frequency plasma from a mixture of methane and nitrogen are presently reported. These films are characterized by Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy,…
A novel method, in situ polymerization, was used for the preparation of nylon 6/silica nanocomposites, and the mechanical properties of the nanocomposites were examined. The results showed that the tensile strength, elongation at break, and impact strength of silica-modified nanocomposites exhibited a tendency of up a…
We demonstrate that the limits of drawing of fibre can be pushed down to nanometre dimensions. By a process similar to dry-spinning, nanofibres can be drawn with ultimate dimensions comparable with the ones of single-wall carbon nanotubes. An important difference with tubes is that our nanofibres are produced one at a…
The characteristics of the thin films of silica−alkyltrimethylammonium chloride mesostructured materials have been investigated by means of the fluorescence of pyrene as well as the infrared spectra at variable temperatures. Pyrene molecules were incorporated in the hydrophobic part of the silica−surfactant mesostruct…
The out-of-plane and in-plane distortions of a series of nickel(II) meso-substituted porphyrins with 0, 1, 2, or 4 tert-butyl groups [nickel(II) porphine (NiP), nickel(II) mono-tert-butylporphyrin (NiMtBuP), nickel(II) di-tert-butylporphyrin (NiDtBuP), and nickel(II) tetra-tert-butylporphyrin (NiTtBuP)] are investigat…
The equilibration of spherical micelles formed by polystyrene−poly(2-vinylpyridine) (PS−PVP) diblock copolymers in toluene is studied by means of cryo electron microscopy. The evolution of the micelles in order to reach the equilibrium state involves the transformation of their structure and size and requires a consid…
Manganese-based perovskites have been successfully synthesized using deposition by aqueous acetate solution (DAAS). This novel technique, which has the potential for depositing large area thin films with high throughput and low cost, involves the preparation of stoichiometric mixtures of metal−acetate precursor soluti…
We have synthesized metallocene−porphyrazine (pz) complexes, as shown, and find them to be highly electroactive with five reversible redox couples. X-band EPR measurements of the (2H)−Mo(V) complex indicate that spin delocalization from the Mo(V) to the pz−dithiolene is significantly greater than for classical dithiol…