Materials Literature
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Alternating current impedance, Fourier transform Raman/infrared (IR), and luminescence excitation (continuous and time-resolved) measurements have been conducted on solutions of poly(propylene glycol) (MW 4000) complexed with Eu[N(CF3SO2)2]3 salt, EuTFSI3, along with differential scanning calorimetry (DSC) studies. Fr…
To identify key parameters which influence the efficiency of nonenzymatic template-directed oligonucleotide reactions, a kinetic study of oligoguanylate synthesis on a polycytidylate (poly(C)) template has been performed. This oligomerization is satisfactorily described by three kinetic processes: (i) dimerization to…
We report measurements of the resistivity, thermopower, thermal conductivity, Hall coefficient, and magnetic susceptibility of ${\mathrm{RuAl}}_{2}$ over a wide temperature range. Room-temperature sound velocity measurements are also reported. We find that at low temperature ${\mathrm{RuAl}}_{2}$ behaves as a low carr…
Iron samples of different thicknesses have been submitted to laser shocks of short duration. Transmitted wave measurements have been performed by means of polymeric piezoelectric transducers. The records indicate a decrease of the elastic precursor amplitude with increasing propagation distance, as well as a stress re…
Nonlinear optical properties of a fixed molecular dimer, 2,2′-diamino-7,7′-dinitro9,9′-spirobifluorene (ANSF), have been investigated in solution by the degenerate four-wave mixing technique. It has been observed that the orientationally averaged second molecular hyperpolarizability of ANSF in THF is enhanced ten time…
Dynamically vulcanized poly(vinyl chloride)/epoxidized natural rubber (PVC/ENR) thermoplastic elastomers (TPEs) were prepared with a Brabender plasticorder coupled with a mixing attachment by melt mixing. The blends were prepared at 150°C at a rotor speed of 50 rpm. Curatives concentration was steadily increased from…
It has recently been shown that well-ordered ${\mathrm{Fe}}_{3}{\mathrm{O}}_{4}(111)$ films can be prepared epitaxially on clean Pt(111) surfaces; various techniques have indicated that these multilayer films are chemically identical to bulk single crystals. We have studied the electronic structure of such an ordered…
Angle-resolved photoemission spectroscopy (ARPES) measurements on ${\mathrm{NiS}}_{2\ensuremath{-}x}{\mathrm{Se}}_{x}$ single crystals show the evolution of a narrow band near the Fermi level, which develops in the vicinity of the correlation-driven metal-insulator transition. To model the metal-insulator transition,…
We show that epd (gapB) mutants lacking an erythrose 4-phosphate (E4P) dehydrogenase are impaired for growth on some media and contain less pyridoxal 5'-phosphate (PLP) and pyridoxamine 5'-phosphate (PMP) than their epd+ parent. In contrast to a previous report, we found that gapA epd double mutants lacking the glycer…
The magnitudes and orientations of the principal elements of the 15 N chemical shift and 1 H− 15 N dipolar coupling interaction tensors pertaining to the glycine residue in 15 N -acetyl glycine (NAG) and [ 15 N-Gly]collagen were determined by the analysis of one-dimensional dipolar chemical shift powder patterns. A on…
Isothermal crystallizations from the melt of samples of syndiotactic polypropylene having different degrees of syndiotacticity have been performed. The thermal behavior and the structural features of the melt-crystallized samples have been analyzed by differential scanning calorimetry and X-ray diffraction. According…
A disordered three-dimensional perovskite phase SrTa2-xNbxO6 (x = 0, 0.2, 0.4) is formed by topochemical dehydration of acid-exchanged Ruddelsden Popper compounds K2SrTa2-xNbxO7. The metastable perovskite is a stoichiometric precursor to the structurally unrelated, stable tetragonal tungsten bronze phase. Dehydration…
Chitosan fibers were wet spun from a 6% by weight chitosan in 3% by volume acetic acid solution. The fibers were collected as a 20 filament yarn intended for use as a chaff substrate. The yarn had to be sufficiently dry following spinning to allow for winding and subsequent separation of the filaments. Drying of the y…
Temperature dependence of absorption spectra for thin films of doped manganites ${R}_{0.6}{\mathrm{Sr}}_{0.4}{\mathrm{MnO}}_{3},$ where $R$ is a rare-earth atom, has been investigated by systematically changing the averaged ionic radius $〈{r}_{A}〉$ of perovskite $A$ site. We have observed a specific absorption band at…
The irreversible polymerization of a monomer liquid has been studied by molecular-dynamics simulation in two and three dimensions. The growth process is studied under good solvent conditions in the dilute regime and up to semidilute and concentrated regimes. In the dilute regime we observe a reaction limitation due to…
We show that photoluminescence from a thin silicon-on-insulator (SOI) layer with a thickness of about 0.1 μm excited by ultraviolet (UV) light originates from the recombination of electrons and holes in their condensed phase. The UV excitation increases the density of electrons and holes in the SOI layer, since the UV…
Mesoporous silica, SBA-2, has been investigated by using high-resolution transmission electron microscopy supported by computer image simulations. The complete pore structure connecting the discrete supercages of which the silica is composed has been determined. In addition, unexpected well-defined cubic-hexagonal (po…
A tight-binding model is used to investigate confinement and shape effects on the optical absorption spectrum of CdSe nanocrystals up to 5 nm diam. The effects of size dispersion are studied and we show that to simulate the spectrum of a collection of nanocrystals it is not always sufficient to broaden inhomogeneously…
The voltage and film composition dependence of leakage currents of ferroelectric SrBi2Ta2O9 thin films, sandwiched between Pt has been studied. Schottky emission dominated the leakage current at voltages above the ohmic conduction regime, while space charge limited currents (SCLC), for which the observed temperature d…
Nitrogenated and hydrogenated amorphous carbon (a-C:H:N) films have been deposited by a plasma beam source using a gas mixture of C2H2, Ar and N2. The Ar/C2H2 ratio is kept constant at a ratio of 3, with the nitrogen flow allowed to vary. Nonnitrogenated films, with Ar/C2H2 ratios of 3 and 6 were also deposited and an…