Materials Literature
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The seeded and unseeded precipitation of calcium carbonate from supersaturated aqueous solutions was investigated in a closed system under conditions of constant supersaturation (supersaturation 1.88−3.39) at 25 °C and at pH 9.0 and 10.0. The analysis of our results based on expressions for the supersaturation depende…
Solubilities of four heavy n -alkanes (tricosane, pentacosane, hexacosane, and octacosane) in a solvent containing seven atoms of carbon (heptane, methylcyclohexane, and toluene) are determined by simple thermal analysis. It is shown that the nature of the solvent has no major influence on the solubility and that, in…
2-Oxo-hept-4-ene-1,7-dioate hydratase from Escherichia coli C converts 2-oxo-hept-4-ene-1,7-dioate to 2-oxo-4-hydroxy-hepta-1,7-dioate by the addition of water using magnesium as a cofactor. The enzyme is one of a set of inducible enzymes, known collectively as the homoprotocatechuate meta-fission pathway. The entire…
Mesoporous silica fibers with accessible, highly ordered large periodic pores are directly drawn from a highly viscous surfactant/silicate solution. Poly(ethylene oxide)-b-poly(propylene oxide)-b-poly(ethylene oxide) triblock copolymers are used as the structure-directing agents under acidic conditions during the synt…
Ultrathin films have been prepared by self-assembling trioctylphosphine oxide, TOPO, capped n-type 20−40 Å diameter CdSe nanoparticles and 1,6-hexadecanethiol, HDT, onto p-doped semiconducting polymers, chemically deposited poly(3-methylthiophene), PMeT (for Device A ), and electrochemically deposited poly(pyrrole), P…
Dynamical stability of the crack front line that propagates between two plates is studied numerically using the simple two-dimensional mass-spring model. It is demonstrated that the straight front line is unstable for low speed while it becomes stable for high speed. For the uniform model, the roughness exponent in th…
Low temperature absorption spectra of doped , and single crystals, grown by the flux method, are reported. A simulation of the energy level scheme is carried out. The effective Hamiltonian includes elementary interactions such as coulombic, spin-orbit, two- and three-body interactions. The crystal field effect is intr…
We investigate the temperature-dependent optical conductivity of ${\ensuremath{\alpha}}^{\ensuremath{'}}\ensuremath{-}{\mathrm{NaV}}_{2}{\mathrm{O}}_{5}$ in the energy range 4 meV--4 eV. The intensities and the polarization dependence of the detected electronic excitations give a direct indication for a broken-parity…
During the STS-83 Spacelab mission, a sample of Pd78Cu6Si16 was processed in the electromagnetic levitation facility TEMPUS. Surface oscillations of the levitated liquid droplet were excited, and frequency and damping of the oscillations were observed. Under microgravity conditions, the damping constant is simply rela…
Time-resolved photoluminescence (PL) spectra are reported for gas-suspended 1–10 nm diameter SiOx particles formed by laser ablation of Si into 1–10 Torr He and Ar. Three spectral bands (1.8, 2.5 and 3.2 eV) similar to PL from oxidized porous silicon were measured, but with a pronounced vibronic structure. Particle si…
We report on the synthesis of size-classified PbS nanocrystals by differential mobility analysis of a polydisperse aerosol formed by nucleation and aggregation processes in a furnace reactor. The sublimation temperature employed is below the stoichiometric evaporation temperature, thus enabling direct and simple synth…
General properties of nucleation of elastic defects in crystals undergoing a phase transition are described in the framework of a Landau-type approach. For static defects the phase diagram topology of a nucleus is shown to be independent of the nature and geometry of the defects and may contain additional phases which…
We have measured the dielectric loss in SrTiO3 thin films grown on SrRuO3 electrode layers with thickness ranging from 25 nm to 2.5 μm. The loss depends strongly on the thickness but differently above and below T≈80 K: as the thickness increases, the loss decreases at high temperatures but becomes higher at low temper…
We report Mn $K$-edge extended x-ray absorption fine structure spectra on ${\mathrm{La}}_{0.75}{\mathrm{Ca}}_{0.25}{\mathrm{MnO}}_{3}$ up to high momentum transfer across the metal-insulator $(M\ensuremath{-}I)$ transition. The data show compelling evidence for (i) large or intermediate Jahn-Teller polarons (IJTP), ch…
We report the results of magnetic measurements on a powder sample of NiCu(pba)(D_2O)_3 \cdot 2D_2O$ (pba=1,3-propylenebis(oxamato)) which is one of the prototypical examples of an $S$=1/2 and 1 ferrimagnetic chain. Susceptibility($χ$) shows a monotonous increase with decreasing temperature (T) and reaches a maximum at…
We have carried out angle resolved photoemission spectroscopy of ${\mathrm{SmTe}}_{3}$, a quasi-two-dimensional material with an incommensurate high-temperature charge density wave (CDW). This is the first direct experimental view of the full detail of an imperfectly nested Fermi surface, and the momentum space gap an…
Ab initio Perturbed Ion cluster-in-the-lattice calculations of the impurity centers NaI:Tl+ and CsI:Tl+ are pressented. We study several active clusters of increasing complexity and show that the lattice relaxation around the Tl+ impurity implies the concerted movement of several shells of neighbors. The results also…
Cu-, Eu-, or Mn-doped ZnS nanocrystalline phosphors were prepared at room temperature using a chemical synthesis method. Transmission electron microscopy observation shows that the size of the ZnS clusters is in the 3–18 nm range. New luminescence characteristics such as strong and stable visible-light emissions with…
A sample of poly(vinyl chloride) (PVC) and a polar plasticizer consisting of dioctylphthalate (DOP) and triisopropylphenylphosphate (TIPPP) was prepared and found to possess some electrical conductivity. Different samples of PVC compositions were formulated from the PVC-DOP-TIPPP system and also variable proportions o…
Novel pressure-induced intercalation of alcohols into a layered titanate has been discovered using a diamond-anvil cell and in situ X-ray diffraction measurement. The lepidocrocite(γ-FeOOH)-type titanate containing pentylammonium ions exhibited uniaxial expansion of 0.27 nm in methanol at 1 GPa and 0.23 nm in ethanol…