Materials Literature
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We report the structural, magnetic and electron transport properties of a new series of compounds where we have substituted Al 3+ in the Mn site of rhombohedral, cation deficient LaMnO 3+ . All the samples crystallize in rhombohedral ( R c ) symmetry with minimal changes in lattice parameters. Mn 4+ content gradually…
Thermally stimulated creep recovery (TSCR) experiments have been used to study the influence of tacticity on the α retardation process in amorphous poly(methyl methacrylate) (PMMA). The α retardation process associated with the glass transition is strongly dependent on tacticity. The high-sensitivity TSCR−fractional l…
Laser-ablated iron, cobalt, and nickel atoms, cations, and electrons have been reacted with NO molecules during condensation in excess neon and argon. The end-on bonded Fe(NO) 1 - 3, Co(NO) 1 - 3, and Ni(NO) 1 - 2 nitrosyls and side-bonded Fe−(η 2 -NO), Co−(η 2 -NO), and Ni−(η 2 -NO) species are formed during sample d…
The nature of the superionic transition in Ag2 HgI4 and Cu2 HgI4 has been investigated using temper dependent powder neutron diffraction and impedance spectroscopy techniques. In the case of Ag2 HgI4 , the superionic transition occurs at Tc = 326(2) K and is accompanied by a 50-fold increase in the ionic conductivity.…
The Gibbs canonical distribution, d w ~ exp ( - E ( p , q ) / k B T ) d p d q , seems one of the most solid pillars of statistical physics. Thermodynamics is believed to be a derivative of this distribution. Since the temperature T is introduced, de facto , from a heat bath by the zeroth law of thermodynamics, this di…
The reaction kinetics over a V 2 O 5 −WO 3 /TiO 2 catalyst which can describe the NH 3 slip from a selective catalytic reduction (SCR) reactor as well as the maximum conversion of NO over a wide range of reaction temperatures was developed to design the SCR process. The modeling of the reactor based upon the kinetics…
To produce high-performance poly(ethylene terephthalate) (PET) composites from the polymerization of ethylene terephthalate cyclic oligomers (ETCs) prepared from PET waste, the viscosity, thermal stability, and crystallization of ETC melts were investigated, and ETC melt was polymerized with cyclic dibutyltin initiato…
As part of a wider effort to develop a new class of waterborne coatings, hybrid miniemulsion polymerization was carried out with acrylic monomers (methyl methacrylate, butyl acrylate, and acrylic acid) in the presence of oil-modified polyurethane resin. Latexes with different ratios of resin to acrylic monomers were s…
In this article, we report on the effect of using ultrasound during emulsion polymerization. This work differs somewhat from that previously reported in that ultrasound is used in conjunction with conventional initiators. The aim is to observe the changes in the nature of polymerization and the synthesized polymer. In…
Gelatin was chemically modified by crosslinking samples with one of a number of bifunctional reagents as was done earlier in a processing technique used to improve mechanical properties through chain orientation. The effects of this crosslinking on the biodegradability of the resulting films were evaluated in the labo…
The sorption and diffusion of water vapor in poly(ethylene terephthalate) (PET) film were measured by applying a thermogravimetric analyzer (TG-DTA), which customarily has been used to detect the weight loss of a sample with the increase of temperature under a given atmosphere. In this case, we detected the weight gai…
A resin with a high refractive index and a high Abbe number can be produced by radical polymerization of a polymerizable monomer mixture composed of essentially sulfur-containing aromatic methacrylates. An optical material composed of said resin is provided especially for lenses. © 2000 John Wiley & Sons, Inc. J Appl…
Coordination of para- substituted pyridines 4-X-C 5 H 4 N (where X = NMe 2, CMe 3, H, COMe, CN) to metal carbonyl moieties such as “ cis- M(CO) 2 Cl” (M = Rh(I), Ir(I)) and “ fac- Os(CO) 3 Cl 2 ” produces an enhancement up to about 2 orders of magnitude of the quadratic hyperpolarizability β λ of the free pyridine. Th…
Continuous, slow addition of AB 2 monomer (3,5-diiodophenylacetylene) to a solution of a multifunctional core results in high molecular weight hyperbranched phenylacetylene polymers with narrow polydispersites. Control over the molecular weight ( M w = 8−90 kDa) was achieved by varying the monomer:core ratio from 17.5…
[Fe(btzp)3](ClO4)2 (btzp = 1,2-bis(tetrazol-1-yl)propane) represents the first structurally characterized Fe(II) linear chain compound exhibiting thermal spin crossover. It shows a very gradual spin transition (T1/2 = 130 K) which has been followed by magnetic susceptibility measurements and 57Fe Mössbauer spectroscop…
The secondary crystallization and its influence on the glass transition are studied as a function of crystallization temperature and time by differential scanning calorimetry for PEEK. The multiple melting behavior resulting from isothermal annealing from the glass or crystallization from the melt is discussed in the…
ADVERTISEMENT RETURN TO ISSUEPREVCommunication to the...Communication to the EditorNEXTSoluble Polyimides from Unsymmetrical Diamine with Trifluoromethyl Pendent GroupIm Sik Chung and Sang Youl KimView Author Information Center for Advanced Functional Polymers, Department of Chemistry and School of Molecular Science (…
The magnetization curves as a response of sweeping magnetic field in the thermal environment are investigated using the quantum master equation. In a slow velocity region where the system almost behaves adiabatically, the magnetic plateau appears which has been observed in the recent experiment of V$_{15}$ [ Phys. Rev…
We describe a theoretical study of the role of adsorbate interactions in island nucleation and growth, using Ag/Pt(111) heteroepitaxy as an example. From density-functional theory, we obtain the substrate-mediated Ag adatom pair interaction and we find that, past the short range, a repulsive ring is formed about the a…
We calculate the electronic and optical excitations of polythiophene using the GW approximation for the electronic self-energy, and include excitonic effects by solving the electron-hole Bethe-Salpeter equation. Two different situations are studied: excitations on isolated chains and excitations on chains in crystalli…