Materials Literature
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Electron spin resonance (ESR) spectra of impurity and intrinsic defects have been measured at 4.2–295 K in Nb-doped BaTiO3 single crystals and ceramics to clarify their role in the conductivity and positive temperature coefficient of resistivity (PTCR effect). The measurements revealed a small amount of Fe3+, Cr3+, an…
Ein supramolekularer Propeller: Eine dreikernige EuIII-Helix mit sechs chiralen Bipyridincarboxylatliganden entsteht vollständig diastereoselektiv durch Selbstorganisation (siehe Bild; Eu grün, O rot, N blau). Die chiroptischen Eigenschaften dieses rotes Licht emittierenden Komplexes im Grund- und angeregten Zustand s…
In situ observation of magnetic domain structures of Pr0.5Sr0.5CoO3 was made by Lorentz electron microscopy to reveal an unusual magnetic behavior around 120K below the Curie temperature (TC∼220K). The observations in a cooling run clearly showed that the magnetic domain structure changes below about 90K and that the…
Azulenequinone derivatives have been reported to display a broad spectrum of biological activities, but study at the cellular level has been limited. The effect of twenty-seven azulenequinone derivatives on nitric oxide (NO) production by mouse macrophage-like cells Raw 264.7 was investigated in this study. All of the…
In this study, we investigate the buildup of PEI-(PSS-PAH)(n) polyelectrolyte multilayers at pH 7.4 in the presence of either NaCl or NaSCN as a supporting electrolyte. It appears that in the presence of increasing thiocyanate concentrations (from 0.1 to 0.5 M), the thickness increment, obtained from optical waveguide…
Abstract The optical anisotropies (linear dichroism or LD and birefringence) of crystalline aggregates of the sulfonic azo‐dye Ponceau SS and of dye complexed with chicken tendon collagen fibers were investigated in order to assess their polarizing properties and similarity to liquid crystals. In some experiments, the…
A facile route for in situ synthesis of Co and Ni nanoparticles in a preorganized polyacrylamide gel is reported. Metal-polymer composites were prepared by gamma-irradiation at room temperature. The Co nanoparticles were roughly 3-5 nm in size and were stable in the polymer matrix in the presence of air. The presence…
Two channels of the conductance G exist in cold-pressed powder compacts of CrO2/(CrO2∕Cr2O3), where two types of granules have different coercivities. One of the channels is the spin-dependent intergranular tunneling conductance, and the other one is the spin-independent higher-order inelastic hopping conductance. The…
[reaction: see text] Novel spiroheterocyclic molecules, namely, 2,3-dihydro-2-spiro-7'-[8'-imino-7',8'-dihydronaphthalen-1'-amine]perimidine, PNI, and 2,3-dihydro-2-spiro-4'-[8'-aminonaphthalen-1'(4H)-one]perimidine, PNO-p, were obtained by oxidation of 1,8-diaminonaphthalene using manganese dioxide. These molecules e…
Abstract A new computational approach is developed based on the mesh‐free method for the numerical simulation of shape memory alloys. A thermomechanical constitutive model is used to describe the complex material response. The incremental displacement‐based mesh‐free formulation is constructed in a total Lagrangian de…
The factors that determine the miscibility of two polymers, each of which hydrogen bonds (self-associates) to itself in the pure state, is discussed. Equations describing the contributions of hydrogen bonding to the free energy of mixing are presented. It is shown that mixtures of this type are much less likely to be…
Abstract To investigate the joint effect on shock wave propagation and attenuation in jointed rock masses, a small-scale field explosion test is analyzed numerically by using the three-dimensional discrete element method (3D DEM) and the three-dimensional finite difference method (3D FDM). Results show that rock joint…
We consider helical configurations of a cholesteric liquid crystal (CLC) sandwiched between two substrates with homogeneous director orientation favored at both confining plates. We study the CLC twist wave number q characterizing the helical structures in relation to the free twisting number q(0) which determines the…
We report a complete analysis of the formal Co 3+/4+ oxidation state in Na x CoO 2, in the interval 0.31 ≤ x ≤ 0.69. Iodometric titration and thermoelectric power confirm that a direct relationship between the Na content and the amount of Co 3+ cannot be established in this system. Creation of a significant amount of…
Aligned double-walled carbon nanotube (DWNT) long ropes with a narrow diameter distribution were directly synthesized by sulfur-assisted floating catalytic decomposition of methane. The DWNT ropes are typically up to several centimeters in length and possess good alignment and high purity. High-resolution transmission…
Abstract Thermolysis of Fe(CO) 5 and Co 2 (CO) 8 , dissolved in tetrahydronaphthalene, in the presence of aluminum trialkyl leads to uniform‐sized Fe or FeCo nanoparticles, respectively. Subsequent treatment with very dilute oxygen forms a shell which protects the metallic or alloyed core of the particles against fur…
Abstract This article presents the results of TMC and DMC polymerization with the use of acetylacetonates of low‐toxic metals: iron, zinc, and zirconium. Zinc (II) acetylacetonate proves to be a very good initiator of homopolymerization. The reaction carried out with the use of this initiator at 110 °C is very rapid a…
We report here a modular approach for the construction of a new class of compounds, the Hangman salophens. In the Hangman motif, an acid-base functionality "hangs" over the face of a redox cofactor. In contrast to more synthetically intractable porphyrin-based Hangman systems, Hangman salophens permit the facile contr…
The Seebeck coefficient of the ${\mathrm{Ti}}_{3}{\mathrm{SiC}}_{2}$ compound has recently been measured and found to be constant and negligible over a wide range of temperature. Materials with essentially zero thermopower allow us to measure the absolute thermopower of another material and could therefore be consider…
A Stokes experiment for foams is proposed. It consists of a two-dimensional flow of a foam, confined between a water subphase and a top plate, around a fixed circular obstacle. We present systematic measurements of the drag exerted by the flowing foam on the obstacle versus various separately controlled parameters: fl…