Materials Literature
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Polycaprolactone/poly(ethylene oxide)/polylactide tri-component copolymers (PCEL) with different compositions were synthesized by copolymerization of epsilon-caprolactone and L-lactide in the presence of poly(ethylene glycol) using stannous octoate as a catalyst. The copolymers were purified and characterized by vario…
Rheological properties of cellulose fibrous suspensions were measured with a cone-plate type rheometer. Effect of particle concentrations, c, and salt concentrations of the systems on the properties were studied. The flow curve of the fully dialyzed system showed Newtonian flow at a particle concentration of 0.1 wt%.…
The effect of a magnetic field on the formation of structural domains at martensitic transition in the intermetallic system Ni/sub 2+x/Mn/sub 1-x/Ga was studied. For the compositions x whose temperatures of structural and magnetic transitions are close this effect is most pronounced. In the field of 0.2 to 1 T the inc…
Because retinyl palmitate was reported to be more stable to oxidation than retinol, we wondered if retinyl palmitate was also more resistant to photolysis as compared to free alcohol. We investigated the resistance of ethanolic solutions of retinol, retinyl palmitate, or both to air oxidation and (or) photolysis using…
Abstract The oriented association of two or more polytypes of the same compound enters neither in the Friedel's definition of twinning nor in that of epitaxy/syntaxy; for it the term allotwinning is here introduced and the relevant laws of formation are established. The appearance of allotwins is in principle recogniz…
The ferroelastic symmetry changes of the lead-based complex perovskite PbFeY 0.5 Ta 0.5 O 3 are investigated by means of single crystal x-ray diffraction and observations in polarized light microscopy at different temperatures. The position of the 400 and 222 cubic reflections is followed between 80 K and 300 K. Resul…
CeVO 4 prepared via the sol‐gel route with a tetragonal ( I 4 1 / amd ) crystal structure was found to act as an ion‐storage material. The structure of powders and films having different Ce / V molar ratios was determined using X‐ray diffractometry. Cyclic voltammograms of films allowed for distinguishing between the…
Raman spectra of molten ThCl4–ACl (A = Li, Na, K or Cs) mixtures have been measured. The complete composition range has been studied for all systems at temperatures up to 960 °C. The spectral changes upon melting the binary compounds A2ThCl6, A3ThCl7 and the pure crystalline ThCl4 were also measured. The data indicate…
This article examines the effects of dispersed phase concentration, processing apparatus, viscosity ratio, and interfacial compatibilization using an SAN–amine compatibilizer on the morphology of blends of bisphenol A–polycarbonate (PC) with styrene–acrylonitrile (SAN) copolymers. For uncompatibilized blends, the disp…
Liquid crystalline 1,1′∶4′,1″-terphenyls with three and four lateral fluoro substituents and alkyl or alkoxy substituents in the 4- and 4′-positions have been synthesised. Synthetic strategies employed were convergent and involved the use of arylboronic acids and aryl halides in palladium-catalysed cross-coupling reac…
A diradical consisting of two polychlorinated triphenylmethyl radical units connected by a 1,1′-metallocenylendivinylene bridge has been synthesized and characterized; EPR frozen solution experiments down to liquid helium temperature showed that the organometallic unit acts as a ferromagnetic coupler.
Structure, magnetic and transport properties of manganites have been studied. Samples with show ferromagnetic behaviour. For higher concentrations an important influence of antiferromagnetic interactions has been observed. The sample shows an antiferro-ferromagnetic transition induced by the applied field and the comp…
A new model which extends previous studies and includes the interaction between enveloping gas and an array of droplets has been developed and presented in a previous paper. The model incorporates the probability density function of atomized metallic droplets into heat transfer equations. The main thrust of the model…
In situ XAFS spectroelectrochemistry is used to characterize the oxidation state and coordination environment of cerium in two different heteropolytungstates, the Wells–Dawson [Ce(α-2-P2W17O61)2]17– anion, and the Preyssler [CeP5W30O110]12– anion. Ce(III), coordinated to the Wells–Dawson framework, is oxidized at an a…
The self-associated structures of two noble meso-(monopyrazolyltritolyl)porphyrins synthesized via their NH-protected precursors have been studied by 1H NMR, FT-IR and ESI MS measurements; meso-(pyrazol-4-yl)porphyrin and meso-(3,5-dimethylpyrazol-4-yl)porphyrin form a dimer and a tetramer, respectively, in solution d…
The volume changes of poly(2‐methylaniline) upon redox cycling in different acidic media was studied using voltammetric experiments with simultaneous microscopic observation. These experiments were performed during continuous potential cycling and also when the polymer film was completely reduced and relaxed. The chan…
The zero-field ${}^{139}\mathrm{La}$ nuclear magnetic resonance (NMR) was studied in polycrystalline ${\mathrm{La}}_{1\ensuremath{-}x}{\mathrm{Ca}}_{x}{\mathrm{MnO}}_{3}$ for $0.125<~x<~0.5$ to investigate magnetic phases in ordered states. The main result of this work is that mixed states are found near any pha…
The field distribution of DC insulation systems is controlled by the conductivity κ of the insulation material. It can be improved by using a high resistance surface coating. Furthermore this coating can prevent charge accumulation on the surface of the insulation. This paper reports about the investigations regarding…
The 1H NMR spectra of the 5,10,15,20-tetraalkylporphyrins 2–4 reveal a large downfield shift of the signal for the NH protons and a reduction in the activation energy for NH tautomerism as the alkyl substituents become larger; these unusual changes can be rationalized in terms of greatly enhanced intramolecular hydrog…
Separation of methylalumoxane (MAO) by adsorption on siliceous porous materials with different average pore diameters has been carried out; polymerization of ethylene was conducted with Cp2ZrCl2 using the separated MAO as cocatalyst, it was found that the MAO adsorbed on MCM-41 with average pore size of ca. 25 Å is ve…