Materials Literature
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The mesomorphism of hydrogen bonded complexes formed between 4'-carboxybenzo-15-crown-5 stilbazolyl ester (CBCSE) as proton acceptor and carboxylic acids as proton donors is discussed. CBCSE is a monotropic mesogen, forming a nematic phase upon quench cooling. A total of 32 hydrogen bonded complexes has been studied.…
Abstract An analysis of the crystallization kinetics of polytetrafluoroethylene (PTFE) under nonisothermal conditions is presented. A simple method is proposed to remove the limits of the Ozawa theory. The Avramic exponent, n , can be reasonably well determined from the nonisothermal crystallization exotherm. An n val…
Hydrothermally grown crystals of alpha-K3NdSi6O15 x 2H2O, potassium neodymium silicate, have been studied by single-crystal X-ray methods. The compound crystallizes in space group Pbam, contains four formula units per unit cell and has lattice constants a = 16.008 (2), b = 15.004 (2) and c = 7.2794 (7) A, giving a cal…
Effect of sizes and dimensions on the spin density wave (SDW) and charge density wave (CDW) in organic ferromagnets was studied. It was found that the stable ferromagnetic state obtained in a closed ring with periodic boundary conditions would become unstable in an open chain due to the effect of chain ends. There was…
This paper presents a quasiharmonic model for the lattice dynamics of the ${\mathrm{Sn}}_{2}{\mathrm{P}}_{2}{\mathrm{S}}_{6}$ crystal. The model, constructed as a combination of the valence force field and the polarizable ion model with a majority of potential parameters fixed by auxiliary Hartree-Fock calculations, e…
Hydrothermally grown crystals of beta-K3NdSi6O15, potassium neodymium silicate, have been studied by single-crystal X-ray methods. Under appropriate conditions, the compound crystallizes in space group Bb2(1)m and has lattice constants a = 14.370 (2), b = 15.518 (2) and c = 14.265 (2) A. There are 30 atom sites in the…
Slow ramp-type transient-overpower tests were performed within the framework of the international CABRI-2 experimental program. The implemented power transients of ~1% nominal power/s correspond to a control rod withdrawal-type accident in a liquid-metal-cooled fast breeder reactor (FBR). The analysis of the tests inc…
The availability of xylan-type polysaccharides, representing an immense resource of biopolymers for practical application, is summarized. Xylans constitute 25–35% of the dry biomass of woody tissues of dicots and lignified tissues of monocots and occur up to 50% in some tissues of cereal grains. The most potential sou…
In this paper a comparative study of the structure, morphology, and the spectroelectrochemical response of poly (2-ethyl aniline) and polyaniline for different counterions is presented. Spongeous structure of poly (2-ethyl aniline) is obtained when mineral acids are used, while homogeneous and compact films are formed…
Diisopropyl cyclopropane-1,1-dicarboxylate ( 1 ) undergoes ring-opening polymerization in the presence of thiophenolate anions acting as initiator. A carbon-chain polymer, substituted on every third carbon atom by two isopropyl ester substituents, is obtained, whose structure and molecular weight were characterized by…
A theoretical study of light transmission through a polymer with a monolayer ensemble of bipolar nematic droplets under applied electric film is performed. The possibility of interference quenching of monochromatic coherent light directly transmitted through the film is predicted theoretically and realized in the expe…
The effect of annealing with and without applied pressure on the microstructural development and phase transformation was investigated in fine‐grained β‐SiC ceramics containing α‐SiC seeds. Materials annealed without pressure had a microstructure consisting of elongated grains, while materials annealed with pressure s…
The relationship between pore size and air permeability in two spunlaced fabrics and two spunbonded/meltblown/spunbonded (SMS) fabrics were investigated. Minimum, maximum and mean flow pore sizes were determined using liquid porosimetry. The influence of fabric weight and thickness on air permeability and pore sizes w…
Neste trabalho o efeito da adição de 2 a 7% em peso de um copolímero tribloco estireno-b-etileno-co-butileno-b-estireno (SEBS) em uma blenda polipropileno/poliestireno de alto impacto (PP/HIPS) 70:30 foi determinado. As propriedades em tração e impacto, temperatura de amolecimento Vicat e morfologia da blenda PP/HIPS…
A strong surface-enhanced Raman scattering (SERS) from TiO2 nanoparticles is firstly obtained in a nanostructural Ag–TiO2 calabash-like hybrid particle powder synthesized by γ-radiation combined with a hydrothermal treatment. Visible luminescence, due to the interband transitions of TiO2 nanoparticles, is broadened by…
The numerical performance of a finite-difference modal method for the analysis of one-dimensional lamellar gratings in a classical mounting is studied. The method is simple and relies on first-order finite difference in the grating to solve the Maxwell differential equations. The finite-difference scheme incorporates…
Optical fibres that are permanently installed in nuclear reactors (fission or fusion) or at high energy physics accelerators can accumulate considerable long-lived radiation-induced loss. Four different fibre types were irradiated up to dose values from 10/sup 3/ to 10/sup 6/ Gy and an attempt was made to reduce the r…
Melts of the alloys Al-Pd-Mn, Al-Co, and Al-Fe are containerlessly undercooled and solidified using the technique of electromagnetic levitation. The (quasi)crystal growth velocity is measured as a function of undercooling for the various phases by a high-speed infrared photosensing device. Additionally, a video image…
An experimental investigation was performed to study the rate at which strength‐controlling fatigue damage evolves in a ceramic‐matrix composite. Tensile specimens of a unidirectional SiC‐fiber‐reinforced calcium aluminosilicate matrix composite were cycled to failure or to a preselected number of cycles under similar…
Magnetic cation of Co 2+ was incorporated in a monovalent [Ni(dmit) 2 ] - (2-thioxo-1,3-dithiole-4,5-dithiolate) salt by using the supramolecular framework of 15-crown-5. The π-spins of [Ni(dmit) 2 ] - formed a one-dimensional Heisenberg antiferromagnetic linear chain, while the d-spin of Co 2+ behaved as a free S = 3…