Materials Literature
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A composite material is produced by using polyester textile wastes as reinforcement material and mainly urea formaldehyde as matrix material. This composite is used in banks, tables, shelves, and pots. The bending strength and absorption properties of the textile reinforced composite are investigated and compared with…
It has been shown that the photoluminescence (PL) intensity of a porous silicon (PS) sample, covered by a thin SiC film is six times larger compared with the initial PS subjected to rapid thermal annealing (RTA), and a strong up-shift (∼100 nm) is observed relative to the non-treated PS + SiC sample. Clustering proces…
The depth of radiological contamination is information required for decontamination and decommissioning of nuclear facilities. This paper proposes and tests a simple technique for measuring the depth of contamination. The method uses measurements with an HPGe detector at two distances (or heights) from the surface on…
The effective thermal conductivity κ eff of seven opal + epoxy resin nanocomposite samples with 100% filling of first-order pores by epoxy resin was measured in the 100-to 300-K temperature interval. In the nanocomposite studied, the thermal conductivity of the matrix (amorphous SiO 2 spheres) is larger than that of t…
The effect of atomic ordering on displacive-type structural phase transitions is considered for crystals with several atomic sublattices. On the basis of group-theoretical analysis and general crystallographic and thermodynamic principles, it is shown that ordering gives rise to qualitative restructuring of phase diag…
The properties of Cr 3+ -doped Li 2 Ge 7 O 15 (LGO) lithium germanate nanocrystals produced in lithium germanate glasses under isothermal heating were studied. The samples were characterized by x-ray diffraction and small-angle scattering, as well as by transmission electron microscopy. The luminescence spectra of the…
Zinc vaporization of Mn‐Zn ferrites was quantitatively characterized in terms of oxygen partial pressure P O2 , temperature, grain size and sample geometry. The amount of zinc loss was measured as a function of time at various temperatures by a thermogravimetric method. The weight loss due to irreversible zinc vaporiz…
Abstract The reaction between [Mn(MAC)(H 2 O) 2 ]Cl 2 ·4H 2 O and LiTCNQ (MAC = 2,13‐dimethyl‐3,6,9,12,18‐pentaazabicyclo[12.3.1]octadeca‐1(18),2,12,14,16‐pentaene) affords a complex with the formula [Mn(MAC)(TCNQ) 2 ] ( 1 ), whose crystal structure has been determined. Its structure consists of neutral mononuclear en…
Water in well-mixed ponds containing photosynthetic algae has been observed to have an extremely high Dissolved Oxygen (DO) content. Up to four times saturation levels of DO have been recorded. Since DO is known to have an important role in the photocatalytic oxidation of organic contaminants in water, it was hypothes…
In 1684 Members of the Royal Society of London discussed the nature of a type of woven cloth described as incombustible linen, or salamander's wool. It was an attempt to explain scientifically the phenomenon described in many cultures over more than 1,500 years, of a cloth which could be immersed in fire and emerge, n…
This paper is part of a Ph.D. thesis at Universidade Federal do Rio Grande do Sul A new centric diatom, Paralia elliptica Garcia, is described from marine surface sand collected in Zimbros Bay, Araçá, Penha, Praia Brava and Taquarinhas (Santa Catarina State, Brazil), where it lives as an epipsammic species. The taxon…
The quantum confinement model, which assigns some of the luminescence features in porous silicon to size quantization in Si nano-crystallites, also predicts quantization of both the conduction and valence bands into sub-levels. In order to resolve this effect we have used a new experimental technique called “photo-ind…
Aluminosilicate sodalites of three different types--chlorosodalite, basic sodalite, and oxalate sodalite--have been synthesized in their sodium forms using hydrothermal synthesis. The syntheses were investigated in terms of their relative rates of crystallization and final crystallinities using powder X-ray diffractio…
A novel knife edge (KE) for measurement of the electron beam (EB) diameter was made and evaluated. To screen off electrons scattered at the edge, the Si KE has a `visor' made of Ta, which is formed in a body and aligned with the KE. Monte Carlo simulation revealed that the scattering electrons are not negligible to ac…
A theoretical approach to the description of phase transition kinetics in the low-temperature phase of relaxors is put forward. The idea underlying the approach consists in the local direction of spontaneous polarization in relaxors being pinned by bound charge carriers. Strong electric fields gradually activate the l…
The methods of atomic force microscopy and optical absorption spectroscopy are applied to study the effect of microwave treatment on the properties of SiO 2 /SiC structures obtained by rapid thermal annealing and conventional thermal oxidation in steam. From the variation of the sample optical density with total time…
Abstract We developed stressed liquid crystal (SLCs) films consisting of unidirectionally oriented domains of liquid crystal separated with polymer chains for use in electrically controlled phase retardation devices. Performance of this new electro‐optical material makes them an ideal candidate for use in high‐speed d…
We present experimental data on the low-frequency noise in vanadium dioxide based sandwich and planar structures possessing negative differential resistance. It is established that the noise spectrum obeys the 1/ f α law and the values of coefficient α for the sandwich structure are experimentally determined for the f…
The removal of radionuclides such as 129 I and 131 I from radioactive liquid wastes was studied. Two natural zeolites were modified with different quaternary alkylammonium ions to replace the exchangeable cations from the zeolite surface and used as adsorbent materials. The quaternary ions used for such purpose were h…
We have made a number of high quality porous silicon microcavities operating in the visible and near infrared regions with a FWHM of less than 2 nm. This is achieved through the low temperature anodic oxidation of highly doped p-type silicon wafers. Reduced interface fluctuations and very large porosity modulations ar…