Materials Literature
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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…
[Fe(L)Cl] 2 (L = N-(4-methylphenyl)-3-methoxy-salicylaldimimine) was synthesized and its crystal structure determined. [C 30 H 26 Cl 2 Fe 2 N 2 O 6 ], triclinic, space group P 1̄ , a = 9.278(2), b = 9.4050(10), c = 10.489(2) Å , α = 64.43(2), β = 74.540(10), γ = 62.40(2)° , V = 729.1(2) Å 3 , Z = 1. Two identical [Fe(…
This paper discusses a technique for estimating the Preisach function of a soft magnetic material from symmetrical magnetizing processes. Utilizing the independence of the "up" switching process from the "down" switching process, it is possible to identify the Preisach function with a single derivative.
Periphytic diatom communities are important primary producers in streams where their characteristics are influenced by many environmental factors. To study and cut off real effects of metal pollution on these communities, complementary experiments were performed in order to precise short term effects of pollution duri…
The effect of application of cellulose-based edible coating, hydroxypropyl methylcellulose (HPMC) to mature-green tomatoes on the firmness and color was investigated. Tomatoes were stored at 20 degrees C for up to 18 days. Firmness decreased as storage time increased in all treatments. However, application of HPMC edi…
The degradations of phenol in air-equilibrated aqueous media were investigated using coupled sonochemistry and Fenton's reagent for a variety of operating conditions. The decomposition yields of phenol (100-500 microM) were substantially enhanced due to the addition of Fenton's reagent (FeSO4 into the solutions irradi…
The numerical simulation of the absorption and scattering cross sections of vanadium dioxide nanoparticles with silver and gold shells are presented. The cross sections are evaluated for the spectral intervals 1–1.2, 1.3–1.7, and 9–12 µm both before and after the semiconductor-metal phase transition in VO 2 . It is de…
The water absorption behaviour and the effects of ageing on the mechanical properties of short sisal fibre reinforced polystyrene composites have been studied with special reference to fibre loading and fibre-matrix interface modification. The composites were subjected to different ageing conditions viz., immersion in…
Based on the results of fracture in polymethyl methacrylate and a spheroplastic using a magnetic-pulse setup, the specific work of the formation of a new surface is estimated, which is similar to Griffith’s surface energy for quasi-static tests. The value obtained is greater than the corresponding value determined fro…
A new scheme of modified embedded atom method (MEAM) is proposed in this paper. The analytic form of the embedding function is modified. All the parameters of MEAM have been reset by relating them with bulk properties and some non-bulk properties, for example, the bond length of a dimer and the change of surface inter…