Materials Literature
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The industrial demand for gold has remained relatively static over the past decade and is a small proportion of total gold demand. Current applications are briefly reviewed and the prospects for future growth discussed. It is evident that substantial growth in demand will come only from the development of new applicat…
An optical microscopy investigation of the SmA phase close to the nematic phase puts into evidence the interaction between focal conic domains on one hand, screw and edge dislocations on the other hand. We report here three different situations of such interactions. Our results point towards a dislocation model of the…
A single-shot optical pump-and-probe test system is reported. The system is designed for thermal characterization of thin-film samples that can change their phase state under the influence of a short and intense laser pulse on a subnanosecond time scale. In combination with numerical analysis, the system can be used t…
We have developed a gas sensor for hydrocarbons using layered structures hydrocarbons/porous silicon. Sensitivity of this device, response time and capacitance response to different gases (ethane, ethylene and propane) have been studied. DC and AC electrical measurements were performed to test the sensor and it has be…
Óxido de cério com partículas de tamanho nanométrico foi preparado pela técnica da precipitação utilizando como agente precipitante o hidróxido de amônio ou o ácido oxálico. O principal objetivo deste trabalho foi a obtenção de pós nanométricos de CeO2 com altos valores de área de superfície específica. Os pós calcina…
We propose a novel microlens array structure in a homeotropic liquid crystal (LC) configuration. The symmetry of molecular ordering in the homeotropic alignment on a circular surface relief structure provides the polarization independent focusing characteristics of the LC microlens. The surface relief structure of pol…
Reactions between a tripodal trithiaether-triamine and the monomethoxycarbonylmethyl ether of p-tert-butylcalix[4]arene led to the ready isolation of both di- and triamides, namely di- and tricalixaryl derivatives of the tripod. These molecules, designed as dendrimer precursors, retain a core capable of acting as a mu…
In this experimental study, the effects of pile length on abrasion resistance of chenille fabrics were investigated. In order to monitor the effect of pile length, we produced chenille yarn samples with different pile lengths of 0.7, 0.8, 1, 1.2 mm and wove them into upholstery fabric. Then, the fabric samples were su…
In order to investigate the reciprocal interaction between a SFCL and the Power System an equivalent circuit of the device needs to be introduced in a power system simulator. In this paper the equivalent circuit of a magnetic shield type SFCL, consisting of two coupled electric and thermal networks, is obtained starti…
Abstract Absorption of infrared radiation in the porous silicon (PS) films prepared by common electrochemical etching in DF‐ethanol‐D 6 solutions was studied. We report our results of the effect of deuterium termination on the process of surface states changes of the PS after their exposure to ambient air for few mont…
The luminescent properties of Er 3+ ions embedded in silicate glass matrices with F, N, K, Al, P, Ge, P + Al, P + K, and Ge + Al admixtures are studied. Glass samples with an erbium concentration of up to 9 × 10 20 cm −3 are synthesized by plasma-assisted CVD. The spectra, kinetics, and relative quantum efficiency of…
A family of meta octa-substituted 5,10,15,20-tetraphenylporphyrin derivatives and their metal ( Cu(II) and Zn(II) ) complexes were examined by electrochemical studies. These functionalized MTPPs exhibited a dramatic anodic shift (>200 mV ) in their first ring redox potentials relative to the para-phenyl substituted…
Third-order optical nonlinearities of several polymer films doped with naphthalocyanine derivatives have been measured under resonant conditions by femtosecond degenerate four-wave mixing (DFWM). The metal substitution and the peripheral groups influence both the magnitude and the response of the third-order optical n…
On the Ag(111)-p(4x4)-O surface SO2(g) reacts with oxygen according to SO2(g)+O(a)-->SO3(a). Sulfite forms in a (2 radical3x2 radical3)R30 degrees structure. The restructuring of the surface atoms during sulfite formation is indicative of the deconstruction of the p(4x4)-O structure. Heating the sulfite-covered surfac…
An effective method, i.e., the solid atom method, is suggested to obtain the Coulomb interaction parameter, U, and the Hund exchange coupling constant, J, for use in the LDA+U calculation. The par~meters are obtained self-consistently during the LDA+U calculation. The method is applied to typical transition metal oxid…
High-energy electrons may be elastically and inelastically scattered by a solid. To a good approximation the effect of inelastic scattering on the elastically scattered electrons may be taken into account using the concept of the complex optical potential. The optical potential may be calculated using electron atomic…
Abstract Low‐molecular‐weight organic acids with one or more carboxylic groups are ubiquitous. In soils, they can originate from leaching of plants, litter decomposition, plant‐roots exudation, and microbial activity. Their presence in the soil may favor the formation of soluble organo‐metallic complexes that improve…
The fairly recent discovery of "quasi-crystals", whose X-ray diffraction patterns reveal certain peculiar features which do not conform with spatial periodicity, has motivated studies of the wave-dynamical implications of "aperiodic order". Within the context of the radiation properties of antenna arrays, an instructi…
Poly(o-anisidine) (POA) coatings were synthesised on low carbon steel substrates by electrochemical polymerisation of o-anisidine under cyclic voltammetric conditions from an aqueous solution of sodium tartrate. The resulting POA coatings were uniform and strongly adherent to the substrates. The coatings were characte…
This paper presents laboratory results of titanium passivated and chromium passivated tinplate specimens lacquered in industrial lines. The lacquered materials were characterised and evaluated in terms of the chemical characteristics of the lacquer; its degree of curing; adhesion; porosity; corrosion resistance in syn…