Materials Literature
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Very low molecular weight polydimethylsiloxane (PDMS) has been synthesized and characterized by using Infrared spectroscopy (IR), nuclear magnetic resonance, thermogravimetric analysis (TGA) and differential scanning calorimetry. Molecular weight distribution of PDMS has been determined by using multiple angle light s…
Abstract Pinking of TiO 2 ‐pigmented PVC can be observed for profiles exposed to the mild environmental conditions of northern European countries. In a previous paper, the pinking phenomenon was accounted for at the molecular level by the formation of polyene sequences, which are not completely photooxidatively bleach…
The feasibility of constructing a tissue-engineered heart valve on an acellular porcine aortic valve leaflet was evaluated. A detergent and enzymatic extraction process was developed to remove the cellular components from porcine aortic valves. The acellular valve leaflets were seeded for 7 days in vitro with cells fr…
Subsolidus phase equilibria in the system Fe 2 O 3 –Al 2 O 3 –TiO 2 were investigated between 1000° and 1300°C. Quenched samples were examined using powder X‐ray diffraction and electron probe microanalytical methods. The main features of the phase relations were: (a) the presence of an M 3 O 5 solid solution series b…
Abstract Raman spectroscopy was applied to investigate changes in the hydration state of chemically modified porcine pericardium tissue. Chemically modified tissues are used in construction of bioprostheses for replacement surgery including dermis, heart valves and blood vessels. The hydration state is a very importan…
As borrachas, para serem convertidas em materiais úteis do ponto de vista de aplicações, precisam ser misturadas a alguns ingredientes, os quais vão lhes dar as características desejadas para, então, serem vulcanizadas. Neste artigo, os aspectos históricos da vulcanização são abordados bem como a evolução dos aditivos…
Abstract In this paper we dealt with the problem of wetting and ascending of a liquid along a fiber bundle. Two issues are first addressed including the criterion for complete wetting of the fiber bundle and the ascension liquid profile on a partially dipped vertical fiber bundle. Both topics are studied theoretically…
Neste trabalho foram estudadas as propriedades micro e macroscópicas de misturas físicas binárias de poliamida 6 [PA6] com copolímero poli(etileno-co-propileno-co-dieno) [EPDM] e em presença de pequenas quantidades de EPDM ou EPM enxertados com anidrido maleico, atuando como agentes compatibilizantes. Os componentes p…
To constrain the effect of composition and temperature on the elasticity of glasses and super‐cooled liquids, acoustic velocities of samples in the pseudoternary system anorthite‐diopside‐forsterite (An‐Di‐Fo) were measured by Brillouin spectroscopy. Both the longitudinal and shear wave velocities were measured in the…
Abstract Using the generalized dual method, closed analytical expressions for the coordinates of quasiperiodic lattices, derived from periodic or quasiperiodic grids, are given. The obtained formulae constitute a useful and practical tool to generate and perform calculations in quasi periodic structures.
We investigate the electronic characteristics and the absorption spectra of poly(3-octylthiophene), POT, films grown by electrochemical methods onto Au substrates. We discuss the results considering the morphological factor. POT films thickness can be controlled by current density in the electropolymerization process.…
The microstructures of as-cast and slowly solidified Al-Cu-Fe ternary alloys in the vicinity of the icosahedral phase region have been investigated using light microscopy and scanning electron microscopy. The chemical composition of the different phases present has been determined by energy-dispersive X-ray spectrosco…
A cosmetic patch containing tamarind fruit extract was formulated and developed by blending two types of natural polymers: chitosan with molecular weight of 100 000 and starch such as corn, potato or tapioca starch. The physicochemical characteristics, i.e. flexibility, colour, transparency, integrity, gloss, water so…
A solution to the equation of grain-boundary diffusion is obtained under conditions where migration of the diffusant from the boundaries into the grains is absent and the diffusion coefficient decreases with time from an increased value to a value characteristic of equilibrium grain boundaries. The specific features o…
The displacement cross-section of iron was calculated for gamma-ray irradiation with the energy range of 1 to 15 MeV, which corresponds to radiation fields in fission reactors. Three gamma-material interactions, Compton scattering, pair production and photoelectric effect were considered. The displacements induced by…
The inhibitive action of triazoles and surfactants on the corrosion of carbon steel has been studied using the weight loss method and electrochemical studies. Results obtained show that these organic compounds are very good inhibitors. Potentiodynamic polarisation studies clearly reveal the type of inhibitor. The corr…
Abstract [DodMe 2 S] 2 AgI 3 and [DodMe 2 S]Ag 2 I 3 were obtained from mixtures of dodecyldimethylsulfonium iodide and silver iodide in acetonitrile solution. [DodMe 2 S] 2 AgI 3 crystallizes in the orthorhombic crystal system, space group Pbca and contains trigonal planar anions AgI 3 2− , while [DodMe 2 S]Ag 2 I 3…
Abstract Two biphenyl lignans, α ‐ and β ‐DDB ( 1 and 2 , respectively) were efficiently synthesized without contamination by other regio‐isomers. The different yields of the Ullmann coupling reactions for the synthesis of 1 and 2 were rationalized by calculating steric hindrance, stability, entropy change, and heat‐o…
The inhibition efficiency (IE) of various concentrations of a caffeine-Zn2+ system in controlling corrosion of mild steel immersed in an aqueous solution containing 60 ppm of Cl– was evaluated by a weight-loss study. The formulation consisting of 50 ppm of caffeine and 50 ppm of Zn2+ showed 91% IE. A synergistic effec…
In this work, the frequency relaxation of the dielectric permittivity of BaBi 2 Ta 2 O 9 (BBT) and BaBi 2 Nb 2 O 9 (BBN) ceramics is investigated in the wide temperature range. Both compositions feature behavior typical for relaxor ferroelectrics including the strong frequency dispersion of the permittivity, the prono…