Materials Literature
按标题、摘要、年份、主题和来源检索公开元数据。结果保留作者、摘要、分类与原始来源链接。
Oxygen diffusion coefficients in pure and doped ZnO polycrystals were determined by means of the gas-solid isotope exchange method using the isotope 18O as oxygen tracer. The diffusion experiments were performed from 900 to 1000 °C, under an oxygen pressure of 10(5) Pa. After the diffusion annealings, the 18O diffusio…
A systematic investigation was undertaken on commercially pure titanium submitted to plasma nitriding. Thirteen different sets of operational parameters (nitriding time, sample temperature and plasma atmosphere) were used. Surface analyses were performed using X-ray diffraction, nuclear reaction and scanning electron…
This paper shows a study about the influence of type and number of sterilizations in the cutting ability of diamond points used in dentistry. As a result, the sterilization using the oven was the process, which didn't result in a decreasing in the cutting ability of the diamond points and, until the second sterilizati…
Hardness of human tooth, both in enamel and dentin, has been measured at different sites using a Vicker's diamond. In this work we show that these values are almost constant all along the enamel and dentin thicknesses. Indentations were done from outer enamel surface to inner dentin layer, going through the enamel-den…
In this work the surface of activated carbon was chemically modified in order to introduce O, S and N containing groups. The activated carbon surface was selectively oxidized with concentrated HNO3 under controlled conditions. Characterization by thermogravimetric analyses, infrared spectroscopy and NaOH titration sug…
A avaliação in vitro da biocompatibilidade de diferentes tipos de biomateriais foi realizada pelo teste de citotoxicidade em cultivo de células de tecido conectivo de camundongos, NCTC Clone 929 da American Type Culture Collection. O estudo comparativo do ensaio de citotoxicidade foi realizado com duas metodologias: 1…
Polypropylene films (PP) surface treated by corona discharge in air was analyzed to verify the changes on surface composition. The presence of oxidized polar groups on the film surface, mainly, C=O, C-O and COH, was confirmed by infrared spectroscopy (FTIR/ATR) and atomic force microscopy (AFM) revealed a dramatic cha…
A selection of materials (stained glasses, lead cames, support elements and putty) from historical stained glass windows of different periods (13th-19th centuries) have been studied. Optical microscopy, scanning electron microscopy, energy dispersive X-ray spectrometry and X-ray diffraction were used as characterizati…
The actual research study, carried out in the Laboratory of Construction Materials of the ETSAM., analyses the modifications in superficial properties (regarding colour and texture) of grey Portland cement mortars due to the use of different formworks release agents (car oil, mineral oil and paraffin) and to the addit…
Zinc self-diffusion coefficients were measured in polycrystalline ZnO of high density (>99% of the theoretical density) and of high purity (> 99.999%). The diffusion experiments were performed from 1006 to 1377 °C, in oxygen atmosphere, for times between 16 and 574 h. The diffusion profiles were established by means o…
The aim of this study was to analyze in vitro surface hardness (micro-indentation tester Wolpert) of different types of amalgam alloys varying the technique and polishing time. Tested were the amalgam: Velvalloy, Permite e Dispersalloy. For each material, 2 polishing techniques were accomplished: T1 (bladed finishing…
Due to its biodegradability, poly(3-hydroxybutyrate) P(3-HB) has attracted much attention in the environmental sector. However, some characteristics of this polymer, such as high crystallinity, poor processability and high brittleness, have lead several research groups to study polymeric blends in order to modify P(3-…
In this work highly dispersed Ru-Sn bimetallic catalysts have been prepared from organobimetallic Cp(PPh3)2Ru-SnX3 (X = Cl or Br) complexes. These single source precursors can be easily impregnated in high surface area supports, such as activated carbon and sol-gel SiO2, and upon controlled thermal treatment the ligan…
The present paper describes the nonohmic behavior of the SnO2.MnO-based system and analyzes the influence of the sintering time and the Nb2O5 concentration on this system's electrical properties. A nonlinear coefficient of ~7 was obtained for a 0.2 mol%-doped Nb2O5 composition, which is comparable to other values repo…
This paper presents the practical application of cm artificial neural network (ANN) to the problem of concrete mix in a factory. After a brief introduction to the complex problem of concrete mixes design and a quick review of the fundamental basis of neurocomputation, an optimal neural network model has been developed…
Zinc oxide, ZnO, is a very interesting compound in science and electronic ceramics technology. ZnO ceramics containing some additives were reported to show varistor action with excellent nonlinearity in current - voltage characteristics. However, investigations were restricted to the ZnO - Bi2O3 ceramic system. Other…