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Over 30 white and coloured titanium enamels of different origin were tested with a derivatograph. Thermoceram crucibles were used, which enabled the tests to be interrupted when a change was indicated by the DTA curve. The crucible was removed from the derivatograph, and the sample pulverized and studied by X-ray diffraction method. A major difference compared to previous observations was the fact that the exothermic peak indicating the anatase-rutile transformation was also found on the DTA curves of certain anatase-type enamels. With these enamels the temperature relating to the start of the transformation peak was regarded as the critical temperature, as at a temperature below this the enamel was stable, but above it unstable.

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. Gee-Clough and A. I. Mufti (1989) Performance Evaluation of an Enamel-Coated Mouldboard Plough. Agricultural Engineering Vol. 3, pp. 1633–1638, Land and Water Use, Dodd & Grace (eds.), Balkema, Rotterdam

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Central European Geology
Authors:
Gabriella Ilona Kiss
,
Péter Szabó
,
Marianna Túri
,
István Futó
,
János Kovács
, and
László Palcsu

composition of the oxygen-bearing materials (e.g., enamel from teeth) and isotopic composition of the environmental water as well as local temperature, the oxygen isotopic investigation of terrestrial mammal fossils can contribute to an understanding of the

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Summary

This communication is concerned with the general circumstances under which the corona graeca of the Holy Crown of Hungary would have been produced in Constantinople. It is first considered in the context of „diplomatic gifts”, and is compared with other enamels of the same period that are now in Tbilisi, although it is usually agreed that these are of lower artistic standard than those in Budapest. The point is made that the crown must be the result of the same technical restrictions as any other examples of Byzantine enamel, and that this aspect of production could have involved the re-use of individual plaques, such as that with a rounded top portraying Michael VII Doukas. The question of the locality in the city where the workshop in which the crown was made is discussed, and the minimal evidence for the existence of a „palace workshop”is noted. It is suggested that the modest value of the gems in the crown could be the result of diplomatic or economic considerations; for modern eyes the contrast between them and the perfection of the enamels demands some explanation of this kind. It is pointed out that all the evidence points to there never having been any enamels used in the crowns worn by Byzantine emperors.

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Summary

This article attempts to provide contexts for the three types of enamel on the Holy Crown of Hungary. The enamels on the corona graeca, which are securely dated by their inclusion of a portrait of the Hungarian king Géza I (1074–1077), occupy a mid-point in the development of technically similar Byzantine enamels. By reference to both Byzantine and western medieval practice, the enamels on the corona latina are established as twelfth-century productions. Finally, the akroterioi, or ‘pinnae’, the triangular and semicircular projections attached to the upper edge of the corona graeca, are placed in a long but little-recognized tradition of technical virtuosity.

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Abstract  

Using electron spin resonance (ESR), tooth enamel is a possible dosimeter in case of a radiation accident. To check the present status of this technique, we conducted a local intercomparison study. We irradiated several samples of tooth enamel with a60Co source. Three institutes in Belgium and The Netherlands recorded the ESR signal of the samples. The results of the measurements and the methods used are compared. It is concluded that ESR on tooth enamel can be a useful technique in accident dosimetry, provided further research is done.

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Abstract  

A radiometric method was applied to assess enamel wear by another enameland by restorative materials. The radioactive enamel was submitted to wearin a machine which allows sliding motion of an antagonistic surface in contactwith the radioactive enamel. The enamel wear was evaluated by measuring thebeta-activity of 32P transferred to water from this irradiatedtooth. Results obtained indicated that dental porcelains cause pronouncedenamel wear when compared with that provoked by another natural enamel orby resin materials. Resin materials caused less enamel wear than another naturalenamel. Vickers microhardness data obtained for antagonistic materials showeda correlation with the wear caused to the enamel.

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Abstract  

Particle induced X-ray emission analysis (PIXE) and nuclear reaction analysis have been applied to multielemental analysis of human dental enamel in a proton microprobe. The PIXE technique was excercised for the characterization of multielemental lateral distributions on and just below the sample surface. For the assessment of depth distributions of fluorine the resonant nuclear reaction19F(p,aλ)16O was used. The combination of two analytical techniques comprising both atomic and nuclear interactions in a microprobe was applied to enamel samples of different origins. One sample constituted a healthy enamel and the other one enamel from a restored tooth. The microprobe in the combined mode was demonstrated to permit the establishment of lateral, concentration gradients of elements heavier than phosphorus with a resolution of 15 μm in enamel and simultaneously of depth distributions of fluorine better than 0.7 μm. The detection limits approached, 10–25 ppm for most of the elements considered.

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Abstract  

The remineralization effect of fluoride has been measured by surface microhardness on tooth enamel. The purpose of this study was to investigate the relationship between microhardness and fluorine concentration on tooth enamel. Twelve sound bovine enamel specimens were prepared and immersed in 0.05% NaF solution for 1, 3, 6, 24 and 36 hours, respectively. The concentration of fluorine in specimens were measured by PIGE analysis and surface microhardness of each specimen was measured by surface microhardness tester. Fluorine concentration was increased by immersing time. There was no change in microhardness of each specimen by fluorine content. The results of this study suggest that there was no relationship between the fluorine concentration and surface microhardness in sound tooth enamel. PIGE analysis can be used effectively to assess the remineralization effect of fluorine content in tooth enamel.

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Abstract  

Thermoanalytical investigations TGA/DTG/DSC of polyamide–imide enamel after thermal ageing have been presented. The lifetimes at 260, 270, 280, 290, 300 °C were determined. The thermograms of the enamels after attaining of their lifetimes much depend on the ageing temperature. The temperatures of 5% loss of mass that much increase after thermal ageing appear the most sensitive indicator of ageing rate. The residue of mass at 800 °C increases after ageing, even to 27%, due to diffusion of copper ions from the conductor into enamel during annealing. The copper contents in aged coatings could be also an indicator of ageing rate.

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