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The importance of environmental geochemistry baseline in soils of O´Higgins Region, Chile, since it hosts in its eastern area one of the major Cu-Mo producing mines in the country, is to establish and explain relationships between the chemical compositions of the Earth's surface and potential contaminants sources such as mining industry, agriculture and urban activity. A total of 109 samples of urban, peri-urban and rural soils were analyzed with X-ray fluorescence to determine most of the elemental concentrations analyzed. The C and S analyses were performed with the high-temperature combustion method, and a MERCUR mercury analyzer was used for Hg. The study shows that the distribution patterns for most major elements and some trace elements are controlled by the lithologic substrate. This study identified areas with metals and metalloids in high concentrations, which are a risk to the environment and health according to established international regulations. Some of these components correspond to Cu (2500 ppm), Mo (26,5 ppm), As (134,6 ppm), Cr (206.6 ppm), Hg (0.2 ppm), Ni (26.4 ppm), Pb (61.7 ppm), V (227,2 ppm) and Zn (180.3 ppm). Through an elementary association analysis, most of these elements resulted from extractive activities of Cu, metal alloys and oil combustion. It was also possible to trace the use of fertilizers and pesticides in agricultural soils, as well as the combustion of oil related to vehicles in the study area. This information is relevant to implement environmental management strategies to control possible exposure to toxic compounds to human health.

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In this study, we explored the Ti-Nb-Fe system to find an optimal cost-effective composition with the lowest elastic modulus and the lowest added Nb content. Six Ti-(31-4x)Nb-(1+0.5x)Fe ingots were prepared and Nb was substituted with Fe, starting at Ti-31Nb-1.0Fe and going up to Ti-11Nb-3.5Fe (wt%). The ingots were subjected to cold rolling, recrystallization and solution treatment, followed by water-quenching (WQ), furnace cooling (FC) or step-quenching to 350°C, which caused massive formation of isothermal ω phase. All the water-quenched alloys displayed athermal ω phase, which is apparently the result of fully collapsed ß phase. The Fe content improved the compressive strength of the alloys. In the FC alloys, substitution with Fe favored the formation of α phase instead of ω phase, giving rise to a solute-rich ß phase with a lattice parameter of 0.3249nm. Among the FC alloys, the lowest modulus of 83±4GPa was obtained in the Ti-19Nb-2.5Fe alloy, which exhibited fine and well dispersed α precipitation and absence of ω phase. DSC experiments indicated that the experimental alloys showed varying phase stability during heating.

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On the north coast of present-day Peru flourished approximately between 50 and 700 AD, the Moche civilization. It was an advanced culture and the Moche were sophisticated metalsmiths, so that they are considered as the finest producers of jewels and artefacts of the region. The Moche metalworking ability was impressively demonstrated by the objects discovered by Walter Alva and coworkers in 1987, in the excavations of the "Tumbas Reales de Sipán". About 50 metal objects from these excavations, now at the namesake Museum, in Lambayeque, north of Peru, were analyzed with a portable equipment using energy-dispersive X-ray fluorescence. This portable equipment is mainly composed of a small size X-ray tube and a thermoelectrically cooled X-ray detector. Standard samples of gold and silver alloys were employed for quantitative analysis. It was determined that the analyzed artefacts from the "Tumbas Reales de Sipán" are mainly composed of gold, silver and copper alloys, of gilded copper and of tumbaga, the last being a poor gold alloy enriched at the surface by depletion gilding, i.e. removing copper from the surface.

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Hemos estudiado la cinética de transformación isotérmica que ocurre en una aleación comercial AA3003 en el rango de temperaturas comprendido entre 350 °C y 550 °C usando medidas de resistividad eléctrica. El propósito del mismo es dar explicación a la diversidad de valores de energía de activación reportados en la literatura cuando se utiliza la teoría cinética de reacción. La resistividad eléctrica muestra un decrecimiento monótono hasta alcanzar un plateau, siendo tal decrecimiento menor a medida que la temperatura de envejecimiento isotérmica decrece. Para las temperaturas de 350 °C y 550 °C, luego de ligeras variaciones al comienzo del envejecimiento, el comportamiento de la resistividad indica la precipitación de una única fase, mientras que a temperaturas intermedias parecieran coexistir dos fases. En este trabajo logramos demostrar que varios modelos obtenidos de la teoría de reacción nos permiten obtener un rango reducido de la fracción transformada donde los valores de la energía de activación corresponden al proceso de precipitación de fases ricas en Mn.

We have studied the isothermal transformation kinetics of a commercial AA3003 alloy by means of electricalresistivity measurements at temperatures ranging between 350 °C and 550 °C, with the purpose of providing an explanation for the wide array of activation energy values reported in the literature. The electrical resistivity shows a monotonic decrease up to a plateau, this decrease being lower as the aging temperature diminishes. After slight variations at the onset of the aging, the behavior of the resistivity indicates the precipitation of one phase at 350°C and 550°C, while two phases seem to coexist at intermediate temperatures. We show that several reaction theory models permitted us to obtain a reduced range of the transformed fraction where the activation energy values correspond to the process of precipitation of Mn-rich phases.

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Foram comparados os desempenhos das limas endodônticas Flex.R (aço inoxidável) e Onyx.R (NiTi) fabricadas por usinagem, quando submetidas ao ensaio de torçäo à direita e à esquerda. Os resultados obtidos indicaram que o ângulo de torçäo máxima até a fratura foi maior à direita do que à esquerda. Na rotaçäo à direita, estatisticamente näo houve diferença significativa porém, à esquerda, os instrumentos de NiTi apresentaram melhor comportamento. O torque máximo até a fratura näo apresentou diferença significativa entre os instrumentos avaliados. As superfícies de fratura apresentaram características morfológicas como sendo do tipo dúctil

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It is well known that allergic and/or inflammatory reactions can be elicited from the use of gold-coated studs, particularly the type used for piercing ears, since they are left in contact with body fluids until the puncture heals. Inasmuch as gold is known as a non-toxic element, other elements of the substrate material may be responsible for some allergies. Therefore, characteristics of the coating, such as defects that expose the substrate to the human skin or body fluids, play an important role in the development of skin sensitization. In this study, the cytotoxicity of commercial studs used for ear piercing and laboratory-made studs was determined in a culture of mammalian cells. The corrosion performance of the studs was investigated by means of weight loss measurements and electrochemical impedance spectroscopy. The elements that leached out into the medium were also analysed by instrumental neutron activation analysis. Further, the surfaces of the studs were examined by scanning electron microscopy and analysed by energy dispersive spectroscopy to identify defects and reaction products on the surface, both before and after their exposure to the culture medium. The stud which showed lower corrosion performance resulted in higher cytotoxicity. Ti showed no cytotoxicity and high corrosion resistance, proving to be a potential material for the manufacture of ear piercing studs.

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This paper describes two solutions for systematic measurement of surface elevation that can be used for both profile and surface reconstructions for quantitative fractography case studies. The first one is developed under Khoros graphical interface environment. It consists of an adaption of the almost classical area matching algorithm, that is based on cross-correlation operations, to the well-known method of parallax measurements from stereo pairs. A normalization function was created to avoid false cross-correlation peaks, driving to the true window best matching solution at each region analyzed on both stereo projections. Some limitations to the use of scanning electron microscopy and the types of surface patterns are also discussed. The second algorithm is based on a spatial correlation function. This solution is implemented under the NIH Image macro programming, combining a good representation for low contrast regions and many improvements on overall user interface and performance. Its advantages and limitations are also presented.

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Se evaluó visualmente la alteración de color y de brillo de aleaciones de Cu-Al y Cu-Al-Zn, sometiendo las muestras a la acción de diversos medios de inmersión, en función del tiempo. Se observaron también la infuencia de la presencia de una restauración de amalgama adyacente a la prótesis y el comportamiento de la unión soldada.

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