Resumen Objetivo/contexto: Este artículo analiza el uso de la piedra bezoar americana como objeto polisémico. Mientras que para los amerindios funcionaba como talismán para la caza, los jesuitas, médicos y comerciantes europeos le atribuían propiedades medicinales. Los jesuitas que recogieron las prácticas médicas del Septentrión Novohispano respondieron a la necesidad de atender la salud de los misioneros en tierras remotas. Ejemplo de ello fue el Florilegio Medicinal del padre Juan de Esteyneffer, producto de la adaptación de la flora y la fauna locales. Originalidad: En contraste con los trabajos históricos que se han dedicado a describir y explicar la piedra bezoar como remedio en Europa, este artículo muestra cómo los objetos tienen una trayectoria y se relacionan de diferentes formas con diversos grupos humanos, dependiendo del orden cultural en que se encuentren. En esa lógica, los objetos permiten el cruce de prácticas locales con las de agentes coloniales. Metodología: Esta investigación contrasta información proveniente del trabajo de campo de varios antropólogos, fuentes primarias y trabajos historiográficos. Además, se inscribe en las nuevas propuestas que buscan atribuir vida social a los objetos y, así, dimensionar, sus múltiples circulaciones y significados en espacios interculturales. Conclusiones: La piedra bezoar americana fue un artefacto complejo que tuvo trayectorias y alcances distintos. Para los amerindios, este talismán para la caza era un agente que regulaba las relaciones con la comunidad y lo no humano. En cambio, para los agentes coloniales, por su potencial económico, estaba destinada a transformarse en mercancía farmacéutica, sucedánea de la valiosa piedra bezoar oriental.

Abstract Objective/context: This article analyzes the use of American bezoar stone as a polysemic object. While for Amerindians it worked as a talisman for hunting, European Jesuits, doctors and merchants attributed it medicinal properties. The Jesuits who collected the medical practices of the northern provinces of New Spain responded to the need to take care of the health of missionaries in remote lands. An example of this was the Florilegio Medicinal by Father Juan de Esteyneffer, product of the adaptation of the local flora and fauna. Originality: In contrast to the historical works devoted to describing and explaining bezoar stones as medicine in Europe, this article shows objects as having a trajectory and as relating in different ways to various human groups, depending on the cultural order in which they are found. In this line of reasoning, these objects allow us to compare local practices with those of colonial agents. Methodology: This research contrasts information coming from several anthropologists’s field work, primary sources and historiographical work. In addition, it is part of a new set of proposals that seeks to attribute social life to objects and, thus, to explore their multiple circulations and meanings in intercultural spaces. Conclusions: The American bezoar stone was a complex artifact that had diverse trajectories and scopes. For the Amerindians, this hunting talisman was an agent that regulated relations with the community and nonhuman entities. In contrast, for colonial agents, its economic potential destined it to become a pharmaceutical merchandise, a substitute for the valuable oriental bezoar stone.

Resumo Objetivo/contexto: Este artigo analisa o uso da pedra de benzoar americana como objeto polissêmico. Enquanto para os ameríndios a pedra funcionava como talismã para a caça, os jesuítas, os médicos e os comerciantes europeus atribuíam propriedades medicinais a ela. Os jesuítas que reuniram as práticas médicas na região setentrional da Nova Espanha responderam à necessidade de atender a saúde dos missionários em terras remotas. Um exemplo disso foi o Florilegio Medicinal do padre Juan de Esteyneffer, produto da adaptação da flora e da fauna locais. Originalidade: Em contraste com os trabalhos históricos que se dedicaram a descrever e explicar a pedra de benzoar como remédio na Europa, este artigo mostra como esses objetos têm uma trajetória e se relacionam de diferentes formas com diversos grupos de humanos, dependendo da ordem cultural em que se encontrem. Nessa lógica, os objetos permitem o cruzamento de práticas locais com as de agentes coloniais. Metodologia: Esta pesquisa contrasta informação proveniente do trabalho de campo de vários antropólogos, fontes primárias e trabalhos historiográficos. Além disso, inscreve-se nas novas propostas que buscam atribuir vida social aos objetos e, assim, dimensionar suas múltiplas circulações e significados em espaços interculturais. Conclusões: A pedra de benzoar americana foi um artefato complexo que teve trajetórias e alcances distintos. Para os ameríndios, esse talismã para a caça era um agente que regulava as relações com a comunidade e com o não humano. Por outro lado, para os agentes coloniais, por seu potencial econômico, estava destinada a se transformar em mercadoria farmacêutica, sucedânea da valiosa pedra de benzoar oriental.

Materials degradation due to simultaneous chemical and mechanical effects may occur under a variety of conditions. Galvanized and zinc-iron electrodeposited steels are widely used to protect automobile bodies against corrosion. In such applications, it is important to investigate the electrochemical and tribological behaviour of the coatings, in order to understand the behaviour of those surfaces in a tribological contact exposed to a corrosive environment. In the present paper, the evolution of open circuit potential, for both surfaces, was monitored during reciprocating sliding against an alumina pin in a 3% NaCl solution. The coatings are compared in terms of electrochemical behaviour by polarization tests, open circuit potential and friction coefficient during sliding; and loss of mass after sliding. The surface morphology, after sliding, was examined by SEM. Under the experimental conditions of the present study, the results found in terms of corrosion and wear resistance could be correlated to the differences in morphology, rugosity and composition of the two analysed surfaces.

The development of hybrids materials has been extensively investigated in recent years. The combination of a wide variety of compositions and production processes had permitted the use of these materials in different applications like coatings for corrosion protection of metals. In this work organic-inorganic hybrid materials have been prepared from the hydrolysis of tetraethylorthosilicate and silanol-terminated polidymetilmetoxysilane using a sol-gel process. These materials have been applied on galvanized steel and on steel electroplated with a ZnFe. In order to evaluate the degradation behavior of these coatings, electrochemical techniques (Electrochemical Impedance Spectroscopy and Potentiodynamic Polarization) were used. EIS data was fitted to an equivalent circuit from which the electrochemical parameters were obtained. Results show a good protective character of the hybrid films, when compared with uncovered specimens. The overall performance of the coating systems appears to be highly dependent on the kind of metallic coating applied to the steel.

In the field of biomedical applications a special interest exists regarding the study of the physicochemical and mechanical behaviour of materials, with special focus on the electrochemical degradation of metal/ceramic interfaces. In fact, metal/ceramic interfaces may be present in several biomedical devices, ranging from external or implantable sensors, to dental implants. Diffusion bonding represents an important technique since, in opposition to other production technologies, such as active metal brazing, avoid the possible liberation of certain chemical components harmful to health. The aim of this work is to study the electrochemical degradation of the interface formed between commercially pure Ti and Al2O3 produced by diffusion bonding, in contact with a physiological solution. The present approach included the evaluation of the contribution of individual and pairs of interfacial layers on the global degradation processes. For this propose d.c. electrochemical techniques were used to monitor the open-circuit potential, and to perform potentiodynamic polarization and galvanic corrosion evaluation. Also, electrochemical impedance spectroscopy was used as a complementary technique of the corrosion behaviour of the interface. Chemical composition and morphology of samples and corrosion products were evaluated by SEM and EDS analysis. According to experimental results, two principal reaction layers were formed in the interface: TiAl and Ti3Al. The TiAl layer appears to be the responsible for the strong increase in corrosion rate of the interface.