Abstract. In the present work, the corrosion behavior of the as-cast Cu-9Al-3Ag alloy, with shape memory, SMA, and with tempering heat treatments at two temperatures, 400 and 600 °C, were studied. These treatments were selected due to the austenite-martensite phase transition or vice versa. For this investigation, a 0.5 M NaCl electrolyte was used. Micrographs using optical microscopy and scanning electron microscopy show the martensite phase in the Cu-9Al-3Ag alloy, likewise, in the tempered samples the austenite-martensite phases were also observed. For the evaluation of the corrosion behavior, the Tafel model was implemented, for whose curves a potential of ±200 mV was used from the Ecorr. It was observed that the sample with SMA presented a good resistance to corrosion, as well as the tempered samples, unlike the as-cast sample. Finally, impedance tests were carried out using a frequency range of 100 kHz to 10 mHz and an amplitude of 10 mV, in order to observe the resistances to the solution and to the charge transfer present in each one of the samples used.

Resumen. En el presente trabajo se estudió el comportamiento de corrosión en la aleación Cu-9Al-3Ag en estado de colada, con memoria de forma en conjunto con tratamientos térmicos de revenido a temperaturas de 400 y 600 °C. Dichos tratamientos fueron seleccionados debido al cambio de transición de fase austenita-martensita o viceversa. Para esta investigación se utilizó un electrolito a 0.5 M NaCl. Las micrografías mediante microscopia óptica y microscopia electrónica de barrido muestran la fase martensita en la aleación Cu-9Al-3Ag, así mismo, en las muestras revenidas se puede observar las fases austenita-martensita. Para la evaluación del comportamiento de corrosión se implementaron las curvas de Tafel, en las cuales se utilizó un potencial de ±200 mV a partir del Ecorr. Se observó que la muestra con SMA presento una buena resistencia a la corrosión al igual que las muestras revenidas a diferencia de la muestra en estado de colada. Por último, se realizaron pruebas de impedancia utilizando un rango de frecuencia de 100 kHz a 10 mHz y una amplitud de 10 mV, con la finalidad de observar las resistencias a la solución y a la transferencia de carga presentes en cada una de las muestras utilizadas.

Abstract This article aims to present the intercultural experience of Teletandem involving students from two Brazilian federal universities. Following the methodological approach of the experience report (MUSSI; FLORES; ALMEIDA, 2021), we developed a collaborative academic-reflexive essay that emerges from a virtual foreign language practice within the Spanish I course at the Federal University of Campina Grande (UFCG). Inspired by the philosophy of Paulo Freire, we discuss how this tool can foster the teaching and learning of foreign languages, creating authentic interaction scenarios among students and promoting autonomy, reciprocity, and peer collaboration. Simultaneously, we identify some challenges and potential obstacles that may interfere with the activity. We conclude that Teletandem emerges as a powerful intercultural activity capable of fostering exchange and reflection on the demands and challenges faced by rural populations in Latin America.

Resumo Este artigo visa apresentar a experiência intercultural do Teletandem envolvendo estudantes de duas universidades federais brasileiras. Seguindo a abordagem metodológica do relato de experiência (MUSSI; FLORES; ALMEIDA, 2021), elaborou-se de forma colaborativa um ensaio acadêmico-reflexivo que emerge de uma prática virtual de línguas estrangeiras dentro do curso de Espanhol I na Universidade Federal de Campina Grande (UFCG). Inspirados pela filosofia de Paulo Freire, discutimos como essa ferramenta pode fomentar o ensino e a aprendizagem de línguas estrangeiras, criando cenários autênticos de interação entre os/as alunos/as e estimulando a autonomia, a reciprocidade e a colaboração entre pares. Simultaneamente, identificamos alguns desafios e obstáculos potenciais que podem interferir na atividade. Concluímos que o Teletandem se configura como uma poderosa atividade intercultural, capaz de impulsionar a troca e a reflexão sobre as demandas e os desafios dos povos rurais da América Latina.

Resumen: la neuritis óptica es infrecuente como manifestación de sífilis ocular, la falta de características típicas genera retraso en el diagnóstico. Describimos el caso de una mujer de 47 años , inmunocompetente con historia de 4 meses de disminución progresiva de la agudeza visual de predominio izquierdo, asociado a dolor, inyección conjuntival y cefalea, al examen físico con visión de bultos y al fondo de ojo con signos de inflamación ocular dentro de la evaluación diagnostica presenta: VDRL y FTA-ABS positivo en suero, positividad de ANAS y anticuerpos anticardiolipinas igG, LCR con VDRL reactivo, se diagnostica neuritis óptica por neurosifilis en presencia de anticuerpos antifosfolipidos, iniciando tratamiento con penicilina cristalina 24 000 000 de unidades día por 14 días. En pacientes con signos de inflamación ocular debe realizarse VDRL, confirmarse con prueba treponemica, y realizar punción lumbar, el tratamiento precoz se asocia a mejora de desenlaces visuales.

Abstract :optic neuritis is uncommon as an ocular syphilis clinical presentation; the lack of typical features generates delay in the diagnosis. We describe the case of a 47-year-old woman, immunocompetent with a 4-month history of left visual acuity progressive of left side reduction, associated with pain, conjunctival injection and headache, physical examination with lumpy vision and fundus with signs of ocular inflammation, within the diagnostic evaluation, serum VDRL, FTA-ABS was reactive, with ANAS and IgG anticardiolipin antibodies serum positivity, lumbar punction was taken with reactive VDRL, optic neuritis by neurosyphilis was diagnosed, with antiphospholipid antibodies cross reactivity , treatment with crystalline penicillin 24 000 000 of units day for 14 days was started . In patients with signs of ocular inflammation, VDRL should be performed, confirmed with a treponemal test, and a lumbar puncture should be performed. Early treatment is associated with improvement of visual outcomes.

The Chinchilla pluton is a granitic subelipsoidal shaped body that crops out in the central area of the Sierra de Velasco, La Rioja, Argentina, covering an approximate area of 3.75 km². This small body sharply intrudes into Huaco porphyritic granite, or by pegmatoid contacts and in some sectors stockscheider development. Three granite facies were defined based on their textural characteristics, mineral composition and natural radioactitvity. The porphyritic facies presents major areal extent, whereas the equigranular facies and the fine grain boundary facies are poorly represented. All facies have a monzogranitic modal composition. Chemical analysis show high uranium content for all facies, being the equigranular which shows the greatest tenors. This facies is also slightly enriched in alkalis, incompatible elements (F, Rb, Sn and U) and Th/U relations less than 0,8 showing a greater degree of fractionation.

El plutón La Chinchilla es un cuerpo granítico de forma subelipsoidal en planta que aflora en el sector central de la sierra de Velasco, provincia de La Rioja, Argentina, cubriendo un área aproximada de 3,75 km2. Intruye en forma neta al granito porfírico Huaco, o bien mediante contactos pegmatoides y en algunos sectores con desarrollo de stockscheider. Fueron definidas tres facies graníticas en base a sus características texturales, composición mineralógica y radioactividad natural. La facies porfírica de mayor extensión areal, la facies equigranular y la facies de borde de grano fino de escasa representación areal, todas correspondientes modalmente a monzogranitos. Los análisis químicos reflejan contenidos elevados en uranio para todas las facies, siendo la equigranular la que muestra los mayores tenores. Asimismo esta facies se encuentra levemente enriquecida en álcalis, elementos incompatibles (F, Rb, Sn y U) y relaciones Th/U menores a 0,8 evidenciando un mayor grado de fraccionamiento.

A field study of the immune response to the shed acute phase antigen (SAPA) of Trypanosoma cruzi was carried out in the locality of Mizque, Cochabamba department, Bolivia. Schoolchildren (266), with an average of 8.6 ± 3.6 years, were surveyed for parasitological and serological diagnosis, as well as antibodies directed against SAPA using the corresponding recombinant protein in ELISA. The antibodies against SAPA were shown in 82% of patients presenting positive serological diagnosis (IgG specific antibodies). The positive and negative predictive values were 0.88. Antibodies anti-SAPA were shown in 80.8% of the chagasic patients in the initial stage of the infection (positive IgM serology and/or positive buffy coat (BC) test) and in 81.4% of the patients in the indeterminate stage of the infection (positive IgG serology with negative BC and IgM tests). These results show that the anti-SAPA response is not only present during the initial stage of the infection (few months) but extends some years after infection