Repassivation of Pits in Aluminum Thin Films

The effect of metal film thickness on repassivation of pits in sputter-deposited Al thin films was investigated in chloride solutions. The repassivation potential and the critical current density, which is the pit current density below which pits stop growing, were determined for pits in Al thin films ranging from 100 Ǻ to 43 μm in thickness. The repassivation potential first decreased as thickness increased from 100 to 4350 Ǻ, and then increased as the film thickness increased further. This behavior was found to be a consequence of the pit current-density/potential relationship. The critical current density, a more informative parameter, decreased for increasing metal film thickness, even when the repassivation potential increased. The critical current density is the minimum current density needed to maintain the critical pit environment and prevent repassivation. The repassivation potential for a given metal film thickness is the potential at which the pit current density drops below the critical value. Mass-transport and ohmic resistance both increase as the metal film thickness increases, but the former enhances pit stability and the latter destabilizes pitting in this system. Pit repassivation, and thus stability, are strongly influenced by mass-transport considerations for pits in very thin pits, even though dissolution at low potentials is not under pure mass-transport control. Ohmic effects become increasingly important as the film thickness increases.J.R.S. was supported by the NASA-Langley Research Center La^2ST Program and the NSF under DMR-9357463

Personal information

Esta sesión de aprendizaje titulada “Personal Information” tiene como objetivo hacer interactuar con sus compañeros y un nativo hablante, mensajes básicos y comunes, donde el aprendizaje comunicativo es fundamental pues se trata de aprender del otro y con el otro, por lo que se requiere cooperación, tolerancia y respeto. Las competencias que usamos como principal guía para la actividad en clase fueron: Expresar ideas, opiniones, emociones y sentimientos sobre acontecimientos sociales para una interacción fluida con un nativo hablante demostrando certeza en su proceso comunicativo. Entiende el mensaje de sus compañeros demostrando sus posiciones en temas de interés. Para el logro de estas competencias se ha tomado en consideración los siguientes indicadores: Identifica la situación comunicativa respondiendo algunas preguntas adivinando el tema de la clase. Identifica el vocabulario relacionado a información personal. Practica hablando y utilizando el vocabulario aprendido. Para el enfoque transversal se designó la educación y valores y como actitud muestra responsabilidad y tolerancia cuando trabaja en pareja. La sesión de aprendizaje ha considerado los momentos didácticos de inicio, proceso y salida. El tema de la sesión fue contextualizado con los saludos y despedidas para motivar el aprendizaje de los estudiantes. Para la evaluación se ha utilizado una ficha de observación con los indicadores propuestos, con una escala de evaluación vigesimal de 0 a 20 y cada indicador con un peso de 0 – 4. También se hicieron preguntas metacognitivas para reflexionar con los estudiantes sobre el proceso de aprendizaje durante la sesión. Finalmente, concluir que los estudiantes lograron saludar y despedir utilizando una correcta pronunciación.This learning session entitled "Personal Information" has to interact with your classmates and a native speaker in basic and common messages, where communicative learning is essential because it is about learning from the other and with the other, so it is required cooperation, tolerance and respect. The competences that we use as the main guide for class activity were: Express ideas, opinions, emotions and feelings about social events for a fluid interaction with a native speaker demonstrating certainty in their communicative process. Understand the message of your colleagues demonstrating their positions on topics of interest. For the achievement of these competences the following indicators have been taken into consideration: Identify the communicative situation by answering some questions by guessing the theme of the class. Identify vocabulary related to personal information. Practice speaking and using the vocabulary learned. For the transversal approach, education and values were designated and as an attitude it shows responsibility and tolerance when working in pairs. The learning session has considered the didactic moments of pre, while and post. The theme of the session was contextualized with greetings and farewells to motivate student learning. For the evaluation, an observation sheet with the proposed indicators has been used, with a vigesimal evaluation scale of 0 to 20 and each indicator with a scale of 0 - 5. Metacognitive questions were also asked to reflect with the students on the process of Learning during the session. Finally, conclude that students managed to greet and say goodbye using correct pronunciation.Trabajo de suficiencia profesiona

Food Bag Program to Address the Immediate Food Needs of Patients During the COVID-19 Crisis

The COVID-19 pandemic has heightened food insecurity across the country. In this report we describe creation of a novel emergency department (ED) food bag program in New York City. The food bag program was designed to help meet immediate food needs of patients being discharged from the ED. Each bag contained shelf-stable food as well as a handout describing other community food resources. The program leveraged community-hospital partnerships, was met with enthusiasm from patients and staff alike, and would be highly replicable to other settings.https://deepblue.lib.umich.edu/bitstream/2027.42/156010/1/FINAL_Food bag program article_complete_7.2.20.pdfDescription of FINAL_Food bag program article_complete_7.2.20.pdf : Main Articl

Corrosion and Passivation of Fe and FeN Films

The role of nitrogen in corrosion and passivation of thin Fe-N films was studied. Sputtered films with different levels of nitrogen were characterized for composition, conductivity, stress, and crystallinity. Corrosion and passivation of the films were evaluated by electrochemical measurements combined with in situ ellipsometry and ex situ x-ray photoelectron spectroscopy. The results indicate that in deaerated solutions the primary action of N is to reduce the catalytic activity of the surface for the hydrogen reaction and thereby reduce corrosion. In aerated solutions the corrosion rate increases with N content. Kinetics of the protective oxide formation as a function of potential, percent N, and the presence of borate buffer are discussed in detail. The work is relevant to the behavior of oxide-free Fe-N surfaces in contact with mild, nearly neutral electrolytes, such as could be used in fabrication of magnetic recording heads

X-Ray Absorption Study of Electrochemically Grown Oxide Films on Al-Cr Sputtered Alloys I. Ex situ Studies

Oxides grown electrochemically in a borate buffer solution on the surface of sputter-deposited AlCr alloy films were studied by x-ray absorption near edge structure (XANES). The measurements were made in air immediately following polarization in solution. The oxides were also examined with x-ray photoelectron spectroscopy (XPS). The effects of alloy composition and thickness as well as applied potential were studied. Cr( VI) was found in the oxides if the applied potential was sufficiently high. The Cr(VI) was enriched at the interface with the electrolyte and the proportion of Cr(VI) in the oxide was higher for alloy films containing more Cr. The Cr(VI) in the oxides could be reversibly reduced to Cr(III) and reoxidized to Cr(VI) by subsequent potentiostatic treatments in solution.Research was carried out in part at the National Synchroton Light Source, Brookhaven National Laboratory, which is supported by the U.S. Department of Energy, Division of Materials Sciences and Division of Chemical Sciences. A. J. D. and H. S. I. were supported by the U.S. Department of Energy, Division of Materials Sciences, Office of Basic Energy Science under Contract No. DE-AC02-76CH00016

Conspecific coprophagy stimulates normal development in a germ-free model invertebrate

Microbial assemblages residing within and on animal gastric tissues contribute to various host beneficial processes that include diet accessibility and nutrient provisioning, and we sought to examine the degree to which intergenerational and community-acquired gut bacteria impact development in a tractable germ-free (GF) invertebrate model system. Coprophagy is a common behavior in cockroaches and termites that provides access to both nutrients and the primary means by which juveniles are inoculated with beneficial gut bacteria. This hypothesis was tested in the American cockroach (Periplaneta americana) by interfering with this means of acquiring gut bacteria, which resulted in GF insects that exhibited prolonged growth rates and gut tissue dysmorphias relative to wild-type (WT) P. americana. Conventionalization of GF P. americana via consumption of frass (feces) from conspecifics and siblings reared under non-sterile conditions resulted in colonization of P. americana gut tissues by a diverse microbial community and a significant (p < 0.05) recovery of WT level growth and hindgut tissue development phenotypes. These data suggest that coprophagy is essential for normal gut tissue and organismal development by introducing beneficial gut bacteria to P. americana, and that the GF P. americana model system is a useful system for examining how gut bacteria impact host outcomes