Ruido magnético de barkhausen: ensayo no destructivo para la evaluación de grados de dureza en aceros

En el presente trabajo es presentada la aplicación de la técnica de medición del Ruido Magnético de Barkhausen (RMB) en la caracterización del perfil de dureza producido en un ensayo Jominy. Los efectos de las alteraciones en el material (AISI 4140 y AISI 5160), producidos por este ensayo han sido observados en las mediciones de RMB, encontrándose una buena correlación entre el valor inverso del parámetro RMBrms y las medidas de dureza Vickers realizadas. Los resultados presentados evidencian la viabilidad de la utilización de la técnica de medición del RMB como ensayo no destructivo en la identificación de diferentes niveles de dureza de materiales ferromagnético

Influencia del temple y revenido del acero inoxidable martensítico aisi-sae 420 en las señales de ruido magnético de barkhausen

RESUMEN: Los aceros inoxidables martensíticos responden a tratamientos térmicos de recocido, temple y revenido, modificando su microestructura, la cual se caracteriza normalmente por métodos convencionales de caracterización microestructural, sin embargo no se han reportado ensayos no destructivos para el monitoreo de los tratamientos térmicos. El ruido magnético de Barkhausen se ha explorado como una técnica no destructiva para evaluación microestructural y por tanto, se presentan en este trabajo resultados de análisis de Ruido Magnético de Barkhausen para evaluar modificaciones microestructurales en un acero AISI 420. Se realizaron temples a 1020°C y 1050°C en dos medios de enfriamiento, aire y aceite, con un posterior revenido a 100°C durante dos horas, con el fin comparar los cambios en el estado microestructural. Las muestras fueron evaluadas por microscopía electrónica de barrido (MEB), microscopía óptica (MO) y ensayos de dureza Vickers, además se hicieron mediciones de la señal del Ruido Magnético de Barkhausen (RMB). Se encontró que existe una correlación entre los valores de durezas, las variaciones microestructurales y los valores rms (root mean square) de las señales de Ruido Magnético de Barkhausen.ABSTRACT: The martensitic stainless steels response to annealing, hardening and tempering heat-treating changing the microstructure, which is usually characterized by conventionally methods of microstructural characterization. However, there are not reports about nondestructive testing by monitoring of microstructural changes for heat-treating. The Magnetic Barkhausen Noise (MBN) has been explored by a nondestructive testing for microstructural changes. In this work, it is used the Magnetic Barkhausen Noise to assess microstructural changes in a martensitic stainless steel AISI-SAE 420, subjected to hardening heat treatment at 1020°C with air and oil cooling and subsequent tempering at temperatures of 100°C, for two hours. Microstructural characterization was performed using Scanning Electron Microscopy (SEM), Optical Microscopy (OM) and Vickers hardness tests (HV). It was found a relation between the microstructures by the different heat treating and rms (root mean square) values of the Barkhausen signals

Common evolutionary origin of acoustic communication in choanate vertebrates

Acoustic communication, broadly distributed along the vertebrate phylogeny, plays a fundamental role in parental care, mate attraction and various other behaviours. Despite its importance, comparatively less is known about the evolutionary roots of acoustic communication. Phylogenetic comparative analyses can provide insights into the deep time evolutionary origin of acoustic communication, but they are often plagued by missing data from key species. Here we present evidence for 53 species of four major clades (turtles, tuatara, caecilian and lungfish) in the form of vocal recordings and contextual behavioural information accompanying sound production. This and a broad literature-based dataset evidence acoustic abilities in several groups previously considered non-vocal. Critically, phylogenetic analyses encompassing 1800 species of choanate vertebrates reconstructs acoustic communication as a homologous trait, and suggests that it is at least as old as the last common ancestor of all choanate vertebrates, that lived approx. 407 million years before present

Relation between magnetic Barkhausen noise and hardness for jominy quench tests in SAE 4140 and 6150 steels

he nondestructive Magnetic Barkhausen Noise (MBN) technique was applied for the evaluation of SAE 4140 and SAE 6150 steels after a Jominy end-quench test. Microstructures were also characterized by SEM (Scanning Electron Microscope) and hardness tests. MBN measurements were performed on the same sample regions at three excitation frequencies. Different parameters of the measured signals (signal peak position and height, and Root mean square) were calculated. A relationship between mechanical hardness and MBN parameters was found for both materials, with the best correlation coefficient being found in low excitation frequency range.The authors would like to thank the State of São Paulo Research Foundation, FAPESP (Process 05/57146-0). M.F. de Campos and L.R. Padovese thank CNPq. We thank Dr. Martin Sab- lik for the critical reading of the manuscrip

Common evolutionary origin of acoustic communication in choanate vertebrates

Acoustic communication, broadly distributed along the vertebrate phylogeny, plays a fundamental role in parental care, mate attraction and various other behaviours. Despite its importance, comparatively less is known about the evolutionary roots of acoustic communication. Phylogenetic comparative analyses can provide insights into the deep time evolutionary origin of acoustic communication, but they are often plagued by missing data from key species. Here we present evidence for 53 species of four major clades (turtles, tuatara, caecilian and lungfish) in the form of vocal recordings and contextual behavioural information accompanying sound production. This and a broad literature-based dataset evidence acoustic abilities in several groups previously considered non-vocal. Critically, phylogenetic analyses encompassing 1800 species of choanate vertebrates reconstructs acoustic communication as a homologous trait, and suggests that it is at least as old as the last common ancestor of all choanate vertebrates, that lived approx. 407 million years before present

Oleate but not stearate induces the regulatory phenotype of myeloid suppressor cells

Tumor infiltrating myeloid cells play contradictory roles in the tumor development. Dendritic cells and classical activated macrophages support anti- tumor immune activity via antigen presentation and induction of pro- inflammatory immune responses. Myeloid suppressor cells (MSCs), for instance myeloid derived suppressor cells (MDSCs) or tumor associated macrophages play a critical role in tumor growth. Here, treatment with sodium oleate, an unsaturated fatty acid, induced a regulatory phenotype in the myeloid suppressor cell line MSC-2 and resulted in an increased suppression of activated T cells, paralleled by increased intracellular lipid droplets formation. Furthermore, sodium oleate potentiated nitric oxide (NO) production in MSC-2, thereby increasing their suppressive capacity. In primary polarized bone marrow cells, sodium oleate (C18:1) and linoleate (C18:2), but not stearate (C18:0) were identified as potent FFA to induce a regulatory phenotype. This effect was abrogated in MSC-2 as well as primary cells by specific inhibition of droplets formation while the inhibition of de novo FFA synthesis proved ineffective, suggesting a critical role for exogenous FFA in the functional induction of MSCs. Taken together our data introduce a new unsaturated fatty acid-dependent pathway shaping the functional phenotype of MSCs, facilitating the tumor escape from the immune system

High levels of T lymphocyte activation in Leishmania-HIV-1 co-infected individuals despite low HIV viral load

<p>Abstract</p> <p>Background</p> <p>Concomitant infections may influence HIV progression by causing chronic activation leading to decline in T-cell function. In the Americas, visceral (AVL) and tegumentary leishmaniasis (ATL) have emerged as important opportunistic infections in HIV-AIDS patients and both of those diseases have been implicated as potentially important co-factors in disease progression. We investigated whether leishmaniasis increases lymphocyte activation in HIV-1 co-infected patients. This might contribute to impaired cellular immune function.</p> <p>Methods</p> <p>To address this issue we analyzed CD4⁺T absolute counts and the proportion of CD8⁺T cells expressing CD38 in <it>Leishmania</it>/HIV co-infected patients that recovered after anti-leishmanial therapy.</p> <p>Results</p> <p>We found that, despite clinical remission of leishmaniasis, AVL co-infected patients presented a more severe immunossupression as suggested by CD4⁺T cell counts under 200 cells/mm³, differing from ATL/HIV-AIDS cases that tends to show higher lymphocytes levels (over 350 cells/mm³). Furthermore, five out of nine, AVL/HIV-AIDS presented low CD4⁺T cell counts in spite of low or undetectable viral load. Expression of CD38 on CD8⁺T lymphocytes was significantly higher in AVL or ATL/HIV-AIDS cases compared to HIV/AIDS patients without leishmaniasis or healthy subjects.</p> <p>Conclusions</p> <p><it>Leishmania </it>infection can increase the degree of immune system activation in individuals concomitantly infected with HIV. In addition, AVL/HIV-AIDS patients can present low CD4⁺T cell counts and higher proportion of activated T lymphocytes even when HIV viral load is suppressed under HAART. This fact can cause a misinterpretation of these laboratorial markers in co-infected patients.</p

Developing and validating a clinical algorithm for the diagnosis of podoconiosis

Background Difficulties in reliably diagnosing podoconiosis have severely limited the scale-up and uptake of the World Health Organization–recommended morbidity management and disability prevention interventions for affected people. We aimed to identify a set of clinical features that, combined into an algorithm, allow for diagnosis of podoconiosis. Methods We identified 372 people with lymphoedema and administered a structured questionnaire on signs and symptoms associated with podoconiosis and other potential causes of lymphoedema in northern Ethiopia. All individuals were tested for Wuchereria bancrofti–specific immunoglobulin G4 in the field using Wb123. Results Based on expert diagnosis, 344 (92.5%) of the 372 participants had podoconiosis. The rest had lymphoedema due to other aetiologies. The best-performing set of symptoms and signs was the presence of moss on the lower legs and a family history of leg swelling, plus the absence of current or previous leprosy, plus the absence of swelling in the groin, plus the absence of chronic illness (such as diabetes mellitus or heart or kidney diseases). The overall sensitivity of the algorithm was 91% (95% confidence interval [CI] 87.6 to 94.4) and specificity was 95% (95% CI 85.45 to 100). Conclusions We developed a clinical algorithm of clinical history and physical examination that could be used in areas suspected or endemic for podoconiosis. Use of this algorithm should enable earlier identification of podoconiosis cases and scale-up of interventions

Valico di Valbona: the mollusc assemblage in the marls of the Rotzo Member.

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