High Temperature Oxidation Behavior of Nb-20Mo-15Si-5B-20Cr Alloy

Materials for high temperature applications, such as jet engines, gas turbines and turbine blades, require a balanced combination of physical and chemical properties to withstand the aggressive environments in which they are utilized. Some of the properties required are high strength, low density, high melting point and good oxidation resistance at elevated temperatures [1-3]. For this reason, the microstructure and oxidation behavior of the Nb-20Mo-15Si-5B-20Cr alloy (at.%) has been studied as a potential candidate to replace Nickel-based alloys currently used in the aerospace industry. Short term oxidation (STO) and long term oxidation (LTO) studies have been performed in air for this alloy over a temperature range from 700°C to 1400°C, for 24 and 168 hours respectively. Oxidation curves for this alloy were obtained by plotting the mass gain per unit area as a function of temperature and time to determine its oxidation resistance. Microstructure of the alloy and oxidized products were characterized using x-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). According to results, the microstructure is composed of BCC solid solution (α), tetragonal Nb5Si3, Nb3Si, hexagonal Laves phase NbCr2 and eutectic like microconstituent α, Nb3Si and NbCr2. The oxidation products at 700 to 1300°C show the presence of Nb2O5, SiO2, CrNbO4, among others. The parabolic and linear oxidation rate constants values indicate that the studied alloy is competitive when compared to the values for Nb-based alloys reported by different authors

High temperature oxidation behavior of niobium-molybdenum-silicon-boron-chromium alloy

Materials for high temperature applications, such as jet engines, gas turbines and turbine blades, require a balanced combination of physical and chemical properties to withstand the aggressive environments in which they are utilized. Some of the properties required are high strength, low density, high melting point and good oxidation resistance at elevated temperatures [1-3]. For this reason, the microstructure and oxidation behavior of the Nb-20Mo-15Si-5B-20Cr alloy (at. %) has been studied as a potential candidate to replace nickel-based alloys currently used in the aerospace industry. Short term oxidation (STO) and long term oxidation (LTO) studies have been performed in air for this alloy over a temperature range from 700°C to 1400°C, for 24 and 168 hours respectively. Oxidation curves for this alloy were obtained by plotting the mass gain per unit area as a function of temperature and time to determine its oxidation resistance. STO was temperature dependent and oxidation curve shows a minimum mass gain per unit area between 900 and 1000°C. LTO was time dependent and curves show a minimum mass gain at 1200 and 1300°C. Parabolic behavior was observed at those temperatures. Microstructure of the alloy and oxidized products were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). According to results, the microstructure is composed of body center cubic (BCC) solid solution (α), tetragonal Nb 5Si3, Nb3Si, hexagonal Laves phase NbCr2 and a eutectic like microconstituent α, Nb3Si and NbCr2. The oxidation products vi at 700 to 1300°C show the presence of Nb2O5, SiO2, CrNbO4, among others. The parabolic and linear oxidation rate constants values indicate that the studied alloy is competitive when compared to the values for Nb-based alloys reported by different authors

Sobrepeso e ingesta alimentaria en escolares de la zona Costa del Estado de Oaxaca

Introduction: Overweight and obesity are a public health concern with particular importance in childhood, since in this day, habits are established that condition food intake. Mexico occupies the first place in childhood obesity, in Oaxaca the jurisdictions with the highest index are la Costa, Tuxtepec, and el Istmo. The city of Puerto Escondido of Oaxaca coast, has social and cultural characteristics that place it in a context vulnerable. Objective: To describe the prevalence of overweight, obesity and food intake in children from 9 to 13 years old in an urban elementary school in the city of Puerto Escondido. Methodology: Descriptive study-transversal with population of 203 students from 9 to 13 years old. The procedure included a sample of 133 students to whom a personal data card was applied, a questionnaire on food intake and anthropometric measurements for the calculation of body mass index (BMI). Results: 50.4% of the students were boys and 49.6% were girls. In respect to the BMI for age, more than 50% had a weight above normal: 32.33% with overweight and 22.56% with obesity. 75.19% of students have a normal overeating, which indicates that they are at the limit between maintaining a healthy body weight. Conclusion: The prevalence of overweight and obesity continues to increase and is marked as age increases; the psychological factors have an important impact on the dietary intake of students.Introducción: El sobrepeso y la obesidad son un problema de salud pública en la niñez, dado que en esta época se establecen hábitos que condicionan la ingesta alimentaria. México ocupa el primer lugar a nivel mundial en obesidad infantil; en Oaxaca las jurisdicciones con mayor índice son la Costa, Tuxtepec y el Istmo. La ciudad de Puerto Escondido de la región Costa de Oaxaca, posee características sociales y culturales que la sitúan en un contexto vulnerable. Objetivo: Describir la prevalencia de sobrepeso, obesidad e ingesta alimentaria en niños y niñas de 9 a 13 años de una escuela primaria urbana de la Ciudad de Puerto Escondido. Metodología: Estudio descriptivo-transversal con una población de 203 escolares de 9 a 13 años. El procedimiento incluyó una muestra de 133 escolares a los que se aplicaron una Cédula de Datos Personales, Cuestionario de Sobreingesta Alimentaria y medidas antropométricas para el calculó de Índice de Masa Corporal (IMC). Resultados: El 50.4% de los escolares fueron niños y 49.6% niñas. Respecto al IMC para la edad, más del 50% presentaron un peso por arriba de lo normal: 32.33% con sobrepeso y 22.56% con obesidad. El 75.19% de los escolares tiene una sobreingesta normal, lo que indica que se encuentran en el límite entre conservar un peso corporal sano. Conclusión: La prevalencia de sobrepeso y obesidad continúa en incremento y es marcada conforme aumenta la edad; los factores psicológicos repercuten de forma importante en la ingesta alimentaria de los escolares

Sobrepeso e ingesta alimentaria en escolares de la zona Costa del Estado de Oaxaca

Introducción: El sobrepeso y la obesidad son un problema de salud pública en la niñez, dado que en esta época se establecen hábitos que condicionan la ingesta alimentaria. México ocupa el primer lugar a nivel mundial en obesidad infantil; en Oaxaca las jurisdicciones con mayor índice son la Costa, Tuxtepec y el Istmo. La ciudad de Puerto Escondido de la región Costa de Oaxaca, posee características sociales y culturales que la sitúan en un contexto vulnerable. Objetivo: Describir la prevalencia de sobrepeso, obesidad e ingesta alimentaria en niños y niñas de 9 a 13 años de una escuela primaria urbana de la Ciudad de Puerto Escondido. Metodología: Estudio descriptivo-transversal con una población de 203 escolares de 9 a 13 años. El procedimiento incluyó una muestra de 133 escolares a los que se aplicaron una Cédula de Datos Personales, Cuestionario de Sobreingesta Alimentaria y medidas antropométricas para el calculó de Índice de Masa Corporal (IMC). Resultados: El 50.4% de los escolares fueron niños y 49.6% niñas. Respecto al IMC para la edad, más del 50% presentaron un peso por arriba de lo normal: 32.33% con sobrepeso y 22.56% con obesidad. El 75.19% de los escolares tiene una sobreingesta normal, lo que indica que se encuentran en el límite entre conservar un peso corporal sano. Conclusión: La prevalencia de sobrepeso y obesidad continúa en incremento y es marcada conforme aumenta la edad; los factores psicológicos repercuten de forma importante en la ingesta alimentaria de los escolares.   Abstract Introduction: Overweight and obesity are a public health concern with particular importance in childhood, since in this day, habits are established that condition food intake. Mexico occupies the first place in childhood obesity, in Oaxaca the jurisdictions with the highest index are la Costa, Tuxtepec, and el Istmo. The city of Puerto Escondido of Oaxaca coast, has social and cultural characteristics that place it in a context vulnerable. Objective: To describe the prevalence of overweight, obesity and food intake in children from 9 to 13 years old in an urban elementary school in the city of Puerto Escondido. Methodology: Descriptive study-transversal with population of 203 students from 9 to 13 years old. The procedure included a sample of 133 students to whom a personal data card was applied, a questionnaire on food intake and anthropometric measurements for the calculation of body mass index (BMI). Results: 50.4% of the students were boys and 49.6% were girls. In respect to the BMI for age, more than 50% had a weight above normal: 32.33% with overweight and 22.56% with obesity. 75.19% of students have a normal overeating, which indicates that they are at the limit between maintaining a healthy body weight. Conclusion: The prevalence of overweight and obesity continues to increase and is marked as age increases; the psychological factors have an important impact on the dietary intake of students

Curcumin Provides Hepatoprotection against Amoebic Liver Abscess Induced by Entamoeba histolytica in Hamster: Involvement of Nrf2/HO-1 and NF-κB/IL-1β Signaling Pathways

Amoebic liver abscess (ALA) is the most common extraintestinal amoebiasis caused by Entamoeba histolytica (E. histolytica). However, despite current knowledge and scientific advances about this infection, there are no effective treatments to prevent it. Herein, the antiamoebic capacity of curcumin in a hamster model was evaluated. Curcumin (150 mg/kg, p.o., daily during 10 days before infection) considerably prevents liver damage induced at 12 and 48 h post-intrahepatic inoculation of trophozoites and decreases ALT, ALP, and γ-GTP activities, and macroscopic and microscopic observations were consistent with these results. On the other hand, after one week of intraportal inoculation, liver damage was prevented by curcumin (150 mg/kg, p.o., daily, 20 days before amoebic inoculation and during the week of infection); liver/body weight ratios and tissue and histological stains showed normal appearance; in addition, the increases in ALT, ALP, and γ-GTP activities were prevented; the depletion of glycogen content induced by the amoebic damage was partially but significantly prevented, while NF-κB activity was inhibited and the expression of IL-1β was reduced; Nrf2 production showed a tendency to increase it, and HO-1 protein was overexpressed. These results suggest for the first time that curcumin can be a compound with antiamoebic effect in the liver, suggesting that its daily use could help greatly decrease the incidence of this type of infection

Adrenergic regulation during acute hepatic infection with Entamoeba histolytica in the hamster: involvement of oxidative stress, Nrf2 and NF-KappaB

Oxidative stress and transcriptional pathways of nuclear factor erythroid 2-related factor 2 (Nrf2) and nuclear factor kappa-B (NF-κB) are critically involved in the etiopathology of amebic liver abscess (ALA). In this work, we studied the relationship between the adrenergic nervous system and ALA in the hamster. ALA was visible at 12 h of infection. While 6-hydroxidopamine (6-OHDA) decreased infection, propranolol (β-adrenergic blocker) treatment was associated with less extensive liver damage, and phentolamine treatment (α-adrenergic blocker) significantly reduced ALA compared to 6-OHDA and propranolol. Serum enzymatic activities of alanine aminotransferase (ALT) and γ-glutamyl transpeptidase (γ-GTP) were increased at 12 h post-infection. Chemical denervation and α and β-adrenergic blockers decreased ALT to normal levels, while 6-OHDA and propranolol showed a trend to decrease γ-GTP but phentolamine significantly reduced γ-GTP. Amebic infection increased oxidized glutathione (GSSG) and decreased both reduced glutathione (GSH) and the GSH/GSSG ratio. Propranolol and 6-OHDA showed a tendency to decrease GSSG. However, GSH, GSSG and GSH/GSSG returned to normal levels with phentolamine. Furthermore, amebic infection increased pNF-κB and interleukin-1β (IL-1β), and showed a tendency to decrease hemoxigenase-1 (HO-1), but not Nrf2. Chemical denervation showed a trend to decrease pNF-κB and IL-1β, and neither Nrf2 nor HO-1 increased significantly. In addition, NF-κB and IL-1β were attenuated by propranolol and phentolamine treatments, although phentolamine showed significant overexpression of Nrf2 and HO-1. This suggests that the adrenergic system may be involved in oxidative stress and in modulation of the Nrf2 and NF-κB pathways during ALA development

Adrenergic regulation during acute hepatic infection with

Oxidative stress and transcriptional pathways of nuclear factor erythroid 2-related factor 2 (Nrf2) and nuclear factor kappa-B (NF-κB) are critically involved in the etiopathology of amebic liver abscess (ALA). In this work, we studied the relationship between the adrenergic nervous system and ALA in the hamster. ALA was visible at 12 h of infection. While 6-hydroxidopamine (6-OHDA) decreased infection, propranolol (β-adrenergic blocker) treatment was associated with less extensive liver damage, and phentolamine treatment (α-adrenergic blocker) significantly reduced ALA compared to 6-OHDA and propranolol. Serum enzymatic activities of alanine aminotransferase (ALT) and γ-glutamyl transpeptidase (γ-GTP) were increased at 12 h post-infection. Chemical denervation and α and β-adrenergic blockers decreased ALT to normal levels, while 6-OHDA and propranolol showed a trend to decrease γ-GTP but phentolamine significantly reduced γ-GTP. Amebic infection increased oxidized glutathione (GSSG) and decreased both reduced glutathione (GSH) and the GSH/GSSG ratio. Propranolol and 6-OHDA showed a tendency to decrease GSSG. However, GSH, GSSG and GSH/GSSG returned to normal levels with phentolamine. Furthermore, amebic infection increased pNF-κB and interleukin-1β (IL-1β), and showed a tendency to decrease hemoxigenase-1 (HO-1), but not Nrf2. Chemical denervation showed a trend to decrease pNF-κB and IL-1β, and neither Nrf2 nor HO-1 increased significantly. In addition, NF-κB and IL-1β were attenuated by propranolol and phentolamine treatments, although phentolamine showed significant overexpression of Nrf2 and HO-1. This suggests that the adrenergic system may be involved in oxidative stress and in modulation of the Nrf2 and NF-κB pathways during ALA development

X chromosome inactivation does not necessarily determine the severity of the phenotype in Rett syndrome patients

Rett syndrome (RTT) is a severe neurological disorder usually caused by mutations in the MECP2 gene. Since the MECP2 gene is located on the X chromosome, X chromosome inactivation (XCI) could play a role in the wide range of phenotypic variation of RTT patients; however, classical methylation-based protocols to evaluate XCI could not determine whether the preferentially inactivated X chromosome carried the mutant or the wild-type allele. Therefore, we developed an allele-specific methylation-based assay to evaluate methylation at the loci of several recurrent MECP2 mutations. We analyzed the XCI patterns in the blood of 174 RTT patients, but we did not find a clear correlation between XCI and the clinical presentation. We also compared XCI in blood and brain cortex samples of two patients and found differences between XCI patterns in these tissues. However, RTT mainly being a neurological disease complicates the establishment of a correlation between the XCI in blood and the clinical presentation of the patients. Furthermore, we analyzed MECP2 transcript levels and found differences from the expected levels according to XCI. Many factors other than XCI could affect the RTT phenotype, which in combination could influence the clinical presentation of RTT patients to a greater extent than slight variations in the XCI pattern