Efecto de la degradación por inmersión en acido nítrico sobre las propiedades de un poliéster reforzado con fibras de vidrio

The current article focuses on evaluating the effect of the half acid degradation in the mechanical and other properties and in the structural integrity of a polyester fiber-reinforced glass in two different orientation types:Mat, in taffeta and multiaxial fabrics, after the immersion process in nitric acid to 5 % of volume.El presente artículo se centra en evaluar el efecto de la degradación de un medio ácido en las propiedades mecánicas y térmicas, y en la integridad estructural de un poliéster reforzado con fibras de vidrio, en dos tipos diferentes de orientación: Mat, en tejidos tafetán, y Multiaxial, después del proceso de inmersión en ácido nítrico al 5% en volumen

Optimización de las propiedades de tracción de compuestos de matriz polimérica reforzada con partículas de magnetita por diseño experimental

A full-factorial 33 experiment was used in this study to determine the optimal values of the tensile properties of three composite materials manufactured based on three polymeric resins: Derakane Momentum epoxy vinyl ester based on bisphenol-A (DM-411), polyester based on terephthalic acid (P115-A), and isophthalic polyester (P2000). Such materials were reinforced with magnetite powders at concentrations of 10, 20, and 30 wt %, and the particle sizes were classified with three sieves: #200 (46–75 μm), #325 (26–45 μm), and #500 (0–25 μm). The compounds were manufactured using the hand lay-up method at room temperature in accordance with ASTM D638-14 for M1-type specimens. A tensile test was conducted on a universal Microtest EM2/300/FR machine at a test speed of 5 ± 25 % mm/min using an Epsilon extensometer calibrated in accordance with the ASTM E83 standard at 20 ± 2 °C. The magnetite powders and compound morphology were studied by Scanning Electron Microscopy. The mechanical properties of the compounds and the optimal response found by Analysis of Variance (ANOVA) and Response Surface Methodology (RSM) are also reported. The best response to the mechanical stimuli occurs with the composite material prepared with the epoxy vinyl ester resin DM-411, a concentration of 29.4 % of magnetite (Fe3O4), a particle size of 58.5 microns, and a 200 sieve.Un diseño factorial completo de 33 fue desarrollado con el fin de determinar los valores óptimos en las propiedades de tracción de tres tipos de materiales compuestos fabricados a base de resinas poliméricas epoxy-vinylester (DM-411) base bisfenol-A, poliéster (P115-A) base de ácido tereftálico, y poliéster (P2000) base de ácido isoftálico, reforzados con polvos de magnetita en concentraciones de 10, 20 y 30 % porcentaje en peso (Wt) con tres tamaños diferentes de partícula en el relleno, tamices #200 (46-75 μm), #325 (26-45 μm) y #500 (0-25 μm). Los compuestos se fabricaron utilizando el método de moldeo manual a temperatura ambiente, según ASTM D638-14 para muestras de tipo M1. Los ensayos de tracción se realizaron en una máquina universal microtest EM2/300/FR a una velocidad de prueba de 5 x 25 % mm/min, utilizando un extensómetro Epsilon calibrado de acuerdo con la norma ASTM E83 a 20°C. Los polvos de magnetita y la morfología de los materiales compuestos se estudiaron mediante microscopía electrónica de barrido. Se reportan las propiedades mecánicas de los compuestos y la respuesta óptima encontrada por análisis de varianza (ANOVA) y superficies de respuesta (RSM). La mejor respuesta a los estímulos mecánicos se produce con el material compuesto fabricado a base de resina epoxi -vinilester DM-411, con una concentración media de 29,4 % de magnetita Fe3O4 y tamaño medio de partícula de 58,5 micras la cual corresponde a un tamiz 200

Metodología para el diseño del método de explotación de arenas siliceas mediante el uso de software especializado

The methodologies used for the design of the method of sandstones explotation by descending staggered banks using specialized software tools are reported. The data analyzed were collected in the field for the operating license 14816 in Melgar, Tolima. The characterization of the rock mass was held from physical and mechanical tests, performed on cylindrical test tubes in order to obtain the value of the maximum strenght and elastic modulus of the rock. The direction and dip of the sandstone package was rock. The direction and dip of the sandstone package was determined by using the stereographic projection whit DIPS®  software, and the safety factor of the slope was obtained with established banks whit SLIDE® . The slops are 8 meters high and 8 meters wide whit a tilt angle 60°, which generated a safety factor  of 2.1. The design  of the mining method was carried out with GEOVIA SURPAC® , at an early stage of development ascending to the level 11 of the exploitation, to then start mining in descending order to control the stabiLity of slopes. The results obtained allow a general methodology for the development of projects to optimize the process of evaluation and selection of mining method by using specialized design tools.Se reporta la metodología utilizada para el diseño del método de explotación de areniscas por bancos escalonados descendentes utilizando herramientas de software especializado. Los datos analizados fueron recolectados en campo para la licencia de explotación 14816 en el municipio de Melgar departamento del Tolima, la caracterización del macizo rocoso se realizó a partir de pruebas físicas y mecánicas, sobre probetas cilíndricas con el fin de obtener el valor de la resistencia máxima y el módulo de elasticidad de la roca. El rumbo y buzamiento del paquete de areniscas se determinó mediante proyección estereográfica utilizando el software DISP®, y el factor de seguridad de los taludes se obtuvo con SLIDE® estableciéndose bancos de 8 metros de altura por 8 metros de ancho con un ángulo de inclinación de 60°, lo cual genero un factor de seguridad de 2.1. El diseño del método de explotación fue realizado con GEOVIA SURPAC®, en una fase inicial de desarrollo en forma ascendente hasta alcanzar el nivel 11 de la explotación, para luego iniciar la explotación en forma descendente con el fin de controlar la estabilidad los taludes. Los resultados obtenidos permiten establecer una metodología general, para la elaboración de proyectos tendientes a optimizar el proceso de evaluación y selección del método de explotación mediante el uso de herramientas especializadas de diseño

Aplicação de MgSO4 • 7H2O e cinzas voadoras como reforço na matriz de unidades cerâmicas maciças

Chemical compositions obtained by XRF from clay and fly ash from coal combustion in a hive furnace are reported. The quantities of clay, fly ash and magnesium sulphate (MgSO4 · 7H2O) were selected according to their chemical composition to achieve total efflorescence on the surface of the brick (solid ceramic unit). Once the masonry units were formed by pressing, they were treated at 400 °C for two hours to remove moisture, and once they reached 950 °C, they were cooked at this temperature for three hours. The chemical composition of the efflorescence on the surface of the specimens was established by XRF, the cross section of a brick was morphologically analyzed and, finally, the specimens were subjected to compression tests to determine their resistance and maximum water absorption, taking into account Colombian technical standard NTC 4205.Se reportan las composiciones químicas obtenidas por FRX de arcilla y cenizas volantes producto de la combustión de carbón en un horno tipo colmena. Se seleccionaron las cantidades de arcilla, ceniza volante y sulfato de magnesio (MgSO4 • 7H2O) en función de su composición química para lograr una eflorescencia total en la superficie del ladrillo (unidad cerámica maciza). Una vez se conformaron por prensado las unidades de mampostería, se sometieron a tratamiento a 400 °C durante dos horas con el fin de eliminar la humedad, una vez alcanzaron 950 °C se cocinan en esta temperatura durante tres horas. Se estableció la composición química de las eflorescencias en la superficie de las probetas por medio de FRX, se analizó morfológicamente el corte transversal de un ladrillo, y por último, las probetas se sometieron a ensayos de compresión para determinar su resistencia y de absorción máxima de agua, teniendo en cuenta la norma técnica colombiana NTC 4205.Relatam-se as composições químicas obtidas por FRX de argila e cinzas voadoras produto da combustão de carvão num forno tipo colmeia. Foram selecionadas as quantidades de argila, cinza voadora e sulfato de magnésio (MgSO4 • 7H2O) em função de sua composição química para atingir uma eflorescência total na superfície do tijolo (unidade cerâmica maciça). Assim que as unidades de alvenaria foram prensadas, foram submetidas a tratamento a 400 °C durante duas horas, a fim de eliminar a umidade; uma vez tenham atingido 950 °C, foram cozidas nessa temperatura durante três horas. Foi estabelecida a composição química das eflorescências na superfície das provetas por meio de FRX; logo, foi analisado morfologicamente o corte transversal de um tijolo e, por último, as provetas foram submetidas a ensaios de compressão para determinar sua resistência e absorção máxima de água, considerando a norma técnica colombiana NTC 4205

"INTERGROWTH21st vs customized fetal growth curves in the assessment of the neonatal nutritional status: a retrospective cohort study of gestational diabetes"

Background Gestational diabetes mellitus is associated with increased incidence of adverse perinatal outcomes including newborns large for gestational age, macrosomia, preeclampsia, polyhydramnios, stillbirth, and neonatal morbidity. Thus, fetal growth should be monitored by ultrasound to assess for fetal overnutrition, and thereby, its clinical consequence, macrosomia. However, it is not clear which reference curve to use to define the limits of normality. Our aim is to determine which method, INTERGROWTH21st or customized curves, better identifies the nutritional status of newborns of diabetic mothers. Methods This retrospective cohort study compared the risk of malnutrition in SGA newborns and the risk of overnutrition in LGA newborns using INTERGROWTH21st and customized birth weight references in gestational diabetes. The nutritional status of newborns was assessed using the ponderal index. Additionally, to determine the ability of both methods in the identification of neonatal malnutrition and overnutrition, we calculate sensitivity, specificity, positive predictive value, negative predictive value and likelihood ratios. Results Two hundred thirty-one pregnant women with GDM were included in the study. The rate of SGA indentified by INTERGROWTH21st was 4.7% vs 10.7% identified by the customized curves. The rate of LGA identified by INTERGROWTH21st was 25.6% vs 13.2% identified by the customized method. Newborns identified as SGA by the customized method showed a higher risk of malnutrition than those identified as SGA by INTERGROWTH21st. (RR 4.24 vs 2.5). LGA newborns according to the customized method also showed a higher risk of overnutrition than those classified as LGA according to INTERGROWTH21st. (RR 5.26 vs 3.57). In addition, the positive predictive value of the customized method was superior to that of INTERGROWTH21st in the identification of malnutrition (32% vs 27.27%), severe malnutrition (22.73% vs 20%), overnutrition (51.61% vs 32.20%) and severe overnutrition (28.57% vs 14.89%). Conclusions In pregnant women with DMG, the ability of customized fetal growth curves to identify newborns with alterations in nutritional status appears to exceed that of INTERGROWTH21s

Caracterización morfológica y estructural del cascarón cerámico desecho del proceso de microfundición en FASAB Sogamoso

The structural characteristics and the crystalline parameters of the waste material in the process of investment casting in the Military Industry (INDUMIL for its acronym in Spanish) Factory Santa Barbara are reported. By performing standard laboratory tests such as Optical Microscopy, Scanning Electron Microscopy (SEM) and X-ray Diffraction (XRD), particle size distribution, porosity and fractures present are identified. In addition, a qualitative and quantitative analysis of mineral phases is performed by determining the major phase and comparing the phases present in the original feedstock. Finally,based on information obtained, possible uses that may have the material under study are proposed.Se reportan las características estructurales y los parámetros cristalinos del material de desecho del proceso de microfundición en la Industria Militar (INDUMIL) Fábrica Santa Bárbara. Mediante la realización de pruebas normalizadas de laboratorio, tales como microscopía óptica, microscopia electrónica de barrido (MEB) y difracción de rayos X (DRX), se identifican la distribución granulométrica, la porosidad y las fracturas presentes. Además, se realiza un análisis cualitativo y cuantitativo de las fases mineralógicas, determinando la fase mayoritaria y comparándola con las fases presentes en la materia prima original. Finalmente, con base en la información obtenida, se proponen posibles usos que pueda tener el material en estudio

Influence of dietary fiber upon in vitro microbial cecal fermentation in mexican hairless and mexican cuino pigs

The objective of the present study was to evaluate and compare the in vitro cecal fermentation (by the gas production technique), in Mexican hairless pig (MHP) and Mexican cuino pig (MCP), adding cellulose or starch as substrates (0, 100, 200, 300 and 400 mg/g DM). 12 pigs were slaughtered (BW= 104±0.5 kg), six of each genotype were collected from the cecal contents and there was a pool for every two pigs in each genotype, and thereafter, for each substrate (cellulose or starch) in its different concentration, three flasks were incubated with inoculum for each pool and made three series of incubation. The experimental design use the effect of genotype, substrate and concentration of the substrate added on the variables of in vitro fermentation. The averages of the data were compared by Tukey's method. In vitro gas production was higher (P<0.05) (mL/g DM) for MHP (206.8) vs MCP (180.2). The degradation fractional rate rhythm (b, 0.094 and c, -0.0127) and lag time (1.79) of the MHP was higher than MCP (b, 0.074; c -0.102) and lag time (1.26); with the addition of carbohydrates as substrates, in vitro gas production of potato starch was higher (P<0.05) than cellulose (238.3 vs 148.7 mL/g DM); the fractions b, c and lag time, there were differences (P<0.05) between substrates. The increasing addition of cellulose or starch had a lineal effect (P<0.05) with the gas production, level cero mg (133.46) to 400 mg of substrate (263.16 mL/g DM). MHP had a higher cecal fermentation than MCP, being higher the gas production at 9 and 12 h, there was higher gas production (cecal fermentation) when added starch as substrate

INTERGROWTH-21st versus a customized method for the prediction of neonatal nutritional status in hypertensive disorders of pregnancy

Background Hypertensive disorders of pregnancy (HDP) generate complications and are one of the principal causes of maternal, foetal, and neonatal mortality worldwide. It has been observed that in pregnancies with HDP, the incidence of foetuses small for their gestational age (SGA) is twice as high as that in noncomplicated pregnancies. In women with HDP, the identification of foetuses (SGA) is substantially important, as management and follow-up are determined by this information. Objective The objective of this study was to evaluate whether the INTERGROWTH-21st method or customized birthweight references better identify newborns with an abnormal nutritional status resulting from HDP. Method A comparative analysis study was designed with two diagnostic methods for the prediction of neonatal nutritional status in pregnancies with HDP. The performance of both methods in identifying neonatal malnutrition (defined by a neonatal body mass index < 10(th) centile or a ponderal index < 10(th) centile) was assessed by calculating sensitivity, specificity, positive predictive value, negative predictive value, diagnostic odds ratio, Youden's index and probability ratios. Results The study included 226 pregnant women diagnosed with HDP. The customized method identified 45 foetuses as small for gestational age (19.9%), while the INTERGROWTH-21st method identified 27 newborns with SGA (11.9%). The difference between proportions was statistically significant (p < 0.01). Using body mass index (< 10(th) centile) as a measure of nutritional status, newborns identified as SGA by the customized method showed a higher risk of malnutrition than those identified as SGA by INTERGROWTH-21st (RR: 4.87 (95% CI: 1.86-12.77) vs. 3.75 (95% CI: 1.49-9.43)) (DOR: 5.56 (95% CI: 1.82-16.98) vs. 4.84 (95% CI: 1.51-15.54)) Even when using Ponderal index (< 10(th) centile), newborns identified as SGA by the customized method showed a higher risk of malnutrition than those identified as SGA by INTERGROWTH-21st (RR 2.37 (95% CI: 1.11-5.05) vs. 1.68 (95% CI: 0.70-4.03))(DOR 2.62 (95% CI: 1.00-6.87) vs. 1.90 (95% CI: 0.61-5.92)). Conclusion In pregnant women with HDP, the predictive ability of the customized foetal growth curves to identify neonatal malnutrition appears to surpass that of INTERGROWTH-21st

Laser Shock Processing: An Advanced Technique for Improving the Surface and Mechanical Properties of Metallic Alloys

Profiting by the increasing availability of laser sources delivering intensities above 10 9W/cm2 with pulse energies in the range of several Joules and pulse widths in the range of nanoseconds, laser shock processing (LSP) is being consolidating as an effective technology for the improvement of surface and mechanical resistance properties of metals and is being developed as a practical process amenable to production engineering. The main acknowledged advantage of the laser shock processing technique consists on its capability of inducing a relatively deep compression residual stresses field into metallic alloy pieces allowing an improved mechanical behaviour, explicitly, the life improvement of the treated specimens against wear, crack growth and stress corrosion cracking. Following a short description of the theoretical/computational and experimental methods developed by the authors for the predictive assessment and experimental implementation of LSP treatments, experimental results on the residual stress profiles and associated surface properties modification successfully reached in typical materials (specifically steels and Al and Ti alloys) under different LSP irradiation conditions are presented. In particular, the analysis of the residual stress profiles obtained under different irradiation parameters and the evaluation of the corresponding induced surface properties and fatigue life enhancement are presented

Utilización de estructuras verbales en la identificación de relaciones y descriptores en tesauros

Se parte del desarrollo que los tesauros automatizados han proporcionado a las llamadas relaciones no-clásicas de Van Slype, fomentando una eclosión de las relaciones de asociación, agrupadas en categorías por Tudhope, Alani, Jones y engrosadas por el traspaso de relaciones antes de jerarquía por la American Library Association (ALA). Frente a la estaticidad y clasificación taxonómica de los tesauros clásicos, inadaptados al dinamismo, transversalidad, exigencia de mayor abstracción de la información en hipermedia, se proponen las formas verbales como conceptos dinámicos, relacionales, conceptualizadores de la acción, muy útiles para representar el contexto mediante relaciones circunstanciales, a partir de los precedentes establecidos por A. L. Tharp y SYNTOL. Se ndican como sus aplicaciones inmediatas la determinación de géneros de Swales, la tipología de las secciones del documento y unas funciones tesaurales más eficaces en red. Se concluye con futuros desarrollos de investigación en las categorizaciones asociativas, desde las experiencias aplicativas deWordNet.Este trabajo ha sido realizado dentro del marco del Proyecto financiado por la CICYT (Comisión Interministerial de Ciencia y Tecnología), titulado “Desarrollo de un tesauro de verbos para entornos de información dinámica. Aplicación del estándar ISO/ICE: 13250:1999, del Plan General del Conocimiento. TIC 2000-2003