Characterisation of PVD-TiN coated austempered ductile iron: Effects of nodule count and austempering temperature

In this work PVD-TiN coatings are deposited on ADI substrates austempered at 280 and 360°C, with nodule counts varying between 490 and 1 100 nod/mm2. The deposition is performed at 300°C by the arc ion plating technique. The effects of the substrates' microstructure on the characteristics of the coatings and the possible changes in ausferritic microstructure owing to the effects of the deposition process are evaluated. The existing phases, preferred orientation, film thickness, hardness, Young's modulus, surface topography and adhesion of each coated sample are determined. A metallographic characterisation of the ausferritic matrices and determination of the retained austenite content are performed before and after deposition. The results obtained indicate that PVD-TiN coatings feature a preferred orientation of (111) planes parallel to the surface and film thicknesses of about 2m m. Knoop hardness is influenced by the substrates characteristics, the values range from 1 700 to 2 100 HK0.015. Nanohardness values are close to 25 GPa, while Young's modulus shows some scattering (323 to 336 GPa). The surface topography is dependent on the microstructure of the substrates and the surface preparation method employed as well as on the deposition process used. The adhesion strength quality of the coatings, according to the Rockwell-C adhesion test, can be related to HF1-HF2 and is affected neither by the hardness differences between the different substrates nor by the nodule count variation. After the coating process, the microstructure of ADI substrates only suffers negligible changes and the amount of retained austenite decreases slightly.Fil: Colombo, Diego Alejandro. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones en Ciencia y Tecnología de Materiales. Universidad Nacional de Mar del Plata. Facultad de Ingeniería. Instituto de Investigaciones en Ciencia y Tecnología de Materiales; ArgentinaFil: Echeverría, María D.. Universidad Nacional de Mar del Plata; ArgentinaFil: Moncada, Osvaldo Julio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones en Ciencia y Tecnología de Materiales. Universidad Nacional de Mar del Plata. Facultad de Ingeniería. Instituto de Investigaciones en Ciencia y Tecnología de Materiales; ArgentinaFil: Massone, Juan Miguel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones en Ciencia y Tecnología de Materiales. Universidad Nacional de Mar del Plata. Facultad de Ingeniería. Instituto de Investigaciones en Ciencia y Tecnología de Materiales; Argentin

Comportamiento mecánico de ADI tratada superficialmente mediante la aplicación de recubrimientos PVD de baja temperatura

En este trabajo se aplican recubrimientos PVD de TiN y CrN sobre ADI y se analiza la influencia del material del recubrimiento sobre las propiedades mecánicas del producto ADI recubierto. Se analiza también, el efecto del proceso de deposición sobre la microestructura de los sustratos. Los recubrimientos se aplican en un reactor industrial mediante la técnica de plateado iónico con arco catódico, utilizando parámetros de proceso específicamente seleccionados para este material. Se determinan fases presentes, orientación preferencial, topografía superficial, espesor de película, dureza, tensiones residuales, adherencia y coeficiente de fricción de las muestras recubiertas. Además, se determina la cantidad de austenita retenida presente en los sustratos antes y después de las deposiciones. Los resultados obtenidos muestran que los recubrimientos de TiN y CrN aplicados sobre muestras de ADI a una temperatura de 300ºC y con tiempos de deposición de hasta 180 min presentan muy buenas características en cuanto a espesor de película, dureza, tensiones residuales y adherencia, sin producir deterioro de la microestructura ausferrítica. Los procesos de deposición modifican la topografía superficial de las muestras, produciendo un aumento de la rugosidad media. Las muestras recubiertas con TiN presentan mayores durezas y tensiones residuales. Las muestras sin recubrir y recubiertas con TiN muestran coeficientes de fricción similares, mientras que las muestras recubiertas con CrN coeficientes significativamente inferiores. Los ensayos de deslizamiento no produjeron la fractura y/o delaminación de los recubrimientos en ningún caso.Fil: Colombo, Diego Alejandro. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Mar del Plata. Instituto de Investigación en Ciencia y Tecnología de Materiales (i); Argentina; Universidad Nacional de Mar del Plata; Argentina;Fil: Echeverría, María D.. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Mar del Plata. Instituto de Investigación en Ciencia y Tecnología de Materiales (i); Argentina; Universidad Nacional de Mar del Plata; Argentina;Fil: Massone, Juan Miguel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Mar del Plata. Instituto de Investigación en Ciencia y Tecnología de Materiales (i); Argentina; Universidad Nacional de Mar del Plata; Argentina

Mechanical and tribological behavior of Ti/TiN and TiAl/TiAlN coated austempered ductile iron

Bilayer Ti/TiN and TiAl/TiAlN coatings were deposited onto austempered ductile iron (ADI) substrates by cathodic arc deposition in an industrial device. Structure and mechanical properties of the coated samples were comparatively examined. Wear behavior of the coated samples was investigated in comparison with uncoated ADI by means of rolling contact fatigue (RCF) tests, performed in a flat washer type testing rig and using lubricated pure rolling conditions. RCF tests results were analyzed using the two-parameter Weibull distribution and the Weibayes method. The results indicate that TiN and TiAlN coatings grew with a cubic-NaCl type structure. The arithmetic average roughness of the coated samples is similar for both coating variants. The surface hardness and residual stresses are higher for the TiAl/TiAlN coated samples. The coating hardness and elastic modulus are also higher for TiAl/TIAlN. The critical loads at massive delamination and the evolution of the friction coefficients are quite similar for both coating variants. Regarding RCF, failures in coated samples were characterized by substrate spalling. No massive delamination was observed in Ti/TiN and TiAl/TiAlN coatings. The statistical analysis indicates that the deposition of Ti/TiN improves noticeably the RCF resistance of ADI while the deposition of TiAl/TiAlN does not produce significant changes. The properties mismatch between substrate and coating seems to play an important role in the RCF behavior of coated samples, since Ti/TiN coatings possess a lower mismatch with respect to ADI substrates as compared to TiAl/TiAlN.Fil: Colombo, Diego Alejandro. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones en Ciencia y Tecnología de Materiales. Universidad Nacional de Mar del Plata. Facultad de Ingeniería. Instituto de Investigaciones en Ciencia y Tecnología de Materiales; ArgentinaFil: Mandri, Alejo Daniel. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Echeverría, María D.. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Massone, Juan Miguel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones en Ciencia y Tecnología de Materiales. Universidad Nacional de Mar del Plata. Facultad de Ingeniería. Instituto de Investigaciones en Ciencia y Tecnología de Materiales; ArgentinaFil: Dommarco, Ricardo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones en Ciencia y Tecnología de Materiales. Universidad Nacional de Mar del Plata. Facultad de Ingeniería. Instituto de Investigaciones en Ciencia y Tecnología de Materiales; Argentin

Survey of diseases affecting reproduction in freeze bovine semen using the polymerase chain reaction (PCR)

Las enfermedades reproductivas son una de las principales causas de los bajos índices de procreo en Uruguay. El diagnóstico de estas enfermedades se lleva a cabo por diversas técnicas de laboratorio; la mayoría de las cuales no permiten la diferenciación de las distintas subespecies de cada microorganismo, hecho que si se puede determinar por medio de la técnica de PCR. En este estudio se intentó determinar la presencia de genomas de: Diarrea Viral Bovina, Herpesvirus bovino tipos 1 y 5, Campylobacter fetus fetus y fetus veneralis y Tritrichomonas foetus foetus. Para ello, 100 pajuelas de semen de bovinos de distintas razas fueron procesadas mediante PCR utilizando “primers” específicos para cada una de las enfermedades en estudio. Todas las muestras analizadas resultaron negativas a la detección de genomas de los agentes mencionados. Esta investigación permitió comprobar el buen nivel de los centros de reproducción evaluados, repercutiendo favorablemente en la sanidad del rodeo nacional. Así mismo, el chequeo de pajuelas de semen por medio de la técnica de PCR demostró ser una herramienta necesaria que debería ser utilizada de rutina ya que permite un rápido y eficiente diagnóstico.Reproductive diseases are a major cause of low calving rates nationwide. The diagnosis of these diseases is performed by various laboratory techniques, most of them do not allow differentiation in different subspecies of each organism, a fact that it can be determined by PCR. This study attempted to determine the presence of genome of bovine viral diarrhea, bovine herpesvirus types 1 and 5, Campylobacter fetus fetus and fetus veneralis and Tritrichomonas foetus foetus. One hundred bovine semen straws were collected and PCR technique using specific primers for each of the diseases studied were applied. All samples were negative for the detection of genomes of the pathogens mentioned. This investigation allowed to check the proper level of insemmination centers evaluated, impacting positively on the health of the national herd. Likewise, the screening of bovine semen straws by PCR proved to be a necessary tool that would be used routinously for quick and efficient diagnosis.Facultad de Ciencias Veterinaria

Survey of diseases affecting reproduction in freeze bovine semen using the polymerase chain reaction (PCR)

Las enfermedades reproductivas son una de las principales causas de los bajos índices de procreo en Uruguay. El diagnóstico de estas enfermedades se lleva a cabo por diversas técnicas de laboratorio; la mayoría de las cuales no permiten la diferenciación de las distintas subespecies de cada microorganismo, hecho que si se puede determinar por medio de la técnica de PCR. En este estudio se intentó determinar la presencia de genomas de: Diarrea Viral Bovina, Herpesvirus bovino tipos 1 y 5, Campylobacter fetus fetus y fetus veneralis y Tritrichomonas foetus foetus. Para ello, 100 pajuelas de semen de bovinos de distintas razas fueron procesadas mediante PCR utilizando “primers” específicos para cada una de las enfermedades en estudio. Todas las muestras analizadas resultaron negativas a la detección de genomas de los agentes mencionados. Esta investigación permitió comprobar el buen nivel de los centros de reproducción evaluados, repercutiendo favorablemente en la sanidad del rodeo nacional. Así mismo, el chequeo de pajuelas de semen por medio de la técnica de PCR demostró ser una herramienta necesaria que debería ser utilizada de rutina ya que permite un rápido y eficiente diagnóstico.Reproductive diseases are a major cause of low calving rates nationwide. The diagnosis of these diseases is performed by various laboratory techniques, most of them do not allow differentiation in different subspecies of each organism, a fact that it can be determined by PCR. This study attempted to determine the presence of genome of bovine viral diarrhea, bovine herpesvirus types 1 and 5, Campylobacter fetus fetus and fetus veneralis and Tritrichomonas foetus foetus. One hundred bovine semen straws were collected and PCR technique using specific primers for each of the diseases studied were applied. All samples were negative for the detection of genomes of the pathogens mentioned. This investigation allowed to check the proper level of insemmination centers evaluated, impacting positively on the health of the national herd. Likewise, the screening of bovine semen straws by PCR proved to be a necessary tool that would be used routinously for quick and efficient diagnosis.Facultad de Ciencias Veterinaria

Primer análisis de la secuencia completa del gen VP2 de una cepa local de parvovirus porcino

El parvovirus porcino (PPV) es uno de los agentes infecciosos más importantes que se asocia a fallas reproductivas en granjas porcinas. En Argentina, como en otros países donde la producción porcina es de importancia económica, estas fallas son un gran problema. El PPV es un virus con genoma ADN monocatenario (cadena negativa) de aproximadamente 5000 nt. La cápside es icosaédrica, no envuelta y está formada por copias múltiples de VP1, VP2 y VP3. En los últimos años, se viene reportando una variación genética entre las cepas de campo y las cepas de referencia y/o vacunales. Además, se sabe que las cepas de PPV se pueden distinguir por su diferente patogenicidad; las sustituciones de pocos residuos en la VP2 (D378G, H383Q y S436P), son responsables de las distintas propiedades biológicas entre las cepas NADL-2 y Kresse (vacuna y salvaje, respectivamente). El objetivo de este trabajo fue amplificar por PCR el gen completo de la VP2 de una cepa local y analizar la secuencia respecto de cepas vacunales y de referencias publicadas en el Genbank.Trabajo publicado en Cagliada, Maria del Pilar Lilia y Galosi, Cecilia Mónica (comps.). I Congreso de Microbiología Veterinaria. Libro de resúmenes. La Plata: Facultad de Ciencias Veterinarias, 2021.Facultad de Ciencias Veterinaria

Multiparametric renal magnetic resonance imaging: A reproducibility study in renal allografts with stable function

Monitoring renal allograft function after transplantation is key for the early detection of allograft impairment, which in turn can contribute to preventing the loss of the allograft. Multiparametric renal MRI (mpMRI) is a promising noninvasive technique to assess and characterize renal physiopathology; however, few studies have employed mpMRI in renal allografts with stable function (maintained function over a long time period). The purposes of the current study were to evaluate the reproducibility of mpMRI in transplant patients and to characterize normal values of the measured parameters, and to estimate the labeling efficiency of Pseudo-Continuous Arterial Spin Labeling (PCASL) in the infrarenal aorta using numerical simulations considering experimental measurements of aortic blood flow profiles. The subjects were 20 transplant patients with stable kidney function, maintained over 1 year. The MRI protocol consisted of PCASL, intravoxel incoherent motion, and T1 inversion recovery. Phase contrast was used to measure aortic blood flow. Renal blood flow (RBF), diffusion coefficient (D), pseudo-diffusion coefficient (D*), flowing fraction ( f ), and T1 maps were calculated and mean values were measured in the cortex and medulla. The labeling efficiency of PCASL was estimated from simulation of Bloch equations. Reproducibility was assessed with the within-subject coefficient of variation, intraclass correlation coefficient, and Bland-Altman analysis. Correlations were evaluated using the Pearson correlation coefficient. The significance level was p less than 0.05. Cortical reproducibility was very good for T1, D, and RBF, moderate for f , and low for D*, while medullary reproducibility was good for T1 and D. Significant correlations in the cortex between RBF and f (r = 0.66), RBF and eGFR (r = 0.64), and D* and eGFR (r = -0.57) were found. Normal values of the measured parameters employing the mpMRI protocol in kidney transplant patients with stable function were characterized and the results showed good reproducibility of the techniques

A stochastic evaluation of the validity of an animal-health survey in Uruguay

This paper introduces spreadsheet simulation models to evaluate the validity of national or regional disease surveys aimed at identifying infection in populations of farm animals. The process of evaluation includes specification or calculation of cluster-level diagnostic test sensitivity (the proportion of animals with the disease which test positive) and specificity (the proportion of animals without the disease which test negative), which are obtained from two probability distributions of the number of positive tests at individual-level expected from infected and non-infected clusters, respectively. Probability distributions for the number of positive clusters expected in a situation of the herd prevalence are specified and used to define survey properties (the survey being considered a diagnostic system), and receiver operating characteristic curves (consisting of a plot of sensitivity and specificity pairs for different cut-off values) are drawn. The result of a survey implemented to determine the prevalence of infectious bovine rhinotracheitis in dairy cattle in Uruguay, South America was used to illustrate this approach. The models can be adapted to a wide range of survey designs in animal health and production.Facultad de Ciencias Veterinaria

Impairment of exogenous lactate clearance in experimental hyperdynamic septic shock is not related to total liver hypoperfusion

Introduction: Although the prognostic value of persistent hyperlactatemia in septic shock is unequivocal, its physiological determinants are controversial. Particularly, the role of impaired hepatic clearance has been underestimated and is only considered relevant in patients with liver ischemia or cirrhosis. Our objectives were to establish whether endotoxemia impairs whole body net lactate clearance, and to explore a potential role for total liver hypoperfusion during the early phase of septic shock. Methods: After anesthesia, 12 sheep were subjected to hemodynamic/perfusion monitoring including hepatic and portal catheterization, and a hepatic ultrasound flow probe. After stabilization (point A), sheep were alternatively assigned to lipopolysaccharide (LPS) (5 mcg/kg bolus followed by 4 mcg/kg/h) or sham for a three-hour study period. After 60 minutes of shock, animals were fluid resuscitated to normalize mean arterial pressure. Repeated series of measurements were performed immediately after fluid resuscitation (point B), and one (point C) and two hours later (point D). Monitoring included systemic and regional hemodynamics, blood gases and lactate measurements, and ex-vivo hepatic mitochondrial respiration at point D. Parallel exogenous lactate and sorbitol clearances were performed at points B and D. Both groups included an intravenous bolus followed by serial blood sampling to draw a curve using the least squares method. Results: Significant hyperlactatemia was already present in LPS as compared to sham animals at point B (4.7 (3.1 to 6.7) versus 1.8 (1.5 to 3.7) mmol/L), increasing to 10.2 (7.8 to 12.3) mmol/L at point D. A significant increase in portal and hepatic lactate levels in LPS animals was also observed. No within-group difference in hepatic DO2, VO2 or O2 extraction, total hepatic blood flow (point D: 915 (773 to 1,046) versus 655 (593 to 1,175) ml/min), mitochondrial respiration, liver enzymes or sorbitol clearance was found. However, there was a highly significant decrease in lactate clearance in LPS animals (point B: 46 (30 to 180) versus 1,212 (743 to 2,116) ml/min, P <0.01; point D: 113 (65 to 322) versus 944 (363 to 1,235) ml/min, P <0.01). Conclusions: Endotoxemia induces an early and severe impairment in lactate clearance that is not related to total liver hypoperfusion