2,735 research outputs found
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
COVID-19, activity and mobility patterns in Bogotá. Are we ready for a ‘15-minute city’?
Social distancing and economic lockdown measures implemented in Global North countries have been mimicked in the Global South to contain the spread of COVID-19. However, the consequences of such measures on activity and mobility patterns among social groups in Global South cities remain unclear. This paper seeks to provide reliable evidence from changes in behaviors across income groups at the urban scale. We report a detailed analysis from a web-based survey to understand the effects of the early and complete lockdown adopted to contain the COVID-19 spread on activity and travel patterns in Bogotá. We also performed a geographical proximity analysis of non-work services and facilities located around surveyed households to challenge the rhetoric about the ‘15-minute’ city. We found that low-income people are more socially exposed to contagion being forced to go out to find their daily sustenance and having adverse economic and travel effects than other income groups. However, even though Bogotá is not so far from meeting the goal of 15 min proximity, particularly for non-work-related activities, we found marked inequalities among income groups regarding access to essential services in proximity. The paper’s findings serve as a reminder that travel behavior and accessibility are not the remits of only urban transport planning and that land-use and urban planning play a determining role in redressing social and spatial inequalities in a city
Asociación entre Trastornos Óseos Degenerativos y Acumulación de Líquido en los Recesos de la Articulación Temporomandibular
ResumenEl Objetivo del presente estudio fue determinar la asociación entre presencia de líquido intra-articular y alteraciones degenerativas en las ATM de pacientes adultos con diagnóstico clínico de Trastornos Temporomandibulares, por medio de diagnóstico imagenológico, antes de iniciar su tratamiento.Material y MétodoSe reclutaron 135 pacientes consecutivos (promedio de edad = 33,3 años) que clínicamente presentan disfunciones de las ATM y que fueron examinados por medio de Resonancia Magnética (RM) y Tomografía Computada (TC). Los criterios de exclusión fueron: pacientes menores de 16 años, pacientes mayores de 65 años, pacientes portadores de prótesis dentarias removibles, con enfermedades sistémicas como gota, Osteoartrosis sistémica, hiperlaxitud ligamentaria, malformaciones anatómicas, enfermedades quísticas, tumorales, historia de trauma o cirugía de las ATM. Todos los pacientes fueron examinados utilizando el resonador magnético [Phillips Intera 1,5 T, bobina Sense Flex S Dual] en las secuencias; sagital DP-T2-Spir, coronal DP y dinámico ECHO gradiente y también fueron examinados por medio de Tomografía Computada (TC), con cortes de volúmenes-axiales y volúmenes-coronales de 625um de espesor [BrightSpeed®ELITE, General Electric, Milwaukee, USA)] tanto a boca abierta como cerrada, bajo los siguientes parámetros: FOV: 16.0cms, Algoritmo Hueso, Filtro Edge A2 y Matriz 512x512 pxs]. Los estudios imagenológicos de las ATMs formaron los siguientes ocho grupos: Grupo A: Ausencia de líquido (L) en ATM Derecha con Alteración Degenerativa (AD); Grupo B: Presencia de Líquido en ATM Derecha con AD; Grupo C: Ausencia de Líquido en ATM Izquierda con AD; Grupo D: Presencia de L en ATM Izquierda con AD; Grupo E: Ausencia de AD y Ausencia de L en ATM Derecha; Grupo F: Ausencia de AD y Presencia de L en ATM Derecha; Grupo G: Ausencia de L en ATM Izquierda; Grupo H: Presencia de L y ausencia de AD en ATM Izquierda. Los datos fueron analizados estadísticamente con la prueba Chi2 (Systat v12.0).ResultadoGrupo A: n= 61; Grupo B: n= 64; Grupo C: n= 54; Grupo D: n= 53; Grupo E; n=12; Grupo F; n=13; Grupo G: n=8 y Grupo H: n=5.ConclusiónNo existe asociación entre la presencia de líquido intra-articular y Alteraciones Degenerativas de las superficies articulares en la ATM.AbstractThe Objective of the present study was to determine the association between articular space effusion and degenerative bone disease in adult TMJ with internal derangement, previous any treatment, by images diagnosis.Materials y MethodsWere recruited 135 consecutives patients (X=33.3 years) that presented TMJ dysfunction were examined using Magnetic Resonance (MRI) [Phillips Intera 1,5 T, Sense Flex S Dual Coil] in sequences; sagital DP-T2-Spir, coronal DP and dynamic ECHO gradient and using Computed Tomography (TC) by axial-volumes slices and coronal-volumes slices of 625um of width [BrightSpeed®ELITE, General Electric, Milwaukee, USA], with the patient in open mouth and closed mouth under the next parameters: FOV: 16.0cms, Bone Algorithm, Edge Filter A2 and Matrix 512x512 pxs. The exclusion criteria was: patients below 16 years and above 65 years of age, patients using removable dental prosthetics, patients that presented systemic disease such as Gout Disease, Osteoarthrosis and hipermobility, anatomic structural alterations, Quistic or Tumor disease and TMJ surgery. The TMJ images studies formed the following eight groups: Group A: Absence of effusion (L) in right TMJ with Degenerative Disease (AD); Group B: Presence of L in right TMJ with AD; Grupo C: Absence of L in left TMJ with AD; Group D: Presence of L in left TMJ with AD; Group E: Absence of AD and absence of L in right TMJ; Group F: Absence of AD and presence of L in right TMJ; Group G: Absence of L in left TMJ; Group H: Presence of L and absence of AD in left TMJ. Data were statistically analyzed by Chi2 (Systat v12.0).ResultsGroup A: n= 61; Group B: n= 64; Group C: n= 54; Group D: n= 53; Group E; n=12; Group F; n=13; Group G: n=8 y Group H: n=5.ConclusionNo association was found between Degenerative Bone Disease and Temporo mandibular Joint Articular Space Effusion in TMJ
Human colon cancer cell lines show a diverse pattern of nitric oxide synthase gene expression and nitric oxide generation.
A panel of human colonic adenocarcinoma cell lines was examined both for expression of mRNAs of the nitric oxide synthase (NOS) gene family and for evidence of enzymic activity based on citrulline and nitrite (NO2-) formation. Reverse transcription-polymerase chain reaction (RT-PCR), revealed that all lines (SW480, SW620, DLD-1 and WiDr) expressed mRNA for the Ca(2+)-dependent endothelial (e)NOS, while SW480 cells also expressed the Ca(2+)-dependent neuronal (n)NOS. The mRNA for the Ca(2+)-independent inducible (i)NOS was expressed both by cytokine-stimulated and by unstimulated SW480, SW620 and DLD-1 cells, but none was seen at any time in the WiDr cells. There was, however, little correlation between mRNA expression and enzymic activity based on citrulline and NO2- formation. Thus none of the cell lines exhibited measurable Ca(2+)-dependent NOS activity, while Ca(2+)-independent NOS activity was seen in all but the WiDr cells. Furthermore, DLD-1 cells generated citrulline with resultant NO2- formation only after stimulation with lipopolysaccharide (LPS) and/or cytokines, while SW480 and SW620 did so constitutively. Thus RT-PCR studies indicate that tumour cells of similar epithelial origin display a diverse pattern of NOS gene family expression, and parallel biochemical studies clearly indicate that such expression does not always result in measurable enzymic activity leading to the generation of NO
Forage Production is Not Changed in Dwarf Elephantgrass Swards Managed in a Wide Range of Pre-Grazing Canopy Heights
Height corresponding to the critical leaf area index (LAI) has been successfully used to define pre-grazing management targets in pastures subjected to intermittent stocking. However, studies on short/stoloniferous grasses have demonstrated that it is possible to manage pastures at heights below those corresponding to the critical LAI (with a threshold grazing height of approximately 65% of those corresponding to the critical LAI) and achieve a similar forage yield, provided that the severity of defoliation does not exceed 50 percent of the pre-grazing height. In this study, we hypothesized that in tall tussock grasses (such as elephant grass), the amplitude of grazing height required to maintain the same forage yield is lower than that generally observed in small/stoloniferous grasses. Pennisetum purpureum Schum. BRS Kurumi\u27s elephant grass pastures were grazed at three different heights (50, 65, and 80 cm), leaving residual heights of 25, 32, and 40 cm. Our preliminary results suggest that under moderate defoliation and no nutrient limitations, tall tussock-forming grasses exhibit forage accumulation flexibility in the same range of management heights as grasses of smaller size and growth habits. In the present study, elephant grass cv. Kurumi these heights corresponded to a pre-grazing height range of 50 to 80 cm
Tuning the hydrogenation of CO2 to CH4 over mechano-chemically prepared palladium supported on ceria
Evaluation of soil physical quality index S for some tropical and temperate medium-textured soils
Aerobic fitness and neurocognitive performance in older adults from Kansas and Costa Rica
Background and Objectives: There is a dearth of comparative studies on the association between aging, cognitive function and cardiorespiratory fitness in older adults from developed and developing countries. The purpose of the study was to determine the association between aerobic power and neurocognitive performance in older adults from the Kansas (KS, USA) and Costa Rica (CR). Research Design and Methods: In a cross-sectional study, older adults from CR (n = 78) and KS (n = 100) underwent a maximal cardiopulmonary function test to determine aerobic power and a comprehensive battery of cognitive function dimensions including a cognitive screen, and tests of simple speed of processing, spatial visualization, visuospatial processing, episodic memory and verbal abilities, executive functioning and cognitive control, and working memory tasks. Raw data from the dimensions were z-transformed to compute an overall index of global neurocognitive performance. Results: Aerobic power was similar between male and female older adults from CR and KS. Regardless of gender, elderly from CR scored lower in cognitive measures than elderly from KS. For the entire sample, a small correlation was found between aerobic power and Visuospatial processing/fluid ability (r = 0.197, p = 0.009). Discussion and Implications: Elderly males and females from KS and CR reported similar aerobic power. The association between aerobic power and cognitive domains was inconsistent between genders and groups studied. More comparative ethnic/racial studies are needed to determine potential lifestyle factors related to cognitive decline in the elderly living in different societies.Universidad de Costa Rica/[838-B4-364]/UCR/Costa RicaNational Institutes of Health/[1R21TW009665–01]/NIH/Estados UnidosNational Institutes of Health/[R01 AG034614]/NIH/Estados UnidosNational Institutes of Health/[UL1 TR000001]/NIH/Estados UnidosNational Institutes of Health/[KL2 TR000119]/NIH/Estados UnidosNational Institutes of Health/[P30 AG035982]/NIH/Estados UnidosNational Institutes of Health/[K01HD067318]/NIH/Estados UnidosUCR::Vicerrectoría de Investigación::Unidades de Investigación::Ciencias Sociales::Centro de Investigación en Ciencias del Movimiento Humano (CIMOHU)UCR::Vicerrectoría de Investigación::Unidades de Investigación::Ciencias Sociales::Instituto de Investigaciones Psicológicas (IIP
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