5 research outputs found
Carbon film deposition on polyethylene terephtalate by pulsed-plasma technology
No full textElastic amorphous carbon films were deposited by continuous and pulsed-plasma sputtering on polyethylene terephtalate (PET) for gas barrier applications. A study was done of the influence of the plasma parameters on the morphological, mechanical, structural properties of the films. Graphite was used as the sputtering target either in argon-hydrogen RF plasmas. In the pulsed mode operation (on/off), pulse frequencies within the (1-100) kHz range were applied. Pulsing resulted in an enhanced deposition rate and in changes in the ion population composition of the plasma, namely an increase of the hydrogenic ion proportion with the low frequencies. This influenced both the elasticity of the films and the disorder in the atomic structure. Correlations between the plasma process parameters and the permeation properties of the films to He were also mad
Production and characterization of thin a-C:(H) films for gas permeation barrier functionality against He, CO2, N2, O2 and H2O
No full textThis work reports on (i) the gas barrier properties of a-C:H films rf-sputtered in Ar–H2 plasmas from a graphite target on polyethylene terephthalate (PET)and (ii) the influence of the film chemical structure and defect properties on the gas permeability. The intrinsic permeabilities of the films to He, CO2,O2, N2 gases and H2O vapour were determined and found to be orders of magnitude lower than that of the bare PET. Indirect evidence was given to a solubility–diffusion process as the more probable permeation mechanism, over a gas flow through microdefects or gas transport through nanodefects by a Knudsen diffusion mechanism. The barrier capability of the films was found to scale as the gas molecular diameter within the He, CO2, O2 and N2 series, and inversely with the gas critical temperature for the CO2, O2, N2 and H2O series. A correlation between the film Urbach energy, Eu, and the gas permeability was established, except for H2O. Such findings further favour a bulk diffusion contributing mechanism to permeation over the gas state transport. Conversely, this Eu-permeability relation shed more light on the origin of the valence band tailing of the amorphous carbon electron structure
Dosing Regimen for Cefotaxime Should Be Adapted to the Stage of Renal Dysfunction in Critically Ill Adult Patients—A Retrospective Study
No full textCefotaxime administration is recommended in doses of 3–12 g/day in adults with a Glomerular Filtration Rate (GFR) > 5 mL/min. This study aimed to assess the impact of renal function and obesity on cefotaxime concentrations in intensive care unit (ICU) patients. A retrospective cohort study was conducted on consecutive ICU patients receiving continuous cefotaxime infusion between 2020 and 2022 [IRBN992021/CHUSTE]. Doses were not constant; consequently, a concentration-to-dose ratio (C/D) was considered. Statistical analysis was performed to assess the relationship between cefotaxime concentrations, renal function, and obesity. A total of 70 patients, median age 61 years, were included, with no significant difference in cefotaxime concentrations between obese and non-obese patients. However, concentrations varied significantly by GFR, with underdosing prevalent in patients with normal to increased renal function and overdosing in those with severely impaired renal function. Adjustment of cefotaxime dosing according to GFR was associated with improved target attainment. Cefotaxime dosing in critically ill patients should consider renal function, with higher initial doses required in patients with normal to increased GFR and lower doses in those with severely impaired renal function. Therapeutic drug monitoring may aid in optimising dosing regimens. Prospective studies are warranted to validate these findings and inform clinical practice
Additive effects of high growth rate and low transpiration rate drive differences in whole plant transpiration efficiency among black poplar genotypes
No full textPoplar plantations, widely used for the production of woody biomass, might be at high risk from the climate change-induced increase in the frequency of drought periods. Therefore, selecting improved genotypes, which are highly productive but with a high water use efficiency (WUE), is becoming a major target. The use of automated weighing systems in controlled environments facilitates the estimation of cumulated water loss and whole plant transpiration efficiency (TE). Differences in TE and leaf level intrinsic WUE as well as the contribution of underlying ecophysiological traits were determined in three contrasting P. nigra genotypes. Strong differences in TE among the selected genotypes were congruent with differences in leaf level intrinsic WUE. Our data show that a high total leaf area was overcompensated by a low per leaf area transpiration rate, leading to higher TE in highly productive genotypes originating from cool locations. Nocturnal water loss was relatively low but contributed to variations in TE among genotypes. In response to drought, leaf level WUE increased but not TE, suggesting that carbon losses due to whole plant respiration could offset the drought-induced increase in intrinsic WUE.</p
Physiological response of lemon (Citrus aurantiifolia (Christm.) Swingle) to water stress.
No full textIlustraciones, tablasEl trabajo consistió en evaluar la respuesta de limón sutil, al estrés hídrico, la investigación se llevó a cabo en el sitio Maconta perteneciente a la parroquia Colon cantón Portoviejo de la Provincia de Manabí, la finca tiene como nombre “San Nicolás”, es un huerto comercial de 15 años de edad, geográficamente ubicado a 10º082’85’’ de latitud Sur y 80º040’52’’ de latitud Oeste, con una altitud de 40 msnm. Se utilizó como material vegetal árboles de limón sutil [Citrus aurantiifolia (Christm.) (Swingle)] injertados sobre patrón Cleopatra, la distancia de siembra en la plantación es de 6 x 6 en condiciones de campo abierto. Las condiciones climáticas fluctuantes en la zona de estudio reportadas durante la evaluación fueron de, 26,8°C, con humedad relativa de 74,81%. Las evaluaciones se realizaron en dos períodos, uno seco (agosto, septiembre, octubre, noviembre y diciembre) y otro lluvioso (enero, febrero, marzo, abril y mayo). Para fines de evaluación se utilizó un Diseño de Bloques Completo al Azar (BCA) conformado por 5 tratamientos en el que se incluye el control (riego del agricultor) y 6 repeticiones, los tratamientos en función a la demanda atmosférica del cultivo establecidos de la siguiente manera: 0,3; 0,5; 0,7 y 0,9 ET0 más el control.
Se observó un crecimiento precoz a cosecha, con niveles de humedad de 29,17% acumulado en el tratamiento 0,3 ET0, sin alcanzar crecimientos favorables ni rendimientos satisfactorios, pues estos se lograron con una ET0 de 0,5 que obtuvo un de 34 %, este mismo tratamiento resulto ser similar estadísticamente (P 0.05) al control, quien presentó las mayores tasas de asimilación de CO2, así como también mayores tasas de fotosíntesis (A), conductancia estomática (gs) y altas tasas de transpiración (T), el tratamiento control gozó de una frecuencia de riego de cada 8 días, es decir, que contaba con agua a disposición en el suelo. En condiciones de época lluviosa la cosecha de limón fue más temprana y sus rendimientos más bajos, sin embargo, mayor crecimiento del fruto con el tratamiento 0,3 ET0, este mismo en época seca estaba sometido a restricciones hídricas, entonces, este crecimiento se explicaría como una compensación del fruto; por otro lado, el tratamiento con mayor en época lluviosa que fue el de 0,9 ET0, obtuvo los rendimientos más bajos de la época lluviosa; los resultados permiten deducir que el cultivo de limón sutil es susceptible a excesos de humedad en el suelo, esto limita su crecimiento afectando directamente al rendimiento del limón (Texto tomado de la fuente).The research was carried out in the Maconta site belonging to the parish Colon canton Portoviejo of the Province of Manabí, the farm is called "San Nicolás", it is a commercial orchard of 15 years old, geographically located at 10º082'85'' South latitude and 80º040'52'' West latitude, with an altitude of 40 masl. Subtle lemon [Citrus aurantiifolia (Christm.) (Swingle)] trees grafted on Cleopatra rootstock were used as planting material, the planting distance in the plantation is 6 x 6 in open field conditions.
The fluctuating climatic conditions in the study area reported during the evaluation were 26.8°C, with a relative humidity of 74.81%. The evaluations were carried out in two periods, one dry (August, September, October, November and December) and one rainy (January, February, March, April and May). For evaluation purposes, a Randomised Complete Block Design (RCBD) was used, consisting of 5 treatments including the control (farmer's irrigation) and 6 replicates, the treatments according to the atmospheric demand of the crop established as follows: 0.3, 0.5, 0.7 and 0.9 ET0 plus the control.
An early growth at harvest was observed, with humidity levels of 29.17% accumulated in the 0.3 ET0 treatment, without reaching favourable growth or satisfactory yields, as these were achieved with an ET0 of 0.5 that obtained a 34%. 05) to the control, which presented the highest rates of CO2 assimilation, as well as higher rates of photosynthesis (A), stomatal conductance (gs) and high rates of transpiration (T), the control treatment had an irrigation frequency of every 8 days, that is to say, it had water available in the soil. In rainy season conditions the lemon harvest was earlier and yields were lower, however, greater fruit growth with the 0.3 ET0 treatment, which in the dry season was subject to water restrictions, then, this growth could be explained as a compensation of the fruit; On the other hand, the treatment with the highest in the rainy season, which was 0.9 ET0, obtained the lowest yields in the rainy season; the results allow us to deduce that the subtle lemon crop is susceptible to excess moisture in the soil, which limits its growth, directly affecting the lemon yield.DoctoradoDoctor en Ciencias AgrariasSe utilizó como material vegetal árboles de limón sutil [Citrus aurantiifolia (Christm.) (Swingle)] injertados sobre patrón Cleopatra, la
distancia de siembra en la plantación es de 6 x 6 en condiciones de campo abierto. Para fines de evaluación se utilizó un
Diseño de Bloques Completo al Azar (BCA) conformado por 5 tratamientos en el que se
incluye el control (riego del agricultor) y 6 repeticiones, los tratamientos en función a la
demanda atmosférica del cultivo establecidos de la siguiente manera: 0,3; 0,5; 0,7 y 0,9
ET0 más el control
