Carbon plays a major role in physical and biogeochemical processes in the atmosphere, the biosphere, and the ocean. CO2 and CH4 are two of the most common carbon-containing compounds in the atmosphere, also recognized as major greenhouse gases. The exchange of CO2 and CH4 between the ocean and the atmosphere is an essential part of the global carbon cycle. The exchange is controlled by the air–sea concentration gradient and by the efficiency of the transfer processes. The lack of knowledge about the forcing mechanisms affecting the exchange of these climate-relevant gases is a major source of uncertainty in the estimation of the global oceanic contributions. Quantifying and understanding the air–sea exchange processes is essential to constrain the estimates and to improve our knowledge about the current and future climate. In this thesis, the mechanisms controlling the air–sea gas exchange in the Baltic Sea are investigated. The viability of micrometeorological techniques for CH4 monitoring in a coastal environment is evaluated. One year of semi-continuous measurements of air–sea CH4 fluxes using eddy covariance measurements suggests that the method is useful for CH4 flux estimations in marine environments. The measurements allow long-term monitoring at high frequency rates, thus, capturing the temporal variability of the flux. The region off Gotland is a net source of CH4, with both the air–sea concentration gradient and the wind as controlling mechanisms. A sensitivity analysis of the gas transfer velocity is performed to evaluate the effect of the forcing mechanisms controlling the air–sea CO2 exchange in the Baltic Sea. This analysis shows that the spatio-temporal variability of CO2 fluxes is strongly modulated by water-side convection, precipitation, and surfactants. The effect of these factors is relevant both at regional and global scales, as they are not included in the current budget estimates.

Ozone is known to be the most widespread phytotoxic air pollutant. Ozone causes visible injury, reductions in photosynthesis, growth, and yield. Plant response to ozone may vary with species, varieties, and physiological age. Comparison between sensitive and tolerant cultivars has a key role in assessing ozone damage, investigating the sites of cellular injury, and identifying ozone tolerance mechanism. The objectives of this study were to investigate the effects of high ozone concentration (200 ppb) as well as ambient ozone concentrations (under field conditions) on net CO2 assimilation and PSII function in plants with different sensitivities to ozone. Two species of plants, tobacco (Nicotiana tabacum L.) and black cherry (Prunus serotina) were studied. Gas exchange analysis and chlorophyll fluorometry were utilized to characterize physiological function. Two tobacco cultivars, Bel-B and Bel-W3, tolerant and sensitive to ozone, respectively, were grown in a greenhouse supplied with charcoal filtered air and then exposed to 200 ppb ozone for 4hr. Effects on chlorophyll fluorescence, net photosynthesis, and stomatal conductance are described. Quantum yield was calculated from chlorophyll fluorescence and the initial slope of the assimilation-light curve measured by the gas exchange method. Only the sensitive cultivar, Bel-W3, developed visible injury symptoms involving up to 50% of the 5th leaf. The maximum net photosynthetic rate of ozone-treated plants of the tolerant cultivar was reduced 40% compared to control plants immediately after ozone fumigation; however, photosynthesis recovered by 24 hr post fumigation and remained at the same level as control plants. In the sensitive cultivar, on the other hand, ozone exposure reduced maximum net photosynthesis up to 50%, with no recovery, apparently causing permanent damage to the photosystem. Reductions in apparent quantum efficiency, calculated from the assimilation-light curve, differed between cultivars. Bel-B showed an immediate depression of 14% compared to controls, whereas Bel-W3 showed a 27% decline. Electron transport rate (ETR), at saturating light intensity, decreased 58% and 80% immediately after ozone treatment in Bel-B and Bel-W3, respectively. Quantum yield decreased 28% and 36% in Bel-B and Bel-W3, respectively. It can be concluded that ozone caused a greater relative decrease in linear electron transport than maximum net photosynthesis, suggesting greater damage to PSII than the carbon reduction cycle. Two different sensitivity classes of black cherry, tolerant and sensitive, growing under natural environmental conditions in Giles County, VA were assessed for physiological responses to ambient ozone concentrations. Additional measurements were made at two other sites near Blacksburg. Leaf gas exchange rates and visible foliar injury were determined monthly during the growing seasons of 2000, 2001, and 2002 to characterize the relationship of injury to altered photosynthetic function. Ambient ozone levels were sufficient to induce visible symptoms which were highly correlated with a reduction in PnMAX (maximum net photosynthetic rate under saturating light conditions) and à CO2 (quantum yield for carbon reduction) only in sensitive black cherry. Electron transport rate (ETR) and quantum yield of PSII (à PSII) were also reduced in sensitive black cherry. Maximum photochemical efficiency (Fv/Fm) in sensitive trees was severely damaged by ambient ozone. There were positive correlations between increasing cumulative ozone concentration and substantial reductions in PnMAX and in à CO2 of sensitive trees compared to tolerant trees. There was a negative correlation between chlorophyll content and percent leaf injury in sensitive black cherry / Ph. D.

The objective of this research was to determine how genetics and nutrient availability influence C cycling in intensively managed southern pine forests. This work consisted of a two year field and a complimentary one year greenhouse study each split into above- and below-ground pools and fluxes. Both the greenhouse and field experiment showed differences between contrasting genotypes in gas exchange parameters and C partitioning patterns, but genetic by nutrient availability interactions were only observed in the field. In the field study, some genotypes were better able to tolerate nutrient limitations due to more favorable canopy architecture and lower N demand. Our results clearly show that contrasting ideotypes have the potential to respond differently to differences in nutrient availability in terms of biomass partitioning, leaf physiology, and leaf biochemistry (Chapter 3). Both experiments showed short-term improvements to soil physical and chemical properties, which have been shown to correlate with higher site quality. In both the greenhouse and field experiment, we concluded that increased C loss by way of total soil CO₂ efflux (FS) made up only a small percent total C incorporated as LR. Short-term results led us to conclude that combining LR treatments and planting of genotypes with low nutrient demand or high nutrient use efficiency may increase soil organic matter (SOM) while avoiding loss of stem volume from nutrient immobilization. Data from our field study showed a strong genotype by soil amendment interaction for FS over all sampling dates with the relative importance of contributing factors (heterotrophic or root respiration) also changing (Chapter 5). Overall, logging residue incorporation increased total system C gain per ha more than did fertilization alone, but there were differences between genotypes planted (Chapter 6). Data from the field experiment show that although LR incorporation did not decrease overall net primary productivity, it did decrease biomass partitioning to merchantable products (main stem) depending on genotype. These data underline the importance of matching appropriate genotypes to specific site conditions and silvicultural prescriptions. / Ph. D.

Spatial and temporal variation in foliar gas exchange on both a diurnal and seasonal scale was examined in 15-year-old fertilized and non-fertilized loblolly pine in the upper and lower thirds of crowns in stands located in the North Carolina sandhills. Photosynthesis rates between control and fertilized stands for both seasonal and diurnal measurement periods were different during only three months. Photosynthesis rates were consistently greater in the upper third of the crown compared to the lower third. Seasonal trends in both conductance and transpiration closely resembled trends found in seasonal photosynthesis. Foliar nitrogen concentrations were greater in fertilized stands for all months sampled. However, nitrogen content generally did not correlate with photosynthesis rates. Mean monthly water use efficiencies were significantly higher in fertilized stands during two months and were usually greater in upper crown foliage. Common empirical gas exchange models reveal that light and vapor pressure deficit (VPD) explain a majority of the variation observed in photosynthesis and transpiration, respectively. Conductance was not modeled since environmental variation did not adequately explain conductance patterns. Predicted light response curves reveal that upper crown foliage has higher maximum photosynthesis rates, respiration rates, light compensation points, and lower initial quantum yield compared to lower crown foliage. Models predict that foliage from fertilized stands is more sensitive to VPD and light during the growing season. Transpiration models predict highly variable responses to VPD depending on the treatment combination and season. Model R-square and predicted gas exchange values suggest that seasonal acclimation occurred. / Master of Science

Tesis por compendio / [EN] For many years energy needs of ruminants have tried to be known to formulate rations adjusted, but it has been found that there are a variety of factors that affect them. Therefore, lots of studies are needed for evaluating the effect of these factors. Consequently, the main objective of this Thesis was to design and validate a respirometry system based on indirect calorimetry, which would allow assessing energy needs of small ruminants accurately. It was intended from the beginning it was a mobile system and of relatively low cost. Furthermore, a methane gas analyzer was incorporated to this system, which allowed the measurement of emissions of this greenhouse gas and quantification of energy losses in the form of methane. Initially the system had connected a mask, which was placed on the animal's face. A sample of exhaled gas was stored in a gas collection bag which was connected to the analyzer, and it measured the concentration of O2, CO2 and CH4 from the air. The proper functioning of the system was checked by a pilot experiment with dry Murciano-Granadina breed goats fed at maintenance level. Later this system was improved. Some of the most important changes were the replacement of the mask by a head hood in which the animal introduced the whole head, and the development of software that recorded and kept automatically concentrations of O2, CO2 and CH4 in exhaled air. This improvement allowed gas measurements during longer periods of time and recording more data. These changes were also validated through a pilot test with dry Manchega breed sheep. Subsequently, three experiments were performed. One of them with dry Guirra ewes and the other two with Murciano-Granadina goats during mid lactation. Diets were mixed rations that differed in the inclusion of cereal or fibrous by-products. In these experiments the effect of diet was studied on digestibility, energy balance and carbon-nitrogen, oxidation of nutrients, rumen parameters and methane production; in the case of lactating goats, also on milk performance. The determination of the calibration factor for O2 (1.005 ± 0.0101) confirmed the proper functioning of equipment. Moreover, small differences between the heat production obtained by indirect calorimetry and the carbon-nitrogen balance (2% in sheep and 1% in goats) demonstrated that this system allows determining the heat production of the animals reliably and accurately. In the experiments of this Thesis have been estimated maintenance energy needs of two Spanish native sheep breeds, such as the sheep from the Guirra and Manchega breeds; net maintenance requirements were 270 kJ/kg BW0.75, on average. In the case of Murciano-Granadina breed goats, in the middle of lactation, the average utilization efficiency of metabolizable energy for lactation was 0.61. / [ES] Desde hace años se ha tratado de conocer las necesidades energéticas de los rumiantes con el fin de formular raciones ajustadas, pero se ha comprobado que hay una gran variedad de factores que les afectan; por ello son necesarios estudios que evalúen el efecto de estos factores. Como consecuencia, el principal objetivo de esta tesis fue diseñar y validar un equipo de respirometría, basado en calorimetría indirecta, que permitiese evaluar las necesidades en energía de pequeños rumiantes de forma precisa. Se pretendió desde el inicio que fuese un sistema móvil y de relativo bajo coste. Además, a este sistema también se le incorporó un analizador de gas metano, que permitía la medición de las emisiones de este gas de efecto invernadero y la cuantificación de las pérdidas energéticas en forma de metano. Inicialmente el equipo tenía conectada una máscara que se colocaba en la cara del animal. Una muestra del gas espirado era almacenada en una bolsa de recogida de gases que era conectada al analizador, el cual medía la concentración de O2, CO2 y CH4 del aire. Se comprobó el correcto funcionamiento del sistema mediante una prueba piloto con cabras de raza Murciano-Granadina secas, alimentadas a nivel de mantenimiento. Posteriormente este sistema fue mejorado. Algunos de los cambios más importantes fueron la sustitución de la máscara por una urna en la que el animal introducía la cabeza entera, y el desarrollo de un software que registraba y guardaba de forma automática las concentraciones de O2, CO2 y CH4 del aire espirado. Esta mejora permitía medidas de gases durante periodos de tiempo más largos y el registro de muchos más datos. Estas modificaciones también fueron validadas mediante una prueba piloto con ovejas de raza Manchega secas. Posteriormente se realizaron tres experimentos. Uno de ellos con ovejas de raza Guirra secas y los otros dos con cabras Murciano-Granadinas en mitad de lactación. Las dietas fueron raciones mixtas que diferían en la inclusión de cereal o subproductos fibrosos. En estos experimentos se estudió el efecto de la dieta sobre la digestibilidad, balances de energía y carbono-nitrógeno, oxidación de los nutrientes, parámetros del rumen y producción de metano; en el caso de las cabras en lactación, también sobre los rendimientos productivos. La determinación del factor de calibrado para el O2 (1,005 ± 0,0101) confirmó el buen funcionamiento del equipo. Por otro lado, las pequeñas diferencias entre la producción de calor obtenida mediante calorimetría indirecta y el balance de carbono-nitrógeno (2% en ovejas y 1% en cabras) demostraron que este sistema permite determinar la producción de calor de los animales de forma fiable y precisa. En los trabajos de esta Tesis se han estimado las necesidades energéticas de mantenimiento en dos razas de ovejas autóctonas españolas, como son las razas Guirra y Manchega; las necesidades netas de mantenimiento fueron 270 kJ/kg PV0,75, de media. En el caso del ganado caprino de raza Murciano-Granadina, en mitad de lactación, la eficacia media de utilización de la energía metabolizable para la lactación fue de 0,61. / [CA] Des de fa anys s'ha tractat de conèixer les necessitats energètiques dels remugants a fi de formular racions ajustades, però s'ha comprovat que hi ha una gran varietat de factors que els afecten; per això són necessaris estudis que avaluen l'efecte d'estos factors. Com a conseqüència, el principal objectiu d'aquesta Tesi va ser dissenyar i validar un equip de respirometría, basat en calorimetria indirecta, que permetera avaluar les necessitats en energia de menuts remugants de forma precisa. Es va pretendre des de l'inici que fóra un sistema mòbil i de relatiu baix cost. A més, a este sistema també se li va incorporar un analitzador de gas metà, que permetia el mesurament de les emissions d'este gas d'efecte hivernacle i la quantificació de les pèrdues energètiques en forma de metà. Inicialment l'equip tenia connectada una màscara que es col·locava en la cara de l'animal. Una mostra del gas expirat era emmagatzemada en una bossa d'arreplega de gasos que era connectada a l'analitzador, el qual mesurava la concentració d'O2, CO2 i CH4 de l'aire. Es va comprovar el funcionament correcte del sistema per mitjà d'una prova pilot amb cabres de raça Murciano-Granadina seques, alimentades a nivell de manteniment. Posteriorment este sistema va ser millorat. Alguns dels canvis més importants van ser la substitució de la màscara per una urna en què l'animal introduïa el cap sencera, i el desenrotllament d'un programari que registrava i guardava de forma automàtica les concentracions d'O2, CO2 i CH4 de l'aire expirat. Esta millora permetia mesures de gasos durant períodes de temps més llargs i el registre de moltes més dades. Estes modificacions també van ser validades per mitjà d'una prova pilot amb ovelles de raça Manxega seques. Després es van realitzar tres experiments. Un d'ells amb ovelles de raça Guirra seques i els altres dos amb cabres Murciano-Granadinas en mitat de lactació. Les dietes van ser racions mixtes que diferien en la inclusió de cereal o subproductes fibrosos. En estos experiments es va estudiar l'efecte de la dieta sobre la digestibilitat, balanços d'energia i carboni-nitrogen, oxidació dels nutrients, paràmetres del rumen i producció de metà; en el cas de les cabres en lactació, també sobre els rendiments productius. La determinació del factor de calibrat per a l'O2 (1,005 ± 0,0101) va confirmar el bon funcionament de l'equip. D'altra banda, les xicotetes diferències entre la producció de calor obtinguda per mitjà de calorimetria indirecta i el balanç de carboni-nitrogen (2% en ovelles i 1% en cabres) van demostrar que este sistema permet determinar la producció de calor dels animals de forma fiable i precisa. En els treballs d'esta Tesi s'han estimat les necessitats energètiques de manteniment en dos races d'ovelles autòctones espanyoles, com són les races Guirra i Manxega; les necessitats netes de manteniment van ser 270 kJ/kg PV0,75, de mitja. En el cas del bestiar caprí de raça Murciano-Granadina, en mitat de lactació, l'eficàcia mitjana d'utilització de l'energia metabolitzable per a la lactació va ser de 0,61. / López Luján, MDC. (2015). Development of a mobile open-circuit system based on indirect calorimetry for energetic metabolism studies in small ruminants [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/50430 / Compendio

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The alm of the work was to evaluate the impact of facilitation of physiologic coordination of respiratory and postural functions of diaphragm by Vojta-therapy on gas exchange. This thesis summarizes available knowledge about anatomical background of diaphragm functions, together with other trunk muscles known as deep stabilizing system. Moreover, it describes coordination of breathing and postural functions. We tried to objectify impact of diaphragm activation on gas exchange in healthy adults. Two following spiroergometries were compared aťt:er Vojta-therapy stimulation and with placebo. We evaluated minute ventilation, breath frequency, tidal volume, oxygen consumption, rate oť elimination of carbon dioxide and respiratory quotient. There were no statistical differences between placebo and Vojta- therapy group at exercise intensity levels 1 W /kg, 2 W /kg and in maximal exercise. Powered by TCPDF (www.tcpdf.org)

L‘arsenic et l‘antimoine bien que n‘étant pas recensés parmi les polluants majeurs de l‘environnement sont souvent retrouvés associés à d‘autres contaminants. En France, et plus particulièrement dans la région Auvergne, de nombreux sites miniers où s‘effectuait l‘extraction de l‘antimoine sont désormais à l‘abandon. Pouvant présenter des risques pour les populations avoisinantes, leur réhabilitation est donc une mission d‘intérêt public. L‘idée de ce travail de doctorat est de tester l‘effet d‘un catalyseur : le ver de terre sur l‘efficacité des processus de phytoremédiation. En tant qu‘« ingénieurs du sol », ils sont à la base des processus de pédogénèse et peuvent donc assurer la restructuration du sol. De plus, de nombreuses études ont montré leurs effets positifs sur la production de biomasse végétale. Cependant, les mécanismes moléculaires responsables de cette acroissement de production demeurent méconnus. Un système expérimental novateur, jamais utilisé en Ecologie des Sols et couplant la plante modèle Arabidopsis thaliana (L.) Heynh et Aporrectodea caliginosa (Savigny), un ver de terre endogé commun des régions tempérées, a été mis en place afin de 1) identifier les principales voies métaboliques modifiées en réponse aux vers de terre et pouvant expliquer leurs effets positifs sur la croissance et le développement des végétaux, 2) étudier la nutrition minérale en fer et en phosphate, notamment au niveau des variations d‘expression des transporteurs de ces deux éléments, 3) tester ce système pour la phytoextraction de sédiments, issus d‘un ancien site minier, contaminés à l‘arsenic et à l‘antimoine. Les résultats montrent que l‘amélioration des processus de minéralisation est déterminante dans l‘accroissement de la biomasse d‘Arabidopsis thaliana qui se traduit aussi par une élévation des teneurs en azote dans les parties aériennes. Cependant, la présence de phytohormones, produites par des bactéries activées par leur transit dans le ver de terre semble également impliquée dans le renforcement de l‘absorption d‘azote. A l‘échelle moléculaire, les vers entraînent une surexpression du gène HBT, impliqué dans la division cellulaire et semblent diminuer le stress oxydant puisque la quantité de transcrits SOD Cu/Zn diminue. Les résultats montrent de plus que les vers de terre augmentent de façon significative l‘absorption et l‘accumulation de fer, de phosphate et d‘autres minéraux essentiels à la croissance du végétal. Moléculairement, l‘augmentation de l‘absorption des nutriments se traduit par une augmentation de la transcription de certains gènes codant des transporteurs tels que PHT1.3, qui est un transporteur de haute affinité pour le phosphate. Une augmentation de la transcription et également de l‘activité de la protéine FRO2, qui est à l‘origine de la chélation et de la réduction du fer a été observée. Dans les feuilles, les vers de terre induisent de manière systémique la surexpression d‘un transporteur de phosphate localisé dans les chloroplastes, PHT2.1 et la surexpression de transporteurs du fer appartenant à la famille des NRAMPs, notamment NRAMP1,2 et 6. Dans le contexte d‘une problématique de phytoremédiation, l‘effet des vers de terre sur la capacité de phytoextraction d‘Arabidopsis a été testé et, il ressort clairement de cette étude que les vers de terre permettent une meilleure absorption d‘antimoine et d‘arsenic. Cependant, ces deux métalloïdes tendent à rester dans les racines et ne sont que faiblement transferrés vers les parties aériennes. Cette formidable augmentation des concentrations en polluants dans les racines entraîne un retard de croissance considérable et affecte, dans une moindre mesure cependant, l‘activité photosynthétique et les échanges gazeux d‘Arabidopsis. Ainsi, ce travail de thèse a donc tout d‘abord démontré la sensibilité aux vers de terre de la plante modèle Arabidopsis thaliana. Ce système expérimental novateur offre de nouvelles possibilités de recherches dans le domaine des études des interactions entre les vers de terre et les plantes, notamment en raison de la grande diversité de mutants d‘Arabidopsis. De plus, ce travail a également permis de démontrer le rôle crucial de catalyseur que peuvent jouer les vers de terre en vue d‘optimisation des processus de phytoextraction. / Arsenic and antimony do not belong to the major pollutants of the environment but are offen foun associated with other contaminants. In France, more specifically in Auvergne region, a large number of old mining site where antimony was extracted are currently abandoned. As they present several risks for the neighbourhood populations, their habilitaion appears to be essential. The main idea if this PhD work is to test a catalysor: the earthworms in order to increase phytoremédiation efficacity. As ―soils ingeniors‖, they are involved in pedogenesis process and can lead to soil reorganization. Moreover, several studies have presented their positive effects on plant biomass. Nevertheless, the molecular mechanisms responsible of this production enhancement remain still unknown. An innovative experimental system, never used in Soil Ecology, using the model plant Arabidopsis thaliana (L.) Heynh and the endogeic temperate earthworms Aporrectodea caliginosa (Savigny) has been set up. This research work has three goals. First, identify the main metabolic pathway affected by earthworm presence and able to explain their positive effects on plant growth and development. Then, this research work focused on phosphorus and iron nutrition particularly by studing the molecular variation of several transporters of these elements. Lastly this system has been tested for phytoextraction of wastes from an old mining site polluted by arsenic and antimony. In the first part of this study, the mineralization process improvement appears to be a determining factor in Arabidopsis growth enhancement due to nitrogen increase in the shoots. Nevertheless, phytohormones producted by bacteria activated during their transit into earthworm gut seem to be involved in nitrate assimilation. At the molecular scale, earthworms enhance an overaccumulation of HBT transcripts involved in cell division and they seem to decrease the oxidative stress as SOD transcripts are underexpressed. The second part of this study focused on mineral nutrition. Results show that earthworms enhance significantly the uptake and accumulation of phosphorus, iron and other growth essential minerals. At the molecular scale, the nutrient uptake increase result in an increase of several transporters such as Pht1.3, which is a high affinity phosphate transporter and also an overexpression and an increase in enzymatic activity of the ferric chelate reductase protein FRO2. In the leaves, this experiment also show the overaccumulation of a phosphate chloroplastic transporter Pht2.1 and over expression of iron transporter belonging to the NRAMPS family, especially NRAMP1,2 and 6. Then, this system has been transposed to the phytoremédiation and earthworm effects have been tested on the phytoextraction properties of Arabidopsis. Earthworms allow a better uptake of arsenic and antimony. Nevertheless the pollutants tend to remain in the root system and are not translocated in the aerial part. This incredible increase in pollutant tissue concentration leads to a growth and development delay and affect the Arabidopsis photosynthetic activity. To conclude, this PhD work has first shown earthworm sensitivity of Arabidopsis. This innovative system offers new investigation possibilities in the interaction between earthworms and plant area, especially due to the large range of Arabidopsis mutants. Moreover, this work has also demonstrated the key role as catalysor that can play earthworms in order to optimize phytoremédiation process.

A cana-de-açúcar apresenta acentuada variação genotípica relacionada à eficiência de uso dos nutrientes, sendo que a abordagem desse assunto em pesquisas científicas prioriza os estudos relacionados ao nitrogênio (N) e fósforo (P). Porém, devido a essencialidade do potássio (K) como nutriente pela função exercida nas relações hídricas das plantas e sua importância na economia brasileira, pesquisas relacionadas à eficiência de uso de K podem auxiliar no desenvolvimento de genótipos mais eficientes, com implicações diretas no processo de eficiência de uso de água. No primeiro experimento (Experimento I), objetivou-se avaliar as mudanças morfológicas e fisiológicas promovidas pela redução do suprimento de K, em dois genótipos de cana-de-açúcar (SP90-3414 e SP83-2847), por meio da quantificação da área foliar; aspectos morfológicos do sistema radicular (comprimento total e superfície total de raízes); produção de biomassa de raízes e parte aérea; concentração e acúmulo de K nos tecidos vegetais; partição de fotoassimilados (porcentagem de açúcares solúveis totais [AST] e redutores [AR]); atividade da enzima redutase do nitrato (RNO3-); potencial da água na folha (?a) e parâmetros de trocas gasosas (taxa de assimilação de CO2 [A], condutância estomática [gs] e transpiração [E]). As concentrações de K empregadas na solução nutritiva foram de 1 e 6 mmol L-1, distribuídas conforme delineamento experimental de blocos completos ao acaso, utilizando-se esquema fatorial 2 x 2 (duas doses de K x dois genótipos de cana-de-açúcar), com cinco repetições. As doses promoveram diferenças quanto à absorção e uso do K pelos cultivares, promovendo alterações significativas no acúmulo desse elemento nos tecidos vegetais, na quantidade de açúcares solúveis totais e redutores nos tecidos, nos parâmetros morfológicos e produtivos da parte aérea e do sistema radicular, bem como nos atributos fisiológicos da fotossíntese e da redução do nitrato. No segundo experimento (Experimento II) objetivou-se avaliar a influência do déficit hídrico nos parâmetros morfológicos e fisiológicos das plantas, bem como estudar o comportamento desses parâmetros em função do aumento da concentração de K disponível no substrato. As análises tiveram como objetivo avaliar as relações hídricas das plantas e a interferência dessa condição hídrica nos processos de trocas gasosas, bem como relacionar os parâmetros de eficiência de uso de K (KUtE) com a eficiência de uso de água (EUA). O experimento foi conduzido em vasos contendo 8 dm3 de terra, o delineamento experimental também foi o de blocos completos ao acaso, utilizando esquema fatorial 2 x 2 x 2 (duas doses de K x dois regimes hídricos x dois cultivares), sendo utilizadas as doses de K de 1 e 6 mmolc dm-3 de terra, os regimes hídrico de 70% e 20% da capacidade máxima de armazenamento de água do solo e os genótipos SP90-3414 (suscetível) e SP83-2847 (tolerante ao estresse hídrico). Constataram-se incrementos nos parâmetros hídricos e de trocas gasosas dos cultivares desenvolvidos com adequado suprimento de K e submetidos ao déficit hídrico, indicando haver relação positiva entre a adubação potássica e a resistência das plantas de cana-de-açúcar submetidas a condição hídrica adversa. Ou seja, a eficiência de uso da água (EUA) no genótipo tolerante (SP83-2847) pode ser resultado direto da eficiência de uso de K (KUtE) / Sugarcane has marked genotypic variation related to nutrient use efficiency, which in turn the approach of this subject in scientific research prioritizes studies related to nitrogen (N) and phosphorus (P), but due to the essentiality of potassium (K) as a nutrient, and its importance in the Brazilian economy, researches related to K use efficiency can help the development of efficient genotypes, which, because the K water relation functions in plants may have a direct relation in the water use efficiency. In the first experiment were evaluate the changes in morphological and physiological sugarcane genotypes (SP90-3414 and SP83-2847) promotes by the reduction of K concentration, the parameters were quantifying the leaf area; root system morphology (total length and total surface area of roots); biomass of roots and shoots; K concentration and accumulation in plant tissues; total soluble and reduced sugars percentage; activity of the enzyme nitrate reductase; leaf water potential and gas exchange parameters. The K concentrations used in the nutrient solution were 1 and 6 mmol L-1, distributed as experimental design of randomized complete block design, using a factorial 2 x 2 (two K rates x two sugarcane genotypes), with five replications. The rates caused differences in the K uptake efficiency by cultivars, triggering positive changes in their accumulation in plant tissues and the morphological and physiological parameters. The second experiment were to evaluated the influence of water deficit on morphological and physiological parameters of the plants and to study the behavior of these parameters according to the increase of the available K concentration. The analysis aimed to evaluate the water relations in plants and the water status interference in the gas exchange process, as well as relating the parameters of the K use efficiency with the efficiency of water use. The experiment was conducted in pots containing 8 dm3 of soil, the experiment was also conducted in a randomized block design, using a factorial 2 x 2 x 2 (two K rates x two water regimes x two sugarcane cultivars), and the K rates used was 1 and 6 mmolc dm-3 of soil, water regimes was 70% and 20% of field capacity and the genotypes were the same as the first experiment. The results shows improvements in water and gas exchange parameters of cultivars developed in high-level K and subjected to water deficit, showing a positive relationship between potassium fertilization and sugarcane plant resistance to adverse water condition. On average, the highest water use efficiency (WUE) of SP83-2847 tolerant genotype may result from potassium use ufficiency (KUtE)

Este trabalho apresenta o desenvolvimento de um simulador numérico para o transporte convectivo-reativo, não linear, de oxigênio, em oxigenadores de sangue, compostos por fibras ocas. O modelo computacional possui caráter bi-dimensional e obtém para a condição de regime permanente, a condição de saída do sangue, frente a uma condição de entrada especificada. Os parâmetros de entrada do sangue são: vazão, temperatura, pH, PCO2 , PO2 e concentração de hemoglobina. Já os parâmetros de entrada do gás são, basicamente: vazão, temperatura, umidade relativa, frações molares de oxigênio e gás carbônico. O simulador numérico também contempla a simulação do transporte de gás carbônico, uma vez que a afinidade da oxihemoglobina é afetada pelo pH local do sangue, que depende principalmente do conteúdo local de CO2 no sangue. O simulador baseia-se num coeficiente global de transporte de massa obtido a partir de resultados experimentais em sangue bovino. As equações utilizadas para o transporte de oxigênio e gás carbônico estão parametrizadas em função da temperatura, o que permite simular o desempenho do oxigenador em circulações extracorpóreas tanto em normo como em hipotermia. O modelo computacional foi desenvolvido para a geometria de escoamento de sangue externo a um feixe de fibras, com o gás escoando no interior das mesmas, com uma única passada de ambos os fluidos. O modelo foi aplicado para dois tipos de geometrias: feixe de fibras alinhadas e feixe de fibras em quicôncio. Adicionalmente, avaliou-se a viabilidade da predição do transporte de massa no sangue, calibrando-se o simulador numérico a partir de ensaios em água. Como principais resultados do trabalho desenvolvido, temos: 1) A modelagem utilizada para o transporte convectivo-reativo no sangue mostrou ser adequada para a calibração do simulador numérico desenvolvido. Desta forma, obteve-se uma estimativa precisa dos coeficientes locais de transporte de massa para o oxigênio e o gás carbônico. 2) A obtenção da distribuição de pH, ao longo do oxigenador, demonstrou que valores de pH alcalino elevado são observados no trajeto do sangue, na vizinhança do local de entrada de gás. 3) O simulador numérico obtido pode ser utilizado como uma ferramenta computacional de auxílio no projeto de oxigenadores de sangue. 4) Os testes com água são pouco eficientes na calibração do simulador, uma vez que, para isto, é necessário o conhecimento das difusividades de oxigênio e gás carbônico no sangue, as quais são modificadas pela ocorrência de intensificação. / A numeric simulator was developed to predict the non-linear, convective-reactive, oxygen transport in hollow fibers blood oxygenators. The bidimensional computational model calculates, at the steady state condition, the blood outlet for a specified inlet condition. The blood flow inlet parameters taken into account are: flow, temperature, pH, PCO2 PO2 and hemoglobin concentration. The gas flow inlet parameters are: flow, temperature, relative humidity, molar fractions of oxygen and carbonic gas. The numeric simulator also simulates the CO2 transport, as the oxyhemoglobin affinity is affected by the pH local value, which depends mostly on CO2 local blood content. The simulator is calibrated against experimental data which allows the determination of the global mass transport coefficient for oxygen and CO2. Oxygen and CO2 blood content equations are explicitly temperature dependent to allow the simulation of both normothermic and hypothermic cardiopulmonary bypass. The computational model was tested for in-line and staggered fibers bundles. In addition, it was evaluated the advantages of simulator calibration from water tests. The principal results are: 1) The convective-reactive transport modeling showed to be adequate to the calibration of the numeric simulator. 2) Local values for pH, PCO2 and PO2 were obtained along the blood path. This analysis shows that very alkaline pH values occur at the blood path at the gas inlet side of the fiber bundle. 3) The numeric simulator can be used as a computational tool to support blood oxygenators development. 4) The water tests are not effective in the prediction of blood mass transport once different values for the oxygen and CO2 blood diffusivities were used to correlate blood-water results according to fiber bundle type, which is in agreement with other results, that point out that, at blood, intensification phenomena modifies blood gases diffusivities.