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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
21

Ação de cupins de madeira seca (Cryptotermes brevis) e de solo (Nasutitermes corniger) nas madeiras termorretificadas de Pinus taeda e de Corymbia citriodora / Action of dry wood termite (Cryptotermes brevis) and subterranean termite (Nasutitermes corniger) on the thermorectified wood of Pinus taeda and Corymbia citriodora

Brito, Juliana Pires 27 May 2015 (has links)
A termorretificação ou retificação térmica é uma técnica auxiliar na preservação da madeira, sendo um processo controlado de pirólise, em temperaturas que variam entre 140°C a 220°C. No presente trabalho, foi testada a hipótese de que a termorretificação na temperatura de 200ºC aumenta a resistência da madeira em relação ao ataque de cupins, buscando identificar se tal efeito é resultante da menor disponibilidade de água ou da deposição de substâncias tóxicas ou repelentes formadas durante a degradação térmica. Foi constatado que as alterações provocadas pela termorretificação reduzem a capacidade de adsorção de água pela madeira e, consequentemente, o seu teor de umidade de equilíbrio. As substâncias geradas durante o processo de termorretificação, extraídas em água quente, tem efeito preservativo quando aplicadas à madeira natural, com diferentes resultados entre as espécies florestais. A termorretificação reduziu a capacidade de ação do Cryptotermes brevis, com efeito mais acentuado no Pinus taeda. A remoção dos extrativos da madeira termorretificada, por si só, não implicou no aumento da intensidade da ação dos cupins, o que somente se tornou mais evidente quando aumentou o teor de umidade do material. Em relação ao Nasutitermes corniger, ocorreram diferenças na ação dos cupins em relação ao tipo de oferta de alimento, bem como em relação às espécies de madeira. Para a alimentação forçada, houve acentuado efeito da termorretificação, em ambas as espécies de madeira, tendo ocorrido uma acentuada redução na perda de massa das madeiras quando comparada à madeira original. Constatou-se haver efeito dos extrativos na redução da ação dos cupins de solo, com maior ênfase para a madeira de Pinus taeda. No ensaio de preferência alimentar, nenhum dos tratamentos avaliados foi eficiente para prevenir a degradação pelos cupins, com o Pinus taeda apresentando maior suscetibilidade em comparação com o Corymbia citriodora. Considerando o conjunto dos resultados, conclui-se que a madeira termorretificada é resistente ao ataque de cupins de madeira e essa resistência é decorrente da interação entre a menor higroscopicidade provocada pela modificação química do material e a presença dos extrativos gerados durante o processo de termorretificação; e que o efeito preservativo da termorretificação não é suficiente para indicar o uso da madeira termotratada em contato direto com o solo, devido à suscetibilidade aos cupins subterrâneos. / The thermorectification, a controlled pyrolysis at temperatures ranging between 140°C to 220°C, is considered a technique that could preserve the wood against biological degradation. In this study it was tested the hypothesis that the thermorectification at 200ºC increase the lumber resistance against termite attack, looking to identify if this effect is a result of the reduced available moisture or due the deposition of toxic substances formed during the thermal treatment. It was evidenced that the chemical modifications caused by thermorectification reduced wood sorption capacity and, by consequence, its equilibrium moisture content. The substances formed during the thermal treatment, extracted with hot water, have a preservative effect when applied to natural lumber, with different results between the two wood species. The thermorectification reduced the attack of Cryptotermes brevis and this influence was more effective on Pinus taeda. The removal of extractives from thermotreated wood did not cause an increase in the intensity of termite action, which only became more evident when the lumber moisture content increased. In relation to Nasutitermes corniger, there were differences in the action of termites, depending of the feeding conditions and wood species. In the food choice test, there was an important effect of thermorectifiction in both wood species, reducing the loss of mass due to termite attack when compared to original wood. The extractives also reduced the action of soil termites, with greater emphasis on Pinus taeda lumber. In the no food choice test, no one of the treatments evaluated was enough to prevent the termite action, and it was showed that Pinus taeda wood was more susceptible compared to Corymbia citriodora. Considering all the results, it is possible to conclude that thermorectified lumber is resistant against dry wood termite attack and this resistance is due to interaction between the reduced wood hygroscopicity promoted by the wood chemical changes and the presence of substances generated during the thermal treatment; and the preserving effect of thermorectification is not enough to suggest the use of thermorectified lumber in direct ground contact due its susceptibility to subterranean termite action.
22

Ação de cupins de madeira seca (Cryptotermes brevis) e de solo (Nasutitermes corniger) nas madeiras termorretificadas de Pinus taeda e de Corymbia citriodora / Action of dry wood termite (Cryptotermes brevis) and subterranean termite (Nasutitermes corniger) on the thermorectified wood of Pinus taeda and Corymbia citriodora

Juliana Pires Brito 27 May 2015 (has links)
A termorretificação ou retificação térmica é uma técnica auxiliar na preservação da madeira, sendo um processo controlado de pirólise, em temperaturas que variam entre 140°C a 220°C. No presente trabalho, foi testada a hipótese de que a termorretificação na temperatura de 200ºC aumenta a resistência da madeira em relação ao ataque de cupins, buscando identificar se tal efeito é resultante da menor disponibilidade de água ou da deposição de substâncias tóxicas ou repelentes formadas durante a degradação térmica. Foi constatado que as alterações provocadas pela termorretificação reduzem a capacidade de adsorção de água pela madeira e, consequentemente, o seu teor de umidade de equilíbrio. As substâncias geradas durante o processo de termorretificação, extraídas em água quente, tem efeito preservativo quando aplicadas à madeira natural, com diferentes resultados entre as espécies florestais. A termorretificação reduziu a capacidade de ação do Cryptotermes brevis, com efeito mais acentuado no Pinus taeda. A remoção dos extrativos da madeira termorretificada, por si só, não implicou no aumento da intensidade da ação dos cupins, o que somente se tornou mais evidente quando aumentou o teor de umidade do material. Em relação ao Nasutitermes corniger, ocorreram diferenças na ação dos cupins em relação ao tipo de oferta de alimento, bem como em relação às espécies de madeira. Para a alimentação forçada, houve acentuado efeito da termorretificação, em ambas as espécies de madeira, tendo ocorrido uma acentuada redução na perda de massa das madeiras quando comparada à madeira original. Constatou-se haver efeito dos extrativos na redução da ação dos cupins de solo, com maior ênfase para a madeira de Pinus taeda. No ensaio de preferência alimentar, nenhum dos tratamentos avaliados foi eficiente para prevenir a degradação pelos cupins, com o Pinus taeda apresentando maior suscetibilidade em comparação com o Corymbia citriodora. Considerando o conjunto dos resultados, conclui-se que a madeira termorretificada é resistente ao ataque de cupins de madeira e essa resistência é decorrente da interação entre a menor higroscopicidade provocada pela modificação química do material e a presença dos extrativos gerados durante o processo de termorretificação; e que o efeito preservativo da termorretificação não é suficiente para indicar o uso da madeira termotratada em contato direto com o solo, devido à suscetibilidade aos cupins subterrâneos. / The thermorectification, a controlled pyrolysis at temperatures ranging between 140°C to 220°C, is considered a technique that could preserve the wood against biological degradation. In this study it was tested the hypothesis that the thermorectification at 200ºC increase the lumber resistance against termite attack, looking to identify if this effect is a result of the reduced available moisture or due the deposition of toxic substances formed during the thermal treatment. It was evidenced that the chemical modifications caused by thermorectification reduced wood sorption capacity and, by consequence, its equilibrium moisture content. The substances formed during the thermal treatment, extracted with hot water, have a preservative effect when applied to natural lumber, with different results between the two wood species. The thermorectification reduced the attack of Cryptotermes brevis and this influence was more effective on Pinus taeda. The removal of extractives from thermotreated wood did not cause an increase in the intensity of termite action, which only became more evident when the lumber moisture content increased. In relation to Nasutitermes corniger, there were differences in the action of termites, depending of the feeding conditions and wood species. In the food choice test, there was an important effect of thermorectifiction in both wood species, reducing the loss of mass due to termite attack when compared to original wood. The extractives also reduced the action of soil termites, with greater emphasis on Pinus taeda lumber. In the no food choice test, no one of the treatments evaluated was enough to prevent the termite action, and it was showed that Pinus taeda wood was more susceptible compared to Corymbia citriodora. Considering all the results, it is possible to conclude that thermorectified lumber is resistant against dry wood termite attack and this resistance is due to interaction between the reduced wood hygroscopicity promoted by the wood chemical changes and the presence of substances generated during the thermal treatment; and the preserving effect of thermorectification is not enough to suggest the use of thermorectified lumber in direct ground contact due its susceptibility to subterranean termite action.
23

Etude de la flore lactique du Nem chua, produit carné fermenté cru traditionnel du Sud Vietnam et maîtrise du processus de fermentation par ajout de souches lactiques sélectionnées spécifiques du produit

Ho, Thi Nguyet Thu 18 December 2008 (has links)
Le Nem chua est un produit vietnamien fermenté à base de viande porcine. Notre étude a pour but de formuler des starters lactiques afin de standardiser le processus de fabrication du Nem chua et améliorer la qualité des produits finis. Le pH de la pâte de viande diminue progressivement tandis que la population lactique se développe au cours des 5 jours de fermentation. Parmi les 131 souches identifiées, les Lactobacillus brevis et Lb. plantarum étaient les plus fréquents. Les autres bactéries lactiques telles que Leuconostoc mesenteroides, Pediococcus pentosaceus, Lactococcus lactis sont présentes mais en plus faible pourcentage. L’utilisation de la combinaison des Lb. brevis et Pe. pentosaceus (6.106 UFC.g-1 pâte de viande, proportion de 1:1) donne des produits préférés par le jury de dégustateurs vietnamiens. Ces résultats permettent d’ouvrir de nouvelles perspectives de production et d’application au niveau industriel des starters lactiques choisis afin d’avoir les produits à la qualité bien maîtrisée et en sécurité alimentaire dans la fabrication des Nem chua du Vietnam, qui pouvant s’appliquer à d’autres fermentations carnées similaires. / Nem chua is a very popular fermented meat product in Vietnam. Our research aimed at the formulation of autochthonous starter cultures in order to standardise the production process of Nem chua and to improve the quality of final product. The paste meat pH progressively decreased while LAB increased during the fermentation. Among 131 isolates identified, the most frequent LAB revealed were Lactobacillus brevis and Lb. plantarum. The other LABs such as Leuconostoc mesenteroides, Pediococcus pentosaceus, Lactococcus lactis, … existed in lowest percentage. The results of our sensorial experiments demonstrated significant effects of Lb. brevis and Pe. pentosaceus strains, which were previously isolated from Nem chua, on the sensory quality of this traditional fermented meat product. The use of both Lb. brevis and Pe. pentosaceus strains (6.106CFU.g-1 meat paste, strain ratio of 1:1) as starters for Nem chua offered the best sensorial quality. These results suggest further studies on the practical ability of using and producing these LABs in combination as commercial starters in order to produce products of well-controlled quality and safety for Nem chua in Vietnam and probably of other similar fermented meat products.
24

Impacts of Karenia brevis on bivalve reproduction and early life history / Impacts de Karenia brevis sur la reproduction et les stades de vie précoces des bivalves

Rolton, Anne 20 January 2015 (has links)
Karenia brevis, le dinoflagellé produisant des brevetoxines (PbTx), est la principale espèce d’efflorescences d’algues toxiques dans le Golfe du Mexique. Les effets de cette algue sur Mercenaria mercenaria et Crassostrea virginica sont méconnus tandis que les efflorescences coïncident avec la période de reproduction de ces espèces. Ce projet avait pour but de déterminer les effets i) d’une exposition à K. brevis en laboratoire et naturelle de terrain sur les processus physiologiques associés à la reproduction de M. mercenaria et C. virginica, et ii) d’une exposition à K.brevis sur la qualité et le développement des gamètes, embryons et larve de ces espèces. Suite à l'exposition des adultes de clams et d’huîtres à K. brevis, les paramètres physiologiques de la reproduction ont été affectés. La présence de PbTx dans les tissus des gamètes et le potentiel transfert maternel de PbTx à la progénie via les ovocytes, pourraient avoir entraîné les effets négatifs observés lors du développement larvaire.Les effets négatifs similaires causés par l'exposition des stades précoces à différentes préparations de cellules de K. brevis suggèrent que d'autres composés toxiques, en plus de PbTx, pourraient être impliqués dans la toxicité et, que la majorité des effets délétères se produisent durant les divisions embryonnaires.Le clam et l’huître américaine sont sensibles à K. brevis. Les effets négatifs sur les adultes et jeunes stades de vie, combinés à une exposition quasi-annuelle aux efflorescences de K. brevis, pourraient engendrer des perturbations majeures sur le recrutement des populations de ces espèces importantes, et avoir des répercussions environnementales et économiques. / The brevetoxin (PbTx) producing dinoflagellate, Karenia brevis is the most prevalent harmful algal bloom species in the Gulf of Mexico. The effects of this alga on Mercenaria mercenaria and Crassostrea virginica are poorly understood yet, blooms typically overlap with periods of reproduction and spawning in these species.The aims of this project were to determine the effects of i) laboratory and field exposure of K. brevis on the reproductive and related physiological processes of adult M. mercenaria and C. virginica and the quality of the offspring that were produced and ii) K. brevis exposure on gamete, embryo and larval development in these species.Following exposure of adult clams and oysters to K. brevis, negative effects were recorded on reproductive and physiological parameters. PbTx was recorded in gamete tissues, and maternal transfer of this PbTx to the offspring via the oocytes, may have resulted in the significant negative effects recorded on larval development up to the end of the lecithotrophic phase.The similar dose-dependent negative effects caused by direct exposure of gamete and early life stages to different cell preparations of K. brevis suggests that other toxic compounds in addition to PbTx may be involved in toxicity and, that the majority of negative effects occur during embryonic divisions.Hard clams and eastern oysters are susceptible to K. brevis exposure. The negative effects on adult and early life stages combined with the near- annual exposure to blooms of K. brevis could cause significant bottle-necks on the recruitment and population dynamics of these important species and, have wider reaching environmental and economic impacts.
25

Physical Mechanisms Driving Harmful Algal Blooms Along the Texas Coast

Ogle, Marcus 1982- 14 March 2013 (has links)
Commonly referred to as “red tide”, harmful algal blooms (HABs) formed by Karenia brevis occur frequently in the Gulf of Mexico (GOM). A bloom is defined as cell abundances >105 cells L-1. This thesis will focus primarily on Karenia brevis, formerly known as Gymnodinium breve, in the Gulf of Mexico. K. brevis is harmful because it produces brevetoxin, a ladder-frame polyether that acts as a potent neurotoxin in vertebrates. K. brevis commonly causes fish kills, respiratory irritation in humans, and Neurotoxic Shellfish Poisoning (NSP) if ingested. Blooms of K. brevis occur almost annually along the West Florida Shelf (WFS) in the late summer and early fall, when the coastal current is favorable for bloom initiation. Along the Texas-Louisiana shelf (TLS) however, blooms of K. brevis are infrequent and sporadic. While much is known of the blooms along the WFS due to their frequent presence, little is known of the mechanisms driving the blooms along the TLS due to their inconsistent presence. To understand the stochastic nature of HABs along the TLS, historical data of bloom occurrences from 1996 to present were compared with NOAA station PTAT2 wind, sea-level pressure, air and water temperature data and NCEP NARR-A sea-level pressure data. The difference in the monthly-mean along-shore component of the wind was statistically significant between bloom and non-bloom years in September (p<<0.001) and April (p=0.0015), with bloom years having a strong downcoast current. Monthly mean water temperature values yielded similar results between bloom and non-bloom years. Both March and September monthly-mean water temperature values were lower during non-bloom years with p-values of 0.01 and 0.048, respectively. These results suggest the possibly of forecasting for HABs along the TLS with currently measured, publicly available data.
26

Vývoj náhrady prvního metatarzofalangeálního kloubu / Development of the first metatarsophalangeal joint replacement

Barták, Vladislav January 2011 (has links)
The work provides a comprehensive overview of the issues hallux rigidus with a focus on the first metatarsophalangeal joint replacement and development of our own implant. The development was built to perform anatomical studies, the results were the basis for the construction of hemiarthroplasty and total arthroplasty. It was necessary to measure the marrow cavities of the distal part of first metatarsal and proximal half of proximal phalanx. We measured the size of the metatarsal head in two planes, and its tendency to diaphysis on the dry preparations. Through these studies we obtained valid data for the construction all components of both hemiarthroplasty and total arthroplasty of specifying the size spectrum. We have verified and then corrected the shape of implant treatment during post-mortem tests on the models. The result is a new type of arthroplasty with their own design to guarantee restoration of joint function and coated with a high osteointegral potential. In clinical studies, we performed 22 implantations of hemiarthroplasty and one implantation of total arthroplasty. Clinical results suggest the fact that the implant will be successful. However the ultimate answer to this question will provide long-term study. The other results presented with a detailed anatomical description show to...
27

Vývoj náhrady prvního metatarzofalangeálního kloubu / Development of the first metatarsophalangeal joint replacement

Barták, Vladislav January 2011 (has links)
The work provides a comprehensive overview of the issues hallux rigidus with a focus on the first metatarsophalangeal joint replacement and development of our own implant. The development was built to perform anatomical studies, the results were the basis for the construction of hemiarthroplasty and total arthroplasty. It was necessary to measure the marrow cavities of the distal part of first metatarsal and proximal half of proximal phalanx. We measured the size of the metatarsal head in two planes, and its tendency to diaphysis on the dry preparations. Through these studies we obtained valid data for the construction all components of both hemiarthroplasty and total arthroplasty of specifying the size spectrum. We have verified and then corrected the shape of implant treatment during post-mortem tests on the models. The result is a new type of arthroplasty with their own design to guarantee restoration of joint function and coated with a high osteointegral potential. In clinical studies, we performed 22 implantations of hemiarthroplasty and one implantation of total arthroplasty. Clinical results suggest the fact that the implant will be successful. However the ultimate answer to this question will provide long-term study. The other results presented with a detailed anatomical description show to...
28

Vectors of Brevetoxins to Marine Mammals

Flewelling, Leanne J 24 October 2008 (has links)
Mass mortalities of Florida manatees (Trichechus manatus latirostris) and bottlenose dolphins (Tursiops truncatus) have been attributed to brevetoxins produced by the Florida red tide dinoflagellate Karenia brevis. The multiple routes through which marine mammals can be exposed to brevetoxins have complicated efforts to understand the mechanisms that lead to mass mortality events. In spring of 2002, 34 endangered Florida manatees died in southwest Florida, and in spring of 2004, 107 bottlenose dolphins died in the Florida Panhandle. These events provided unique opportunities to make clear connections between ingested brevetoxins and marine mammal mortalities without the confounding issues of concurrent exposure through direct contact or inhalation. Prior to 2002, the accumulation of brevetoxins on or in seagrass had never been previously reported, and the delayed or chronic exposure of manatees to brevetoxins through seagrass was not recognized as a threat. Brevetoxins were shown to persist in association with seagrass at high levels for weeks and at lower levels for months in the absence of K. brevis. Analyses of the epiphytes and detritus on the surface of the seagrass leaves as well as of the cleaned seagrass leaves and rhizomes revealed that during a K. brevis bloom as much as half of the toxin present in the seagrass may be associated with the leaves themselves, while after a bloom, the majority of the toxin present is associated with the epiphytes. The 2004 mass mortality of bottlenose dolphins in the Florida Panhandle clearly indicated that fish have the potential to vector brevetoxins to higher tropic levels. Analyses of fish collected live from St. Joseph Bay and southwest Florida revealed that brevetoxin accumulation in fish is a common occurrence. Planktivorous clupeid fish are capable of accumulating high concentrations of brevetoxins within their viscera, and their movement can result in spatial separation of a bloom and animal exposure. Sciaenid species and pinfish also accumulated brevetoxins but to a lower extent. These fish, as well as other omnivorous and piscivorous species, may retain brevetoxins in their tissues at significant concentrations after a bloom has dissipated, which may lead to temporal separation of blooms and animal exposure.
29

Nutrient Distribution Effects from Freshwater Discharge at Franklin Lock and Dam (S-79) in 2005 and 2006 on the Caloosahatchee Estuary and San Carlos Bay, Fort Myers, Florida

Uhlenbrock, Kristan M 01 April 2009 (has links)
Nutrient distribution correlates with discharge of freshwater from Franklin Lock and Dam structure (S-79) by delivery into the Caloosahatchee Estuary (CE) and out of this area, including the surrounding San Carlos Bay (SCB) and adjacent West Florida Shelf. This study analyzed the temporal and spatial distribution of nutrients along the CE waterway and illustrates the effects high freshwater discharge from S-79 has on the coastal and offshore environments, providing a potential source of nutrient input. This study consisted of a 7-station transect monitored biweekly from April 2005 thru August 2006 for nutrients, dissolved oxygen, chlorophyll a, and salinity, along with the corresponding freshwater discharge from S-79. High flow rates correlated (r²=0.7488) with decreased salinity downstream from S-79. At high discharge, over 140 m³ s-¹, nutrients were noticeably transported downstream to SCB; during extreme high flow rates of 285 m³ s-¹, it takes a little less than 4 days for a particle of water to travel from S-79 to the mouth of the estuary. There is evidence from the SATlantic ISUS deployment that pulses of water from S-79 correlated with downstream increased concentrations of nitrate on a daily temporal scale. The assumption that upstream estuarine waters are potentially carrying nutrients downstream can only be conjectured for high flow rates. Low flow rates (less than approximately 28 m³ s-¹) corresponded to hypoxia during the summer months of 2006. The highest chlorophyll a concentrations were found either during decreased flow rates or summer months. Chl a (>3.0 µm) in SCB and the mouth of the CE was above 4 µg l-¹ in July through October 2005 and ranged from 1.24 to 9.62 µg l-¹ in June through August 2006. Karenia brevis blooms were also present during this time. Nutrient loading rates into SCB provided enough DIN and DON to support the maintenance of K. brevis. Therefore monitoring and studying the amount of nutrient loading into coastal and offshore water can elucidate their importance on the surrounding ecology.
30

Brevetoxin Body Burdens in Seabirds of Southwest Florida

Atwood, Karen E 28 March 2008 (has links)
Harmful algal blooms (HABs, or "red tides") of the brevetoxin-producing dinoflagellate Karenia brevis occur periodically along Florida's Gulf coast. Mass mortalities of marine birds have long been associated with these blooms, yet there are few data documenting the accumulation of brevetoxins (PbTx) in the tissues of birds. Post-mortem evaluations were performed on 185 birds representing 22 species collected from October 2001 through May 2006 during red tide and non-red tide events to quantify their body burdens of brevetoxins. A variety of tissues and organs were selected for brevetoxin analysis including blood, brain, heart, fat, stomach or gut contents, intestinal contents or digestive tract, muscle, lung, liver or viscera, kidney, gonads, gallbladder and spleen. Brevetoxin levels in avian tissues ranged from K. brevis which may amass in various tissues of the body. As a consequence, the birds may exhibit acute brevetoxicosis during red tide events or show chronic accumulation effects during non-red tide events.

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