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The comparative ecology of Krefft's River Turtle Eydura krefftii in Tropical North QueenslandTrembath, Dane F., n/a January 2005 (has links)
An ecological study was undertaken on four populations of Krefft�s River Turtle
Emydura krefftii inhabiting the Townsville Area of Tropical North Queensland. Two sites
were located in the Ross River, which runs through the urban areas of Townsville, and two
sites were in rural areas at Alligator Creek and Stuart Creek (known as the Townsville
Creeks). Earlier studies of the populations in Ross River had determined that the turtles
existed at an exceptionally high density, that is, they were superabundant, and so the
Townsville Creek sites were chosen as low abundance sites for comparison.
The first aim of this study was to determine if there had been any demographic
consequences caused by the abundance of turtle populations of the Ross River. Secondly, the
project aimed to determine if the impoundments in the Ross River had affected the freshwater
turtle fauna. Specifically this study aimed to determine if there were any difference between
the growth, size at maturity, sexual dimorphism, size distribution, and diet of Emydura krefftii
inhabiting two very different populations.
A mark-recapture program estimated the turtle population sizes at between 490 and
5350 turtles per hectare. Most populations exhibited a predominant female sex-bias over the
sampling period. Growth rates were rapid in juveniles but slowed once sexual maturity was
attained; in males, growth basically stopped at maturity, but in females, growth continued
post-maturity, although at a slower rate. Sexual maturity was at 6-7 years of age for males,
which corresponded to a carapace length of 150-160 mm, and 8-10 years of age for females,
which corresponded to a carapace length of 185-240 mm. The turtles were omnivorous,
although in the Ross River they ate more submerged vegetation (by percent amount and
occurrence) than those of the Townsville Creeks. Turtles in Townsville Creeks ingested more
windfall fruit and terrestrial insects.
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Ossification of the mammalian metatarsal: proliferation and differentiation in the presence/absence of a defined growth plateReno, Philip Louis 15 August 2006 (has links)
No description available.
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Elicitores abióticos no estresse oxidativo e na expressão de gene da rota de betacianina em Alternanthera philoxeroides (Mart.) Griseb. / Abiotic elicitors in oxidative stress and in gene expression of the betacyanin route in Alternanthera philoxeroides (Mart.) GrisebRibeiro, Márcia Vaz 31 October 2011 (has links)
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Previous issue date: 2011-10-31 / The medicinal Alternanthera (Amaranthaceae) species, such as A. philoxeroides, present a great
variety of bioactive compounds, among which are the betacyanins, nitrogen pigments that belong
to the betalains class. These compounds are widely used as additives for food and drugs, due to
their antioxidant action and lack of toxicity, which have already been proven. Techniques have
been developed in order to improve productivity and performance of this pigment, one of those is
the use of in vitro elicitors or in vivo stressing agents. Both have an important role in the
transduction process of signals that regulate the defense genes in plants, acting as stimulators of
production or degradation of several primary and secondary metabolites. This work aimed to
assess, in A. philoxeroides plants, the growth and production characteristics of betacyanin in in
vitro plants; the levels of photosynthetic pigments, betacyanins, lipid peroxidation and antioxidant
enzymes activity in in vivo plants under salt stress, and also to quantify the level of betacyanin and
the 5GT-DBs gene expression in the biosynthetic route of this compound in in vitro plants
submitted to elicitation by NaCl and by tyrosine. For this, three trials were conducted. In the first
one, A. philoxeroides explants were inoculated in MS medium with increasing NaCl concentrations
(0, 50, 100, 150, 200 and 250 mM) for 35 days. In the second one, plants from in vitro cultures
were acclimatized in greenhouses and irrigated with a sodium chloride solution (0, 200 and 400
mM) for 30 days. The third trial had two essays, one composed of in vitro A. philoxeroides plants in
a liquid MS medium in vermiculite substrate for 35 days. After this period, a NaCl solution (400
mM) was added to the medium and the shoots were collected after 0, 12, 24, 36 and 48 hours of
exposure. In the second one, nodal segments were inoculated in MS medium with and without
tyrosine (0 e 75 µM), and its aerial parts were collected after 35 days. In the growth analysis,
reduction of the averages was observed for the following variables: height, number of shoots,
number of sprouts and root number and length; for the plants that have grown in the sodium
chloride medium. The highest concentrations of betacyanins were found in the stalks of plants from
MS medium, with 50 mM of NaCl. After 30 days of in vivo cultivation, the levels of chlorophyll a,
chlorophyll b and carotenoids decreased as the salt concentration increased, while the reason of
chlorophyll a/b in plants submitted to a higher salt concentration presented a difference in
comparison to the control. Higher levels of betacyanin were observed on stalks, when compared to
the leaves, in the highest salt concentrations. On the leaves, there was a significant increase of
lipid peroxidation and superoxide dismutase activity. On the roots, there was an increase of
enzymes catalase and ascorbate peroxidase. Regarding the analysis of differential expression
(qRT-PCR), it was possible to observe that from 12 to 24 hours of salt stress, the 5-GT gene
expression firstly increased, then there was a decrease in 36 hours and a new increase in 48
hours. The 5-GT gene also showed increased expression as a response to tyrosine. It was
possible to conclude that A. philoxeroides elicited in vitro with sodium chloride present a decrease
of the assessed morphological parameters, but in low concentrations betacyanin synthesis is
stimulated. Salt stress causes greater degradation in the photosynthetic pigments, increment of
betacyanin synthesis in stalks and damage to the cell membranes of the leaves. The increase of antioxidant enzymes activity stimulated the protective system against oxidative stress on in vivo A.
philoxeroides plants. It is suggested that in this species, the enzyme bethanidine 5-Oglucosyltransferase
reaches its highest expression in 48 hours of exposure to salt elicitation and
also when grown in a medium containing tyrosine. / As espécies medicinais do gênero Alternanthera (Amaranthaceae) como A. philoxeroides
apresentam uma variedade de compostos bioativos, entre eles as betacianinas, que são
pigmentos nitrogenados pertencentes à classe das betalaínas. Esses compostos são
amplamente utilizados como aditivos de produtos alimentícios e medicamentos devido à
sua comprovada ação antioxidante e ausência de toxicidade. Técnicas têm sido
desenvolvidas para aprimorar a produtividade e o rendimento deste pigmento, sendo uma
delas o uso de elicitores in vitro ou agentes estressantes in vivo. Ambos apresentam um
importante papel no processo de transdução de sinais que regulam os genes de defesa
nas plantas, agindo como estimuladores para a produção e ou degradação de diversos
metabólitos, tanto primários quanto secundários. Assim, o objetivo do presente trabalho
foi avaliar em plantas de A. philoxeroides, as características de crescimento e produção
de betacianina em plantas cultivadas in vitro; os teores dos pigmentos fotossintéticos,
betacianinas, peroxidação lipídica e atividade de enzimas antioxidantes em plantas
cultivadas in vivo, sob estresse salino, além de, quantificar o teor de betacianina e a
expressão do gene 5GT-DBs envolvido na rota biossintética, deste composto, em plantas
in vitro submetidas à elicitação por NaCl e pelo aminoácido tirosina. Para isso, foram
conduzidos três experimentos. No primeiro, explantes de A. philoxeroides foram
inoculados em meio MS, com concentrações crescentes de NaCl (0, 50, 100, 150, 200 e
250 mM), durante 35 dias. No segundo, plantas provenientes da cultura in vitro foram
aclimatizadas em casa de vegetação e irrigadas com solução de cloreto de sódio (0, 200
e 400 mM), por 30 dias. O terceiro experimento contou com dois ensaios, sendo o
primeiro composto de plantas de A. philoxeroides cultivadas in vitro, em meio MS líquido,
no substrato vermiculita, durante 35 dias. Após esse período, foi adicionada ao meio,
solução de NaCl (400 mM) e coletada a parte aérea das plantas após 0, 12, 24, 36 e 48
horas de exposição ao sal, Já o segundo, segmentos nodais foram inoculados em meio
MS, na presença e ausência de tirosina (0 e 75 µM), tendo sua parte aérea coletada após
35 dias de cultivo. Nas análises de crescimento observou-se redução das médias para as
variáveis altura, número de gemas, número de brotos e no número e comprimento de raiz,
nas plantas crescidas nos meios contendo cloreto de sódio. As maiores concentrações de
betacianinas foram encontradas nos caules de plantas cultivadas em meio MS com 50
mM de NaCl. Após 30 dias de cultivo in vivo os teores de clorofilas a, clorofila b, e
carotenóides decresceram à medida que aumentou a concentração de sal, enquanto a
razão clorofila a/b das plantas submetidas à maior concentração de sal apresentou
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Oligo(3-hexylthiophene) Wires for needs of Single-Molecule NanoelectronicsÖktem, Gözde 24 August 2017 (has links) (PDF)
A material to function as a molecular electronic device should have a strong coupling with electrodes through appropriate and well-defined anchoring groups and have to support an effective traveling of charges via a conjugated molecular backbone. Oligo(3-hexylthiophene)s are π-conjugated molecules having large applicability in several areas of organic electronics owing interesting semiconducting properties and they also hold great promises in the field of single-molecule electronics. Polymerization methods, in principle, allow construction of long conjugated systems in a single synthetic step, however, most of them lack precision. This work uses externally initiated chain-growth Kumada Catalyst - Transfer Polycondensation (KCTP) for the synthesis of semiconductive oligo(3-hexylthiophene) wires with controllable molecular weights, low polydispersities, high regioregularities as well as with well-defined starting and end groups. In such a way, the synthetic efforts were compromised to obtain relatively easy a series of very complex molecular wires with a reasonable structural precision. To modulate the electronic function of oligomer backbones, specific charge-transfer moieties (DMA-TCBD and Fc-TCBD) were inserted as side chains or end groups. In-situ termination of KCTP with ZnCl-functionalized electron rich alkynes followed by Diederich-type click reaction resulted in the synthesis of asymmetrical oligo(3-hexylthiophene)s having thiolate-functionalized starting groups and donor-functionalized end-groups with a high degree of end-group functionalizations. Side chains of double-thiolate functionalized oligo(3-hexylthiophene)s, on the other hand, were further modified with the insertion of charge-transfer groups by post-polymerization functionalization. While the facile synthesis and modification of oligo(3-hexylthiophene)s enable the control over the molecular backbone, the specific starting and end anchoring groups allow the control over the electrode oligomer interface. To assure the formation of alligator clips between oligomer backbone and Au electrode, the optimizations including proper end-group conversion into mild counterparts followed by in-situ deprotection into thiolates and the binding abilities on gold were investigated. Finally, the conductance of bis-end functionalized oligo(3-hexylthiophene)s was preliminarily studied through oligomer backbone by Mechanically Controllable Break Junctions (MCBJs) setup and through oligomer-attached DNA origami-templated gold nanowires by individual electrical contacts. The developed KCTP-based synthetic route, at the end, presents new opportunities for the facile synthesis, the ease of modification and the feasibility of asymmetrical and side chain functionalized oligo(3-hexylthiophene) wires for needs of molecular electronics.
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Oligo(3-hexylthiophene) Wires for needs of Single-Molecule NanoelectronicsÖktem, Gözde 09 August 2017 (has links)
A material to function as a molecular electronic device should have a strong coupling with electrodes through appropriate and well-defined anchoring groups and have to support an effective traveling of charges via a conjugated molecular backbone. Oligo(3-hexylthiophene)s are π-conjugated molecules having large applicability in several areas of organic electronics owing interesting semiconducting properties and they also hold great promises in the field of single-molecule electronics. Polymerization methods, in principle, allow construction of long conjugated systems in a single synthetic step, however, most of them lack precision. This work uses externally initiated chain-growth Kumada Catalyst - Transfer Polycondensation (KCTP) for the synthesis of semiconductive oligo(3-hexylthiophene) wires with controllable molecular weights, low polydispersities, high regioregularities as well as with well-defined starting and end groups. In such a way, the synthetic efforts were compromised to obtain relatively easy a series of very complex molecular wires with a reasonable structural precision. To modulate the electronic function of oligomer backbones, specific charge-transfer moieties (DMA-TCBD and Fc-TCBD) were inserted as side chains or end groups. In-situ termination of KCTP with ZnCl-functionalized electron rich alkynes followed by Diederich-type click reaction resulted in the synthesis of asymmetrical oligo(3-hexylthiophene)s having thiolate-functionalized starting groups and donor-functionalized end-groups with a high degree of end-group functionalizations. Side chains of double-thiolate functionalized oligo(3-hexylthiophene)s, on the other hand, were further modified with the insertion of charge-transfer groups by post-polymerization functionalization. While the facile synthesis and modification of oligo(3-hexylthiophene)s enable the control over the molecular backbone, the specific starting and end anchoring groups allow the control over the electrode oligomer interface. To assure the formation of alligator clips between oligomer backbone and Au electrode, the optimizations including proper end-group conversion into mild counterparts followed by in-situ deprotection into thiolates and the binding abilities on gold were investigated. Finally, the conductance of bis-end functionalized oligo(3-hexylthiophene)s was preliminarily studied through oligomer backbone by Mechanically Controllable Break Junctions (MCBJs) setup and through oligomer-attached DNA origami-templated gold nanowires by individual electrical contacts. The developed KCTP-based synthetic route, at the end, presents new opportunities for the facile synthesis, the ease of modification and the feasibility of asymmetrical and side chain functionalized oligo(3-hexylthiophene) wires for needs of molecular electronics.
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Measurement of 222Rn Exhalation Rates and 210Pb Deposition Rates in a Tropical EnvironmentLawrence, Cameron Eoin January 2006 (has links)
This thesis provides the measurements of 222Rn exhalation rates, 210Pb deposition rates and excess 210Pb inventories for locations in and around Ranger Uranium Mine and Jabiru located within Kakadu National Park, Australia. Radon-222 is part of the natural 238U series decay chain and the only gas to be found in the series under normal conditions. Part of the natural redistribution of 222Rn in the environment is a portion exhales from the ground and disperses into the atmosphere. Here it decays via a series of short-lived progeny, that attach themselves to aerosol particles, to the long lived isotope 210Pb (T1/2 = 22.3 y). Attached and unattached 210Pb is removed from the atmosphere through wet and dry deposition and deposited on the surface of the earth, the fraction deposited on soils is gradually transported through the soil and can create a depth profile of 210Pb. Here it decays to the stable isotope 206Pb completing the 238U series. Measurements of 222Rn exhalation rates and 210Pb deposition rates were performed over complete seasonal cycles, August 2002 - July 2003 and May 2003 - May 2004 respectively. The area is categorised as wet and dry tropics and it experiences two distinct seasonal patterns, a dry season (May-October) with little or no precipitation events and a wet season (December-March) with almost daily precipitation and monsoonal troughs. November and April are regarded as transitional months. As the natural processes of 222Rn exhalation and 210Pb deposition are heavily influenced by soil moisture and precipitation respectively, seasonal variations in the exhalation and deposition rates were expected. It was observed that 222Rn exhalation rates decreased throughout the wet season when the increase in soil moisture retarded exhalation. Lead-210 deposition peaked throughout the wet season as precipitation is the major scavenging process of this isotope from the atmosphere. Radon-222 is influenced by other parameters such as 226Ra activity concentration and distribution, soil porosity and grain size. With the removal of the influence of soil moisture during the dry season it was possible to examine the effect of these other variables in a more comprehensive manner. This resulted in categorisation of geomorphic landscapes from which the 222Rn exhalation rate to 226Ra activity concentration ratios were similar during the dry season. These results can be extended to estimate dry season 222Rn exhalation rates from tropical locations from a measurement of 226Ra activity concentration. Through modelling the 210Pb budget on local and regional scales it was observed that there is a net loss of 210Pb from the region, the majority of which occurs during the dry season. This has been attributed to the fact that 210Pb attached to aerosols is transported great distance with the prevailing trade winds created by a Hadley Circulation cell predominant during the dry season (winter) months. By including the influence of factors such as water inundation and natural 210Pb redistribution in the soil wet season budgeting of 210Pb on local and regional scales gave very good results.
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