9 resultados para Reverse Auction
em Brock University, Canada
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A weekly paper published from 1822 to 1856.
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Scientists have been debating for decades the origin of life on earth. A number of hypotheses were proposed as to what emerged first RNA or DNA; with most scientists are in favour of the "RNA World" hypothesis. Assuming RNA emerged first, it fellow that the RNA polymerases would've appeared before DNA polymerases. Using recombinant DNA technology and bioinformatics we undertook this study to explore the relationship between RNA polymerases, reverse transcriptase and DNA polymerases. The working hypothesis is that DNA polymerases evolved from reverse transcriptase and the latter evolved from RNA polymerases. If this hypothesis is correct then one would expect to find various ancient DNA polymerases with varying level of reverse transcriptase activity. In the first phase of this research project multiple sequence alignments were made on the protein sequence of 32 prokaryotic DNA-directed DNA polymerases originating from 11 prokaryotic families against 3 viral reverse transcriptase. The data from such alignments was not very conclusive. DNA polymerases with higher level of reverse transcriptase activity were non-confined to ancient organisms, as one would've expected. The second phase of this project was focused on conditions that may alter the DNA polymerase activity. Various reaction conditions, such as temperature, using various ions (Ni2+, Mn2+, Mg2+) were tested. Interestingly, it was found that the DNA polymerase from the Thermos aquatics family can be made to copy RNA into DNA (i.e. reverse transcriptase activity). Thus it was shown that under appropriate conditions (ions and reactions temperatures) reverse transcriptase activity can be induced in DNA polymerase. In the third phase of this study recombinant DNA technology was used to generate a chimeric DNA polymerase; in attempts to identify the region(s) of the polymerase responsible for RNA-directed DNA polymerase activity. The two DNA polymerases employed were the Thermus aquatic us and Thermus thermophiles. As in the second phase various reaction conditions were investigated. Data indicated that the newly engineered chimeric DNA polymerase can be induced to copy RNA into DNA. Thus the intrinsic reverse transcriptase activity found in ancient DNA polymerases was localized into a domain and can be induced via appropriate reaction conditions.
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Benjamin Rathburn (1790-1873) was a builder, banker and hotel-keeper who was well-known for his work in the development and expansion of Buffalo in the 1830s. He also conducted business in the Village of Niagara Falls. He purchased large tracts of land (largely on credit) with the intent to sell the land at a profit. However, the sales did not meet his expectations and Rathburn found himself over-extended on credit, ultimately leading to his financial ruin.Jesse P. Haines (1793-1877) was an American cartographer who is credited with mapping the Villages of Lockport and Niagara Falls, New York.
Towards reverse engineering of Photosystem II: Synergistic Computational and Experimental Approaches
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ABSTRACT Photosystem II (PSII) of oxygenic photosynthesis has the unique ability to photochemically oxidize water, extracting electrons from water to result in the evolution of oxygen gas while depositing these electrons to the rest of the photosynthetic machinery which in turn reduces CO2 to carbohydrate molecules acting as fuel for the cell. Unfortunately, native PSII is unstable and not suitable to be used in industrial applications. Consequently, there is a need to reverse-engineer the water oxidation photochemical reactions of PSII using solution-stable proteins. But what does it take to reverse-engineer PSII’s reactions? PSII has the pigment with the highest oxidation potential in nature known as P680. The high oxidation of P680 is in fact the driving force for water oxidation. P680 is made up of a chlorophyll a dimer embedded inside the relatively hydrophobic transmembrane environment of PSII. In this thesis, the electrostatic factors contributing to the high oxidation potential of P680 are described. PSII oxidizes water in a specialized metal cluster known as the Oxygen Evolving Complex (OEC). The pathways that water can take to enter the relatively hydrophobic region of PSII are described as well. A previous attempt to reverse engineer PSII’s reactions using the protein scaffold of E. coli’s Bacterioferritin (BFR) existed. The oxidation potential of the pigment used for the BFR ‘reaction centre’ was measured and the protein effects calculated in a similar fashion to how P680 potentials were calculated in PSII. The BFR-RC’s pigment oxidation potential was found to be 0.57 V, too low to oxidize water or tyrosine like PSII. We suggest that the observed tyrosine oxidation in BRF-RC could be driven by the ZnCe6 di-cation. In order to increase the efficiency of iii tyrosine oxidation, and ultimately oxidize water, the first potential of ZnCe6 would have to attain a value in excess of 0.8 V. The results were used to develop a second generation of BFR-RC using a high oxidation pigment. The hypervalent phosphorous porphyrin forms a radical pair that can be observed using Transient Electron Paramagnetic Resonance (TR-EPR). Finally, the results from this thesis are discussed in light of the development of solar fuel producing systems.
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Benjamin Rathburn (1790-1873) was a builder, banker and hotel-keeper who was well-known for his work in the development and expansion of Buffalo in the 1830s. He also conducted business in the Village of Niagara Falls. He purchased large tracts of land (largely on credit) with the intent to sell the land at a profit. However, the sales did not meet his expectations and Rathburn found himself over-extended on credit, ultimately leading to his financial ruin. Jesse P. Haines (1793-1877) was an American cartographer who is credited with mapping the Villages of Lockport and Niagara Falls, New York.
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Notice from the Crown Lands Department of Ottawa that the lands on Long Point, Lake Erie would be offered at public auction on May 4, 1866. This is attached to a small newspaper clipping with the same information, dated April 20, 1866.
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Clipping advertising the auction to be held at 28 College Street in Toronto, Ontario, April 1939.
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Catalogue of items from Devaux [DeVeaux] Hall to be sold in Toronto at auction on April 24-26, 1939. The list of items included items such as lamps, curtain rods, furniture, original art, vases, kitchen items and books. The auction was held in 6 sessions over a 3 day period. There were 855 items listed in the 45 page catalogue. The auction was put on by Ward-Price Auctioneers of Toronto, Apr. 1939.
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Auction Sale notice concerning a brick and stone carpenter shop; a frame wheel-house building and a stone machine shop building all located on Cascade Street in Niagara Falls, Ontario. The Superintendent of the State Reservation at Niagara is listed as Thomas W. Welch. The names Thomas Dolphin – Suspension Bridge; W.A. Frazer – Suspension Bridge; Alice L. [illegible] – Niagara Falls and James C. [illegible] are written on the notice in blue pencil. There is a tear at the top of the notice and wear along the sides. Text is not affected. The item is slightly discoloured and mounted on cardboard, 28 cm x 20 cm, January 27, 1886.