9 resultados para Additions

em Brock University, Canada


Relevância:

10.00% 10.00%

Publicador:

Resumo:

The work to be presented herein illustrates several important facts. First, the synthesis of BIBOL (19), a 1,4-diol derived from the monoterpene camphor has allowed us to demonstrate that oxidative dimerizations of enolates can, and do proceed with nearly complete diastereoselectivity under kinetically controlled conditions. The yield of BIBOL is now 50% on average, with a 10% yield of a second diastereomer, which is likely the result of a non-kinetic hydride reduction, thereby affording the epimeric alcohol, 20, coupled on the exo face of camphor. This implies the production of 60% of a single coupling diastereomer. No other diastereomers from the reduction were observed. The utility of BEBOL has been illustrated in early asymmetric additions of diethylzinc to aryl aldehydes, with e.e.'s as high as 25-30%. '^' To further the oxidative coupling work, the same methodology which gave rise to BIBOL was applied to the chiral pool ketone, menthone. Interestingly, this gave an excellent yield of the a-halohydrin (31), which is the result of a chlorination of menthone. This result clearly indicates the high stereoselectivity of the process regardless of the outcome, and has illustrated an interesting dichotomy between camphor and menthone. The utility of the chlorination product as a precursor other chiral ligands is currently being investigated. > ' Finally, a new series of 1,3-diols as well as a new aminoalcohol have successfully been synthesized from highly diastereoselective aldol/mannich reactions. Early studies have indicated their potential in asymmetric catalysis, while employing pi-stack interactions as a means of controlling enantioselective aldol reactions.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

The maximum amount of ethyl carbamate (EC), a known animal carcinogen produced by the reaction of urea and ethanol, allowed in alcoholic beverages is regulated by legislation in many countries. Wine yeast produce urea by the metabolism of arginine, the predominant assimilable amino acid in must. This action is due to arginase (encoded by CARl). Regulation of CARl, and other genes in this pathway, is often attributed to a well-documented phenomenon known as nitrogen catabolite repression. The effect of the timing of di-ammonium phosphate (DAP) additions on the nitrogen utilization, regulation of CARl, and EC production was investigated. A correlation was found between the timing of DAP addition and the utilization of nitrogen. When DAP was added earlier in the fermentations, less amino nitrogen and more ammonia nitrogen was sequestered from the media by the cells. It was also seen that early DAP addition led to more total nitrogen being used, with a maximal difference of ~25% between fermentations where no DAP was added versus addition at the start of the fermentation. The effect of the timing ofDAP addition on the expression of CARJ during fermentation was analyzed via northern transfer and the relative levels of CARl expression were determined. The trends in expression can be correlated to the nitrogen data and be used to partially explain differences in EC formation between the treatments. EC was quantified at the end of fermentation by GC/MS. In Montrachet yeast, a significant positive correlation was found between the timing of DAP addition, from early to late, and the final EC concentration m the wine (r = 0.9226). In one of the fermentations, EC levels of 30.5 ppb was foimd when DAP was added at the onset of fermentation. A twofold increase (69.5 ppb) was observed when DAP was added after 75% of the sugars were metabolized. When no DAP was added, the ethyl carbamate levels are comparable at a value of 38 ppb. In contrast, the timing of DAP additions do not affect the level EC produced by the yeast ECU 18 in this manner. The study of additional yeast strains shows that the effect of DAP addition to fermentations is strain dependent. Our results reveal the potential importance of the timing of DAP addition to grape must with respect to EC production, and the regulatory effect of DAP additions on the expression of genes in the pathway for arginine metabolism in certain wine yeast strains.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

The peripheral circulating erythrocytic system of the rainbow trout, l3 almo gairdner , was examined in vitro in relation differences in the morphology and multiple hemoglobin system organization of adult and juvenile red cells. Cells were separated by velocity sedimentation under unit gravity, a procedure requiring red cell exposure to an incubation medium for periods of at least three hours. Therefore , this must provide an environment in which red cells remain in a condition approximaing normalcy. Previous studies having demonstrated commonly employed media to be ineffective in this regard , a medium was developed through modification of Cortl and saline. One of the principal additions to this me dium , norepinephrine, altered cell regulation of intracellular calcium, magnesium and chloride concentrations. Catecholamine involvement was also suggeste d in the synthes is of hemoglobin . The procedure was found to separtate cells primarily by density and, to a lesser extent, by shape. Characterization of red cells revealed two subpopulations to exist . The first comprised the bulk of the cell population, and were of greater l ength, width, volume and major:minor axis ratio than the smaller population; these were adult cells. The later, juvenile cells were of smaller overall size and were more spherical in shape . Juvenile cells also possessed fewer electrophore tpically distinguishable isomorphs than did adults with only eight of eleven hemoglobin component s typically found With maturation,hemoglobin complement with the development of three more bands. The total complement of the adult cell contained 7 cathodal bands and four anodal hemoglobin isomorphs. Bands acquired with maturation comprised the smallest percentage of the cells hemoglobin. each averaging less than one-percent of the total. Whether these additional bands are derived through degradation and reaggregation of existing components or are the product of pe gQy2 synthesis is not yet known.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

This thesis explores the comparison utilitarianism and Buddhist ethics as they can be applied to animal research. It begins by examining some of the general discussions surrounding the use of animals in research. The historical views on the moral status of animals, the debate surrounding their use in animals, as well as the current 3R paradigm and its application in Canadian research are explored. The thesis then moves on to expound the moral system of utilitarianism as put forth by Jeremy Bentham and John Stuart Mill, as well as contemporary additions to the system. It also looks at the basics of Buddhist ethics well distinguishing the Mahayana from the Therevada. Three case studies in animal research are used to explore how both systems can be applied to animal research. It then offers a comparison as to how both ethical systems function within the field of animal research and explores the implications in their application on its practice.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

The menu, with wine list from the Ladies’ and Gentlemens’ Ordinary of the Clifton House hotel in Niagara Falls, Ont. Also includes handwritten additions or alterations to the printed menu. The proprietors of the hotel were D.H. Bromley & Co. The Clifton House hotel was built in 1833 and destroyed by fire in 1896. It was known as the finest hotel on the Canadian side of the falls. Oakes Garden Theatre marks its location today.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Stocks added to (deleted from) the Russell 2000 and the S&P 600 indexes experience positive (negative) abnormal returns following the announcement. However, researchers disagree on whether these abnormal returns are permanent or temporary and offer competing explanations. I address this controversy by examining market reactions for firms that are added to or deleted from the FTSE Small Cap index (the main testing sample) and the S&P/TSX SmallCap index (the comparison sample). For the main testing sample, all stocks except pure additions, experience a permanent price change that is accompanied by a permanent change in liquidity. However, for the comparison sample, abnormal returns over the announcement period fully reverted within 30 days. In further examination of stock liquidity for the main testing sample, sample stocks experience permanent change in liquidity. Taken together, the observed results support the price pressure and liquidity hypotheses.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

The origins of the Welland County Fair date back to the founding of the County of Welland in 1852. A provincial charter was issued in 1853 to create the Welland County Agricultural Society that was to operate the Fair. In 1970, the Welland County Fair became the Niagara Regional Exhibition, and the Society became known as the Niagara Regional Agriculture Society. The Society seeks to “encourage interest, promote improvements in and advance the standards of agriculture, domestic industry and rural life”. The Welland Festival of Arts was developed in 1986 in order to revitalize the town’s economy. An “outdoor art gallery” was created by painting murals on buildings that depicted the town’s heritage, a concept successfully adopted by the town of Chemainus, B.C. The first mural was completed in the summer of 1988, and by 1991 there were a total of 28 murals around the city. The endeavour proved successful: in the years that followed the creation of the Festival, two new hotels were constructed, a third was expanded, and there was an addition to the Seaway Mall to accommodate the increased tourist traffic. Optimist International is a non-profit organization that strives to “bring out the best in kids” . The first Canadian club was formed in Toronto in 1924. The Welland branch of the Optimist Club was founded in 1937. The first Welland County General Hospital opened in 1908. As the population increased, it became necessary to expand the existing facilities. Additions were made to the original structure with an East wing in 1930 and a children’s ward in 1931. However, in the 1950’s, the hospital was operating beyond optimum capacity and the need for a larger facility was clear. It was decided that a new hospital would be built, which opened in April 1960. The new hospital had 259 beds and 51 bassinets. Further additions were made in 1967 and 1978. The County of Welland was formed in 1850 when it was officially separated from Lincoln County, however, the two counties continued to operate together until 1856 when a new County building and jail for Welland County were completed. That same year, the first meeting of the Council of the Corporation of Welland County took place. The final meeting of the Council took place on December 18, 1969. The following year, the County of Welland merged with Lincoln County to form the Regional Municipality of Niagara. The Welland Mills in Thorold, Ont., was built in 1846-1847 by Jacob Keefer and is thought to have been one of the largest flour mills in Upper Canada. Ownership of the mill changed several times over the years and previous owners include the Howland family, the Hedley Shaw Milling Company and the Maple Leaf Milling Company. In 1986, the building received a heritage plaque from the Ontario Heritage Foundation, an agency of the Ontario Ministry of Culture and Recreation. At this time, the mill was no longer in operation and was being used for storage by Fraser, Inc. By 2006, the dilapidated building had been redeveloped into18 apartments and 2 floors of commercial space, while maintaining many heritage features. The building is currently known as the Welland Mills Centre.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

We examine stock market reactions around the Nasdaq-100 Index reconstitutions. We find a symmetric and transitory price response accompanied by a significant increase in trading volume on the effective date. Firms added to the Nasdaq-100 Index experience significant increases in institutional ownership, the number of market makers, and the number of shareholders. In contrast, firms removed from the index show significant decreases in the number of institutional shareholders. Additions to the Nasdaq-100 Index also show significant increases in four liquidity measures, whereas deletions demonstrate significant decreases in two liquidity measures. These changes in liquidity are related to the abnormal return on the announcement day. Taken together, the results suggest support for the price pressure, liquidity, and investor awareness hypotheses.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

The origins of the St. Catharines Collegiate Institute can be traced back to the formation of the Grantham Academy on Church St. in 1829. In 1845, the name was changed to the St. Catharines District Grammar School and in 1890 the Grammar School was renamed the St. Catharines Collegiate Institute. The current site of the school on Catherine Street was built in 1923 to accommodate the increasing demand for technical education, and became known as the St. Catharines Collegiate Institute and Vocational School. The school was enlarged with additions in 1945, 1965 and 1969. In 2006, the school underwent major renovations, which were completed in 2008. It is currently a secondary school administered by the District School Board of Niagara.