20 resultados para photo-degradation

em Brock University, Canada


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Michael Snow's 'Photo Essay' that adorns a wall in A Block.

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Studies on persistence and degradation of the synthetic pyrethroid insecticides, permethrin and fenvalerate, were carried out under natural environmental conditions of the Niagara Peninsula. Permethrin and fenvalerate were treated on apple foliage atrat~s of 0.21 kg(AI)!ha and 0.14 kg(AI)/ha, respectively. The initial cis- and trans-permethrin spray deposits were found to be 13.5 ppm and 19.2 ppm, respectively and 38.0 ppm was observed for the fenvalerate treated sample. Twenty-three days and 84 days after spray application, permethrin residues were 4.0 ppm and 2.7 ppm for the cis-isomer, whereas they were 7.9 ppm and 4.7 ppm for the trans-isomer, respectively. Residues of fenvalerate 23 days and 84 days after spray application were 13.4 ppm and 8.0 ppm, respectively. The values of observed half-life of cis-permethrin, trans-permethrin and fenvalerate were found to be 42 days, 46 days and 51 days, respectively. Studies were extended to quantitatively determine some of the major degradation compounds of permethrin and fenvalerate, which were expected to be produced as results of ester cleavage of the parent compounds. A permethrin treated sample, 84 days after initial spray application, showed 0.25 and 0.8 ppm of cis- and trans-3-(2,2-dichlorovinyl)-2,2-dimethylcyclopropanecarboxylic acid (C12CA (18), respectively. These two acids were not found as free acids, but found as conjugated compounds. The other expected degradation compounds, 3-phenoxybenzyl alcohol (PBalc (~)),3-phenoxybenz.aldehyde (PBald (38)) and 2- (4-chlorophenyl) isovaleric acid (CPIA (31)) were not detected by the methods employed in this study. The results indicate that these degradation compounds were not present, or, if they were present, their concentrations were too low to detect by the methods used.

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A simple method was developed for treating corn seeds with oxamyl. It involved soaking the seeds to ensure oxamyl uptake, centrifugation to draw off excess solution, and drying under a stream of air to prevent the formation of fungus. The seeds were found to have an even distribution of oxamyl. Seeds remained fungus-free even 12 months after treatment. The highest nonphytotoxic treatment level was obtained by using a 4.00 mg/mL oxamyl solution. Extraction methods for the determination of oxamyl (methyl-N'N'-dimethyl-N-[(methylcarbamoyl)oxy]-l-thiooxamimidate), its oxime (methyl-N',N'-dimethyl-N-hydroxy-1-thiooxamimidate), and DMCF (N,N-dimethyl-1-cyanoformanade) in seed" root, and soil were developed. Seeds were processed by homogenizing, then shaking in methanol. Significantly more oxamyl was extracted from hydrated seeds as opposed to dry seeds. Soils were extracted by tumbling in methanol; recoveries range~ from 86 - 87% for oxamyl. Root was extracted to 93% efficiency for oxamyl by homogenizing the tissue in methanol. NucharAttaclay column cleanup afforded suitable extracts for analysis by RP-HPLC on a C18 column and UV detection at 254 nm. In the degradation study, oxamyl was found to dissipate from the seed down into the soil. It was also detected in the root. Oxime was detected in both the seed and soil, but not in the root. DMCF was detected in small amounts only in the seed.

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On cover: Niagara Falls.

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Photosynthetic state transitions were investigated in the cyanobacterium Synechococcus sp. PCC 6301 by studying fluorescence emission, heat loss, and PS I activity in intact cells brought to state 1 and state 2. 77K fluorescence emission spectra were modelled with a sum of 6 components corresponding to PBS, PS II, and PS I emissions. The modelled data showed a large decrease in PS II fluorescence accompanied with a small increase in the PS I fluorescence upon transition to state 2 for excitation wavelengths absorbed by both PBS and ChI ll.. The fluorescence changes seen with ChI .a. excitations do not support the predictions of the mobile PBS model of state transition in PBS-containing organisms. Measurements of heat loss from intact cells in the two states were similar for both ChI it. and PBS excitations over three orders of magnitude of laser flash intensity. This suggests that the PBS does not become decoupled from PS II in state 2 as proposed by the PBS detachment model of state transition in PBS-containing organisms. PS I activity measurements done on intact cells showed no difference in the two states, in contrast with the predictions of all of the existing models of state transitions. Based on these results a model for state transition In PBScontaining organisms is proposed, with a PS II photoprotectory function.

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This photograph was taken on the wedding day of Richard Nelson Bell and Iris Sloman in 1939. Pictured in the photograph, from left, are: Charles Bell, father of Richard Nelson Bell; Josephine Sloman, mother of Iris; Richard Nelson Bell; Iris Sloman Bell; Mary Bell, mother of Richard Nelson Bell; and Albert Sloman, father of Iris. This family photo was in the possession of Rick Bell, of St. Catharines, Ontario. The Sloman - Bell ancestry includes escaped Black slaves from the United States.

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A black and white photograph taken in 1939 on the occasion of the marriage of Richard Nelson Bell to Iris Sloman. Pictured in the photograph, from left to right, are: Bert Sloman; Richard Nelson Bell; Iris Sloman Bell; and Helen Beatty Sloman. This photograph was in the possession of Rick Bell, the son of Richard Nelson and Iris Bell. The Bell - Sloman family descends from former Black slaves from the United States.Bert Sloman (Albert Edward Sloman) passed away in 1986 at Kitchener-Waterloo, Ontario. His wife Vera Matilda Sloman passed away January 4, 2011 at Cambridge Memorial Hospital. They had a son, Ron Sloman.

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This black and white photograph is believed to be of Albert Sloman (back left), Josephine Sloman (centre) and an unidentified man (right). Iris Sloman, daughter of Albert and Josephine, is thought to be in the front row, centre. The location and date of the photo is unknown, however, it could be in the early 1920s. This photograph was in the possession of Rick Bell, of St. Catharines, son of Iris and Richard Bell. Relatives of the Sloman - Bell family are former Black slaves from the United States.

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This unidentified African Canadian man is photographed at the Dominion Photo Studio, located at 388 Queen St. West in Toronto. The photographer's name is not known. No date is provided, however, the Dominion Studio is listed as operating from 1893-1894. The reverse of the card displays the Dominion Photo Studio stamp in gold lettering (image also attached). The gentleman in this cabinet card is possibly a relative of the Sloman - Bell family, who settled in the London and St. Catharines areas of Ontario. This cabinet card was among the family memorabilia in the possession of Iris Sloman Bell, of St. Catharines. Relatives of the Sloman - Bell family include former African American slaves who came to Canada.The Dominion Portait Co. is listed as operating from 1893-1894 in Toronto. There is an additional listing for the Dominion Portrait Co. (Gourlay and Clark props.) for 1894. Source: Phillips, Glen C. The Ontario photographers list (1851-1900). Sarnia: Iron Gate Publishing Co., 1990. "Cabinet card photographs were first introduced in 1866. They were initially employed for landscapes rather than portraitures. Cabinet cards replaced Carte de visite photographs as the popular mode of photography. Cabinet cards became the standard for photographic portraits in 1870. Cabinet cards experienced their peak in popularity in the 1880's. Cabinet cards were still being produced in the United States until the early 1900's and continued to be produced in Europe even longer. The best way to describe a cabinet card is that it is a thin photograph that is mounted on a card that measures 4 1/4″ by 6 1/2″. Cabinet cards frequently have artistic logos and information on the bottom or the reverse of the card which advertised the photographer or the photography studio's services." Source: http://cabinetcardgallery.wordpress.com/category/cabinet-card-history/

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One hardcover photo album containing black and white photos. Many of the photos were taken in the St. Catharines area. Included are photos of Port Dalhousie, Port Weller, Niagara Falls, Niagara-on-the-Lake and St. Catharines. There are also photos of Braeside, Ont. and the Ottawa valley. Various local landmarks are included, such as the armoury in St. Catharines, Montebello Park, and Martindale pond. Some of the events captured include a train wreck that occurred in St. Catharines in 1914, the visit of the Governor General to St. Catharines in 1914 (featuring the Carnegie library and Post Office and federal building decorated with flags), and an airplane that crashed into a body of water, possibly a plane from an air training camp in Beamsville during World War I. There are also two photos of champion Niagara district basketball teams, possibly taken in the gymnasium building located behind the former St. Catharines Collegiate building (later Robertson School) on Church Street. One photo includes Norman Byrne, Gladys Ansell, Miriam Marshall, Irene Stoter (?), Mildrerd Houston, A. Gardner, and Madeline Jenner. The other photo includes George Moase, W. Bennett, Norman Byrne, Jack Bain, Mr. Brackenbury, Cyril Merriman, Jim Galway, Harry Erskine, and Roy Carpenter.

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Large group of men standing in the tunnel wearing boots and hard hats.

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A photograph for Business Niagara Magazine, featuring (from left to right) : John Howard, Vineland Estates Winery; William Lenko, Daniel Lenko Estate Winery; Gene Luczkiw, The Institute for Enterprise Education; Donald Ziraldo, Inniskillin Wines; Paul Speck, Henry of Pelham Family Estate; Joseph Pohorly, Joseph's Estate Wines. The photograph is dated Monday, January 19, 2004 and has a handwritten message that reads: "Donald. Thanks for making the industry what it is today! Cheers Gene"

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A group standing by a lake or pond. There are three men, one with a cane, and one woman and two small children that appear to be around 1-2 years old.

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A photograph of eight individuals, including Percy Band. There are four men and four women standing and kneeling together.

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A group photo of five individuals, including Percy Band. There are three women and two men. Both men are hiking up their pant legs for the picture.