This study focuses on understanding the photochemical reactions that occur between ultraviolet stabilizers and lignin during irradiation in order to further comprehend the photo-protection mechanisms of these stabilizers during brightness reversion. The stabilizers chosen for study included a variety of ultraviolet absorbers (UVAs), in addition to a hindered nitroxide free radical (4-hydroxy-TEMPO). Irradiated samples were analyzed using quantitative 31P NMR, in addition to a technique known as 'Derivatization Followed by Reductive Cleavage'. / Benzophenone-based UVAs have been shown to be actively involved in photochemical reactions with lignin during irradiation, while benzotriazole-based UVAs are comparatively photostable under identical irradiation techniques. All additive combinations were found to inhibit the formation of carboxylic acids and photochemical condensation reactions in lignin; however, the joint application of 2,4-DHB and 4-hydroxy-TEMPO demonstrated synergistic inhibition of these reactions. / All additive combinations were shown to impede the formation of catechol structures and to retard the cleavage of lignin beta-arylether groups during irradiation. The combined use of Tinuvin 1130 and 4-hydroxy-TEMPO provided the most efficient inhibition of these reactions. These results provide insight into the excellent photoyellowing inhibition provided by this additive combination when applied onto mechanical pulps.

Researchers have linked resin and fatty acids (RFAs) to acute toxicity, especially in thermomechanical and chemithermomechanical pulp and paper mill effluents. Thus, the measurement of total RFAs may be a rapid, inexpensive alternative to standard methods of toxicity monitoring, such as 96-hour rainbow trout testing. Current procedures for the analysis of RFAs typically involve solvent extraction and concentration, derivatization, and analysis by GC, HPLC, or TLC. These procedures are far too expensive, complicated, and time-consuming for implementation at mill sites. / This thesis reports the development of a rapid, colourimetric assay based on the dye methylene blue (MB) for the quantification of resin and fatty acids in pulp and paper mill effluents. This MB assay uses the complexation of the cationic organic dye molecule to the carboxylic acid groups of RFAs to form a measurable chromophore. The electrically neutral, blue-coloured complexes are then extracted into a poorly polar organic solvent, dichloromethane. The measured absorbance at 655 nm is directly related to the total RFA concentration in the effluent sample. / The methylene blue assay is inexpensive and simple to use. It has a method detection limit of 0.589 mg/L total RFA. There are good correlations between the results obtained using the methylene blue assay and a well-established GC assay, and between RFA concentrations measured by the MB assay and acute toxicity measured by Microtox. The assay is sufficiently simple and rapid to be practical for routine in-mill monitoring.

Column flotation as a concept was introduced approximately 90 years ago at Inspiration Copper Co., Arizona, with the first successful installation occurring at Les Mines Gaspe, Quebec, in 1981. Column flotation has since been applied to many other industries including deinking of recycled paper. / The research is a comparison of industrial bubble generating devices in a pilot and laboratory column using water/Dowfroth and pulp sampled on-line from a local deinking plant. The pilot column tested combinations of 6, 4 and 2 stainless steel (ss) porous spargers, and filter cloth and jetting sparger; the lab column used a single ss porous sparger. Long term tests on the pilot column were also done to evaluate maintenance issues. / Trends from the water/Dowfroth tests were used to predict results using pulp. Six ss spargers outperformed the other spargers in all cases. The performance of the lab column sparger matched 4 spargers, with the filter cloth performing marginally better than the jetting sparger or 2 spargers. / Gas holdup (Eg) and bubble surface area flux (Sb) gave good correlation with ink removal with all spargers failing within a narrow range. Surface area flux is suggested over Eg unless bubble diameter or superficial gas velocity are indeterminable. Sb > 100 s-1 gave ink removals equal to the plant Voith cells. An Sb below 40 s-1 gave zero ink removal. The lab and pilot column followed slightly different trends which was attributed to column diameter (i.e., wall effects). / The ss and filter cloth spargers present long term maintenance issues due to plugging. The performance of the 6 ss spargers decreased more quickly than any other during the long term tests, attributed to lower air velocities per pore.

This thesis investigates the changing forms and roles of science, technology, and expert knowledge in agricultural development in Zambia from 1945 to the present day. The main focus is on the changing ideologies, polices, and technologies that different development agencies have used to transform agriculture in sub-Saharan Africa, and the persistent concerns about rural hunger and low agricultural productivity. My central argument is that contests over expert knowledge and technology have played a key role in the formulation and implementation of agricultural development policies in colonial Northern Rhodesia and then independent Zambia. Another argument is intertwined with this, namely that a historical approach is essential to understanding the origins, operation, and outcomes of development policies. The argument is developed in five chronologically sequenced case studies of particularly significant and innovative agricultural development projects, technologies, and research programmes. These studies in part stand alone, each filling a gap in the history of development in Zambia and sub-Saharan Africa more generally. By focusing upon common issues and questions through the studies, however, I explore broader themes in the history of development knowledge and practice, and the history of science and technology. I have framed my approach in two linked areas. The first concerns development experts, those who are responsible for creating new knowledge about peasant society and deploying new technologies and programmes to transform it. The thesis investigates how and why it is that certain people and institutions gain influence and acquire the status of 'development experts', and how the category of 'development expert' is subject to historical change. My main argument in this area is that development experts were more divided than is commonly acknowledged in histories of development which rely upon a more abstract and unitary notion of expertise. The second area of focus concerns how these 'divided experts' attempt to manage the peasantry's integration with capitalist social relations through the manipulation of the 'productive forces': technologies, production techniques, environmental resources, and methods of organising labour. My argument here is that technology has been used as a disruptive force; development programs have revolved around the introduction of new technologies as a means of reworking socio-ecological relations.

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Trees of Slash pine showed reduced growth, by an order of magnitude, following exposure to two hurricanes (Elena and Kate) in 1985. The reduced growth is caused by salt spray chlorosis and/or defoliation from high winds. Ring width, radial tracheid diameter, radial cell number, tracheid length and microfibril angle were measured for samples from before and after major storms. Data for ring width, earlywood radial cell diameter and cell number were not normally distributed, while data for latewood radial cell diameter, tracheid length and microfibril angle showed normal distributions. There were significant statistical differences for all main effects for ring width, earlywood radial cell diameter, cell number and tracheid length. The data for latewood radial cell diameter show significant differences for effects of time and height, but not for compass direction. There are significant differences in earlywood cellulose microfibril angle for height effects, and no difference for time and direction effects. Data for latewood cellulose microfibril angle show significant differences for the effects of time and height. / Source: Dissertation Abstracts International, Volume: 55-01, Section: B, page: 0016. / Major Professor: Loran C. Anderson. / Thesis (Ph.D.)--The Florida State University, 1993.

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