published_or_final_version / Dentistry / Master / Master of Orthodontics

No description available.

No description available.

No description available.

The broader technical objective of this work is to develop a strategy for using the biopolymer lignin in a wide variety of surfactant applications through polymer grafting. These applications include emulsion stabilizers, dispersants and foaming agents. The scientific objective of the research performed within this thesis is to understand the effect of molecular architecture and polymer grafting on the interfacial activity at the air-liquid, liquid-liquid and solid-liquid interface. Research has focused on designing of these lignopolymers with controlled architecture using polyethylene glycol, poly(acrylic acid) and polyacrylamide grafts. The interfacial activity for all polymer grafts has been tested at all three interfaces using a broad range of techniques specific to the interface. Results have shown that the hydrophobicity of the lignin core is responsible for enhanced interfacial activity at the air-liquid and liquid-liquid interface. Conversely, improved hydrophilicity and “electrosteric” interactions are required for higher interfacial activity of the lignin at the liquid-solid interface. The high interfacial activity of the polymer-grafted lignin observed in the air-liquid and liquid-liquid interfaces not only resulted in viscosity reduction but also strength enhancement at the liquid-solid interface. The broader implication of this study is to be able to predict what chemical functionalities need to be adjusted to get the desired viscosity reduction.

Master of Science / Department of Horticulture, Forestry, and Recreation Resources / Cary L. Rivard / As populations of cities continue to increases, communities in the United States are implementing urban food systems including locally-cultivated produce. Urban and peri-urban farmers apply intensive production systems, including high tunnels, to better utilize limited space. Grafting tomato with vigorous rootstocks provides the potential for higher yields. Our first objective was to identify tomato rootstocks that improve productivity in high tunnel environments with no soilborne diseases in the Central U.S. Eight replicated high tunnel trials were conducted at four sites in northeastern Kansas in 2013 and 2014. We selected 'BHN 589' scion for all sites and evaluated seven rootstocks. Grafting with ‘Maxifort’, ‘Multifort’, ‘Arnold’, ‘DRO 131’, and ‘Colosus’ rootstocks resulted in significant increases in total fruit yield, which ranged from 40% to 73% when compared to nongrafted plants (P<0.05). No significant increases in yield were observed for ‘RT-1028’ and ‘RST-04-106’ rootstocks. Our results suggested that tomato growers that utilize high tunnels should be strategic when selecting rootstocks. Our second objective was to develop simple propagation techniques that yield high quality grafted transplants for small-batch propagators. Formation of adventitious roots (AR) from the scion can result in poor quality plants and loss of rootstock function/benefit. Greenhouse studies were designed to investigate how leaf removal (LR) affects AR formation and plant growth post-grafting. We applied three treatments, 0% LR, 50% LR, and 90% LR, to the ‘BHN 589’ scion and then grafted them onto ‘Maxifort’ rootstock. The experiment included 4 replicated blocks and was conducted in three different healing chambers. Our results indicate that both 50% and 90% LR significantly decreased AR formation in the low humidity chamber, but only 90% LR reduced AR formation in the chambers with high humidity (P<0.05). We measured plant growth 24 to 52 days post-grafting to understand how leaf removal affects transplant quality, growth, and development. Plants with 90% LR had significant growth reduction at day 24 but at day 52, only had reduced stem diameter and height compared to 0% LR. Total flower count was the same for all treatments. Leaf removal during grafting may be a viable method for propagating high quality, grafted transplants.

A dissertation submitted to the Faculty of Science University of the Witwatersrand, Johannesburg for the Degree of Master of Science. Johannesburg 1992 / 1. Beder, J.B. Thornley, A.L. and Veale.R, Human keratinocyte culture techniques using foetal, neonatal and adult keratinocytes with particular reference to extensive bum wounds. This paper was presented at the South African Burn Society Biannual Congress held at Berg en Dal, Kruger National Park, from 31 August to 1 September 1989. 2. Beder, J.B., Thornley, A.L. and Veale, R. Human keratinocyte culture techniques in extensive burn wounds. The Journal of Trauma and Emergency Medicine. 1990 Jan/Feb; 7 (1); 29-32. 3. Beder J.B. Cultured allografts. A letter appearing in the Continuing Medical Education Journal (CEM). 1990 Jan; 8(1): 48. 4. Beder, J.B. Problems and attempted solutions associated with the application of cultured epidermal grafts to full thickness burns in extensively burnt patients. This paper was presented in the form of a poster at the Association of Surgeons of South Africa Biannual Congress held in Bloemfontein from May 1-4 1990. 5. Beder, J.B., Thornley, A.L., Veale R., Kadwa, A.M., Scott, E. Healing chronic leg ulcers cultured keratinocyte allografts. This paper was presented at the annual Congress of The Surgical Research Society of Southern Africa held in Bloemfontein from 29 April to 1 May 1990. This paper was the runner-up for the best paper presented at the above congress. 6. The abstract of the paper mentioned in 5. above was published in the South African Journal of Surgery 1990 Sep; 28 (3): 123. 7. Beder, J.B., Healing full thickness burns with various types of cultured epidermal grafts - a comparative study. This paper was presented at the Z4th annual meeting of the British Burn Association held at the post-graduate centre, Stock Mandeville, Aylesbury, Bucks. England, United Kingdom, on the 10th May 1991. 8. Beder, J.B, J.B. A comparative study of various keratinocyte cell lines used in the synthesis of confluent stratified keratinocyte sheets. This paper was presented at the skin culture meeting, a satellite meeting of the 24th annual meeting of the British Burn Association, held at the post-graduate centre, Stoke-Mandeville, Aylesbury, Bucks, England, United Kingdom, on the 8th May 1991. 9. Beder, J.B. Healing chronic leg ulcers using cultured keratinocyte allografts. This paper was presented at the skin culture meeting of the British Burn Association held at the post-graduate centre, Stoke- Mandeville, Aylesbury, Bucks, England, United Kingdom on the 8th May 1991. 10. Beder, J.B., Thornley, A.L. and Veale, R. Healing chronic ulcers and other skin defects, using cultured keratinocyte allografts - including an assessment of their survival. Submitted for publication to the British Medical Journal. 11. Beder, J.B. The preparation and grafting of cultured epidermal sheets. Submitted for publication to the South African Journal of Surgery. 13. Beder, J.B., Thoenley, A.L. and Veale. R. Healing full thickness burns with cultured epidermal grafts - a comparative study. Submitted for publication to Transplantation.

Dans le cadre des procédés de clarification d'eau de surface, les flocs formés au cours des étapes de coagulation et de floculation peuvent être séparés de l'eau traitée par décantation ou par flottation. Dans ce dernier cas, le procédé actuellement en vigueur est la flottation à air dissous et présente un certain nombre d'inconvénients. Ainsi, dans ce contexte, la présente thèse consiste à développer un matériau innovant, à la fois flottant et floculant, pour une application dans un procédé de flottation sans air. Dans un premier temps, l'élaboration de billes de polystyrène expansibles utilisant l'eau ou l'éthanol comme agent gonflant a été réalisée. D'autres billes ont ensuite été préparées en présence de 4-(chlorométhyl)styrène comme co-monomère puis la polymérisation par transfert d'atome amorcée en surface (SI-ATRP) de l'acrylamide a été effectuée avec succès. L'impossibilité d'expanser ces matériaux a ensuite conduit à l'exploration de nouvelles voies de synthèse avec la fonctionnalisation de matériaux flottants existants par des techniques de « grafting from » ou « grafting onto ». Quelle que soit la voie envisagée, la première étape a consisté à réduire les fonctions nitrile en amine primaire en présence d'hydrure d'aluminium lithium. Après fonctionnalisation par du bromure de bromoisobutyryle ou du chlorure d'acryloyle, il a été possible de venir greffer de l'acrylamide par SI-ATRP ou de l'amidon via un amorceur redox, respectivement. Les matériaux flottants/floculants obtenus ont été testés lors de flottatests. Les meilleurs résultats ont été obtenus avec les microsphères fonctionnalisées par de l'amidon anionique. Ces dernières ont permis d'abattre la turbidité de l'eau, ont ensuite été régénérées avec succès, par des bains d'acide oxalique ou de dithionite de sodium, et employées durant plusieurs cycles flottatest/régénération avec des résultats reproductibles. / At the end of clarification process, after coagulation-flocculation steps, flocs can be removed from treated water by settling or flotation. In the latter case, Dissolved Air Flotation is the currently used process. However, this method showed important drawbacks, especially an important energetic cost due to the production of air saturated water. In that context, the goal of the reported work dealt with achieving air-free flotation using innovative floating materials. First of all, the synthesis of expandable polystyrene beads using water or ethanol as blowing agent was investigated. Other beads containing both styrene and 4-(chloromethyl)styrene were prepared. Then, surface initiated atom transfer radical polymerization of acrylamide (SI-ATRP) was achieved. Unfortunately, the expansion of such materials was not possible. Therefore, the second part focused on the functionalization of Expancel beads by “grafting from” or “grafting onto” techniques. The first step consisted in reducing some nitrile functions at the surface into primary amine ones. After functionalization with bromoisobutyryl bromide, the SI-ATRP of acrylamide was performed in water at room temperature. On the other hand, the acryloyl chloride was grafted onto amine functions, and grafting of starch was achieved using a redox initiator. All materials obtained have been used for flocculation/flotation tests and demonstrated satisfactory performances in terms of turbidity removal. Beads functionalized with starch have been successfully regenerated with oxalic acid and sodium dithionite and kept appropriate efficiency during several flotation/regeneration cycles.

Typescript. / Digitized by Kansas Correctional Industries

Currently, extensive research in using bio‐derived polymers is being done, highlighting the importance of sustainable, green polymeric materials. Some sustainable alternatives to synthetic polymers include lignin, starch, cellulose or blends of these with petroleum‐based polymers. In New Zealand, large quantities of animal derived proteins are available at very low cost, making it ideal as a sustainable alternative to petroleum‐derived polymers. However, the processability of most proteins is very difficult, but can be improved by blending with synthetic polymers, such as polyolefins. To improve, the compatibility between these substances, a functional monomer could be grafted onto the polyolefin chain. Using an appropriate functional group, the polyolefin could then react with certain amino acids residues in the protein. Lysine and cystein are the two most appropriate amino acid residues because of their reactivity and stability at a wide pH range. In this study, free radical grafting of itaconic anhydride (IA) onto polyethylene was investigated. IA was selected because it is capable of reacting with polyethylene and amino acid residues, such as lysine. The objective of the research was to identify and investigate the effect of reaction parameters on grafting. These were: residence time, temperature, initial monomer concentration as well as peroxide concentration and type. Grafting was characterized in terms of the degree of grafting (DOG), percentage reacted and the extent of side reactions. The reaction temperature was taken above the melting point of the polyethylene, monomer and decomposition temperature of the initiator. It was found that above 160 C polymer degradation occurred, evident from sample discolouration. A higher degree of grafting can be achieved by increasing the initial monomer concentration up to a limiting concentration. The highest DOG achieved was about 1.2 mol IA per mol PE, using 2 wt% DCP. When using 2 wt % peroxide, the limiting concentration was found to be 6 wt% IA, above which no improvement in DOG was achieved. It was found that DCP is much more effective at grafting, compared to DTBP because DTBP is more prone to lead to side reactions than DCP. iv It was found that a residence time of 168 seconds resulted in the highest DOG, corresponding to 4 extrusions in series. However, it was also found that an increase in residence time resulted in an increase in polymer degradation. The tensile strength of PE decreased after two extrusions when using DTBP, and three extrusions, when using DCP. Young's modulus decreased only slightly, while all samples showed a dramatic decrease in ductility, even after one extrusion. It was concluded that degradation had a more pronounced effect on mechanical properties than cross‐linking, and residence time should therefore not exceed three extrusions in series, which corresponded to about 126 seconds. It can be concluded that a high reaction temperature and high initiator concentration lead to a low degree of grafting, accompanied by high cross‐linking and increased degradation. On the other hand, high monomer concentration and high residence time lead to a high degree of grafting. Optimising grafting is therefore a trade off between maximal DOG and minimising side reactions such as cross‐linking and degradation and optimal conditions do not necessarily correspond to a maximum DOG. Other factors, such as the use of additives to prevent degradation should also be investigated and may lead to different optimum conditions.