Theses (M.S.)--Marshall University, 2006. / Title from document title page. Includes abstract. Document formatted into pages: contains vi, 77 p. Bibliography: p. 74-77.

Thesis (Ph. D.)--Lehigh University, 2000. / Includes vita. Includes bibliographical references (leaves 16-18, 45-46, 119-120, 170-171, 253).

The bulk polymerization of vinyl chloride is still at the present time far from being well understood. In spite of the economic importance of the process, the detailed quantitative behavior of the reactor has not been elucidated. Immediate reasons for this, are given by the physical complexities of particle formation (arising from oligomer precipitation in solution), and heterogeneous polymerization kinetics, recalling that the process starts with one liquid monomer phase and finishes with three phases: liquid and gaseous monomer, and solid polymer.

Organosulfur plays a significant role in synthetic chemistry. In particular α,β-unsaturated sulfides (i.e. vinyl sulfides) are versatile building blocks that exhibit untapped potential in reaction development. This thesis focuses on reaction development in this space. Chapter 1 discusses the characteristics that sulfur attributes to organic molecules followed by a review of synthetic preparations and applications of vinyl sulfides. Chapter 2 discusses the development of a formal-phosphorus Pummerer reaction enabling simple access to thiophosphonium Wittig reagents. These thiophosphonium salts are used to access a library of vinyl sulfide substrates that are further hydrolyzed to the corresponding ketones. This two-step sequence enables a strategic approach affording aldehyde to ketone homologation via vinyl sulfide intermediates, enabling access to synthetically challenging α-aryl ketones. Chapter 3 discusses the direct use of vinyl sulfides as carbonyl surrogates in Fischer indole reactions. Vinyl sulfides are demonstrated to be aldehyde and ketone surrogates in the preparation of diverse 3-substituted and 2,3-disubstituted indoles or azaindoles. The utility of this chemistry is shown with the preparations of three biologically significant compounds: 4-aza-melatonin, a furoindoline scaffold and an indomethan-like CRTh2 anatagonist. Chapter 4 showcases the first total synthesis of a chromane natural product isolated from Cassia fistula: 1-(3,4-dihydro-5-meth- oxy-2,2-dimethyl-2H-chromen-7-yl)propan-2-one. The preparatory route of this natural product features two synthetic methods developed by the Magolan group, including the aldehyde to ketone homologation described in Chapter 2. The five-step total synthesis affords the natural product in 24% overall yield and includes an efficient one-pot three-transformation sequence. Chapter 5 highlights ongoing and future projects that build on the research described in this thesis. This includes investigations into stable intermediates that facilitate access to aldehydes from vinyl sulfides. Plans are proposed to develop controlled stereoselective use of thiophosphonium reagents. Further collaborative work is discussed employing vinyl sulfides as substrates for valuable atropoisomeric heterocyclic scaffolds. / Thesis / Doctor of Philosophy (PhD)

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Each year the rate of slip and fall accidents increases among older individuals. Most falls among the elderly occur indoors rather than outdoors, and of the falls that occur in the residential home, over 600,000 are due to floor covering materials. In particular, carpet and vinyl are common floor coverings used in the home today as the elderly often transition from carpet to vinyl and vice versa. When transitioning between two different floor surfaces, older adults may adjust their gait to avoid a slip, trip, or fall. Many studies have assessed gait parameters of elderly individuals on either carpet or vinyl. Yet, few have studied the effect of transitioning between two different floor surfaces on the gait of older individuals. This study investigated the effect of transitioning between different floor coverings on the gait characteristics of the elderly. For this study, 14 elderly (65 years old and over) and 14 young (18 to 35 years old) individuals participated. All participants walked on different transitional floors, namely carpeted floors, vinyl floors, and floors covered with both vinyl and carpet. While the participants were walking on the walkway, different gait parameters were measured, including the required coefficient of friction, stride length, transitional acceleration of the whole body center-of-mass (COM), heel velocity at heel contact, perception of slipping/tripping, and toe clearance. It was hypothesized that older participant's gait parameters would be different from their younger counterparts. Also, the older participant's gait adaptation would increase the likelihood of a slip and trip propensity while transitioning between different floor surfaces compared to the younger participants. More specifically, for the elderly, transitioning from carpeted floor surfaces to vinyl floor surfaces would increase the slip propensity and transitioning from vinyl floor surfaces to carpeted floor surfaces would increase trip propensity, and therefore increase the likelihood of fall accidents. In the present study, it was found that elderly individuals had greater toe clearance than their younger counterparts. Also, the elderly individuals had smaller toe clearance on the carpet than on the vinyl, which would increase the probability of a trip-induced fall when walking on the carpet. Further, the propensity of a slip-induced fall accident increased on the vinyl shortly after transitioning from the carpet to the vinyl due to the slower transitional acceleration of the whole body COM and the increased friction demand, especially during the toe-off phase of the gait cycle, rather than heel contact phase of the gait cycle. In addition, it was also found that an increase in heel contact velocity and step length increases the propensity of a slip-induced fall accident. Furthermore, this propensity is greater while transitioning from a carpet to a vinyl floor surface, especially for elderly individuals. The results of the present study indicate that transitioning between different floor surfaces changes the biomechanical parameters of gait, especially for the elderly individuals. Although the increased likelihood of a slip or trip accident was found throughout the changes in biomechanical gait parameters, the elderly individuals who participated in this study did not perceive of slipping and tripping much. Therefore, elderly individuals should be made aware of / Master of Science

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Thesis (Ph. D.)--School of Civil and Environmental Engineering, Georgia Institute of Technology, 2004. Directed by Frank E. Löffler. / Vita. Includes bibliographical references (leaves 182-200).