Thesis (Ph. D.)--University of Wisconsin--Madison, 1970. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

Membranous tubules are very abundant structures in living cells and form or are part of most intracellular organelles. The Golgi apparatus is mainly formed by tubules, which adopt different geometries and conformations. However, their physiological role has not yet been established and this is mainly due to the almost absolute lack of knowledge about the biochemical mechanisms regulating their formation, maintenance and disruption. The aim of this thesis was to investigate in a systematic way these mechanisms. The first step has been to set up an in vitro morphological assay suitable for the visualisation of Golgi-associated tubules in isolated Golgi stacks. This assay was based on electron microscopy and specifically on negative staining of whole-mount preparations. It allowed both qualitative and quantitative analysis of the morphological changes of Golgiassociated tubules after in vitro incubations. This assay was then used for screening several molecules or experimental conditions for their effect on tubular homeostasis. Among them, the most significant was BARS (BFA-dependent ADP-Ribosylation Substrate), a protein previously implicated in the maintenance of Golgi architecture. BARS has been found to cause the selective breakdown of the tubular part of the Golgi complex promoting fission events which convert the tubular structures into clusters of vesicles. This effect correlated with the enzymatic activity of BARS, which acts as an acyl-CoA dependent lysophosphatidic acid acyl transferase (LPAAT), increasing phosphatidic acid (PA) levels in Golgi membranes. This suggests that local modifications of the composition of the lipid bilayer is a possible mechanism for the fission of membranous tubules.

The composite FRP rebars research at Oregon State University was initiated in 1993 principally to develop a non-metallic hollow reinforcement. It was recognized that the tensile properties of such reinforcement are unquestionably superior to steel, but its performance in concrete could be problematic. The bond between FRP rebars and concrete was identified as a critical area of concern. The purpose of this study is (i) to analyze a variety of FRP and steel reinforcing units; (ii) to advance the knowledge of bond mechanism, failure modes, and parameters influencing the bond strength; (iii) to compare composite rebars to conventional steel and to assess their applicability as reinforcing members. Commercially available FRP rebars were investigated. Particular emphasis was given to a hollow glass FRP rod designed at Oregon State University. Several parameters were investigated, including: failure mode, concrete compressive strength, rebar diameter and circumference/cross section ratio, embedment length, concrete cover, and microstructure of the composite rebars. It was recognized that the ASTM C234-90 pull-out standard is test of concrete strength. Therefore a modified pull-out test was developed for evaluating the bond strength behavior. A newly developed European bond test procedure was compared with locally modified version of the pull-out method. The new procedure was used for the first time in the United States. The study demonstrated a phenomenon, not reported in the published research at this time, defined as a size effect. The size effects result in lower bond strength with increasing area of the interface between FRP bars and concrete. The next phase of the research was dedicated to the hollow glass FRP rebar. The goal was to compare its bond properties to conventional steel and solid FRP bars. The study led to two new phenomena not described in the literature previously. Results showed that the concrete compressive strength does not significantly affect the bond strength. This observation was in contradiction with the bond strength theory which considers the concrete strength as major variable. The second observation revealed significant difference in bond performance between bars with different microstructures. It is recommended that microstructure of the FRP bars be considered as a variable when investigating bond strength. / Graduation date: 1998

Thesis (M.M.)--Bowling Green State University, 2007. / Document formatted into pages; contains vi, 52 p. : ill. Includes bibliographical references.

The parallel bars is used in physical therapy and is mainly used for patients who have to train walking and balance after a stroke or an operation. It consists of two long handrails with two legs on each handrail. These legs go down into two ground-plates and are locked at the wanted height with a pin. The parallel bars is an appreciated device and is used on a daily basis in many care units. The main issue with the manual parallel bars is that it is very difficult and heavy for a single person to adjust the height of it. If a larger adjustment of the height has to be done, the legs have to be adjusted one at a time otherwise the they will be locked. Often the height isn’t adjusted after every single patient because it’s so difficult and therefore the training doesn’t get optimal for patient. The purpose with this project has been to find a solution that makes the height easier to adjust, so that the parallel bars will be adjusted after each patient. Our goal was to develop and produce a functional prototype of the solution. The result was Levo which is a lifting device that complements the parallel bars. Levo is a simple product to handle and has wheels which makes it easy to move around. To adjust the height of the parallel bars with Levo, place Levo in the middle of the handrail and press the button. The handrail will go up and the button can be released when the right height is reached. To lower the handrail, press the button and push the handrail down. Release the button when it has reached the wanted height. Levo has a construction which makes it possible to use as a complement to almost every manual parallel bars on the market. For a product to be used in care units it has to meet special demands. To know which demands and what properties Levo had to fulfill to be a product that physiotherapists could use and wanted in their work, we contacted several physiotherapists. For example the product could not have any sharp edges and had to be easy to clean. The product also had to be easy and fast to use when the height of the parallel bars should be adjusted. The physiotherapists point of view was in consideration during the developing process of Levo and many different solutions was compared to find an optimal solution that fulfilled all the demands. / Den manuella gåbarren är ett hjälpmedel inom sjukgymnastiken för att träna patienter i gång och balans. Barren är uppbyggd av två långa ledstänger med två ben på vardera ledstång. Dessa ben sitter fast i varsin bottenplatta som håller ihop barren på bredden och hindrar den från att välta. Gåbarren är ett uppskattat hjälpmedel och används på de flesta sjukgymnastikenheter inom sjukvården i Sverige. För att kunna reglera höjden på ledstängerna efter patientens behov behöver vårdpersonalen lösgöra benen i bottenplattan samt lyfta ledstången till önskat läge för att sedan låsa benet i det läget. När barren behöver justeras flera höjdlägen behöver arbetet göras stegvis på alla ben då benen annars låser sig för varandra. Eftersom arbetet med att justera höjden på barren är tungt och tidskrävande slarvas det ofta med att anpassa höjden efter varje patient. Detta i sin tur kan bli ett problem för patienten som inte får en optimal träning i barren. Syftet med projektet är att hitta en lösning till problemet med höjdjusteringen som gör det enkelt för vårdpersonalen att justera höjden för varje patient. Målet är att ta fram en fungerande prototyp på lösningsförslaget. Resultatet blev produkten Levo som är en separat lyftanordning till gåbarren. Levo är en smidig och lättanvänd produkt som är enkel att flytta till barren då den har hjul. Levo används genom att den placeras under barrens ena ledstång och höjden på Levo justeras med hjälp av en knapp. Önskas ledstången att höjas hålls knappen inne tills rätt höjdnivå uppnås. Skall ledstången sänkas hålls knappen inne tills rätt höjd har nåtts samtidigt som personen trycker ner ledstången. Fördelen med Levo är att den utför det tunga arbetet med att lyfta barren, samtidigt som den inte är i vägen för patienten eftersom den enkelt kan flyttas undan efter användning. Den har inget behov av eluttag eller liknande eftersom lyftmekanismen i är en gasfjäder som inte kräver någon skötsel. Under arbetet med att ta fram Levo intervjuades sjukgymnaster för att få en uppfattning om vilka egenskaper och krav som produkten behöver uppfylla för att den ska få användas inom sjukvården, samt vara tilltalande för personalen. Den får till exempel inte ha vassa kanter och måste vara lätt att rengöra. En annan viktig del är att den måste vara lätt att använda och det skall gå snabbt att justera höjden på barren med den, annars är risken stor att den inte användas. Detta togs hänsyn till under framtagningen av Levo där flera olika typer av lyftmekanismer jämfördes för att hitta en optimal lösning som uppfyllde sjukgymnasternas krav.

Glassy polymers are extensively used to make all kinds of structural components. Polymers, such as epoxies, are often chosen as matrices in polymer matrix composites (PMC). Ever since the 1960s, these types of composites have been gaining importance in aerospace and automotive advanced applications due to their high sti ness and weight saving potential. In order to provide clues on the dependence of the fracture behavior upon the stress triaxiality, a series of tensile tests on epoxy (Epon862) round notched bars were carried out at NASA Glenn Research Center. Using state-of-the-art non-contact dig- ital image correlation measurement technique, the mechanical quantities of interest were extracted in order to understand how the fracture behavior responds when sub- jected to various levels of stress triaxiality induced by varying the notch radius of the specimens. E ects of aging on the fracture behavior were also investigated. A physics-based macromolecular constitutive model that accounts for temperature and pressure sensitivity as well as small-strain softening and large-strain hardening was used to model the deformation behavior. Good correlation between experiments and numerical simulations was achieved. To predict fracture, a pressure-sensitive model motivated by previous work is introduced. Based on the experimental and numerical results, the relation between the mean strain to failure versus the stress triaxiality was de ned and it was shown that the fracture response of the material is strongly a ected by the level of stress triaxiality.

Thesis (M.S.)--West Virginia University, 2001. / Title from document title page. Document formatted into pages; contains x, 138 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 125-129).

published_or_final_version / Geography and Geology / Doctoral / Doctor of Philosophy

Bathymetric features such as nearshore sandbars can alter local nearshore hydrodynamic processes such as the production of infragravity energy. These bathymetric features may act to reduce or increase the amount of infragravity energy that reaches the shoreline. To determine the influence of the bathymetric features on infragravity energy, the numerical nearshore processes model XBeach was used to simulate infragravity energy at the shoreline. Numerical simulations were completed for three types of bathymetric scenarios: continuous alongshore bar, bar-rip, and no-bar. The presence of the bar reduces the amount of infragravity energy at the shoreline when compared with the no-bar scenario. This reduction was characterized by modifying an empirical parameterization for significant infragravity swash developed by Stockdon et al. (2006) for barred beaches. Results show that the amount of infragravity energy in the form of swash is dependent on the bar height and depth, in addition to the offshore wave height and wavelength. The bar-rip bathymetry produces significant alongshore variation in infragravity energy. The alongshore variations may be due to refracted wave energy or the production of an edge wave by the rip. The magnitude of infragravity energy in the alongshore direction is found to be correlated with the surf zone width. Finally, erosion for the bar-rip scenario is studied qualitatively. The shape of the shoreline is modified during storm events, and is found to take the shape of the alongshore distribution of infragravity energy. Since infragravity swash influences beach erosion, results of this research may be used as part of an erosion vulnerability scale. Such information on erosion vulnerability is important for the design of coastal protection systems and the protection of coastal communities.

The behavior of concrete members reinforced with fiber reinforced polymer (FRP) bars has been the focus of many studies in recent years. Nowadays, several codes and design guidelines are available for the design of concrete structures reinforced with FRP bars under flexural and shear loads. Meanwhile, limited research work has been conducted to examine the axial behavior of reinforced concrete (RC) columns with FRP bars. Due to a lack of research investigating the axial behavior of FRP reinforced concrete columns, North American codes and design guidelines do not recommend using FRP bars as longitudinal reinforcement in columns to resist compressive stresses. This dissertation aims at evaluating the axial performance of RC compression members reinforced with glass FRP (GFRP) and carbon FRP (CFRP) bars and stirrups through experimental and analytical investigations. A total of twenty seven full scale circular RC specimens were fabricated and tested experimentally under concentric axial load. The 300 mm diameter columns were designed according to CAN/CSA S806-12 code requirements. The specimens were divided to three series; series I contains three reference columns; one plain concrete and 2 specimens reinforced with steel reinforcement. Series II contains 12 specimens internally reinforced with GFRP longitudinal bars and transverse GFRP stirrups, while series III includes specimens totally reinforced with CFRP reinforcement. The experimental tests were performed at the structural laboratory, Faculty of Engineering, University of Sherbrooke. The main objective of testing these specimens is to investigate the behavior of circular concrete columns reinforced with GFRP or CFRP longitudinal bars and transverse hoops or spirals reinforcement. Several parameters have been studied; type of reinforcement, longitudinal reinforcement ratio, the volumetric ratios, diameters, and spacing of spiral reinforcement, confinement configuration (spirals versus hoops), and lap length of hoops. The test results of the tested columns were presented and discussed in terms of axial load capacity, mode of failure, concrete, longitudinal, and transverse strains, ductility, load/stress-strain response, and concrete confinement strength through four journal papers presented in this dissertation. Based on the findings of experimental investigation, the GFRP and CFRP RC columns behaved similar to the columns reinforced with steel. It was found that, FRP bars were effective in resisting compression until after crushing of concrete, and contributed on average 8% and 13% of column capacity for GFRP and CFRP RC specimens, respectively. Also, the use of GFRP and CFRP spirals or hoops according to the provisions of CSA S806-12 yielded sufficient restraint against the buckling of the longitudinal FRP bars and provided good confinement of the concrete core in the post-peak stages. The axial deformability (ductility) and confinement efficiency can be better improved by using small FRP spirals with closer spacing rather than larger diameters with greater spacing. It was found that, ignoring the contribution of FRP longitudinal bars in the CAN/CSA S806-12 design equation underestimated the maximum capacity of the tested specimens. Based on this finding, the design equation is modified to accurately predict the ultimate load capacities of FRP RC columns. New factors ?[indice inférieur g] and ?[indice inférieur c] were introduced in the modified equation to account for the GFRP and CFRP bars compressive strength properties as a function in their ultimate tensile strength. On the other hand, proposed equations and confinement model were presented to predict the axial stress-strain behavior of FRP RC columns confined by FRP spirals or hoops. The model takes into account the effect of many parameters such as; type of reinforcement, longitudinal reinforcement ratio; transverse reinforcement configuration; and the volumetric ratio. The proposed model can be used to evaluate the confining pressure, confined concrete core stress, corresponding concrete strain, and stress-strain relationship. The results of analysis using the proposed confinement model were compared with experimental database of twenty four full-scale circular FRP RC columns. A good agreement has been obtained between the analytical and experimental results. Proposed equations to predict both strength and stress-strain behavior of confined columns by FRP reinforcements demonstrate good correlation with test data obtained from full-scale specimens.