The primary objective of this thesis was to test the material properties of the new Grade 300, low-relaxation prestressing strand. The purpose of this testing was to verify the advertised breaking strengths and relaxation properties of the Grade 300 strand. Additional properties, such as yield strength, modulus of elasticity, and elongation, were also examined. Several tests were performed on each specific type of strand. For example, six tension and eight relaxation tests were performed on the Grade 300, 0.5 in. diameter, 0.153 square in. area strand. From the tests, it is concluded that the advertised breaking strengths and relaxation properties from Strand-Tech Martin, Inc. were accurate and meet the industry standards for low relaxation strand. The secondary objective of this project was to comment on the benefits of the Grade 300 strand as it pertains to the bridge industry. It was concluded from the tests that the Grade 300 strand had a 10 per cent larger 1 per cent elongation stress compared to the bridge industry standard Grade 270 strand. Furthermore, the amount of loss due to relaxation for the Grade 300 strand was comparative to that of the Grade 270 strand. While additional testing needs to be done to include stress-corrosion, transfer length, development length, and flexural strength, the completed testing indicates that less strand will be required using Grade 300 strand versus Grade 270 strand to achieve a set span length and transverse girder spacing. In addition, with the industry gradually progressing toward using higher strength concretes, longer span lengths and larger transverse girder spacing can be achieved by using the Grade 300 higher strength strand. The final objective of this testing was to examine the procedures and testing methods outlined by ASTM A416, Standard Specification for Steel Strand, Uncoated Seven-Wire for Prestressed Concrete (2005), ASTM E328, Standard Test Methods for Stress Relaxation for Materials and Structures (2002), and ASTM A370, Standard Test Methods and Definitions for Mechanical Testing of Steel Products (2005). The breaking strength and yield strength tables in ASTM A416 (2005) need to be updated with the new Grade 300 strand information. Based on this testing, ASTM should also remove the recommendation of simply using aluminum foil and Standard V-Grips to grip the strand. Even though the standard Grade 270 and Grade 300 regular diameter strand met the material property requirements when using aluminum foil as a cushioning material, none of these samples broke clearly within the gage length of the strand. Furthermore, all of the super area strand samples failed prematurely at the grips due to the notching effect of the V-grip teeth. Thus, an alternative method involving aluminum tubing, aluminum oxide, and epoxy were used to create a cushioning device between the V-grip and the strand in order to achieve the true ultimate breaking stress of the strand. Finally, ASTM should comment on the impact of test length on the total relaxation measurements. Three test lengths were evaluated during the 26 relaxation tests. As the test length increased, the total measured relaxation decreased. Losses due to chuck slip and frame settlement were negligible as the strand test length increased. / Master of Science

No description available.

No / Beta 2-microglobulin (ß2m) is known to form amyloid fibrils de novo in vitro under acidic conditions (below pH 4.8). Fibril formation at neutral pH, however, has only been observed by deletion of the N-terminal six residues; by the addition of pre-assembled seeds; or in the presence of Cu2+. Based on these observations, and other structural data, models for fibril formation of ß2m have been proposed that involve the fraying of the N and C-terminal ß-strands and the consequent loss of edge strand protective features. Here, we examine the role of the N and C-terminal strands in the initiation of fibrillogenesis of ß2m by creating point mutations in strands A and G and comparing the properties of the resulting proteins with variants containing similar mutations elsewhere in the protein. We show that truncation of buried hydrophobic side-chains in strands A and G promotes rapid fibril formation at neutral pH, even in unseeded reactions, and increases the rate of fibril formation under acidic conditions. By contrast, similar mutations created in the remaining seven ß-strands of the native protein have little effect on the rate or pH dependence of fibril formation. The data are consistent with the view that perturbation of the N and C-terminal edge strands is an important feature in the generation of assembly-competent states of ß2m.

No description available.

Previous modeling of wood materials has included many assumptions of unknown mechanical properties associated with the hierarchical structure of wood. The experimental validation of previous models did not account for the variation of mechanical properties present in wood materials. Little research has explored the uncertainties of mechanical properties in earlywood and latewood samples as well as wood strands. The goal of this study was to evaluate the effect of the intra-ring properties and grain angles on the modulus of elasticity (MOE) and ultimate tensile strength (UTS) of different orientation wood strands and to analyze the sensitivity of the MOE and UTS of wood strands with respect to these variables. Tension testing incorporating digital image correlation (DIC) was employed to measure the MOE and UTS of earlywood and latewood bands sampled from growth ring numbers 1-10 and growth ring numbers 11-20. A similar technique adjusted for strand size testing was also applied to measure the MOE and UTS of different orientation wood strands from the two growth ring numbers. The stochastic finite element method (SFEM) was used with the results from the earlywood and latewood testing as inputs to model the mechanical property variation of loblolly pine wood strands. A sensitivity analysis of the input parameters in the SFEM model was performed to identify the most important parameters related to mechanical response. Modulus of elasticity (MOE), Poisson ratio, and ultimate tensile strength (UTS) from earlywood and latewood generally increased as the growth ring number increased except for the UTS of latewood, which showed a slight decrease. MOE and UTS from radial, tangential, and angled grain orientation strands increased as the growth ring numbers increased while MOE and UTS from cross-grain strands decreased as the growth ring number increased. Shear modulus of wood strands increased as the growth ring number increased while shear strength decreased as the growth ring number increased. Poisson ratio from radial and angled grain strands decreased as the growth ring number increased while Poisson ratio from tangential and cross grain orientation strands increased as the growth ring number increased. The difference of average MOE from different grain strands between experimental results and SFEM results ranged from 0.96% to 22.31%. The cumulative probability distribution curves from experimental tests and SFEM results agreed well except for the radial grain models from growth ring numbers 11-20. From sensitivity analysis, earlywood MOE was the most important contributing factor to the predicted MOE from different grain orientation strand models. From the sensitivity analysis, earlywood and latewood participated differently in the computation of MOE of different grain orientation strand models. The predicted MOE was highly associated with the strain distribution caused by different orientation strands and interaction of earlywood and latewood properties. In general, earlywood MOE had a greater effect on the predicted MOE of wood strands than other SFEM input parameters. The difference in UTS between experimental and SFEM results ranged from 0.09% to 11.09%. Sensitivity analysis showed that grain orientation and growth ring number influenced the UTS of strands. UTS of strands from growth ring numbers 1-10 showed strength indexes (Xt, Yt, and S) to be the dominant factors while UTS of strands from growth ring numbers 11-20 showed both strength indexes and stress components (Ï 1, Ï 2, and Ï 12) to be the dominant factors. Grain orientations of strands were a strong indicator of mechanical properties of wood strands. / Ph. D.

Submitted by admin tede (tede@pucgoias.edu.br) on 2016-09-12T19:08:40Z No. of bitstreams: 1 KAMILLA MARRA DE MORAES.pdf: 1010513 bytes, checksum: 15f5a8d9eaef871dcf61affa2787e854 (MD5) / Made available in DSpace on 2016-09-12T19:08:40Z (GMT). No. of bitstreams: 1 KAMILLA MARRA DE MORAES.pdf: 1010513 bytes, checksum: 15f5a8d9eaef871dcf61affa2787e854 (MD5) Previous issue date: 2016-03-21 / The aim of this study is to address the contemporary poetry and its various aspects. For this there was the use of stylistic features considered classics in contemporary poetic creation. In this context the modern lyric would be the most expressive feature the presence that still resists the contemporary poetry. As a research subject were chosen three contemporary Brazilian poets: Paulo Henriques Britto by fusionismo that place between the classic and the modern; Marcos Siscar because his verse in crisis and Arnaldo Antunes with the state of poetry in motion. The poems are analyzed with the intent to identify the classic features that remain in use in contemporary poetic writing. The research aims to recognize the possible aspects of contemporary Brazilian poetry as derealization of the classic models transforming them into new artistic and poetic language. / O objetivo deste trabalho é abordar a poesia contemporânea e suas distintas vertentes. Para isso verificou-se o uso de recursos estilísticos considerados clássicos na criação poética contemporânea. Nesse contexto a lírica moderna seria o recurso mais expressivo pela presença que resiste ainda na poesia contemporânea. Como objeto de pesquisa foram escolhidos três poetas brasileiros contemporâneos: Paulo Henriques Britto pelo fusionismo que realiza entre o clássico e o moderno; Marcos Siscar, devido o seu verso em crise e Arnaldo Antunes com o estado da poesia em movimento. Os poemas são analisados com intenção de identificar quais os recursos clássicos que permanecem em uso na escritura poética contemporânea. A pesquisa visa reconhecer as possíveis vertentes da poesia contemporânea brasileira como a desrealização dos modelos clássicos transformando- os em nova linguagem artística e poética.

Submitted by Lara Oliveira (lara@ufersa.edu.br) on 2017-09-13T20:42:26Z No. of bitstreams: 1 CamiloCD_DISSERT.pdf: 2672507 bytes, checksum: d50d300dbb04da2f73d158d0ac70f5a1 (MD5) / Approved for entry into archive by Vanessa Christiane (referencia@ufersa.edu.br) on 2017-10-27T13:05:05Z (GMT) No. of bitstreams: 1 CamiloCD_DISSERT.pdf: 2672507 bytes, checksum: d50d300dbb04da2f73d158d0ac70f5a1 (MD5) / Approved for entry into archive by Vanessa Christiane (referencia@ufersa.edu.br) on 2017-10-27T13:08:25Z (GMT) No. of bitstreams: 1 CamiloCD_DISSERT.pdf: 2672507 bytes, checksum: d50d300dbb04da2f73d158d0ac70f5a1 (MD5) / Made available in DSpace on 2017-10-27T13:08:38Z (GMT). No. of bitstreams: 1 CamiloCD_DISSERT.pdf: 2672507 bytes, checksum: d50d300dbb04da2f73d158d0ac70f5a1 (MD5) Previous issue date: 2017-02-21 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Taphonomic studies reveals important information about how the environment affects the remains of organisms during the process of decaying. This approach can be used for the study of both ancient and recent organisms. The use of taphonomic techniques to study recent marine mammals were underused, despite its potential. This work aims to study bone material of marine mammals in search of marks left by post-mortem processes related to biotic and abiotic environmental factors in the northern cost of Rio Grande do Norte State, Brasil. According to the taphonomic signatures found in the bone material it was identified weathering processes, abrasion, necrophagy, breaks, taphonomic feedback and human actions. For the northern coast of Rio Grande do Norte skulls have better representation in strandings of marine mammals, but vertebrae have greater reliability for faunal survey. The dynamic tidal influences directly on the samples, acting as a carrier and modifying factor. Also according to the taphomonic signatures found the study area has great heterogeneity regarding the environmental dynamics that produce the signatures studied, adjacent areas can produce different signatures and distant areas can produce similar signatures / Estudos tafonômicos revelam informações importantes sobre como o ambiente afeta os restos de organismos durante o processo de decaimento. Esta abordagem pode ser utilizada tanto para estudo de organismos antigos, como para organismos recentes. A utilização das técnicas de tafonomia para estudo com mamíferos marinhos recentes foram pouco exploradas, apesar de seu potencial. Este trabalho objetiva estudar material ósseo de mamíferos marinhos em busca de marcas deixadas por processos post-mortem relacionados aos fatores ambientais bióticos e abióticos no litoral setentrional do Rio Grande do Norte, Brasil. De acordo com as assinaturas tafonômicas encontradas no material ósseo foi possível identificar processos de intemperismo, abrasão, necrofagia, quebras, retroalimentação tafonômica e ações antrópicas. Para o litoral setentrional do Rio Grande do Norte os crânios possuem uma melhor representação nos encalhes de mamíferos marinhos, porém nota-se que as vértebras possuem maior fidedignidade para levantamento faunístico. A dinâmica das marés influencia diretamente nas amostras, servindo como fator transportador e modificador. Ainda de acordo com as assinaturas tafonômicas encontradas nota-se que a área de estudo possui grande heterogeneidade quanto às dinâmicas ambientais que produzem as assinaturas estudadas, áreas adjacentes podem produzir assinaturas diferentes e áreas distantes podem produzir assinaturas semelhantes / 2017-09-13

Corrosion of steel tendons is a major problem for post-tensioned concrete, especially because corrosion of the steel strands is often hard to detect inside grouted ducts. Non-metallic tendons can serve as an alternative material to steel for post-tensioning applications. Carbon fiber reinforced polymer (CFRP), given its higher strength and elastic modulus, as well as excellent durability and fatigue strength, is the most practical option for post-tensioning applications. The primary objective of this research project was to assess the feasibility of the use of innovative carbon fiber reinforced polymer (CFRP) tendons and to develop guidelines for CFRP in post-tensioned bridge applications, including segmental bridges and pier caps. An experimental investigation and a numerical simulation were conducted to compare the performance of a scaled segmental bridge model, post-tensioned with two types of carbon fiber strands and steel strands. The model was tested at different prestress levels and at different loading configurations. While the study confirms feasibility of both types of carbon fiber strands for segmental bridge applications, and their similar serviceability behavior, strands with higher elastic modulus could improve structural performance and minimize displacements beyond service loads. As the second component of the project, a side-by-side comparison of two types of carbon fiber strands against steel strands was conducted in a scaled pier cap model. Two different strand arrangements were used for post-tensioning, with eight and six strands, respectively representing an over-design and a slight under-design relative to the factored demand. The model was tested under service and factored loads. The investigation confirmed the feasibility of using carbon fiber strands in unbonded post-tensioning of pier caps. Considering both serviceability and overload conditions, the general performance of the pier cap model was deemed acceptable using either type of carbon fiber strands and quite comparable to that of steel strands. In another component of this research, creep stress tests were conducted with carbon fiber composite cable (CFCC). The anchorages for all the specimens were prepared using a commercially available expansive grout. Specimens withstood 95% of the guaranteed capacity provided by the manufacturer for a period of five months, without any sign of rupture.

No description available.

Hybridization of two or more DNA or RNA strands is well documented for the process taking place with all strands free in solution or when one strand is immobilized on a substrate. This study contributes to the investigation of the hybridization process when two single DNA strands (ssDNA) are in close proximity. We took advantage of an X sensor in which hybridization of four DNA strands enables the formation of a DNA four-way junction (crossover or X) structure. We immobilized multiple layers of crossover structures to study its hybridization being triggered by short ssDNA coming from solution and further investigate how many layers of these structures can hybridize by the addition of only one ssDNA (called input). Using a molecular beacon as reporter, we combined crossover DNA strands that recognize the reporter sequence at one side and at the other, the sequence of its input or downward crossover layer. Fluorescent signal was detected by separation of the molecular beacon’s fluorophore and quencher, as it hybridizes with the system of layers. Immobilization of the X structures into the scaffold proved to increase their communication, in comparison to being free in solution. This evidence gives us significant information for the communication of hybridized layers in a localized system, showing a promising standard for development of multilayered logic gates. The potential of these crossover DNA strands using X structure include applications in the future of biological systems, nanotechnology, and target DNA recognition for its ability to quickly recognize a signal and propagate it through extended DNA nanostructure in a controlled manner.