Part I: A motion capture algorithm for reconstruction of supercoiled DNA Part II: Experimental and FEA-based assessment of damage mechanism in EPDM roofing structures subjected to hailstone impact

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2017-08

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Abstract

Two distinctly different research projects were performed, the results of which form the body of this manuscript. In Part I, an algorithm for characterizing the mo- tion of Supercoiled DNA is described. In Part II, the mechanism of hailstone damage on EPDM material in unveiled. Part I: ”A Motion Capture Algorithm for Reconstruction of Supercoiled DNA” Several experimental techniques have been used to study the properties of DNA. At the single molecule level, microscopy techniques have been very useful in resolving both primary and secondary structures in DNA. These microscopy techniques utilize such tools as electron beams (electron microscopy), nano-sized cantilevered probes (atomic force microscopy), flourescence (flourescence microscopy) to determine these structures in DNA. Atomic force microscopy (AFM), scanning tunneling microscopy (STM), cryo-electron microscopy (cryoEM), and the conventional electron microscopy (EM) have been useful in imaging the structure of DNA during cell processes. While the imaging techniques enable the static structure of DNA to be viewed at very high resolution, they have one common shortcoming; that it is necessary for DNA to be immobilized in order for imaging to be carried out. This eliminates the possibility of observing the dynamic response of DNA during the cell processes of interest. This emphasizes the need for the development of a technique for studying the dynamic response of DNA. This work aimed to propose a computational tool for detecting fluorophore ar- rangements, which were subsequently employed to reconstruct DNA supercoil dy- namics between fluorophores and sequential super resolution images.To achieve this goal, the arrangement and spacing of fluorophores around circular DNA must be first determined. The specific objective of this research was to develop and demonstrate an algorithm to detect the arrangement of fluorophores around circular DNA from their individual trajectories through time. Part II: ”Experimental and FEA-Based Assessment of Damage Mechanism in EPDM Roofing Structures Subjected to Hailstone Impact” Hail damage to roof assemblies within the United States and worldwide results in millions of dollars of economic loss each year. Ethylene Propylene Diene Monomer (EPDM) is a common material used in commercial applications for covering the ex- terior surface of flat roof assemblies. The purpose of this research was to conduct an experimental and numerical study of hail impact on EPDM-covered roof assemblies in order to identify conditions that could result in functional damage to the roofing structure occurs. To better understand the mechanism of damage by hailstone impact, the LS- DYNA explicit dynamics code was employed to simulate hailstone impact on a mul- tilayer EPDM roofing system. A Smooth Particle Hydrodynamics approach (SPH) was selected to represent the hailstone geometry, while a 4 layer structure consisting of plywood, insulation, gypsum board and EPDM was used to represent a typical roofing assembly. It was found that stresses and strains sustained by hail impact can, in some instances, create conditions that are conducive to failure of EPDM and its supporting layers, or at a minimum, leave the EPDM in a state which makes it susceptible to functional damage as a result of future hailstone impacts. It was also found that the integrity of the board layer supporting the EPDM membrane, plays an essential role in structural integrity of the roofing system.

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Keywords

DNA, Fluorescent microscopy, Traveling salesman problem, EPDM, Hail, Gypsum board

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