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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Tensile, rheological and morphological characterizations of multi-walled carbon nanotube/polypropylene composites prepared by microinjection and compression molding

Ezat, G.S., Kelly, Adrian L., Youseffi, Mansour, Coates, Philip D. 07 April 2022 (has links)
Yes / Polypropylene (PP) reinforced with 2 and 4 wt% of multi-walled carbon nanotubes (MWNT) were melt-blended in twin screw extruder and then molded by compression or micromolding process. The impact of injection speed on the surface morphology, rheological and tensile characteristics was investigated by using a scanning electron microscope, parallel plate rheometry, and tensiometry. Results showed that the tensile properties of micro-molded specimens were remarkably higher than those of the compression molded sheets. Compared to compression molded sheets, micromolded specimens demonstrated up to 40 and 244% higher tensile stiffness and yield strength, respectively, most likely due to the alignment of polymer chain segments in the flow direction induced during the micromolding process. It was observed that the fast filling speed caused a drop in the tensile properties of the nanocomposites and polymer. Rheological examination revealed that the presence of a rheological percolation network in the nanocomposites produced by micromolding and the fast injection speed was beneficial for establishing the percolated network. Morphological examination revealed that the size of nanotube agglomerations that appeared in micromolded specimens was up to five times smaller than in compression molded sheets and the agglomeration size decreased with the increase of the injection speed.
2

In Vitro Molecular Modification of Human Cultured and Primary Cells Using Lance Array Nanoinjection

Sessions, John W 01 March 2016 (has links)
Fundamentally altering cellular function at a genetic level is a major area of interest in the biologic sciences and the medical community. By engineering transfectable constructs that can be inserted to dysfunctional cellular systems, scientists can mitigate aberrant genetic behavior to produce proper molecular function. While viral vectors have been a mainstay in the past, there are many limitations, particularly related to safety, that have changed the focus of genome editing to incorporate alternative methods for gene delivery. Lance Array Nanoinjection (LAN), a second-generation microfabricated transfection biotechnology, is one of these alternative technologies. LAN works by utilizing both simultaneous electrostatic interaction with molecular loads and physical lancing of hundreds of thousands of target cell membranes. The purpose of this work is to demonstrate LAN in the context of in vitro transfection of immortalized culture cells and primary cells. As part of that exploration, three distinct areas of investigation are considered, which include: characterizing environmental factors that impact LAN transfection, demonstrating LAN genetic modification of immortalized HeLa 229 culture cells using an indicator marker, and lastly, investigating the effects of LAN on human primary, neonatal fibroblasts.

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