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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

Single-molecule diffusion measurements for material characterization in one-dimensional nanostructured polymer films

Tran-Ba, Khanh-Hoa January 1900 (has links)
Doctor of Philosophy / Department of Chemistry / Takashi Ito / This dissertation describes single-molecule tracking (SMT) measurements for the quantitative characterization of one-dimensional (1D) nanostructures in 200 nm-thick surfactant-templated mesoporous silica (STMS) and cylinder-forming polystyrene-poly(ethylene oxide) diblock copolymer (CF-PS-b-PEO) films with a μm-scale thickness. SMT is advantageous for the characterization of nanomaterials over conventional methods because it permits the simultaneous and quantitative assessment of the nanoscale and microscale morphologies, and mass-transport properties of the materials with a high nanometer-scale resolution under ambient conditions. It offers a unique means for the assessment and evaluation of the μm-scale nanostructure alignment in polymer films induced by vertical spin-coating (for STMS films), directional solution flow and solvent-vapor penetration (SVP) methods (both for CF-PS-b-PEO films), highly crucial for many potential technological applications using the materials. Through this work, we have identified suitable sample preparation conditions (e.g. solvent, temperature or solution flow rate) for obtaining highly-ordered mesoporous and microdomain structures over a long-range (> 5 μm). For the quantitative assessment of the 1D SMT data, orthogonal regression analysis was employed, providing assessment of the in-plane orientation and size of individual nanostructures with nanometer-scale precision. The analysis of the 1D trajectory data allowed the radius (ca. 11 nm) of cylindrical PEO microdomains to be estimated, yielding results consistent with the AFM results (ca. 14 nm). The distribution of the trajectory angles offered the estimation of the average orientation and order of the nanostructures in domains/grains for a μm-wide region of the polymer films, revealing the higher efficiency of SVP in the nanostructure alignment as compared to the spin coating and solution flow approaches. Systematic SMT measurements across the film depth and along lateral mm-scale distances afforded valuable insights into the shear- and solvent-evaporation-based alignment mechanisms induced by solution flow and SVP/spin coating approaches, respectively. Fluorescence recovery after photobleaching (FRAP) measurements in a SVP-aligned CF-PS-b-PEO film permitted the longer-range mass-transport properties to be probed, reflecting the effective continuity of the aligned cylindrical nanostructures over > 100 μm in length. In this dissertation, FRAP and more importantly SMT methods have provided a unique and useful means for the in-depth characterization of morphology and mass-transport characteristics in thin polymer films under ambient conditions, in confined spaces, and with a nanometer-scale resolution.
2

“Welcome to my unlikely existence” : En kvantitativ dataanalys av incel-forumet incels.net

Kjaer, Elvira, Fröberg, Hanna January 2020 (has links)
Syftet med studien har varit att studera onlineforumet incels.net för att undersöka huruvida medlemmarna vid forumet har liknande bakgrund och/eller gemensamma erfarenheter. Detta undersöktes med hjälp av på förhand utvalda variabler baserade på risk- och skyddsfaktorer tagna från riktlinjer inom socialtjänsten. Tidigare forskning har kunnat kartlägga en specifik rådande diskurs bland incels och uttryck av psykisk ohälsa hos gruppen men inte kunnat visa på gemensamma erfarenheter på kvantitativ nivå. Studien använder sig av en kvantitativ dataanalys som metod. Den vetenskapsteoretiska utgångspunkten för studien är kritisk realism, social exkludering och stämplingsteori. I diskussion av resultaten har social exkludering och stämplingsteori använts. Studien utfördes genom granskning av totalt 12 700 inlägg på online-forumet incels.net. I studien ingick granskning av 111 medlemmar på onlineforumet incels.net. Dessa medlemmars inlägg granskades för att sedan föras in i ett statistiskt sammanställt ark för att se vilka variabler som uppfylldes av vardera medlem. Det insamlade materialet undersöktes sedan genom olika typer av statistiska analyser såsom korstabulering med Chi2-test och korstabeller för att kunna urskilja samband. Vid utförandet av de statistiska jämförelserna användes programmet Statistical Package for the Social Sciences (SPSS). Resultatet av studien visade på en förhöjd andel psykisk problematik hos medlemmarna på forumet vilket sedan diskuterades och jämfördes med övrig befolkning. Resultatet visade även på ett samband mellan dåliga familjeförhållanden och psykisk problematik hos medlemmarna på incels.net.
3

An Examination of Relationships Between Exposure to Sexually Explicit Media Content and Risk Behaviors: A Case Study of College Students

Stana, Alexandru 20 December 2013 (has links)
No description available.

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