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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.
491

Self-assembled Lipid Tubules: Structures, Mechanical Properties, And Applications.

Zhao, Yue 01 January 2007 (has links)
Self-assembled lipid tubules are particularly attractive for inorganic synthesis and drug delivery because they have hollow cylindrical shapes and relatively rigid mechanical properties. In this thesis work, we have synthesized lipid tubules of 1,2-bis(tricosa-10,12-dinoyl)-sn-glycero-3-phosphocholine (DC8,9PC) by self-assembly and polymerization in solutions. We demonstrate for the first time that both uniform and modulated molecular tilt orderings exist in the tubule walls, which have been predicted by current theories, and therefore provide valuable supporting evidences for self-assembly mechanisms of chiral molecules. Two novel methods are developed for studying the axial and radial deformations of DC8,9PC lipid tubules. Mechanical properties of DC8,9PC tubules are systematically studied in terms of persistence length, bending rigidity, strain energy, axial and radial elastic moduli, and critical force for collapse. Mechanisms of recovery and surface stiffening are discussed. Due to the high aspect ratio of lipid tubules, the hierarchical assembly of lipid tubules into ordered arrays and desired architectures is critical in developing their applications. Two efficient methods for fabricating ordered arrays of lipid tubules on solid substrates have been developed. Ordered arrays of hybrid silica-lipid tubes are synthesized by tubule array-templated sol-gel reactions. Ordered arrays of optical anisotropic fibers with tunable shapes and refractive indexes are fabricated. This thesis work provides a paradigm for molecularly engineered structures.
492

Binary Geometric Transformer Descriptor Based Machine Learning for Pattern Recognition in Design Layout

Treska, Fergo 13 September 2023 (has links)
This paper proposes a novel algorithm in pixel-based pattern recognition in design layout which offers simplicity, speed and accuracy to recognize any patterns that later can be used to detect problematic pattern in lithography process so they can be removed or improved earlier in design stage.:Abstract 1 Content 3 List of Figure 6 List of Tables 8 List of Abbreviations 9 Chapter 1: Introduction 10 1.1 Motivation 10 1.2 Related Work 11 1.3 Purpose and Research Question 12 1.4 Approach and Methodology 12 1.5 Scope and Limitation 12 1.6 Target group 13 1.7 Outline 13 Chapter 2: Theoretical Background 14 2.1 Problematic Pattern in Computational Lithography 14 2.2 Optical Proximity Effect 16 2.3 Taxonomy of Pattern Recognition 17 2.3.1 Feature Generation 18 2.3.2 Classifier Model 19 2.3.3 System evaluation 20 2.4 Feature Selection Technique 20 2.4.1 Wrapper-Based Methods 21 2.4.2 Average-Based Methods 22 2.4.3 Binary Geometrical Transformation 24 2.4.3.1 Image Interpolation 24 2.4.3.2 Geometric Transformation 26 2.4.3.2.1 Forward Mapping: 26 2.4.3.2.2 Inverse Mapping: 27 2.4.3.3 Thresholding 27 2.5 Machine Learning Algorithm 28 2.5.1 Linear Classifier 29 2.5.2 Linear Discriminant Analysis (LDA) 30 2.5.3 Maximum likelihood 30 2.6 Scoring (Metrics to Measure Classifier Model Quality) 31 2.6.1 Accuracy 32 2.6.2 Sensitivity 32 2.6.3 Specifity 32 2.6.4 Precision 32 Chapter 3: Method 33 3.1 Problem Formulation 33 3.1.1 T2T Pattern 35 3.1.2 Iso-Dense Pattern 36 3.1.3 Hypothetical Hotspot Pattern 37 3.2 Classification System 38 3.2.1 Wrapper and Average-based 38 3.2.2 Binary Geometric Transformation Based 39 3.3 Window-Based Raster Scan 40 3.3.1 Scanning algorithm 40 3.4 Classifier Design 42 3.4.1 Training Phase 43 3.4.2 Discriminant Coefficient Function 44 3.4.3 SigmaDi 45 3.4.4 Maximum Posterior Probability 45 3.4.5 Classifier Model Block 46 3.5 Weka 3.8 47 3.6 Average-based Influence 49 3.7 BGT Based Model 50 Chapter 4: Results 55 4.1 Wrapper and Average-based LDA classifier 55 4.2 BGT Based LDA with SigmaDi Classifier 56 4.3 Estimation Output 57 4.4 Probability Function 58 Chapter 5: Conclusion 59 5.1 Conclusions 59 5.2 Future Research 60 Bibliography 61 Selbstständigkeitserklärung 63
493

Combined Experimental and Mathematical Approach for Development of a Microfabrication-Based Model to Investigate Cell-Cell Interaction during Migration

Sarkar, Saheli 30 March 2011 (has links)
No description available.
494

EVALUATION OF SINGLE MOLECULE DIODES FABRICATED VIA ELECTRON-BEAM LITHOGRAPHY AND METAL-ORGANIC FRAMEWORKS INCORPORATING TWO NOVEL LIGANDS, A TRIGONAL PLANAR CARBOXYLATE LIGAND AND A TETRAHEDRAL TETRAZOLATE-BASED LIGAND

Urig, Christina S. 17 April 2007 (has links)
No description available.
495

Fabrication of a Deoxyribonucleic Acid Polymer Ridge Waveguide Electro-Optic Modulator by Nanoimprint Lithography

Fehrman Cory, Emily Marie 05 June 2014 (has links)
No description available.
496

Heat Transfer from Optically Excited Gold Nanostructures into Water, Sugar, and Salt Solutions

Green, Andrew J. January 2013 (has links)
No description available.
497

Low-Cost Nanopatterning using Self-Assembled Ceramic Nanoislands

Zimmerman, Lawrence Burr 24 September 2009 (has links)
No description available.
498

Nonlinear light propagation and self-inscription processes in a photopolymer doped with Ag nanoparticles

Qiu, Liqun 10 1900 (has links)
<p>The resonance of surface plasmons on metal nanoparticles can be excited at visible wavelengths. The extraordinary enhancement of a variety of optical phenomena in the vicinity of metal nanoparticles has been attributed to the strong fields generated under resonance conditions. As a result, extensive research has been carried out to incorporate the extraordinary optical properties of metal nanoparticles into optical devices and applications, ranging from spectroscopy (e.g, surface enhanced Raman, IR and Fluorescence), optical sensing and imaging, to photovoltaic cells, photonic crystals and optical switches. Particular effort has been directed towards producing stable dispersion of metal nanoparticles within soft dielectric matrices and their subsequent construction into different device geometries.</p> <p>This thesis describes a method to photolytically generate Ag nanoparticles within organosiloxane sols, which can subsequently be photopolymerized in the presence of photoinitiators and therefore, be patterned through a variety of photo-inscription processes. The mechanism of Ag nanoparticle growth and evolution is described in detail followed by the fabrication of periodic metallodielectric gratings through photomask and laser interference lithography. Studies also showed that three different forms of nonlinear light propagation, optical self-trapping, modulation instability and spatial self-phase modulation could be elicited in the Ag nanoparticle-doped systems. Detailed experimental examination of these phenomena elucidated significant differences in their dynamics in the metallodielectric systems compared to non-doped samples. These included variations in the dynamics of self-trapped beams such as the excitation of optical modes, critical thresholds for modulation instability and self-phase modulation. The potential of these nonlinear processes for the self-inscription of 3-D metallodielectric structures including cylindrical multimode waveguides and waveguide lattices has also been studied.</p> / Doctor of Philosophy (PhD)
499

Scalable Electrochemical Surface Enhanced Raman Spectroscopy (EC-SERS) for bio-chemical analysis

Xiao, Chuan 06 October 2021 (has links)
Conducting vertical nanopillar arrays can serve as three-dimensional nanostructured electrodes with improved performance for electrical recording and electrochemical sensing in bio-electronics applications. However, vertical nanopillar-array electrodes made of inorganic conducting materials by conventional nanofabrication approach still faces challenges in high manufacturing costs, poor scalability, and limited choice of carrier substrates. Here, we report a new type of conducting nanopillar arrays composed of multi-walled carbon nanotubes (MWCNTs) doped polymeric nanocomposites, which are manufactured over the wafer-scale on both rigid and flexible substrates by direct nanoimprinting of perfluoropolyether nanowell-array templates into uncured MWCNT/polymer mixtures. By controlling the MWCNT ratios and the annealing temperatures during the fabrication process, MWCNT/polymer nanopillar arrays can possess outstanding electrical properties with high DC conductivity (~4 S/m) and low AC electrochemical impedance (~104 Ω at 1000 Hz). Moreover, by electrochemical impedance spectroscopy (EIS) measurements and equivalent circuit modeling-analysis, we can decompose the overall impedance of MWCNT/polymer nanopillar arrays in the electrolyte into multiple bulk and interfacial circuit components, and thus can illustrate their different dependence on the MWCNT ratios and the annealing temperatures. In particular, we find that a proper annealing process can significantly reduce the anomalous ion diffusion impedance and improve the impedance properties of MWCNT/polymer nanopillars in the electrolyte. / Master of Science / Conducting vertical nanopillar arrays can serve as three-dimensional nanostructured electrodes with improved performance for electrical recording and electrochemical sensing in nano-bioelectronics applications. However, vertical nanopillar-array electrodes made of inorganic conducting materials by conventional nanofabrication approach still faces challenges in high manufacturing costs, poor scalability, and limited choice of carrier substrates. Compared to conventional nanofabrication approaches, nanoimprint lithography exhibits unique advantages for low-cost scalable manufacturing of nanostructures on both rigid and flexible substrates. Very few studies, however, have been conducted to achieve the scalable nanoimprinting fabrication of conducting nanopillar arrays made of MWCNT/polymer nanocomposites. Here, I'm reporting a new type of conducting nanopillar arrays composed of multi-walled carbon nanotubes (MWCNTs) doped polymeric nanocomposites, which can be manufactured over the wafer-scale on both rigid and flexible substrates by direct nanoimprinting of the perfluoropolyether nanowell-array template into uncured MWCNT/polymer mixtures. We find that the nanoimprinted conducting nanopillar arrays can possess appealing electrical properties with a high DC conductivity (~4 S/m) and a low AC electrochemical impedance (~104 Ω at 1000 Hz) in the physiologically relevant electrolyte solutions (1X PBS). Furthermore, I've conducted a systematic equivalent circuit modeling analysis of measured EIS results to understand the effects of the MWCNT ratios and the annealing temperatures on the impedance of different bulk and interfacial circuit components for MWCNT/polymer nanopillar arrays in the electrolyte.
500

Modeling of Diffractive Signatures of Microlithographic Patterns

Mojtahedi, Simon January 2024 (has links)
This thesis explores how the diffraction pattern in the near-field region of a chromium feature edge on a photomask gets altered for three scenarios: First, an analytical study using the Fresnel diffraction integral is performed that investigates what happens when the thin-mask approximation is omitted and the chromium layer is given a thickness. Another analytical study is performed where the edges of a test feature are altered to simulate deviations in the linewidth or a translation of the whole feature, image subtraction is then used to create a difference pattern by subtracting a reference diffraction pattern from the diffraction pattern created by the altered test feature. Lastly, a numerical study using Fourier optics is performed to investigate the effect that introducing four common defects: extrusions, intrusions, dark spots, and pinholes, around the edge will have on the diffraction pattern by subtracting the diffraction pattern from a reference half-plane and again analyzing the resulting difference pattern. Introducing a thickness to the chromium layer alters the diffraction pattern by creating a small crease around the area of the edge in reflective mode, resulting in something similar to a double edge. The high optical density of chromium nullified any effect the thickness had when viewing the system through transmission mode. A linear relation between a change in linewidth or translation of a feature and the peak intensity of the difference pattern is observed that might be used for edge detection. The defect diameter of an extrusion or intrusion seems to correlate in a quadratic way with the peak fringe intensity of the subtracted difference pattern along the x-axis as the defect is fully visible. For a dark spot or pinhole defect being translated away from a chromium edge, the central fringe along the y-axis of the difference pattern follows a sinusoidal curve as it translates further away from the edge. The amplitude of this curve is related to the defect size.

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