Dissertations / Theses: 'Nanoscale materials and structure'

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ADAMO, FABRIZIO CORRADO. "Nanoscale Structure of Advanced Soft Materials for Innovative Applications." Doctoral thesis, Università Politecnica delle Marche, 2020. http://hdl.handle.net/11566/274538.

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Il lavoro di ricerca svolto durante il mio dottorato è stato focalizzato sullo studio di nuovi materiali soffici, in particolare cristalli liquidi, polimeri e sistemi biologici, di particolare interesse per applicazioni innovative nel campo delle nano e bio tecnologie come nuovi dispositivi fotonici ed elettronici, materiali con alte performance meccaniche e biomateriali per la nanomedicina. Lo scopo principale della mia ricerca è stato lo studio delle relazioni tra le peculiari proprietà macroscopiche di questi materiali e la loro struttura nanoscopica. A tal fine, le tecniche di diffrazione e scattering di raggi X hanno avuto un ruolo chiave, in quanto sono state usate come principale strumento di studio. Gli esperimenti sono stati condotti presso sorgenti di luce di sincrotrone quali l’European Synchrotron Radiation Facility, Grenoble (Francia), ELETTRA, Trieste (Italia) e ALBA, Barcellona (Spagna), nel contesto di esperimenti approvati ufficialmente. Inoltre, in collaborazione con altri gruppi di ricerca internazionale, sono state applicate tecniche complementari a questi materiali per ottenere una caratterizzazione completa. Il lavoro di ricerca può essere identificato in quattro tematiche principali: i) l’influenza della struttura molecolare sulla fase nematica di cristalli liquidi bent-core. La recente scoperta della nanostruttura cibotattica della loro fase nematica rende queste molecole i candidati ideali per le due proprietà più ricercate ed elusive dei cristalli liquidi, cioè la biassialità e la ferroelettricità nella fase nematica, largamente riconosciute come le pietre miliari della scienza dei cristalli liquidi. I risultati ottenuti suggeriscono utili indizi per guidare la ricerca verso la sintesi di mesogeni bent-core che mostrano tali caratteristiche; ii) lo studio delle nanostrutture e dell’ordine molecolare di film ultra sottili di mesogeni bent-core depositati su substrati solidi per conoscere i meccanismi di ancoraggio e self-assembling di molecole di cristallo liquido all’interfaccia, studiando l’arrangiamento spaziale delle molecole (ordine in-plane e out-of-plane). Abbiamo ottenuto un film altamente ordinato con una struttura anisotropa in-plane delle molecole di cristallo liquido, risultato mai riportato in letteratura per questi sistemi; iii) studio strutturale di un cristallo liquido termotropico reattivo usato nella produzione di una nuova classe di thermoset (networks 3D interconnessi designati a preservare la morfologia nematica locale nello stato solido) con alte performance. Esperimenti di diffrazione di raggi X alle alte temperature hanno reso possibile per la prima volta il monitoraggio della trasformazione del gruppo etinilico terminale e seguire l’evoluzione della fase nematica durante il cross-linking della catena; iv) la caratterizzazione strutturale e fisico-chimico di innovativi nanosistemi liquido cristallini per la loro potenziale applicazione nello sviluppo di vettori efficienti e biocompatibili per il drug delivery nel campo della nanomedicina. Lo studio è stato focalizzato sull’incorporazione di un surfattante cationico nella fase cubica del fitantriolo, con e senza il farmaco antitumorale fluorouracile. Lo studio ha evidenziato l’efficienza del sistema fitantriolo/surfattante ionico come vettore per il drug delivery antitumorale.
My Ph.D. research work was focused on the investigation of new soft materials, in particular new liquid crystals, polymers and biosystems, of potential interest for innovative applications in the fields of nano- and bio-technologies including novel electronic and photonic devices, high mechanical-performance materials, biomaterials for nanomedicine and biosensing. The main purpose of my research work was the study of the relationships between the peculiar macroscopic properties of these materials and their structure at the nanoscale. To this end, a key role was played by the X-ray diffraction and scattering techniques used as the primary tool of experimental investigation. The X-ray measurements were carried out at the synchrotron light sources of the European Synchrotron Radiation Facility, Grenoble (France), ELETTRA, Trieste (Italy), and ALBA, Barcelona (Spain), in the context of officially approved experiments. A series of complementary techniques were also employed to better characterize these materials, in collaboration with other international research groups. The research work can be identified with four main topics: i) the influence of the molecular structure on the nematic phase of bent-core liquid crystals. The recently discovered cybotactic nanostructure of their nematic phase makes them the ideal candidates for the two most sought after and elusive properties of liquid crystals, namely the nematic biaxiality and the nematic ferroelectricity, widely recognized as the Holy Grail of the liquid crystal science. The findings suggest useful clues to guide the research effort towards the synthesis of novel bent-core mesogens exhibiting such features; ii) the study of the nanostructure and molecular ordering of ultra-thin films of bent-core mesogens deposited on solid substrate to gain insight into the mechanisms of anchoring and self-assembling of liquid crystal molecules at the interface and investigate the molecular space arrangement (in-plane and out-of-plane order). We obtained a highly ordered film with the anisotropic in-plane structure of the liquid crystal molecules, which has never been reported in the literature for these systems; iii) structural study of a reactive thermotropic liquid crystal used in the production of a new class of high-temperature/high-performance thermosets - crosslinked 3D networks designed to preserve the local nematic morphology in the solid state. High-temperature X-ray diffraction studies made it possible for the first time to monitor the transformation of the ethynyl end-group and to follow the evolution of the nematic phase during the chain extension/cross-linking reactions; iv) the structural and physico-chemical characterization of novel lyotropic liquid crystalline nanosystems for their potential applications in the development of efficient and biocompatible vectors for drug delivery in nanomedicine. The study was focused on the incorporation of a cationic surfactant in the phytantriol cubic phase, unloaded and loaded with the anticancer drug 5-fluorouracil. The study evidences the efficiency of the phytantriol/ionic surfactant system as anticancer drug delivery vectors.

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Kuna, Jeffrey James. "The effect of nanoscale structure on interfacial energy." Thesis, Massachusetts Institute of Technology, 2011. http://hdl.handle.net/1721.1/62744.

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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 2011.
Vita. Cataloged from PDF version of thesis.
Includes bibliographical references.
Interfaces are ubiquitous in nature. From solidification fronts to the surfaces of biological cells, interfacial properties determine the interactions between a solid and a liquid. Interfaces, specifically liquid-solid interfaces, play important roles in many fields of science. In the field of biology, interfaces are fundamental in determining cell-cell interactions, protein folding behavior and assembly, and ligand binding. In chemistry, heterogeneous catalysts greatly increase reaction rates of reactions occurring at the interface. In materials science, crystallization and the resulting crystal habit are determined by interfacial properties, and interfaces affect diffusion through polycrystalline materials. In nanotechnology, much work on self-assembly, molecular recognition, catalysis, electrochemistry and numerous other applications depends on the properties of interfaces. The structure and properties of interfaces have been studied experimentally using a variety of techniques including various forms of microscopy, wetting measurements, and scattering techniques. Conventionally, the typical interface considered was highly homogeneous and exhibited a uniform composition and roughness. In contrast, many of the interfaces encountered in biological or nanotechnological systems have surfaces with a greater degree of complexity. While the surface may be compositionally homogeneous over a large area, these surfaces are structured and have a complex surface topology. On a mixed interface, several different chemical groups may be present on the surface, and the chemical composition can vary on a sub-nanometer length scale. Structured systems are inherently difficult to experimentally measure. Most techniques available to characterize interfaces average properties over the entire surface and are not sensitive to nanoscale variations. Furthermore, many of these techniques are incapable of distinguishing global, surface-dependent properties from artifactual influences. Many surface characterization techniques require a large, flat, smooth surface. Preparation of mixed interfaces is an experimental challenge as well as many mixed interfaces with nanoscale structure are present on objects that are themselves nanoscale, such as proteins. Several technological hurdles exist that limit the ability to produce nanoscale mixed interfaces large enough for conventional measurements. In this thesis, the effect of surface structure on wetting behavior was investigated. Interfaces can be characterized by the energy required to form them, a quantity called interfacial energy. Models have been developed to describe the interfacial energy of mixed interfaces for a wide range of surfaces. These models only account for the composition of the surface. The wetting behavior of mixed surfaces has also been related to artifact-dependent wetting effects (namely the effect of a boundary or asperity). No attempt has been made to incorporate surface structure into a global expression of interfacial energy. This thesis will study how the structure of an interface determines the resulting interfacial energy. Surfaces prepared with chemical domains of different length scales demonstrate and interfacial energy trend with significant deviation from the current best model. Specifically, the observed trend is non-linear, unlike the conventional model, and furthermore in some cases, is non-monotonic. These deviations are shown to stem from the surfaces' intrinsic structure and are not an artifact of the measurement process or surface defects. The deviations from the predicted trend are explained by the molecular scale structure of the solvent. The two proposed mechanisms, cavitation and confinement, arise when surface features are smaller than a solvent-dependent length. With cavitation, nonwetting surface features below a size threshold are more wetting than would be expected. With confinement, wetting patches become less wetting as their dimensions are decreased. Molecular dynamics simulations support the proposed mechanisms. Additional experimental results provide further experimental evidence of the proposed molecular-scale wetting phenomena.
by Jeffrey James Kuna.
Ph.D.

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Ma, Fengxian. "Computational exploration of structure and electronic functionality in nanoscale materials." Thesis, Queensland University of Technology, 2017. https://eprints.qut.edu.au/112361/1/Fengxian_Ma_Thesis.pdf.

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This project is a systematic study regarding the discovery and design of nanomaterials with potential applications in electronic devices. It reveals several promising candidates such as a new phase of transition metal dichalcogenides and the two-dimensional ionic boron sheet with novel electronic properties, which enrich the family of two-dimensional materials. The comprehensive calculations would also be a good guidance for the experimental realisation in the near future.

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Janko, Marek. "Structure and stability of biological materials – characterisation at the nanoscale." Diss., lmu, 2012. http://nbn-resolving.de/urn:nbn:de:bvb:19-143453.

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Tuchband, Michael R. "Revealing the Nanoscale Structure and Behavior of the Twist-Bend Nematic Liquid Crystal Phase." Thesis, University of Colorado at Boulder, 2018. http://pqdtopen.proquest.com/#viewpdf?dispub=10752109.

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The nematic phases of liquid crystals have been the most thoroughly investigated since the founding of the liquid crystal field in the early 1900’s. The resulting technologies, most notably the liquid crystal display, have changed our world and spawned an entire industry. Consequently, the recent identification of a new type of nematic – the twist-bend nematic – was met with as much surprise as excitement, as it melds the fluid properties and environmental responsiveness of conventional nematics with the intrinsic polarization and complex ordering of bent-core liquid crystals. I summarize the history of the twist-bend nematic phase, charting the development of our understanding from its first identification to the present day. Furthermore, I enumerate and highlight my own efforts in the field to characterize the behavior and nanoscale organization of the twist-bend phase.

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Ehrlich, Deborah J. C. "Synthetic strategies for control of structure from individual macromolecules to nanoscale materials to networks." Thesis, Massachusetts Institute of Technology, 2019. https://hdl.handle.net/1721.1/122451.

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Thesis: Ph. D., Massachusetts Institute of Technology, Department of Chemistry, 2019
Cataloged from PDF version of thesis.
Includes bibliographical references.
Chapter 1. Aqueous self-assembly of prodrug macromonomers. A series of highly tunable micelles for drug delivery were made from norbornene based poly(ethylene glycol) macromonomers with covalently linked drugs. A total of five macromonomers were made using three different drugs (telmisartan, paclitaxel, and SN-38) and three different drug loadings. Combinations of these macromonomers were then allowed to self assemble into micellar aggregates. The size, stability, and shape of these micellar aggregates were controlled with the highly versatile structure. Chapter 2. Post micellization modification of norbornene-containing prodrug macromonomers. Highly tunable micelles for drug delivery were functionalized after their selfassembly. Post-micellization inverse electron demand Diels-Alder reactions of norbornenes and tetrazines were used to signal changes in micelle size and stability through the addition of either hydrophilic or hydrophobic tetrazines.
Thiol-ene additions reactions were used to increase micelle size and form chemically crosslinked nanoparticles. These modifications of norbornene-containing prodrug macromonomer assemblies illustrate their versatility. Chapter 3. Synthesis of polymers by iterative exponential growth. A scalable synthetic route that enables absolute control over polymer sequence and structure has remained a key challenge in polymer chemistry. Here, we report an iterative exponential growth plus side-chain functionalization (IEG+) strategy for the production of macromolecules with defined sequence, length, and stereoconfiguration. Each IEG+ cycle begins with the azide opening of an enantiopure epoxide, followed by side chain functionalization, alkyne deprotection, and copper-catalyzed azide-alkyne cycloaddition (CuAAC). These cycles have been conducted to form unimolecular macromolecules with molar masses of over 6,000 g/mol.
Subsequent modifications to IEG+ allow for the functionalization of monomers prior to the IEG+ cycle, expanding the library of compatible side chain chemistries. Chapter 4. Introduction to elastomer toughening strategies. Silicone elastomers are ubiquitous. Here, silicone elastomers are discussed in terms of network structure, the impact of network structure upon physical properties, and modifications of network structure in order to achieve desired physical properties. Fillers, the standard toughening strategy, are discussed in conjunction with entanglement density. Focus is placed on the impact of entanglement density on material properties. Topological networks are discussed and noted for their stress dissipative properties. Chapter 5. Topology modification of polydimethylsiloxane elastomers through loop formation. Topological networks are well known for their stress dissipation through the pulley effect leading to soft, extensible materials.
Combining these properties with a traditionally crosslinked network to produce a hybrid material allows for enhanced extensibility without a loss in modulus. Here, such hybrid networks were made with poly(dimethyl siloxane) polymers of a range of molecular weights. Side-loop polymer brushes were synthesized and then crosslinked to create hybrid networks with the statistical formation of topological bonds. These materials were characterized through tensile testing. Elastomers formed with the same molecular weight polymer in both side-loops and network formation did not show mechanical properties that depended upon the fraction of networks used for brush formation. Elastomers made with long polymers in brush formation and shorter polymers for network formation resulted in highly extensible systems without significant loss in modulus.
by Deborah J.C. Ehrlich.
Ph. D.
Ph.D. Massachusetts Institute of Technology, Department of Chemistry

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Salahshoor, Pirsoltan Hossein. "Nanoscale structure and mechanical properties of a Soft Material." Digital WPI, 2013. https://digitalcommons.wpi.edu/etd-theses/924.

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"Recently, hydrogel have found to be promising biomaterials since their porous structure and hydrophilicity enables them to absorb a large amount of water. In this study the role of water on the mechanical properties of hydrogel are studied using ab-initio molecular dynamics (MD) and coarse-grained simulations. Condensed-Phased Optimized Molecular Potential (COMPASS) and MARTINI force fields are used in the all-atom atomistic models and coarse-grained simulations, respectively. The crosslinking process is modeled using a novel approach by cyclic NPT and NVT simulations starting from a high temperature, cooling down to a lower temperature to model the curing process. Radial distribution functions for different water contents (20%, 40%, 60% and 80%) have shown the crosslinks atoms are more hydrophilic than the other atoms. Diffusion coefficients are quantified in different water contents and the effect of crosslinking density on the water diffusion is studied. Elasticity parameters are computed by constant strain energy minimization in mechanical deformation simulations. It is shown that an increase in the water content results in a decrease in the elastic. Finally, continuum hyper elastic model of contact lens is studied for three different loading scenarios using Finite Element Model. "

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Janko, Marek [Verfasser], and Robert [Akademischer Betreuer] Stark. "Structure and stability of biological materials – characterisation at the nanoscale / Marek Janko. Betreuer: Robert Stark." München : Universitätsbibliothek der Ludwig-Maximilians-Universität, 2012. http://d-nb.info/1022791176/34.

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Hatton, Hilary J. "Magnetic and structural studies of nanoscale multilayer and granular alloy systems of Ag and FeCo." Thesis, University of Sheffield, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.286916.

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Schiffrin, Agustin. "Self-assembly of amino acids on noble metal surfaces : morphological, chemical and electronic control of matter at the nanoscale." Thesis, University of British Columbia, 2008. http://hdl.handle.net/2429/798.

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Designing novel nanostructures which exploit the self-assembly capabilities of biomolecules yields a promising approach to control matter at the nanoscale. Here, the homochiral molecular self-assemblies of the methionine and tyrosine amino acids on the monocrystalline Ag(111) and Cu(111) surfaces are characterized by means of scanning tunneling microscopy (STM) and spectroscopy (STS), helium atom scattering (HAS), x-ray photoelectron spectroscopy (XPS) and near-edge x-ray absorption fine structure (NEXAFS) in ultrahigh vacuum (UHV). On Ag(111), methionine self-assembles into supramolecular chains following the <110> substrate axis, forming regular nanogratings with tunable periodicity. Within the nanowires, a zwitterionic dimerization scheme is revealed. STS shows that the biomolecular nanostructures act as tunable one-dimensional quantum resonators for the surface state electrons. Zero-dimensional electronic confinement is achieved by positioning single iron atoms in the molecular trenches. This shows a novel approach to control the dimensionality of surface state electrons. The nanogratings were exploited to steer the spontaneous one-dimensional ordering of cobalt and iron atoms. For T > 15 K, the metal species self-align into homogeneously distributed chains in between the biomolecular trenches with ~25 Å interatomic distace. For Co, the dynamics of the self-alignment was monitored, revealing a reduced mobility in comparison with isolated Co atoms on bare Ag(111). On Cu(111), the self-assembly of methionine is influenced by the substrate reactivity and its temperature during molecular deposition. For T < 273 K, the biomolecules assemble in anisotropic extended clusters oriented with a -10° rotation off the <110> substrate orientations, whereas above 283 K a regularly ordered 1D phase arises with a +10° rotation off these high-symmetry axis. XPS reveals a structural transformation triggered by a thermally activated deprotonation of the zwitterionic ammonium group. On Ag(111), tyrosine self-assembles above a critical temperature into linear structures primarily following the substrate crystalline symmetry. A zwitterionic non-covalent molecular dimerization is demonstrated, NEXAFS data providing evidence of a non-flat adsorption of the phenyl ring. This recalls the geometrical pattern of methionine on Ag(111) and supports a universal self-assembling scheme for amino acids on close-packed noble metal surfaces, the different mesoscopic ordering being determined by the side chain reactivity.

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Зленко, Віталій Олександрович, Виталий Александрович Зленко, Vitalii Oleksandrovych Zlenko, Михайло Валерійович Каверін, Михаил Валерьевич Каверин, and Mykhailo Valeriiovych Kaverin. "Апаратно-програмний комплекс дослідження терморезистивних властивостей тонких плівок." Thesis, Вид-во СумДУ, 2009. http://essuir.sumdu.edu.ua/handle/123456789/3986.

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Науковий керівник - Проценко Сергій Іванович
Метою нашої роботи було створення автоматизованої системи управління науковим експериментом для дослідження терморизестивних властивостей плівкових матеріалів. При цитуванні документа, використовуйте посилання http://essuir.sumdu.edu.ua/handle/123456789/3986

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Ohmura, Jacqueline (Jacqueline Frances). "Utilizing viruses to probe the material process - structure - property relationship : controlling catalytic properties via protein engineering and nanoscale synthesis." Thesis, Massachusetts Institute of Technology, 2018. http://hdl.handle.net/1721.1/115761.

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Thesis: Ph. D., Massachusetts Institute of Technology, Department of Biological Engineering, 2018.
Cataloged from PDF version of thesis.
Includes bibliographical references (pages 136-146).
From the fabrication of fine chemicals, to the increasing attainability of a non-petrochemical based energy infrastructure, catalysts play an important role in meeting the increasing energy and consumable demands of today without compromising the global health of tomorrow. Development of these catalysts relies on the fundamental understanding of the effects individual catalyst properties have on catalytic function. Unfortunately, control, and therefore deconvolution of individual parameter effects, can be quite challenging. Due to the nanoscale formfactor and wide range of available surface chemistries, biological catalyst fabrication affords one solution to this challenge. To this end, this work details the processing of M13 bacteriophage as a synthetic toolbox to modulate key catalyst parameters to elucidate the relationship between catalyst structure and performance. With respect to electrocatalysis, a biotemplating method for the development of tunable 3D nanofoams is detailed. Viral templates were rationally assembled into a variety of genetically programmable architectures and subsequently templated into a variety of material compositions. Subsequently, this synthetic method was employed to examine the effects of nanostructure on electro-catalytic activity. Next, nanoparticle driven heterogeneous catalysis was targeted. Nanoparticle-protein binding affinities were leveraged to explore the relationship between nanoparticles and their supports to identify a selective, base free alcohol oxidation catalyst. Finally, the surface proteins of the M13 virus were modified to mirror homogeneous copper-ligand chemistries. These viruses displayed binding pocket free copper complexation and catalytic efficacy in addition to recyclability and solvent robustness. Subsequently, the multiple functional handles of the viron were utilized to create catalytic ensembles of varying ratios. Single and dendrimeric TEMPO (4-Carboxy-2,2,6,6-tetramethylpiperidine 1-oxyl) were chemically conjugated to the surface of several catalytically active phage clones further tailoring catalytic function. Taken together, these studies provide strong evidence of the utility of biologically fabricated materials for catalytic design.
by Jacqueline Ohmura.
Ph. D.

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Leininger, Wyatt Christopher. "Design and Control of a Micro/Nano Load Stage for In-Situ AFM Observation and Nanoscale Structural and Mechanical Characterization of MWCNT-Epoxy Composites." Thesis, North Dakota State University, 2018. http://pqdtopen.proquest.com/#viewpdf?dispub=10680380.

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Nanomaterial composites hold improvement potential for many materials. Improvements arise through known material behaviors and unique nanoscale effects to improve performance in areas including elastic modulus and damping as well as various processes, and products. Review of research spurred development of a load-stage. The load stage could be used independently, or in conjunction with an AFM to investigate bulk and nanoscale material mechanics.

The effect of MWCNT content on structural damping, elastic modulus, toughness, loss modulus, and glass transition temperature was investigated using the load stage, AMF, and DMA. Initial investigation showed elastic modulus increased 23% with 1wt.% MWCNT versus pure epoxy and in-situ imaging observed micro/nanoscale deformation.

Dynamic capabilities of the load stage were investigated as a method to achieve higher stress than available through DMA. The system showed energy dissipation across all reinforce levels, with ~480% peak for the 1wt.% MWCNT material vs. the neat epoxy at 1Hz.

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Leininger, Wyatt C. "Design and Control of a Micro/Nano Load Stage for In-Situ AFM Observation and Nanoscale Structural and Mechanical Characterization of MWCNT-Epoxy Composites." Thesis, North Dakota State University, 2017. https://hdl.handle.net/10365/28190.

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Nanomaterial composites hold improvement potential for many materials. Improvements arise through known material behaviors and unique nanoscale effects to improve performance in areas including elastic modulus and damping as well as various processes, and products. Review of research spurred development of a load-stage. The load stage could be used independently, or in conjunction with an AFM to investigate bulk and nanoscale material mechanics. The effect of MWCNT content on structural damping, elastic modulus, toughness, loss modulus, and glass transition temperature was investigated using the load stage, AMF, and DMA. Initial investigation showed elastic modulus increased 23% with 1wt.% MWCNT versus pure epoxy and in-situ imaging observed micro/nanoscale deformation. Dynamic capabilities of the load stage were investigated as a method to achieve higher stress than available through DMA. The system showed energy dissipation across all reinforce levels, with ~480% peak for the 1wt.% MWCNT material vs. the neat epoxy at 1Hz.
ND NASA EPSCoR FAR0017788
NDSU Development Foundation FAR0017503
National Science Foundation (NSF) Grant# HRD-0811239 to the NDSU Advance FORWARD Program

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Gao, Hantian. "Nanoscale Characterization and Control of Native Point Defects in Metal Oxide Semiconductors and Device Structures." The Ohio State University, 2021. http://rave.ohiolink.edu/etdc/view?acc_num=osu1618838504594148.

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Casalena, Lee. "Multimodal Nanoscale Characterization of Transformation and Deformation Mechanisms in Several Nickel Titanium Based Shape Memory Alloys." The Ohio State University, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=osu1499568013015563.

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Almahmoud, Khaled Hasan Musa. "Thermal Transport Modeling in Three-Dimensional Pillared Graphene Structures for Efficient Heat Removal." Thesis, University of North Texas, 2020. https://digital.library.unt.edu/ark:/67531/metadc1752407/.

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Pillared-graphene structure (PGS) is a novel three-dimensional structure consists of parallel graphene sheets that are separated by carbon nanotube (CNT) pillars that is proposed for efficient thermal management of electronics. For microscale simulations, finite element analyses were carried out by imposing a heat flux on several PGS configurations using a Gaussian pulse. The temperature gradient and distribution in the structures was evaluated to determine the optimum design for heat transfer. The microscale simulations also included conducting a mesh-independent study to determine the optimal mesh element size and shape. For nanoscale simulations, Scienomics MAPS software (Materials And Processes Simulator) along with LAMMPS (Large-scale Atomic/ Molecular Massively Parallel Simulator) were used to calculate the thermal conductivity of different configurations and sizes of PGS. The first part of this research included investigating PGS when purely made of carbon atoms using non-equilibrium molecular dynamics (NEMD). The second part included investigating the structure when supported by a copper foil (or substrate); mimicking production of PGS on copper. The micro- and nano-scale simulations show that PGS has a great potential to manage heat in micro and nanoelectronics. The fact that PGS is highly tunable makes it a great candidate for thermal management applications. The simulations were successfully conducted and the thermal behavior of PGS at the nanoscale was characterized while accounting for phonon scattering the graphene/CNT junction as well as when PGS is supported by a copper substrate.

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Nilwala, Gamaralalage Premasiri Kasun Viraj Madusanka. "Electron Transport in Chalcogenide Nanostructures." Case Western Reserve University School of Graduate Studies / OhioLINK, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=case1572259784431038.

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Choi, Fung Sing. "Nanoscale electrical characterisation of nitride structures." Thesis, University of Cambridge, 2018. https://www.repository.cam.ac.uk/handle/1810/283496.

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To fully exploit the potential of gallium nitride (GaN) devices for optoelectronics and power electronic applications, the structures of device need to be investigated and optimized. In particular carrier densities, conductivities and localised charges can have a significant impact to device performances. Electrical scanning probe microscopy techniques, including scanning capacitance microscopy (SCM), conductive atomic force microscopy (C-AFM) and kelvin probe force microscopy (KPFM), were utilized to study the structures of nitride devices such as high electron mobility transistors (HEMTs), light emitting diodes (LEDs) and junction diodes. These results combine with other characterisation techniques to give an enhanced understanding about the nitride structures. Leakage currents are one of the major challenges in HEMTs, especially leakages in buffer layers which deteriorate the breakdown voltage of the devices. To achieve an insulating buffer layer, carbon doping is usually used to compensate the unintentional n-type doping of nitride materials. Here, I show that vertical leakage can originate from the formation of inverted hexagonal pyramidal defects during the low temperature growth of an AlGaN:C strain relief layer. The semi-polar facets of the defects enhanced the oxygen incorporation and led to the formation of leakage pathways which were observed using SCM. Leakage occurring at HEMT surfaces will lead to current collapses of devices. In this work, I discovered nano-cracks on a HEMT surface. C-AFM showed enhanced conductivity along these nano-cracks. A model based on stress relaxation analysis was proposed to explain the drop of surface potential along the nano-cracks. Advances in the quality of epitaxial GaN grown by MOVPE have been facilitated by understanding the formation of defects within the materials and structures. However, hillocks as a specific type of defects have not been intensively studied yet. In this work, three types of hillocks were discovered on GaN p-i-n diodes and a GaN film grown on patterned sapphire substrates. It was found that pits were always present around the centres of hillocks. Multi-microscopy results showed these pits were developed from either an inversion domain or a nano-pipe or a void under the sample surface. Formation of hillocks was usually associated with a change of growth condition, such as an increase in Mg doping or a decrease in growth temperature and gas flows, despite the formation mechanism is still unclear. GaN$_{1-x}$As$_x$ is a highly mismatched alloy semiconductor whose band-gap can be engineered across the whole visible spectrum. For this reason and the potential to achieve high p-type doping, GaN$_{1-x}$As$_x$ is a promising material for optoelectronic applications. However, the growth of GaN$_{1-x}$As$_{x}$ at intermediate As fraction while maintaining a high conductivity and uniformity of the material is still challenging. Two n-GaN/p-GaN$_{1-x}$As$_x$ diodes with different Ga flows were investigated. Both samples demonstrated that highly Mg-doped GaN$_{1-x}$As$_x$ with high As fraction is achievable. However, the samples contained both amorphous and polycrystalline regions. The electrical scanning probe microscopy results suggested the amorphous structure has a lower hole concentration and hence conductivity than the polycrystalline structure. Nevertheless, there is still a lack of understanding about the electrical properties and conduction mechanisms of the GaN$_{1-x}$As$_x$ alloy.

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Aili, Daniel. "Polypeptide-Based Nanoscale Materials." Doctoral thesis, Linköpings universitet, Sensorvetenskap och Molekylfysik, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-15124.

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Self-assembly has emerged as a promising technique for fabrication of novel hybrid materials and nanostructures. The work presented in this thesis has been focused on developing nanoscale materials based on synthetic de novo designed polypeptides. The polypeptides have been utilized for the assembly of gold nanoparticles, fibrous nanostructures, and for sensing applications. The 42-residue polypeptides are designed to fold into helix-loop-helix motifs and dimerize to form four-helix bundles. Folding is primarily driven by the formation of a hydrophobic core made up by the hydrophobic faces of the amphiphilic helices. The peptides have either a negative or positive net charge at neutral pH, depending on the relative abundance of Glu and Lys. Charge repulsion thus prevents homodimerization at pH 7 while promoting hetero-dimerization through the formation of stabilising salt bridges. A Cys incorporated in position 22, located in the loop region, allowed for directed, thiol-dependent, immobilization on planar gold surfaces and gold nanoparticles. The negatively charged (Glu-rich) peptide formed homodimers and folded in solution at pH < 6 or in the presence of certain metal ions, such as Zn2+. The folding properties of this peptide were retained when immobilized directly on gold, which enabled reversible assembly of gold nanoparticles resulting in aggregates with well-defined interparticle separations. Particle aggregation was found to induce folding of the immobilized peptides but folding could also be utilized to induce aggregation of the particles by exploiting the highly specific interactions involved in both homodimerization and hetero-association. The possibility to control the assembly of polypeptide-functionalized gold nanoparticles was utilized in a colorimetric protein assay. Analyte binding to immobilized ligands prevented the formation of dense particle aggregates when subjecting the particles to conditions normally causing extensive aggregation. Analyte binding could hence easily be distinguished by the naked eye. Moreover, the peptides were utilized to assemble gold nanoparticles on planar gold and silica substrates. Fibrous nanostructures were realized by linking monomers through a disulphide-bridge. The disulphide-linked peptides were found to spontaneously assemble into long and extremely thin peptide fibres as a result of a propagating association mediated by folding into four-helix bundles.
Ingenjörer och vetenskapsmän har ofta inspirerats av naturen i sökandet efter lösningar på tekniska problem. Allt ifrån byggnadskonstruktioner, flygplansvingar, kompositmaterial till kardborrebandet har skapats med utgångspunkt från förebilder i naturen. Många av de material och konstruktioner som återfinns i naturen har åtråvärda egenskaper som är svåra att erhålla i syntetiska matrial med traditionell teknik. Även om vi i flera fall kan härma sammansättningen och formen blir resultatet inte nödvändigtvis det samma. Den största skillnaden mellan syntetiska material och material producerade av levande organismer är hur deras komponenter sinsemellan är organiserade och sammansatta. I syntetiska material är komponenterna ofta inbördes mer eller mindre slumpvis ordnade medan de i biologiska material är organiserade med en oerhörd precision som sträcker sig ända ned på molekyl- och atomnivå. Naturens byggstenar har genom evolutionens gång förfinats för att spontant kunna organisera sig och bilda komplexa material och strukturer. Denna process, som styrs genom att många svaga krafter inom och mellan byggstenarna samverkar, kallas ofta för självorganisering och är en förutsättning för allt liv. Självorganisering har också blivit en allt viktigare metod inom nanotekniken för att konstruera material och strukturer med nanometerprecision. I den här avhandlingen beskrivs en typ av självorganiserande material där byggstenarna utgörs av nanometerstora guldpartiklar och syntetiska proteiner. De syntetiska proteinerna är designade för att efterlikna naturliga biomolekyler och antar en välbestämd tredimensionell struktur när två av dem interagerar med varandra. Denna interaktion är mycket specifik men kan styras genom att variera kemiska parametrar som surhet och jonstyrka vilket ger en möjlighet att påverka och kontrollera proteinernas struktur. Proteinerna har vidare modifierats för att spontant organisera sig till fibrer som är flera mikrometer långa men endast några nanometer tjocka. Proteinfibrer utgör en mycket viktig typ av strukturer i biologiska system och finns i alltifrån spindelväv till muskler. Syntetiska proteinfibrer är därför både ett intressant modellsystem och ett material med många potentiellt intressanta användningsområden. Genom att fästa de syntetiska proteinerna på ytan av guldnanopartiklar går interaktionerna mellan partiklarna att kontrollera på samma sätt som interaktionerna mellan proteinerna. Krafterna mellan proteinerna och interaktionerna involverade i proteinernas veckning har använts för att reversibelt aggregera och organisera nanopartiklarna. Ett antal olika byggstenar har studerats och utvecklats till något som liknar ett mycket enkelt nano-Lego, som på en given signal spontant bygger ihop sig eller trillar isär. Guldnanopartiklar är intressanta eftersom de är stabila och lätta att modifiera kemiskt men också på grund av deras optiska egenskaper som ger dem en ovanligt vacker vinröd färg. Färgen uppstår på grund av partiklarnas ringa storlek och varierar naturligt med egenskaperna hos den omgivande miljön. Detta gör det enkelt att studera hur partiklarna interagerar eftersom de byter färg när de närmar sig varandra, men gör dem också intressanta för sensortillämpningar. En enkel och robust sensor beskrivs i avhandlingen där syntetiska proteiner, speciellt utformade för att upptäcka och binda andra molekyler, har fästs på nanopartiklarna. Med partiklarnas hjälp går det att med blotta ögat detektera ett mänskligt protein i koncentrationer under ett tusendels gram per liter. En tidig diagnos av sjukdomstillstånd kan i de flesta fall avsevärt underlätta behandlingen och behovet av enkla sensorer för att bestämma närvaro och koncentration av medicinskt intressanta molekyler är därför mycket stort.

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21

Duzhko, Volodimyr. "Photovoltage phenomena in nanoscale materials." [S.l.] : [s.n.], 2002. http://deposit.ddb.de/cgi-bin/dokserv?idn=964920964.

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22

Sattar, Abdul. "Electrical Characterization of Cluster Devices." Thesis, University of Canterbury. Physics and Astronomy, 2011. http://hdl.handle.net/10092/6677.

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The aim of the study presented in this thesis is to explore the electrical and physical properties of films of tin and lead clusters. Understanding the novel conductance properties of cluster films and related phenomenon such as coalescence is important to fabricate any cluster based devices. Coalescence is an important phenomenon in metallic cluster films. Due to coalescence the morphology of the films changes with time which changes their properties and could lead to failure in cluster devices. Coalescence is studied in Sn and Pb cluster films deposited on Si$_3$N$_4$ surfaces using Ultra High Vacuum (UHV) cluster deposition system. The conductance of the overall film is linked to the conductance of the individual necks between clusters by simulations. It is observed that the coalescence process in Sn and Pb films follows a power law in time with an exponent smaller than reported in literature. These results are substantiated by the results from previous experimental and Kinetic Monte Carlo (KMC) simulation studies at UC. Percolating films of Sn show unique conductance properties. These films are characterized using various electrode configurations, applied voltages and temperatures. The conductance measurements are performed by depositing clusters on prefabricated gold electrodes on top of Si$_3$N$_4$ substrates. Sn cluster films exhibit a variety of conductance behaviours during and after the end of deposition. It is observed that the evolution of conductance during the onsets at percolation threshold is dependent on the film morphology. Samples showing difference responses in onset also behave differently after the end of deposition. Therefore all samples were categorized according to their onset behaviour. After the end of deposition, when a bias voltage is applied, the conductance of Sn films steps up and down between various well-defined conductance levels. It is also observed that in many cases the conductance levels between which these devices jump are close to integral multiples of the conductance quantum. There are many possible explanations for the steps in conductance. One of the explanations is formation and breaking of conducting paths in the cluster films by electric field induced evaporation and electromigration respectively. The stepping behaviour is similar to that in non-volatile memory devices and hence very interesting to explore due to potential applications.

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Kim, Sung-gi. "PET Nanocomposites Development with Nanoscale Materials." Connect to Online Resource-OhioLINK, 2007. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1178043237.

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Dissertation (Ph.D.)--University of Toledo, 2007.
Typescript. "Submitted as partial fulfillment of the requirements for The Doctor of Philosophy Degree in Engineering." Bibliography: leaves 200-205.

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Wang, Jinfeng. "Characterization and synthesis of nanoscale materials." Diss., Rolla, Mo. : Missouri University of Science and Technology, 2008. http://scholarsmine.mst.edu/thesis/pdf/JinfengWang_09007dcc80564540.pdf.

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Thesis (Ph. D.)--Missouri University of Science and Technology and University of Missouri--St. Louis, 2008.
Vita. The entire thesis text is included in file. Title from title screen of thesis/dissertation PDF file (viewed August 28, 2008) Thesis completed as part of a cooperative degree program with Missouri University of Science & Technology and the University of Missouri--St. Louis. Includes bibliographical references (p. 129-142).

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25

Raanaei, Hossein. "Tailoring Properties of Materials at the Nanoscale." Doctoral thesis, Uppsala : Uppsala University, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-107425.

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26

Wang, Wentai. "Synthesis and Applications of Nanoscale Carbon Materials." Thesis, Griffith University, 2015. http://hdl.handle.net/10072/366678.

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Carbon nanomaterials are gaining more attention due to some special features, such as the excellent photoluminescent (PL) properties, low toxicity and biocompability of carbon dots (CDs) and good conductivity, high mechanical strength and stability of graphene based nanomaterials or membranes, inspiring emerging area for applications. Considering the drawbacks including limitations in large-scale synthesis, cost, low yields and pollutions, efforts should be devoted to improve the synthetic technique to achieve green, economic and mass synthesis, and explore novel applications. In this thesis, different types of CDs were prepared through hydrothermal/solvothermal method, modifying the surface of CDs to improve the chemical and optical properties. In addition, the performance of graphene based nanomaterials and membranes in water purification are investigated as well. Two types of CDs are synthesized in this thesis, including organosilane functionalized CDs (OS-CDs) and nitrogen-doped CDs (NCDs). The products show high quantum yields (QY) and good stability after hydrothermal treatment, with QY as high as 51 % for OS-CDs and around 20% for the NCDs. These CDs show sensitivity to some parameters such as temperature, pH value and metal ions (Hg2+ or Fe3+), which renders them great potential as sensors. More interestingly, the NCDs exhibit certain photocatalytic activity on MO degradation and can enhance the activity of TiO2, which means the NCDs may be a good sensitizer for photocatalyst.
Thesis (PhD Doctorate)
Doctor of Philosophy (PhD)
Griffith School of Engineering
Science, Environment, Engineering and Technology
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Pierre, Le Brun Anton. "Nanoscale structure of membrane protein arrays." Thesis, University of Newcastle Upon Tyne, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.500907.

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Electron microscopy and atomic force microscopy can provide structural information on the surface of a membrane and spectroscopic techniques tell us about the structure and dynamics i integral membrane proteins. However none of these techniques relate to what is happenmg in the 5 to 6 nm thick layer under the surface of the membrane. Only reflection methods can provide information about the distribution of materials on the axis perpendicular to the membrane surface (the z-axis). Neutron scattering can discriminate between hydrogen and its isotope deuterium, making neutron reflection a powerfiil tool for dissecting how lipid, protein and solvent relate to one another along the z-axis and providing a method in which certain components can be highhghted or made invisible by choosing the correct solvent contrast. This data helped in the design of new antibody-binding biosensors that have a greater efficiency for antibody binding and greater stability for transportation.

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Gangmei, Prim. "Magnetisation dynamics of nanoscale magnetic materials and spintronics." Thesis, University of Exeter, 2012. http://hdl.handle.net/10036/3502.

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The magnetisation dynamics of a single square nanomagnet, the interaction between a pair of nanodiscs, a partially built writer structure and a range of magnetic tunnel junction sensor heads were studied using Time Resolved Scanning Kerr Microscopy (TRSKM) and four probe contact DC electrical transport measurements. Large amplitude magnetisation dynamics of a single square nanomagnet have been studied by TRSKM. Experimental spectra revealed that only a single mode was excited for all bias field values. Micromagnetic simulations demonstrate that at larger pulsed field amplitudes the center mode dominates the dynamic response while the edge mode is almost completely suppressed. The magnetisation dynamics occurring in a system comprised of two laterally separated magnetic nano-discs were also investigated. The polar Magneto-Optical Kerr Effect was used to measure the dynamic response of each disc independently so as to demonstrate that dynamic dipolar interactions between non-uniform spin wave modes in the different discs may be identified from the difference in their phase of oscillation. Results show a stronger dynamic dipolar interaction than expected from micromagnetic simulations highlighting both the need for characterisation and control of magnetic properties at the deep nanoscale and the potential use of dynamic interactions for the realization of useful magnetic nanotechnologies. TRSKM measurements were made simultaneously of the three Cartesian components of the magnetisation vector, by means of a quadrant photodiode polarisation bridge detector, on partially built hard disk writer structures. The rise time, relaxation time, and amplitude of each component has been related to the magnetic ground state, the initial torque, and flux propagation through the yoke and pole piece. Dynamic images reveal “flux-beaming” in which the magnetisation component parallel to the symmetry axis of the yoke is largest along that axis. A comparison of the magnetisation dynamics excited with different pulsed excitation amplitudes was also made. The results shows that more effective flux beaming is observed for higher pulse amplitudes. Lastly the microwave emission of Tunnel Magnetoresistance (TMR) nanopillars has been measured using a four probe contact DC electrical transport measurement technique as a magnetic field is applied in the plane of the film at different angles (ϕ_H ) with respect to the easy axis. Experimental spectra revealed that a more complicated spectrum containing several modes is observed as ϕ_H is increased. The modes were identified as edge and higher order modes from the statistical distribution of modes from different devices and micromagnetic simulations. The in-plane and out-of-plane components of the Spin Transfer Torque (STT) were estimated by analytical fitting of experimental data for the lowest frequency edge mode for the value of ϕ_H where the amplitude of the said mode was a maximum and its frequency a minimum. The estimated values are larger than expected perhaps due to the macrospin approximation made in deriving the analytical model. The results presented in this thesis can contribute to the understanding of magnetisation dynamics in industrially relevant data storage devices as well as the realization of a dipolar field coupling mechanism for arrays of nanooscillators.

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Dougan, Jennifer Anne. "Modified oligonucleotides for the functionalisation of nanoscale materials." Thesis, University of Strathclyde, 2009. http://oleg.lib.strath.ac.uk:80/R/?func=dbin-jump-full&object_id=14361.

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Li, Mei. "Synthesis, organization and characterization of nanoscale inorganic materials." Thesis, University of Bristol, 2000. http://hdl.handle.net/1983/9838d282-a46c-4e5b-b61d-6f4a883bc632.

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Ihalawela, Chandrasiri A. "Sb-Te Phase-change Materials under Nanoscale Confinement." Ohio University / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1449245846.

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Wolf, Daniel, and Christian Kübel. "Electron Tomography for 3D imaging of Nanoscale Materials." Carl Hanser Verlag, 2018. https://slub.qucosa.de/id/qucosa%3A33863.

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Over the last two decades, electron tomography, the combination of tomographic methods and transmission electron microscopy (TEM), has considerably contributed to provide new insights into the three-dimensional structure of nanoscale materials. In particular, emerging advances in nanoscience are inevitably linked to developments in quantitative two-dimensional (2D) and three-dimensional (3D) TEM characterization techniques. In many cases, ET is employed to reconstruct the 3D shape (faceting of crystals) and the distribution or the arrangement (assembly) of nanoparticles down to the nanometer and atomic scale. Moreover, it is used to reconstruct the full 3D morphology of complex nanomaterials and composites, which can be evaluated further as a basis for quantitative modelling of physical properties. Beyond these capabilities, ET reveals the 3D chemical composition of nanostructures by combining it with spectroscopic methods, such as, electron energy-loss spectroscopy (EELS) and energy-dispersive X-ray spectroscopy (EDS). In specific cases, ET applied together with electron holography enables reconstructing electrostatic potentials in 3D, for example space-charge related diffusion potentials at pn-junctions in semiconductors. In ferromagnetic materials, this approach also allows for the 3D reconstruction of the internal remanent magnetic induction (B-field).

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Balakishan, Harishankar. "Nanoscale Tomography Based in Electrostatic Force Microscopy." Doctoral thesis, Universitat de Barcelona, 2021. http://hdl.handle.net/10803/671789.

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The ability to characterize the elements beneath the surface has been a dire necessity in the fields of materials science, polymer technology, biology, and medical sciences. Scanning Probe Microscopies are the family of microscopies that scans the surface using a nanometric probe and the acquired data is used to reconstruct the physical properties of the samples in nanometric resolution (e.g., topography). Since the measurements could be carried out in non-contact mode, the ability to study tomography have made them a better contender. SPM also possess the relative advantage of being non-invasive, non-destructive, requires relatively minimal sample preparation, can be extended into any environment (inert, ambient vacuum), and also be measured in air, water, or any biological medium. Among them, Electrostatic Force Microscopy, has been successfully used in subsurface investigations to study the compositional modifications below the organic layers, imaging below the organic layers, imaging water molecules in confined nanometric channels, imaging of carbon nanotubes, graphene networks and nanoparticles inside the polymeric nanocomposites. Nanocomposites, which consist of nanostructures in their bulk matrix to improve the matrix efficiency, have been one of the successfully incorporated material science application of the last two decades. Silver nanoparticle especially have a barrage of applications to its credit ranging from solar cell applications, touch screens, LEDs to flexible wearable devices. Understanding the subsurface features or tomography of these nanocomposites could help us in understanding their properties, interpreting them based on their parametric dependence which would later aid us in tuning them for our desired applications. In this thesis. Individual computational studies have been carried out of nanowires buried in a dielectric matrix to observe the effects of various parameters influencing the subsurface imaging. Spatial resolution is given prime importance as its behavior of two parallel nanowires is studied along with two nanowires overlapped one on top of each other. Also, the analysis of silver nanowire nanocomposites has been investigated with the help of Scanning Dielectric Force Volume Microscopy, a technique proposed recently with EFM. The bulk matrix is composed of gelatin which can offer a range of permittivities depending on the degree of hydration, for e.g., here εr ~ 5 to εr ~ 14 . This sample is experimentally analyzed, imaged and the depth of nanowires in the matrix inside the bulk matrix is mapped with the theoretical analysis. This thesis research provides us with subsurface information that would help us in understanding and tuning the parameters to achieve desired applications.
La capacidad de caracterizar los elementos debajo de la superficie ha sido una necesidad imperiosa en los campos de la ciencia de los materiales, la tecnología de polímeros, la biología y las ciencias médicas. La microscopía de sonda de barrido (SPM por sus siglas en inglés) es una técnica de microscopía que permite exploran la superficie de una muestra a nano escala utilizando una sonda nanométrica, donde los datos adquiridos se utilizan para reconstruir las propiedades físicas de las muestras en resolución nanométrica (por ejemplo, topografía). Dado que las mediciones se pueden realizar sin contacto, los diferentes tipos de SPM se han convertido en candidatos óptimos para el estudio de propiedades sin necesidad de destruir la muestra. El SPM también posee la ventaja relativa de ser no invasivo, no destructivo, requiere una preparación de muestra relativamente sencilla, puede extenderse a cualquier ambiente (inerte, vacío ambiental), y también medirse en aire, agua o cualquier medio biológico. Entre ellos, la microscopía de fuerza electrostática, se ha utilizado con éxito en investigaciones del subsuelo para estudiar las modificaciones de composición debajo de las capas orgánicas, obtener imágenes debajo de las capas orgánicas, obtener imágenes de moléculas de agua confinada en canales nanométricos, imágenes de nanotubos de carbono, redes de grafeno y nanopartículas dentro de polímeros. Los nanocompuestos, que consisten en nanoestructuras en gran parte de su matriz para mejorar la eficiencia de la matriz, han sido una de las aplicaciones de la ciencia de materiales incorporadas con éxito en las últimas dos décadas. Las nanopartículas de plata tienen especialmente un aluvión de aplicaciones en su haber que van desde aplicaciones de células solares, pantallas táctiles, LED hasta dispositivos portátiles flexibles. Comprender las características del subsuelo o la tomografía de estos nanocompuestos podría ayudarnos a comprender sus propiedades, interpretándolas en función de su dependencia paramétrica, lo que luego nos ayudaría a ajustarlos para otras aplicaciones. En esta tesis, se han realizado estudios computacionales individuales de nano cables enterrados en una matriz dieléctrica para observar los efectos de varios parámetros que influyen en las imágenes del subsuelo. La resolución espacial tiene una importancia primordial, ya que se estudia su comportamiento de dos nano cables paralelos junto con dos nano cables superpuestos uno encima del otro. Además, el análisis de nanocompuestos de nano cables de plata se han investigado con la ayuda de la microscopía de barrido volumen de fuerza dieléctrica, una técnica propuesta recientemente con el EFM. La mayor parte de la matriz está compuesta de gelatina que puede ofrecer un rango de permitividades dependiendo del grado de hidratación, por ejemplo, aquí εr ~ 5 a εr ~ 14. Esta muestra se analiza experimentalmente, se obtienen imágenes y la profundidad de los nano cables en la matriz se mapean con el análisis teórico. Esta tesis nos proporciona nueva información y técnicas avanzadas a nivel tomográfico que ayudaran a la realización de imágenes de nanoestructuras de nuevos nanomateriales para aplicaciones en Salud y Electrónica.

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Roigé, Godia Abel. "Nanoscale spatially-resolved characterization of photovoltaic devices and materials." Doctoral thesis, Universitat Autònoma de Barcelona, 2015. http://hdl.handle.net/10803/287990.

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La tecnologia solar i fotovoltaica ha experimentat un important creixement durant els últims anys, i es preveu que sigui una de les principals fonts d'energia en un futur proper. Aquest creixement està relacionat amb una reducció significativa dels costos de producció i fabricació, així com amb una important evolució dels dispositius fotovoltaics que ha originat un increment en l'eficiència de les actuals cèl·lules solars. En el context del desenvolupament de nous dispositius fotovoltaics, la caracterització de materials es considera una tasca determinant. Així, tenint en compte que els dispositius fotovoltaics evolucionen cap a sistemes més prims i estructures més petites, les tècniques de caracterització d'alta resolució representen un paper rellevant en l'evolució i desenvolupament de la tecnologia solar i fotovoltaica. En el present treball, s’utilitzen diferents tècniques de caracterització d'alta resolució per estudiar determinades característiques de dispositius solars basats en silici cristal·lí. Entre les tècniques utilitzades trobem la microscòpia per sonda kelvin, l’espectroscòpia Raman i l’espectroscòpia de fotoluminescència. En concret, el treball es centra fonamentalment en l'estudi de capes de passivació superficial, així com en l'estudi de contactes elèctrics locals processats mitjançant tecnologia làser. L'elevada resolució de les tècniques de caracterització utilitzades en aquest treball ens permet accedir a informació única i exclusiva sobre certes propietats dels sistemes i materials estudiats. D'aquesta manera, la informació obtinguda representa la base per optimitzar i millorar els dispositius fotovoltaics actuals. En la part final del treball, les mateixes tècniques experimentals s'utilitzen per estudiar l'ordenament molecular de diferents capes orgàniques utilitzades en dispositius fotovoltaics d’última generació. Els sistemes fotovoltaics orgànics mostren atractives propietats com flexibilitat i baix cost, les quals posicionen a aquests sistemes com possibles candidats per un ampli ventall de noves aplicacions. Amb aquest últim estudi es vol demostrar la versatilitat i potencial de les tècniques experimentals utilitzades en aquest treball per a l'estudi de materials i dispositius fotovoltaics.
Photovoltaic (PV) technology has experienced a tremendous growth during recent years, and PV energy is expected to be one of the main energy sources in the future. This growth has been induced by a drastic reduction of production costs, and an important evolution of solar cell technology that has lead to an increase of solar cells efficiency. In the context of device evolution, material and device characterization becomes an important task to further explore novel PV systems and architectures. Since ultimate PV technologies progressively move towards thinner devices and smaller structures, characterization techniques with high spatial resolution play an important role for the further technological development of the PV field. In this work, we apply different high-resolution advanced characterization techniques such as Kelvin Probe Force Microscopy (KPFM), micro-Raman and micro-Photoluminescence (PL) to carry out a comprehensive study of crystalline silicon (c-Si) PV devices. In particular, the work is focused on the analysis of rear surface passivation layers and local base contacts processed by laser, which are key features of ultimate c-Si PV architectures. The high-resolution capabilities of such experimental techniques allow obtaining unique and exclusive information about material properties and device operation. In this sense, the obtained information represents the foundations to improve and optimize the current PV devices and technology. In the final part of the work, we apply the same experimental techniques to study the molecular distribution across organic PV (OPV) thin films. OPV systems show attractive properties like low cost and flexibility, which make them suitable candidates for a broad range of novel application possibilities. With this last study we intend to demonstrate the versatility and applicability of the used characterization techniques for studying a wide range of PV materials and devices.

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Wittborn, Jesper. "Nanoscale studies of functional materials using scanning probe microscopy." Doctoral thesis, KTH, Materials Science and Engineering, 2000. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-3000.

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This thesis deals with developing suitable modifications ofScanning Probe Microscopy (SPM) for investigations offunctional properties of materials. In order to make itpossible to investigate a number of properties of variousfunctional systemsusing SPM the following new techniques have beendeveloped:

A magnetic force microscope (MFM) having capability ofboth dc- and ac-mode detection.

A method to extract switching field distributions fromseries of MFM images.

A novel technique for magnetic microscopy using anon-magnetic probe to investigate the magnetostrictiveresponse of ferromagnetic materials, capable of 1 nmresolution.

A technique to determine the magnetostriction at lowexternal fields using AFM.

A technique for AFM studies of ferroelectric domainsusing the inverse piezoelectric effect of ferroelectricmaterials.

A technique for studying the relative stiffnessdistribution in composite materials using AFM.

Scanning friction microscopy.

Methods for determining the structure ofnanoindents.

Using the techniques highlighted above, we have studiedfunctional materials of current interest from bothtechnological and basic research points of view. Some of the materials and the main results obtainedare:

The role of magnetism arising from chains of nano-sizedmagnetite particles bio-mineralized in magneto-tacticbacteria is a topic of growing interest today. We use MFMtechniques to investigate magnetic flux reversal phenomena insuch chains. It is found that:

1.2.It is noteworthy that from our MFM measurements on singlemagnetosomes of 50 nm we havedetected magnetic moments as small as 3.1·10-14emu. Such detection is not possible by anyother technique known today.

1.2.

1.

2.

It is noteworthy that from our MFM measurements on singlemagnetosomes of 50 nm we havedetected magnetic moments as small as 3.1·10-14emu. Such detection is not possible by anyother technique known today.

Evaluation of magnetostrictive properties of smallstructures is extremely important and relevant to informationstorage media and read/write heads, in particular, as storagedensities beyond 30 gigabytes is pursued. In this thesis astudy of domain wall width of submicron man-made Co dots ispresented with a newly developed magnetostrictive imagingtechnique. Domain wall width of ~35 nm have been observed inmagnetic dots of 250 nm diameter. Additionally, we found thatdue to magnetostatic coupling the dots influence theneighboring domains to align ferromagnetically. The studiespresented herein are the first such to be reported inliterature.

From an investigation of epitaxially grown ferroelectricPbZr_0.65Ti_0.35O₃(PZT) thin films the existence of orderedpolydomain configurations in grains larger than 200 nm aredemonstrated.

For an understanding of the interaction between thecomponents of composite materials the relative stiffness wasdetermined for a composite material consisting of TiNinclusions in an Al₂O₃matrix. This would be a new approach to studythe local mechanical properties of future nano-compositematerials.

Preliminary investigations of the structure of nanoindentson a variety of materials demonstrate potentially richpossibilities to study the hardness at various depths inadvanced nanostructured materials

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36

Hooton, Jennifer Claire. "The nanoscale characterization and interparticulate interactions of pharmaceutical materials." Thesis, University of Nottingham, 2003. http://eprints.nottingham.ac.uk/10047/.

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The aim of this project is to compare pharmaceutical particles made using a Nektar supercritical fluid technology technique called solution enhanced dispersion by supercritical fluids (SEDSTM) to those made using more traditional techniques. This involves a comparison of not only the surface properties of both types of particles, but also the interparticulate interactions. The majority of the work has involved the use of the atomic force microscope (AFM) as both a tool for imaging and for the acquisition of localized force measurements. The first experimental chapter of this work describes a method developed in order to image the contacting asperities of a particle. The AFM has the potential to provide useful information regarding single particle interactions to complement data generated from bulk techniques. In this chapter, the AFM artefact of tip imaging was used to produce 3D images of the asperities of particles of micronised and SEDSTM salbutamol sulphate, an anti-asthma drug, contacting a model surface of highly orientated pyrolytic graphite (HOPG). These data were recorded in a model propellant environment, used in order to simulate the environment that would be found in pressurised metered dose inhalers, such as those used by asthmatics. From the images generated the contacting area was estimated to be 1.1x10-3 mm2 for the micronised material, and 1.4x10-3 for the SEDSTM material. The work of adhesion for both of the materials was also calculated, and the values of 19.0 mJm-2 and 4.0 mJm-2 were obtained for the micronised and SEDSTM samples respectively. This supported available data that indicated the SEDS material had a lower surface energy than the micronised drug, and that it is possible to make comparisons between different modified AFM probes. The second chapter develops this work so that it can be applied to an air environment, which is applicable to more pharmaceutical systems. Here, force measurements were again performed using AFM, with the same drug samples studied in the first chapter, except a controlled relative humidity (RH) environment was used, so that the variation in adhesion with increasing RH could be studied. Two types of measurement were undertaken. The first involved the use of blank AFM tips on compressed disks of drug material, and the second involved the use of drug particles mounted onto AFM tips on both HOPG and compressed disks of drug. With the blank AFM tip and particle modified AFM tip on HOPG work it was observed that the SEDSTM materials showed a peak in adhesion force at 22% RH while the micronised salbutamol showed a peak at 44% RH. From this, a three-scenario model of linking morphology of contact to adhesion was developed to explain the observed peaks in adhesion. In addition, the surface energies of each of the two samples were calculated using the force measurements acquired against HOPG and compressed disks of material and compared. The micronised material was found to have a higher surface energy than the SEDSTM material (10.8 mJm-2 cf 5 mJm-2) when data acquired against HOPG was used. However, when data acquired using the compressed disks of drug were used, the SEDSTM had a higher surface energy than the micronised (29.9 mJm-2 cf 22.6 mJm-2). This higher value was attributed to different surface roughness effects found with the compressed disks. The third chapter uses the techniques and models developed in the previous chapters to examine the effect of polymorphism on surface energy, structure and particulate interactions. Three polymorphs of the drug sulphathiazole (forms I, II and IV) were formed using the SEDSTM technique, one of which (form I) was formed using two different solvents: methanol and acetone. Force measurements were performed using the AFM at controlled humidity using particles of each of the polymorphs mounted onto AFM tips against substrates of HOPG and the polymorph under analysis. This data was then related to the model developed in the previous chapter, and calculations were undertaken to assess the different surface energies of each of the four samples. For some of the samples it was observed that peaks were again occurring in the data, at 22% RH for polymorphs I-methanol and III, and 44% for polymorph IV. No peak was seen for polymorph I-acetone. These peaks were then related to the surface energy calculated for each of the polymorphs, as polymorphs I-methanol and III were found to have lower surface energy (0.99 mJm-2 and 1.17 mJm-2 respectively) than polymorphs IV and I-acetone (20.33 mJm-2 and 309 mJm-2). The fourth chapter examines the application of AFM to an industrial problem. When using the SEDSTM process to manufacture insulin, it was observed that the SEDSTM material had poorer flow properties than that of the unprocessed material. Using the AFM as both an imaging and force measurement tool, this chapter explores the application of imaging and the adhesion models and surface energy calculations previously developed to understand this problem. The AFM images showed the presence of highly aggregated particles of SEDSTM insulin, compared to the unprocessed insulin that appeared to be more crystalline. When force measurements were performed against both HOPG and particles of the material under analysis, non of the unprocessed, and only one of the SEDSTM particle tips prepared displayed the peak behaviour seen with previous measurements, and instead displayed a continual increase in adhesion force with humidity. In addition, when the surface energy was calculated, the SEDSTM material was found to be higher than the unprocessed insulin (77.5 mJm-2 cf 2.4 mJm-2). The increase in adhesion force was related to the particles agglomerating together, due to the presence of a higher surface energy and high amorphous content of the particles. The final experimental chapter uses techniques that compliment AFM analysis to examine another industrial problem. The SEDSTM process can be used to co-formulate drugs with other materials such as polymers. In this chapter, the drug pregabalin has been co-formulated with lipid in order to produce a coating around the drug to mask taste. The use of AFM as an imaging tool, and the additional techniques of X-ray photoelectron spectrometry (XPS) and time-of-flight secondary ion mass spectroscopy (ToF-SIMS) have been used to generate an understanding of surface structure and chemistry of this heterogeneous system. The AFM images showed no areas of surface heterogeneous behaviour, although the largest scan size was only 5 mm x 5 mm. However both the XPS and ToF-SIMS spectra, which samples far larger areas (up to 75 mm x 75 mm) showed the presence of lipid and drug molecules. It was concluded that the lipid was not forming a uniform layer around the drug molecule, but was instead forming large patches that were beyond the resolution of the AFM. This work aims therefore to provide a fundamental study of the application of AFM to real pharmaceutical systems. In particular models are developed which allow not only ranking of particle interactions but the quantification of factors such as surface energy and work of adhesion. Finally the significance of the morphology of the inter-particulate contact has been explored at the nanoscale.

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37

Liao, Bolin Ph D. Massachusetts Institute of Technology. "Nanoscale electron, phonon and spin transport in thermoelectric materials." Thesis, Massachusetts Institute of Technology, 2016. http://hdl.handle.net/1721.1/104231.

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Thesis: Ph. D., Massachusetts Institute of Technology, Department of Mechanical Engineering, 2016.
Cataloged from PDF version of thesis.
Includes bibliographical references (pages 133-146).
Climate change is among the most critical challenges that are facing the human race in the 21st century. One of the major factors that leads to climate change is the increasing consumption of fossil fuels, driven by industrialization and economic growth at an unprecedented pace. For a secure and sustainable future of energy and the environment, new clean and efficient energy technologies are in urgent need. Thermoelectric materials are a group of materials that can directly convert heat into electricity. Being solid state, clean, reliable and without moving parts, thermoelectric energy conversion holds great promise as a candidate technology to harvest energy from thermal sources, such as the sun and terrestrial heat sources, as well as improve the efficiency of existing energy systems by recycling the inevitable waste heat. The bottleneck that prevents large-scale deployment of thermoelectric modules so far, however, is the relatively low efficiency and high cost. A good thermoelectric material needs to conduct electricity well and conduct heat poorly to attain high efficiency. Remarkable progress has been made in the past decade to decouple the charge and heat transport and thus improve the material performance. Most of the progress has been based on a more detailed understanding of the transport and interaction of fundamental energy carriers, such as electrons and phonons in most semiconductors, and magnons in magnetic materials. These understandings have been achieved through the development of both first-principles simulations and experimental spectroscopic tools, in particular for phonon transport and phonon-phonon interaction, which have enabled calculations and measurements at the single-phonon-mode level. Information gained from these studies formed the foundation of the successful engineering efforts of designing nanostructured thermoelectric materials. Although the nanostructuring approach has been able to reduce the thermal conductivity of thermoelectric materials down to proximity of the amorphous limit, it has been realized by the community that further improvement of thermoelectric materials requires breakthroughs in boosting the electrical transport properties, including the electrical conductivity and the Seebeck coefficient. Despite several existing strategies, a prerequisite for systematic improvement is, again, insight into the transport and interaction of fundamental carriers, particularly involving electrons, at the single-mode level. This insight has largely remained lacking in terms of electrons, both on the simulation side and on the experimental side. This thesis aims to develop both simulation and experimental tools to study nanoscale electron, phonon and magnon transport and their interactions, with a particular emphasis on understanding the electron-phonon interaction at the single-mode level. This is among the most important forms of carrier interactions and determines the intrinsic electron transport properties of most conductors. Regarding phonon transport, we applied first-principles lattice dynamics to study phonon-phonon interaction and lattice thermal conductivity in a strongly-correlated thermoelectric compound FeSb 2. On electronphonon interactions, we studied from first-principles the intrinsic electrical transport properties of phosphorene, which are limited by electron-phonon interactions, analyzed its anisotropy and evaluated its potential as a thermoelectric material; we studied how free carriers can in turn scatter phonons through the electron-phonon interaction and reduce the lattice thermal conductivity; to verify this finding, we designed an ultrafast photoacoustic spectroscopic technique to directly detect the damping of a single phonon mode due to electron-phonon interaction. On phonon-magnon interactions, we applied the coupled Boltzmann equation to analyze coupled phonon-magnon diffusion and proposed a novel magnon cooling effect. These fundamental discoveries can potentially lead to new design principles for more efficient thermoelectric materials in the future.
by Bolin Liao.
Ph. D.

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38

Che, Rose Laili. "Exploiting nanoscale materials properties for controlled drug delivery systems." Thesis, University of East Anglia, 2013. https://ueaeprints.uea.ac.uk/47950/.

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The main objective of this work was to develop a novel drug delivery system exploiting special opportunities afforded by synthesis of nanoscale materials to be applied inside the colon. It must be robust enough to cope with the adverse conditions in the gastrointestinal tract (GI) and be able to reach and release “on demand” at the colon area at the right time. In this work, an oral capsule formulation with iron oxide nanoparticles (IONs) containing coating was used to transport drug and release drug in the colon. With that in mind, the synthesis of poly (alkylcyanoacrylate) nanocapsules by microemulsion polymerisation and magnetic iron oxide nanoparticles (IONs) via a coprecipitation method were conducted. The key physical properties of the materials were characterized employing standard techniques such as HPLC, FTIR, DSC, DLS, XRD, TEM and SEM. Hard capsules filled with model drug, paracetamol, were coated with IONs containing coatings (fatty acids and paraffin). The optimum composition for the formulation of the coating embedded with the nanoparticles was explored with respect to protection of the drug payload from conditions in the GI tract as well as for effective release “on demand” using radio-frequency hyperthermia. The optimum radiofrequency and the power level for heating the nanoparticles were also determined and melting the coating using magnetic nanoparticle hyperthermia. Results showed that paraffin-based coatings had appropriate properties for this application. Finally, taking into account all the results, a design of a novel drug delivery system, together with an experimental setup for testing the “release in demand” was proposed. The approach is generic, easy to set up and could also be applied to many other situations where delivery on demand is required.

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39

Chauhan, Vinay Singh. "Impact of Nanoscale Defects on Thermal Transport in Materials." The Ohio State University, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=osu1586440154974469.

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40

Scott, William Walter Jr. "Micro/Nanoscale Differential Wear and Corrosion of Multiphase Materials." The Ohio State University, 2001. http://rave.ohiolink.edu/etdc/view?acc_num=osu994420446.

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41

Incorvia, Jean Anne Currivan. "Nanoscale Magnetic Materials for Energy-Efficient Spin Based Transistors." Thesis, Harvard University, 2015. http://nrs.harvard.edu/urn-3:HUL.InstRepos:17467318.

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In this dissertation, I study the physical behavior of nanoscale magnetic materials and build spin-based transistors that encode information in magnetic domain walls. It can be argued that energy dissipation is the most serious problem in modern electronics, and one that has been resistant to a breakthrough. Wasted heat during computing both wastes energy and hinders further technology scaling. This is an opportunity for physicists and engineers to come up with creative solutions for more energy-efficient computing. I present the device we have designed, called domain wall logic (DW-Logic). Information is stored in the position of a magnetic domain wall in a ferromagnetic wire and read out using a magnetic tunnel junction. This hybrid design uses electrical current as the input and output, keeping the device compatible with charge- based transistors. I build an iterative model to predict both the micromagnetic and circuit behavior of DW- Logic, showing a single device can operate as a universal gate. The model shows we can build complex circuits including an 18-gate Full Adder, and allows us to predict the device switching energy compared to complementary metal-oxide semiconductor (CMOS) transistors. Comparing 15 nm feature nodes, I find DW-Logic made with perpendicular magnetic anisotropy materials, and utilizing both spin torque transfer and the Spin Hall effect, could operate with 1000× reduced switching energy compared to CMOS. I fabricate DW-Logic device prototypes and show in experiment they can act as AND and NAND gates. I demonstrate that one device can drive two subsequent devices, showing gain, which is a necessary requirement for fanout. I also build a clocked ring oscillator circuit to demonstrate successful bit propagation in a DW-Logic circuit and show that properly scaled devices can have improved operation. Through building the devices, I develop a novel fabrication method for patterning sub-25 nm magnetic wires with very low (~ 2 nm) average edge roughness. I apply the fabrication method to measuring the Spin Hall angle in epitaxially grown thin films and to studying the repeatability of domain wall motion in narrow wires. I also present a number of modeling results, including the effect of edge roughness on both magnetic tunnel junctions and domain walls.
Physics

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42

Scott, William Walter. "Micro/nanoscale differential wear and corrosion of multiphase materials /." Connect to this title online, 2001. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu994420446.

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Thesis (Ph. D.)--Ohio State University, 2001.
Advisor: Bharat Bhushan, Dept. of Mechanical Engineering. Includes bibliographical references (leaves 145-152). Available online vai OhioLINK's ETD center.

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43

Yen, Chun-Wan. "Plasmonic photochemistry on the nanoscale." Diss., Georgia Institute of Technology, 2011. http://hdl.handle.net/1853/41085.

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When nanoparticles are small in size compared to the wavelength of incident light, a localized surface plasmon resonance occurs. For certain noble metals, such as gold and silver, this frequency occurs in the visible or near IR range, and therefore it can be utilized for many important applications. Only silver and gold nanoparticles were utilized in this thesis work, and they were used in application for three separate files: environment, catalysis, and energy.

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44

Tian, Zhiting. "Nanoscale heat transfer in argon-like solids via molecular dynamics simuations." Diss., Online access via UMI:, 2009.

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Thesis (M.S.)--State University of New York at Binghamton, Thomas J. Watson School of Engineering and Applied Science, Department of Mechanical Engineering, 2009..
Includes bibliographical references.

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45

Ritchie, Kenneth Patrick. "Probing nanoscale adhesion and structure at soft interfaces." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp02/NQ34615.pdf.

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46

Evans, Matthew Hiram. "Nanoscale structure and transport : from atoms to devices." Thesis, Massachusetts Institute of Technology, 2005. http://hdl.handle.net/1721.1/32297.

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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Physics, 2005.
Includes bibliographical references (p. 145-159).
Nanoscale structures present both unique physics and unique theoretical challenges. Atomic-scale simulations can find novel nanostructures with desirable properties, but the search can be difficult if the wide range of possible structures is not well understood. Electrical response and other non-equilibrium transport phenomena are measured experimentally, but not always simulated accurately. This thesis presents four diverse applications that demonstrate how first-principles calculations can address these challenges. Novel boron nanotube structures with unusual elastic properties are presented. Internal degrees of freedom are identified that allow longitudinal stress to be dissipated without changing the tube's diameter, leading to high lateral stiffness. Self-trapped hole structures in amorphous silicon dioxide are investigated in order to connect the behavior of hole currents to atomic-scale structures. Calculations on a paired-oxygen analogue to the ... center show that such a configuration does not result in a metastable trapped-hole state. A novel method to enable first-principles mobility calculations in ultrathin silicon-on-insulator (UTSOI) structures is presented and applied to interface roughness scattering in transistor channels. Self-consistent potentials and accurate wavefunctions and band structures allow for a direct link between measured electrical response and atomic structure. Atomic-scale interface roughness is shown to be an important limit on mobility at high carrier densities. At low carrier densities, such short-wavelength roughness results in qualitatively different mobility behavior than gradual UTSOI channel thickness fluctuations.
(cont.) An effective Hamiltonian technique to calculate short-time, non-equilibrium fluctuations in quantum devices is developed. Applications to quantum dots and resonant tunneling diodes show that temporal fluctuations are reproduced well.
by Matthew Hiram Evans.
Ph.D.

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47

Macias, Celia Edith 1982. "Nanoscale properties of poly(ethylene terephthalate) vascular grafts." Thesis, Massachusetts Institute of Technology, 2004. http://hdl.handle.net/1721.1/32727.

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Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 2004.
Includes bibliographical references (leaves 46-48).
Vascular grafts are prosthetic tubes that serve as artificial replacements for damaged blood vessels. Poly(ethylene-terephthalate), PET, has been successfully used in large diameter grafts; however, small caliber grafts are still a major challenge in biomaterials. Due to surface forces, blood plasma proteins adsorb to the graft, resulting in inflammation, infection, thrombus formation, and ultimately, vessel reclosure. The object of this project was to characterize and analyze the nanoscale surface properties of three different commercial vascular grafts, woven collagen-coated, knitted collagen- coated, and knitted heparin-bonded, all PET-based. The study was performed in order to ascertain differences in biocompatibility due to surface coating and morphology. Scanning Electron Microscopy, Atomic Force Microscopy and High Resolution Force Spectroscopy techniques were used to characterize the surface of the samples as well as to measure the forces between these surfaces and blood plasma proteins. The results will serve as a basis for the understanding of the nanoscale interactions between the biomaterial and blood plasma proteins. Such interactions are brought about by the different surface topologies and components, therefore a thorough understanding of surface properties will act as a building block for further changes in small caliber vascular grafts in order to enhance their biocompatibility.
by Celia Edith Macias.
S.B.

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48

Sines, Paul B. "Fabrication of thin film nanoscale alumina templates." Morgantown, W. Va. : [West Virginia University Libraries], 2001. http://etd.wvu.edu/templates/showETD.cfm?recnum=2183.

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Thesis (M.S.)--West Virginia University, 2001.
Title from document title page. Document formatted into pages; contains vii, 44 p. : ill. (some col.). Vita. Includes abstract. Includes bibliographical references (p. 35-37).

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49

Estradé, Albiol Sònia. "Electron Energy Loss Spectroscopy Solutions for Nanoscale Materials Science Problems." Doctoral thesis, Universitat de Barcelona, 2009. http://hdl.handle.net/10803/662847.

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In the Transmission Electron Microscope (TEM), an incident electron suffers both elastic and inelastic scattering by the solid state thin sample that is being characterised. In the event of inelastic scattering, the incident electron gives a part of its energy to the electrons in the sample. The amount of lost energy can then be measured by a magnetic filter at the end of the column, and a plot displaying how many electrons have lost what amount of energy will give us an Electron Energy Loss (EEL) Spectrum. Thus, in an EEL Spectrum the ordinate axis corresponds to the number of electrons, or counts, and the abscise corresponds to the Energy Loss. Notice that most electrons shall not suffer any inelastic scattering whatsoever. As a consequence, the greatest contribution to the spectrum is due to these electrons having lost zero energy, giving rise to the so-called zero loss peak (ZLP). As for those electrons having lost a certain amount of energy, they may lose it to ionization of specimen electrons, transitions from occupied core states to unoccupied core states or to conduction band states, to interband transitions or excitations of collective vibrations of conduction band electrons. Incident electrons carry a given momentum, and it is worth keeping in mind that in an inelastic scattering event not only energy, but also momentum, may be transferred. In fact, this is the reason why it is not straightforward to compare EELS results with those obtained by means of optic spectroscopies. EELS detectors can provide an energy resolution down to the order of the 0.1 eV. In addition, incident electrons can be tuned by TEM optics, making it possible to get spectroscopic information from an extremely constrained area, and to combine EEL Spectroscopy with TEM imaging.
En el microscopi electrònic de transmissió (TEM), un electró incident sofreix tant xocs elàstics com inelàstics en travessar la mostra prima d’estat sòlid que s’està caracteritzant. En cas de xoc inelàstic, l’electró incident cedeix part de la seva energia als electrons de la mostra. La quantitat d’energia perduda es pot mesurar amb un filtre magnètic situat al final de la columna, i un gràfic que indiqui quants electrons han perdut quina quantitat d’energia ens donarà un espectre de pèrdua d’energia dels electrons, o espectre EELS. Així, en un espectre EELS l’ordenada correspon al número d’electrons, o comptes, i l’abscissa, a la pèrdua d’energia. Avui en dia l’EELS s’ha convertit en un instrument crucial a la ciència de materials, per causa de la progressiva reducció de l’escala característica implicada en el desenvolupament d’aquesta disciplina, i també gràcies a la millora instrumental que ha tingut lloc en els darrers anys tant en la microscòpia electrònica en general com en l’EELS en particular. En aquesta tesi, s’han explorat les capacitats de l’EELS com a eina de caracterització de mostres d’estat sòlid a la nanoescala, i s’han aplicat a diversos problemes de ciència de materials.

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Graham, John F. "Quantitative nanoscale studies of materials by interfacial force microscopy (IFM)." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape7/PQDD_0008/NQ40260.pdf.

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Dissertations / Theses on the topic 'Nanoscale materials and structure'

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