Tesis sobre el tema "Nanoscience"
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Mas, Elodie A. "Exploiting kinetics in nanoscience". Thesis, University of Bristol, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.440269.
Texto completoLai, Massimo. "Computational nanoscience and multiscale modeling of DNA molecules". Thesis, Cranfield University, 2010. http://dspace.lib.cranfield.ac.uk/handle/1826/5556.
Texto completoMadden, Andrew Stephen. "Nanoscience Meets Geochemistry: Size-Dependent Reactivity of Hematite". Diss., Virginia Tech, 2005. http://hdl.handle.net/10919/28033.
Texto completoPh. D.
Wartelle, Alexis. "Mouvement de parois de domaines magnétiques dans des nanofils cylindriques modulés". Thesis, Université Grenoble Alpes (ComUE), 2018. http://www.theses.fr/2018GREAY025/document.
Texto completoThe thesis is concerned with the observation of ferromagnetic domain walls in cylindrical nanowires, as well as their dynamics under applied magnetic fields. These nanostructures were electrodeposited by colleagues of mine into nanoporous alumina templates with a tailored pore geometry. The materials are soft FeNi or CoNi alloys; the diameters range from 150 nm to 250-300 nm, with a typical length of 30 µm.My work first comprised experimental developments of sample holders and high-frequency electronics towards field-induced domain wall motion. The latter I investigated with X-ray Magnetic Circular Dichroism coupled to transmission PhotoEmission Electron Microscopy (XMCD-PEEM). This synchrotron-based technique allows to monitor the internal domain wall configuration before and after displacement; due to the stringent requirements of time-resolved XMCD-PEEM experiments in terms of reproducibility, the real-time dynamics is out of reach as of yet.The response of ferromagnetic domain walls to applied magnetic fields is notably characterized by their mobility, i.e. the ratio of attained velocity to field strength. In cylindrical nanowires, a novel ingredient emerges in the case of one domain wall type that is absent in flat strips: the Bloch point domain wall. Not only does this domain wall host a micromagnetic singularity, that is to say a point where magnetization vanishes (the Bloch point), but it also possesses a discrete degree of freedom representing the sense of magnetization winding around the nanowire axis. It has been predicted that Bloch point wall motion under sufficiently high fields leads to this degree of freedom selecting one of its only two possible values. In other words, one winding becomes unstable. I report in this thesis experimental evidence of such a selection in a majority of Bloch point wall motion events.Although mobility measurements could not be carried out, my experiments have furthermore evidenced transformations between domain wall types that had not been predicted in simulations. Since the Bloch point wall contains a topological defect (the Bloch point itself), this unexpected behaviour questions the sometimes argued protection attributed to topologically non-trivial textures. While reminiscent of the well-known conversion between transverse and vortex walls in strips, these transformations in cylindrical nanowires involve topologically non-equivalent micromagnetic configurations, in contrast with the aforementioned transverse and vortex walls. Moreover, the observed only relative stability of domain wall types suggests caution in the interpretation of future mobility measurements in such systems, if the internal wall configuration cannot be resolved.Aside from such electrodeposited samples, I have also studied an upright core-shell nanowire grown by colleagues with Focused-Electron-Beam-Induced Deposition. This nanostructure featured a nanocrystalline cobalt core and a platinum shell. Its magnetic configuration was investigated with transmission XMCD-PEEM as well. Contrary to the aforementioned horizontally-lying wires, the core-shell sample was vertical with no diameter modulations. On the other hand, the geometry featured bends engineered to favour domain wall pinning. In this novel imaging configuration, the challenge was to recover as much of the nanowire's magnetic state as possible. I was able to demonstrate the presence of at least one domain wall
Altass, Hatem. "HCl nanoscience at copper and copper/gold alloy surfaces". Thesis, Cardiff University, 2013. http://orca.cf.ac.uk/50823/.
Texto completoLechuga, Javier. "Computational nanoscience of flow and mass transport through biological membranes". Thesis, Cranfield University, 2008. http://hdl.handle.net/1826/3495.
Texto completoAtkinson, Sarah Jane y n/a. "Studies in Dendritic Scaffolds and Surface Functionalisation for Applications in Nanoscience". Griffith University. School of Biomolecular and Physical Sciences, 2007. http://www4.gu.edu.au:8080/adt-root/public/adt-QGU20071122.124705.
Texto completoLai, Polly Kuan-Ling. "Learning Nanoscience From A Nanoparticle’s Perspective: A Computationally Embodied Learning Experience". Thesis, The University of Sydney, 2016. http://hdl.handle.net/2123/16406.
Texto completoAtkinson, Sarah Jane. "Studies in Dendritic Scaffolds and Surface Functionalisation for Applications in Nanoscience". Thesis, Griffith University, 2007. http://hdl.handle.net/10072/366865.
Texto completoThesis (PhD Doctorate)
Doctor of Philosophy (PhD)
School of Biomolecular and Physical Sciences
Full Text
Cooper, Rose. "Behavior of Gold Nanoparticles in Physiological Environment and the Role of Agglomeration and Fractal Dimension". Wright State University / OhioLINK, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=wright1440168780.
Texto completoYang, Lingyu. "In-Situ Synthesis of Well-Defined Silver Nanoparticles in Water Soluble Polymer Matrix". Case Western Reserve University School of Graduate Studies / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=case1555418297166208.
Texto completoGerngross, Lindsey. "TARGETING CFMS SIGNALING TO RESTORE IMMUNE FUNCTION AND ERADICATE HIV RESERVOIRS". Diss., Temple University Libraries, 2015. http://cdm16002.contentdm.oclc.org/cdm/ref/collection/p245801coll10/id/286848.
Texto completoPh.D.
While combination anti-retroviral therapy (cART) has improved the length and quality of life of individuals living with HIV-1 infection, the prevalence of HIV-associated neurocognitive disorders (HAND) has increased and remains a significant clinical concern. The neuropathogenesis of HAND is not completely understood, however, latent HIV infection in the central nervous system (CNS) and chronic neuroinflammation are believed to play a prominent role. CNS-associated macrophages and resident microglia are significant contributors to CNS inflammation and constitute the chief reservoir of HIV-1 infection in the CNS. Previous studies from our lab suggest monocyte/macrophage invasion of the CNS in HIV may be driven by altered monocyte/macrophage homeostasis. We have reported expansion of a monocyte subset (CD14+CD16+CD163+) in peripheral blood of HIV+ patients that is phenotypically similar to macrophages/microglia that accumulate in the CNS as seen in post-mortem tissue. The factors driving the expansion of this monocyte subset are unknown, however, signaling through cFMS, a type III receptor tyrosine kinase (RTK), may play a role. Macrophage-colony stimulating factor (M-CSF), a ligand of cFMS, has been shown to be elevated in the cerebral spinal fluid (CSF) of individuals with the most severe form of HAND, HIV-associated dementia (HAD). M-CSF promotes a Macrophage-2-like phenotype and increases CD16 and CD163 expression in cultured monocytes. M-CSF has also been shown to increase the susceptibility of macrophages to HIV infection and enhance virus production. These findings, in addition to the known function of M-CSF in promoting macrophage survival, supports a role for M-CSF in the development and maintenance of macrophage viral reservoirs in tissues where these cells accumulate, including the CNS. Interestingly, a second ligand for cFMS, IL-34, was recently identified and reported to share some functions with M-CSF, suggesting that both ligands may contribute to HIV-associated CNS injury and AIDS pathogenesis. Through immunohistochemical studies using a relevant animal model of HIV infection, SIV infected rhesus macaques, we reported the presence of M-CSF and IL-34 in the brains of seronegative and SIV+ animals, for the first time, and identified spatial differences in the expression of these ligands. Important to our interest in viral persistence in the CNS, we observed the predominance of M-CSF expression in brain to be by cells that comprise perivascular cuffs and nodular lesions, which contain monocytes/ macrophages that have migrated into the CNS. IL-34 appeared to be a tissue-specific ligand expressed by resident microglia. Like M-CSF, we found that IL-34 also increased the frequency of CD16+CD163+ monocytes in vitro. We further investigated the potential of cFMS inhibition as a means to abrogate macrophage-2-like immune polarization using the small molecule tyrosine kinase inhibitor (TKI), GW2580. The addition of GW2580 abolished cFMS ligand-mediated increases in CD16+CD163+ monocyte frequency in human peripheral blood mononuclear cells (PBMC) as well as virus production in HIV infected primary human microglia. Furthermore, we found cFMS-mediated upregulation of CD16 and CD163 to be relevant to an additional disease process, high-grade astrocytomas, suggesting that M-CSF and IL-34 may be mediators of other neuroinflammatory diseases, as well. We hope these findings will provide insight into the role of altered monocyte/macrophage homeostasis in HIV disease and identify a novel strategy for targeting long-lived cellular reservoirs of HIV infection through restored immune homeostasis.
Temple University--Theses
Sourmaidou, Damiani. "Computational nanoscience and molecular modelling of shock wave interactions with biological membranes". Thesis, Cranfield University, 2011. http://dspace.lib.cranfield.ac.uk/handle/1826/7283.
Texto completoPicco, Loren Michael. "Development and applications of a high-speed atomic force microscope for nanoscience". Thesis, University of Bristol, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.441668.
Texto completoHermelin, Sylvain. "Transport d'un électron unique dans des nanostructures". Phd thesis, Université de Grenoble, 2012. http://tel.archives-ouvertes.fr/tel-00721761.
Texto completoPeresutti, Romain. "Hélicènes et architectures polyaromatiques soufrés et glycosylés : applications en nanoscience et en biologie". Thesis, Aix-Marseille 2, 2011. http://www.theses.fr/2011AIX22132.
Texto completoPolysulfurated polyaromatic compounds represent a class of molecules that are not extensively studied, despite their interesting properties. The presence of sulfur affects their redox, photophysical and complexation properties. We prepared a series of these compounds by using some aromatic nucleophilic substitutions. They can be further functionalized by some polyaromatic units, such as anthracene or pyrene, or by some glycosides.Their luminescence properties have been especially studied for their agregation induced emission properties, where the emission of the compounds is turned on when they are immobilized in solid phase or strongly cooled. These compounds can also be used to stabilize iron/platinum nanoparticles, where a high density of divalent sulfur atoms play an important role in nanosciences. Glycosylated derivatives have been tested with different lectins like ConA, PAIL, PAIIL and Bc2lA, the last three being involved in bacterial infections found in patient suffering from cystic fibrosis. Studies include photophysical and reticulation properties, and also affinitiy assays by using biophysical methods (SPR, ITC, and HIA). It provided some novel biosensors or luminescent sensors based on some selective lectin-carbohydrate interactions, in the event of future diagnostic devices and biological detection originating from lectins expressions (ex. cancer, bacterial infection, etc.).Another class of polyaromatic compounds has been studied, the helicenes,. Those chiral helical molecules can be found under two enantiomeric forms, according to the sense of the helical pitch.We herein present a new synthetic method of helicenes based on an organometallic route for some annulation reactions and C-H insertions. An exhaustive study of reaction conditions has been performed. We have prepared some functionnalized helicenes. Brominated and cyanated [5]-helicene derivatives have been deposited on a Suzuki surface, in order to study their structuration properties by nc-AFM on a non conductive surface. [5]-helicene was further functionnalized with some mannosylated units, with the same perspectives as for the glycosylated sulfurated asterisks. Those glycosylated helicenes are the first of their kind described in the literature. They provided some adequate properties toward new chiral and luminescent sensors, as well as other biosensors, which are based on lectin-carbohydrate interactions
Peresutti, Romain. "Hélicènes et architectures polyaromatiques soufrés et glycosylés : applications en nanoscience et en biologie". Electronic Thesis or Diss., Aix-Marseille 2, 2011. http://www.theses.fr/2011AIX22132.
Texto completoPolysulfurated polyaromatic compounds represent a class of molecules that are not extensively studied, despite their interesting properties. The presence of sulfur affects their redox, photophysical and complexation properties. We prepared a series of these compounds by using some aromatic nucleophilic substitutions. They can be further functionalized by some polyaromatic units, such as anthracene or pyrene, or by some glycosides.Their luminescence properties have been especially studied for their agregation induced emission properties, where the emission of the compounds is turned on when they are immobilized in solid phase or strongly cooled. These compounds can also be used to stabilize iron/platinum nanoparticles, where a high density of divalent sulfur atoms play an important role in nanosciences. Glycosylated derivatives have been tested with different lectins like ConA, PAIL, PAIIL and Bc2lA, the last three being involved in bacterial infections found in patient suffering from cystic fibrosis. Studies include photophysical and reticulation properties, and also affinitiy assays by using biophysical methods (SPR, ITC, and HIA). It provided some novel biosensors or luminescent sensors based on some selective lectin-carbohydrate interactions, in the event of future diagnostic devices and biological detection originating from lectins expressions (ex. cancer, bacterial infection, etc.).Another class of polyaromatic compounds has been studied, the helicenes,. Those chiral helical molecules can be found under two enantiomeric forms, according to the sense of the helical pitch.We herein present a new synthetic method of helicenes based on an organometallic route for some annulation reactions and C-H insertions. An exhaustive study of reaction conditions has been performed. We have prepared some functionnalized helicenes. Brominated and cyanated [5]-helicene derivatives have been deposited on a Suzuki surface, in order to study their structuration properties by nc-AFM on a non conductive surface. [5]-helicene was further functionnalized with some mannosylated units, with the same perspectives as for the glycosylated sulfurated asterisks. Those glycosylated helicenes are the first of their kind described in the literature. They provided some adequate properties toward new chiral and luminescent sensors, as well as other biosensors, which are based on lectin-carbohydrate interactions
Mueanngern, Yutichai. "Mechanistic Study for Selective Hydrogenation of Crotonaldehyde Using Platinum/Metal-Oxide Catalysts—A Gas-Phased Kinetics Study". The Ohio State University, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=osu1462804731.
Texto completoPaluri, Sesha Lakshmi Arathi. "Analytical-based methodologies to examine In vitro nanokinetics of silver nanoparticles". Wright State University / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=wright1496146342673032.
Texto completoHenneke, Dale Edwin. "Nanoparticles produced via laser ablation of microparticles". Access restricted to users with UT Austin EID Full text (PDF) from UMI/Dissertation Abstracts International, 2001. http://wwwlib.umi.com/cr/utexas/fullcit?p3037496.
Texto completoChuang, Skylar T. "Apolipoprotein E3 Mediated Targeted Brain Delivery of Reconstituted High Density Lipoprotein Bearing 3, 10, And 17 Nm Hydrophobic Core Gold Nanoparticles". Thesis, California State University, Long Beach, 2017. http://pqdtopen.proquest.com/#viewpdf?dispub=10602927.
Texto completoWe have developed a high density lipoprotein (HDL)-based platform for transport and delivery of hydrophobic gold nanoparticles (AuNP). The ability of apolipoprotein E3 (apoE3) to act as a ligand for the low-density lipoprotein receptor (LDLr) was exploited to gain entry of HDL with AuNP into glioblastoma cells. AuNP of 3, 10 and 17 nm diameter, the latter two synthesized by phase transfer process, were solubilized by integration into reconstituted HDL (rHDL). Absorption spectroscopy indicated the presence of stable particles with signature surface plasmon bands, while electron microscopy revealed AuNP embedded in rHDL core. The rHDL-AuNP complexes displayed robust binding to the LDLr, were internalized by the glioblastoma cells, and appeared as aggregated AuNP in the endosomal-lysosomal compartments. The rHDL-AuNP generated little cytotoxicity and were able to cross the blood brain barrier. The findings bear significance since they offer an effective means of delivering AuNP across tumor cell membrane.
Deol, Suprit S. "Stability, cytotoxicity, and cell permeability of dendron-conjugated gold nanoparticles with 3, 12, and 17 nm core". Thesis, California State University, Long Beach, 2015. http://pqdtopen.proquest.com/#viewpdf?dispub=1590079.
Texto completoThis thesis describes the synthesis of water-soluble dendron-conjugated gold nanoparticles (Den-AuNPs) with various average core sizes and the evaluation of stability, cytotoxicity, and cell permeability and uptake of these materials. The characterization of Den-AuNPs using various instruments including transmission electron microscopy (TEM), matrix-assisted laser desorption/ionization-time of flight mass spectrometry (MALDI-TOF-MS), 1H NMR, FT-IR, and UV-vis spectroscopy confirms the dendron conjugation to the glutathione-capped gold nanoparticles (AuNPs). The stability of AuNPs and Den-AuNPs in solutions of different pH and salt concentration was determined by monitoring changes in surface plasmon bands of gold using UV-vis spectroscopy. The Den-AuNPs were found to be more stable than the precursor AuNPs maintaining their solubility at the pHs higher than 4 and with the salt concentrations of up to 100 mM. The improved stability of Den-AuNPs suggests that the post-functionalization of thiol-capped gold nanoparticle surfaces with dondrons can further improve the physiological stability and biocompatibility of gold nanoparticle-based materials. Cytotoxicity studies with AuNPs and Den-AuNPs with and without flourophores were also performed by examining cell viability for 3T3 fibroblasts using a MTT cell proliferation assay. The conjugation of dendrons to the AuNPs with flourophores was able to decrease the cytotoxicity brought about by the flourophores. The successful uptake of Den-AuNPs in mouse fibroblast 3T3 cells shows the physiological viability of the hybrid materials.
Birkner, Nancy R. "Thermodynamics of Manganese Oxides at Bulk and Nanoscale| Phase Formation, Transformation, Oxidation-Reduction, and Hydration". Thesis, University of California, Davis, 2015. http://pqdtopen.proquest.com/#viewpdf?dispub=3706557.
Texto completoNatural manganese oxides are generally formed in surficial environments that are near ambient temperature and water-rich, and may be exposed to wet-dry cycles and a variety of adsorbate species that influence dramatically their level of hydration. Manganese oxide minerals are often poorly crystalline, nanophase, and hydrous. In the near-surface environment they are involved in processes that are important to life, such as water column oxygen cycling, biomineralization, and transport of minerals/nutrients through soils and water. These processes, often involving transformations among manganese oxide polymorphs, are governed by a complex interplay between thermodynamics and kinetics. Manganese oxides are also used in technology as catalysts, and for other applications.
The major goal of this dissertation is to examine the energetics of bulk and nanophase manganese oxide phases as a function of particle size, composition, and surface hydration. Careful synthesis and characterization of manganese oxide phases with different surface areas provided samples for the study of enthalpies of formation by high temperature oxide melt solution calorimetry and of the energetics of water adsorption on their surfaces. These data provide a quantitative picture of phase stability and how it changes at the nanoscale.
The surface energy of the hydrous surface of Mn3O4 is 0.96 ± 0.08 J/m2, of Mn2O3 is 1.29 ± 0.10 J/m2, and of MnO2 is 1.64 ± 0.10 J/m2. The surface energy of the anhydrous surface of Mn3O4 is 1.62 ± 0.08 J/m 2, of Mn2O3 is 1.77 ± 0.10 J/m 2, and of MnO2 is 2.05 ± 0.10 J/m2. Supporting preliminary findings (Navrotsky et al., 2010), the spinel phase (Mn3O4) has a lower surface energy (more stabilizing) than bixbyite, while the latter has a smaller surface energy than pyrolusite. These differences significantly change the positions in oxygen fugacity—temperature space of the redox couples Mn3O4-Mn2O 3 and Mn2O3-MnO2 favoring the lower surface enthalpy phase (the spinel Mn3O4) for smaller particle size and in the presence of surface hydration.
Chemisorption of water onto anhydrous nanophase Mn2O 3 surfaces promotes rapidly reversible redox phase changes at room temperature as confirmed by calorimetry, X-ray diffraction, and titration for manganese average oxidation state. Water adsorption microcalorimetry (in situ) at room temperature measured the strongly exothermic integral enthalpy of water adsorption (-103.5 kJ/mol) and monitored the energetics of the redox phase transformation. Hydration-driven redox transformation of anhydrous nanophase Mn(III) 2O3, (high surface enthalpy of anhydrous surfaces 1.77 ± 0.10 J/m2) to Mn(II,III)3O4 (lower surface enthalpy 0.96 ± 0.08 J/m2) occurred during the first few doses of water vapor. Surface reduction of nanoparticle bixbyite (Mn 2O3) to hausmannite (Mn3O4) occurs under conditions where no such reactions are seen or expected on grounds of bulk thermodynamics in coarse-grained materials.
Layered structure manganese oxides contain alkali or alkaline earth cations and water, are generally fine-grained, and have considerable thermodynamic stability. The surface enthalpies (SE) of layered and tunnel structure complex manganese oxides are significantly lower than those of the binary manganese oxide phases. The SE for hydrous surfaces and overall manganese average oxidation state (AOS) (value in parentheses) are: cryptomelane 0.77 ± 0.10 J/m 2 (3.78), sodium birnessite 0.69 ± 0.13 J/m2 (3.56), potassium birnessite 0.55 ± 0.11 J/m2 (3.52), and calcium birnessite 0.41 ± 0.11 J/m2 (3.50). Surface enthalpies of hydrous surfaces of the calcium manganese oxide nanosheets are: δCa 0.39MnO2.3nH2O 0.75 ± 0.10 J/m2 (3.89) and δCa0.43MnO2.3nH2O 0.57 ± 0.12 J/m2 (3.68). The surface enthalpy of the complex manganese oxides appears to decrease with decreasing manganese average oxidation state, that is, with greater mixed valence manganese (Mn 3+/4+). Low surface energy suggests loose binding of H2O on the internal and external surfaces and may be critical to catalysis in both natural and technological settings.
Feng, Xueyan. "Nano-Scaled Frank-Kasper Supramolecular Lattice and Related Phase Transitions in Precisely Defined Giant Molecules Constructed by Functionalized Nanoparticles". University of Akron / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=akron1499356841029693.
Texto completoMakepeace, Andrew W. "Modeling the Behavior of Gold Nanoparticles and Semiconductor Nanowires for Utilization in Nanodevice Applications". Miami University / OhioLINK, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=miami1377015184.
Texto completoRoark, Brandon Kyle. "Nucleic Acid-Driven Quantum Dot-Based Lattice Formations for Biomedical Applications". Thesis, The University of North Carolina at Charlotte, 2017. http://pqdtopen.proquest.com/#viewpdf?dispub=10619578.
Texto completoWe present a versatile biosensing strategy that uses nucleic acids programmed to undergo an isothermal toehold mediated strand displacement in the presence of analyte. This rearrangement results in a double biotinylated duplex formation that induces the rapid aggregation of streptavidin decorated quantum dots (QDs). As biosensor reporters, QDs are advantageous to organic fluorophores and fluorescent proteins due to their enhanced spectral and fluorescence properties. Moreover, the nanoscale regime aids in an enhanced surface area that increase the number of binding of macromolecules, thus making cross-linking possible. The biosensing transduction response, in the current approach, is dictated by the analysis of the natural single particle phenomenon known as fluorescence intermittency, or blinking is the stochastic switching of fluorescence intensity ON (bright) and OFF (dark) states observed in single QD or other fluorophores. In contrast to binary blinking that is typical for single QDs, aggregated QDs exhibit quasi-continuous emission. This change is used as an output for the novel biosensing techniques developed by us. Analysis of blinking traces that can be measured by laser scanning confocal microscopy revealed improved detection of analytes in the picomolar ranges. Additionally, this unique biosensing approach does not require the analyte to cause any fluorescence intensity or color changes. Lastly, this biosensing method can be coupled with therapeutics, such as RNA interference inducers, that can be conditionally released and thus used as a theranostic probes.
Barton, Peter G. "Fabrication of Conductive Nanostructures by Femtosecond Laser Induced Reduction of Silver Ions". Thesis, Purdue University, 2017. http://pqdtopen.proquest.com/#viewpdf?dispub=10287501.
Texto completoNanofabrication through multiphoton absorption has generated considerable interest because of its unique ability to generate 2D and 3D structures in a single laser-direct-write step as well as its ability to generate feature sizes well below the diffraction limited laser spot size. The majority of multiphoton fabrication has been used to create 3D structures of photopolymers which have applications in a wide variety of fields, but require additional post-processing steps to fabricate conductive structures. It has been shown that metal ions can also undergo multiphoton absorption, which reduces the metal ions to stable atoms/nanoparticles which are formed at the laser focal point. When the focus is located at the substrate surface, the reduced metal is deposited on the surface, which allows arbitrary 2D patterning as well as building up 3D structures from this first layer. Samples containing the metal ions can be prepared either in a liquid solution, or in a polymer film. The polymer film approach has the benefit of added support for the 3D metallic structures; however it is difficult to remove the polymer after fabrication to leave a free standing metallic structure. With the ion solution method, free standing metallic structures can be fabricated but need to be able to withstand surface tension forces when the remaining unexposed solution is washed away.
So far, silver nanowires with resistivity on the order of bulk silver have been fabricated, as well as a few small 3D structures. This research focuses on the surfactant assisted multiphoton reduction of silver ions in a liquid solution. The experimental setup consists of a Coherent Micra 10 Ultrafast laser with 30fs pulse length, 80MHz repetition rate, and a wavelength centered at 800nm. This beam is focused into the sample using a 100x objective with a N.A. of 1.49. Silver structures such as nanowires and grid patterns have been produced with minimum linewidth of 180nm. Silver nanowires with resistivity down to 6x bulk silver have been fabricated. Three-dimensional structures have also been fabricated with up to a 10µm height at a thickness of 500nm. This method can fabricate structures with the possible applications in plasmonic metamaterials, photonic crystals, MEMS/NEMS and micro/nanocircuitry.
Rolsma, Caleb. "Study of the Mechanism of Irreversible Adsorption of Single-Walled Carbon Nanotubes to Sephacryl Hydrogel". Thesis, University of Colorado at Colorado Springs, 2017. http://pqdtopen.proquest.com/#viewpdf?dispub=10636224.
Texto completoAs a class of carbon-based nanomaterials, single-walled carbon nanotubes (SWNT) have many structural variations, called chiralities, each with different properties. Many potential applications of SWNT require the properties of a single chirality, but current synthesis methods can only produce single chiralities at prohibitive costs, or mixtures of chiralities at more affordable prices. Post-synthesis chirality separations provide a solution to this problem, and hydrogel separations are one such method.
Despite much work in this field, the underlying interactions between SWNT and hydrogel are not fully understood. During separation, large quantities of SWNT are irretrievably lost due to irreversible adsorption to the hydrogel, posing a major problem to separation efficiency, while also offering an interesting scientific problem concerning the interaction of SWNT with hydrogels and surfactants.
This thesis explores the problem of irreversible adsorption, offering an explanation for the process from a mechanistic viewpoint, opening new ways for improvement in separation. In brief, this work concludes adsorption follows three pathways, two of which lead to irreversible adsorption, both mediated by the presence of surfactants and limited by characteristics of the hydrogel surface. These findings stand to increase the general understanding of hydrogel SWNT separations, leading to improvements in separation, and bringing the research field closer to the many potential applications of single-chirality SWNT.
Heafey, Eve. "Applications of spectroscopy to the creation and study of nanostructures". Thesis, University of Ottawa (Canada), 2009. http://hdl.handle.net/10393/28476.
Texto completoCleroux, Carolyne. "Biodegradable nanoparticles for sustained occular drug delivery". Thesis, University of Ottawa (Canada), 2010. http://hdl.handle.net/10393/28485.
Texto completoHensen, Tucker Joseph. "Development of a Novel Additive Manufacturing Method| Process Generation and Evaluation of 3D Printed Parts Made with Alumina Nanopowder". Thesis, Colorado State University, 2018. http://pqdtopen.proquest.com/#viewpdf?dispub=10640617.
Texto completoDirect coagulation printing (DCP) is a new approach to extrusion-based additive manufacturing, developed during this thesis project using alumina nanopowder. The fabrication of complex ceramic parts, sintered to full density, was achieved and the details of this invention are described. With the use of additive manufacturing, complex features can be generated that are either very difficult or unattainable by conventional subtractive manufacturing methods. Three unique approaches were taken to create a slurry suitable for extrusion 3D-printing. Each represented a different method of suspending alumina nanopowder in a liquid; a bio-polymer gel based on chitosan, a synthetic polymer binder using poly-vinyl acetate (PVA), and electrostatic stabilization with the dispersant tri-ammonium citrate (TAC). It was found that TAC created a slurry with viscosity and coagulation rate that were tuneable through pH adjustment with nitric acid. This approach led to the most promising printing and sintering results, and is the basis of DCP. Taguchi and fractional factorial design of experiments models were used to optimize mixing of the alumina slurry, rheological properties, print quality, and sinterability. DCP was characterized by measuring the mechanical properties and physical characteristics of printed parts. Features as small as ~450 ?m in width were produced, in parts with overhangs and enclosed volumes, in both linear and radial geometries. After sintering, these parts exhibited little to no porosity, with flexural modulus and hardness comparing favorably with conventionally manufactured alumina parts. A remarkable aspect of DCP is that it is a completely binderless process, requiring no binder removal step. In addition, DCP can employ nanopowders, allowing for enhanced mechanical properties as observed in nano-grained materials. Perhaps most importantly, any material that acquires a surface charge when in aqueous media has the potential to be used in DCP, making it a method of additive manufacturing using many metals and ceramics other than alumina.
Bhattacharya, Indrasen. "Nanophotonic Devices Based on Indium Phosphide Nanopillars Grown Directly on Silicon". Thesis, University of California, Berkeley, 2018. http://pqdtopen.proquest.com/#viewpdf?dispub=10685771.
Texto completoIII-V optoelectronic device integration in a CMOS post-process compatible manner is important for the intimate integration of silicon-based electronic and photonic integrated circuits. The low temperature, self-catalyzed growth of high crystalline quality Wurtzite-phase InP nanopillars directly on silicon presents a viable approach to integrate high performance nano-optoelectronic devices.
For the optical transmitter side of the photonic link, InGaAs quantum wells have been grown in a core-shell manner within InP nanopillars. Position-controlled growth with varying pitch is used to systematically control emission wavelength across the same growth substrate. These nanopillars have been fabricated into electrically-injected quantum well in nanopillar LEDs operating within the silicon transparent 1400–1550 nm spectral window and efficiently emitting micro-watts of power. A high quality factor (Q ~ 1000) undercut cavity quantum well nanolaser is demonstrated, operating in the silicon-transparent wavelength range up to room temperature under optical excitation.
We also demonstrate an InP nanopillar phototransistor as a sensitive, low-capacitance photoreceiver for the energy-efficient operation of a complete optical link. Efficient absorption in a compact single nanopillar InP photo-BJT leads to a simultaneously high responsivity of 9.5 A/W and high 3dB-bandwidth of 7 GHz.
For photovoltaic energy harvesting, a sparsely packed InP nanopillar array can absorb ~90% of the incident light because of the large absorption cross section of these near-wavelength nanopillars. Experimental data based on wavelength and angle resolved integrating sphere measurements will be presented to discuss the nearly omnidirectional absorption properties of these nanopillar arrays.
Phillips, Rachel Huxford. "Nanoscale coordination polymers for anticancer drug delivery". Thesis, The University of North Carolina at Chapel Hill, 2013. http://pqdtopen.proquest.com/#viewpdf?dispub=3562787.
Texto completoThis dissertation reports the synthesis and characterization of nanoscale coordination polymers (NCPs) for anticancer drug delivery. Nanoparticles have been explored in order to address the limitations of small molecule chemotherapeutics. NCPs have been investigated as drug delivery vehicles as they can exhibit the same beneficial properties as the bulk metal-organic frameworks as well as interesting characteristics that are unique to nanomaterials.
Gd-MTX (MTX = methotrexate) NCPs with a MTX loading of 71.6 wt% were synthesized and stabilized by encapsulation within a lipid bilayer containing anisamide (AA), a small molecule that targets sigma receptors which are overexpressed in many cancer tissues. Functionalization with AA allows for targeted delivery and controlled release to cancer cells, as shown by enhanced efficacy against leukemia cells. The NCPs were doped with Ru(bpy)32+ (bpy = 2,2'-bipyridine), and this formulation was utilized as an optical imaging agent by confocal microscopy.
NCPs containing the chemotherapeutic pemetrexed (PMX) were synthesized using different binding metals. Zr-based materials could not be stabilized by encapsulation with a lipid bilayer, and Gd-based materials showed that PMX had degraded during synthesis. However, Hf-based NCPs containing 19.7 wt% PMX were stabilized by a lipid coating and showed in vitro efficacy against non-small cell lung cancer (NSCLC) cell lines. Enhanced efficacy was observed for formulations containing AA.
Additionally, NCP formulations containing the cisplatin prodrug disuccinatocisplatin were prepared; one of these formulations could be stabilized by encapsulation within a lipid layer. Coating with a lipid layer doped with AA rendered this formulation an active targeting agent. The resulting formulation proved more potent than free cisplatin in NSCLC cell lines. Improved NCP uptake was demonstrated by confocal microscopy and competitive binding assays.
Finally, a Pt(IV) oxaliplatin prodrug was synthesized and incorporated in different NCPs using various binding metals. A moderate drug loading of 44.9 wt% was determined for Zr-based NCPs. This drug loading, along with a diameter less than 200 nm, make these particles promising candidates for further stabilization via lipid encapsulation.
Davenport, Matthew W. "Synthetic Nanopores| Biological Analogues and Nanofluidic Devices". Thesis, University of California, Irvine, 2013. http://pqdtopen.proquest.com/#viewpdf?dispub=3565849.
Texto completoNanoscopic pores in biological systems – cells, for example – are responsible for regulating the transport of ionic and molecular species between physiologically distinct compartments maintained by thin plasma membranes. These biological pores are proteinaceous structures: long, contorted chains of chemical building blocks called amino acids. Protein pores have evolved to span a staggering range of shapes, sizes and chemical properties, each crucial to a pore's unique functionality.
Protein pores have extremely well-defined jobs. For instance, pores called ion channels only transport ions. Within this family, there are pores designated to selectively transport specific ions, such as sodium channels for sodium, chloride channels for chloride and so on. Further subdivisions exist within each type of ion channel, resulting in a pantheon of specialized proteins pores.
Specificity and selectivity are bestowed upon a pore through its unique incorporation and arrangement of its amino acids, which in turn have their own unique chemical and physical properties. With hundreds of task-specific pores, deciphering the precise relationship between form and function in these protein channels is a critical, but daunting task. In this thesis, we examine an alternative for probing the fundamental mechanisms responsible for transport on the nanoscale.
Solid-state membranes offer well-defined structural surrogates to directly address the science underlying pore functionality. Numerous protein pores rely on electronic interactions, size exclusion principles and hydrophobic effects to fulfill their duties, regardless of their amino acid sequence. Substituting an engineered and well-characterized pore, we strive to achieve and, thus, understand the hallmarks of biological pore function: analyte recognition and selective transport.
While we restrict our study to only two readily available membrane materials – one a polymer and the other a ceramic – nanofabrication techniques give us access to a virtually limitless combination of pore shapes and sizes. Exploiting this, we investigate the role of pore geometry in mediating the electrostatic and steric interactions responsible for transport on the nanoscale. Through targeted chemical modifications of our homogenous pores, we easily tailor their surface properties to investigate the role of hydrophobic effects in confined environments. Unbound by the physiological limitations of protein structures (such as sensitivity to electrolyte composition and fragility to external forces), our report concludes with the fusion of fabrication and modification considerations to design robust components for nanofluidic circuitry and nanoscopic biosensors.
Gleason, Russell. "Nanosphere lithography applied to magnetic thin films". Thesis, California State University, Long Beach, 2013. http://pqdtopen.proquest.com/#viewpdf?dispub=1524199.
Texto completoMagnetic nanostructures have widespread applications in many areas of physics and engineering, and nanosphere lithography has recently emerged as promising tool for the fabrication of such nanostructures. The goal of this research is to explore the magnetic properties of a thin film of ferromagnetic material deposited onto a hexagonally close-packed monolayer array of polystyrene nanospheres, and how they differ from the magnetic properties of a typical flat thin film. The first portion of this research focuses on determining the optimum conditions for depositing a monolayer of nanospheres onto chemically pretreated silicon substrates (via drop-coating) and the subsequent characterization of the deposited nanosphere layer with scanning electron microscopy. Single layers of permalloy (Ni80Fe20) are then deposited on top of the nanosphere array via DC magnetron sputtering, resulting in a thin film array of magnetic nanocaps. The coercivities of the thin films are measured using a home-built magneto-optical Kerr effect (MOKE) system in longitudinal arrangement. MOKE measurements show that for a single layer of permalloy (Py), the coercivity of a thin film deposited onto an array of nanospheres increases compared to that of a flat thin film. In addition, the coercivity increases as the nanosphere size decreases for the same deposited layer. It is postulated that magnetic exchange decoupling between neighboring nanocaps suppresses the propagation of magnetic domain walls, and this pinning of the domain walls is thought to be the primary source of the increase in coercivity.
Lounis, Sebastien Dahmane. "The influence of dopant distribution on the optoelectronic properties of tin-doped indium oxide nanocrystals and nanocrystal films". Thesis, University of California, Berkeley, 2015. http://pqdtopen.proquest.com/#viewpdf?dispub=3686398.
Texto completoColloidally prepared nanocrystals of transparent conducting oxide (TCO) semiconductors have emerged in the past decade as an exciting new class of plasmonic materials. In recent years, there has been tremendous progress in developing synthetic methods for the growth of these nanocrystals, basic characterization of their properties, and their successful integration into optoelectronic and electrochemical devices. However, many fundamental questions remain about the physics of localized surface plasmon resonance (LSPR) in these materials, and how their optoelectronic properties derive from their underlying structural properties. In particular, the influence of the concentration and distribution of dopant ions and compensating defects on the optoelectronic properties of TCO nanocrystals has seen little investigation.
Indium tin oxide (ITO) is the most widely studied and commercially deployed TCO. Herein we investigate the role of the distribution of tin dopants on the optoelectronic properties of colloidally prepared ITO nanocrystals. Owing to a high free electron density, ITO nanocrystals display strong LSPR absorption in the near infrared. Depending on the particular organic ligands used, they are soluble in various solvents and can readily be integrated into densely packed nanocrystal films with high conductivities. Using a combination of spectroscopic techniques, modeling and simulation of the optical properties of the nanocrystals using the Drude model, and transport measurements, it is demonstrated herein that the radial distribution of tin dopants has a strong effect on the optoelectronic properties of ITO nanocrystals.
ITO nanocrystals were synthesized in both surface-segregated and uniformly distributed dopant profiles. Temperature dependent measurements of optical absorbance were first combined with Drude modeling to extract the internal electrical properties of the ITO nanocrystals, demonstrating that they are well-behaved degenerately doped semiconductors displaying finite conductivity at low temperature and room temperature conductivity reduced by one order of magnitude from that of high-quality thin film ITO.
Synchrotron based x-ray photoelectron spectroscopy (XPS) was then employed to perform detailed depth profiling of the elemental composition of ITO nanocrystals, confirming the degree of dopant surface-segregation. Based on free carrier concentrations extracted from Drude fitting of LSPR absorbance, an inverse correlation was found between surface segregation of tin and overall dopant activation. Furthermore, radial distribution of dopants was found to significantly affect the lineshape and quality factor of the LSPR absorbance. ITO nanocrystals with highly surface segregated dopants displayed symmetric LSPRs with high quality factors, while uniformly doped ITO nanocrystals displayed asymmetric LSPRs with reduced quality factors. These effects are attributed to damping of the plasmon by Coulombic scattering off ionized dopant impurities.
Finally, the distribution of dopants is also found to influence the conductivity of ITO nanocrystal films. Films made from nanocrystals with a high degree of surface segregation demonstrated one order of magnitude higher conductivity than those based on uniformly doped crystals. However, no evidence was found for differences in the surface electronic structure from one type of crystal to the other based on XPS and the exact mechanism for this difference is still not understood.
Several future studies to further illuminate the influence of dopant distribution on ITO nanocrystals are suggested. Using synchrotron radiation, detailed photoelectron spectroscopy on clean ITO nanocrystal surfaces, single-nanoparticle optical measurements, and hard x-ray structural studies will all be instructive in elucidating the interaction between oscillating free electrons and defect scattering centers when a plasmon is excited. In addition, measurements of temperature and surface treatment-dependent conductivity with carefully controlled atmosphere and surface chemistry will be needed in order to better understand the transport properties of ITO nanocrystal films. Each of these studies will enable better fundamental knowledge of the plasmonic properties of nanostructures and improve the development of nanocrystal based plasmonic devices.
Suri, Baladitya. "Transmon qubits coupled to superconducting lumped element resonators". Thesis, University of Maryland, College Park, 2015. http://pqdtopen.proquest.com/#viewpdf?dispub=3711371.
Texto completoI discuss the design, fabrication and measurement at millikelvin-temperatures of Al/AlOx/Al Josephson junction-based transmon qubits coupled to superconducting thin-film lumped element microwave resonators made of aluminum on sapphire. The resonators had a center frequency of around 6GHz, and a total quality factor ranging from 15,000 to 70,000 for the various devices. The area of the transmon junctions was about 150 nm × 150 nm and with Josephson energy EJ such that 10GHz ≤ EJ ≤ 30 GHz. The charging energy of the transmons arising mostly from the large interdigital shunt capacitance, was Ec/h ≈ 300MHz.
I present microwave spectroscopy of the devices in the strongly dispersive regime of circuit quantum electrodynamics. In this limit the ac Stark shift due to a single photon in the resonator is greater than the linewidth of the qubit transition. When the resonator is driven coherently using a coupler tone, the transmon spectrum reveals individual "photon number'' peaks, each corresponding to a single additional photon in the resonator. Using a weighted average of the peak heights in the qubit spectrum, I calculated the average number of photons n¯ in the resonator. I also observed a nonlinear variation of n¯ with the applied power of the coupler tone Prf. I studied this nonlinearity using numerical simulations and found good qualitative agreement with data.
In the absence of a coherent drive on the resonator, a thermal population of 5.474 GHz photons in the resonator, at an effective temperature of 120 mK resulted in a weak n = 1 thermal photon peak in the qubit spectrum. In the presence of independent coupler and probe tones, the n = 1 thermal photon peak revealed an Autler-Townes splitting. The observed effect was explained accurately using the four lowest levels of the dispersively dressed Jaynes-Cummings transmon-resonator system, and numerical simulations of the steady-state master equation for the coupled system.
I also present time-domain measurements on transmons coupled to lumped-element resonators. From T1 and Rabi oscillation measurements, I found that my early transmon devices (called design LEv5) had lifetimes (T1 ∼ 1 μs) limited by strong coupling to the 50 Ω transmission line. This coupling was characterized by the the rate of change of the Rabi oscillation frequency with the change in the drive voltage (dfRabi /dV) – also termed the Rabi coupling to the drive. I studied the design of the transmon-resonator system using circuit analysis and microwave simulations with the aim being to reduce the Rabi coupling to the drive. By increasing the resonance frequency of the resonator ωr/2π from 5.4 GHz to 7.2 GHz, lowering the coupling of the resonator to the transmission line and thereby increasing the external quality factor Qe from 20,000 to 70,000, and reducing the transmon-resonator coupling g/2π from 70 MHz to 40 MHz, I reduced the Rabi coupling to the drive by an order of magnitude (∼ factor of 20). The T 1 ∼ 4 μs of devices in the new design (LEv6) was longer than that of the early devices, but still much shorter than the lifetimes predicted from Rabi coupling, suggesting the presence of alternative sources of noise causing qubit relaxation. Microwave simulations and circuit analysis in the presence of a dielectric loss tangent tan δ ≃ 5 × 10 -6 agree reasonably well with the measured T 1 values, suggesting that surface dielectric loss may be causing relaxation of transmons in the new designs.
Kats, Mikhail A. "Optics at interfaces: ultra-thin color coatings, perfect absorbers, and metasurfaces". Thesis, Harvard University, 2013. http://dissertations.umi.com/gsas.harvard:11275.
Texto completoEngineering and Applied Sciences
Pan, Hanqing. "Heat-induced reshaping and coarsening of metal nanoparticle-graphene oxide hybrids". Thesis, California State University, Long Beach, 2014. http://pqdtopen.proquest.com/#viewpdf?dispub=1526943.
Texto completoGlutathione-capped gold nanoparticles of size 1, 3, and 10 nm, CTAB-stabilized gold nanorods, as well as ro-carboxylate-functionalized palladium nanoparticles were synthesized and self-assembled onto graphene oxide to study their coarsening or reshaping behaviors upon heating at different temperatures ranging from 50 °C to 300 °C. These engineered nanoparticle- or nanorod-graphene oxide hybrid materials were studied by transmission electron microscopy (TEM), thermogravimetric analysis (TGA), Fourier-transform infrared (FTIR) spectroscopy, and UV-Vis spectroscopy.
The spherical nanoparticles would undergo coalescence to become larger particles and the nanorods would undergo reshaping to spherical particles. UV-Vis results show that the plasmonic band of gold nanoparticles at 520 nm would shift to higher wavelength indicating the coarsening into larger particles upon heating. Transmission electron microscopy results were generally in good agreements with the UV-Vis results and would be used as a direct tool to observe the structural changes of gold nanoparticles upon heat treatments.
Without the presence of graphene oxide, the nanoparticle coalescence began at the temperature between 150 and 200 °C for all three nanoparticles with different core sizes. But with the presence of graphene oxide, nanoparticles start to coalesce at the temperature below 150 °C. The gold nanorods have two plasmonic bands at ∼780 and ∼520 nm. The bands at ∼780 nm for gold nanorods would disappear when the gold nanorods-graphene oxide is heated at 50 °C indicating the complete reshaping of nanorods even at such a low temperature. Gold nanorods themselves are more stable and do not undergo the reshaping completely until the sample is heated above 150 °C. Since graphene oxide is an excellent thermal conductor, we propose that graphene oxide could transfer heat to the nanoparticles and nanorods efficiently, disrupt the interaction of stabilizing ligands, and make them to either coalesce or undergo reshaping at a lower temperature.
Nanoparticle- and nanorod-graphene oxide hybrid materials were also used to study the effect of covalent and non-covalent interactions between gold nanoparticles or nanorods and graphene oxide during coarsening or reshaping, respectively. Non-covalent interactions were studied by directly adding graphene oxide to aqueous solutions containing water-soluble metal nanoparticles or nanorods, and covalent interactions were achieved by the self-assembly of the same nanoparticles onto thiolated graphene oxide that was prepared by coupling L-cystine using 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide (EDC) and N-hydroxysuccinimide (NHS). When nanoparticles and nanorods are attached to graphene oxide through additional -covalent bonds, they are more strongly immobilized and therefore would undergo less coalescence and slower reshaping upon heating.
Sharma, Sumeet. "All Plasmonic Noble Metal Modulator". Thesis, California State University, Long Beach, 2019. http://pqdtopen.proquest.com/#viewpdf?dispub=10978327.
Texto completoAt present modulators in communications industry utilize non-linear materials like indium tin oxide (ITO) and DLD-164 as a dielectric, which makes the fabrication process cumbersome and expensive. This thesis discusses the possibility of using only gold and air as conductor and dielectric to characterize a signal modulating device. Both electro-absorption modulation (EAM) and phase change driven modulation is possible with the design. For the change in phase a length of 2.992 µm for the modulating arm of a Mach-Zehnder modulator (MZM) was achieved for operation at 525 nm. High absorptions of electromagnetic (EM) waves was seen at the 480 nm mark allowing a length of just 4.95 µm for EAM. The results suggest that an all plasmonic noble metal modulator utilizing air as a dielectric is possible for operation in the visible 400 nm to 700 nm range. The concept is supported by proof-of-principle based simulations.
This thesis proposes a novel idea of an all plasmonic modulator driven by changes in free carrier concentration in gold and surface plasmon polariton (SPP) excitations under an applied potential. The prototype model is simulated using a commercial finite difference time domain solver. The simulation enviro nment allows Maxwell’s equations to be solved in the time domain to investigate light propagation and absorption characteristics under an externally applied electric potential. The free carrier concentration dependent permittivity of gold is exploited to investigate possible applications in nano-photonics and optical communications.
Walker, Janelle. "An analysis of plasticity in the rat respiratory system following cervical spinal cord injury and the application of nanotechnology to induce or enhance recovery of diaphragm function". Thesis, Wayne State University, 2016. http://pqdtopen.proquest.com/#viewpdf?dispub=10153445.
Texto completoSecond cervical segment spinal cord hemisection (C2Hx) results in ipsilateral hemidiaphragm paralysis. However, the intact latent crossed phrenic pathway can restore function spontaneously over time or immediately following drug administration.
WGA bound fluorochromes were administered to identify nuclei associated with diaphragm function in both the acute and chronic C2Hx models. WGA is unique in that it undergoes receptor mediated endocytosis and is transsynaptically transported across select physiologically active synapses. Comparison of labeling in the acutely injured to the chronically injured rat provided an anatomical map of spinal and supraspinal injury induced synaptic plasticity. The plasticity occurs over time in the chronic C2Hx model in an effort to adapt to the loss of hemidiaphragm function.
Utilizing the selectivity of WGA, a nanoconjugate was developed to target drug delivery to nuclei involved in diaphragm function post C2Hx in an effort to restore lost function. Theophylline was selected due to its established history as a respiratory stimulant. Theophylline was attached to gold nanoparticles by a transient bond designed to degrade intracellularly. The gold nanoparticles were then permanently attached to WGA-HRP. Following intradiaphragmatic injection, the WGA portion was identified in the ipsilateral phrenic nuclei and bilaterally in the rVRGs. The location of WGA should reflect the location of the AuNP since the peptide bond between them is permanent.
The effectiveness of the nanoconjugate was verified with EMG analysis of the diaphragm and recordings from the phrenic nerves. All doses administered in the acute C2Hx model resulted in resorted hemidiaphragm and phrenic nerve activity. A dose of 0.14mg/kg had a significantly higher percent recovery on day 3, whereas 0.03mg/kg was significantly higher on day 14. The change in most effective dose over time is likely due to the availability or concentration of the drug and location of drug release. Administration of the nanoconjugate was also characterized in the chronically C2Hx model. The dose 0.06mg/kg resulted in significant recovery when injected 12 weeks post-C2Hx. This data suggests that WGA bound nanoconjugates are able to undergo endocytosis. In addition, the theophylline bound nanoconjugate is capable of restoring hemidiaphragm and phrenic nerve activity.
Akinlalu, Ademola V. "Structural analysis and characterization of synthesized ordered mesoporous silicate (MCM-41) using small angle X-rays scattering and complementary techniques". Thesis, Rensselaer Polytechnic Institute, 2016. http://pqdtopen.proquest.com/#viewpdf?dispub=10158526.
Texto completoMesoporous silicate have widespread potential applications, such as drug delivery, supports for catalysis, selective adsorption and host to guest molecules. Most important in the area of scientific research and industrial applications is their demand due to its extremely high surface areas (> 800m 2g−1) and larger pores with well defined structures.
Mesoporous silicate (MCM-41) samples were prepared by hydrothermal method under various chemo-physical conditions and various experimental methods such as small angle X-rays scattering (SAXS), Nitrogen adsorption-desorption analysis at 77 K, Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM) were employed to investigate the changes in the structural morphology and subtle lattice parameter changes. With regards to the subtle changes in the structural characteristics of the synthesized mesoporous silicate, we seek to understand the electron density function changes as the synthesis parameter are varied from low molar concentration of ATAB/Si to higher concentration, the system becoming more acidity due to increase in the hydrolysis time of pH regulator as a result of increased production of ethanol and acetic acid and the changes due to extended reaction time.
This Ph.D. research tries to understand the influence of various parameters like surfactant-Si molar ratio, reaction time, and the hydrolysis of the pH regulator on the orderliness/disorderliness of the lattice order, lattice spacing and electron density function. The stages during synthesis are carefully selected to better understand where the greater influence on the overall structural morphology exist so as to be able to ne tune this parameter for any desired specification and application.
The SAXS measurement were conducted on a HECUS S3-Micro X-ray system at Rensselaer Polytechnic Institute, Troy, NY. while the data evaluation and visualization were carried in 3DView 4.2 and EasySWAXS software. The electron density functions were generated with a proprietary software called edens.
In this dissertation, the following observations have been revealed resulting from SAXS measurement.
1. As one increases the hydrolysis duration of ethyl acetate, a gradual collapse of the lattice spacing of the mesoporous silcate MCM-41 is observed. We found from SAXS that there is a slight right shift of the spectra toward the higher q-values indicating that we are gradually losing orderliness in the lattice spacing and hexagonal structure of the mesoporous silica. Also, the intensity of the peak of second and third peaks are diminutive when compared to sample with shorter hydrolysis time.
2. A comparison of the SAXS spectra for the different molar concentration sample reveals that the 0:5M samples shows a deteriorating structural characteristics as compared to the 0:25 and 0:75M samples respectively and a clear decrease in the (100) reflection planes. Also noticed is the slight rightward shift in the overall spectrum prole. This observation suggest that further analysis is needed so as to better understand the result.
3. We establish that during MCM-41 synthesis, longer reaction time is needed to produce quality sample with well defined structurally characteristic for its intended application because according to spectrum for the sample with a longer reaction time (aging), a shift towards the lower q-values indicates that a sample with a larger lattice parameter and wall thickness but the intensities of its peak are diminishing when compared to the other of relatively shorter reaction time.
Other complementary techniques were used to corroborated the result obtained from SAXS. Nitrogen adsorption-desorption analysis at 77K was used to generate the isotherms while B.E.T method was used in conjunction with the isotherms to obtained the very important surface area information. SEM provide a visual structural morphology of the samples and FTIR gave the fingerprint detail of the bonds and vibration types between particle present.
Glover, Christopher Cash. "Investigation of a Contact Resonance Atomic Force Microscopy Scan Speed Phenomenon". Thesis, University of Nevada, Reno, 2018. http://pqdtopen.proquest.com/#viewpdf?dispub=10813816.
Texto completoThere are many unexplained phenomena that have been observed via atomic force microscopy (AFM) experiments. Understanding the cause of these phenomena is important to perform more accurate quantitative imaging using contact-resonance AFM and other contact-mode AFM techniques at higher scan speeds. This thesis presents evidence to confirm the existence of a scan speed dependent contact-mode AFM phenomenon and applies a squeeze film hydrodynamic lubrication model to explain it. Contact-resonance spectroscopy is used to investigate the phenomenon in which, above a critical scan speed, there is a monotonic decrease in the measured contact-resonance frequency with increasing scan speed. The observed phenomenon was replicated on a mica sample in a randomized set of AFM experiments performed at the National Institute for Standards and Technology (NIST). A literature review revealed that there is a thin water film that exists on mica under certain relative humidity (RH) conditions that has dynamic properties. The squeeze film hydrodynamic lubrication model predicts the general trend observed in the experimental data. However, there exists a higher order model that can be used to investigate the scan speed phenomenon more completely.
Wu, Zhi. "Design, Fabrication, and Characterization of Subwavelength Metallic Structures". University of Dayton / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=dayton1312179645.
Texto completoJoshi, Bhuwan. "DESIGN AND STUDY OF PLASMONIC NANOSTRUCTURES FOR APPLICATIONS IN BIOLOGICAL DETECTION AND PHOTONICS". Kent State University / OhioLINK, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=kent1324762602.
Texto completoAbenojar, Eric Chua. "Investigation of Structural Effects on the AC Magnetic Properties of Iron Oxide Nanoparticles". Case Western Reserve University School of Graduate Studies / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=case1516187103909374.
Texto completoYang, Xiaozhou. "Exploring Nanomechanical Properties of Natural Melanosomes via Atomic Force Microscopy". University of Akron / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=akron1523215102019988.
Texto completoShang, Zhihao. "Water Collection from Air by Electrospinning Hygroscopic Nanofibers". University of Akron / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=akron1549363835073664.
Texto completoJi, Zhouxiang. "Nano-channel of Viral DNA Packaging Motor as Single Pore to Differentiate Peptides". The Ohio State University, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=osu1555016293008571.
Texto completoShadpour, Sasan. "HIERARCHICAL SELF-ASSEMBLY IN B4 PHASE MORPHOLOGIES CONTROLLED BY STRATEGICALLY PLACING CHIRAL CENTERS". Kent State University / OhioLINK, 2021. http://rave.ohiolink.edu/etdc/view?acc_num=kent1626269500504995.
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