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Articles 1 - 19 of 19
Full-Text Articles in Physical Sciences and Mathematics
Comparative Study Of Field Enhancement Between Isolated And Coupled Metal Nanoparticles: An Analytical Approach, Greg Sun, Jacob B. Khurgin
Comparative Study Of Field Enhancement Between Isolated And Coupled Metal Nanoparticles: An Analytical Approach, Greg Sun, Jacob B. Khurgin
Physics Faculty Publications
We present an analytical model that takes into account the coupling between the surface plasmon modes in complex metal nanostructures. We apply this model to evaluate the field enhancement in the gap of two coupled Au metal spheres embedded in GaN dielectric and compare the result with that obtained by the single sphere. The results show additional improvement can be obtained in the gap depending on the width of the gap. This approach offers a clear physical insight for the enhancement and a straightforward method for optimization.
Systematic Approach To Electrostatically Induced 2d Crystallization Of Nanoparticles At Liquid Interfaces, Sumit Kewalramani, Suntao Wang, Yuan Lin, Huong Giang Nguyen, Qian Wang, Masafumi Fukuto, Lin Yang
Systematic Approach To Electrostatically Induced 2d Crystallization Of Nanoparticles At Liquid Interfaces, Sumit Kewalramani, Suntao Wang, Yuan Lin, Huong Giang Nguyen, Qian Wang, Masafumi Fukuto, Lin Yang
Faculty Publications
We report an experimental demonstration of a strategy for inducing two-dimensional (2D)crystallization of charged nanoparticles on oppositely charged fluid interfaces. This strategy aims to maximize the interfacial adsorption of nanoparticles, and hence their lateral packing density, by utilizing a combination of weakly charged particles and a high surface charge density on the planar interface. In order to test this approach, we investigated the assembly of cowpea mosaic virus (CPMV) on positively charged lipid monolayers at the aqueous solution surface, by means of in situX-ray scattering measurements at the liquid–vapor interface. Theassembly was studied as a function of the solution …
Enhanced Electrochemistry Of Nanoparticle-Embedded Polyelectrolyte Films: Interfacial Electronic Coupling And Distance Dependence, Callie E. Dowdy, Michael C. Leopold
Enhanced Electrochemistry Of Nanoparticle-Embedded Polyelectrolyte Films: Interfacial Electronic Coupling And Distance Dependence, Callie E. Dowdy, Michael C. Leopold
Chemistry Faculty Publications
Factors affecting the electronic communication believed to be responsible for the enhanced solution electrochemistry observed at electrodes modified with hybrid polyelectrolyte–nanoparticle (PE–NP) film assemblies were systematically investigated. Specifically, the faradaic current and voltammetric peak splitting recorded for cyclic voltammetry of ferricyanide redox species (Fe(CN)63−/4−) at films constructed with various architectures of citrate-stabilized gold NPs embedded in polyelectrolyte films composed of poly-l-lysine and poly-S-styrene were used to establish the relative importance of both distance and electronic coupling. Layer-by-layer construction of PE–NP films allowed for the position and density of NPs to be varied within the film to assess electronic coupling between …
Synthesis And Characterization Of An Europium-Porphyrin Complex, Alejandro Blinder
Synthesis And Characterization Of An Europium-Porphyrin Complex, Alejandro Blinder
All Capstone Projects
Photodynamic therapy (PDT) is a promising treatment that has continued to improve over the past thirty years when the first commercially approved photosensitizer (PS) was introduced. Although PDT has many successful applications, the terrifying number of new cancer cases reported each year makes scientists focus their efforts towards the development of new efficient PS for PDT. The biggest obstacle that prohibits PDT from becoming a more widely used therapy is the ineffective photosensitizers (PS) that are available on the market today. The purpose of this study was to evaluate the synthesized metal-porphyrin complex as a possible candidate as a PS. …
Self-Assembly Of Nanoparticles At Liquid-Liquid Interfaces, Kan Du
Self-Assembly Of Nanoparticles At Liquid-Liquid Interfaces, Kan Du
Open Access Dissertations
In this thesis, we studied the self-assembly of nanoparticles at liquid metal-water interfaces and oil-water interfaces. We demonstrated a simple approach to form nanostructured electronic devices by self-assembly of nanoparticles at liquid metal surfaces. In this approach, two liquid-metal droplets, which were coated with a monolayer of ligand-stabilized nanoparticles, were brought into contact. They did not coalesce but instead remained separated by the nanoparticles assembled at the interface. Devices formed by this method showed electron transport between droplets that was characteristic of the Coulomb blockade, where current was suppressed below a tunable threshold voltage because of the energy of charging …
Phenomena Characterization Of Energy Materials By X-Ray Absorption Spectroscopy, Ming-Yao Cheng, Chun-Jen Pan, Ju-Hsiang Cheng, Bing-Joe Hwang
Phenomena Characterization Of Energy Materials By X-Ray Absorption Spectroscopy, Ming-Yao Cheng, Chun-Jen Pan, Ju-Hsiang Cheng, Bing-Joe Hwang
Journal of Electrochemistry
The aim of this review is to introduce the characterization of energy materials by X-ray absorption spectroscopy (XAS) . This technique allows us to probe changes in the valance state and the local environment of the targeted element in the active material; thereby,leading to a better understanding of its electrochemical behavior,and hopefully showing the way to improved performance. Here,electrocatalysts for fuel cells and active electrode materials for Li-ion batteries are taken as the examples that illustrate the capability of XAS and allow observation and theory to be correlated with electrochemical phenomena.
Mechanistic Studies Of In Vitro Cytotoxicity Of Poly(Amidoamine) Dendrimers In Mammalian Cells, Sourav Prasanna Mukherjee, Fiona Lyng, Amaya Garcia, Maria Davoren, Hugh Byrne
Mechanistic Studies Of In Vitro Cytotoxicity Of Poly(Amidoamine) Dendrimers In Mammalian Cells, Sourav Prasanna Mukherjee, Fiona Lyng, Amaya Garcia, Maria Davoren, Hugh Byrne
Articles
Poly(amidoamine) (PAMAM) dendrimer nanoparticles have been demonstrated to elicit a well defined cytotoxicological response from mammalian cell lines, the response increasing systematically with dendrimer generation and number of surface amino groups. In this work, using generation G4, G5, and G6 dendrimers, this systematic response is furthermore demonstrated for the generation of reactive oxygen species, lysosomal activity, and the onset of apoptosis and levels of DNA damage. The results are consistent with a pathway of localisation of PAMAM dendrimers in the mitochondria leading to ROS production causing oxidative stress, apoptosis and DNA damage. ROS production is co-located in the mitochondria, and …
Effect Of Particle Properties And Light Polarization On The Plasmonic Resonances In Metallic Nanoparticles, U. Guler, R. Turan
Effect Of Particle Properties And Light Polarization On The Plasmonic Resonances In Metallic Nanoparticles, U. Guler, R. Turan
U. Guler
The resonance behavior of localized surface plasmons in silver and gold nanoparticles was studied in the visible and near-infrared regions of the electromagnetic spectrum. Arrays of nano-sized gold (Au) and silver (Ag) particles with different properties were produced with electron-beam lithography technique over glass substrates. The effect of the particle size, shape variations, period, thickness, metal type, substrate type and sulfidation were studied via transmission and reflectance measurements. The results are compared with the theoretical calculations based on the DDA simulations performed by software developed in this study. We propose a new intensity modulation technique based on localized surface plasmons …
Core-Shell Nanoparticles: Synthesis, Design, And Characterization, Kyler Carroll
Core-Shell Nanoparticles: Synthesis, Design, And Characterization, Kyler Carroll
Theses and Dissertations
The design of core/shell nanoparticles is of great interest for a wide range of applications. The primary focus of this dissertation is on the design and optimization of two synthetic routes. The first one is an aqueous reduction method using sodium borohydride and sodium citrate. This method was extended to design two types of core/shell nanoparticles, both of which have many applications in bio-sensing, magnetic resonance imaging, and magnetically guided SERS for the identification of environmental threats. The first, Fe/Ag core/shell nanoparticles were designed using a novel one-pot method by varying the AgNO3 addition time in the system. For …
Enhanced Oxygen Activation Over Supported Bimetallic Au-Ni Catalysts, Bert D. Chandler, Cormac G. Long, John D. Gilbertson, Christopher J. Pursell, G. Vijayaraghavan, K. J. Stevenson
Enhanced Oxygen Activation Over Supported Bimetallic Au-Ni Catalysts, Bert D. Chandler, Cormac G. Long, John D. Gilbertson, Christopher J. Pursell, G. Vijayaraghavan, K. J. Stevenson
Chemistry Faculty Research
New bimetallic Ni-Au supported nanoparticle catalysts were prepared by using dendrimer templated nanoparticles. Amine-terminated generation 5 polyamidoamine (PAMAM) dendrimers were anchored to a commercial silica with a siloxane linked anhydride. The dendrimer was then alkylated and used to template Ni-Au nanoparticles, which were subsequently extracted into organic solution as thiol monolayer protected clusters (MPCs). Transmission electron microscopy (TEM) and energy dispersive spectroscopy (EDS) indicated bimetallic nanoparticles of about 2 nm in size. Nanoparticles were deposited onto P-25 TiO2, and the capping thiol ligands were removed under flowing H2. DRIFTS infrared spectra of adsorbed CO showed only Au on the catalyst …
Theoretical Investigation Of The Structures And Stability Of Gas Phase Neutral And Cationic Tixoy Clusters., Baljeet Kaur
Theoretical Investigation Of The Structures And Stability Of Gas Phase Neutral And Cationic Tixoy Clusters., Baljeet Kaur
Theses and Dissertations
Theoretical investigation of the structure and stability of neutral and cationic TixOy cluster series (where y =2x-1, 2x, 2x+1) have been performed. The lowest lying structures for the neutral clusters are usually found in the singlet state. Generally, in bulk and in the case of the neutral TixOy clusters, the 2x cluster series is relatively more abundant than the 2x-1 and the 2x+1 cluster series. But in the case of cationic TixOy clusters, the 2x-1 series is more abundant. To understand the origin of the stability of the TixO2x-1+ clusters, we use density functional theory within the NRLMOL set of …
Chemically Directed Immobilization Of Nanoparticles Onto Gold Substrates For Orthogonal Assembly Using Dithiocarbamate Bond Formation, Mh Park, Xx Duan, Y Ofir, B Creran, D Patra, Xy Ling, J Huskens, Vm Rotello
Chemically Directed Immobilization Of Nanoparticles Onto Gold Substrates For Orthogonal Assembly Using Dithiocarbamate Bond Formation, Mh Park, Xx Duan, Y Ofir, B Creran, D Patra, Xy Ling, J Huskens, Vm Rotello
Vincent Rotello
Dithiocarbamate-mediated bond formation combined with soft lithography was used for the selective immobilization of amine-functionalized silica nanoparticles on gold substrates. The available amine groups on the upper surface of the immobilized silica nanoparticles were further utilized for postdeposition of additional materials including particles, dyes, and biomolecules. The robustness of dithiocarbamate-mediated immobilization enables orthogonal assembly on surfaces via selective removal of the masking thiol ligands using iodine vapor etching followed by further functionalization.
Sorption Of Bovine Serum Albumin On Nano And Bulk Oxide Particles, Lei Song
Sorption Of Bovine Serum Albumin On Nano And Bulk Oxide Particles, Lei Song
Masters Theses 1911 - February 2014
Manufactured oxide nanoparticles (NPs) have large production and widespread applications, which will inevitably enter the environment. NPs can interact with proteins in living beings due to the fact that NPs can transport into blood or across cell membranes into cells. Conformational change of protein molecules after sorption on oxide NPs has been reported. Therefore, it is important to understand the adsorption mechanism of protein onto oxide NPs surfaces. Although few works have reported protein adsorption behaviors, a general systematic comparison of the effects of particle size and surface groups on protein adsorption by widely studied NPs still needs to be …
Plasmon Enhanced Near-Field Interactions In Surface Coupled Nanoparticle Arrays For Integrated Nanophotonic Devices, Amitabh Ghoshal
Plasmon Enhanced Near-Field Interactions In Surface Coupled Nanoparticle Arrays For Integrated Nanophotonic Devices, Amitabh Ghoshal
Electronic Theses and Dissertations
The current thrust towards developing silicon compatible integrated nanophotonic devices is driven by need to overcome critical challenges in electronic circuit technology related to information bandwidth and thermal management. Surface plasmon nanophotonics represents a hybrid technology at the interface of optics and electronics that could address several of the existing challenges. Surface plasmons are electronic charge density waves that can occur at a metal-dielectric interface at optical and infrared frequencies. Numerous plasmon based integrated optical devices such as waveguides, splitters, resonators and multimode interference devices have been developed, however no standard integrated device for coupling light into nanoscale optical circuits …
Optical Properties Of Photopolymer Layers Doped With Aluminophosphate Nanocrystals, Elsa Leite, Tzvetanka Babeva, E Ng, Vincent Toal, Svetlana Mintova, Izabela Naydenova
Optical Properties Of Photopolymer Layers Doped With Aluminophosphate Nanocrystals, Elsa Leite, Tzvetanka Babeva, E Ng, Vincent Toal, Svetlana Mintova, Izabela Naydenova
Articles
The optical properties of photopolymer layers consisting of an acrylamide–based matrix and microporous aluminophosphate nanocrystals of AEI- type are investigated. The compatibility of the photopolymer doped with the nanoparticles is studied. The surface and volume properties of the layers with different levels of doping with microporous nanocrystals are characterized. The effective refractive indices and absorption coefficients of the doped photopolymer layers are determined and used to calculate the refractive index and porosity of pure AEI nanoparticles used as dopants. Volume transmission gratings were recorded in the doped photopolymer layers at different spatial frequencies. By spatial monitoring of the characteristic Raman …
Corrosion Protection Of Aa 2024-T3 Aluminium Alloys Using 3, 4-Diaminobenzoic Acid Chelated Zirconium-Silane Hybrid Sol-Gels, P.C. Rajath Varma, John Colreavy, John Cassidy, Mohamed Oubaha, Colette Mcdonagh, Brendan Duffy
Corrosion Protection Of Aa 2024-T3 Aluminium Alloys Using 3, 4-Diaminobenzoic Acid Chelated Zirconium-Silane Hybrid Sol-Gels, P.C. Rajath Varma, John Colreavy, John Cassidy, Mohamed Oubaha, Colette Mcdonagh, Brendan Duffy
Articles
Organic-inorganic polymers formed by hydrolysis/condensation reactions of alkoxide precursors, such as organically modified silanes (Ormosils) have found applications as electronic, optical and protective coatings. Such coatings possess important characteristics such as chemical stability, physical strength and scratch resistance. Further performance improvement is achieved through the incorporation of zirconium and titanium based nanoparticles, also formed through the sol-gel process. However due to the inherent difference in the reactivity of the precursors, the hydrolysis of each precursor must be carried out separately before being combined for final condensation. Zirconium precursors are commonly chelated using acetic acid or acetyl acetonate prior to hydrolysis, …
Supported Mono And Bimetallic Platinum And Iron Nanoparticles Electronic, Structural, Catalytic, And Vibrational Properties, Jason Robert Croy
Supported Mono And Bimetallic Platinum And Iron Nanoparticles Electronic, Structural, Catalytic, And Vibrational Properties, Jason Robert Croy
Electronic Theses and Dissertations
Catalysis technologies are among the most important in the modern world. They are instrumental in the realization of a variety of products and processes including chemicals, polymers, foods, pharmaceuticals, fuels, and fuel cells. As such, interest in the catalysts that drive these processes is ongoing, and basic research has led to significant advances in the field, including the production of more environmentally friendly catalysts that can be tuned at the molecular/atomic level. However, there are many factors which influence the performance of a catalyst and many unanswered questions still remain. The first part of this work is concerned with the …
Effects Of Silver Nanoparticles On Photochemical Processes Focusing On Luminol Chemiluminescence, Scott Milam
Effects Of Silver Nanoparticles On Photochemical Processes Focusing On Luminol Chemiluminescence, Scott Milam
Master's Theses and Doctoral Dissertations
Silver nanoparticles of varying sizes were synthesized. Their effects on enhancing or quenching the photochemical processes of tryptophan fluorescence, a ruthenium complex decay constant and chemiluminescence of luminol and ferricyanide, were studied. The tryptophan fluorescence was slightly enhanced by smaller nanoparticles and showed slight quenching in the presence of larger nanoparticles. The tris (2,2’-bipyridyl ruthenium (II) chloride) complex was excited using a 532 nm laser, and the decay constant was measured. Neither gold nor silver nanoparticles showed an impact on this process. The luminol chemiluminescence was studied with an emphasis on holding the concentration of nanoparticles, surface area, and silver …
Far-Field Optical Nanoscopy Based On Continuous Wave Laser Stimulated Emission Depletion, C. Kuang, Wei Zhao, Guiren Wang
Far-Field Optical Nanoscopy Based On Continuous Wave Laser Stimulated Emission Depletion, C. Kuang, Wei Zhao, Guiren Wang
Faculty Publications
Stimulated emission depletion (STED) microscopy is one of the breakthrough technologies that belong to far-field optical microscopy and can achieve nanoscale spatial resolution. We demonstrate a far-field optical nanoscopy based on continuous wave lasers with different wavelengths, i.e., violet and green lasers for excitation and STED, respectively. Fluorescent dyes Coumarin 102 and Atto 390 are used for validating the depletion efficiency. Fluorescent nanoparticles are selected for characterizing the spatial resolution of the STED system. Linear scanning of the laser beams of the STED system along one line of a microscope slide, which is coated with the nanoparticles, indicates that a …