Nanoscience and Nanotechnology Commons^™

Investigations Into Size And Surface Control Of Silicon Nanocrystals For Improved Optical Properties, James Donald Barnes

Dissertations and Theses

The discovery of visible photoluminescence (PL) from nanocrystalline porous silicon in 1990 led to extensive research into the mechanisms of the emergent properties, and optimization of these properties, for use in applications. The widespread use of silicon nanoparticles (Si NPs) in commercial applications is currently limited by three main factors: 1) poor radiative recombination efficiency of the interband transition, 2) instability of the interband photoluminescence, and 3) a lack of scalable methods for producing Si NPs that are both highly crystalline and size monodisperse.

To address these limitations, this dissertation correlates changes in the photoluminescence properties of hydrogen passivated silicon …

Quantum Transport Of The 2d Surface State In A Nonsymmorphic Semimetal, Xue Liu, Jin Hu, Jiang Wei, Chunlei Yue, Sergey V. Erohin, Yanglin Zhu, Abin Joshy, Jinyu Liu, Ana M. Sanchez, David Graf, Pavel B. Sorokin, Zinqiang Mao

Physics Faculty Publications and Presentations

In a topological semimetal with Dirac or Weyl points, the bulk-boundary correspondence principle predicts a gapless edge mode if the essential symmetry is still preserved at the surface. The detection of such topological surface state has been considered as the fingerprint prove for crystals with nontrivial topological bulk band. On the contrary, it has been proposed that even with symmetry broken at the surface, a new surface band can emerge in nonsymmorphic topological semimetals. The symmetry reduction at the surface lifts the bulk band degeneracies and produces an unusual “floating” surface band with trivial topology. Here, we first report quantum …

Maize Tassel Detection From Uav Imagery Using Deep Learning, Aziza Alzadjali, Mohammed H. Alali, Arun Narenthiran Weeranampalayam Sivakumar, Jitender S. Deogun, Stephen Scott, James C. Schnable, Yeyin Shi

Department of Mechanical and Materials Engineering: Faculty Publications

The timing of flowering plays a critical role in determining the productivity of agricultural crops. If the crops flower too early, the crop would mature before the end of the growing season, losing the opportunity to capture and use large amounts of light energy. If the crops flower too late, the crop may be killed by the change of seasons before it is ready to harvest. Maize flowering is one of the most important periods where even small amounts of stress can significantly alter yield. In this work, we developed and compared two methods for automatic tassel detection based on …

Optical Engineering Of Iii-Nitride Nanowire Light-Emitting Diodes And Applications, Ha Quoc Thang Bui

Dissertations

Applications of III-nitride nanowires are intensively explored in different emerging technologies including light-emitting diodes (LEDs), laser diodes, photodiodes, biosensors, and solar cells. The synthesis of the III-nitride nanowires by molecular beam epitaxy (MBE) is investigated with significant achievements. III-nitride nanowires can be grown on dissimilar substrates i.e., silicon with nearly dislocation free due to the effective strain relaxation. III-nitride nanowires, therefore, are perfectly suited for high performance light emitters for cost-effective fabrication of the advanced photonic-electronic integrated platforms. This dissertation addresses the design, fabrication, and characterization of III-nitride nanowire full-color micro-LED (µLED) on silicon substrates for µLED display technologies, high-efficient …

Controlled Reduction Of Graphene Oxide And Graphene Oxide-Carbon Nanotube Hybrids And Their Applications, Samar Azizighannad

Dissertations

Graphene and graphene derivatives are widely used in diverse research and industrial applications. Graphene production on a large scale is carried out by exfoliating graphite oxide and producing graphene oxide (GO), which comprises of graphene sheets with different oxygen-containing functional groups such as hydroxyl, carboxyl, and carbonyl. GO is reduced to reduced graphene oxide (rGO), which has properties that are closer to graphene. Properties of GO and rGO depend upon the oxygen content, and the effect of reducing oxygen content on the aqueous behavior of rGOs is not well understood.

In an effort to understand how properties of rGO change …

Uavs For Vegetation Monitoring: Overview And Recent Scientific Contributions, Ana I. De Castro, Yeyin Shi, Joe Mari Maja, Jose M. Pena

Department of Mechanical and Materials Engineering: Faculty Publications

This paper reviewed a set of twenty-one original and innovative papers included in a special issue on UAVs for vegetation monitoring, which proposed new methods and techniques applied to diverse agricultural and forestry scenarios. Three general categories were considered: (1) sensors and vegetation indices used, (2) technological goals pursued, and (3) agroforestry applications. Some investigations focused on issues related to UAV flight operations, spatial resolution requirements, and computation and data analytics, while others studied the ability of UAVs for characterizing relevant vegetation features (mainly canopy cover and crop height) or for detecting different plant/crop stressors, such as nutrient content/deficiencies, water …

Three-Dimensional Shape Analysis Of Peripapillary Retinal Pigment Epithelium-Basement Membrane Layer Based On Oct Radial Images, Junfei Tong, Pengfei Dong, Sachin Kedar, Deepta Ghate, Linxia Gu

Department of Mechanical and Materials Engineering: Faculty Publications

The peripapillary retinal pigment epithelium-basement membrane (ppRPE/BM) layer angle was recently proposed as a potential index for estimating intracranial pressure noninvasively. However, the ppRPE/BM layer angle, measured from the optical coherence tomography (OCT) scans, varied across the radial directions of the optic disc. This made the ppRPE/BM layer angle difficult to be utilized in its full potential. In this study, we developed a mathematical model to quantify the ppRPE/BM layer angles across radial scans in relation to the ppRPE/BM 3D morphology in terms of its 3D angle and scanning tilt angles. Results showed that the variations of the ppRPE/BM layer …

Chitosan/Gelatin/Silver Nanoparticles Composites Films For Biodegradable Food Packaging Applications., Sreelekha Ediyilyam, Bini George, Sarojini Sharath Shankar, Thomas Thuruthiyil Dennis, Stanisław Wacławek, Miroslav Černík, Vinod V T Padil

Department of Medicine Faculty Papers

The food packaging industry explores economically viable, environmentally benign, and non-toxic packaging materials. Biopolymers, including chitosan (CH) and gelatin (GE), are considered a leading replacement for plastic packaging materials, with preferred packaging functionality and biodegradability. CH, GE, and different proportions of silver nanoparticles (AgNPs) are used to prepare novel packaging materials using a simple solution casting method. The functional and morphological characterization of the prepared films was carried out by using Fourier transform infrared spectroscopy (FTIR), UV-Visible spectroscopy, and scanning electron microscopy (SEM). The mechanical strength, solubility, water vapor transmission rate, swelling behavior, moisture retention capability, and biodegradability of composite …

Experimental Investigation Of Surface Resistivity Of Yttrium Stabilized Zirconium As A Thin Film, Matthew J. Melfi

Seton Hall University Dissertations and Theses (ETDs)

Solid Oxide Fuel Cells are devices that use electrochemical reactions to convert chemical energy from fuel to electricity. In comparison with coal power plants, a Solid Oxide Fuel Cell, produces a higher electrical conversion efficiency. However, at higher temperatures (1000°C) it creates a lower ionic conductivity, which limit the Solid Oxide Fuel Cells. When lowering the temperature, the ohmic resistance increases. In our research, an Yttrium Stabilized Zirconium layer will be produced from a fine dimple grain structure allowing high flow of oxygen mobility. This mobility increases ionic conductivity and decrease ohmic loss. The goal of our research is first …

On The Comparison Of Flow Physics Between Minimal And Extended Flow Units In Turbulent Channels, Ethan A. Davis, Siamak Mirfendereski, Jae Sung Park

Department of Mechanical and Materials Engineering: Faculty Publications

Direct numerical simulations were performed to study the effects of the domain size of a minimal flow unit (MFU) and its inherent periodic boundary conditions on flow physics of a turbulent channel flow in a range of 200 ≤ Re_τ ≤ 1000. This was accomplished by comparing turbulent statistics with those computed in sub-domains (SD) of extended domain simulations. The dimensions of the MFU and SD were matched, and SD dynamics were set to minimize artificial periodicities. Streamwise and spanwise dimensions of healthy MFUs were found to increase linearly with Reynolds number. It was also found that both MFU …

Impact Of Angiogenic And Osteogenic Factors In The Presence Of Biodegradable Piezoelectric Films, Jayla Millender

Honors Scholar Theses

One of the most common causes of bone graft rejection is lack of a vascular network connecting the graft to the existing native tissue – allowing for nutrient flow. Under current grafting techniques, the existing blood vessel network in the patient slowly invades the implant in order to supply the injured site with its necessary nutrients. The purpose of this research is to determine if a synthetic bone graft with a stable microvascular network can be developed in vitro. I hypothesize that the use of indirect angiogenic factors such as sonic hedgehog homolog and hypoxia-inducible factor-1 in combination with the …

An Investigation Of Testing Parameters On The Frictional Properties Of Patterned Core-Shell Nanostructures, Colin Phelan

Graduate Theses and Dissertations

Friction tests are a beneficial means to analyze the tribological characteristics and advantages of materials and textured surfaces. However, the selected test parameters can significantly influence the results. This work explores the significance of the friction testing parameters on the frictional performances of core-shell nanostructure-textured surfaces (CSNTSs). Several applied normal loads (10 μN, 100 μN, and 500 μN) and diamond counterface indenter tip radii (1 μm, 5 μm, and 20 μm) were selected for the testing of Al/diamond-like-carbon (DLC) and Al/amorphous silicon (a-Si) CSNTSs. The measured friction values of the CSNTSs were then compared to a matching Al/DLC film and …

Designing Cryogenic Strain Device For 2d Materials, Jake Carter

Mechanical Engineering Undergraduate Honors Theses

The Churchill lab working within the Physics Department at the University of Arkansas is working to create important quantum states including weak topological insulators (TIs) through the use of symmetry engineering and topological electronic states in two-dimensional (2D) crystals of WHM materials. Experimental results of these topological states have been obstructed due to the difficulty to perform controlled in situ strain. This project strives to create a mount to utilize a piezoelectric nanopositioner within cryostats achieving an in situ strain that creates the quantum states the lab is looking to observe. This report also examines the necessary equations to determine …

Characterization Of Protein Aggregation Using A Solid-State Nanopore Device, Mitu Chandra Acharjee

Graduate Theses and Dissertations

Protein aggregation has been linked to many chronic and devastating neurodegenerative human diseases and is also strongly associated with aging. In the case of neurodegenerative diseases, α, β tubulins and tau proteins dissociate in a neuron cell and aggregate both intra and extra-cellularly. Tau and tubulin aggregations were found as one of the major causes of many neurodegenerative diseases, such as Parkinson’s, Picks, Alzheimer’s, Huntington, and Prion. Finding the state and mechanism of protein aggregation is significant. In this work, tau and tubulin aggregations were detected in ionic solutions using the solid-state nanopore technique. Besides tau and tubulin, aggregations of …

Mechanical Analysis Of A Heterogeneously Integrated Silicon Photonic Interposer, Erica Charlene Graham

Legacy Theses & Dissertations (2009 - 2024)

Overcoming the bandwidth bottleneck in conventional interconnects necessitates transitioning to alternative scaling paradigms. Silicon (Si) photonics is considered a disruptive technology, capable of meeting the growing demands for higher bandwidth, low latency, and power efficiency. By leveraging the intrinsic properties of optical signals and manufacturing compatibility of Si, the co-integration of Si photonics and complementary-metal-oxide-semiconductor (CMOS) circuitry leading to terabit data speeds for next generation data communication can be realized. Heterogeneously integrating Si photonic functionality with well-established CMOS technology in an Si photonic interposer architecture simultaneously provides independent optimization as well as close integration of both technologies in one platform. …

Statistical And Variational Modeling And Analysis Of Passive Integrated Photonic Devices, Norbert Dinyi Agbodo

Legacy Theses & Dissertations (2009 - 2024)

The success of Si as a platform for photonic devices and the associated availabilityof wafer-scale, ultra-high resolution lithography for Si CMOS has helped lead to the rapid advance of Si-based integrated photonics manufacturing over the past decade. This evolution is nearing the point of integration of Si-based photonics together with Si-CMOS for compact, high speed, high bandwidth, and cost-effective devices. However, due to the sensitive nature of passive and active photonic devices, variations inherent in wafer-based fabrication processes can lead to unacceptable levels of performance variation both within a give die and across a given wafer. Fully understanding the role …

Nanoscratch Study Of Diamond-Like Carbon Coatings With A Polydopamine + Sio2 Adhesive Underlayer, Anna Fisher

Mechanical Engineering Undergraduate Honors Theses

Diamond-like carbon (DLC) coatings have a wide array of desirable characteristics such as low friction, high hardness, and scratch resistance. Due to high residual stress and thermal mismatch, DLC films experience adhesion difficulties when bonded with metallic substrates, leading to cracking and delamination. In this study, the properties of a new coating with a polydopamine underlayer and silica nanoparticles bonded to a stainless-steel substrate (PDA+SiO2/DLC) were studied alongside three other samples, one with a polydopamine underlayer (PDA/DLC), one with a trimethylsilane (TMS) underlayer (TMS/DLC), and one with no underlayer (DLC only). Nanoscratch tests were performed with a 1 μm spheroconical …

Development Of A Laser-Assisted Chemical Vapor Deposition (Cvd) Technique To Grow Carbon-Based Materials, Abiodun Ademola Odusanya

Graduate Theses/Dissertations

Carbon-based materials (CBMs) including graphene, carbon nanotubes (CNT), highly ordered pyrolytic graphite (HOPG), and pyrolytic carbon (PyC) have gained so much attention in research in recent years because of their unique electronic, optical, thermal, and mechanical properties. CBMs are relatively very stable and have minimal environmental footprint. Various techniques such as mechanical exfoliation, pulsed laser deposition, and chemical vapor deposition (CVD) have been used to grow CBMs and among them thermal CVD is the most common. This study aims to explore ways of reducing the energy requirement to produce CBMs, and for that, a novel pulsed laser-assisted CVD technique had …

Exploration Of Antimicrobial And Cell Proliferation Properties Of Nanofibers Incorporating Nopal (O. Cochenillifera) Extract, Cristobal Rodriguez

Theses and Dissertations

This study focused on the fabrication of Forcespinning® nanofibers composed of Opuntia cochenillifera, ‘nopal’, mucilage (N) extract, chitosan (CH), and pullulan (PL) (N/CH/PL) were developed with an optimum fiber average diameter of 406±127 nm, and studied for their ability to sustain adhesion and proliferation of mouse embryonic fibroblast (NIH 3T3) cells. After a 6-day incubation period, N/CH/PL nanofibers displayed robust cell proliferation, while also exhibiting inhibitory properties through an N extract dip-coating process against gram-negative bacteria Escherichia coli in a 24 h bacterial growth study. A demonstration of integrated natural bioactive compounds with combined biodegradable polymers, provide an enhanced …

Peptoid-Functionalized Gold Nanoparticles For Zika Virus Envelope Protein Detection, Meagan Olsen

Chemical Engineering Undergraduate Honors Theses

Detection and identification of viral pathogens is essential in providing effective and rapid medical treatment. Well-established detection methods can be expensive, slow, and sometimes unable to provide the needed sensitivity and specificity. The Zika virus is one clinically relevant pathogen that cannot be easily identified due to cross-reactivity with other viruses from the same family. Electrochemical sensors enhanced with peptoid-functionalized gold nanoparticles (AuNPs) are an alternative to traditional techniques that offers rapid, accurate, label-free pathogen detection for point-of-care diagnostics. To this end, a peptoid capable of binding to the Zika virus envelope protein was developed and its binding affinity for …

Oxone® Mediated Tempo-Oxidized Cellulose Nanomaterials: Material Characterization, Ultrafiltration Membrane Separations, And Thin Film Composite Gas Transport Analysis, John Phillips Moore

Graduate Theses and Dissertations

Cellulose nanomaterials (CNMs) are derived from plant matter and are comprised of nanoscopic cellulose crystals and fibers. They have a diverse set of applications, from cosmetics to oil recovery. This study focuses on the properties of Oxone® mediated TEMPO-oxidized cellulose nanomaterials (OTO-CNMs) and their use in controlling the transport properties of polymeric substrates. Synthesis and characterization of cellulosic nanoparticles have resulted in the creation of OTO-CNMs with properties that increase hydrophilicity. With added hydrophilicity, OTO-CNMs possess lower fouling propensity, making them ideal membrane additive for transport limited separations such as hemodialysis.

To utilize the material and unique properties thereof, this …

Photothermal Response Induced By Nanocage-Coated Artificial Extracellular Matrix Promotes Neural Stem Cell Differentiation, Seunghyun Jung, Nathaniel Harris, Isabelle I. Niyonshuti, Samir V. Jenkins, Abdallah M. Hayar, Fumiya Watanabe, Azemat Jamshidi-Parsian, Jingyi Chen, Michael J. Borrelli, Robert J. Griffin

Mechanical Engineering Faculty Publications and Presentations

Strategies to increase the proportion of neural stem cells that differentiate into neurons are vital for therapy of neurodegenerative disorders. In vitro, the extracellular matrix composition and topography have been found to be important factors in stem cell differentiation. We have developed a novel artificial extracellular matrix (aECM) formed by attaching gold nanocages (AuNCs) to glass coverslips. After culturing rat neural stem cells (rNSCs) on these gold nanocage-coated surfaces (AuNC-aECMs), we observed that 44.6% of rNSCs differentiated into neurons compared to only 27.9% for cells grown on laminin-coated glass coverslips. We applied laser irradiation to the AuNC-aECMs to introduce precise …

Degradation Of Antibiotics In Aqueous Phase Using Pms Catalytic Decomposition With Zero-Valent Iron Nanoparticles Immobilized In Sba-15, Ahdee Bluma Zeidman

UNLV Theses, Dissertations, Professional Papers, and Capstones

Zero-valent iron nanoparticles (nZVI) have been studied as an option for soil remediation and water treatment for many years. The capability of nZVI to produce oxidation/reduction processes, depending on the reaction conditions, has attracted great interest with their major drawback being reactivity loss through agglomeration. The loss in nZVI surface area has been reported to be prevented through immobilization onto a porous media (e.g., SBA-15, MCM-41, or zeolites). In this work, a mesoporous silica structure (SBA-15) is used as an nZVI supporting material to enhance its reactivity and promote peroxymonosulfate (PMS) catalytic decomposition for the degradation of antibiotics in aqueous …

Tensile-Strained Germanium Quantum Dots Grown On Indium Aluminum Arsenide (111)A And (110) By Molecular Beam Epitaxy, Kathryn Eva Sautter

Boise State University Theses and Dissertations

Molecular beam epitaxy (MBE) enables the growth of semiconductor nanostructures known as tensile-strained quantum dots (TSQDs). The highly tunable nature of TSQD properties means that they are of interest for a wide variety of applications including for infrared (IR) lasers and light-emitting diodes (LEDs), improved tunnel junction efficiency in multijunction solar cell technology, quantum key encryption, and entangled photon emission. In this project, I focus on one of the most technologically important materials, germanium (Ge). Ge has a high gain coefficient, high electron mobility, and low band gap: all excellent properties for optoelectronic applications. Until recently, these technological advantages were …

Fabrication Of Forcespinning® Nanofibers Incorporating Nopal Extract, Cristobal Rodriguez, Victoria Padilla, Karen Lozano, J. Andrew Mcdonald, Luis Materon, Alejandra Chapa, Fariha Ahmad, Carlos Trevino De Leon, Robert Gilkerson

School of Integrative Biological & Chemical Sciences (Formerly Dept. of Biology)

In this study, nanofibers composed of Opuntia cochenillifera nopal mucilage (N) extract combined with chitosan (CH) and pullulan (PL) (N/CH/PL) were produced via Forcespinning®. The developed nonwoven composite membranes are comprised of long, continuous, and homogenous fibers with fiber average diameter varying between 251±77 nm and 406±127 nm depending on the concentration of N. After crosslinking, the developed membranes were highly stable in water. The water absorption capacity of the N/CH/PL composite nanofiber membranes was shown to be 65% higher when compared to the CH/PL nanofiber membranes. Nopal dipcoated membranes show inhibition of gram-negative Escherichia coli, indicating antibacterial properties. These …

Mixed Mode Crack Propagation In Iliac Bone, E. Baesu, Dm. Iliescu, Bv. Radoiu, S. Halichidis

Department of Mechanical and Materials Engineering: Faculty Publications

Bone is a complex material that can be regarded as an anisotropic elastic composite material. The problem of crack propagation in hu- man bone is analyzed by using a generalization of the maximum tensile stress criterion (MTS). The results concern the critical stress for crack propagation and the direction of the crack path in Iliac bone.

Special Issue “Cfd Modeling Of Complex Chemical Processes: Multiscale And Multiphysics Challenges”, Li Xi, De-Wei Yin, Jae Sung Park

Department of Mechanical and Materials Engineering: Faculty Publications

No abstract provided.

Application Of Atomically Precise Metal Nanoclusters In Electrocatalysis, Zhi-Hua Zhuang, Wei Chen

Journal of Electrochemistry

Metal nanoclusters (M NCs) consist of only several to a few hundred of metal atoms and possess core sizes less than 2 nm. Owing to the quantum size effect, the electronic states of M NCs evolve to discrete levels similar to the molecule energy gaps, other than a continuous density of states to produce plasmon characteristic of bulk metal nanoparticles (M NPs). In comparison with the conventional M NPs, M NCs exhibit dramatically unique electronic and optical properties, such as molecule-like energy gaps, strong photoluminescence and high catalytic properties, which make them promising for potential application in numerous fields, such …

Electrochemiluminescence Imaging Hydrogen Evolution Reaction On Single Platinum Nanoparticles Using A Bipolar Nanoelectrode Array, Xiang Qin, Zhong-Qiu Li, Jian-Bin Pan, Jian Li, Kang Wang, Xing-Hua Xia

Journal of Electrochemistry

A high-density (5.7 × 10⁸ cm^-2) nanoelectrode array with the electrode diameter of 200 nm and the interelectrode distance of 450 nm were fabricated. The nanoelectrode array consisted of gold nanowires embedded in a porous anodic aluminum oxide (AAO) matrix, having regular nanoelectrode distribution and highly uniform nanoelectrode size. The gold nanoelectrode array was used as a closed bipolar nanoelectrode array combined with electrochemiluminescence (ECL) method to map the electrocatalytic activity of platinum nanoparticles toward hydrogen evolution reaction (HER) by modifying the catalysts on single nanoelectrodes. Results show that HER on single bipolar nanoelectrodes could be imaged …

Electrochemical Gating Single-Molecule Circuits With Parallel Paths, Jun-Qing Su, Yi-Fan Zhou, Ling Tong, Ya-Hao Wang, Ju-Fang Zheng, Jing-Zhe Chen, Xiao-Shun Zhou

Journal of Electrochemistry

Electrochemical gating has emerged as a feasible and powerful method to tune single-molecule conductance. Herein, we demonstrate that the electron transport through single-molecule circuits with two benzene rings in parallel could be efficiently gated by electrochemistry. The molecular junctions with two parallel paths are fabricated with Au electrodes by STM break junction (STM-BJ) technique. Their conductance value exhibits a 2.82-fold enhancement by the constructive quantum interference compared to single-molecule junctions with single path for electron tunneling. Furthermore, the conductance of para-benzene based molecule could be electrochemically tuned with a modulation ratio of about 333%·V^-1. With the help of …