Nanoscience and Nanotechnology Commons^™

Bridging The Gap In Epsilon-Near-Zero Nonlinear Materials, Adam R. Ball

Theses and Dissertations

Studying how light and matter interact has been of interest to humans for thousands of years. From the invention of the first mirror, burning ants with a magnifying glass, to optical fiber communication, light has been central to mankind. Researchers have sought to take this to the extreme with nonlinear optics where intense laser light interacts with materials. The study of this thesis is to understand a new generation of materials that has come to light. Epsilon-near-zero (ENZ) materials have shown promise for ultrafast light manipulation in tandem with modern day CMOS compatible electronics. Here, I seek to bridge the …

Single-Atom Catalysts For Electrochemical Energy Conversion: Copper Single-Atom Catalyst For Oxygen Reduction Reaction And Quantification Of Site Density By Co Stripping Voltammetry, Dawatage Perera

Theses and Dissertations--Chemistry

Fuel cells are considered a promising technology for achieving cleaner and more sustainable energy production and utilization. However, one of the current major challenges is the economic viability associated with the extensive use of Pt group metal (PGM) catalysts, particularly on the cathode side. Therefore, non-PGM single-atom catalysts (SACs) have received considerable attention as alternatives for PGM catalysts in the oxygen reduction reaction (ORR), which occurs at the cathode of the fuel cell. Among various SAC structures, the non-PGM/nitrogen-doped carbon-based structure (M-N-C) stands out for its excellent ORR performance.

Chapter 2 illustrates the use of copper metal in place of …

Photoexcited Charge Carrier Dynamics And Electronic Properties Of Two-Dimensional Mxene, Nb2ctx, Andrew M. Fitzgerald, Emily Sutherland, Tarek A. Elmelegy, Mary Qin Hassig, Julia Martin, Erika Colin-Ulloa, Ken Ngo, Ronald L. Grimm, Joshua R. Uzarski, Michel W. Barsoum, N. Aaron Deskins, Lyubov V. Titova, Kateryna Kushnir Friedman

Mechanical Engineering

Two-dimensional, 2D, niobium carbide MXene, Nb2CTx, has attracted attention due to its extraordinarily high photothermal conversion efficiency that has applications ranging from medicine, for tumor ablation, to solar energy conversion. Here, we characterize its electronic properties and investigate the ultrafast dynamics of its photoexcitations with a goal of shedding light onto the origins of its unique properties. Through density functional theory, DFT, calculations, we find that Nb2CTx is metallic, with a small but finite density of states at the Fermi level for all experimentally relevant terminations of Nb2CTx that can be achieved using HF or molten salt etching of the …

Electrolyte/Electrode Interfacial Electrochemical Optimization Strategies For Durable Aqueous Zinc-Ion Batteries, Jingjing Niu

Chulalongkorn University Theses and Dissertations (Chula ETD)

Aqueous zinc ion batteries, as a type of secondary battery using inorganic aqueous solution as the electrolyte, are considered to be a strong contender in the field of future energy storage technologies due to their high theoretical electric capacity, high safety, low cost and environmental friendliness. However, aqueous zinc ion batteries also face some challenges. The first is the relatively low energy density, which requires further optimisation of electrode materials and battery structure. Secondly, the creation of zinc dendrites can reduce the cycling stability and safety of the battery. In addition, prolonging the cycle life is also a pressing issue. …

Development Of Janus Membrane From Electrospun Nanofiber For Membrane Distillation Processes, Michaela Olisha Lobregas

Chulalongkorn University Theses and Dissertations (Chula ETD)

The Janus membrane, characterized by surfaces with opposite wettability, represents an innovative design for membrane distillation (MD). This study introduces new methods for fabricating MD membranes with tailored surfaces to address fouling and wetting challenges in saline systems. A nanofibrous Janus membrane was developed, featuring an omniphobic substrate as the non-wetting layer and a hydrophilic top coating as the wetting layer. Using the dual-spinneret system for simultaneous electrospinning and electrospraying, a composite substrate membrane, comprising a loose network of PVDF nanofibers and PVDF-fluorinated TiO2 microclusters, was produced. This membrane exhibited high resistance to liquids, including water, glycerol, diiodomethane, and saline. …

Air Flow Behavior Assessment In Particulate Filtration Efficiency (Pfe) Tester Via Computational Fluid Dynamics (Cfd), Muhammad Amer

Chulalongkorn University Theses and Dissertations (Chula ETD)

Particulate Filtration Efficiency (PFE) assessment is critical for evaluating filter media. There are several PFE testing protocol depending on products and issuing countries, for example ASTM-F2299 standard for disposable medical masks, NIOSH-TEB-APR-STP-0059 for N and R series respirators, and ISO-29463 for HEPA filters. While the PFE testing principles of all standard are the same, their requirement, testing protocol and minute details are different. Air flow characteristic before and after filter media in testing chamber is very important to accuracy of PFE measurement, especially for ASTM F2299 standard. We have developed a custom PFE tester per ASTM F2299 using a simple …

Accelerating The Exploration Of High-Entropy Alloys: Synergistic Effects Of Integrating Computational Simulation And Experiments, Deyu Jiang, Yuhua Li, Liqiang Wang, Lai Chang Zhang

Research outputs 2022 to 2026

High-entropy alloys (HEAs) are novel materials composed of multiple elements with nearly equal concentrations and they exhibit exceptional properties such as high strength, ductility, thermal stability, and corrosion resistance. However, the intricate and diverse structures of HEAs pose significant challenges to understanding and predicting their behavior at different length scales. This review summarizes recent advances in computational simulations and experiments of structure-property relationships in HEAs at the nano/micro scales. Various methods such as first-principles calculations, molecular dynamics simulations, phase diagram calculations, and finite element simulations are discussed for revealing atomic/chemical and crystal structures, defect formation and migration, diffusion and phase …

Cellular Structure Mediated Dislocation Regulation In Additively Manufactured Refractory High Entropy Alloy, Changxi Liu, Lechun Xie, Lai-Chang Zhang, Liqiang Wang

Research outputs 2022 to 2026

A Ti1.5Nb1Ta0.5Zr1Mo0.5 (TNTZM) refractory high entropy alloy (HEA) with a cellular structure was successfully fabricated by laser powder bed fusion (L-PBF). Compression testing and cyclic deformation testing results revealed that, in the cellular structure, the cell walls could store dislocations. Furthermore, the local chemical order (LCO) plays a crucial role in controlling dislocations within the cell wall region. The LCO not only facilitates dislocation slip but also generates additional lattice distortion upon stress-induced LCO destruction to enable dislocation pinning. This work offers novel insights into the microstructure of additively manufactured refractory HEAs and uncovers a distinct dislocation regulation mechanism.

Tailored Micromagnet Sorting Gate For Simultaneous Multiple Cell Screening In Portable Magnetophoretic Cell-On-Chip Platforms, Jonghwan Yoon, Yumin Kang, Hyeonseol Kim, Abbas Ali, Keonmok Kim, Sri Ramulu Torati, Mi-Young Im, Changyeop Jeon, Byeonghwa Lim, Cheolgi Kim

Center for Bioelectronics Publications

Conventional magnetophoresis techniques for manipulating biocarriers and cells predominantly rely on large-scale electromagnetic systems, which is a major obstacle to the development of portable and miniaturized cell-on-chip platforms. Herein, a novel magnetic engineering approach by tailoring a nanoscale notch on a disk micromagnet using two-step optical and thermal lithography is developed. Versatile manipulations are demonstrated, such as separation and trapping, of carriers and cells by mediating changes in the magnetic domain structure and discontinuous movement of magnetic energy wells around the circumferential edge of the micromagnet caused by a locally fabricated nano-notch in a low magnetic field system. The motion …

Characterization And Measurement Limitations Using Non-Destructive Mueller Matrix Scatterometry (Mmse) And X-Ray Diffraction (Xxrd) Techniques For Gate All Around (Gaa) Transistor Test Structures: Limitations And Superlattice Effects In Advanced Si/Si(1-X)Ge(X) Superlattice Nanowire Test Structures And Measurability Of Simulated Horizontal Gaa Test Structures, Ezra Mel Beltran Pasikatan

Electronic Theses & Dissertations (2024 - present)

Advanced semiconductor devices are moving toward 3D geometries due to scaling demands and performance requirements. Nondestructive metrology necessary for process control of 3D structures must be advanced to facilitate their transition from technology development to high volume manufacturing. Thin film metrology using Mueller Matrix Spectroscopic Ellipsometry (MMSE) and X-ray Diffraction (XRD) film metrology, as well as patterned structure metrology using Optical Critical Dimension (OCD) and X-ray Fluorescence (XRF) techniques have proved capable of measuring the Si/ Si_(1-x)Ge_(x) superlattices and gate-all-around (GAA) transistor test structures. Because these techniques are indirect, their limitations associated with superlattice device structures need …

Electrodeposition Of Giant Magnetostrictive Transducers For A Fabricated Mixed Physics Signal Transmission Device, Mina Faltas

Nanoscience and Microsystems ETDs

Non-intrusive solutions for communication through a sealed metal vessel requires the use of piezoelectric transducers to transmit acoustic waves through the vessel wall. This approach suffers the disadvantage of compromised security because a potential eavesdropper could decipher the correlation between digital and electric signals of both sides of the system. One solution is a mixed physics system employing magnetostrictive transducers.

For a magnetostrictive transducer to work well in this application, it would have to have a high piezomagnetic constant. This is influenced by soft magnetism and saturation magnetostriction. Nickel-Iron-Cobalt alloys are modified to retain their soft magnetic properties while increasing …

Exploring Regular And Turbulent Flow States In Active Nematic Channel Flow Via Exact Coherent Structures And Their Invariant Manifolds, Caleb G. Wagner, Rumayel H. Pallock, Jae Sung Park, Michael M. Norton, Piyush Grover

Department of Mechanical and Materials Engineering: Faculty Publications

This work is a unified study of stable and unstable steady states of 2D active nematic channel flow using the framework of Exact Coherent Structures (ECSs). ECSs are stationary, periodic, quasiperiodic, or traveling wave solutions of the governing equations that, together with their invariant manifolds, organize the dynamics of nonlinear continuum systems. We extend our earlier work on ECSs in the preturbulent regime by performing a comprehensive study of stable and unstable ECSs for a wide range of activity values spanning the preturbulent and turbulent regimes. In the weakly turbulent regime, we compute more than 200 unstable ECSs that coexist …

Ionically Crosslinked Cellulose Nanocrystals By Metal Nitrates For The Preparation Of Stable Emulsions With Tunable Interface Properties, Joseph Batta-Mpouma, Gurshagan Kandhola, Jin-Woo Kim

Materials Science and Engineering Faculty Publications and Presentations

Biologically extracted cellulose nanocrystals (CNCs) are rod-like and amphiphilic materials with surface-exposed (hydrophilic sites) and hidden (hydrophobic sites) hydroxyl groups. These physicochemical characteristics make CNCs suitable for use as emulsifying agents to stabilize emulsions. Stable oil-in-water emulsions, using sulfated (i.e., – SO₃−) CNCs that were ionically crosslinked with alkaline-earth (i.e., Mg ²⁺) or transition-d-block (i.e., Zn ²⁺) metal cations, were developed without the use of any synthetic surfactants or prior functionalization of pure CNCs with hydrophobic molecules. Various emulsion surface properties such as interfacial tension, surface charge, surface chemistry, as well as rheology were characterized. Ionically …

Viability Of Magnetic Nanoparticles For Magnetic Hyperthermia Cancer Therapy, Marcos Adrian Garcia

Open Access Theses & Dissertations

Over the last few decades magnetic nanoparticles have gained an extraordinary amount of attention in the science community. Their versatile use in many different research areas such as medicine, engineering and technology and many other areas has made them a popular subject. In this thesis, the synthesis of different systems of magnetic nanoparticles will be explored along with the potential use of the MNP's as viable candidates for Magnetic Hyperthermia Cancer Therapy. With values of over 200 emu/g for Iron-Silver magnetic nanoparticles with particle sizes ranging from 30-70nm and their heating properties under an AC magnetic field. As well of …

Investigating Van Der Waals Josephson Junctions With 2h-Nbse2 And 1t’-Wte2, Kristine Lorraine Haley

UNLV Theses, Dissertations, Professional Papers, and Capstones

Josephson junctions have garnered significant attention due to their unique electronic properties and applications in quantum devices. In this thesis, we investigate the fabrication processes and characterization of two-dimensional (2D) Josephson junctions consisting of layered van der Waals materials: niobium diselenide (2H-NbSe₂) and few layered tungsten ditelluride (1T’-WTe₂). The reduction of dimensionality can bring forth unique characteristics in certain materials that are not seen in their bulk counterparts, making them prime candidates for physical exploration. 2H-NbSe₂ is an s-wave superconductor at temperatures near and below 7 K. 1T’-WTe₂ is a semimetal in bulk but …

The Shape Modulation Of Laser-Induced Nanowelded Microstructures Using Two Colors, Ariel Rogers, Isabelle Niyonshuti, Jun Ou, Diksha Shrestha, Deborah Okyere, Jingyi Chen, Yong Wang

Physics Faculty Publications and Presentations

The light-based nanowelding of metallic nanoparticles is of particular interest because it provides convenient and controlled means for the conversion of nanoparticles into microstructures and the fabrication of nanodevices. In this study, we investigated the wavelength dependence of laser-induced nanowelded shapes of silver nanoparticles (AgNPs). We observed that the nanowelded microstructures illuminated with only a 405 nm laser were more branched than those formed via illumination using both the 405 nm and 532 nm lasers. We quantified this observation by two compactness descriptors and examined the dependence of the power of the 532 nm laser. More importantly, to understand the …

Strategies For Optimizing Plasmonic Grating Couplers With A Topology-Based Inverse Design, Michael Efseaff, Mark C. Harrison

Engineering Faculty Articles and Research

Numerical simulations have become a cornerstone technology in the development of nanophotonic devices. Specifically, 3D finite-difference time domain (FDTD) simulations are widely used due to their flexibility and powerful design capabilities. More recently, FDTD simulations in conjunction with a design methodology called inverse design has become a popular way to optimize device topology, reducing a device’s footprint and increasing performance. We implement a commercial inverse design tool to generate complex grating couplers and explore a variety of grating coupler design methodologies. We compare the conventionally designed grating couplers to those generated by the inverse design tool. Finally, we discuss the …

Preparation And Lithium Storage Properties Of Carbon Confined Li3Vo4 Nano Materials, Jia-Qi Fan, Huan-Qiao Song, Jia-Ying An, Amantai A-Yi-Da-Na, Mo Chen

Journal of Electrochemistry

Li₃VO₄, as a promising anode material for lithium ion batteries, has been widely studied because of its low and safe voltage, and large capacity. However, its poor electronic conductivity impedes the practical application of Li₃VO₄ particularly at high rates. In this paper, carbon confined Li₃VO₄ nano materials (Li₃VO₄/C) were synthesized by hydrothermal and solid-phase method, and for comparison, the Li₃VO₄ (N) nano materials without carbon confinement and Li₃VO₄ (B) materials were also synthesized by pure solid-phase method. The composition, structure, …

Exploring The Interactions Of Copper High Aspect Ratio Structures (Cuhars), A Novel Metal-Organic Biohybrid Nanocomposite, With Chondrocytes, Tasneem Khasru

Master's Theses

Osteoarthritis (OA) is a prevalent degenerative joint disorder characterized by cartilage lesions and subchondral bone destruction (1). Addressing OA is challenging due to cartilage's avascular and aneural nature, unique cellular arrangement, and dense extracellular matrix (ECM). Current pharmacological treatments are mainly symptomatic and are unable to halt disease progression or reverse cartilage damage . Surgical interventions also come with complications. Tissue-engineered grafts using biomaterials and molecular manipulation have emerged as potential treatments for cartilage regeneration. Copper-containing scaffolds have shown promise in bone and cartilage regeneration. Nanotechnology offers new avenues, with nanoparticles and nanofibers being used in tissue engineering research. However, …

An Exploration Of Tissue Specific Impedance Using Microneedle Based Wearable Sensors, Kaitlyn J.H. Read

Nanoscience and Microsystems ETDs

Within this research, I have developed a microneedle-based wearable sensor for plants and fungi, to measure the electrical impedance of different tissues. Electrical impedance measures the physical properties of a material while allowing complex biological systems to be modeled onto a simplified electrical circuit. Microneedles allow for electrical impedance to measure specific tissues without the insulative properties of the cuticle and can be applied to delicate tissues. I have demonstrated the tissue specificity, novel attachment methods, as well as use on both plants and fungi. In chapter 1, I applied microneedle-based impedance to the leaf midrib of a sorghum and …

What Does It Mean To Be “Prepared For Work”? Perceptions Of New Engineers, Jessica R. Deters, Marie C. Paretti, Logan A. Perry, Robin Ott

Department of Mechanical and Materials Engineering: Faculty Publications

Background: Engineering education seeks to prepare students for engineering practice, but the concept of preparedness is often ill-defined. Moreover, findings from studies of different populations or in different contexts vary regarding how well new graduates are prepared. These variations, coupled with the lack of clarity, suggest the need to better understand what it means to be prepared for engineering work.

Purpose: This study contributes to research on workplace preparation by exploring how new graduates describe being prepared for engineering work.

Method: Applying secondary analysis to data from the multi-institution Capstone To Work (C2W) project, we used thematic …

Inverse Engineering Of Absorption And Scattering In Nanoparticles: A Machine Learning Approach, Alex Vallone, Nooshin M. Estakhri, Nasim Mohammadi Estrakhri

Engineering Faculty Articles and Research

We use a region-specified machine learning approach to inverse design highly absorptive multilayer plasmonic nanoparticles. We demonstrate the design of particles with a wide range of absorption to scattering ratios (i.e., cloaked absorbers and bright absorbers) and for different visible wavelengths.

Growth Of Germanium Thin Films On Sapphire Using Molecular Beam Epitaxy, Emmanuel Wangila, Peter Lytvyn, Hryhorii Stanchu, Calbi Gunder, Fernando Maia De Oliveira, Samir Saha, Subhashis Das, Niroshi Eldose, Chen Li, Mohammad Zamani-Alavijeh, Mourad Benamara, Yuriy I. Mazur, Shui-Qing Yu, Gregory J. Salamo

Electrical Engineering Faculty Publications and Presentations

Germanium films were grown on c-plane sapphire with a 10 nm AlAs buffer layer using molecular beam epitaxy. The effects of Ge film thickness on the surface morphology and crystal structure were investigated using ex situ characterization techniques. The nucleation of Ge proceeds by forming (111) oriented three-dimensional islands with two rotational twin domains about the growth axis. The boundaries between the twin grains are the origin of the 0.2% strain and tilt grains. The transition to a single-grain orientation reduces the strain and results in a better-quality Ge buffer. Understanding the role of thickness on material quality during the …

Impact Of Silicon Ion Irradiation On Aluminum Nitride-Transduced Microelectromechanical Resonators, David D. Lynes, Joshua Young, Eric Lang, Hengky Chandrahalim

Faculty Publications

Microelectromechanical systems (MEMS) resonators use is widespread, from electronic filters and oscillators to physical sensors such as accelerometers and gyroscopes. These devices' ubiquity, small size, and low power consumption make them ideal for use in systems such as CubeSats, micro aerial vehicles, autonomous underwater vehicles, and micro-robots operating in radiation environments. Radiation's interaction with materials manifests as atomic displacement and ionization, resulting in mechanical and electronic property changes, photocurrents, and charge buildup. This study examines silicon (Si) ion irradiation's interaction with piezoelectrically transduced MEMS resonators. Furthermore, the effect of adding a dielectric silicon oxide (SiO₂) thin film is …

Flexible And Sewable Electrode Based On Ni-Co@Pani-Salphen Composite-Coated On Textiles For Wearable Supercapacitor, Touba Rezaee Adriyani, Ali A. Ensafi, B. Rezaei

Chemistry & Biochemistry Faculty Publications and Presentations

Flexible electrodes with high deformability and energy density are critical for electronic textiles. The key factor for achieving high-performance supercapacitors with superior power and energy density is the evaluation of materials that exhibit exceptional capacitive performance. Herein, we have prepared Ni-Co nanoparticles at the surface of polyaniline-salphen (Ni-Co@PS). Then, followed by casting Ni-Co@PS on a conductive carbon cloth (CC) as a substrate through a facile in-situ polymerization strategy. The morphologies of Ni-Co@PS composite were characterized by different methods such as FE-SEM, XPS, XRD, BET, and electrochemical methods. This nanocomposite showed high tolerability and a large surface area with excellent behavior …

A Review On The Coalescence Of Confined Drops With A Focus On Scaling Laws For The Growth Of The Liquid Bridge, Sangjin Ryu, Haipeng Zhang, Udochukwu John Anuta

Department of Mechanical and Materials Engineering: Faculty Publications

The surface–tension-driven coalescence of drops has been extensively studied because of the omnipresence of the phenomenon and its significance in various natural and engineering systems. When two drops come into contact, a liquid bridge is formed between them and then grows in its lateral dimensions. As a result, the two drops merge to become a bigger drop. The growth dynamics of the bridge are governed by a balance between the driving force and the viscous and inertial resistances of involved liquids, and it is usually represented by power–law scaling relations on the temporal evolution of the bridge dimension. Such scaling …

Revealing Interface-Assisted Plastic Anisotropy Via In Situ Transmission Electron Microscopy Tension Of Lamellar Tial, Zhixiang Qi, Qi Zhu, Jian Wang, Yuede Cao, Fengrui Chen, Jiangwei Wang, Yang Chen, Gong Zheng, Guang Chen

Department of Mechanical and Materials Engineering: Faculty Publications

Assembling functional units into specific orientation organizations based on functional unit and organization (FUO) paradigm can maximize utilizing mechanical property anisotropy of lamellar-structured materials. However, the origin of their anisotropic deformation behaviors has not been clearly understood. Taking the fully lamellar γ-TiAl/ α₂-Ti₃Al dual-phase single crystal as an example, we decouple the interface functional units governed anisotropic plastic deformation through in situ transmission electron microscopy tensile testing and multiscale microstructural characterizations. The orientation organization-dependent slip continuity across the γ/α₂ interface and interface strength play a determinant role in plastic anisotropy beyond intrinsic dislocation activities within …

Top-Down Nanomanufacturing Of Anisotropic Two-Dimensional Metals, Md Rubayat-E Tanjil

USF Tampa Graduate Theses and Dissertations

Two-dimensional (2D) materials have introduced a transformative era in materials science with extensive research being performed to gain a fundamental understanding of their diverse properties and applications. Amongst the broader 2D material family, 2D metals or 2D metallic nanosheets (2DMNSs) typically denotes the nanometer-scale thin elemental metals, compound, or alloys, which shows superlative chemical and physical properties compared to bulk counterparts due to the reduced dimensionality. 2D materials’ widespread direct physical or chemical isolation techniques have been facilitated due to their intrinsic van der Waals layered morphology, whereas 3D close-packed bulk metals with isotropic bonding hinder their facile isolation in …

Charge-Dependence Of Dissolution/Deposition Energy Barrier On Cu(111) Electrode Surface By Multiscale Simulations, Hang Qiao, Yong Zhu, Sheng Sun, Tong-Yi Zhang

Journal of Electrochemistry

Behaviors of electrified interface under different applied potentials/charges play the central role in electroplating process and electrochemical corrosion. The mechanism, however, is unclear yet for a surface atom dissolving/depositing from/on an electrode surface under an applied potential. The energy barrier along the reaction path is the key variable. The present work conductes hybrid first-principle/hybrid calculations to study the direct and indirect dissolution/deposition of a Cu atom on perfect/stepped Cu(111) planar electrodes in an electrolyte under different excess charges. Energy profiles present a linear relationship between the energies of the initial/final state and the activation state of different reaction paths under …

Surface Modifications Of Lini0.96Co0.02Mn0.02O2 With Tungsten Oxide And Phosphotungstic Acid, Gang Zhao, Zheng-Liang Gong, Yi-Xiao Li, Yong Yang

Journal of Electrochemistry

With the rapid development of electric vehicles, enormous demands are made for higher energy density, better cycling performance and lower cost of lithium-ion batteries (LIBs). As an important high capacity cathode material for LIBs, the high nickel layered oxide material LiNi_0.8Co_0.1Mn_0.1O₂(NCM811) can reach an energy density of 760 Wh·kg^-1. The ultra-high nickel ternary positive electrode material (LiNi_1-x-yCo_xMn_yO₂, x ≥ 0.90) has a specific capacity of more than 210 mAh·g^-1, and can realize higher energy density. Besides, an ultra-high nickel material …